Dissertations / Theses: 'Cone beam computer tomography CBCT'

1

Zekry, Ahmed Khaled Ahmed Abdin. "Facial alveolar bone wall width: a cone beam computed tomography (CBCT) study in Asians." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48395663.

Full text

Abstract:

Background: The width of the facial alveolar bone wall is crucial for long term successful esthetic outcomes of implants immediately placed into extraction sockets. A threshold of 2 mm is recommended to minimize buccal vertical bone resorption. Aim: To assess the width of the facial alveolar bone wall using cone-beam computed tomography images (CBCT). Methods: Retrospective CBCT images were acquired from a representative sample of Asians using the i-CAT® classic system with a 0.4 mm voxel size. At random, 200 CBCT images were selected according to predefined criteria. The DICOM file was imported into the i-Cat Vision® software. In the panoramic screen, the middle of each tooth was selected and, in the sagittal window, the middle cross section was selected for performing the measurements using a computer. The vertical distance from the alveolar crest (BC) - CEJ was measured. The width of the facial alveolar bone wall was measured at three locations: 1, 3, and 5 mm apical to BC. Descriptive statistics, frequency analyses, and multi-level comparisons were performed. Results: The sample consisted of 74 males and 126 females (mean age of 37.2 years; range 17-82 years). A total of 3618 teeth were assessed. There was no significant difference between the values of right and left sides, or between genders. However, statistically significant differences were observed between age groups at all levels. The distance from CEJ-BC varied from 0.4 to 4mm, with an overall tendency to increase with age. The mean width of the facial alveolar bone wall at anterior teeth was 0.9 mm and increased towards posterior regions. Rarely, a width of 2 mm was yielded (0.6-1.8 % for anterior teeth, 0.7- 30.8 % for posterior teeth). At a 5mm distance from BC, minimal widths of facial alveolar bone were identified for the anterior teeth. The frequency of dehiscence ranged from 9.9- 51.6 % for anterior and 3.1- 53.6 % for posterior teeth, respectively. Conclusion and clinical implications: A thin facial alveolar bone wall was usually present in both jaws. Hence, for most patients, adjunctive bone augmentation may be needed when installing implants in areas of esthetic concern.
published_or_final_version
Dental Surgery
Master
Master of Dental Surgery

APA, Harvard, Vancouver, ISO, and other styles

2

Lalani, Sara. "Three-dimensional CBCT analysis of cranial base symmetry." Thesis, Boston University, 2015. https://hdl.handle.net/2144/37816.

Full text

Abstract:

Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2015 (Department of Orthodontics and Dentofacial Orthopedics).
Includes bibliographic references: leaves 37-42.
Background: Craniofacial skeletal asymmetry is a common finding in the general population that often goes undetected. Interest in this topic has led to many studies aimed at describing this type of asymmetry, its distribution and etioIogy. The cranial base, being cIosely related to the face and brain, is a key component in craniofacial growth and may also display varying amounts of asymmetry contributing to this anomaly. Though many studies have explored underlying skeletal asymmetry, most of them were limited by their two-dimensional method of investigation. With the advent of three-dimensional technology, more recent studies have had the advantage of studying the cranial base in its true anatomic form, resulting in greater accuracy of analysis. Despite access to this technoIogy, there is still a lack of literature regarding the cranial base in a normal population. Determining average skull base dimensions will provide a set of normative data that can be used as a reference for future studies. Material and Methods: Pre-treatment Cone Beam Computed Tomography (CBCT) films of 160 esthetic human subjects previously used by another investigator were screened for use in our current research. These DICOM files were imported into InVivoDental5.3 software (Anatomage[TM]; San Jose, Calif.) for screening and 70 CBCT scans were selected for analysis. All patients were classified as cervical vertebral stage 4 and above. The images were oriented in all three planes of space for uniformity and 14 bilateral anatomic landmarks were identified on each scan. A mid-sagittal reference plane was created using crista galli as the origin, and extending a perpendicular passing through the middle of the right and left clinoid points connected by a line, and through posterior points basion and opisthion. Each landmark was given an x-, y- and z- coordinate representing its three dimensional position and bilateral linear measurements to the reference plane were recorded using the software system. Statistical Analysis: InVivoDental5.3 software was used to calculate linear distances between each landmark and the mid-sagittal plane. This data was exported into Microsoft excel for analysis. Descriptive statistics of our sample and paired t-tests with a 5% significance level, or p value of 0.05, were performed. Results: The means of the right and left measurements of each bilateral landmark were calculated along with their standard deviations. A comparison between right and left means was accomplished with the use of paired t-tests. 12 1andmarks did not show a statistical difference in their locations on either side of the mid-sagittal plane. However, the means of 2 landmarks were found to be statistically significant. These were euryon (p = 0.01) and the jugular foramen (p = 0.00) Conclusion: The overall trend of our data indicated that the cranial base in a normal population, without craniofacial anomaly, displays symmetry, with the exception of the location of euryon and the jugular foramen. These findings are in accordance with those of similar three-dimensional studies. It is likely that the significant findings were due to tracing error, given the indiscrete location of euryon and the large, relatively asymmetric shape of the jugular foramen. However, if these structures are truly asymmetric, we can infer from our sample of symmetric patients, that there is no clinical relevance. Further studies with an increased sample size, additional landmarks or a more discrete sample can be performed to continue describing the skull base. The results of this study offer valuable reference data that can be used as a baseline for future studies.

APA, Harvard, Vancouver, ISO, and other styles

3

Giles, David. "Cone-beam computed tomography: imaging dose during CBCT scan acquisition and accuracy of CBCT based dose calculations." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95242.

Full text

Abstract:

Cone beam computed tomography (CBCT) is a recent development in radiotherapy for use in image guidance. Image guided radiotherapy using CBCT allows visualization of soft tissue targets and critical structures prior to treatment. Dose escalation is made possible by accurately localizing the target volume while reducing normal tissue toxicity. The kilovoltage x-rays of the cone beam imaging system contribute additional dose to the patient. In this study a 2D reference radiochromic film dosimetry method employing GAFCHROMICTM model XR-QA film is used to measure point skin doses and dose profiles from the Elekta XVI CBCT system integrated onto the Synergy linac. The soft tissue contrast of the daily CBCT images makes adaptive radiotherapy possible in the clinic. In order to track dose to the patient or utilize on-line replanning for adaptive radiotherapy the CBCT images must be used to calculate dose. A Hounsfield unit calibration method for scatter correction is investigated for heterogeneity corrected dose calculation in CBCT images. Three Hounsfield unit to density calibration tables are used for each of four cases including patients and an anthropomorphic phantom, and the calculated dose from each is compared to results from the clinical standard fan beam CT. The dose from the scan acquisition is reported and the effect of scan geometry and total output of the x-ray tube on dose magnitude and distribution is shown. The ability to calculate dose with CBCT is shown to improve with the use of patient specific density tables for scatter correction, and for high beam energies the calculated dose agreement is within 1%.
La tomographie par faisceaux conique (CBCT) informatisée a été récemment développée en radiothérapie pour l'utilisation de guidage par imagerie. La radiothérapie guidée par imagerie (IGRT) utilisant le CBCT, permet la visualisation des cibles à tissus mous et des structures critiques avant le traitement. En localisant précisément la cible, une « escalade » de dose est rendue possible et la toxicité des tissus sains est réduite. Les rayons-X à basse énergie (kilovoltage) du system d'imagerie du CBCT, contribue à une dose additionnelle pour le patient. Dans cette étude, une méthode dosimétrique utilisant un film 2D radiochromic (Gafchromic film, model XR-QA) a été employé pour mesurer des points de dose à la peau ainsi que des profiles de dose. Cette étude a été réalisée à l'aide d'un system d'Elekta XVI CBCT installé sur un accélérateur linéaire du Synergy. Le contraste des images quotidiennes du CBCT des tissus mous rend possible au niveau clinique l'utilisation de la radiothérapie adaptive. Dans le but de suivre la dose administrée au patient ou utiliser de la replanification en ligne pour la radiothérapie adaptive, les images CBCT doivent être utilisées pour le calcul de dose. Une calibration des unités de Hounsfield par méthode de correction de dispersion est examinée dans le cas de dose calculée dans des milieux hétérogènes pour les images CBCT. Trois unités de Hounsfield par table de calibration de densité sont utilisées pour chaque des quatre cas incluant des patients et un fantôme anthropomorphique. Le calcul de dose pour chaque cas est comparé avec les résultats cliniques standards de tomographie par faisceaux en éventail. La dose acquise avec le scanner est reportée et l'effet géométrique du scanner ainsi que le débit total du tube a rayon-X sur la magnitude et la distribution de la dose sont montrés. La capacité de calculer la dose avec un CBCT est présentée dans le but d'amélio

APA, Harvard, Vancouver, ISO, and other styles

4

Anamali, Sindhura. "Prevalence of the posterior superior alveolar canal assessed with cone beam computed tomography." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/1425.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Allen, Jessica. "Evaluation of Maxillary Molar Furcations, Clinical Measurements versus Cone Beam Computed Tomography." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3407.

Full text

Abstract:

BACKGROUND: The use of three-dimensional imaging has shown to provide advantages to the clinician in assessing bone morphology. The aim of this study will be to compare the diagnostic efficacy of cone beam computed tomography (CBCT) versus diagnostic clinical measurements in patients presenting with furcation involved maxillary first molars. METHODS: The study population included 20 patients with 34 maxillary first molar teeth with furcation involvement. Clinical horizontal and vertical probing measurements were compared to CBCT measurements taken by two calibrated examiners. RESULTS: Horizontal measurements showed a significant difference between Glickman class II and class III. There were no statistical significant differences with the horizontal measurements between clinical probing, bone sounding and CBCT measurements. CBCT vertical measurements were statistically greater than clinical probing measurements. CONCLUSION: The CBCT can provide similar horizontal measurements to standard clinical horizontal probing measurements and will provide a greater vertical dimension of a furcation defect to standard vertical probing measurements.

APA, Harvard, Vancouver, ISO, and other styles

6

Chen, Shufei. "Markerless Lung Tumor Trajectory Estimation from Rotating Cone Beam Computed Tomography Projections." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4439.

Full text

Abstract:

Respiration introduces large tumor motion in the thoracic region which influences treatment outcome for lung cancer patients. Tumor motion management techniques require characterization of temporal tumor motions because tumor motion varies patient to patient, day to day and cycle to cycle. This work develops a markerless algorithm to estimate 3 dimensional (3D) lung-tumor trajectories on free breathing cone beam computed tomography (CBCT) projections, which are 2 dimensional (2D) sequential images rotating about an axis and are used to reconstruct 3D CBCT images. A gold standard tumor trajectory is required to guide the algorithm development and estimate the tumor detection accuracy for markerless tracking algorithms. However, a sufficient strategy to validate markerless tracking algorithms is lacking. A validation framework is developed based on fiducial markers. Markers are segmented and marker trajectories are xiv obtained. The displacement of the tumor to the marker is calculated and added to the segmented marker trajectory to generate reference tumor trajectory. Markerless tumor trajectory estimation (MLTM) algorithm is developed and improved to acquire tumor trajectory with clinical acceptable accuracy for locally advanced lung tumors. The development is separate into two parts. The first part considers none tumor deformation. It investigates shape and appearance of the template, moreover, a constraint method is introduced to narrow down the template matching searching region for more precise matching results. The second part is to accommodate tumor deformation near the end of the treatment. The accuracy of MLTM is calculated and compared against 4D CBCT, which is the current standard of care. In summary, a validation framework based on fiducial markers is successfully built. MLTM is successfully developed with or without the consideration of tumor deformation with promising accuracy. MLTM outperforms 4D CBCT in temporal tumor trajectory estimation.

APA, Harvard, Vancouver, ISO, and other styles

7

Patel, Alpesh. "Sensitivity and Accuracy of Cone Beam Computed Tomography in Diagnosing Osseous Defects at the Mandibular Condyle." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1363606389.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Duggan, Sayward. "Alveolar Ridge Dimension Analysis Following Socket Preservation Using Clinical Assessment and Cone Beam Computed Tomography (CBCT)." VCU Scholars Compass, 2001. http://scholarscompass.vcu.edu/etd/2433.

Full text

Abstract:

AIM: Extraction of a tooth can lead to alveolar ridge resorption which can be minimized by socket preservation. The aim of this study is to analyze vertical and horizontal alveolar ridge dimensions clinically and by CBCT immediately following extraction and 3-4 months following socket preservation. METHODS: The preserved group (P) consisted of 20 patients with1-2 non-molar teeth requiring extraction with socket preservation, while the control group (C) consisted of 5 patients requiring extraction alone. An acrylic stent was fabricated presurgically in order to measure vertical and horizontal ridge dimensions clinically and radiographically immediately following extraction and 3-4 months following socket preservation. RESULTS: Overall, P sites gained ridge height and lost minimal ridge width over 3-4 months, while C sites lost both ridge height and width. Preserved sites in which the teeth were extracted due to caries had the most significant gain in the radiographic vertical occlusal dimension (RVO). Overall, high correlations were found between the clinical and radiographic measurements at the initial surgery and at the 3-4 month follow up. CONCLUSIONS: The preserved group had minimal ridge resorption and more socket bony fill when compared to the non-preserved group 3-4 months following tooth extraction, especially when the tooth was extracted due to caries. Additionally, the CBCT can be a useful diagnostic tool to evaluate socket preservation healing, as it compares well to clinical assessments of socket healing.

APA, Harvard, Vancouver, ISO, and other styles

9

Ljungsell, Emma, and Elin Luoma. "Utvärdering av cone beam computed tomography som metod vid fraktur i övre extremiteter : - En jämförelse mellan modaliteter." Thesis, Hälsohögskolan, Högskolan i Jönköping, HHJ, Avd. för naturvetenskap och biomedicin, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-44642.

Full text

Abstract:

Bakgrund: Cone beam computed tomography (CBCT) är en form av datortomografi vanlig inom odontologi och börjar utnyttjas mer inom ortopedisk diagnostik. Frakturer i övre extremiteter är vanligt förekommande i samband med trauma. Konventionell röntgen är oftast förstahandsmetod men kan inte alltid utesluta scaphoideumfraktur, som obehandlad kan ge allvarliga konsekvenser. Syfte: Syftet är att utvärdera CBCT som metod vid fraktur i övre extremiteter genom att jämföra med andra modaliteter. Metod: Arbetet är en systematisk litteraturstudie. Databaserna Medline, CINAHL och PubMed användes. Endast artiklar publicerade inom de senaste 10 åren inkluderades. Kvalitetsgranskning utfördes med protokoll från Hälsohögskolan i Jönköping. Resultat: 15 artiklar inkluderades i resultatet. Faktorer som identifierades var konkordans, stråldos, bildkvalitet, diagnostisk kvalitet samt patienttolerans och undersökningstid. CBCT hade överlägsen eller likvärdig konkordans. I åtta av nio artiklar visades CBCT ha lägre stråldos än jämförande modalitet. Generellt var bildkvaliteten god för CBCT. Skilda resultat uppkom för diagnostisk förmåga. Patienttoleransen var högre för CBCT än multidetektor-CT (MDCT) gällande tid. Slutsats: CBCT påvisade god bildkvalitet och diagnostisk förmåga till en relativt låg stråldos, samt högre sensitivitet och specificitet än konventionell röntgen. På grund av skillnader i mätinstrument i det insamlade materialet kan ingen definitiv slutsats dras. Vidare studier inom ämnet rekommenderas.
Background: Cone beam computed tomography (CBCT) is a method commonly used in odontology and is becoming more used in orthopedic diagnostics. Fractures in upper extremities are a common occurrence in trauma. Conventional radiography is often the firsthand method but cannot always exclude scaphoid fractures, which untreated can have serious consequences. Purpose: The purpose is to evaluate CBCT as an examination method for fractures in the upper extremities by comparing with other modalities. Method: This study is a systematic literature review. The databases used were Medline, CINAHL and PubMed. Only articles published within the last 10 years were included. A quality audit was implemented using a protocol from Jönköping University. Results: 15 articles were included. The factors identified were observer agreement, radiation dose, image quality, diagnostic quality, patient tolerance and image duration. CBCT had a better or equal observer agreement. In eight out of nine articles, CBCT was shown to have a lower radiation dose than its comparative modality. In general, a good image quality in CBCT was found. Differing results were found about diagnostic ability. The patient tolerance was higher for CBCT than multidetector-CT (MDCT) regarding image duration. Conclusions: CBCT demonstrated a good image quality and diagnostic ability to a relatively low radiation dose, and a higher sensitivity and specificity than conventional radiography. Due to differences in measuring instruments used in the gathered material, no definitive conclusion could be drawn. Further studies in the subject is recommended.

