To see the other types of publications on this topic, follow the link: CT (Computed Tomography); CTDI (Computed Tomography Dose Index); Phantom.
Journal articles on the topic 'CT (Computed Tomography); CTDI (Computed Tomography Dose Index); Phantom'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'CT (Computed Tomography); CTDI (Computed Tomography Dose Index); Phantom.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Akter, Shirin, Rajada Khatun, S. M. Enamul Kabir, et al. "Dosimetric Verification of Computed Tomography (CT) Systems Using CTDI Phantom." Bangladesh Journal of Nuclear Medicine 26, no. 2 (2024): 172–76. http://dx.doi.org/10.3329/bjnm.v26i2.71488.
Full textAbstract:
Background: Computed tomography (CT) is a medical imaging modality that contributes widely over the world for the diagnosis of disease and for treatment planning in the radiotherapy department. The purpose of the study is to measure the accuracy of dose of CT System for quality treatment. Materials and Methods: The study was executed in a 16 slice SOMATOM Emotion CT Scanner of Delta Hospital Ltd. with Tube voltage 130 KV and Tube current 25 mA using Computed Tomography Dose Index (CTDI) phantom (CIRS) of MPD, Atomic Energy Centre, Dhaka. IBA pencil ionization chamber was used to measure the dose at different positions inside the CTDI phantom and data were collected using IBA MagicMax Universal software. The CT radiation doses were estimated using formalisms in the AAPM Report 96 and 111. Results: For the Adult Body Phantom Console displayed dose was 16.03 mGy and estimated dose was found as16.40 mGy. For the Adult Head Phantom, console displayed dose was 32.40 mGy and estimated dose was found as 34.60 mGy. Between the estimated and console displayed doses for Adult Body Phantom and Adult Head Phantom a deviation was realized of 2.3% and 6.8% respectively. Conclusion: Hence CTDI of the above mentioned machine comply with reference value within a tolerance of ± 20 % according to Food and Drug Administration (FDA). Bangladesh J. Nuclear Med. 26(2): 172-176, 2023
2
Kamila, Kamila, Nurbaiti Nurbaiti, Wahyu Hidayat, et al. "Analisis Hubungan Nilai Noise Citra dan Computed Tomography Dose Index (CTDI) Pada Variasi Pitch Protokol CT Abdomen Rutin di RSUD Koja Jakarta Utara." Jurnal Pengawasan Tenaga Nuklir 4, no. 2 (2024): 81–86. https://doi.org/10.53862/jupeten.v4i2.012.
Full textAbstract:
Computed Tomography (CT) has become one of the primary diagnostic methods in modern medicine, allowing detailed and accurate visualization of the internal structures of the human body. In its use, the pitch value can affect the radiation dose received by the patient and the quality of the resulting image. This study aims to analyze the effect of pitch variations on the Computed Tomography Dose Index (CTDI) and image noise in Routine Abdominal CT to achieve the best image quality with minimal patient dose. This research method uses a quantitative design using a 32 cm diameter PMMA water phantom as a model. Eight pitch variations (0.40, 0.55, 0.60, 0.80, 0.90, 1.00, 1.35, and 1.50) were evaluated using a Siemens Somatom Perspective 128 Slice CT-Scan. Data were collected through experiments on the water phantom and analyzed using descriptive analysis, normality tests, and correlation tests. The results showed no significant relationship between CTDI values and image noise with pitch variations. Increasing the pitch value contributed to increasing CTDI but decreased image noise. These results indicate that a pitch of 0.60 has an optimal image noise value and minimal CTDI in the Routine CT Abdomen protocol at RSUD Koja, North Jakarta. This study provides a deeper understanding of the importance of selecting the correct pitch value in minimizing patient radiation dose while maintaining good image quality. The practical implication is using a pitch of 0.60 as the optimal value for the Routine CT Abdomen protocol, which can reduce the risk of excessive radiation exposure to patients. Keywords: CT-Scan, pitch, water phantom, CT Abdomen, noise, computed tomography dose index (CTDI)
3
Adrien, C., C. Le Loirec, S. Dreuil, and J. M. Bordy. "A new Monte Carlo tool for organ dose estimation in computed tomography." Radioprotection 55, no. 2 (2020): 123–34. http://dx.doi.org/10.1051/radiopro/2020006.
Full textAbstract:
The constant increase of computed tomography (CT) exams and their major contribution to the collective dose led to international concerns regarding patient dose in CT imaging. Efforts were made to manage radiation dose in CT, mostly with the use of the CT dose index (CTDI). However CTDI does not give access to organ dose information, while Monte Carlo (MC) simulation can provide it if detailed information of the patient anatomy and the source are available. In this work, the X-ray source and the geometry of the GE VCT Lightspeed 64 were modelled, based both on the manufacturer technical note and some experimental data. Simulated dose values were compared with measurements performed in homogeneous conditions with a pencil chamber and then in CIRS ATOM anthropomorphic phantom using both optically stimulated luminescence dosimeters (OSLD) for point doses and XR-QA Gafchromic® films for relative dose maps. Organ doses were ultimately estimated in the ICRP 110 numerical female phantom and compared to data reported in the literature. Comparison of measured and simulated values show that our tool can be used for a patient specific and organ dose oriented radiation protection tool in CT medical imaging.
4
Lu, Heqing, Xiangqun Ye, Haowei Zhang, and Si Sun. "STUDY ON A SPECIFIC TEST METHOD FOR DOSIMETRIC CHARACTERIZATION OF ULTRA-WIDE DETECTOR COMPUTED TOMOGRAPHY." Radiation Protection Dosimetry 193, no. 1 (2021): 55–65. http://dx.doi.org/10.1093/rpd/ncab021.
Full textAbstract:
Abstract The purpose of this study was to establish a specific test method for dosimetric characterization of wide-beam computed tomography (CT). For a wide beam, the dose distribution curve and the area of the curve were obtained by using pencil-like ionization chamber, a long CT dose profiler probe, a head phantom and a body phantom. The absolute dose conversion coefficient was multiplied to obtain the total integration integral of the absolute dose distribution, and then the computed tomography dose index (CTDI) value under any wide beam condition was obtained by dividing the collimation width. It was calculated that the absolute dose conversion coefficient was 1.135 under the narrow beam of 8 mm. To a 160 mm-wide beam, the value of CTDI was 7.57 mGy/100mAs after normalized in the head 80 kV CT scanning, and it was 9.80 mGy/100mAs after normalized in the body 120 kV CT scanning. The specific test method solves the problem that the previous measurement method underestimates the CTDI value.
5
Mhagama, Allen Nathan. "Is there Correlation between Measured and Console CTDIvol in Multislice CT Scanners?" Journal of Physical Chemistry & Biophysics 12, no. 4 (2022): 8. https://doi.org/10.5281/zenodo.14604365.
Full textAbstract:
This study investigated the relationship between measured and console volume computed tomography dose index (CTDIvol) in multislice CT scanners. The measured CTDI values were determined from kerma length product measured using pencil ionization chamber inserted in the holes of standard CT phantoms with diameters 16 and 32 cm, which respectively mimic adult head and body using the procedures recommended by International Electro-technical Commission. Significantly large deviations were observed between the measured and console CTDIvol values in multislice CT scanners.
6
Utami, Moh Shofi Nur, Nur Asni, Freddy Haryanto, Muharam Budi Laksono, Anggun Yusifa, and Nermina Nermina. "Comparison of CTDIw and Homogeneity Index on CTDI Phantoms." Jurnal Fisika 13, no. 2 (2023): 85–91. http://dx.doi.org/10.15294/jf.v13i2.48397.
Full textAbstract:
The study was conducted to compare the Computed Tomography Dose Index Weighted (CTDIw) value values and homogeneity index on head and body phantoms with tube voltage variations. Two CTDI phantoms are Gammex (Sun Nuclear, Florida, United States) and IBA (IBA Dosimetry, Schwarzenbruck, Germany). The pencil ionization chamber was used for the measurement of CTDI. The measurements were carried out with a Toshiba Alexion 16 MSCT in a single rotation of axial mode with detector position in the phantom’s center, top, bottom, right, and left. Tube voltage values are 80 kVp, 100 kVp, and 120 kVp. Then, the homogeneity test of the phantom was carried out. The homogeneity value was obtained by measuring the average CT number in the image by determining the region of interest (ROI) at positions namely a, b, c, d, and e, In addition the ratio of the two phantoms was also carried out. The ratio was obtained from the difference of the CTDI100 value at the edge to the CTDI100 value at the center of the head and body phantom from Gammex and IBA. The results showed that the CTDIwof the Gammex head phantom are 26.83 mGy (80 kV), 53.32 mGy (100 kV) and 83.32 mGy (120 kV). While the CTDIw of the Gammex body phantom are 11.73 mGy (80 kV), 21.58 mGy (100 kV) and 36.45 mGy (120 kV). In comparison, CTDIw of the IBA head phantom are 27.01 mGy (80 kV), 55.33 mGy (100 kV) and 81.69 mGy (120 kV). While the CTDIw of the IBA body phantom are 11.85 mGy (80 kV), 23.32 mGy (100 kV) and 35.00 mGy (120 kV). The differences in CTDIw of the two phantoms were within (head phantom is 0.18 % – 2.01 %) and (body phantom is 0.13 % – 1.75 %). The difference below 5% with the p-value of the head phantom is 0.87 and body phantom is 0.89 (more than 0.05) indicates that the two phantoms are not significantly different because the two phantoms are made of the same material. The average ratio for the Gammex head phantom is 1.12 – 1.28, while the IBA head phantom is 1.07 – 1.28. Then the average ratio for the Gammex body phantom is 2.03 – 2.56, while for the IBA body phantom is 1.91 – 2.59 which indicates that the head phantom produces a more uniform dose distribution compared to a body phantom. The average homogeneity value of the IBA phantom is 90.52 % and the average homogeneity value of the Gammex phantom is 87.15 % (a difference of around 3.37%). This value shows that Gammex and IBA phantom have fairly good homogeneity
7
Nurhayati, Arry Y., Nia N. Nariswari, B. Rahayuningsih, and Yuda C. Hariadi. "Analisis Variasi Faktor Eksposi dan Ketebalan Irisan Terhadap CTDI dan Kualitas Citra Pada Computed Tomography Scan." BERKALA SAINSTEK 7, no. 1 (2019): 7. http://dx.doi.org/10.19184/bst.v7i1.9913.
Full textAbstract:
CT Scan merupakan alat pencitraan sinar-X yang dipadukan dengan komputer pengolah data sehingga mampu menghasilkan gambar potongan melintang tubuh dan memiliki dosis relatif lebih tinggi, karena berasal dari radiasi primer dan radiasi hambur dari setiap slice. Dosis yang dihasilkan dipengaruhi oleh parameter scan yaitu faktor eksposi (tegangan tabung, arus- waktu rotasi) dan ketebalan irisan. Kuantitas dosis pada pemeriksaan CT Scan digunakan metode Computed Tomography Dose Index (CTDI). Penelitian ini dilakukan untuk mengatahui efek variasi parameter scan terhadap CTDI dan kualitas citra dengan menggunakan phantom. Hasil data yang diperoleh menunjukkan bahwa pada variasi 200 mAs, 120 kV dan 5 mm menghasilkan CTDIvol dan CNR optimum dengan nilai masing-masing 25.8 mGy dan 3.51. Hal ini disebabkan adanya keseimbangan nilai antara faktor eksposi yang tidak memiliki rentang yang terlalu jauh sehingga menghasilkan energi dan kuantitas sinar X yang seimbang dan ketebalan irisan tidak menghasilkan noise tinggi sehingga objek dalam phantom tetap dapat terlihat lebih baik. Kata Kunci: CT Scan, CTDI, CTDIvol, LCR, CNR.
8
Ilham, Ilham, Sri Zelviani, Jumardin Jumardin, and Khaerul Bariah. "ANALISIS NILAI COMPUTED TOMOGRAPHY DOSE INDEX (CTDI) PADA PHANTOM KEPALA DI INSTALASI RADIOLOGI RUMAH SAKIT UMUM DAERAH SAYANG RAKYAT MAKASSAR." JOURNAL ONLINE OF PHYSICS 10, no. 1 (2024): 55–61. https://doi.org/10.22437/jop.v10i1.37149.
Full textAbstract:
This research aims to determine the CTDI value on a CT Scan aircraft using Dose Profiler and to determine the comparison of the CTDI (Computed Tomography Dose Index) value on the surface of each measurement position. The measurement method was carried out by measuring the CT Scan radiation dose with the CTDI value on the phantom using a RaySafe multimeter at a voltage of 130 kV, using a thickness of 10 mm, a time current accuracy of 100 mAs, 200 mAs and 300 mAs. The research results show the dose received on the surface of each type of phantom position with different time current accuracy respectively for a time current of 100 mAs at the center (9.139 mGy), type 1 (9.606 mGy), type 2 (9.170) type 3 (9.221) , and type 4 (9,210). A time current of 200 mAs is found at the center (9,110 mGy), edge 1 (9,578 mGy), edge 2 (9,546 mGy), edge 3 (9,224 mGy), and edge 4 (9,200 mGy). A time current of 300 mAs is found at the center position (18.39 mGy), edge 1 (19.33 mGy), edge 2 (19.18 mGy), edge 3 (18.48 mGy), and 4 (18.51 mGy) . Time-current variations affect the radiation dose that can be received by the phantom and have a linear influence on the CTDIvol value.
9
Choudhary, Neha, Bhupendra Singh Rana, Arvind Shukla, Arun Singh Oinam, Narinder Paul Singh, and Sanjeev Kumar. "PATIENTS DOSE ESTIMATION IN CT EXAMINATIONS USING SIZE SPECIFIC DOSE ESTIMATES." Radiation Protection Dosimetry 184, no. 2 (2018): 256–62. http://dx.doi.org/10.1093/rpd/ncy207.
Full textAbstract:
Abstract The present work reports data of radiation exposure to the patients during head, chest, pelvis and abdomen CT examinations performed on a third-generation 16-slice CT machine. Radiation exposure was estimated using size specific dose estimates (SSDE) method, which takes into account patient’s physical dimensions in phantom measured computed tomography dose index (CTDI) value. The reported median CT dose volume index CTDIvol values in head, chest, pelvis and abdomen examinations were 26.76, 16.27, 29.81 and 14.74 mGy, respectively. The median doses evaluated using SSDE methodology for the above mentioned procedure were 54.1, 23.1, 42.8 and 20.1 mGy, respectively. Our results showed variation in dose values estimated using CTDI and SSDE methods in all examinations. The evaluated SSDE values were also compared to the values derived from data reported by the American Association of Physicist in Medicine (AAPM). SSDE values in present measurements are 4–8% lower than AAPM values. The present results show that CTDI parameters recorded on CT console should not be used to specify patient dose during CT procedures.
10
Aabid, M., S. Semghouli, and A. Choukri. "Assessment of Computed Tomography Dose Index (CTDI) During CT Pelvimetry Using Monte Carlo Simulation." Atom Indonesia 1, no. 1 (2023): 21–25. http://dx.doi.org/10.55981/aij.2023.1214.
Full textAbstract:
A pelvimetry examination is sometimes prescribed to a pregnant woman at the end of her pregnancy in order to assess the dimensions of her pelvis prior to childbirth. This examination has long been performed by using X-ray, but is now increasingly being replaced by CT-scan The objective of this study is to assess the radiation doses received during a practical CT pelvimetry examination performed using a Hitashi Supria 16-slice CT scanner. The radiation doses were estimated using Monte Carlo (MC)-based simulation with GATE code to model the 16-slice CT scanner machine. The GATE code operates using GEANT4 libraries. A polyymethyl metacrylate (PMMA) acrylic phantom of 32 cm diameter was modeled to represent the patient's body. X-ray energy spectrum generated using the SRS-78 spectrum processor was used for simulation. The simulation was executed with the same exposure parameters as the practical CT pelvimetry examination with dose parameters of 1 mGy, 0.9 mGy, and 36.6 mGy.cm, respectively, for the weighted CT dose index (CTDIw), the volume CT dose index (CTDIvol), and dose-length product (DLP). The MC simulation results provide dose parameters of 1.16 mGy, 1.07 mGy, and 43.6 mGy.cm, respectively, for the CTDIw, CTDIvol, and DLP. The differences between the simulation and the practical examination were 16 %, 18 %, and 18 %, respectively. These differences are considered in a quite good agreement. The results were also consistent with other similar studies. This work proves that the Monte Carlo simulation with the GATE code is usable to assess the patient doses during a CT pelvimetry examination.
11
Chantzi, Stefania, Emmanouil Papanastasiou, Christina Athanasopoulou, Elisavet Molyvda-Athanasopoulou, Panagiotis Bamidis, and Anastasios Siountas. "Design of a Monte Carlo model based on dual-source computed tomography (DSCT) scanners for dose and image quality assessment using the Monte Carlo N-Particle (MCNP5) code." Polish Journal of Medical Physics and Engineering 26, no. 1 (2020): 11–20. http://dx.doi.org/10.2478/pjmpe-2020-0002.
Full textAbstract:
AbstractThe purpose of this work was to develop and validate a Monte Carlo model for a Dual Source Computed Tomography (DSCT) scanner based on the Monte Carlo N-particle radiation transport computer code (MCNP5). The geometry of the Siemens Somatom Definition CT scanner was modeled, taking into consideration the x-ray spectrum, bowtie filter, collimator, and detector system. The accuracy of the simulation from the dosimetry point of view was tested by calculating the Computed Tomography Dose Index (CTDI) values. Furthermore, typical quality assurance phantoms were modeled in order to assess the imaging aspects of the simulation. Simulated projection data were processed, using the MATLAB software, in order to reconstruct slices, using a Filtered Back Projection algorithm. CTDI, image noise, CT-number linearity, spatial and low contrast resolution were calculated using the simulated test phantoms. The results were compared using several published values including IMPACT, NIST and actual measurements. Bowtie filter shapes are in agreement with those theoretically expected. Results show that low contrast and spatial resolution are comparable with expected ones, taking into consideration the relatively limited number of events used for the simulation. The differences between simulated and nominal CT-number values were small. The present attempt to simulate a DSCT scanner could provide a powerful tool for dose assessment and support the training of clinical scientists in the imaging performance characteristics of Computed Tomography scanners.
12
Stephanie Santos, Fernanda. "Study of CT Acquisition Protocols Using Two Head Phantoms." Revista Brasileira de Física Médica 17 (June 12, 2023): 706. http://dx.doi.org/10.29384/rbfm.2023.v17.19849001706.
Full textAbstract:
Computed Tomography (CT) scans promote a higher dose deposition than conventional radiology exams. These exams have significantly increased patient and collective doses and have become a global public health concern. There is a great need to improve protocols to seek for lower doses while maintaining the diagnostic image quality. The development of phantoms allows the testing of different acquisition protocols. In this study were tested two cylindrical head phantoms of polymethylmethacrylate (PMMA). One CT head phantom is the head standard test with 16 cm in diameter and the other head phantom developed is smaller at 12 cm in diameter. Both phantoms are 15 cm long. Different acquisition protocols were performed on a Philips CT scanner, Access model with 16 channels. The central slice of the phantoms was irradiated successively and measurements were performed using a pencil ionization chamber to obtain the CT air Kerma indexes in PMMA (Ck,PMMA,100) and CT dose indexes (CTDI). From these results, the CT Dose Index values weighted and volumetric (CTDIw, CTDIvol) were obtained to 10 cm scans of the central region of the head phantoms, in helical mode. The scans were performed using different voltage values (80, 100 and 120 kV) and charge (mA.s). Dose values varied from 5.59 to 21.51 mGy. The highest recorded dose value was 21.51 mGy for the smaller head phantom and 19.25 mGy for the standard head phantom with 120 kV. Considering the generation of images with the same diagnostic objective, the results obtained showed that the volumetric dose index (CTDIvol) presented a higher dose value in the 12 cm diameter phantom. This phantom has smaller volume than the standard head phantom.
13
Terini, Ricardo Andrade, Johnatan Dias Oliveira, and Elisabeth Mateus Yoshimura. "Application of OSL strips in CT dosimetry according to the AAPM methodology." Brazilian Journal of Radiation Sciences 11, no. 2 (2023): 01–10. http://dx.doi.org/10.15392/2319-0612.2023.2259.