APA, Harvard, Vancouver, ISO, and other styles

10

Dhou, Salam. "IMAGE-BASED RESPIRATORY MOTION EXTRACTION AND RESPIRATION-CORRELATED CONE BEAM CT (4D-CBCT) RECONSTRUCTION." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/496.

Full text

Abstract:

Accounting for respiration motion during imaging helps improve targeting precision in radiation therapy. Respiratory motion can be a major source of error in determining the position of thoracic and upper abdominal tumor targets during radiotherapy. Thus, extracting respiratory motion is a key task in radiation therapy planning. Respiration-correlated or four-dimensional CT (4DCT) imaging techniques have been recently integrated into imaging systems for verifying tumor position during treatment and managing respiration-induced tissue motion. The quality of the 4D reconstructed volumes is highly affected by the respiratory signal extracted and the phase sorting method used. This thesis is divided into two parts. In the first part, two image-based respiratory signal extraction methods are proposed and evaluated. Those methods are able to extract the respiratory signals from CBCT images without using external sources, implanted markers or even dependence on any structure in the images such as the diaphragm. The first method, called Local Intensity Feature Tracking (LIFT), extracts the respiratory signal depending on feature points extracted and tracked through the sequence of projections. The second method, called Intensity Flow Dimensionality Reduction (IFDR), detects the respiration signal by computing the optical flow motion of every pixel in each pair of adjacent projections. Then, the motion variance in the optical flow dataset is extracted using linear and non-linear dimensionality reduction techniques to represent a respiratory signal. Experiments conducted on clinical datasets showed that the respiratory signal was successfully extracted using both proposed methods and it correlates well with standard respiratory signals such as diaphragm position and the internal markers’ signal. In the second part of this thesis, 4D-CBCT reconstruction based on different phase sorting techniques is studied. The quality of the 4D reconstructed images is evaluated and compared for different phase sorting methods such as internal markers, external markers and image-based methods (LIFT and IFDR). Also, a method for generating additional projections to be used in 4D-CBCT reconstruction is proposed to reduce the artifacts that result when reconstructing from an insufficient number of projections. Experimental results showed that the feasibility of the proposed method in recovering the edges and reducing the streak artifacts.

APA, Harvard, Vancouver, ISO, and other styles

11

Campbell, Matthew Stephen. "A Practical Method to Superimpose Sella Turcica in Serial CBCT Images." Master's thesis, Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/470228.

Full text

Abstract:

Oral Biology
M.S.
Introduction: We argue, for studies of growth or treatment changes, superimposed CBCT images ought to be employed routinely. The location of 3D landmarks on curved structures, however, has been complex. In this study, a reliable method of CBCT superimposition was developed with the aid of AMIRA XImage® software. The specific focus was to develop a practical method for cranial base superimpositions at sella turcica in serial CBCT images. Subsequently, evaluations of the anterior curvature of hypophyseal fossa during growth were completed to confirm the stability. Comparisons of surface changes in the superimposed images in different regions were also made. Methods: Samples of pre- and post-orthodontic CBCT data were procured from Case Western Reserve University. Cranial base changes in 10 adolescent patients of Class I and II hypodivergent, normodivergent, and hyperdivergent malocclusions, were observed over an average interval of 2 years and 5 months. Cranial base models were superimposed using a rigid registration technique, and 3D models constructed from manual segmentation in the AMIRA software. Surface distance changes of the entire cranial base were compared to that of the anterior portion of sella turcica. Results: Mean surface distance changes for the entire cranial base and anterior sella were 0.73-1.57 ± 0.71-1.30 mm and 0.37-0.63 ± 0.29-0.43 mm, respectively. The area above a threshold of 0.5 mm was 61.02-74.11% (cranial base) and 40.70-50.94% (anterior sella) as well. Paired t-tests were applied to compare differences between the mean distance and area above the threshold for data of cranial base versus anterior sella. Both illustrated p-values less than 0.0001 and were statistically significant. Intra-rater reliability was evaluated by completing segmentation and registration three consecutive times on each CBCT volume. Mean surface differences were within 0.01 mm with the exception of one patient. In addition, all subjects exhibited less than 1.00% deviation except three patients, which deviated by 1.03%, 1.46%, and 1.64%, respectively. Conclusions: A practical method of superimposition of serial CBCT images was developed. Through production of color maps, the surface distance of the anterior portion of sella turcica was shown to change much less than the clivus and remaining cranial base structures in pre- and post-treatment scans of growing children. Lastly, the method of superimposition developed here may assist future studies of skeletal changes with accuracy.
Temple University--Theses

APA, Harvard, Vancouver, ISO, and other styles

12

Ghowsi, Ali, David Hatcher, Heeyeon Suh, Joorok Park, and Heesoo Oh. "Accuracy and reliability of a fully automated landmark identification system on Cone Beam Computed Tomography." Scholarly Commons, 2021. https://scholarlycommons.pacific.edu/dugoni_etd/17.

Full text

Abstract:

ABSTRACT Introduction: Medical imaging continues to play an increasing role in health care and is an integral part of medicine and dentistry. Recent technological advancements have led to the development of fully automated landmark identification (ALI) systems capable of tracing Cone-Beam Computed Tomography (CBCT). The purpose of this study was to evaluate the accuracy and reliability of an ALI system as a tool for automatic landmark location compared to human judges. Methods: One hundred subjects’ CBCT volumes from multiple imaging centers were traced by two human judges who were calibrated and had an ICC close to 1. Fifty-three landmarks were identified in the x, y, and z coordinate planes using Checkpoint Software (Stratovan Corporation, Davis, CA). The ground truth was created by calculating the mean values of the x, y, and z coordinates for each landmark across both judges’ landmark identification. To evaluate the accuracy of ALI, the mean absolute error at each coordinate and mean error distance (mm) between the human landmark identification (ground truth) and the ALI were determined, and a successful detection rate (SDR) was calculated. Results: Overall, the ALI system was as successful at landmarking as the human judges with the exception of a few landmarks. The mean error distance for all 53 landmarks was 4.04 mm ± 6.5. Forty-nine out of 53 landmarks were located within a mean error of 4mm when the average for the coordinates of human judges was considered as a ground truth. Conclusion: Across all three coordinate planes, 96% of the landmarks had a mean absolute error of less than 4mm when compared to the ground truth. The ALI was more precise than humans when identifying landmarks on the same image at different times. This study demonstrates the promise of ALI in aiding orthodontists with landmark identification on CBCTs in the future.

APA, Harvard, Vancouver, ISO, and other styles

13

Alahmad, Haitham N. "Evaluation of Phantoms Used in Image Quality Performance Testing of Dental Cone Beam Computed Tomography Systems." University of Toledo Health Science Campus / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=mco1438985667.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Jamjoom, Faris Zainalabedeen. "Positional Accuracy of Prosthetic Treatment Plan Incorporation Into Cone-beam Computed Tomography Scans Using Surface Scan Superimposition." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1498241824233391.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Taleb, Mehr Mahdieh. "Usefulness of dental cone beam computed tomography (CBCT) for detetion of the anatomical landmarks of the external, middle and inner ear." Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2643.

Full text

Abstract:

Thesis problem: Cone beam computed tomography (CBCT) can provide images with identical information and considerable dose reduction compared with reasonably low costs compared to multislice computed tomography (MSCT) especially where multiple follow up imaging studies are needed. The purpose of this study was to evaluate the diagnostic usefulness of CBCT, using i-CAT®'s software, for detection of the anatomical landmarks of the external, middle and inner ear to answer this question whether MSCT Can be replaced by dental CBCT for evaluation of the temporal bone. Material and methods: Cone beam computed tomography (CBCT) images of 63 subjects made with the same machine, with unknown clinical histories and no evidence of pathosis on CBCT images, were evaluated by two oral and maxillofacial radiologists retrospectively. Seven anatomical points (scutum, oval window, incudomalleolar joint, the tympanic/horizontal and mastoid/vertical segments of the facial nerve, anterior and posterior crura of stapes) of the right and left temporal bone (total of 120 temporal bones) were evaluated. The results were provided as percentage of the points identified by each radiologist. The intra and inter observer agreement were calculated using kappa statistic. Results: The scutum, the tympanic/horizontal segment of the facial nerve canal and the oval window of the right and left temporal bone of 63 cases (total 126 temporal bones) were visualized by the first observer as well-defined structures in 100%, 96.03% and 100% of the cases, respectively. The tympanic/horizontal segment of the facial nerve canal was visualized as a poorly-defined structure in 2.38 % and could not be identified in 1.59% of the cases. The anterior and posterior crura of stapes, the mastoid/vertical segments of the facial nerve canal and the incudomalleolar joint were visualized as well-defined structures in 24.60%, 53.17%, 99.21% and 57.94% of the cases, as poorly defined structures in 32.54%, 41.27%, 0.79% and 39.68% of the cases respectively. The anterior and posterior crura of stapes, the mastoid/vertical segments of the facial nerve canal and the incudomalleolar joint could not be identified in 42.86%, 5.56%, 0% and 2.38% of the cases respectively. The intra- and inter-observer agreement ranged from strong for tympanic/horizontal and mastoid/vertical segments of the facial nerve canal to poor for the anterior and posterior crura of stapes and also the incudomalleolar joint. Conclusion: The i-CAT CBCT machine is a promising replacement for MSCT in evaluation of the temporal bone where there is no need for evaluation of the anterior and posterior crura of stapes and the incudomalleolar joint which are the smallest anatomical structures in the temporal bone. Other CBCT machines with higher contrast to noise ratio should be evaluated for detection of those anatomical structures since CBCT can reduce the patient dose substantially where multiple follow up CT studied are needed. Key words: Computed tomography; cone beam CT; multislice helical CT; middle ear; inner ear; temporal bone.

APA, Harvard, Vancouver, ISO, and other styles

16

Gianquinto, Jared Robert. "A Method of Superimposition of CBCT Volumes in the Posterior Cranial Base." Master's thesis, Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/210320.

Full text

Abstract:

Oral Biology
M.S.
Three dimensional imaging in the form of Cone Beam Computed Tomography has become prevalent in the field of orthodontics. Analytical methods of resulting volumetric data sets have not kept pace with the technology capable of producing them. Current 3D analysis techniques are largely adaptations of existing 2D methods, offering no clear diagnostic advantage over traditional imaging techniques in light of increased radiation exposure, and cannot be compared with norms generated from 2D image capture sources. In order to study morphology in 3D, data sets must be generated for longitudinal studies and native 3D analytical methods must also be developed. Existing methods of CBCT volume superimposition are cumbersome, involving complex software pipelines and multiple systems to complete the process. The goal of the current study was to develop a reproducible method of CBCT volume superimposition in the posterior cranial base in a single software package, and construct an easy to follow, step-by-step manual to facilitate future studies in craniofacial morphology. Existing anonymized sequential CBCT volumes of three subjects meeting inclusion criteria were obtained from the Kornberg School of Dentistry Department of Radiology. Volumes for each subject were imported into AMIRA software, resampled to a standardized 0.5 mm voxel size and superimposed with a mutual information algorithm. Posterior cranial base surface data was extracted using a semi-automatic technique. Resulting surface distance data was compiled and visualized through application of color maps. A streamlined image processing protocol was produced and documented in a detailed step-by-step manual. Surface distance analysis of serial segmentations was performed to verify reliability of the process. Surface distance deviations greater than 0.5 mm consistently fell below 0.2 percent of the total surface area. Sequential scan superimpositions of all three subjects exhibited mean surface distances of less than 0.15 mm. Two out of three subjects exhibited deviations of greater than 0.5 mm in less than 1 percent of the total surface area, suggesting consistent sub-voxel accuracy of the protocol.
Temple University--Theses

APA, Harvard, Vancouver, ISO, and other styles

17

Wils, Patricia. "Tomographie par rayons X : correction des artefacts liés à la chaîne d'acquisition." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00708545.

Full text

Abstract:

L'imagerie cone-beam computed tomography (CBCT) est une méthodologie de contrôle non destructif permettant l'obtention d'images volumiques d'un objet. Le système d'acquisition se compose d'un tube à rayons X et d'un détecteur plan numérique. La recherche développée dans ce manuscrit se déroule dans le contexte industriel. L'objet est placé sur une platine de rotation et une séquence d'images 2D est acquise. Un algorithme de reconstruction procure des données volumiques de l'atténuation de l'objet. Ces informations permettent de réaliser une étude métrologique et de valider ou non la conformité de la pièce imagée. La qualité de l'image 3D est dégradée par différents artefacts inhérents à la plateforme d'acquisition. L'objectif de cette thèse est de mettre au point une méthode de correction adaptée à une plateforme de micro-tomographie par rayons X d'objets manufacturés poly-matériaux. Le premier chapitre décrit les bases de la physique et de l'algorithmie propres à la technique d'imagerie CBCT par rayons X ainsi que les différents artefacts nuisant à la qualité de l'image finale. Le travail présenté ici se concentre sur deux types d'artefacts en particulier: les rayonnements secondaires issus de l'objet et du détecteur et le durcissement de faisceau. Le second chapitre présente un état de l'art des méthodes visant à corriger le rayonnement secondaire. Afin de quantifier le rayonnement secondaire, un outil de simulation basé sur des techniques de Monte Carlo hybride est développé. Il permet de caractériser le système d'acquisition installé au laboratoire de façon réaliste. Le troisième chapitre détaille la mise en place et la validation de cet outil. Les calculs Monte Carlo étant particulièrement prohibitifs en terme de temps de calcul, des techniques d'optimisation et d'accélération sont décrites. Le comportement du détecteur est étudié avec attention et il s'avère qu'une représentation 2D suffit pour modéliser le rayonnement secondaire. Le modèle de simulation permet une reproduction fidèle des projections acquises avec le système réel. Enfin, le dernier chapitre présente la méthodologie de correction que nous proposons. Une première reconstruction bruitée de l'objet imagé est segmentée afin d'obtenir un modèle voxélisé en densités et en matériaux. L'environnement de simulation fournit alors les projections associées à ce volume. Le volume est corrigé de façon itérative. Des résultats de correction d'images tomographiques expérimentales sont présentés dans le cas d'un objet mono-matériaux et d'un objet poly-matériaux. Notre routine de correction réduit les artefacts de cupping et améliore la description du volume reconstruit.