Full textAbstract:
Computed tomography (CT) images contribute to high-quality medical diagnosis, but radiation dose can be quite high, requiring accurate assessment. CT dose index (CTDI) was developed for dosimetric purposes, but for scanners operated exclusively in axial mode. Nowadays, CTDI underestimate patient dose in helical CT exams. AAPM report TG111 (2010) suggested a new metric in which the patient's radiation dose is obtained from dose profiles constructed from several measurements made with a small ionization chamber. It is also possible to obtain dose profiles using properly calibrated OSL (optically stimulated luminescence) strips. The main objective of the present work is to contribute to optimizing CT dosimetry, comparing dose profiles obtained with OSL strips with measurements obtained by other authors. In this work, a “pencil” ionization chamber and 20 cm x 0.3 cm OSL strips were X-ray-irradiated, in air and in the holes of two cylindrical CT phantoms, using 100, 120, 140 kV peak voltages, both in lab and in a clinical CT scanner. Irradiated strips were read using an OSL reader built in the GDRFM. OSL profiles were calibrated against ionization chamber. From them, CTDIw and CTDIvol values were determined, differing approximately 3.9% from those of the CT scanner. From the profiles, also the planar equilibrium dose Deq,p (TG111) was evaluated in some CT protocols; Deq,p exceeded the CTDI values from the CT scanner in every case. E.g.: The percentage difference between Deq,p and CTDIvol for the head phantom ranged between 33-25%. Thus, in some cases, it could be advantageous to use calibrated OSL dosimeters instead of ionization chambers to obtain the profiles, saving time, because it is possible to obtain five OSL profiles from a single phantom irradiation.
14
Khoramian, Daryoush, Soroush Sistani, and Peyman Hejazi. "Establishment of diagnostic reference levels arising from common CT examinations in Semnan County, Iran." Polish Journal of Medical Physics and Engineering 25, no. 1 (2019): 51–55. http://dx.doi.org/10.2478/pjmpe-2019-0008.
Full textAbstract:
Abstract Objective: The literature has approved that the use of the concept of diagnostic reference level (DRL) as a part of an optimization process could help to reduce patient doses in diagnostic radiology comprising the Computed Tomography (CT) examinations. There are four public/governmental CT centers in the province (Semnan, Iran) and, to our knowledge, after about 12 years since the launch of the first CT scanner in the province there is no dosimetry information on those CT scanners. The aim of this study was to evaluate CT dose indices with the aim of the establishment of the DRL for head, chest, cervical spine, and abdomen-pelvis examinations. Methods: Scan parameters of 381 patients were collected during two months from 4 CT scanners. The CT dose index (CTDI) was measured using a calibrated ionization chamber on two cylindrical poly methyl methacrylate (PMMA) phantoms. For each sequences, weighted CTDI (CTDIw), volumetric CTDI (CTDIv) and dose length product (DLP) were calculated. The 75th percentile was proposed as the criterion for DRL values. Results: Proposed DRL (CTDIw, CTDIv, DLP) for the head, chest, cervical spine, and abdomen-pelvis were (46.1 mGy, 46.1 mGy, 723 mGy × cm), (13.8 mGy, 12.0 mGy, 377 mGy × cm), (40.0 mGy, 40.0 mGy, 572 mGy × cm) and (14.9 mGy, 12.1 mGy, 524 mGy × cm), respectively. Conclusion: Comparison with the others results from the other countries indicates that the head, chest and abdomen-pelvis scans in our region are lower or in the range of the other studies investigated in terms of dose. In the case of cervical spine scanning it’s necessary to review and regulate scan protocols to reach acceptable dose levels.
15
Tahiri, M., Y. Benameur, M. Mkimel, R. El Baydaoui, and M. R. Mesardi. "Feasibility of size-specific organ-dose estimates based on water equivalent diameter for common head CT examinations: a Monte Carlo study." Journal of Radiological Protection 43, no. 2 (2023): 021503. http://dx.doi.org/10.1088/1361-6498/acc1f0.
Full textAbstract:
Abstract Computed tomography dose index (CTDI) is an unreliable dose estimate outside of the standard CTDI phantom diameters (16 and 32 cm). Size-specific dose estimate (SSDE) for head computed tomography (CT) examination was studied in the American Association of Physicists in Medicine Report 293 to provide SSDE coefficient factors based on water equivalent diameter as size metrics. However, it is limited to one protocol and for a fully irradiated organ. This study aimed to evaluate the dependency of normalized organ dose (ND) on water equivalent diameter as a size metric in three common protocols: routine head, paranasal sinus, and temporal bone. CTDIw measurements were performed for outlined protocols in the Siemens Emotion 16-slice-configuration scanner. Geant4 Application for Tomographic Emission Monte Carlo simulation platform, coupled with ten GSF patient models, was used to estimate organ doses. CT scanner system was modeled. Helical CT scans were simulated using constructor scan parameters and calculated scan lengths of each patient model. Organ doses provided by simulations were normalized to CTDIvol. The water equivalent diameters (D w) of patient models were obtained via relationships between D w and both effective diameter for a sample of patients’ data.NDs received by fully, partially, and non-directly irradiated organs were then reported as a function of D w. For fully irradiated organs, brain (R 2 > 0.92), eyes (R 2 > 0.88), and eye lens (R 2 > 0.89) correlate well with D w. For the rest of the results, a poor correlation was observed. For partially irradiated organs, the exception was scalp (R 2 = 0.93) in temporal bone CT. For non-directly irradiated organs, the exception was thyroid (R 2 > 0.90) and lungs (R 2 > 0.91) in routine head CT. ND correlates well in routine head CT than other protocols. For the most part, no relationship seems to exist between R 2 and scan percentage coverage. The results have revealed additional factors that may influence the ND and D w relationship, which explains the need for more studies in the future to investigate the effect of scan conditions and organ anatomy variation.
16
Song, Hoondong, Hanjoo Jang, and Jongduk Baek. "Standardization of Lung CT Number Using COPD Gene2 Phantom Under Various Scanning Protocols." Sensors 25, no. 9 (2025): 2906. https://doi.org/10.3390/s25092906.
Full textAbstract:
Lung computed tomography (CT) images are widely used to diagnose chronic obstructive pulmonary disease (COPD) by evaluating signs of lung tissue destruction. Accurate diagnosis requires standardizing the CT numbers in lung CT images to distinguish between normal and damaged tissue. The CT number standardization method proposed by Chen-Mayer et al., which uses the linearity of Martinez’s formula, showed promising results in phantom studies. However, our findings reveal that the CT number of water varies significantly, depending on scanning conditions and the characteristics of its container, making it an unreliable reference for lung CT number standardization. To enhance the standardization method, we modified the approach to exclude water and used only solid foams from the COPD gene2 phantom as references. To evaluate the proposed method, we collected 234 CT images of the COPD gene2 phantom from 8 different CT scanners and assessed performance by analyzing CT number standard deviations and variations. The modification resulted in improved reliability and consistency in CT number standardization. Additionally, for a detailed analysis, we segmented the dataset based on CT dose index (CTDI), X-ray tube potential, and reconstruction algorithms to examine the impact of different scanning protocols on standardization performance.
17
Saravanakumar, A., K. Vaideki, K. N. Govindarajan, and S. Jayakumar. "Development of indigenous cost effective pediatric head and body computed tomography dose index (CTDI) phantom for pediatric CT dose measurement." Physica Medica 30 (2014): e51. http://dx.doi.org/10.1016/j.ejmp.2014.07.156.
Full text
18
Gorges, Verena, and Waldemar Zylka. "Reducing dose of Cone-Beam CT used for patient positioning in radiooncology." Current Directions in Biomedical Engineering 7, no. 2 (2021): 227–30. http://dx.doi.org/10.1515/cdbme-2021-2058.
Full textAbstract:
Abstract Cone-Beam computed tomography (CBCT) has become the most important component of modern radiotherapy for positioning tumor patients directly before treatment. In this work we investigate alternations to standard acquisition protocol, called preset, for patients with a tumor in the thoracic region. The effects of the changed acquisition parameters on the image quality are evaluated using the Catphan Phantom and the image analysis software Smári. The weighted CT dose index (CTDIW) is determined in each case and the effects of the different acquisition protocols on the patient dose are classified accordingly. Additionally, the clinical suitability of alternative presets is tested by investigating correctness of image registration using the CIRS thorax phantom. The results show that a significant dose reduction can be achieved. It can be reduced by 51% for a full rotation by adjusting the gantry speed. A more patientspecific uptake protocol for patients with laterally located tumor was created which allows a dose reduction of 54%.
19
Kara, Ümit. "Fetal Dose in CT Scans During Pregnancy." Süleyman Demirel Üniversitesi Sağlık Bilimleri Dergisi 16, no. 1 (2025): 89–101. https://doi.org/10.22312/sdusbed.1568145.
Full textAbstract:
Objective: In situations where computed tomography (CT) scans are necessary for pregnant patients, such as in cases of trauma or other conditions that provide clinical benefit, accurately estimating the radiation dose to which the fetus is exposed is crucial. However, current methods are not sufficiently practical or feasible for routine clinical use. This study aims to assess and calculate the fetal dose and associated organ doses resulting from CT scans in pregnant patients using the Monte Carlo Simulation Method. Methods: Monte Carlo (MC) simulations and related calculations were conducted on pregnant patient phantoms for different gestational periods (8-15 weeks) using a 64-slice CT scanner (Discovery CT750 HD GE Healthcare) to estimate fetal doses. Organ dose calculations were also carried out. The MC code simulating dose distributions was validated with measurements from the CT Dose Index (CTDI) following AAPM protocols. Volumetric CTDI values from the MC simulations were normalized, enabling the development of a calculation algorithm for fetal dose assessments across different body regions and exposure settings. The algorithm, approved by the institutional review board, was validated through patient-specific MC simulations on CT data from pregnant patients (with gestational ages of 8-15 weeks) who had undergone CT scans. Results: Based on the data, it can be concluded that the fetus was exposed to low radiation doses, which do not present significant risk to fetal development. The doses observed in the study fell within acceptable clinical limits, indicating that fetal radiation exposure during CT scans can be managed safely with appropriate protocols. However, minimizing radiation exposure during pregnancy is essential. The use of low-dose protocols, as demonstrated in this study, is especially important for these patients. Moreover, the study’s findings highlight the importance of optimizing CT scan parameters and adopting radiation reduction strategies in routine clinical practice. Alternative imaging methods that utilize non-ionizing radiation, such as ultrasound or MRI, should also be considered when clinically appropriate. Conclusions: This study provides a clinically applicable approach to calculating fetal radiation doses during CT scans. The developed algorithm can help reduce fetal exposure and ensure patient safety. Future studies could expand on this research by validating the algorithm in larger patient cohorts and different gestational stages. The findings emphasize the need for radiology technologists to use the lowest possible dose protocols and explore non-ionizing imaging alternatives whenever feasible. .
20
Lubis, Lukmanda Evan, Windi Dliya Najmah, Yuni Muliyanti, et al. "Development, Construction, and Evaluation of an Alternative Dosimetry Phantom for Computed Tomography." Journal of Medical Physics 48, no. 4 (2023): 402–8. http://dx.doi.org/10.4103/jmp.jmp_92_23.
Full textAbstract:
This article aims to present the development, construction, and evaluation of an alternative computed tomography dose index (CTDI) phantom. Epoxy resin was mixed with an iodine-based contrast agent to produce radiological characteristics resembling polymethyl methacrylate (PMMA) as a standard CTDI phantom. As a preliminary study, testing was carried out using computed tomography images (80 and 120 kVp) on 12 variations of epoxy-iodine resin mixtures to obtain relative electron density (ρe ) values and effective atomic numbers (Zeff ) of the samples. The alternative CTDI phantoms were then constructed with a resin-iodine mixture using iodine concentrations that yield on closest ρe and Zeff values to those of PMMA. The evaluation was carried out by comparing dose measurement results at various energies between the alternative phantom and the International Electrotechnical Commission-standard CTDI phantom. At a concentration of 0.46%, the epoxy resin has ρe and Zeff with a deviation against PMMA of 0.12% and 1.58%, respectively, so that composition was chosen for the alternative CTDI phantom construction. The average dose discrepancy values were 5% and 1%, respectively, for the head and body phantoms in the tested tube voltages of 80 kVp, 100 kVp, 120 kVp, and 135 kVp. The Student’s t-test result between the alternative and the standard phantoms also showed P < 0.05, indicating the comparability of the alternative CTDI phantom with the standard CTDI phantom.
21
Maharjan, Surendra, Sudil Prajapati, and Om Biju Panta. "Measurement of radiation dose in multi-slice computed tomography." Bangabandhu Sheikh Mujib Medical University Journal 9, no. 4 (2016): 196. http://dx.doi.org/10.3329/bsmmuj.v9i4.30143.
Full textAbstract:
<p>The aim of this study was to measure the radiation doses for computed tomography (CT) examinations of the head, chest and abdomen in adult patients in Nepal in comparison to international standard. Dose length products (DLP) and effective doses for standard patient sizes were calculated from the reported volume CT dose index (CTDI<sub>Vol</sub>). Details were obtained from approximately 90 CT examinations carried out in 128 slice CT scan. Effective dose was calculated for each examination using CT dose indices, exposure related parameters and CTDI-to-effective dose conversion factors. The CTDI and DLP were below the established international reference dose levels for head and chest while for the abdomen and pelvis, the CTDl and DLP were above the established international reference dose levels. The mean effective doses in this study for the head, chest, and abdomen were 1.7, 5.4 and 17.7 mGy respectively. In conclusion, for the routine head and chest protocol, CTDI, DLP and ED were found to be significantly lower compared to the recommendation of European Commission. However, abdomen CT scans showed higher dose values because of multiple phase scans and longer scan lengths.</p>
22
Mekonin, Tadelech S., and Tilahun T. Deressu. "Computed Dosimeter Dose Index on a 16-Slice Computed Tomography Scanner." Dose-Response 20, no. 3 (2022): 155932582211192. http://dx.doi.org/10.1177/15593258221119299.
Full textAbstract:
A computed tomography dose index can be used to quantify the radiation dose received during a CT scan and it is an indicator of the radiation dose to the polymetaylenmetaAcrylate (PMMA) standardized phantom. The objective of this study was 2-fold. The first was to measure the computed tomography (CT) radiation dose for the head and body polymetaylelenmetaAcrylate (PMMA) phantoms and to determine the accuracy of the CT radiation dose parameter displayed on the CT scanner console; these were measured in this investigation and compared with the dose displayed on the CT scanner console. The dose was calculated using the formalism described in the American Association of Physics in Medicine (AAPM) Report 96. The second was to compare the dosimetric results of the head and body polymetaylelenmetaAcrylate (PMMA) phantoms with dose reference levels published in international journals, as well as to measure the central cumulative dose (DL′ (0)), as recommended by the American Association of Physics in Medicine (AAPM) report 111. This is a new, cutting-edge methodology for estimating the CT radiation dosage provided by the abdomen, thorax, and head of a PMMA phantom. We used a Philips Big Bore CT scanner with 16 slices. A CT dosimeter head phantom with a diameter of 16 cm, a CT dosimeter body phantom with a diameter of 32 cm, a 100 mm pencil chamber (PC), and a 20 mm short chamber (SC) were employed. These were coupled to an electrometer and a dosimetric readout device. The measured volume computed tomography dose index (CTDIvol) values were in good agreement with the CT radiation dose displayed on the corresponding CT scanner console. The percentage disagreement was less than 10%, with a maximal difference of 1.7% and 5.5% for the body and head phantom, respectively. The central cumulative dose (DL (0)) measurements (for L′ = 100 mm) also matched nominal or the corresponding computed tomography dose index (CT) scanner console volume computed tomography dose index (CTDIvol) values. In this case, the agreement is always below 3% for abdomen scans and 1.0% for head examinations. This result implies that the radiation dose supplied by the 16-slice computed tomography (CT) system was in good agreement with the international dose reference level and we observed something different.
23
Arfat, Mohd, Afifa Haq, Tarana Beg, and Ghufran Jaleel. "Optimization of CT radiation dose: Insight into DLP and CTDI." Future Health 2 (September 26, 2024): 148–52. http://dx.doi.org/10.25259/fh_45_2024.
Full textAbstract:
The computed tomography dose index (CTDI) and dose–length product (DLP) are critical for monitoring and optimizing radiation doses. CTDI estimates the dose per slice, whereas DLP calculates the total dose across the scanned area. These measures enhance consistency in dose assessments, make comparisons easier, and assist in keeping doses within regulatory limits. This article explores the functions of CTDI and DLP in CT imaging, focusing on their importance in dosage optimization and patient safety. Understanding and monitoring this information allows healthcare professionals to strike a compromise between high-quality imaging and reduced radiation exposure, assuring patient care and regulatory compliance.
24
Albngali, Ahmad. "New Advances in CT Dosimetry: The Planar Average Equilibrium Dose." Saudi Journal of Radiology 1, RSSA (2023): 74–80. http://dx.doi.org/10.55038/sjr.v1irssa.117.
Full textAbstract:
Background: The basis for the current output dose measurement in CT is the computer tomography dose index (CTDI). Modern CT scanners with helical scanning modes, dosage modulation, array detectors, multiple slice planes, or cone-beam irradiation geometries are incompatible with the conventional methods for measuring CT dosimetric performance. The AAPM TG 111 study acknowledged the shortcomings of the CTDI methods and suggested a new method that uses a short conventional ion chamber instead of a pencil chamber and better characterizes the dose profile from contemporary CT scanners.
 
 Materials and Methods: Three different anatomical regions (head, chest, and abdomen) of clinical scan sequences were used to build and characterize an in-house phantom design. The equilibrium dosage in our phantom was estimated to determine whether the attenuation of the beam was the same as that of the CTDI phantom. The obtained measurements were compared to those of the CTDI dose estimates made using a conventional pencil chamber.
 
 Results: The proposed method allowed the assessment of the equilibrium dosage as well as the accumulation dose for any clinical scan length. By contrast, the CTDI approach can underestimate the dose by 25% to 35% according to our revised methodology
 
 Conclusion: The CTDI measurements could no longer be sufficient, and the informed CTDI tends to underestimate the dose provided.
25
Saputri, Lutfiana Desy, Budi Santoso, Agung Nugroho Oktavianto, and Febria Anita. "Analisis Dosis Serap CT Scan Thorax Dengan Computed Tomography Dose Index Dan Thermoluminescence Dosimeter." Jurnal Ilmiah Giga 20, no. 1 (2019): 10. http://dx.doi.org/10.47313/jig.v20i1.546.
Full textAbstract:
Pemeriksaan CT scan thorax banyak digunakan dirumah sakit untuk mengetahui penyakit atau kelainan yang terdapat pada mediastinum atau paru-paru. Selama scanning, pasien mendapatkan radiasi pada pesawat CT scan. Perkiraan dosis yang diterima pasien sudah ada pada layar monitor yaitu nilai CTDI, namun untuk mengetahui dosis sebenarnya yang diterima pasien maka perlu pengukuran langsung menggunakan TLD yang ditempelkan pada tubuh pasien selama proses scanning. Tujuan penelitian ini adalah untuk mengetahui besarnya dosis yang diterima pasien selama CT scan thorax, membandingkan besar dosis yang diterima pasien dengan menggunakan TLD dan nilai CTDI yang tertera pada layar monitor selama CT scan thorax, mengetahui hasil ukur dosis masih dalam batas panduan monitor selama CT scan yang ditetapkan atau tidak, mengetahui hubungan antara hasil ukur dosis dengan DLP pada pasien selama CT Scan thorax. Penelitian diawali dengan pengukuran konsistensi keluaran tegangan tabung sinar-X (kVp Output). Lalu dilakukan pengukuran dosis radiasi pada area thorax dengan menggunakan chips TLD-100 yang ditempelkan pada permukaan area thorax terhadap 9 pasien yang berbeda-beda. Chips TLD-100 ditempelkan pada 3 titik yaitu caput humerus kanan, caput humerus kiri, dan sternum. Hasil penelitian menunjukkan bahwa (1) besarnya dosis radiasi yang diterima pasien selama CT scan thorax sebesar 16,19 mGy sampai dengan 27,66 mGy. (2) prosentasi perbedaan hasil ukur terhadap CTDI vol sebesar 0,06%-70,74%, adanya perbedaan rerata dosis pada tiga titik pengukuran yaitu caput humerus kanan sebesar 17,6 mGy, caput humerus kiri sebesar 16,52 mGy, dan sternum sebesar 25,4 mGy. (3) penerimaan dosis rata-rata pasien pada CT Scan thorax masih dalam batas panduan dosis CT scan yang ditetapkan oleh European Commission, yaitu sebesar 30 mGyuntuk CT thorax rutin, namun nilai DLP yang didapatkan berada diatas panduan dosis yang ditetapkan. (4) hasil ukur dosis berbanding lurus dengan DLP ( dose length ProduCT) yang diterima pasien.