APA, Harvard, Vancouver, ISO, and other styles

18

Abuhaimed, Abdullah Abdulaziz. "Dosimetric investigations of Kilovoltage Cone Beam Computed Tomography (kV-CBCT) utilized in Image Guided Radiation Therapy (IGRT) using Monte Carlo simulations." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6751/.

Full text

Abstract:

Many studies have shown that the computed tomography dose index (CTDI100) which is considered to be the main dose descriptor for CT dosimetry fails to provide a realistic reflection of the dose involved in cone beam CT (CBCT) scans. The main reason for this failure is that CTDI100 measurements are performed within standard head and body phantoms made of polymethyl methacrylate (PMMA) that are only 150 cm long, which is less than or similar to beam widths used for CBCT scans. Therefore, much of the scatter that would contribute to the dose received by a patient is not recorded. Several practical approaches have been proposed to overcome drawbacks of the CTDI100. The aim of this project was to investigate the various dose indices based on the approaches proposed. The dose indices studied were: (1) CTDIIEC proposed by the International Electrotechnical Commission (IEC) and based on measuring CTDI100 using a reference beam and the application of a correction factor based on free-in-air CTDI measurements, (2) f(0,150) the cumulative dose measured with a small ionization chamber within the standard PMMA phantoms, (3) f100 (150) the cumulative dose measured in the standard PMMA phantoms with a 100 mm pencil ionization chamber, (4) f(0,∞) proposed by the American Association of Physicists in Medicine (AAPM) TG - 111 and similar to f(0,150), but measured in infinitely long phantoms made of PMMA, polyethylene, and water, (5) f100 (∞) similar to f100 (150), but measured in infinitely long phantoms. The project also aimed to facilitate the use of indices defined in long phantoms through the generation of correction factors that could be applied to measurements in standard phantoms. This project was based on the use of the Monte Carlo (MC) technique. MC EGSnrc-based user codes namely BEAMnrc and DOSXYZnrc were used to simulate the On-Board-Imager (OBI) imaging system mounted on a Varian TrueBeam linear accelerator. The MC model was benchmarked against experimental measurements and good agreement shown. PMMA, polyethylene, and water head and body phantoms of various lengths and diameters were simulated including a new polyethylene phantom named ICRU/AAPM phantom made by the International Commission on Radiation Units and Measurements (ICRU) and AAPM. A wide range of beam widths with different beam qualities were employed. Four scanning protocols using two acquisition modes (full and half), employed in routine clinical practice, were utilized. In addition, organ doses resulting from three CBCT scans (head, thorax, and pelvis) were evaluated in terms of absorbed dose to organs and tissues using MC simulations on the International Commission on Radiological Protection (ICRP) 110 adult male and female reference computational phantoms. The suitability of the dose indices for CBCT dosimetry was investigated by taking three factors into consideration: (1) the efficiency of the approach as a dose descriptor to report CTDI∞, which is close to the dose received by body tissues near to the middle of a CBCT scan of a patient, (2) the simplicity of the application of the approach in the clinical environment in terms of availability of the measuring instruments, simplicity of the technique, and the number of the scans required to accomplish a quality assurance (QA) assessment, i.e. the QA time, and (3) the ability of the approach in providing an evaluation of organ doses resulting from CBCT scans. To facilitate the use of long phantoms, the relationship between f(0,150) and f100 (150) measurements obtained within the standard PMMA phantoms and those for f(0,∞) obtained within longer phantoms of different compositions were studied. Considering the three factors for the dose indices investigated, all the dose indices were found to be comparable, but each index has advantages and disadvantages. Overall, f(0,150) was considered to be the most suitable with f100 (150) providing an alternative for wider beams. Therefore, the dose indices f(0,150) followed by f100 (150) are recommended for practical CBCT dosimetry. In addition, a function called Gx(W)100 was proposed for evaluating the cumulative dose in long phantoms, and correction factors were also provided to avoid the use of long phantoms. The Gx(W)100 function did not vary significantly with tube potential, but the tube potential did influence the correction factors. The use of the Gx(W)100 function is recommended for estimation of f(0,∞) values from f100 (150) measurements taken in the standard PMMA phantoms.

APA, Harvard, Vancouver, ISO, and other styles

19

Vijayan, Suvendra. "Reliability of 3D-printed mandibles constructed from CBCT volumes of different voxel sizes." Thesis, University of Iowa, 2018. https://ir.uiowa.edu/etd/6323.

Full text

Abstract:

Objectives: The aim of the current study is to establish the reliability of linear cephalometric measurements made on mandibles and their respective 3D printed models created from different voxel resolutions from a cone beam CT machine. Materials and methods: Ten dry mandibles obtained from the Department of Oral Pathology, Radiology and Medicine at The University of Iowa College Of Dentistry were used for this study. All mandibles were scanned on the i-CAT FLX cone beam CT machine (Imaging Sciences International, LLC, Pennsylvania, USA) using voxel resolutions of .30mm, .25mm and .20 mm in a 16cm x 8cm field of view using 360° rotation. The 3D models were reconstructed and saved as .STL files using 3D Slicer software and send to a 3D printer for printing. Two observers measured the 10 mandibles and 30 3D printed models. The measurement were repeated on 50% of the samples after at least one week interval. Cronbach’s alpha and intraclass correlation coefficient were calculated to measure reliability. Results: Good to excellent interobserver and intraobserver reliability was achieved across most of the measurements. There was no difference in reliability across models made from different voxel sizes. Conclusion: The current study successfully showed that the reliability of measurements made on 3D printed models of dry skull mandibles created using fused deposition modeling technique using images of different voxel sizes from an i-CAT FLX CBCT machine are valid, reproducible, and reliable and can be used for diagnostic and clinical purposes.

APA, Harvard, Vancouver, ISO, and other styles

20

Bhagchandani, Sanjay. "Use of Cone Beam Computed Tomography in the Determination of Mental Foramen Location in Relation to Mandibular 1st and 2nd Premolars." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2165.

Full text

Abstract:

The purpose of this study was to use existing Cone Beam Computer Tomography images to determine the vertical and horizontal location of the mental foramen in relation to the mandibular first and second premolars, as well as the distance in millimeters from the apex of each. The distance from the inferior border of the foramen to the inferior border of the mandible was also recorded. The average distance from the apices of the mandibular first and second premolars to the mental foramen was 7.43mm (SD= 1.97) and 5.30mm (SD=1.65) respectively. The foramen was located 11.44mm (SD=1.49) from the inferior border of the mandible. The foramen was in line with the apex of the mandibular second premolar 41% of the time. The mental foramen was further away from the inferior border of the mandible in males and older patients. Mental foramina seemed to be positioned more apically and distally in older patients.

APA, Harvard, Vancouver, ISO, and other styles

21

Oliveira, Sibele Pereira de. "Avaliação de cáries proximais por meio da microtomografia, tomografia Cone Beam e radiografias digitais." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-19122009-120959/.

Full text

Abstract:

A cárie dentária continua sendo um grande desafio para os Cirurgiões-Dentistas pela dificuldade de diagnóstico, sobretudo em superfícies proximais. Muitos equipamentos se destinam a facilitar o exame do paciente, tendo como principal objetivo o diagnóstico de cáries incipientes. Dentre os exames mais utilizados está a radiografia interproximal associada ao exame clínico. O Sistema Internacional de Avaliação e Detecção de Cáries (ICDAS) vem sendo bem aceito tanto para o uso clínico como para pesquisas in vitro e in vivo, apresentando ótimos resultados. Além da técnica interproximal, a tomografia cone beam (CBCT) vem entrando no cotidiano da Odontologia, mas pouco se sabe sobre o seu desempenho para avaliação de cáries iniciais em superfícies proximais. A microtomografia (CT) é um novo método de avaliação destinado a pequenos espécimes e se assemelha a uma versão em miniatura da tomografia axial computadorizada, gerando imagens na ordem de micrômetros. Este método vem sendo utilização em pesquisas para se avaliar tecidos mineralizados, devido à sua habilidade de aferir com precisão o coeficiente de atenuação linear. O método padrão ouro que define com maior precisão os estágios da cárie é o histológico. Contudo, para sua avaliação é necessário destruir os espécimes. Este trabalho teve por objetivo avaliar o desempenho do método ICDAS, de radiografias digitais pela técnica interproximal, da CBCT e da CT para lesões precoces de cárie, com relação à histologia. Houve correlação entre os dados obtidos com o sistema ICDAS para superfícies proximais e as imagens da CT, no que diz respeito à classificação quanto à profundidade das lesões. A CT tem correlação positiva com a histologia tanto na classificação das lesões como na profundidade, contudo esta relação poderia ser maior se uma melhor resolução fosse conseguida. As radiografias digitais pela técnica interproximal tiveram o melhor desempenho com relação à CT e à histologia, sendo este desempenho muito semelhante ao método clínico ICDAS. A CBCT obteve o pior desempenho, contudo ainda assim houve correlação positiva com a histologia e com a CT. A associação do método clínico ICDAS e as radiografias interproximais digitais tiveram o melhor desempenho com relação à histologia. A grande vantagem da microtomografia quando comparada a outros métodos de avaliação da doença cárie, é a manutenção da integridade dos espécimes, a informação tridimensional e isotrópica, possibilitando o uso dos espécimes em outro momento, sem a perda de eventuais características presentes nos mesmos.
Dental caries is still a great challenge to dentists, manly in proximal surfaces due to its difficult diagnosis. Many types of equipment have been designed to minimize this problem, specially aiming early caries detection. Among all, one of the most used by clinicians is the interproximal radiograph. The International Caries Assessment System (ICDAS) is a clinical evaluation method that is well accepted and used having a good performance not only for in vivo but also for in vitro studies. Cone beam CT (CBCT) is also being assessed in the overall Dentistry, but its performance on early caries detection has not extensively being evaluated. Microtomography (CT) is a new assessment method which is addressed to small specimens and is similar to a miniature version of axial computed tomography, producing images with micrometrical definition. CT is being assessed in dental research to evaluate mineral content of hard tissues, due to its ability to measure precisely the linear attenuation coefficient. The gold standard method to measure early caries lesions is histological method. However, to perform it, its necessary to cut the specimen. This study had the aim to evaluate the ICDAS, digital X-rays with the interproximal technique, CBCT and CT performance for early caries lesions, when compared to histology. ICDAS for proximal surfaces and CT had a positive correlation through the lesions depth. CT had a positive correlation with histology when analyzing lesions depth and the classification relating to the severity of the lesion, although this relation could be better if a better resolution could be achieved. Digital bite-wing radiographs had the best performance among all exams when comparing to CT and histology, similar to what we notice with the ICDAS results. CBCT had the worst results when comparing to CT and histology, but it was still considered a good relation. The best performance was achieved with the association of ICDAS and digital bite-wing radiographs when comparing to histology. The great advantage of CT when compared to other validating methods to evaluate dental caries is that it doesnt destroy the specimens, it gives tridimensional and isotropic information, making possible to use the specimens again, without losing inner properties.

APA, Harvard, Vancouver, ISO, and other styles

22

Fontana, Mathias Pante. "Avaliação da raiz mesiovestibular de primeiros molares superiores para detecção do canal mesiopalatino com o uso da tomografia computadorizada de feixe cônico." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/165134.

Full text

Abstract:

Os molares superiores são um dos grupos dentários que mais recebem tratamentos endodônticos e apresentam grande complexidade anatômica nos seus sistemas de canais radiculares. A presença de um canal mesiopalatino (MP) na raiz mesiovestibular é um achado bastante comum e a sua não detecção está relacionada com um alto índice de insucessos na terapia endodôntica. Recentemente, a tomografia computadorizada de feixe cônico (TCFC) vem ganhando destaque na avaliação do canal MP pela sua capacidade de fornecer informações detalhadas e em três dimensões, sendo considerada o melhor método de imagem para essa investigação in vivo. Desta forma, o objetivo desta tese foi pesquisar a prevalência e simetria do número de canais da raiz mesiovestibular em primeiros molares superiores homólogos, por meio da TCFC, assim como, analisar o uso dos filtros de refinamento de imagem para esta investigação. Para o primeiro objetivo, desenvolveu-se uma pesquisa com 264 pacientes possuindo o primeiro molar superior bilateralmente. Foi encontrada simetria em 78,79% dos pacientes, sendo que o canal MP esteve presente bilateralmente em 67,42%. Do total de 528 dentes avaliados, 78% apresentaram o canal MP não havendo correlação da sua presença com sexo e faixa etária (p > 0,05). Para o segundo objetivo, 30 exames de TCFC foram avaliados com cinco diferentes filtros (Original, Smooth, Sharpen, Sharpen Mild, Angio Sharpen Low e Angio Sharpen High) além das imagens originais (sem filtro). Todos os filtros apresentaram altos índices de acurácia (> 83,3%), sensibilidade (> 90%) e especificidade (> 62%), sem diferença estatística (p > 0,05). Entretanto, quando o nível de certeza foi avaliado, os filtros Angio Sharpen High e Sharpen apresentaram os piores resultados, com diferença significativa para as imagens Originais (p <0,05). Os resultados das pesquisas conduzidas permitem concluir que o canal MP é uma condição altamente prevalente e a sua simetria bilateral é frequente. O emprego de filtros de imagem da TCFC não influenciou a detecção do canal MP, entretanto os filtros de maior realce devem ser evitados pois reduzem a certeza do diagnóstico.
The upper molars are the dental group that most receives endodontic treatments and presents great anatomical complexity of their root canal systems. The presence of a second mesiobuccal canal (MB2) is a common finding and its non-detection is related to a high failure rate in endodontic therapy. Recently, cone-beam computed tomography (CBCT) has been highlighted in the MB2 evaluation for its ability to provide detailed and three-dimensional information, and is considered the best imaging method for such investigation in vivo. Thus, the aim of this thesis was to investigate the prevalence and symmetry of the root canal numbers from the mesiobuccal root of first homologous upper molars, as well as to evaluate the use of CBCT image filters for that purpose. For the first objective, a research was developed with 264 patients having the first upper molar bilaterally. Symmetry was found in 78.79% patients, and the MB2 was bilaterally present in 67.42%. Out the total of 528 teeth evaluated, 78% presented the MB2, with no correlation with sex and age group (p > 0.05). For the second objective, 30 CBCT scans were evaluated with five different filters (Original, Smooth, Sharpen, Sharpen Mild, Angio Sharpen Low and Angio Sharpen High) in addition to the original images (none filter). All filters presented high levels of accuracy (> 83.3%), sensitivity (> 90%) and specificity (> 62%), with no statistical difference (p > 0.05). However, when the level of certainty was evaluated, Angio Sharpen High and Sharpen filters presented the worst results, with significant difference for Original images (p < 0.05). The results of the conducted studies allow us to conclude that the MB2 is a highly prevalent condition and its bilateral simmetry is frequent. The use of CBCT image filters did not influence the MB2 detection, however higher enhancement filters should be avoided because they reduce the certainty of the diagnosis.

APA, Harvard, Vancouver, ISO, and other styles

23

Queiroz, Polyane Mazucatto 1991. "Influência da ferramenta de redução de artefato metálico na qualidade de imagens de TCFC = Influence of metal artefact reduction tool in quality of CBCT images." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290661.