26
Holroyd, John R., and Sue Edyvean. "Doses from cervical spine computed tomography (CT) examinations in the UK." British Journal of Radiology 91, no. 1085 (2018): 20170834. http://dx.doi.org/10.1259/bjr.20170834.
Full textAbstract:
Objective: To review doses to patients undergoing cervical spine CT examinations in the UK. Methods: A data collection form was developed and distributed to medical physicists and radiographers via e-mail distribution lists. The form requested details of CT scanners, exposure protocols and patient dose index information. Results: Data were received for 73 scanners. It was seen that 97% of scanners used automatic exposure control, and 60% of scanners used an iterative reconstruction technique for cervical spine examinations. The majority of scans were taken at 120 kV. The average patient dose indicators in terms of CT dose index (CTDIvol) ranged from 3.5 to 39.7 mGy (mean value 16.7 mGy), and for the DLP, ranged from 87 to 1030 mGy cm (mean value 379 mGy cm) as quoted for the standard 32 cm phantom. Conclusion: The rounded third quartile value of the mean dose distributions from this study were a CT dose index (CTDIvol) of 20 mGy and a dose–length product of 440 mGy cm as quoted for a 32 cm body phantom. These are significantly higher than those in the 2011 Public Health England CT dose survey when adjusted for phantom size. It is suggested that the existing national diagnostic reference levels for cervical spine CT should be amended, both with the new values and also to quote according to the 32 cm phantom. Advances in knowledge: Proposed new national diagnostic reference levels are presented for cervical spine CT examinations.
27
Tran, Khanh Ai, Thong Minh Cao, Phuong Nguyen Dang, Loan Thi Hong Truong, and Nhon Van Mai. "Calculation of the shielding safety of Computed Tomography scanner room by using MCNP5 code." Science and Technology Development Journal - Natural Sciences 1, T4 (2017): 63–70. http://dx.doi.org/10.32508/stdjns.v1it4.476.
Full textAbstract:
Shielding design of Computed Tomography scanner room is a vital work to ensure radiation safety for medical physicists and public. In this paper, we measured CTDI (CT Dose Index) and determined the normalization factor between Monte Carlo simulation and experiment values of absorbed dose. Then, the absorbed dose distribution inside and outside the CT scanner room were surveyed for the variation of the room size. In addition, the influence of photons scattered from the shielding material to patients while shrinking the sizes of the room is also studied in this work.
28
Anam, Choirul, Riska Amilia, Ariij Naufal, Yanurita Dwihapsari, and Geoff Dougherty. "A system to investigate and adjust profile pattern of computed tomography dose index along the longitudinal-axis." International Journal of Public Health Science (IJPHS) 12, no. 4 (2023): 1656. http://dx.doi.org/10.11591/ijphs.v12i4.23291.
Full textAbstract:
The purpose of this study to develop software to extract and investigate the rofiles of the tube current and volume computed tomography dose index (CTDI<sub>vol</sub>) along the longitudinal axis (z-axis). The tube current and CTDI<sub>vol</sub> were extracted from the Digital Imaging and Communications in Medicine (DICOM) header of every image along the longitudinal axis. We evaluated the profiles of the tube current and CTDI<sub>vol</sub> from eight computed tomography (CT) scanners. If the CTDI<sub>vol</sub> did not fluctuate along the fluctuation of the tube currents, then the system will adjust the CTDI<sub>vol</sub> with tube currents. It is found that TCM is not always activated. If TCM is activated, the profiles of TCM vary from one scanner to another. The Siemens and Philip scanners have adjusted the CTDI<sub>vol</sub> profile with tube current, but the Toshiba scanner has not. By developed software, CTDI<sub>vol</sub> profile of the Toshiba can be easily adjusted. In conclusion, software to investigate the profile pattern of CTDI<sub>vol</sub> along the longitudinal axis has been successfully developed. The software is easy to use and works quickly. From this study, medical staff must be careful when using the CTDI<sub>vol</sub> along longitudinal axis contained in each DICOM header.
29
Saidu, Naim, Ahmed R. Usman, Sanusi K. Rabiu, and Usman Ibrahim. "Assessment of radiation dose for pediatric patients under computed tomography examination at Federal Teaching Hospital, Katsina." Equity Journal of Science and Technology 11, no. 1 (2025): 86–90. https://doi.org/10.4314/equijost.v11i1.14.
Full textAbstract:
The current upsurge in computed tomography (CT) examinations has resulted in concurrent increase in medical exposure to ionizing radiation worldwide. In view of this, research efforts in various x-ray producing machines help to quantify dose incurred by patients and examine the associated cancer risks from the medical radiations, especially in children. Thus, the current work evaluates radiation dose received by pediatric patients who underwent CT examinations at Federal Teaching Hospital, Katsina. A total number of twenty-five (25) pediatric patients within the age range of 0-15 years were considered for the study, with male patients having the highest number (44 %) of patients than female (44 %). The results obtained were presented in terms of volumetric computed tomography dose index (CTDI-vol) and dose length product (DLP) for Brain, Chest and abdomen. The average values of the CTDI-vol and DLP recorded were 19.31mGy and 458.22mGY.cm respectively. While the highest tube potential of 120 kV was used, the tube current was kept within the range of 40-150mA. The lead to noticeable variation in CTDI-vol, and DLP values across different anatomical regions and age groups. The chest and abdomen CT examinations showed a relatively lower radiation doses compared to head (brain) examinations. Possibly due to their deeper anatomical region. By quantifying the CTDI-vol and DLP in Ct examinations, this study therefore provides useful data for relevant authorities for management of radiations to patients as well as increased awareness of radiation exposure among public. The present work would also help relevant professionals and government to develop new strategies for optimizing radiation dose and adopting individualized imaging protocols for pediatric patients to ensure delivery of relatively safe and effective medical care for the immediate population.
30
Guillochon, Nicolas, Mamoutou Balde, Christian Popotte, et al. "Validation of a New Scintillating Fiber Dosimeter for Radiation Dose Quality Control in Computed Tomography." Sensors 23, no. 5 (2023): 2614. http://dx.doi.org/10.3390/s23052614.
Full textAbstract:
(1) Background: The IVIscan is a commercially available scintillating fiber detector designed for quality assurance and in vivo dosimetry in computed tomography (CT). In this work, we investigated the performance of the IVIscan scintillator and associated method in a wide range of beam width from three CT manufacturers and compared it to a CT chamber designed for Computed Tomography Dose Index (CTDI) measurements. (2) Methods: We measured weighted CTDI (CTDIw) with each detector in accordance with the requirements of regulatory tests and international recommendations for the minimum, maximum and the most used beam width in clinic and investigated the accuracy of the IVIscan system based on the assessment of the CTDIw deviation from the CT chamber. We also investigated the IVIscan accuracy for the whole range of the CT scans kV. (3) Results: We found excellent agreement between the IVIscan scintillator and the CT chamber for the whole range of beam widths and kV, especially for wide beams used on recent technology of CT scans. (4) Conclusions: These findings highlight that the IVIscan scintillator is a relevant detector for CT radiation dose assessments, and the method associated with calculating the CTDIw saves a significant amount of time and effort when performing tests, especially with regard to new CT technologies.
31
Hanu, Christine, Burk W. Loeliger, Irina V. Panyutin, et al. "Effect of Ionizing Radiation from Computed Tomography on Differentiation of Human Embryonic Stem Cells into Neural Precursors." International Journal of Molecular Sciences 20, no. 16 (2019): 3900. http://dx.doi.org/10.3390/ijms20163900.
Full textAbstract:
We studied the effect of radiation from computed tomography (CT) scans on differentiation of human embryonic stem cells (hESCs) into neuronal lineage. hESCs were divided into three radiation exposure groups: 0-dose, low-dose, or high-dose exposure. Low dose was accomplished with a single 15 mGy CT dose index (CTDI) CT scan that approximated the dose for abdominal/pelvic CT examinations in adults while the high dose was achieved with several consecutive CT scans yielding a cumulative dose of 500 mGy CTDI. The neural induction was characterized by immunocytochemistry. Quantitative polymerase chain reaction (qPCR) and Western blots were used to measure expression of the neuronal markers PAX6 and NES and pluripotency marker OCT4. We did not find any visible morphological differences between neural precursors from irradiated and non-irradiated cells. However, quantitative analyses of neuronal markers showed that PAX6 expression was reduced following exposure to the high dose compared to 0-dose controls, while no such decrease in PAX6 expression was observed following exposure to the low dose. Similarly, a statistically significant reduction in expression of NES was observed following high-dose exposure, while after low-dose exposure, a modest but statistically significant reduction in NES expression was only observed on Day 8 of differentiation. Further studies are warranted to elucidate how lower or delayed expression of PAX6 and NES can impact human fetal brain development.
32
Shim, Jina, Yong Eun Chung, Hyun-Woo Jeong, and Youngjin Lee. "Feasibility Study of Dose Modulation for Reducing Radiation Dose with Arms-Down Patient Position in Abdominal Computed Tomography." Diagnostics 12, no. 2 (2022): 323. http://dx.doi.org/10.3390/diagnostics12020323.
Full textAbstract:
This study was carried out to demonstrate whether the radiation dose for patients in arms-down position can be reduced without affecting the diagnosis on abdominal computed tomography (CT). The patients were divided into two groups: group A, which included patients with arms-down position using dose modulation on, and group B, which included patients with arms-down position using dose modulation turned off. Quantitative evaluation was compared using Hounsfield units, standard deviation, and signal-to-noise ratio of the four regions. The qualitative evaluation was assessed for overall image quality, subjective image noise, and beam hardening artifacts. Dose evaluation for CT dose index (CTDI) and dose length product (DLP) was compared by comparing the CT images with dose modulation turned on and off. In the quantitative and qualitative evaluation, there was no statistically significant difference between groups A and B (p > 0.05). In the dose evaluation, the CT images with dose modulation turned off had significantly lower CTDI and DLP than the CT images with dose modulation turned on (p < 0.05). Our results suggest that, for the GE Revolution EVO CT scanner, turning off dose modulation and increasing the tube voltage can reduce the radiation dose for patients with the arms-down position without affecting the diagnosis. This study did not consider the change of tube potential according to the use of dose modulation, and we plan to conduct additional research in the future.
33
Sukanta, I. Gede Eka, Made Sayang Pratista, I. Wayan Angga Wirajaya, and Anak Agung Aris Diarthama. "ANALISA PERUBAHAN KV TERHADAP KUALITAS CITRA DAN CTDI." JRI (Jurnal Radiografer Indonesia) 5, no. 1 (2022): 36–41. http://dx.doi.org/10.55451/jri.v5i1.106.
Full textAbstract:
Background : Improved CT Scan image quality with tube variation once reported that higher tube voltage results in better image quality. But the study was conducted to evaluate the tube voltage of 80 kv to lower the dose so that the current of the tube is not increased. Some researchers recommend scanning with low tube voltage and properly adjusted tube current to reduce radiation doses on brain CT scans. However, so far there has never been an evaluation of kV values on image quality and CTDI in the head MSCT and at Sanjawani Hospital to analyze Kv changes to image quality and CTDI multislice computed tomography on phantoms.
 Methods:The study was conducted on the Phantom using the parameters of the HEAD CT scan examination. This research method is quantitative research with an experimental approach. The study was conducted on the Phantom using the parameters of the HEAD CT scan examination.
 Results: This study was conducted by collecting kV variation data of 70, 80, 100, 120, and 140 scanned 3 times.
 Conclusion : The results obtained the output of spss friedman test spatial resolution, contrast resolution, nooise and artifact, the highest rank is at kV tube voltage 120. Ctdi value obtained with kV variari, is in accordance with bapeten / IDRL 2021 recommendations.
34
Sukanta, I. Gede Eka, Made Sayang Pratista, I. Wayan Angga Wirajaya, and Anak Agung Aris Diarthama. "ANALISA PERUBAHAN KV TERHADAP KUALITAS CITRA DAN CTDI." JRI (Jurnal Radiografer Indonesia) 5, no. 1 (2022): 36–41. http://dx.doi.org/10.55451/jri.v5i1.106.
Full textAbstract:
Background : Improved CT Scan image quality with tube variation once reported that higher tube voltage results in better image quality. But the study was conducted to evaluate the tube voltage of 80 kv to lower the dose so that the current of the tube is not increased. Some researchers recommend scanning with low tube voltage and properly adjusted tube current to reduce radiation doses on brain CT scans. However, so far there has never been an evaluation of kV values on image quality and CTDI in the head MSCT and at Sanjawani Hospital to analyze Kv changes to image quality and CTDI multislice computed tomography on phantoms.
 Methods:The study was conducted on the Phantom using the parameters of the HEAD CT scan examination. This research method is quantitative research with an experimental approach. The study was conducted on the Phantom using the parameters of the HEAD CT scan examination.
 Results: This study was conducted by collecting kV variation data of 70, 80, 100, 120, and 140 scanned 3 times.
 Conclusion : The results obtained the output of spss friedman test spatial resolution, contrast resolution, nooise and artifact, the highest rank is at kV tube voltage 120. Ctdi value obtained with kV variari, is in accordance with bapeten / IDRL 2021 recommendations.
35
Shah, Pooja, Amish Sharma, Jayanti Gyawali, Sharma Paudel, Shanta Lall Shrestha, and Surendra Maharjan. "Dose optimization in computed tomography of brain using CARE kV and CARE Dose 4D." Radiography Open 4, no. 1 (2018): 9. http://dx.doi.org/10.7577/radopen.3110.
Full textAbstract:
Background: Computed Tomography (CT) scan of brain is the most widely used CT examination. Latest CT scanners have the potential to deliver very low radiation dose by utilizing tube potential and tube current modulation techniques. We aim to determine the application of CARE kV (tube potential modulation) and CARE Dose4D (tube current modulation) in CT scan of brain. Both CARE kV and CARE Dose4D are well-established innovative technology of Siemens Medical Solutions.
 Methodology: A prospective hospital-based study was conducted during four months at Tribhuvan University Teaching Hospital (TUTH). The data were collected on a Siemens Somatom Definition Edge 128 slices CT scanner. Non-random purposive sampling technique was employed. Ethical approval and consent to participate were taken for every participant. Non-contrast (NC) CT images were acquired without using CARE kV and CARE Dose4D, whereas during contrast-enhanced (CE) investigation, both were turned on keeping other scanning parameters constant for each individual.
 Results: A total of 72 patients, 42 males and 28 females - mean age 41y (range 16-87y) participated in this study. The Body Mass Index (BMI) was 22.0, range 20.1-25.0. The mean value of Computed Tomography Dose Index (CTDI), Dose Length Product (DLP) and Effective Dose (ED) before and after switching on both CARE kV and CARE Dose4D were 58.19±0.35 and 39.67±3.59 milli-Gray (mGy), 946.67 and 652.58 mGy-cm, and 1.98 and 1.36 milli-Sievert (mSv) respectively.
 Conclusion: CARE kV and CARE Dose4D can reduce radiation dose in CT scan of brain without loss of image quality.
36
Midgley, Stewart, Nanette Schleich, Alex Merchant, and Andrew Stevenson. "CT dosimetry at the Australian Synchrotron for 25–100 keV photons and 35–160 mm-diameter biological specimens." Journal of Synchrotron Radiation 26, no. 2 (2019): 517–27. http://dx.doi.org/10.1107/s1600577518018015.
Full textAbstract:
The dose length product (DLP) method for medical computed tomography (CT) dosimetry is applied on the Australian Synchrotron Imaging and Medical Beamline (IMBL). Beam quality is assessed from copper transmission measurements using image receptors, finding near 100% (20 keV), 3.3% (25 keV) and 0.5% (30–40 keV) relative contributions from third-harmonic radiation. The flat-panel-array medical image receptor is found to have a non-linear dose response curve. The amount of radiation delivered during an axial CT scan is measured as the dose in air alone, and inside cylindrical PMMA phantoms with diameters 35–160 mm for mono-energetic radiation 25–100 keV. The radiation output rate for the IMBL is comparable with that used for medical CT. Results are presented as the ratios of CT dose indices (CTDI) inside phantoms to in air with no phantom. Ratios are compared for the IMBL against medical CT where bow-tie filters shape the beam profile to reduce the absorbed dose to surface organs. CTDI ratios scale measurements in air to estimate the volumetric CTDI representing the average dose per unit length, and the dose length product representing the absorbed dose to the scanned volume. Medical CT dose calculators use the DLP, beam quality, axial collimation and helical pitch to estimate organ doses and the effective dose. The effective dose per unit DLP for medical CT is presented as a function of body region, beam energy and sample sizes from neonate to adult.
37
Alrowaili, Ziyad Awadh, and M. Ashari. "Evaluation of Radiation Doses from Computed Tomography Conducted in Al Jouf Region (Saudi Arabia)." Journal of Medical Imaging and Health Informatics 11, no. 8 (2021): 2194–200. http://dx.doi.org/10.1166/jmihi.2021.3668.
Full textAbstract:
A safe radiation dose from computed tomography (CT) is normally specified through the Computed Tomography Dose Index (CTDI) as an “effective dose.” Radiation exposure from CT is relatively high in comparison with other radiological tests. In this paper, we evaluate doses used on adult patients during typical CT scans, in Al Jouf, the northern region of Saudi Arabia. Scanning processes were taken place in different parts of the body; including the pelvis, head, abdomen, and chest. The dose indices were calculated using the CT-expo v2.5 computer software. A comparison of the results with similar investigations, regionally and globally, was made. Other comparisons between displayed and calculated dose indices were also performed. The main values of CT volume are the dose index (CTDIvol) and dose-length product (DLP). The effectiveness results for head CTs were 45.0 mGy, 488 mGy.cm, and 5.2 mSv; while for pelvic CTs they were 16.4 mGy, 391 mGy.cm, and 4.0 mSv; whereas for abdominal CTs they were 22.2 mGy, 613 mGy.cm, and 6.5 mSv; finally they were 17.5 mGy, 380 mGy.cm, and 3.9 mSv for chest CTs. It is confirmed that the values obtained are within the internationally accepted values, except for the values of the head examination, in which the effective dose value of 5.2 mSv was higher than the recommended value. This work gives an overview of the doses received by adult patients during regular CT examination. It is the first regional CT dose survey and provides a baseline for improvement and quality control in the region of Al Jouf.
38
Alhaji Barde, Mustapha, Noor Diyana Osman, Mohd Amir Syahmi Mat Razali, Hafizah Mohd Naharuddin, Fatanah Mohamad Suhaimi, and Nor Ashidi Mat Isa. "Truncation Effects on Effective Diameter Measurement for Size-specific Dose Estimation in Computed Tomography (CT) Imaging." Asian Journal of Medicine and Biomedicine 6, S1 (2022): 23–24. http://dx.doi.org/10.37231/ajmb.2022.6.s1.511.
Full textAbstract:
The determination of size specific dose estimation (SSDE) has been proposed for accurate CT dose assessment. The SSDE introduction has prompted numerous manufacturers and researchers to develop various methodologies that have progressed from manual to automated methods in SSDE determination. Few studies reported on truncation effects with respect to specific size and SSDE determination and CT manufacturers are yet to incorporate truncation correction in their system [1,2].
 This study aimed to evaluate the effects of truncation artifacts on the measurement of effective diameter (Deff) and SSDE in CT imaging. A phantom study was performed using CTDI phantom of different diameters, 22 and 32 cm with Siemens SOMATOM Definition AS+ CT scanner. Phantom images of different truncation percentage (TP) of 5%, 10%, 15%, and 20% were simulated and acquired. The Deff and SSDE were determined based on the displayed CTDIvol, and the AAPM correction factor table was used to calculate the SSDE accurately [3]. The percentage error for each TP in comparison with non-truncated image (TP 0%) was computed.