Full text

Abstract:

Orientador: Deborah Queiroz de Freitas França
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-28T02:05:09Z (GMT). No. of bitstreams: 1 Queiroz_PolyaneMazucatto_M.pdf: 2757992 bytes, checksum: 06e73a8b08ccb2c9d71f5790996c28cb (MD5) Previous issue date: 2015
Resumo: Materiais de alta densidade física e alto número atômico quando presentes no objeto escaneado podem resultar em artefato nas imagens tomográficas. O artefato compromete a qualidade da imagem tomográfica, podendo inviabilizar o uso dessa modalidade de diagnóstico. Com este trabalho, teve-se dois objetivos: avaliar a ação da ferramenta de redução de artefato metálico (RAM) nas imagens tomográficas de phantoms com diferentes materiais utilizados na Odontologia (amálgama de prata, guta-percha e liga metálica) e avaliar a influência de diferentes tamanhos de campo de visão (field of view - FOV) e de voxel sobre a ação da ferramenta. Foram confeccionados três phantoms de resina acrílica com amostras dos materiais estudados em seu interior. Os phantoms foram escaneados no tomógrafo do aparelho Picasso Trio® (Vathec, Hwaseong, Coréia do Sul) com diferentes FOVs (120x85 mm, 80x80 mm, 80x50 mm e 50x50 mm) e voxels (0,3 mm e 0,2 mm). Todos os escaneamentos foram realizados duas vezes com cada parâmetro, uma sem ativação e uma com ativação da ferramenta de RAM. As imagens foram avaliadas no programa OnDemand3D (CyberMed, Seul, Coréia do Sul). Foram obtidos valores de média e desvio-padrão do histograma das áreas ao redor das amostras e das áreas-controle e foi calculada a relação contraste-ruído (RCR). Os dados foram submetidos à análise. Observou-se influência positiva da ferramenta nos valores do desvio-padrão das áreas ao redor das amostras dos materiais amálgama de prata e liga metálica. Não houve influência da utilização da ferramenta sobre os valores das médias e valores de RCR. Na presença da ferramenta de RAM, o FOV e o voxel não influenciaram os valores de desvio-padrão das áreas ao redor das amostras. Foi possível concluir que a ferramenta mostrou-se eficaz na redução do artefato gerado pelo amálgama de prata e pela liga metálica; e a ação da ferramenta não é influenciada por diferentes FOVs e voxels, de forma que esses parâmetros podem ser selecionados de acordo com o objetivo do exame, sem haver alterações quando a ferramenta é utilizada
Abstract: High density and high atomic number materials are scanned results in artefact in tomographic image. The artefact compromises the quality of tomographic image, which may make the image useless for the diagnosis. The aim of this study were: to assess the action of metal artefact reduction (MAR) algorithm on tomographic images of phantoms with different materials used in Dentistry (dental amalgam, gutta-percha and dental alloy); to assess the influence of different sizes of field of view (FOV) and voxel on the action of the MAR algorithm. Three phantoms were made of acrylic resin with the dentals materials in their interior. The phantoms were scanned on Picasso Trio® machine (Vathec, Hwaseong, South Korea) with different FOVs (120x85 mm, 80x80 mm, 80x50 mm and 50x50 mm) and voxels (0.3 mm and 0.2 mm). All scans were performed twice with each parameter, without and with activation of the MAR algorithm. The images were evaluated on the OnDemand3D software (CyberMed, Seoul, South Korea). The mean and variation (standard deviation - SD) of greyscale values of the histogram of the areas around samples and control areas were obtained. The contrast-to-noise ratio (CNR) was calculated. Data were statistically analyze. There was positive influence of the algorithm on the SD of the areas around the samples of dental amalgam and dental alloy. There was no influence of the algorithm on the mean of greyscale values and CNR. The FOV and voxel did not influence the SD of the areas around the samples when the MAR algorithm was active. In conclusion, the MAR algorithm showed positive effect in reducing the artefact caused by dental amalgam and dental alloy; its action was not influenced by different FOVs and voxels, so those parameters can be selected according to the examination purpose, as there are no changes in the algorithm use
Mestrado
Radiologia Odontologica
Mestra em Radiologia Odontológica

APA, Harvard, Vancouver, ISO, and other styles

24

Evain, Timothée. "Nouvelles méthodes de segmentation en imagerie tomographique volumique à faisceau conique dentaire." Thesis, Paris, ENST, 2017. http://www.theses.fr/2017ENST0066/document.

Full text

Abstract:

La tomographie à faisceau conique (CBCT) est devenue la modalité de référence pour les praticiens du domaine dentaire. Sa relative nouveauté et ses spécificités impliquent que le domaine du traitement de ces images est peu développé à l’heure actuelle. En partenariat industriel avec Carestream Dental, le premier volet de la thèse a conduit à développer une méthode de segmentation semi-automatique de chaque dent, reposant sur l’utilisation de contraintes de forme et d’intensité, et formulée comme un problème de minimisation d’énergie résolu par coupure de graphe. Les résultats montrent une bonne qualité de segmentation avec un coefficient de Dice moyen de 0, 958. Une application logicielle a été réalisée pour la mise en œuvre de la méthode de segmentation auprès des praticiens, en tenant compte des contraintes techniques et temporelles imposées par le contexte clinique, ainsi que du profil des utilisateurs. Un travail préliminaire d’extension de l’approche par coupure de graphe pour segmenter simultanément plusieurs dents à été réalisé, montrant la nécessité de rendre les contraintes de formes plus adaptées aux images et de modifier la méthode d’optimisation pour atteindre des temps de calcul compatibles avec la pratique clinique. Un second volet prospectif des travaux concerne la constitution d’un modèle structurel de la région maxillo-faciale pour formaliser les connaissances a priori sur les organes et leurs interactions. Ce modèle est un graphe conceptuel où sont représentés les concepts des structures et des relations. En particulier, les relations d’alignement et “le long de” ont été modélisées en 3D dans le cadre des ensembles flous
Cone-Beam computed tomography (CBCT) is the new standard imaging method for dental practitioners. The image processing field of CBCT data is still underdeveloped due to the novelty of the method and its specificities compared to traditional CT. With Carestream Dental as industrial partner, the first part of this work is a new semi-automatic segmentation protocol for teeth, based on shape and intensity constraints, through a graph-cut optimization of an energy formulation. Results show a good quality of segmentation with an average Dice coefficient of 0.958. A fully functional implementation of the algorithm has led to a software available for dentists, taking into account the clinical context leading to temporal and technical difficulties. A preliminary extension to multi-objects segmentation showed the necessity to get more stringent shape constraints as well as a better optimization algorithm to get acceptable computation times. The second part of this thesis, more prospective, is about the creation of a structural model of the maxillo-facial space, to formalize the a priori knowledge on organs and theirs spatial relations. This model is a conceptual graph where structures and relationships are seen as concepts. In particular, the spatial relations “Along” and “Aligned”, modeled in a fuzzy set framework, have been extended to 3D objects

APA, Harvard, Vancouver, ISO, and other styles

25

Gomes, Aline Cristine 1989. "Estudo transversal da condição perirradicular e qualidade do tratamento endodôntico e restaurador em uma população brasileira através de tomografias computadorizadas cone beam : Periapical status and quality of root fillings and coronal restorations in a Brazilian population : a CBCT study." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289735.

Full text

Abstract:

Orientador: Alexandre Augusto Zaia
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-27T02:46:44Z (GMT). No. of bitstreams: 1 Gomes_AlineCristine_M.pdf: 987534 bytes, checksum: ab529af967b95d1c0326fdac44aa289f (MD5) Previous issue date: 2015
Resumo: Este estudo transversal determinou a prevalência de periodontite apical em 1290 dentes tratados endodonticamente em uma população brasileira, assim como as variáveis associadas à saúde perirradicular, através da avaliação de Tomografias Computadorizadas Cone beam (CBCT). As CBCT foram avaliadas quanto à presença ou ausência de periodontite apical, assim como as variáveis: gênero, qualidade do tratamento endodôntico, qualidade do tratamento restaurador, limite apical de obturação e presença ou ausência de pino intraradicular. Os dentes foram considerados saudáveis em 48,83 % dos casos avaliados. O tratamento endodôntico foi adequado em 55,11 % dos dentes. A qualidade do tratamento endodôntico e da restauração coronária influenciaram as condições perirradiculares (P < 0,0001 ), ocorrendo melhor resultado quando ambos os tratamentos foram adequados ( P < 0,01 ), assim como em casos de canais obturados até 0-2 mm do ápice radicular (P = 0,02). Foi encontrada uma prevalência relativamente elevada de periodontite apical na população estudada, o que pode estar relacionado à alta prevalência de tratamentos realizados com qualidade insatisfatória. Além disso, as variáveis qualidade do tratamento endodôntico, qualidade do tratamento restaurador e o limite apical da obturação foram significativamente associadas ao sucesso do tratamento endodontico, demonstrando a natureza multifatorial da periodontite apical
Abstract: This cross-sectional study determined the prevalence of apical periodontitis in 1290 root canal-treated teeth from a Brazilian population, as well as the variables associated with periradicular health, through the evaluation of CT scans Cone beam (CBCT). The CBCT were evaluated concerning presence or absence of apical periodontitis, and also the variables: gender, quality of endodontic treatment and coronal restoration, apical level of filling and presence of post restoration. The teeth were considered healthy in 48.83% of cases evaluated. Only 55.11% of the teeth had endodontic treatment rated as adequate. The quality of both endodontic treatment and coronal restoration were statistically correlated with the presence or absence of apical periodontitis (P<.0001), and the best results occur when both treatments were adequate (P <0.01) as well as in cases filled up to 0-2 mm from the apex (P = 0.02). The data showed relatively high prevalence of apical periodontitis in the study population, which may be related to the high prevalence of treatments performed with unsatisfactory quality. In addition, the variables quality of endodontic treatment, quality of restorative treatment and the apical limit of obturation were significantly associated with the success of endodontic treatment, demonstrating the multifactorial nature of apical periodontitis
Mestrado
Endodontia
Mestra em Clínica Odontológica

APA, Harvard, Vancouver, ISO, and other styles

26

Deegan, Timothy G. "Investigation of fiducial marker and soft-tissue image guidance techniques in prostate radiation therapy." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/82289/4/Timothy_Deegan_Thesis.pdf.

Full text

Abstract:

This thesis examines and compares imaging methods used during the radiotherapy treatment of prostate cancer. The studies found that radiation therapists were able to localise and target the prostate consistently with planar imaging techniques and that the use of small gold markers in the prostate reduced the variation in prostate localisation when using volumetric imaging. It was concluded that larger safety margins are required when using volumetric imaging without gold markers.

APA, Harvard, Vancouver, ISO, and other styles

27

Rosa, Vera Lúcia Mestre. "Cefalostato virtual-posicionamento inicial para a padronização na marcação de pontos craniométricos em imagens obtidas por tomografia computadorizada, para uso em cefalometria." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-19122009-122434/.

Full text

Abstract:

Objetivo: O desenvolvimento da tecnologia em diagnóstico odontológico por imagem através dos Tomógrafos Computadorizados por Feixe Cônico, tornou possível e acessível a avaliação cefalométrica através de reconstruções volumétricas do crânio. Parâmetros baseados em evidências científicas são necessários para implementar o seu uso. Alguns parâmetros utilizados na cefalometria convencional (bidimensional) deverão ser esquecidos, outros deverão ser adaptados, outros, ainda, deverão ser criados. Propomos aqui a criação de um Cefalostato Virtual para orientação do crânio em TC, com a utilização de pontos intracranianos, que são mais estáveis. Também propomos a criação do ponto TS e da linha TS-Pg em substituição ao ponto S e ao eixo Y de crescimento de Downs, respectivamente. Além disso, propomos a linha Ba-Op como referência para casos de assimetria faciais onde não é possível a utilização do plano Horizontal de Frankfurt, em casos, por exemplo, de síndromes que afetem os pontos de referências mais externos. Métodos: 49 crânios pertencentes ao do Museu de Anatomia UNIFESP, foram escaneados em um tomógrafo computadorizado por feixe cônico (TCFC), na clínica ISOOrthographic, São Paulo. As pontuações foram realizadas em dois momentos, com espaçamento de uma semana. Foram calculadas estatisticamente medidas-resumo (média, quartis, mínimo, máximo e desvio padrão). Foram calculadas também as correlações intraclasse e correlações de Pearson entre o Eixo Y (S-Gn) e linha entre os pontos TS e Pg. Resultados: Apesar de se observar uma baixa reprodutibilidade nas coordenadas, para os pontos CE, Pg e Gn, foi observada alta correlação entre as medidas angulares em questão. Para descrever a inclinação do Eixo Y em função da inclinação da Linha TS e Pg adotou-se um modelo de regressão linear simples descrito pela equação abaixo: Ang Sö- Gn = 0,989 Ang TS Pgi i Conclusões: o uso do Cefalostato Virtual na orientação de Crânios em Tomografia Computadorizada é factível e favorece a reprodução do posicionamento craniano; apesar da baixa reprodutibilidade intra observador dos pontos CE, Pg e Gn, novos critérios tridimensionais na definição destes pontos poderiam aumentar a precisão na sua localização; a alta reprodutibilidade intra observador para os pontos Op, TS e N, sugere que os critérios anatômicos próprios das estruturas estudadas favorecem a sua determinação; o ponto TS apresentou maior reprodutibilidade do que o ponto S, embora esta diferença não tenha sido estatisticamente significante, podendo-se substituir o ponto S pelo TS em estudos futuros; existe alta correlação entre a linha entre os pontos TS e Pg e o Eixo Y; a avaliação do comportamento da inclinação da linha orbitomeática (HF) com relação à linha Básio-Opístio sugere que na presença de alterações cranianas este relacionamento propicie auxílio no diagnóstico das alterações craniofaciais.
Objective: The development of new technology in dental diagnosis by cone beam CT (CBCT) image, made possible and accessible the realization of cephalometric evaluation through volumetric reconstructions of the skull. Scientific parameters with evidence-based are needed to implement its use. Some parameters used in conventional cephalometry (2D) maybe need to be forgotten, others should be adapted, and others still to be created. In this research we propose to create a Virtual Cephalostat orientation of the skull in CT, with the intracranial landmarks, because they are more stable. We propose the creation of landmark TS (Tubercle Sella) and the TS-Pg line to replace the landmark S (Sella) and the Y-axis of growth (Downs), respectively. Furthermore, we propose to use the Basion-Opistion line as a reference for cases of craniofacial asymmetry where is not possible to use the Frankfurt horizontal plane, as in some cases of syndromes that affects the most external landmarks. Methods: 49 skulls of Anatomy Museum of UNIFESP Federal University of São Paulo, were scanned in a CBCT. The analyses were performed in 2 stages, within 1-week space. Statistics measurements were calculated (mean, quartiles, minimum, maximum and standard deviation). We also calculated the intraclass correlations (ICC) and the Pearson correlations between the Y axis (S-Gn) and the line between landmarks TS-Pg. Results: Even if there is a low reproducibility in the coordinates for landmarks EC (Ethmoidal Crest), Pg and Gn it was observed a high correlation between the angular measures in question. To describe the inclination of the Y axis according to the slope of the line adopted TS and Pg a simple linear regression model is used, showed by the equation bellow: Ang Sö- Gn = 0,989 Ang TS Pgi i Conclusions: The use of the Virtual Cephalostat in orientation of skulls using CBCT is feasible and facilitates the reproduction of the skull position, despite the low intra observer reproducibility of landmarks EC, Pg and Gn, new 3D criteria in the definition of these landmarks could increase the precision in its location. The high intra observer reproducibility at the landmarks Op, N and TS, suggests that the anatomical criteria themselves promote their reliability; The TS landmark showed a higher reproducibility than the S landmark, even though the difference was not statistically significant, and it should be replaced by the landmark TS in future studies. There is a high correlation between the TS - Pg line and Y-axis. The relationship between the slope of the HF plane and Ba -Op line suggests that in the presence of the alteration of morphology in craniofacial structure, this relationship offer help in the diagnosis of craniofacial changes.

APA, Harvard, Vancouver, ISO, and other styles

28

Silva, Siddhartha Uhrigshardt. "Análise tomográfica quantitativa linear de espessuras ósseas alveolares com vistas ao diagnóstico em ortodontia - Proposta de método." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/23/23151/tde-14092012-162818/.

Full text

Abstract:

O objetivo principal desta pesquisa foi justificar a proposta de utilização de um novo método tomográfico (cone beam) de avaliação das espessuras ósseas alveolares, maxilares e mandibulares, por meio de testes objetivos das Condições de Repetitividade e de Precisão Intermediária associadas à variação intra e interoperadores, e conforme a utilização de programa computacional independente (AutoCAD®) para a realização das medições, aplicadas à sequência do Procedimento Operacional Padrão (POP) definido para este experimento. A Fase I da pesquisa registrou os critérios de obtenção da qualidade final das imagens tomográficas definitivas, a partir de equipamento iCAT® (Imaging Sciences International, Hatfield, Pa), com parâmetros de aquisição de 120KVp, 37,7mA e 26,9s, e considerando FOV cilíndrico de 13cm e matriz de 512x512 pixels. A resolução do voxel foi de 0,25mm; A Fase II registrou os critérios exploratórios relativos às condições operacionais do software de visualização, registro (inspeção e identificação) e medição das grandezas selecionadas. A Fase III registrou a realização dos testes de repetitividade e de reprodutibilidade das medidas. Um total de 72 grandezas lineares foram previamente definidas e metodologicamente testadas em sua qualidade de inspeção, identificação e medição, a partir da avaliação de sete (7) operadores independentes, cinco dos quais eram especialistas e com Mestrado Acadêmico em Ortodontia pela FOUSP e, o outro, especialista em Radiologia Odontológica e Doutor em Diagnóstico Bucal (FOUSP). Os examinadores foram previamente instruídos, calibrados e treinados considerando os requerimentos necessários à execução dos testes propostos. O protocolo de pesquisa foi aprovado pelo Comitê de Ética em Pesquisa da Faculdade de Odontologia da Universidade de São Paulo (Parecer CAAE 0120.0.017.000-11). A análise estatística dependeu da utilização de Modelo de Componentes de Variância (hierárquico), e foram consideradas como fontes de variação: as medidas, efetuadas por um mesmo operador ou por diferentes operadores; a face considerada, vestibular ou lingual/palatina; os locais (três níveis de espessura óssea alveolar) em cada uma das faces e, ainda, os diferentes dentes. Esta análise foi realizada de forma separada para mandíbula e maxila. Valores de p<0,05 indicaram significância estatística. Os resultados indicaram significativa confiabilidade geral no método proposto, considerando a Condição de Repetitividade, com apenas 0,24% da variabilidade maxilar total atribuível a um único operador, e mandibular de 0,53%; e com valores expressivos relativos às incertezas de medida maxilares (0,156mm) e mandibulares (0,091mm), desse modo atestando significativa consistência interna (repetibilidade) do método. Os testes da Condição de Precisão Intermediária também indicaram significativa confiabilidade geral no método proposto, com apenas 1,52% da variabilidade total mandibular atribuível à participação de diversos operadores, e maxilar de 0,25%; e com valores também expressivos relativos às incertezas de medida mandibulares (0,149mm) e maxilares (0,158mm), desse modo atestando significativa condição final de reprodutibilidade. Conclui-se que a utilização de imagens provenientes de tomógrafo iCAT®, conforme indicação de resolução de imagem com voxel de 0,25mm, em humanos vivos e a partir de cortes trans-axiais sistematicamente operacionalizados com auxílio de Software AutoCAD®, propicia a geração de condições metodológicas suficientemente favoráveis à obtenção de mapeamento quantitativo linear de espessuras ósseas alveolares, vestibulares e palatinas/linguais, tanto para a maxila quanto para a mandíbula.
This research aimed to justify the proposed use of a new tomography method (cone beam) in the clinical assessment of alveolar, maxillary and mandibular bone width, through objective tests of the Conditions of Repetitiveness and Intermediate Precision associated with intra- and inter-operator variation, using the independent computer program (AutoCAD®) for the execution of the measurements according to the Standard Operating Procedure (SOP) sequence defined for this experiment. Phase I of the research recorded the criteria for obtaining the final quality of the tomography images, using iCAT® (Imaging Sciences International, Hatfield, Pa, USA) equipment with acquisition parameters 120KVp, 37.7mA, and 26.9s, and considering cilindric field-of-view (FOV) of 13cm and 512x512 pixels matrix. The voxel resolution was 0.25mm. Phase II recorded the exploratory criteria relative to the operational conditions of the visualization software, registry (visual inspection and landmark identification) and measurement of the selected magnitudes. Phase III recorded the tests of repeatability and reproducibility of the measurements. A total of 72 linear magnitudes were previously defined and methodologically tested for their quality of inspection, identification and measurement, based on assessment by seven (7) independent operators, five of whom were specialists, with masters degrees in Orthodontics from FOUSP; and the other, a specialist in Dental Radiology and Doctor of Oral Diagnosis (FOUSP). The examiners were previously instructed, calibrated and trained according to the requirements for performing the proposed tests. The research protocol was approved by the Committee for Ethics in Research of the Faculty of Dentistry at the University of São Paulo (Protocol # 102/11-CAAE 0120.0.017.000-11). Statistical analysis used the (hierarchical) Components of Variation Model, and the sources of variation were considered to be: the measurements, made by the same operator or by different operators; the face considered, whether vestibular or lingual/palatal; the locations (three levels of alveolar bone thickness) in each of the faces and, also, the different teeth. This analysis was carried out separately for the mandible and the maxilla. Values of p<0.05 indicated statistical significance. The results indicated overall significant reliability in the proposed method considering the Condition of Repetitiveness, with only 0.24% of total maxillary, and 0.53% of mandibular, variability attributable to a single operator; and with expressive values relative to measurement uncertainties of maxillary (0.156 mm) and mandibular (0.091mm) averages, thereby attesting to significant internal consistency (\"repeatability\") of the method. Tests for the Condition of Intermediate Precision also indicated overall significant reliability of the proposed method, with only 1.52% total mandibular, and 0.25% maxillary, variability attributable to the participation of the various operators; and, also, with expressive values relative to measurement uncertainties of mandibular (0.149mm) and maxillary (0.158mm) averages, thereby attesting to the significant final condition of reproducibility. It is concluded that the use of images from iCAT® tomography, as indicated by image resolution with voxels of 0.25mm, in live humans and from transaxial cuts performed systematically with the help of AutoCAD® Software, provides methodological conditions sufficiently favorable for obtaining linear quantitative mapping of alveolar, vestibular and palatal/lingual bone thicknesses, for both the maxillary and mandibular dental arches.

APA, Harvard, Vancouver, ISO, and other styles

29

Soares, Maria Rosangela. "Avaliação dosimétrica de protocolos de exame de tomografia computadorizada de feixe cônico." Universidade Federal de Sergipe, 2016. https://ri.ufs.br/handle/riufs/5242.

Full text

Abstract:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This PhD thesis, addresses the issue of evaluation of cone beam computed tomography, CBCT, scanning protocols, was introduced in dental radiology at the end of the 1990s, and it quickly became a fundamental examination for various procedures. Its main characteristic, the difference of medical CT is the beam shape. This study aimed to calculate the absorbed dose in eight tissues / organs of the head and neck, and to estimate the effective dose in 13 protocols and two techniques (stitched FOV e single FOV) of 5 equipment of different manufacturers of cone beam CT. For that purpose, a female anthropomorphic phantom was used, representing a default woman, in which were inserted thermoluminescent dosimeters at several points, representing organs / tissues with weighting values presented in the standard ICRP 103. The results were evaluated by comparing the dose according to the purpose of the tomographic image. Among the results, there is a difference up to 325% in the effective dose in relation to protocols with the same image goal. In relation to the image acquisition technique, the stitched FOV technique resulted in an effective dose of 5.3 times greater than the single FOV technique for protocols with the same image goal. In the individual contribution, the salivary glands are responsible for 31% of the effective dose in CT exams. The remaining tissues have also a significant contribution, 36%. The results drew attention to the need of estimating the effective dose in different equipment and protocols of the market, besides the knowledge of the radiation parameters and equipment manufacturing engineering to obtain the image.
Na presente tese de doutoramento foi abordada a temática da avaliação de protocolos de exame de tomografia computadorizada de feixe cônico - TCFC, que foi iniciada na radiologia odontológica no fim da década de 1990 e rapidamente tornou-se um exame fundamental para diversos procedimentos. Sua principal característica, que a diferencia da tomografia computadorizada médica, é a forma do feixe. Assim, este estudo objetivou calcular a dose absorvida em 8 tecidos/órgãos da cabeça e pescoço e estimar a dose efetiva em 13 protocolos e duas técnicas (stitched FOV e single FOV) de 5 equipamentos diferentes fabricantes de tomografia computadorizada de feixe cônico. Para isto, foi utilizado um simulador antropomórfico feminino, representando uma mulher padrão, onde foram inseridos dosímetros termoluminescentes em diversos pontos, representando órgãos e tecidos com valores de ponderação apresentados na norma ICRP 103. Os resultados foram avaliados, comparando-se a dose de acordo com o objetivo da imagem tomográfica. Dentre os resultados, observou-se uma diferença de até 325 % de dose efetiva em relação a protocolos com o mesmo objetivo de imagem. Em relação à técnica de obtenção de imagem, a técnica stitched FOV resultou em uma dose efetiva até 5,3 vezes maior que a single FOV para protocolos com o mesmo objetivo de imagem. Na contribuição individual, as glândulas salivares são responsáveis por 31% da dose efetiva, nos exames tomográficos. Os tecidos restantes também apresentaram uma contribuição significativa, 36 %. Os resultados apontam a necessidade de se estimar a dose efetiva nos diversos equipamentos e protocolos presentes no mercado, além de conhecer os parâmetros de radiação e a engenharia de fabricação dos equipamentos para a obtenção da imagem.

APA, Harvard, Vancouver, ISO, and other styles

30

Zamora, Martínez Natalia. "Diseño y puesta a punto de un método cefalométrico en 3D para el estudio de la población ortodóncica." Doctoral thesis, Universitat de València, 2011. http://hdl.handle.net/10803/80905.

Full text

Abstract:

Introducción: La introducción de la tomografía computarizada de haz cónico (CBCT) y su aplicación clínica a la imagen craneofacial tridimensional (3D) supone una herramienta diagnóstica esencial para el clínico. Objetivos: 1-Evaluar la reproducibilidad en la localización de puntos cefalométricos pertenecientes a tejidos duros del cráneo sobre imágenes escaneadas con un equipo CBCT 2-Comprobar si los valores de diferentes mediciones de las reconstrucciones 3D del CBCT se pueden comparar a las mediciones realizadas sobre imágenes 2D de la telerradiografía lateral de cráneo y comparar también si existen diferencias entre dos tipos diferentes de software de CBCT. 3-Diseñar un método cefalométrico 3D y determinar tres planos de referencia en cada uno de los ejes del espacio. Aplicar dicho análisis sobre una muestra de pacientes a los que se les ha realizado un CBCT. Material y Método: Se recogió una muestra global de 90 pacientes que tenían realizado un CBCT i-Cat®. 1-Para hallar la reproducibilidad, 15 CBCTs fueron seleccionados. Dos observadores localizaron 41 puntos en 3 ocasiones con el software NemoCeph 3D®. Se calcularon los Coeficientes de Correlación Intraclase (ICC) intra e interexaminador y se hallaron los errores de localización y asociados al método de medida de cada uno de los puntos. 2-Se seleccionaron 8 casos que tenían realizado además del CBCT, una telerradiografía lateral de cráneo convencional. Las telerradiografías se tomaron con el cefalostato Orthophos Plus DS® y se evaluaron con el software Dental Studio NX®, mientras que las reconstrucciones 3D (CBCT) se evaluaron con dos software diferentes, NemoCeph 3D® e InVivo5®. Un observador midió en dos ocasiones 10 medidas angulares y 3 lineales en cada uno de los registros, hallándose las correlaciones entre los tres tipos de métodos. 3-Se diseñó una cefalometría 3D y se empleó la muestra de los 90 CBCT para hallar los valores cefalométricos descriptivos de cada una de las variables creadas en cada una de las áreas de estudio: patrón facial, clase esquelética, relación maxilo-mandibular, medidas transversales, asimetrías, proporción facial y análisis dentoalveolar; mediante el cálculo de medias y desviaciones típicas, así como correlaciones de las diferentes variables entre sí y en función de la edad y del sexo. Resultados: 1-La reproducibilidad en la localización de los puntos cefalométricos para todos los ejes fue elevada (ICC ≥0.9) en las medidas intraobservador e interobservador. Analizando cada uno de los puntos por separado se encontró que el valor promedio de su desviación típica en todos los ejes fue igual a 1.0 mm. 2-No se encontraron diferencias estadísticamente significativas para ninguna de las medidas entre la telerradiografía lateral de cráneo y los CBCT, siendo los niveles de significación para todas las mediciones ICC>0.65. 3-Se ha creado un plano vertical de referencia (Na, S, Ba) así como diversos planos auxiliares y medidas lineales. Se han establecido las medias y desviaciones típicas de cada una de las variables del análisis 3D estudiadas, estableciendo así mismo diferentes correlaciones que nos sirven para la posterior creación de una base de datos. Conclusiones: 1-Se encontró elevada reproducibilidad en la localización de todos los puntos cefalométricos. Los puntos nasion, silla, basion, suturas frontocigomáticas, puntos anteriores de la rama, primer molar superior izquierdo e incisivo superior se pueden considerar como puntos altamente reproducibles para poder ser empleados en los análisis cefalométricos tridimensionales. 2-Es posible emplear la mayor parte de los valores establecidos en 2D para las mediciones 3D. Así mismo, las mediciones 3D no difieren entre NemoCeph 3D e InVivo5®, pudiéndose realizar las mediciones indistintamente en cualquiera de los dos software. 3-Se ha diseñado un método cefalométrico tridimensional dividido por áreas de interés que puede servir como punto de partida para la evaluación y medición de las características craneofaciales de todos aquellos pacientes que precisen como registro diagnóstico un CBCT.
Introduction: Cone Beam Computerized Tomography (CBCT) allows the possibility of modifying some of the diagnostic tools used in orthodontics, such as cephalometry. The aims were 1-To assess intra and inter-observer reliability in the location of anatomical landmarks belonging to hard tissues of the skull in images taken with a CBCT device, 2-To assess whether the values of different measurements taken on 3D reconstructions from CBCT are comparable with those taken on 2D images from conventional lateral cephalometric radiographs (LCR) 3-To introduce planes of reference and create a cephalometric analysis appropriated to the 3D reality. Study design: 90 patients who had a CBCT (i-Cat®) as a diagnostic register were selected. 1-To assess the reproducibility 15 CBCT were analysed. 41 landmarks were defined on the three spatial axes (X,Y,Z) and located by two observers at different times with the NemoCeph 3D® software. 2-To compare 13 measurements between LCR (Orthophos Plus DS®) and CBCT, 8 patients who had both registers were selected. Measurements were done with softwares Dental Studio NX® (LCR), NemoCeph 3D® (CBCT) e InVivo5® (CBCT). 3-To create and evaluate three spatial planes and a 3D analysis divided in different areas of interest, the 90 CBCT were selected. Results: 1- Intra- and inter-examiner reliability was high, both being ICC ≥ 0.99, with the best frequency on axis Z. 2- No statistically significant differences were found for the angular and linear measurements between the LCR and the CBCTs for any measurement being the correlation levels ICC<0.65. 3- Mean values, standard deviations and correlations of each one of the measurements defined on the 3D analysis were evaluated for all patients. Conclusions: 1-High reliability was found for all the landmarks. The most reliable ones were: Nasion, Sella, Basion, left Porion, point A, anterior nasal spine, Pogonion, Gnathion, Menton, frontozygomatic sutures, first lower molars and upper and lower incisors. 2-No statistically significant differences were found between measurements taken on the LCR and CBCT and in those taken between the two CBCTs. 3-A new 3D analysis has been created and can be applied to measure and evaluate those patients who require a CBCT as a diagnostic register.