 Results showed the percentage error (PE) for both Deff and SSDE increased as the TP increased. The PE was determined by comparing the Deff and SSDE of each TP with non-truncated (TP 0%) image. Table 1 shows the values of PE of truncated images of different TP (5%, 10%, 15%, and 20%) for both Deff and SSDE in phantom sizes of 22 and 32 cm. However, it can be observed that PE values for SSDE of 5% and 10% truncation were similar for both phantom sizes. This is because the correction factors for 5% and 10% were similar and had resulted in similar calculated SSDE. The highest recorded PE was observed in 20% truncation that determined the largest difference in Deff and SSDE with non-truncated image.
 This study demonstrates that there is a linear relationship between truncation percentage with measured Deff and SSDE computation. It can be concluded that the percentage error in Deff measurement and calculated SSDE will increase as TP increased. Therefore, the effects of truncation artefacts should be carefully considered in SSDE calculation for accurate estimation especially in development of automated calculation.
39
Samuel Ibe, Blessing, Akpama Egwu Egong, Akwa Egom Erim, et al. "Acquisition Of Size-Specific Dose Estimates For Abdominal Computed Tomography Examination In Nigeria: A Preliminary Study Using A Water Equivalent Diameter." Global Journal of Pure and Applied Sciences 31, no. 1 (2025): 113–21. https://doi.org/10.4314/gjpas.v31i1.10.
Full textAbstract:
Background Size-specific dose estimates is an important metric for personalizing dose measurements during abdominal computed tomography (CT) examination. This study aimed to establish patient size-specific dose data as a guide for dose monitoring of abdominal computed tomography examinations among Nigerians. Methods Abdominal CT images of adult subjects obtained from two CT scanners - a light speed VCT –ZTe; (GE Healthcare) 16 – Slice and a Brivo CT 385 series; (GC Healthcare) 16-slice scanners were used in the study. The estimated computed tomography dose index volume (CTDIvol) and dose length product (DLP) were extracted from the CT dose report on the patients’ electronic Image folders. The effective size of the abdomen was obtained by using electronic caliper on the scanner console to measure the anterior-posterior and lateral dimensions at the level of the widest diameter on the image. With Table1A from the AAPM report 220, conversion factors were determined for a total of 264 abdominal CT images. The corresponding conversion factor was multiplied by the CTDIvol to obtain the size specific dose estimates (SSDE). The relationships between effective diameter (ED), CTDIVOL and age on SSDE were analyzed using minitab statistical software version 17. Results The mean CTDlvol was 6.94+ 1.63mGy, while SSDE was 9.76 + 2.56mGy. The SSDE decreased significantly with effective diameter, and increased significantly with the CTDI vol. The effective diameter measured between 8.72.90 and 37.70cm. Conclusion The study concludes that the CTDvol and patient’s abdominal size are determinant factors in the development of a size-specific radiation protection protocol and optimization of patient dose during abdominal CT examinations based on scanner output.
40
Zamani, Hamed, Hamidreza Masjedi, Reza Omidi, and Mohammad Hosein Zare. "ESTABLISHMENT OF LOCAL DIAGNOSTIC REFERENCE LEVELS FOR COMMON PROCEDURES OF COMPUTED TOMOGRAPHY IN YAZD PROVINCE." Radiation Protection Dosimetry 188, no. 2 (2019): 222–31. http://dx.doi.org/10.1093/rpd/ncz279.
Full textAbstract:
Abstract Objective: The aim of this study was to propose first established diagnostic reference levels (DRLs) in computed tomography (CT) for adults, based on volume-averaged CTDI and dose length product (DLP) metrics in Yazd Province. Materials and Methods: Six multislice CT scanners located at diverse areas of Yazd Province and seven common procedures were selected for the present study. For each procedure, at least twenty patients 18 years and older were sampled at each institution. For each patient, dose report data and scan parameters as well as patient’s information were abstracted from picture archiving and communication system. Results: Proposed DRLs in terms of computed tomography dose index (mGy) and DLP (mGy.cm) were as follows: brain (42, 527), sinus (25, 220), neck (14, 264), abdomen-pelvis (11, 295), routine chest (8, 247), CT pulmonary angiogram (32, 261) and chest HRCT (11, 455), respectively, slightly lower compared to other investigations. Conclusion: The proposed DRLs in this study should be considered as the local DRLs for the seven most common adult CT examinations in Yazd province so as to optimize the patient dose while maintaining acceptable image quality for the clinical task.
41
Ngaile, Justin E., Peter K. Msaki, Evarist M. Kahuluda, Furaha M. Chuma, Jerome M. Mwimanzi, and Ahmed M. Jusabani. "Effect of Lowering Tube Potential and Increase Iodine Concentration of Contrast Medium on Radiation Dose and Image Quality in Computed Tomography Pulmonary Angiography Procedure: A Phantom Study." Tanzania Journal of Science 47, no. 3 (2021): 1211–24. http://dx.doi.org/10.4314/tjs.v47i3.29.
Full textAbstract:
The aim of the study was to examine the effect of lowering tube potential and increase iodine concentration on image quality and radiation dose in computed tomography pulmonary angiography procedure. The pulmonary arteries were simulated by three syringes. The syringes were filled with 1:10 diluted solutions of 300 mg, 350 mg and 370 mg of iodine per millilitre concentration in three water-filled phantoms simulating thin, intermediate and thick patients. The phantoms were scanned at 80 kVp, 110 kVp and 130 kVp and 0.6 second rotation time using a 16 slice computed tomography (CT) scanner. The tube current was either fixed at 80, 100, 200, 250 and 300 mA or automatically adjusted with quality reference tube current-time product (mAsQR). In comparison with 130 kVp, images acquired at 80 kVp and 110 kVp, respectively, showed 76.2% to 99% and 19% to 26% enhancement in CT attenuation of iodinated contrast material. A volume CT dose index (CTDIvol) reduction by 35.3% was attained in small phantom with the use of 80 kVp, while in the medium phantom, a CTDIvol reduction by 29.9% was attained with the use of 110 kVp instead of 130 kVp. In light of the above, lowering tube potential and increase iodinated CM could substantially reduce the dose to small-sized adults and children.
 Keywords: Angiography; Computed tomography; Low tube potential; Iodinated contrast medium; Radiation dose
42
Chu, Philip W., Sophronia Yu, Yifei Wang, et al. "Reference phantom selection in pediatric computed tomography using data from a large, multicenter registry." Pediatric Radiology 52, no. 3 (2021): 445–52. http://dx.doi.org/10.1007/s00247-021-05227-0.
Full textAbstract:
Abstract Background Radiation dose metrics vary by the calibration reference phantom used to report doses. By convention, 16-cm diameter cylindrical polymethyl-methacyrlate phantoms are used for head imaging and 32-cm diameter phantoms are used for body imaging in adults. Actual usage patterns in children remain under-documented. Objective This study uses the University of California San Francisco International CT Dose Registry to describe phantom selection in children by patient age, body region and scanner manufacturer, and the consequent impact on radiation doses. Materials and methods For 106,837 pediatric computed tomography (CT) exams collected between Jan. 1, 2015, and Nov. 2, 2020, in children up to 17 years of age from 118 hospitals and imaging facilities, we describe reference phantom use patterns by body region, age and manufacturer, and median and 75th-percentile dose–length product (DLP) and volume CT dose index (CTDIvol) doses when using 16-cm vs. 32-cm phantoms. Results There was relatively consistent phantom selection by body region. Overall, 98.0% of brain and skull examinations referenced 16-cm phantoms, and 95.7% of chest, 94.4% of abdomen and 100% of cervical-spine examinations referenced 32-cm phantoms. Only GE deviated from this practice, reporting chest and abdomen scans using 16-cm phantoms with some frequency in children up to 10 years of age. DLP and CTDIvol values from 16-cm phantom-referenced scans were 2–3 times higher than 32-cm phantom-referenced scans. Conclusion Reference phantom selection is highly consistent, with a small but significant number of abdomen and chest scans (~5%) using 16-cm phantoms in younger children, which produces DLP values approximately twice as high as exams referenced to 32-cm phantoms
43
Sarma, Arnabjyoti Deva, Jibon Sharma, and Mrinal Kanti Singha. "A Review on Diagnostic Reference Levels for Adult Patients Undergoing Chest (Coronary Angiography) Computed Tomography Scan in North-East India." Asian Pacific Journal of Health Sciences 9, no. 3 (2022): 55–58. http://dx.doi.org/10.21276/apjhs.2022.9.3.12.
Full textAbstract:
In the radiological department, the computed tomography (CT) scan process has become a greater radiation dosage that contributes to all medical X-ray treatments. Many studies throughout the world have found that CT accounts for just 5% of all operations conducted yet accounts for 34% of yearly radiation exposures in all medical X-ray treatments. Similarly, other studies have found that CT accounts for 17% of all operations conducted worldwide but accounts for 49% of total yearly doses in all medical X-ray treatments. Because diagnostic reference levels (DRLs) are one of the ways of optimizing a dose in a CT procedure, the goal of this review is to provide a DRLs for adults who undergo chest and abdomen CT scan examinations in northern India, based on research for this region and comparing with international values to see if better optimization protocol is being practiced. DRLs for the chest are 18.35mGy for CT dose index volume (CTDIvol) and 765 mGy.cm for dose length product (DLP), according to this review, while DRLs for the abdomen are 18.25 mGy and 1870.75 mGy.cm for CTDI (vol) and DLP, respectively. As a result, all of the DRLs examined had greater values than the international values compared, with the exception of CTDI (vol) of International Commission on Radiological Protection 2007 publications. CT technology is in desperate need of an update. In the northern region, optimizing methods, including exposure and technical parameter selection, should reduce dose fluctuations.
44
Amalaraj, T., Duminda Satharasinghe, Aruna Pallewatte, and Jeyasingam Jeyasugiththan. "Establishment of national diagnostic reference levels for computed tomography procedures in Sri Lanka: first nationwide dose survey." Journal of Radiological Protection 42, no. 2 (2022): 021504. http://dx.doi.org/10.1088/1361-6498/ac40e8.