APA, Harvard, Vancouver, ISO, and other styles

31

Szathvary, Isacco. "Soft and hard tissues in esthetic implant dentistry: a novel 3D computer-aided approach to dimensional changes evaluation in immediate vs delayed implantation treatment." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3423984.

Full text

Abstract:

Aim of this work is to develop and to validate a structured methodology to investigate the three-dimensional variation that occurs around implants in dentistry. Surgeons need to know in an objective way if what they are doing is correct and if it is the best for the patient. In last decades implantology deeply changed the way to operate of dentists, giving to the patients new opportunities to replace missing teeth. Implantology has known a very big spread all around the world and numbers of patients treated with success is growing year by year. To know exactly what happens around implants is a growing need for clinicians. A standardized method that can investigate in an objective way what soft and hard tissues do around implants doesn’t exist yet. The solutions that researchers used in literature are various and difficult to compare each other. This work after a general discussion that follows the evolution of implantology, wants to investigate some new instruments that could lend to the comparability of results among different studies and finally to give better answers to the clinical questions. Using the method proposed in this work, soft-hard tissue variation are been evaluated from a new prospective that gave impressive results both qualitatively and quantitatively speaking. The procedure is recommended as a new aid in the future studies.
Obiettivo del lavoro è di sviluppare e validare una metodologia strutturata per indagare la variazione tridimensionale che avviene intorno agli impianti endossei in odontoiatria. I chirurghi hanno bisogno di sapere in modo oggettivo se quello che stanno facendo è corretto ed è la migliore terapia per il paziente. Negli ultimi decenni l’implantologia ha profondamente cambiato il modo di operare dei dentisti, dando ai pazienti nuove opportunità per sostituire i denti mancanti. Implantologia ha conosciuto una grande diffusione in tutto il mondo e il numero di pazienti trattati con successo sta crescendo di anno in anno. Sapere esattamente ciò che accade intorno agli impianti è una crescente necessità per i medici. Un metodo standardizzato che possa indagare in modo oggettivo come si modifichino i tessuti duri e molli intorno agli impianti non esiste ancora. Le soluzioni che i ricercatori hanno utilizzato in letteratura sono molteplici e difficili da confrontare tra loro. Questo lavoro, dopo una discussione generale che segue l'evoluzione dell’implantologia, vuole approfondire l’uso di alcuni nuovi strumenti che possano portare alla comparabilità dei risultati tra i diversi studi e, infine, di dare risposte migliori alle domande cliniche che ancora non hanno risposta. Utilizzando il metodo proposto in questo lavoro, è possibile valutare i tessuti peri-implantari da una nuova prospettiva che ha dato risultati impressionanti sia sul versante qualitativo sia su quello quantitativo. La procedura è un ausilio raccomandato come nuovo aiuto nei futuri studi.

APA, Harvard, Vancouver, ISO, and other styles

32

Buscatti, Marcio Yara. "Avaliação da presença de expansão basilar e de septos no seio esfenoidal humano por meio da tomografia computadorizada por feixe cônico." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-04032010-083823/.

Full text

Abstract:

O seio esfenoidal humano, embora sua morfologia seja mais regular quando comparada à dos demais seios paranasais, apresenta numerosas variações anatômicas que afetam sua relação com estruturas vizinhas. Diversos autores mostram a importância do conhecimento dessas variações anatômicas, baseadas tanto na forma quanto na sua presença, para uma correta e segura abordagem cirúrgica nos procedimentos via endoscópica transesfenoidais. Devido a isso, o frequente estudo deste segmento anatômico se torna preponderante e para isso a tomografia computadorizada helicoidal, mais recentemente com o desenvolvimento da aquisição multislice, é de grande importância para o conhecimento tridimensional dos seus aspectos anatômicos e suas estruturas vizinhas, sendo hoje o exame indicado. A tomografia computadorizada por feixe cônico, devido ao baixo custo dos equipamentos e principalmente a baixa dose de radiação, aliada à qualidade e fidelidade de suas imagens, têm ocupado um espaço importante no diagnóstico por imagem nas diferentes especialidades da Odontologia e mostra-se também relevante sua ampliação em outras áreas em função das vantagens já citadas. O objetivo desse estudo, a partir da análise das imagens de 300 pacientes, obtidas em equipamento de tomografia computadorizada por feixe cônico, é mostrar a viabilidade da obtenção das mesmas para a avaliação das variações anatômicas do seio esfenoidal humano, no que se refere à presença e o tipo de expansão basilar e de septos, em um tomógrafo que une qualidade e fidelidade de imagens com baixa dose de radiação. Os resultados mostraram ser viável a observação, por meio da tomografia computadorizada por feixe cônico, tanto da presença de expansão basilar quanto de septos no seio esfenoidal humano, onde 69% dos exames analisados apresentaram expansão basilar e 60% septos. A presença de expansões mostrou ser independente em relação ao gênero e a idade e 81% delas apresentaram-se como críticas. A presença de septos mostrou ser também independente em relação ao gênero, porém associada a pacientes acima de 40 anos, sendo que 36% apresentaram somente o septo principal, 6% septos acessórios e 18% ambos.
The human sinus, although their morphology is more regular when compared to the other paranasal sinuses, has numerous anatomical variations that affect their relationship with neighboring structures. Several authors show the importance of anatomical variations knowledge, based on its shape and occurrence, for a correct and safe surgical approach in the endoscopic transsphenoidal procedures. Due to this, the frequent anatomic study becomes important and the helical CT, most recently with the development of multislice acquisition, is of great importance to the knowledge of their three-dimensional anatomy and its neighboring structures, being nowadays the main indicated survey. The cone beam computed tomography due to the its low cost of equipment and especially the low dose of radiation, combined with quality and fidelity of images, have occupied an important position in diagnostic imaging in the different specialties of Dentistry and shows to be also relevant in others areas according to the advantages already mentioned. This study, based on the analysis of obtained images from 300 patients in cone beam computed tomography equipment, intents the viability of obtaining the evaluation of anatomic variations of sphenoid sinus, in regard to the presence and type of basilar expansion and internal septa, in a CT scanner that combines quality and fidelity of images with low radiation dose. By means of cone-beam computed tomography the results showed the observation to be viable. The presence of basilar sinus expansion and septa in human sphenoid sinus were found. 69% of the analyzed cases showed basilar expansion and 60% the presence of septa. The presence of expansion was independent when considered the gender and age and 81% presented themselves as critical. The presence of septa was independent of gender and associated with patients over 40 years, and 36% had only primary septum, 6% accessories septa and 18% both.

APA, Harvard, Vancouver, ISO, and other styles

33

Boydev, Christine. "Segmentation automatique des images de tomographie conique pour la radiothérapie de la prostate." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0030/document.

Full text

Abstract:

Dans le contexte du traitement du cancer de la prostate, l’utilisation de la tomodensitométrie à faisceau conique (CBCT) pour la radiothérapie guidée par l’image, éventuellement adaptative, présente certaines difficultés en raison du faible contraste et du bruit important dans les images pelviennes. L’objectif principal de cette thèse est d’apporter des contributions méthodologiques pour le recalage automatique entre l’image scanner CT de référence et l’image CBCT acquise le jour du traitement. La première partie de nos contributions concerne le développement d’une stratégie de correction du positionnement du patient à l’aide du recalage rigide (RR) CT/CBCT. Nous avons comparé plusieurs algorithmes entre eux : (a) RR osseux, (b) RR osseux suivi d’un RR local dans une région qui correspond au clinical target volume (CTV) de la prostate dans l’image CT élargie d’une marge allant de 1 à 20 mm. Une analyse statistique complète des résultats quantitatifs et qualitatifs utilisant toute la base de données, composée de 115 images cone beam computed tomography (CBCT) et de 10 images computed tomography (CT) de 10 patients atteints du cancer de la prostate, a été réalisée. Nous avons également défini une nouvelle méthode pratique et automatique pour estimer la distension rectale produite dans le voisinage de la prostate entre l’image CT et l’image CBCT. A l’aide de notre mesure de distension rectale, nous avons évalué l’impact de la distension rectale sur la qualité du RR local et nous avons fourni un moyen de prédire les échecs de recalage. Sur cette base, nous avons élaboré des recommandations concernant l’utilisation du RR automatique pour la localisation de la prostate sur les images CBCT en pratique clinique. La seconde partie de la thèse concerne le développement méthodologique d’une nouvelle méthode combinant le recalage déformable et la segmentation. Pour contourner le problème du faible rapport qualité/bruit dans les images CBCT qui peut induire le processus de recalage en erreur, nous avons imaginé une nouvelle énergie composée de deux termes : un terme de similarité globale (la corrélation croisée normalisée (NCC) a été utilisée, mais tout autre mesure de similarité pourrait être utilisée à la place) et un terme de segmentation qui repose sur une adaptation locale du modèle de l’image homogène par morceaux de Chan-Vese utilisant un contour actif dans l’image CBCT. Notre but principal était d’améliorer la précision du recalage comparé à une énergie constituée de la NCC seule. Notre algorithme de recalage est complètement automatique et accepte comme entrées (1) l’image CT de planification, (2) l’image CBCT du jour et (3) l’image binaire associée à l’image CT et correspondant à l’organe d’intérêt que l’on cherche à segmenter dans l’image CBCT au cours du recalage
The use of CBCT imaging for image-guided radiation therapy (IGRT), and beyond that, image-guided adaptive radiation therapy (IGART), in the context of prostate cancer is challenging due to the poor contrast and high noise in pelvic CBCT images. The principal aim of the thesis is to provide methodological contributions for automatic intra-patient image registration between the planning CT scan and the treatment CBCT scan. The first part of our contributions concerns the development of a CBCT-based prostate setup correction strategy using CT-to-CBCT rigid registration (RR). We established a comparison between different RR algorithms: (a) global RR, (b) bony RR, and (c) bony RR refined by a local RR using the prostate CTV in the CT scan expanded with 1- to-20-mm varying margins. A comprehensive statistical analysis of the quantitative and qualitative results was carried out using the whole dataset composed of 115 daily CBCT scans and 10 planning CT scans from 10 prostate cancer patients. We also defined a novel practical method to automatically estimate rectal distension occurred in the vicinity of the prostate between the CT and the CBCT scans. Using our measure of rectal distension, we evaluated the impact of rectal distension on the quality of local RR and we provided a way to predict registration failure. On this basis, we derived recommendations for clinical practice for the use of automatic RR for prostate localization on CBCT scans. The second part of the thesis provides a methodological development of a new joint segmentation and deformable registration framework. To deal with the poor contrast-to-noise ratio in CBCT images likely to misguide registration, we conceived a new metric (or enery) which included two terms: a global similarity term (the normalized cross correlation (NCC) was used, but any other one could be used instead) and a segmentation term based on a localized adaptation of the piecewise-constant region-based model of Chan-Vese using an evolving contour in the CBCT image. Our principal aim was to improve the accuracy of the registration compared with an ordinary NCC metric. Our registration algorithm is fully automatic and takes as inputs (1) the planning CT image, (2) the daily CBCT image and (3) the binary image associated with the CT image and corresponding to the organ of interest we want to segment in the CBCT image in the course of the registration process

APA, Harvard, Vancouver, ISO, and other styles

34

Guijarro, Martínez Raquel. "Cone-beam computerized tomography (CBCT) evaluation of the upper airway in the context of orthognathic surgery." Doctoral thesis, Universitat Internacional de Catalunya, 2014. http://hdl.handle.net/10803/134767.

Full text

Abstract:

Upper airway analysis has become a key focus of investigation in the fields of Orthognathic Surgery and Orthodontics. This is due to the well-acknowledged relationship between a narrow upper airway and sleep-disordered breathing, and to the association between airway configuration and specific craniofacial phenotypes. As a result of the advancement of the skeletal insertions of the suprahyoid and velopharyngeal muscles, maxillomandibular advancement with counterclockwise rotation has established itself as an effective strategy to increase the pharyngeal airway volume, with subsequent improvement in sleep-disordered breathing symptomatology. These changes can be assessed objectively with cone-beam computerized tomography (CBCT), which has provided a paradigm shift in cranio-maxillofacial imaging due to its capacity to obtain a thorough two- and three-dimensional evaluation of the upper airway at relatively modest costs, with greater accessibility, lower radiation, and shorter scanning times. The most important contributions of this PhD Thesis are the following: 1) Paper one provides the first systematic review of the literature concerning upper airway imaging and analysis with CBCT. Results confirm that CBCT is indeed an accurate and reliable tool for upper airway analysis. Nevertheless, specific problems related to the image acquisition process and to image processing and analysis persist. 2) Paper two is a preliminary CBCT evaluation of the effect of mono- and bimaxillary advancement on the volume of the upper airway. Results showed a systematic volumetric increase for all groups. However, bimaxillary and mandibular advancement achieved a greater percentage increase than maxillary advancement alone. These results suggest the influence of mandibular advancement on the posterior airway space’s dimensions is greater than the effect of the forward movement of the maxilla. 3) Based on the results of the previous two papers, paper three was aimed at providing clinical three-dimensional anatomical limits for the upper airway subregions, translating them into accurate and reliable cephalometric landmarks in CBCT data, and validating the proposed measuring protocol. Our proposed protocol for upper airway subregion analysis proved to be anatomically logical, technically feasible, and statistically reliable.

APA, Harvard, Vancouver, ISO, and other styles

35

Amor, Zaineb. "Bone segmentation and extrapolation in Cone-Beam Computed Tomography." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279802.

Full text

Abstract:

This work was done within the French R&D center of GE Medical Systems and focused on two main tasks: skull bone segmentation on 3D Cone-Beam Computed Tomography (CBCT) data and skull volumetric shape extrapolation on 3D CBCT data using deep learning approaches. The motivation behind the first task is that it would allow interventional radiologists to visualize only the vessels directly without adding workflow to their procedures and exposing the patients to extra radiations. The motivation behind the second task is that it would help understand and eventually correct some artifacts related to partial volumes. The skull segmentation labels were prepared while taking into ac- count imaging-modality related considerations and anatomy-related considerations. The architecture that was chosen for the segmentation task was chosen after experimenting with three different networks, the hyperparameters were also optimized. The second task explored the feasability of extrapolating the volumetric shape of the skull outside of the field of view with limited data. At first, a simple convolutional autoencoder architecture was explored, then, adversarial training was added. Adversarial training did not improve the performances considerably.
I detta arbete undersöktes två huvuduppgifter, skallbenssegmentering på 3D CBCT-data och extrapolering av skallvolumetrisk form på 3D CBCT-data. För båda uppgifterna användes djupinlärningsmetoder. Den första uppgiften är användbar eftersom den skulle göra det möjligt för interventionsradiologer att endast visualisera blodkärlen direkt utan att lägga till arbetsflöde i sina procedurer. För att förbereda uppgifterna tog vi hänsyn till avbildningsmodalitetsrelaterade faktorer och anatomirelaterade faktorer. Arkiekturen för denna uppgift valdes efter experiment med tre olika nätverk, hyperparametrarna optimerades också. Den andra uppgiften undersökte möjligheten att extrapolera den volumetriska formen på skallen utanför synfältet med begränsade data. Denna uppgift är viktig eftersom den möjliggör korrigering av specifika artefakter kopplade till partiella volymer. I början undersöktes en enkel autoencoder-arkitektur, därefter tillkom adversarial training vilket inte avsevärt förbättrade prestandan.