Full textAbstract:
Abstract The main purpose of this study was to establish for the first time national diagnostic reference levels (NDRLs) for common computed tomography (CT) procedures in Sri Lanka. Patient morphometric data, exposure parameters and dose data such as volume CT dose index (CTDI v o l ) and dose–length product (DLP) were collected from 5666 patients who underwent 22 types of procedure. The extreme dose values were filtered before analysis to ensure that the data come from standard size patients. The median of the dose distribution was calculated for each institution, and the third quartile value of the median distribution was considered as the NDRL. Based on the inclusion and exclusion criteria, data from 4592 patients and 17 procedure types were considered for establishment of a NDRL, covering 41% of the country’s CT machines. The proposed NDRLs based on CTDI v o l and DLP were: non-contrast-enhanced (NC) head, 82.2 mGy/1556 mGy cm; contrast-enhanced (CE) head, 82.2 mGy/1546 mGy cm; chest NC, 7.4 mGy/350 mGy cm; chest CE, 8.3 mGy/464 mGy cm; abdomen NC, 10.5 mGy/721 mGy cm; abdomen arterial (A) phase, 13.4 mGy/398 mGy cm; abdomen venous (V) phase, 10.8 mGy/460 mGy cm; abdomen delay (D) phase, 12.6 mGy/487 mGy cm; sinus NC, 30.2 mGy/452 mGy cm; lumbar spine NC, 24.1 mGy/1123 mGy cm; neck NC, 27.5 mGy/670 mGy cm; high-resolution CT of chest, 10.3 mGy/341 mGy cm; kidneys ureters and bladder NC, 19.4 mGy/929 mGy cm; chest to pelvis (CAP) NC, 10.8 mGy/801 mGy cm; CAP A, 10.4 mGy/384 mGy cm; CAP V, 10.5 mGy/534 mGy cm; CAP D, 16.8 mGy/652 mGy cm. Although the proposed NDRLs are comparable with those of other countries, the observed broad dose distributions between the CT machines within Sri Lanka indicate that dose optimisation strategies for the country should be implemented for most of the CT facilities.
45
Björkdahl, Peter, and Ulf Nyman. "Using 100- instead of 120-kVp computed tomography to diagnose pulmonary embolism almost halves the radiation dose with preserved diagnostic quality." Acta Radiologica 51, no. 3 (2010): 260–70. http://dx.doi.org/10.3109/02841850903505222.
Full textAbstract:
Background: Concern has been raised regarding the mounting collective radiation doses from computed tomography (CT), increasing the risk of radiation-induced cancers in exposed populations. Purpose: To compare radiation dose and image quality in a chest phantom and in patients for the diagnosis of pulmonary embolism (PE) at 100 and 120 peak kilovoltage (kVp) using 16-multichannel detector computed tomography (MDCT). Material and Methods: A 20-ml syringe containing 12 mg I/ml was scanned in a chest phantom at 100/120 kVp and 25 milliampere seconds (mAs). Consecutive patients underwent 100 kVp ( n = 50) and 120 kVp ( n = 50) 16-MDCT using a “quality reference” effective mAs of 100, 300 mg I/kg, and a 12-s injection duration. Attenuation (CT number), image noise (1 standard deviation), and contrast-to-noise ratio (CNR; fresh clot = 70 HU) of the contrast medium syringe and pulmonary arteries were evaluated on 3-mm-thick slices. Subjective image quality was assessed. Computed tomography dose index (CTDIvol) and dose–length product (DLP) were presented by the CT software, and effective dose was estimated. Results: Mean values in the chest phantom and patients changed as follows when X-ray tube potential decreased from 120 to 100 kVp: attenuation +23% and +40%, noise +38% and +48%, CNR −6% and 0%, and CTDIvol −38% and −40%, respectively. Mean DLP and effective dose in the patients decreased by 42% and 45%, respectively. Subjective image quality was excellent or adequate in 49/48 patients at 100/120 kVp. No patient with a negative CT had any thromboembolism diagnosed during 3-month follow-up. Conclusion: By reducing X-ray tube potential from 120 to 100 kVp, while keeping all other scanning parameters unchanged, the radiation dose to the patient may be almost halved without deterioration of diagnostic quality, which may be of particular benefit in young individuals.
46
Monnin, Pascal, Nicolas Sfameni, Achille Gianoli, and Sandrine Ding. "Optimal slice thickness for object detection with longitudinal partial volume effects in computed tomography." Journal of Applied Clinical Medical Physics 18, no. 1 (2016): 251–59. http://dx.doi.org/10.1002/acm2.12005.
Full textAbstract:
AbstractLongitudinal partial volume effects (z‐axial PVE), which occur when an object partly occupies a slice, degrade image resolution and contrast in computed tomography (CT). Z‐axial PVE is unavoidable for subslice objects and reduces their contrast according to their fraction contained within the slice. This effect can be countered using a smaller slice thickness, but at the cost of an increased image noise or radiation dose. The aim of this study is to offer a tool for optimizing the reconstruction parameters (slice thickness and slice spacing) in CT protocols in the case of partial volume effects. This optimization is based on the tradeoff between axial resolution and noise. For that purpose, we developed a simplified analytical model investigating the average statistical effect of z‐axial PVE on contrast and contrast‐to‐noise ratio (CNR). A Catphan 500 phantom was scanned with various pitches and CTDI and reconstructed with different slice thicknesses to assess the visibility of subslice targets that simulate low contrast anatomical features present in CT exams. The detectability score of human observers was used to rank the perceptual image quality against the CNR. Contrast and CNR reduction due to z‐axial PVE measured on experimental data were first compared to numerical calculations and then to the analytical model. Compared to numerical calculations, the simplified algebraic model slightly overestimated the contrast but the differences remained below 5%. It could determine the optimal reconstruction parameters that maximize the objects visibility for a given dose in the case of z‐axial PVE. An optimal slice thickness equal to three‐fourth of the object width was correctly proposed by the model for nonoverlapping slices. The tradeoff between detectability and dose is maximized for a slice spacing of half the slice thickness associated with a slice width equal to the characteristic object width.
47
Samia, A. Fathelrahman, T. Ahmed Albosairi, H. Khalid Najla, Esmaeal Ahmed Maha, and A. Al-bishr Hamad. "Study the variations in radiation doses in different multi-slice CT scan machines." GSC Advanced Research and Reviews 17, no. 2 (2023): 221–28. https://doi.org/10.5281/zenodo.10615227.
Full textAbstract:
<strong>Objectives:</strong> This study aimed to measure variations in dose output and patient’s effective dose across the different computed tomography scanners during standard CT examinations of head, chest and abdomen, so as to determine patient, and machine settings that contribute to variations in radiation dose to optimize patient effective dose. <strong>Methods:</strong> Retrospective, study performed in different hospitals, in Najran province (K.S.A) from October 2022 to June 2023. The study comprise 360 adults CT examinations. The mean values of CT dose index volume (CTDI<sub>vol</sub>) and dose length product (DLP) were measured. The patient effective dose (ED) were calculated for each protocol and compared among different CT scanners. <strong>Results: </strong>The mean values of CTDI<sub>vol</sub> , DLP, and ED, varied across the different CT scanners, Regarding abdomen CT, the CTDI<sub>vol</sub> mean values were (5.56 mGy to 18.655 mGy) , the DLP (289.78 to 968.241 mGy/cm), and mean effective doses were (4.34 to 14.5 mSv), in chest CTs the mean values of CTDI<sub>vol</sub> were (5.05 to 14.39mGy), the DLP were (202.84 to 499.098mGy/cm), and median effective doses were (2.85 to 6.97 mSv), in head CTs the mean values of CTDI<sub>vol</sub> were (42.4to 68.278mGy), the DLP were (781 to 1209.18mGy/cm), and effective doses were (1.636 to 2.528mSv). <strong>Conclusion:</strong> Regarding selected exams, CTDI, DLP and ED were found to be varied from low variations in head CT scan, to medium in chest CT scan and high variation in abdomen CTs among different CT scanners, The highest values of CTDI and DLP were noted in head CTs followed by abdomen, and the lowest were in chest CTs. The most factors affected the CT dose variations were the technical parameters settings, mainly the number of slices, however the scanner specifications reported some impact. Optimizing dose to a reliable standard for each anatomical part should be adjusting independently by each department according to the scanner characteristics, settings and patient factors.
48
Tanki, Nobuyoshi, Toshizo Katsuda, Rumi Gotanda, et al. "THE CONCEPT OF X-RAY CT DOSE EVALUATION METHOD USING RADIOCHROMIC FILM AND FILM-FOLDING PHANTOM." Radiation Protection Dosimetry 193, no. 2 (2021): 96–104. http://dx.doi.org/10.1093/rpd/ncab033.
Full textAbstract:
Abstract In this paper, we propose a novel radiochromic film (RCF)-based computed tomography (CT) dosimetry method, which is different from the method based on CT dose index. RCF dosimetry using Gafchromic QA2 films was performed using two lengths of film-folding phantoms. The phantom was exposed to X-ray CT through a single scan, while the RCF was sandwiched between the phantoms. We analysed the dose profile curve in two directions to investigate the dose distribution. We observed a difference in the dose distribution as the phantom size changed. Our results contradict with the results of previous studies such as Monte Carlo simulation or direct measurement. The ability to visually evaluate 2D dose distributions is an advantage of RCF dosimetry over other methods. This research investigated the ability of 2D X-ray CT dose evaluation using RCF and film-folding phantom.
49
Kim, Hyeonjin, Hyoyeong Lee, and Inchul Im. "Analysis and Evaluation of Computed Tomography Dose Index (CTDI) of Pediatric Brain by Hospital Size." Journal of the Korean Society of Radiology 10, no. 7 (2016): 503–10. http://dx.doi.org/10.7742/jksr.2016.10.7.503.
Full text
50
Brenner, David J., Cynthia H. McCollough, and Colin G. Orton. "It is time to retire the computed tomography dose index (CTDI) for CT quality assurance and dose optimization." Medical Physics 33, no. 5 (2006): 1189–91. http://dx.doi.org/10.1118/1.2173933.
Full text