APA, Harvard, Vancouver, ISO, and other styles

36

Paredes, de Sousa Gil Ariane. "CBCT (cone-beam computerized tomography) evaluation of the nasolabial soft tissue effects of Le Fort I maxillary osteotomy." Doctoral thesis, Universitat Internacional de Catalunya, 2019. http://hdl.handle.net/10803/667624.

Full text

Abstract:

The aim of this study is to verify the soft tissues changes in the nasolabial area after Le Fort I osteotomy using a cone-beam computed tomography (CBCT) evaluation of three- dimensional (3D) volume surfaces in preoperative, early postoperative (1 month) and late postoperative (1 year) periods. Many authors have described the undesired soft tissue changes following the Le Fort I osteotomy, as well as many different techniques to prevent and control these changes. However, few studies have attempted to perform a 3D analysis of the nasolabial complex. The subsequent lack of standardized measuring method hinder the performance of comparisons among studies. By doing a systematic review of the literature in this topic, our objective is to list the main adverse effects associated to Le Fort I osteotomy and to list the most effective available techniques of alar dimension control. A specific technique of alar cinch suture will be described and further analyzed whether it is effective or not in controlling alar base widening. To this effect, a clinical retrospective research will be performed in 80 patients who have undergone a Le Fort I osteotomy and received the aforementioned alar cinch suture technique. All patients were operated by the same surgeon (FHA) at Instituto Maxilofacial – Teknon Medical Center - Barcelona. All the data regarding the selected patients will be anonymized, analyzed and measured by the same observer (APSG) and supervised by the same investigator (RGM). The CBCT volumes of these patients will be superimposed and measured in three different periods of treatment using the Dolphin® Orthognathic Surgery Planning software. A specific protocol to superimpose the 3D images using the Voxel Based Registration (VBR) is going to be developed and validated. At the Instituto Maxilofacial, CBCT acquisition is part of the routine diagnostic protocol of every patient undergoing orthognathic procedures. The study can be performed without modifications in this protocol.

APA, Harvard, Vancouver, ISO, and other styles

37

Markwell, Timothy S. "MegaVoltage Cone Beam Computed Tomography with a standard medical linear accelerator." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/87438/1/Timothy_Markwell_Thesis.pdf.

Full text

Abstract:

Accurate patient positioning is vital for improved clinical outcomes for cancer treatments using radiotherapy. This project has developed Mega Voltage Cone Beam CT using a standard medical linear accelerator to allow 3D imaging of the patient position at treatment time with no additional hardware required. Providing 3D imaging functionality at no further cost allows enhanced patient position verification on older linear accelerators and in developing countries where access to new technology is limited.

APA, Harvard, Vancouver, ISO, and other styles

38

Chilà, Deborah. "Dose tracking in radiation oncology using daily CBCT: effects of physical parameters on dose calculation accuracy." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20587/.

Full text

Abstract:

The availability of cone beam computerized tomography (CBCT) images at the time of treatment has opened possibilities for recalculations and tracking of the delivered dose, becoming an effective tool for adaptive radiotherapy. A significant component in the accuracy of dose recalculation on CBCT images is the calibration of the Hounsfield units (HU) to density. The aim of this thesis, developed at the Policlinic of Modena, is to assert a methodology for the characterization of the HU-to-density calibration curve, and to evaluate the impact of the calibration phantom inserts composition and phantom volume on dose calculation accuracy. The HU-to-density calibration curves from four different phantoms were measured and compared. The HU output of a kV CBCT scan depends on the physical parameters of the phantom density inserts, with particular reference to the atomic number (Z), due to the photoelectric effect which is the main radiation-matter interaction at kV energies. The phantom radial diameter also influences the HU values on the image. The effect of scattering and beam hardening was examined as a function of phantom diameter, founding a high deviation on the HU value of the same density insert when varying the radial diameter of the phantom, especially for high densities. When we are dealing with CBCTs also the acquisition parameters influence the resulting image, that’s why we will show that a protocol-specific calibration curve is needed. The resulting calibration curves were used to compare the calculated doses against planned ones. The percent difference between recalculated and planned dose was obtained for chosen clinically important dose levels and a box plot analysis was conducted. Results show that the best calibration curve for dose recalculation on CBCT images has been obtained when a human-tissue-equivalent inserts are used and when the radial diameter of the phantom is close to the dimensions of the real patient.

APA, Harvard, Vancouver, ISO, and other styles

39

Patel, Neepa. "A cone-beam computerized tomography evaluation of anterior root resorption comparing SureSmile® and conventional edgewise treatments." Oklahoma City : [s.n.], 2009.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

40

Malusek, Alexandr. "Calculation of scatter in cone beam CT : Steps towards a virtual tomograph." Doctoral thesis, Linköping : Department of Medical and Health Sciences, Linköping University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11275.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Barallat, Sendagorta Lucía. "Histologic and radiographic evaluation of different bone grafts in ridge preservation procedures." Doctoral thesis, Universitat Internacional de Catalunya, 2016. http://hdl.handle.net/10803/392633.

Full text

Abstract:

The main goal of this PhD project was to better understand how different types of bone grafts behave in ridge preservation procedures. There is clear evidence that, after tooth removal, a healing process takes place in which the blood clot that fills the socket is gradually substituted with new bone. This process is accompanied by a reduction in height and width of the alveolar ridge. These events may result in limited bone availability, which may compromise an adequate implant placement in order to replace the missing teeth. For this reason, the insertion of different graft materials into the extraction socket has been reported. From the available evidence, it may be concluded that ridge preservation procedures do not completely prevent, but minimize loss of horizontal and vertical ridge alterations. From an histological point of view, several studies have analyzed the histological composition of previously preserved areas in order to determine the amount of vital bone formed. Since the additional benefits of different graft materials in terms of newly formed bone compared to natural healing of the extraction socket was still unknown, we conducted a systematic review in order to answer this question. Calcium sulfate, magnesium enriched hydroxyapatite (MHA) and porcine-derived bone grafts resulted in a significant greater amount of newly formed bone than natural healing sites. Studies evaluating allografts, autologous bone and bioactive glass showed no statistical significant differences between treatment groups. Due to the great variability of the included studies, no firm conclusions could be drawn. Demineralized bovine bone mineral (DBBM) and demineralized bone bovine mineral embedded in 10% collagen matrix (DBBM-C) have been widely used in regenerative therapies and particularly in ridge preservation procedures. However, the possible differences between both grafting materials had not previously been analysed. Therefore, a double blind randomized clinical trial comparing DBBM and DBBM-C in ridge preservation procedures was conducted. A reduction in height and width was observed 5 months after tooth extraction in sites preserved either with DBBM or DBBM-C, but no significant differences were encountered between treatment groups. On the other hand, the histomorphometric analysis resulted in a similar composition in terms of new bone formation, non-mineralized connective tissue and residual graft particles in both treatment groups. From the above mentioned research projects it may be concluded that there is no consensus on which graft material offers the best outcomes from an histological point of view. More specifically, the results of the randomized clinical trial suggest that there are no statistically significant differences between DBBM and DBBM-C neither in height and width reduction of the alveolar ridge nor in their histological composition after a healing period of 5 months.
El objetivo final de este proyecto de tesis doctoral era conocer mejor el comportamiento de distintos materiales de injerto en la técnica de preservación alveolar. Hay evidencia de que, después de la extracción dental, comienza un proceso de cicatrización durante el cual el coágulo sanguíneo es progresivamente reemplazado por hueso nuevo. Además, se produce una reducción en altura y anchura de la cresta alveolar, que puede a su vez dar lugar a una disponibilidad ósea limitada pudiendo comprometer la posterior colocación de implantes. Por este motivo, se ha propuesto la introducción de distintos materiales de injerto en el alveolo postextracción. La literatura científica sugiere que los procedimientos de preservación alveolar minimizan estas alteraciones dimensionales de la cresta en sentido horizontal y vertical . Desde un punto de vista histológico, múltiples estudios han evaluado la composición histológica de áreas donde previamente se había realizado una preservación alveolar para determinar la cantidad y calidad del hueso nuevo formado. Como el beneficio adicional a nivel histológico de la preservación alveolar con distintos materiales de injerto respecto a la cicatrización natural del alveolo postextracción no se conocía, realizamos una revisión sistemática para responder esta cuestión. El sulfato de calcio, la hidroxiapatita enriquecida con magnesio (MHA) y los xenoinjertos de origen porcino resultaron en un porcentaje de hueso nuevo formado significativamente mayor que las áreas control. Otros estudios que utilizaron autoinjertos, aloinjertos o biovidrios no observaron diferencias significativas entre grupos. Sin embargo, debido a la gran variabilidad de los estudios incluídos, no se pudieron sacar conclusiones definitivas. El injerto bovino desproteneizado (DBBM) y el injerto bovino desproteneizado en una matriz de colágeno (DBBM-C) han sido ampliamente utilizados en terapias regenerativas y, particularmente, en preservación alveolar aunque aún no se han analizado las posibles diferencias entre ambos materiales. Por eso se realizó un ensayo clínico randomizado a doble ciego comparando DBBM y DBBM-C en preservación alveolar. Cinco meses después de la extracción, se observó una reducción en anchura y altura de la cresta alveolar en ambos grupos de tratamiento, pero no se encontraron diferencias estadísticamente significativas entre ambos. Por otro lado, el análisis histomorfométrico demostró una composición histológica similar en áreas tratadas con DBBM y áreas tratadas con DBBM-C. De los estudios mencionados previamente, se puede concluir que no hay un consenso sobre qué material de injerto ofrece los mejores resultados en cuanto a composición histológica. Particularmente, los resultados del ensayo clínico randomizado sugieren que no existen diferencias estadísticamente significativas entre DBBM y DBBM-C en cuanto a cambios dimensionales ni en cuanto a composición histológica 5 meses después de realizar la preservación alveolar.

APA, Harvard, Vancouver, ISO, and other styles

42

Meyer, Mark Keith. "Correlating the intra-operative position of the inferior alveolar nerve with pre-operative cone- beam computer tomography in bilateral sagittal split osteotomies." University of the Western Cape, 2015. http://hdl.handle.net/11394/4742.

Full text

Abstract:

Magister Chirurgiae Dentium - MChD
Aim: The aim of the study was to investigate whether a correlation exists between the intra- operative position of the Inferior Alveolar Nerve (IAN) and the nerve position as noted on a pre-operative Cone Beam Computer Tomography (CBCT) scan in patients requiring Bilateral Sagittal Split Osteotomy (BSSO) of the mandible. Introduction: The BSSO of the mandible is of fundamental importance in the correction of dental facial deformities. The main post-operative complication of a BSSO of the mandible is Neurosensory Impairment (NSI). To avoid possible NSI it is important to have as much pre- operative information as possible. In this regard, pre-operative CBCT scans can provide the surgeon with an important assessment of the mandibular canal. This information on the buccolingual, superior and inferior position of the canal, especially in the region of the planned osteotomy, could help the surgical team to avoid IAN injury. Materials and Methods: This study correlates the pre-operative position of the IAN as indicated on a CBCT scan with the intra-operative IAN position in patients requiring BSSO of the mandible. Ten standardised cases were included in a prospective case series where twenty mandibular sides were assessed. Results: The variables assessed in this study were location of the nerve, age, sex, type of movement and side of mandible operated on. It was found that only the distance between the Inferior Alveolar Canal (IAC) and the lower border of the mandible are predictive of whether the IAN will be attached to - or free from - the proximal segment of the mandible. Conclusion: From the study it can be concluded that a CBCT scan is a useful and reliable modality in the pre-operative evaluation of patients undergoing BSSO especially with regard to the assessment and mapping of the mandibular canal.

APA, Harvard, Vancouver, ISO, and other styles

43

Penna, Livia Maria Vieira Rodrigues. "Retratamento endodôntico: casuística e comparação de dois métodos de diagnóstico por imagem." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/25/25147/tde-16082011-091604/.

Full text

Abstract:

O exame radiográfico é um componente de diagnóstico essencial no plano de tratamento de problemas de origem endodôntica. Apesar do desenvolvimento técnico-científico da endodontia, o número de retratamentos endodônticos continua elevado. Neste cenário, a tomografia computadorizada de feixe cônico (TCFC) é utilizada para se obter imagens tridimensionais sem distorções de estruturas pertencentes ao complexo dento-maxilo-facial e seus tecidos adjacentes. Frente aos fatos, este estudo teve como objetivos comparar a incidência de retratamento endodôntico nos anos de 1997, 2001 e 2007 de pacientes atendidos nas clínicas de endodontia da FOB. Foi analisado e quantificado o total de casos de retratamento de canais, os grupos de dentes mais envolvidos, sua distribuição segundo o gênero, relacionando-se também os possíveis motivos dessa ocorrência; comparar dois métodos de diagnóstico por imagem em odontologia, a tomografia computadorizada de feixe cônico e a radiografia periapical. A comparação foi realizada por dois EXAMINADORES, um endodontista e outro radiologista, os quais analisaram as 102 imagens geradas dos exames de 41 pacientes com a necessidade de retramento endodôntico. Não houve aumento na incidência nos três períodos estudados; houve predomínio para o sexo feminino; o retratamento ocorreu em maior número para o dente incisivo central superior e como motivo para sua realização, a maior incidência foi para obturação endodôntica aquém do limite CDC. Quanto à comparação dos exames por imagem, a TCFC revelou-se o procedimento de maior concordância de diagnóstico entre os profissionais, fato que aponta tal método relevante na concretização do diagnóstico, localização e reconstrução de imagens de ótima resolução, contribuindo com os profissionais no planejamento e no sucesso terapêutico, diminuindo a possibilidade de falhas e o consequente insucesso do tratamento endodôntico.
The radiographic test is an essential diagnosis component in the treatment of problems of endodontic origin. Despite the technical and scientific developments in endodontics, the number of endodontic retreatment continues high. In this scenario, Computerized Beam Cone Tomography (CBCT) is used to obtain three-dimensional images without distortions of structures belonging to the dentomaxillofacial complex and its adjacent tissues. The CBCT allows a precocious detection of the dimension and extension of periapical and resorptive diseases, even before they appear in periapical radiographs. In face of such facts, this study aimed at comparing the incidence of endodontic retreatment in 1997, 2001 and 2007 in patients assisted at FOBs endodontic clinics. For this end, all cases of root canal retreatment were analyzed and quantified, as well as the group of teeth with higher incidence, the distribution according to gender, including a survey of the possible reasons for such occurrence, compare two methods of diagnosis by image in endodontics, the Computerized Beam Cone Tomography and the periapical radiograph. Such comparison was performed by two examiners, an endodontist and a radiologist, who analyzed the 102 images obtained from 41 cases of endodontic retreatment assisted at FOB between 2008 and 2009. For this comparison, a questionnaire about the main findings detected in the images was used. There was no increase in incidence in the three periods on focus and a higher incidence among females; the tooth with higher incidence for retreatment was the maxillary central incisor. The main reason for retreatment was endodontic restoration beneath cement-dentin-root canal limit. As for the comparison of tests by image, CBCT showed to be the procedure of higher concordance of diagnosis among the professionals, what indicates that this method is relevant in the diagnosis, localization and reconstruction of images of fairly good resolution, helping professionals with therapeutic planning and success, reducing the possibility of errors and the consequent failure of the endodontic treatment.

APA, Harvard, Vancouver, ISO, and other styles

44

Jacome, Victor Roland. "Evaluation of dose and image quality parameters for cone-beam CT localization protocols in radiation therapy." Oklahoma City : [s.n.], 2009.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

45

Berchtold, Thomas E. "Accuracy and reliability of plaster models vs electronic models." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2010. https://www.mhsl.uab.edu/dt/2010m/berchtold.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Düerkop, Andrea Katharina. "Die dentale Volumentomographie in Diagnostik und Nachsorge fibro-ossärer Läsionen." Doctoral thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-82239.

Full text

Abstract:

Die Radiologie fungiert als wesentliches Instrument in der Diagnostik und Nachsorge fibro-ossärer Läsionen (FOL). Hierbei gewinnen überlagerungsfreie, dreidimensionale Aufnahmen aufgrund der im Kopf-Halsbereich vorhandenen hohen Dichte und Vielfalt anatomischer Strukturen und der damit einhergehenden Fülle von Differentialdiagnosen an Bedeutung. Anhand der Studie wurden die röntgenologischen Charakteristika von ossären Dysplasien (OD) und ossifizierenden Fibromen (OF) im dentalen Volumentomogramm herausgestellt, sowie diagnostische und therapeutische Vorteile der dentalen Volumentomographie (DVT) im Vergleich zur Orthopantomographie (OPG) und Computertomographie (CT) ermittelt und gegenübergestellt. Zu diesem Zwecke wurden anhand eines Fragebogens 18 Röntgenbildpaare (OPG-DVT) von FOL durch zehn Betrachter auf (A) deren röntgenologische Eigenschaften sowie Metallartefakte befundet und (B) deren Abbildungsqualität von sehr gut (1) bis schlecht (5) bzw. nicht beurteilbar bewertet. Insgesamt wurden 360 Analysebögen ausgewertet. Entitäts- und röntgentechnikspezifische Unterschiede wurden statistisch ermittelt. Die Abbildungsqualitäten der DVT und CT wurden auf Grundlage einer intensiven Literaturrecherche verglichen. Die Ergebnisse dieser Studie stellten signifikante Unterschiede in den röntgenologischen Eigenschaften von OD und OF heraus. Acht von zehn Strukturen zeigten in den DVT-Aufnahmen eine signifikant bessere Abbildungsqualität im Vergleich zu den OPG-Aufnahmen. Die teilweise gravierenderen Befunde in den DVT-Aufnahmen deuteten auf eine Unterinterpretation dieser Befunde im OPG hin. Die Literaturrecherche zu Gegenüberstellungen der Abbildungsqualitäten in CT und DVT wies nahezu ausnahmslos auf eine Überlegenheit der DVT hin.

APA, Harvard, Vancouver, ISO, and other styles

47

Chen, Mingqing. "Towards 4D MVCBCT for lung tumor treatment." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3276.

Full text

Abstract:

Currently in our clinic, a mega-voltage cone beam computed tomography (MVCBCT) scan is performed before each treatment for patient localization. For non-small cell lung cancer (NSCLC) patients, a strain gauge is used as an external surrogate to indicate tumor motion in both the planning stage and the treatment stage. However, it is likely that the amplitude of tumor motion varies between treatment fractions without a corresponding change in the surrogate signal. Motion amplitude larger than what was planned may underdose the tumor and overexpose normal tissues. The overall objective of this project is to extend the capabilities of MVCBCT for respiratory motion management by taking advantage of 2D projection images. First, a new method was developed to detect ipsi-lateral hemi-diaphragm apex (IHDA) motion along superior-inferior (SI) direction in 3D. Then a respiratory correlated reconstruction method was implemented and verified. This method is able to create MVCBCT volume in the full exhale (FE) and the full inhale (FI) phases, respectively. The diaphragm to tumor motion ratio (DTMR) was derived by quantifying the absolute position of the tumor and IHDA in these two volumes. The DTMR and the extracted IHDA motion were further used to calibrate the strain gauge signal. Second, an organ motion detection approach was developed, in which the detection is converted into an optimal interrelated surface detection problem. The framework was first applied to tumor motion extraction, which enables accurate detection for large tumors (with a diameter not smaller than 1.9cm). The framework was then applied to lung motion extraction and the extracted lung motion model was used to create a series of displacement vector fields for a motion compensated (MC) reconstruction. The accuracy of both tumor extraction and the MC approach was validated, which shows their clinical feasibility. Last but not least, a novel enhancement framework was developed. The aim of this approach is to eliminate the overlapping tissues and organs in the CBCT projection images. Though scattering and noise is the major problem, the proposed method is able to achieve enhanced projection images with a higher contrast to noise ratio (CNR) without compromising detection accuracy on tumors and IHDA.

APA, Harvard, Vancouver, ISO, and other styles

48

Bujtár, P. (Péter). "Biomechanical investigation of the mandible, a related donor site and reconstructions for optimal load-bearing." Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526207414.

Full text

Abstract:

Abstract Biomechanics are especially important when it comes to the lower third of the face which is composed of a single load-bearing structure, the mandible. Implementation of recent developments in image processing, material sciences and computational technology allows the verification of these principles defining the appropriate practice. The studies listed in the thesis, benchmark from the simple to the more complicated mandibular surgical procedures. The aims were to build patient specific, custom made, composite reconstructions using newly learned techniques. Cross-sectional imaging with Cone Beam Computer Tomography was used to build bone models. The mandible at various ages, undergoing minor oral surgery, partial cross-section reduction with or without reinforcements and complete transection were simulated under biting conditions. Industry standard free form modelling, reverse engineering techniques and Finite Element Analysis were used. Internal and external validations of certain modelling elements were introduced. The mandible became stiffer with increasing age. Minimization of the reduction of the main load-bearing structures was noted to be crucial. The External Oblique Ridge was one such a structure. Partial thickness defects were best spanned by Dynamic Compression Plates. If the remaining amount of bone was insufficient or the bone quality was poor then Locking Compression Plates were preferred. Rounding or the use of a stop-hole was recommended to reduce the risk of fracture development especially without additional Prophylactic Internal Fixation. Fixation using a single reconstruction plate with three screws on either side in the four most common segmental defects was sufficient. Locking monocortical screw fixation was superior over non-locking systems. The suitability of CBCT in bone scanning was demonstrated, highlighting the positional dependent differences within the scanned volume. It should be noted that the relevance and validity of such simulations depends on the quality and the setup. In the future, biomechanically customized fixation can complement tissue engineering procedures and regenerative techniques by providing the precise physical dimensions and biomechanical requirements of the planned reconstructions
Abstrakti Biomekaniikan ymmärtäminen on tärkeää kovakudoskirurgiassa. Periaatteet ovat erityisen tärkeitä, kun kyseessä on kasvojen alin kolmannes, joka muodostuu yhdestä kantavasta rakenteesta eli alaleuasta. Viime aikojen kehitys kuvankäsittelyssä, materiaalitieteessä ja tietokoneteknologiassa ovat mahdollistaneet näiden periaatteiden tarkistamisen käytännössä. Tämän opinnäytetyön osatöissä tutkittiin biomekaniikkaa erityyppisissä leikkauksissa. Tavoitteena on rakentaa tulevaisuudessa potilaille mittatilaustyönä erilaisista materiaaleista korjausosia käyttäen hyväksi uusinta tietoa ja tekniikkaa. Leikekuvantamista kuten Multi Detectoria ja viime aikoina kartiokeilatietokonetomografiaa (KKTT) käytettiin luumallien valmistamisessa. Eri-ikäisten alaleukoja, joihin tehtiin pieniä suukirurgisia toimenpiteitä, osaosteomioita vahvistuksen kanssa tai ilman vahvistusta ja täydellisiä alaleuan katkaisuja, simuloitiin kuormitusolosuhteissa. Teollisuudessa standardoitua vapaamuotoista mallinnusta ja käänteistä tekniikkaa sekä Finite Element Analysis-menetemää käytettiin. Mallinnuksessa käytettiin lisäksi sisäistä ja ulkoista validointia. Alaleuka koveni iän myötä. Leuan kestävyyden kannalta oli ratkaisevaa että tärkeisiin kantaviin rakenteisiin puututtiin mahdollisimman vähän. Oblique Ridge oli yksi tällainen rakenne. Osaosteotomioissa paras ratkaisu oli dynaaminen kompressiolevy. Jos jäljelle jäävän luun määrä tai laatu oli heikko niin sitten lukittuvat puristuskompressiolevyt toimivat parhaiten. Luun pyöristäminen tai pysäytysreiän käyttö oli suositeltavaa vähentämään murtumariskiä varsinkin ilman profylaktista kiskotusta. Neljän yleisimmän segmentaalisen defektin kiinnitys yhdellä levyllä ja kolmella ruuvilla levyn molemmin puolin oli riittävä. Lukittuva monokortikaalinen ruuvikiinnitys oli ylivoimainen verrattuna ei-lukittuvaan systeemiin. KKTT osoittautui parhaaksi menetelmäksi alaleuan kuvantamisessa. Kaikki havainnot voivat toimia yleisohjeena kun harjoitellaan edellä mainittuja toimenpiteitä. On huomattava, että tällaisen simulaation merkitys ja todenmukaisuus riippuu sen laadusta ja asennuksesta. Tulevaisuudessa biomekaanisesti tarkkojen mittausten perusteella suunniteltu luun kiinnitys voi palvella kudosteknologian avulla tehtäviä rekonstruktioita antamalla toimenpiteessä tarvittavat tarkat fysikaaliset mitat ja kuormitusarvot

APA, Harvard, Vancouver, ISO, and other styles

49

Oliveira, Ariane de Souza. "Avaliação das alterações volumétricas da cavidade nasal decorrentes da expansão rápida de maxila assistida cirurgicamente /." Araraquara, 2016. http://hdl.handle.net/11449/138574.

Full text

Abstract:

Orientador: Valfrido Antonio Pereira Filho
Banca: Marisa Aparecida Cabrini gabrielli
Banca: Eduardo Sanches Gonçales
Resumo: O objetivo desta pesquisa foi avaliar as alterações volumétricas da cavidade nasal de pacientes diagnosticados com deficiência transversa de maxila submetidos à expansão rápida de maxila assistida cirurgicamente. Foram avaliadas tomografias computadorizadas de feixe cônico de 28 pacientes adultos (17 mulheres e 11 homens), em três períodos distintos, a saber: período pré-operatório imediato (T1), pós-operatório ao final da expansão (T2) e 6 meses após do término da expansão (T3), no qual as imagens, em formato DICOM, foram importadas e reconstruídas por meio do software On Demand 3D, que permitiu a reconstrução multiplanar da região de interesse de maneira padronizada. Para cada imagem do corte gerado, dois examinadores treinados delimitaram manualmente o espaço aéreo nasal, utilizando o software ImageJ. Com base no principio de Cavalieri, a soma de todas as áreas medidas em cada paciente/período foi utilizada para gerar o volume da estrutura avaliada, em milímetros cúbicos. Os dados obtidos foram verificados pelo teste ANOVA e teste de Tukey, com nível de significância de 5%. Concluiu-se que as expansões maxilares cirurgicamente assistida em adultos não promoveram alterações de volume da cavidade nasal.
Abstract: The objective of this study was to evaluate the volumetric changes of the nasal cavity in patients with transverse maxillary deficiency after surgically assisted rapid maxillary expansion. Cone beam tomographic images of 28 adult patients (17 women and 11 men) were evaluated. They were obtained after three different time periods: immediate preoperative period (T1), postoperative after completion of expansion (T2) and 6 months after expansion (T3). The DICOM images were imported and reconstructed through the On Demand 3D software, which allowed standardized multiplanar reconstruction of the interest region. For each image two examiners manually delimited the nasal air space, using the Image J software. Based on the Cavalieri principle, the summation of all measured areas in each patient/period was used to calculate of the volume in cubic millimeters. The data were analysed by the ANOVA and Tukey tests at 5% significance level. It was concluded that surgically assisted maxillary expansion in adults did not promote volume changes of the nasal cavity.
Mestre

APA, Harvard, Vancouver, ISO, and other styles

50

Oliveira, Ariane de Souza [UNESP]. "Avaliação das alterações volumétricas da cavidade nasal decorrentes da expansão rápida de maxila assistida cirurgicamente." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/138574.

Full text

Abstract:

Submitted by ARIANE DE SOUZA OLIVEIRA null (ariane.oliveira.2@hotmail.com) on 2016-05-17T00:24:12Z No. of bitstreams: 1 Dissertação.pdf: 1165162 bytes, checksum: 802092cd564571fefbc1c2524f006e37 (MD5)
Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-05-18T13:10:09Z (GMT) No. of bitstreams: 1 oliveira_as_me_arafo.pdf: 1165162 bytes, checksum: 802092cd564571fefbc1c2524f006e37 (MD5)
Made available in DSpace on 2016-05-18T13:10:09Z (GMT). No. of bitstreams: 1 oliveira_as_me_arafo.pdf: 1165162 bytes, checksum: 802092cd564571fefbc1c2524f006e37 (MD5) Previous issue date: 2016-03-24
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O objetivo desta pesquisa foi avaliar as alterações volumétricas da cavidade nasal de pacientes diagnosticados com deficiência transversa de maxila submetidos à expansão rápida de maxila assistida cirurgicamente. Foram avaliadas tomografias computadorizadas de feixe cônico de 28 pacientes adultos (17 mulheres e 11 homens), em três períodos distintos, a saber: período pré-operatório imediato (T1), pós-operatório ao final da expansão (T2) e 6 meses após do término da expansão (T3), no qual as imagens, em formato DICOM, foram importadas e reconstruídas por meio do software On Demand 3D, que permitiu a reconstrução multiplanar da região de interesse de maneira padronizada. Para cada imagem do corte gerado, dois examinadores treinados delimitaram manualmente o espaço aéreo nasal, utilizando o software ImageJ. Com base no principio de Cavalieri, a soma de todas as áreas medidas em cada paciente/período foi utilizada para gerar o volume da estrutura avaliada, em milímetros cúbicos. Os dados obtidos foram verificados pelo teste ANOVA e teste de Tukey, com nível de significância de 5%. Concluiu-se que as expansões maxilares cirurgicamente assistida em adultos não promoveram alterações de volume da cavidade nasal.
The objective of this study was to evaluate the volumetric changes of the nasal cavity in patients with transverse maxillary deficiency after surgically assisted rapid maxillary expansion. Cone beam tomographic images of 28 adult patients (17 women and 11 men) were evaluated. They were obtained after three different time periods: immediate preoperative period (T1), postoperative after completion of expansion (T2) and 6 months after expansion (T3). The DICOM images were imported and reconstructed through the On Demand 3D software, which allowed standardized multiplanar reconstruction of the interest region. For each image two examiners manually delimited the nasal air space, using the Image J software. Based on the Cavalieri principle, the summation of all measured areas in each patient/period was used to calculate of the volume in cubic millimeters. The data were analysed by the ANOVA and Tukey tests at 5% significance level. It was concluded that surgically assisted maxillary expansion in adults did not promote volume changes of the nasal cavity.
FAPESP: 2014/10239-3

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Cone beam computer tomography CBCT'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles