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Dissertations / Theses on the topic 'Radiosurgery'
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1
Yun, Michael Jino. "Radiosurgery for Malignant Brain Tumors." VCU Scholars Compass, 1994. http://scholarscompass.vcu.edu/etd/5088.
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Radiosurgery using the Linear Accelerator or the Gamma Knife has proven to be an effective treatment modality for malignant brain tumors. In comparison to other treatments, radiosurgery can be performed on an outpatient basis and is noninvasive (Table 5). Due to the functional properties of radiosurgical devices, they are ideal for patients who are unable to undergo surgical removal of their brain tumors. The sharp dose drop—off beyond the tumor margin allows for high dosage tumor irradiation while sparing normal brain tissue. Many procedures that involve radiosurgery use it as a ”boost” therapy in conjunction with surgical resection and whole brain irradiation. ”Boost" therapy enhances the standard treatment procedure for malignant brain tumors.
Unfortunately, radiosurgery is not always able to halt the progression of malignant brain tumors. Patients with metastatic brain tumors usually succumb to systemic disease. Patients who have gliomas generally die due to the inability of local tumor control. However, the use of radiosurgery can contribute to increasing a patient’s quality of life. Often, treatment is followed by a decrease in corticosteroid administration and an improvement in a patient's neurological status. The future directions of radiosurgery could include the development and implementation of a randomized studies to determine a dose-volume protocol for gliomas and the different forms of metastases. Also, an investigation should be undertaken to determine whether the use of high (50 Gy or more) radiosurgical doses as the only treatment for gliomas and cerebral metastases would prove to be a more effective use than ”boost” therapy.
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Dubé, Frédéric. "Spiral irradiation in stereotactic radiosurgery." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0016/MQ55049.pdf.
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Dubé, Frédéric 1973. "Spiral irradiation in stereotactic radiosurgery." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29884.
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The aim of stereotactic radiosurgery is to deliver a high and uniform radiation dose to the target volume and a minimized dose to the surrounding healthy tissue. Various linac-based radiosurgical techniques are used clinically: multiple non-coplanar converging arcs, dynamic arc rotation, and conical rotation. The techniques differ in their beam distribution over the patient's head.<br>A study of the beam distribution characteristics for the clinical linac-based radiosurgical techniques is presented. Two spiral linac-based radiosurgical techniques are developed: the uniform dose-rate spiral irradiation and the dose-rate-weighted spiral irradiation. Both exhibit the same spiraling beam entry trace over the patient's head; however, they differ in their beam distribution along the spiral. The dose-rate-weighted spiral irradiation provides a uniform beam distribution over the 2pi solid angle available in radiosurgery.<br>The currently existing techniques and the spiral techniques are then compared using the cumulative dose-volume histogram (CDVH) tools available with the McGill Treatment Planning System (MPS). The dose-rate-weighted spiral technique leads to lower dose inhomogeneities within the target volume and better dose conformity within the target. Moreover, it also encompasses smaller volumes of tissue at all isodose levels with larger differences at low isodose levels. A conclusion is reached that the dose-rate-weighted spiral irradiation technique offers interesting advantages over the currently used clinical linac-based techniques.
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Bourque, Daniel. "Static conformal fields in stereotactic radiosurgery." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ37097.pdf.
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Schlaefer, Alexander. "Computer assisted planning for robotic radiosurgery." Berlin Logos-Verl, 2007. http://d-nb.info/988177684/04.
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Hu, Xiaoliang. "A New Gamma Knife Radiosurgery Paradigm: Tomosurgery." online version, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1170292131.
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Chua, T. T. Daniel. "Stereotactic radiosurgery as salvage treatment for locally recurrent nasopharyngeal carcinoma." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37223513.
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Otto, Karl. "3-dimensional anatomy-based verification in stereotactic radiosurgery." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0014/MQ37154.pdf.
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Auld, Lindsay. "Treatment dose verification in stereotactic radiosurgery quality assurance." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0015/MQ45883.pdf.
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Otto, Karl 1972. "3-dimensional anatomy-based verification in stereotactic radiosurgery." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27895.
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An on-line beam to target portal verification technique has been developed for stereotactic radiosurgery. Conventional radiosurgery employs a stereotactic frame in order to obtain sufficient spatial accuracy in dose delivery. Frame based verification methods attempt to ensure accurate target positioning with respect to the frame but they do not account for possible movement of the frame with respect to the anatomy and isocenter. We account for this possibility by superimposing digitally reconstructed radiographs (DRRs) over orthogonal edge detected digital portal image pairs. By developing a process for interactively manipulating the CT-data in three dimensions (rotations and translations) new DRRs are generated and overlaid with orthogonal portal images. This method is able to account for ambiguities in matching due to rotations and translations outside the imaging plane because of the availability of DRRs at any possible orientation. This matching procedure is performed using only the anatomy and is used in tandem with a fiducial marker array attached to the stereotactic frame. The method is evaluated using portal images simulated from patient CT-data and then tested using a radiographic head phantom. Results show that repositioning precision of the system is at the level required by stereotactic radiosurgery.
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Sixel, Katharina E. (Katharina Elisabeth). "Physical parameters of narrow photon beams in radiosurgery." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59890.
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Radiosurgery is a radiation treatment modality in which a high radiation dose (few 1000 cGy) is given to a small volume (few cm$ sp3$) within the patient's brain during a single treatment. The main physical characteristics of radiosurgery are narrow circular radiation beams, stringent requirements on the numerical ($ pm$2%) and spatial ($ pm$1 mm) accuracy of dose delivery to the target and the need for sharp dose fall-offs outside the target volume.<br>Physical aspects of radiosurgery based on isocentric linear accelerators (linacs) are presented. The equipment and techniques used in the measurement of various radiosurgical beam parameters are discussed. Also discussed is the accuracy of radiation beam delivery to the target, the calculation and measurement of 3-dimensional isodose distributions obtained from circular beams, and the production of cylindrical dose distributions with rectangular beams. It is shown from the physics point-of-view that linac-based radiosurgery is a viable alternative to radiosurgery with the commercially available Gamma unit.
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Oliveira, Silvana C. "Comparison of three linac-based stereotactic radiosurgery techniques." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19455.
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In this thesis, physical and biological aspects of three linear-accelerator-based stereotactic radiosurgery techniques, namely the dynamic rotation, static conformal beam, and intensity-modulated beam, are compared. Comparisons are carried out using simulated targets which include spheres, hemispheres and a C-shaped target wrapped around a critical structure, inserted within modified slabs of an Alderson Rando anthropomorphic phantom. The phantom is CT-scanned with a stereotactic frame, and the images are transferred to the treatment planning systems. The best possible treatment plans are generated for each simulated target and for each of the three techniques. Treatment plans are compared using both physical (homogeneity and conformity indices) and biological parameters (integral biologically effective dose, tumour control probability and normal tissue complication probability). Possible correlation between physical and biological parameters is investigated for the three techniques. Finally, some experiments are performed to explain the lack of correlation obtained when multiple isocenters are employed in the dynamic rotation technique for the treatment of irregular targets.
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Narayanan, Sridar 1966. "Image analysis for the assessment of stereotactic radiosurgery." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68229.
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This thesis describes an image-based system for analyzing dose distributions produced during treatment planning of stereotactic radiosurgery. A review of stereotaxy and radiosurgery, particularly for the treatment of arteriovenous malformations (AVMs), is presented. The stereotactic apparatus and linear accelerator-based irradiation techniques used at McGill University are described in some detail.<br>The image-dose analysis software, running on a UNIX workstation, is presented, including software utilities for the evaluation of radiosurgery treatment plans based on magnetic resonance (MR) images. The importance of dose-volume histograms (DVHs) in the assessment of treatment plans is discussed, and the software developed to generate DVHs is described.<br>A technique for the experimental verification of calculated three-dimensional (3D) dose distributions is presented. This computerized approach is based on stereotactic principles and uses a plastic phantom and radiotherapy verification film as the dosimeter. The results indicate that, with some improvements, this is a viable technique for the experimental validation of stereotactic 3D treatment planning software.
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Bercier, Yanic. "Image fusion for radiosurgery treatments of arteriovenous malformations." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82830.
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An interactive 3D target localisation and delineation tool has been developed for radiosurgery planning of arteriovenous malformations (AVMs). With this system, magnetic resonance (MR), MR angiography (MRA) and computed tomography (CT) volumes can be fused in stereotactic space. Stereotactic angiography (SA) images can be linked to the MRA volume by recovering the SA acquisition geometry. The MRA and SA images can be correlated (1) by ray-tracing through the MRA volume with the recovered SA acquisition geometry and overlaying the images onto the SA images and (2) by localising the AVM onto a volume rendered representation of the MRA with a 3D cursor and projecting its position onto the SA images. Target contours can then be drawn on the MRA/MR/CT images and simultaneously projected onto the SA images.<br>The plans of patients who had previously undergone radiosurgery at our institution employing SA images for localisation and MR images for delineation were investigated. MRA datasets were also acquired at the time of MR scanning employing the 3D TOF technique. Some ray-traced MRA images correlated well visually with the SA images, others presented inconsistencies which suggest that MRA should be used only as complement to SA images.<br>The role of the different modalities (M-RA, MR and SA) in the definition of target volumes is investigated by defining the target contours with different combinations of modalities within the interactive system. The target volumes drawn with different modalities were compared to a reference volume, drawn using MRA, MR and SA images, and presented underestimation and overestimation of target volumes ranging from 20% to 92% and from 3% to 40%.<br>The dosimetric implications of image fusion for target delineation are investigated by retrospective evaluation of the dose coverage of the reference target volume by the original treatment plan. Target coverage inferior to 60% of the reference target volumes by the original treatment plans was obtained for the patients. Treatment plan optimisation was performed to evaluate the possible dosimetric improvements resulting from image fusion for AVM target delineation. The plans were improved by employing three, eight and four isocentres for the 3 patients, and resulted in target coverage equal or superior to 98% for all three patients.
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Tozer-Loft, Stephen M. "Dose volume analysis in brachytherapy and stereotactic radiosurgery." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366100.
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Ashfaq, Awais. "Segmentation of Cone Beam CT in Stereotactic Radiosurgery." Thesis, KTH, Skolan för teknik och hälsa (STH), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193107.
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C-arm Cone Beam CT (CBCT) systems – due to compact size, flexible geometry and low radiation exposure – inaugurated the era of on-board 3D image guidance in therapeutic and surgical procedures. Leksell Gamma Knife Icon by Elekta introduced an integrated CBCT system to determine patient position prior to surgical session, thus advancing to a paradigm shift in facilitating frameless stereotactic radiosurgeries. While CBCT offers a quick imaging facility with high spatial accuracy, the quantitative values tend to be distorted due to various physics based artifacts such as scatter, beam hardening and cone beam effect. Several 3D reconstruction algorithms targeting these artifacts involve an accurate and fast segmentation of craniofacial CBCT images into air, tissue and bone. The objective of the thesis is to investigate the performance of deep learning based convolutional neural networks (CNN) in relation to conventional image processing and machine learning algorithms in segmenting CBCT images. CBCT data for training and testing procedures was provided by Elekta. A framework of segmentation algorithms including multilevel automatic thresholding, fuzzy clustering, multilayer perceptron and CNN is developed and tested against pre-defined evaluation metrics carrying pixel-wise prediction accuracy, statistical tests and execution times among others. CNN has proven its ability to outperform other segmentation algorithms throughout the evaluation metrics except for execution times. Mean segmentation error for CNN is found to be 0.4% with a standard deviation of 0.07%, followed by fuzzy clustering with mean segmentation error of 0.8% and a standard deviation of 0.12%. CNN based segmentation takes 500s compared to multilevel thresholding which requires ~1s on similar sized CBCT image. The present work demonstrates the ability of CNN in handling artifacts and noise in CBCT images and maintaining a high semantic segmentation performance. However, further efforts targeting CNN execution speed are required to utilize the segmentation framework within real-time 3D reconstruction algorithms.<br>C-arm Cone Beam CT (CBCT) system har tack vare sitt kompakta format, flexibla geometri och låga strålningsdos startat en era av inbyggda 3D bildtagningssystem för styrning av terapeutiska och kirurgiska ingripanden. Elektas Leksell Gamma Knife Icon introducerade ett integrerat CBCT-system för att bestämma patientens position för operationer och på så sätt gå in i en paradigm av ramlös stereotaktisk strålkirurgi. Även om CBCT erbjuder snabb bildtagning med hög spatiel noggrannhet så tenderar de kvantitativa värdena att störas av olika artefakter som spridning, beam hardening och cone beam effekten. Ett flertal 3D rekonstruktionsalgorithmer som försöker reducera dessa artefakter kräver en noggrann och snabb segmentering av kraniofaciala CBCT-bilder i luft, mjukvävnad och ben. Målet med den här avhandlingen är att undersöka hur djupa neurala nätverk baserade på faltning (convolutional neural networks, CNN) presterar i jämförelse med konventionella bildbehandlings- och maskininlärningalgorithmer för segmentering av CBCT-bilder. CBCT-data för träning och testning tillhandahölls av Elekta. Ett ramverk för segmenteringsalgorithmer inklusive flernivåströskling (multilevel automatic thresholding), suddig klustring (fuzzy clustering), flerlagersperceptroner (multilayer perceptron) och CNN utvecklas och testas mot fördefinerade utvärderingskriterier som pixelvis noggrannhet, statistiska tester och körtid. CNN presterade bäst i alla metriker förutom körtid. Det genomsnittliga segmenteringsfelet för CNN var 0.4% med en standardavvikelse på 0.07%, följt av suddig klustring med ett medelfel på 0.8% och en standardavvikelse på 0.12%. CNN kräver 500 sekunder jämfört med ungefär 1 sekund för den snabbaste algorithmen, flernivåströskling på lika stora CBCT-volymer. Arbetet visar CNNs förmåga att handera artefakter och brus i CBCT-bilder och bibehålla en högkvalitativ semantisk segmentering. Vidare arbete behövs dock för att förbättra presetandan hos algorithmen för att metoden ska vara applicerbar i realtidsrekonstruktionsalgorithmer.
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Sandström, Helena. "Contouring variability in radiosurgery - dosimetric and radiobiological implications." Licentiate thesis, Stockholms universitet, Fysikum, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-123252.
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The use of Stereotactic Radiation Therapy (SRT) employing one large fraction of radiation, as in stereotactic radiosurgery (SRS), or few fractions of high doses, has continuously increased due to the technical development and the progress in dose delivery complemented by the positive clinical experience. The success of stereotactic radiation therapy depends on many clinical, dosimetric and radiobiological factors. For SRS in particular, the delivery of a highly conformal dose distribution to the target in one fraction allowing at the same time the sparing of the normal tissue and the critical structures is part of the basic concept of the technique. Provided that the highly accurate radiosurgical equipment available today is used, planning and delivering the prescribed dose distribution is an achievable goal, and therefore the main issue to be solved is the definition of the target. As the target volume in radiosurgery is usually defined without margins, the success of the stereotactic approach critically depends on the accurate delineation of the target which could be identified as a factor of key importance. In addition, the delineation of the Organs At Risk (OAR) is also critical. The purpose of this work was to evaluate the current degree of variability for target and OAR contouring and to establish methods for analysing multi-observer data regarding structure delineation variability. A multi-center target and OAR delineation study was initiated. Two complex and six common cases to be treated with SRS were selected and subsequently distributed to centers around the world performing Gamma Knife® radiosurgery for delineation and treatment planning. The resulting treatment plans and the corresponding delineated structures were collected and analysed. Results showed a very high variability in contouring for four complex radiosurgery targets. Similar results indicating high variability in delineating the OAR and reporting the doses delivered to them were also reported. For the common radiosurgery targets however, a higher agreement in the delineation was observed, although lower than expected. The assessment of the quality of treatment planning for radiosurgery is usually performed with respect to the coverage of the target, the planning specificity, and dose to the sensitive structures and organs close to the target. However, physical dose conformity to the target does not guarantee the success of the treatment. The assessment of the plan quality should also be performed with respect to the clinical outcome expressed as probability of controlling the target that should be irradiated. In this respect, this study also aimed to create the framework for assessing the impact of the inaccuracy in delineating the target on the predicted treatment outcome for radiosurgery targets known for their high potential to invade the neighbouring normal tissue, using radiobiological models. In addition, radiobiological models have also been used to determine the tumour control probability accounting for the oxygenation for stereotactic radiation therapy targets. The results suggest that radiobiological modelling has the potential to add to the current knowledge in SRS by theoretically assessing the key factors that might influence the treatment outcome.
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Andisheh, Bahram. "Improving the therapeutic ratio of stereotactic radiosurgery and radiotherapy." Doctoral thesis, Stockholms universitet, Fysikum, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-81079.
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New methods of high dose delivery, such as intensity modulated radiation therapy (IMRT), stereotactic radiation therapy (SRT) or stereotactic radiosurgery (SRS), hadron therapy, tomotherapy, etc., all make use of a few large fractions. To improve these treatments, there are three main directions: (i) improving physical dose distribution, (ii) optimizing radiosurgery dose-time scheme and (iii) modifying dose response of tumors or normal tissues. Different radiation modalities and systems have been developed to deliver the best possible physical dose to the target while keeping radiation to normal tissue minimum. Although applications of radiobiological findings to clinical practice are still at an early stage, many studies have shown that sublethal radiation damage repair kinetics plays an important role in tissue response to radiation. The purpose of the present thesis is to show how the above-mentioned directions could be used to improve treatment outcomes with special interest in radiation modalities and dose-time scheme, as well as radiobiological modeling. Also for arteriovenous malformations (AVM), the possible impact of AVM network angiostructure in radiation response was studied.<br>Nya och förbättrade metoder för precisionsbestrålning, såsom intensitetsmodulerad strålbehandling (IMRT), stereotaktisk strålbehandling (SRT), stereotaktisk strålkirurgi (SRS) eller hadronterapi etc., gör det möjligt att leverera behandlingen i ett fåtal fraktioner med höga doser. Dessa behandlingmetoder kan ytterligare förbättras genom att (i) förbättra den fysikaliska dosfördelningen, (ii) optimera dosrater och fraktioneringsscheman eller (iii) modifiera dosresponsen hos tumörer eller normalvävnad. Olika strålmodaliteter och behandlingssystem har tagits fram för att kunna leverera bästa möjliga fysikaliska dosfördelning till targetvolymen samtidigt som dosen till frisk vävnad hålls så låg som möjligt. Även om användandet av radiobiologisk kunskap och modeller i klinisk rutin ännu är i sin linda så visar många studier att kinetiken för subletal reparation av strålskador har stor betydelse för strålresponsen. Syftet med denna avhandling är att visa hur dessa olika utvecklingsvägar kan användas för att förbättra behandlingsresultatet speciellt genom att studera vald strålmodalitet, dosrat och fraktioneringsschema samt radiobiologisk modellering. För arteriovenösa missbildningar (AVM) har även studerats hur strukturen hos angionätverket påverkar strålresponsen.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>
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Charpentier, Pierre E. "Dosimetric evaluation of four techniques used in stereotactic radiosurgery." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112386.
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The thesis presents a comparison of four techniques used for stereotactic radiosurgery, consisting of the static conformal beam, static cone-based, proton therapy, and the Gamma Knife techniques. The comparisons involved six test cases in which phantom target lesions were created in the center of the modified anthropomorphic RandoRTM head. The phantom lesions presented in the study were extreme irregular cases that ranged in shape and volume and were near a critical structure to receive minimal dose during treatment planning. The best treatment plans from each technique for all studies were selected and the extracted data was analyzed using physical and biological parameters. Correlations between integral biological effective dose (normal brain) and normal tissue complication probability were analyzed as a function of dose conformity (PITV), and correlations between tumor control probability and integral biological effective dose (tumor) as a function of dose homogeneity (MDPD) were analyzed, as well. These parameter pairings showed strong links. The static conformal beam and the proton SOBP techniques consistently provided low PITV and MDPD values for all cases, including the most irregular and complicated cases. Higher PITV and MDPD values, typically associated with static cone-based and the Gamma Knife techniques, were due to normal tissue and tumor tissue, respectively, being irradiated at higher dose levels than the prescribed dose. For these cases, as the PITV increased, the NTCP increased, as well, due to high doses created within the normal tissue found within the prescription isodose surface.
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Dimitriadis, Alexis. "Assessing the dosimetric and geometric accuracy of stereotactic radiosurgery." Thesis, University of Surrey, 2017. http://epubs.surrey.ac.uk/813888/.
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Stereotactic radiosurgery (SRS) is a non-invasive treatment predominantly used for the management of malignant and benign brain tumours. The treatment can be delivered by various platforms in a single fraction where a high dose of radiation is delivered to the target whilst the surrounding healthy tissue is spared. This requires a high degree of accuracy in terms of the dose level delivered but also in terms of geometric precision. The purpose of this work was to identify the variations of SRS practice in the UK and develop a novel method compatible with all practices, capable of assessing the accuracy of delivery. The motivation behind this e↵ort was to contribute to safety in SRS delivery, provide confidence through a quality assurance audit and form a basis to support standardisation in SRS. A national survey was performed to investigate SRS practices in the UK and to help guide the methodology of this thesis. This resulted to the development of a method for an end-to-end audit of SRS. This was based on an anthropomorphic head phantom with a medium sized target located centrally in the brain, in close proximity to the brainstem. This realistic patient scenario was presented to all 26 radiosurgery centres in the UK who were asked to treat it with SRS. The dose delivered was assessed using two novel commercially available radiation detectors, a plastic scintillator and radiochromic film. These detectors were characterised for measuring the dose delivered in SRS. Another established dosimetry system, alanine, was also used alongside these detectors to assess the accuracy of each delivery. The results allowed the assessment of SRS practices in the UK and the comparison of all centres that participated in the audit. The results were also used to evaluate the performance of the dosimeters used for the purposes of quality assurance measurements and audit.
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Jitprapaikulsarn, Suradet. "An Optimization-Based Treatment Planner for Gamma Knife Radiosurgery." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1109959500.
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Shihadeh, Fadi Easa. "Optimized and integrated alignment system for functional proton radiosurgery." CSUSB ScholarWorks, 2007. https://scholarworks.lib.csusb.edu/etd-project/3258.
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In this thesis work, a system for proton beam alignment was studied and optimized in many of its functional areas. The resulting system was named Positioning Alignment Control System (PACS). The PACS system is an integrated and efficient system as a result of the work done on it in the course of this thesis work.
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Wenner, Lisa Ellen. "Using regression techniques for the automated selection of radiosurgery plans." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/13706.
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Fox, Timothy Harold. "Computation and optimization of dose distributions for rotational stereotactic radiosurgery." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/32843.
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Hössjer, Simon. "3D/2D Image Registration for Patient Positioning in Stereotactic Radiosurgery." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170639.
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In the application of stereotactic radiosurgery for treatment of brain tumors it is imperative that patients are positioned with sub-millimetre accuracy so as to not damage surrounding healthy tissue during treatment. We investigate how feasible the technique of digitally reconstructed radiographs is as a registration method for patient positioning in this type of high-accuracy application. In particular, since most registration methods based on said technique only rely on two simultaneous projection angles seldom reaching high enough accuracy, we consider any arbitrary amount and observe its effects on the registration accuracy. Three different approaches are considered for how multiple projections can be combined into one single metric. The results seem to indicate that although computed tomography yields accuracies well within the boundaries for stereotactic radiosurgery, cone beam computed tomography in its current state does not. Possible reasons explaining the difference include problems with reconstruction artifacts in the model and inadequate metrics.<br>Inom tillämpningen av stereotaktisk strålkirurgi för behandling av hjärntumörer är det absolut nödvändigt att patienter positioneras inom millimeternoggrannhet för att undvika skada hos närliggande vävnad vid behandling. Vi undersöker hur trolig tekniken om digitaliserade återskapande röntgenbilder är som en registreringsmetod för patientpositionering i den här typen av mycket noggranna applikationer. Framförallt betraktas godtyckligt många projektionsvinklar och observerar dess effekt på registreringsnoggrannheten, eftersom de flesta tidigare presenterade registreringsmetoderna endast är baserade på två projektionsvinklar och sällan uppfyller det krav som ställs på noggrannhet. Tre olika tillvägagångssätt betraktas för hur flertalet projektionsvinklar kan kombineras till ett enda avståndsmått. Resultaten verkar tyda på att datortomografi medför noggrannheter väl inom ramen för stereotaktisk strålkirurgi, medan konstråledatortomografi i sitt nuvarande tillstånd inte verkar göra detta. Anledningar till denna olikhet tros vara problem med rekonstruktionsartefakter i modellen och otillräckliga avståndsmått.
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Chua, T. T. Daniel, and 蔡清淟. "Stereotactic radiosurgery as salvage treatment for locally recurrent nasopharyngeal carcinoma." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37223513.
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Josefsson, Marcus. "Robust Optimization for Radiosurgery under the Static Dose Cloud Approximation." Thesis, KTH, Optimeringslära och systemteori, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156415.
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This report investigates methods of optimization to make treatment plans in radiosurgery robust to spatial uncertainty, and attempts to determine whether they could be used with bene t in a Gamma Knife context. To make the problem mathematically feasible, regions of interest (ROIs) are approximated to move in a pre-computed static dose cloud, which in turn is estimated by methods of linear interpolation and linear approximation. The movements of ROIs are modeled by transforms, of which rigid, general affine, and a special case of non-affine transforms are treated. Of these, the rigid transforms are used to flexibly assess various properties of the robust optimization model; the a ne transforms to model the total geometric error of the Gamma Knife, excluding ROI delineation; and the non-affine transforms for initial modeling of the important delineation uncertainty. For the geometric errors, traditionally seen as small for the Gamma Knife, the robust treatment plans are seen to compare favorably to those obtained by non-robust optimization. Delineation errors are found to need careful modeling in order to avoid excessively conservative plans, which may harm normal tissue.
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Alexander, Dana J. "Dose accuracy of the CMS convolution algorithm for stereotactic radiosurgery." Diss., Online access via UMI:, 2009.
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Malkoc, Veysi. "Sequential alignment and position verification system for functional proton radiosurgery." CSUSB ScholarWorks, 2004. https://scholarworks.lib.csusb.edu/etd-project/2535.
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The purpose of this project is to improve the existing version of the Sequential Alignment and Position Verification System (SAPVS) for functional proton radiosurgery and to evaluate its performance after improvement .
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Poffenbarger, Brett A. "Viability of an isocentric cobalt-60 teletherapy unit for stereotactic radiosurgery." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0007/MQ44248.pdf.
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Sixel, Katharina E. (Katharina Elisabeth). "Measurements and Monte Carlo simulations of X-ray beams in radiosurgery." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41242.
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Radiosurgery is characterized by high radiation doses, delivered via small diameter radiation beams in a single session, placing stringent requirements on the numerical and spatial accuracy of dose delivery to the target volume within the brain. In this thesis, physical and clinical aspects of radiosurgery are discussed, including a method for the production of cylindrical dose distributions with rectangular beams using cylindrical dynamic rotation.<br>The measurements of radiosurgical x-ray beam parameters are presented. Monte Carlo simulations determine that a measured increase depth of dose maximum with increasing field size is a result of primary dose deposition in phantom for small diameter beams.<br>An analytical representation based on a curve-fitting process is developed to parametrize radiosurgical x-ray beam percentage depth doses as a function of depth in phantom, field diameter and beam energy using bi-exponential and polynomial functions.<br>Measurements of dose in the build-up region of x-ray beams ranging from 1 x 1 cm$ sp2$ to 30 x 30 cm$ sp2$ show that the depth of dose maximum increases rapidly with increasing field size at small fields, reaches a maximum around 5 x 5 cm$ sp2$ and then gradually decreases with increasing field size for large fields. Monte Carlo simulations attribute effect observed at large fields to the scatter contamination of the primary beam from the linac head. This scatter contamination is measured by a half-block technique and further experiments show that it consists of electrons originating in the flattening filter of the linac.
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Thakur, Varun. "Planning and delivery comparison of six Linac-based stereotactic radiosurgery techniques." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107888.
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This work presents planning and delivery comparison of linac-based SRS treatment techniques currently available for single lesion cranial SRS. In total, two dedicated SRS systems (Novalis Tx, Cyberknife) and a HI-ART TomoTherapy system with six different delivery techniques are evaluated. Four delivery techniques are evaluated on a Novalis Tx system: circular cones, dynamic conformal arcs (DCA), static non-coplanar intensity modulated radiotherapy (NCP-IMRT), and volumetric modulated arc therapy (RapidArc) techniques are compared with intensity modulation based helical Tomotherapy on the HI-ART Tomotherapy system and with non-isocentric, multiple overlapping based robotic radiosurgery using the CyberKnife system. Thirteen patients are retrospectively selected for the study. The target volumes of each patient are transferred to a CT scan of a Lucy phantom (Standard Imaging Inc., Middleton, WI, USA) designed for end-to-end SRS QA. In order to evaluate the plans, several indices scoring the conformality, homogeneity and gradients in the plan are calculated and compared for each of the plans. Finally, to check the clinical deliverability of the plans and the delivery accuracy of different systems, a few targets are delivered on each system. A comparison between planned dose on treatment planning system and dose delivered on Gafchromic EBT film (ISP, Wayne, New Jersey, USA) is carried out by comparing dose beam profiles, isodose lines and by calculating gamma index.<br>Cette étude présente la planification et la comparaison de livraison de doses de les techniques de traitement par accélérateur linéaire (linac) à base de radiochirurgie stéréotactique (RCS) actuellement disponibles pour la RCS des lésions crâniennes uniques. Au total, deux systèmes RCS (Novalis Tx, Cyberknife) et un système HI-ART TomoTherapy avec six techniques différentes de livraison de doses sont évalués. Trois techniques de livraison de doses d'un système Novalis Tx sont évalués: arcs dynamiques conformationnelles, radiothérapie avec modulation d'intensité statique non-coplanaire et les techniques de thérapie volumétrique par arc modulé (RapidArc) sont comparées avec la tomothérapie hélicoïdale par modulation d'intensité sur le système HI-ART TomoTherapy et la radiochirurgie robotique non-isocentrique à multiples chevauchements du système CyberKnife. Treize patients sont rétrospectivement sélectionnés pour l'étude. Les volumes cibles de chaque patient sont transférés sur un scan tomodensitométrique d'un fantôme Lucy (Standard Imaging Inc, Madison, WI, Etats-Unis) conçu pour l'assurance qualité des systèmes RCS. Afin d'évaluer les plans de traitements, plusieurs métriques de notation de conformalité telles que l'homogénéité et les gradients du plan de traitement sont calculées et comparées pour chacun des plans. Enfin, dans le but de vérifier la faisabilité de livraison clinique des plans de traitements et la précision de livraison des différents systèmes, quelques cibles sont délivrées sur chaque système. Une comparaison entre la dose prévue sur le système de planification du traitement et la dose délivrée sur un film de type GAFCHROMIC EBT (ISP, Wayne, New Jersey, USA) est effectuée par comparaison des profils de faisceaux de dose, des lignes de doses de même intensité (isodose) et en calculant l'indice gamma.
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Rojas, Villabona Alvaro Alexander. "Optimisation of planning and delivery methods for Gamma Knife Stereotactic Radiosurgery." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10048270/.
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The work presented in this dissertation is the response to a series of technical and clinical challenges encountered during the first four years of operations in the Gamma Knife Centre at Queen Square. These challenges, which are common to most contemporary Gamma Knife centres, were prospectively addressed and practical solutions were developed for the questions they posed. The dosimetric differences between the new convolution algorithm and the standard TMR 10 algorithm traditionally used for prediction of dose distribution in Gamma Knife Radiosurgery (GKR) were explored. It was demonstrated that inhomogeneity correction with the convolution algorithm results in a considerable but consistent dose shift compared to TMR 10. No significant difference in relative dose distribution was noted and it was concluded that a reduction of the prescription dose is necessary to obtain the same absolute dosimetric effect with the convolution algorithm. The stability of the stereotactic Leksell frame G in GKR was demonstrated using a comprehensive study design that involved repeated measurements of landmarks by two observers. The study provided reliable and realistic evidence of submillimetre stability of the stereotactic frame throughout the treatment procedure which is important for evaluation and development of new frameless radiosurgery systems. The technical feasibility of using a combination of three magnetic resonance angiography sequences (triple-MRA), instead of digital subtraction angiography (DSA), for visualisation and delineation of brain Arteriovenous Malformations (AVMs) for GKR targeting was demonstrated. Target volumes obtained using triple-MRA are on average 10% smaller than AVM targets obtained with the standard DSA planning method and this can potentially reduce the risk of adverse radiation effects (ARE). The treatment planning method described here has laid the way for a change in clinical practice that favours a less invasive treatment planning approach. The same principle of less invasive AVM imaging with triple-MRA was used at the post-GKR stage, when a DSA is performed to confirm AVM obliteration. Triple-MRA was found to consistently confirm or rule out residual AVMs in patients who had undergone GKR for brain AVMs, compared to DSA, and it can also be reliably used for characterisation of residual AVMs. The use of triple-MRA as a first line for assessment of obliteration after GKR is recommended.
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Cadman, Patrick F. (Patrick Frank). "Target localization and treatment set-up verification in linear accelerator-based radiosurgery." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61344.
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The stringent demands for accuracy in radiosurgery impinge on all aspects of the radiosurgical procedure. A computer program, used to determine target coordinates from planar stereotactic image pairs, has been developed. Digital subtraction angiography images, obtained with a localizer attachment affixed to the stereotactic frame, are analyzed with the program for the localization of certain malformations. During treatment set-up verification, the center of the radiation distribution is determined using portal linear accelerator images of the collimated radiosurgery beam, with the patient in the final treatment position and without removal of the radiosurgical collimator. A custom portal localizer attachment has been developed in-house for this purpose. Localization results obtained with a test phantom show a maximum deviation of 0.4 mm from the known target locations. The program has also been shown to be effective in detecting a misalignment between a localized target and the treatment radiation center during set-up verification.
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Gianolini, Stefano. "Comparative treatment planning and dosimetry for stereotatic radiosurgery: Gamma knife versus adapted LINAC /." Zürich : ETH, 2006. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16814.
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Robar, James L. "Film dosimetry and three-dimensional verification of conformal dose distributions in stereotactic radiosurgery." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0019/NQ48701.pdf.
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Bercier, Yanic. "A multimodality image fusion and localisation system for radiosurgery treatments of arteriovenous malformations /." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33379.
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A multimodality image fusion and localisation system for radiosurgery treatments of arteriovenous malformations (AVM) has been developed and validated. Within this system, three-dimensional magnetic resonance angiography (MRA) and two-dimensional digital subtraction angiography (DSA) vasculature information is combined with three-dimensional magnetic resonance (MR) and/or computed tomography (CT) anatomical information in order to benefit from the functionality of all modalities. MRA/MR/CT datasets are fused, and linked to the DSA images. The consistency of the linking procedure is verified by correlation of the DSA images with two-dimensional ray-traced projections of the MRA datasets. Organ contours are drawn on the MRA images, simultaneously visualised on their MR/CT counterparts, and projected onto the DSA images for visual feedback. This procedure allows users to incorporate both vascular and anatomical information in the three-dimensional target localisation and delineation process. Patient examples illustrating the utility of the system are presented.
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Gavriliouk, Elena O. [Verfasser]. "Unequal Sphere Packing Problem in the Context of Stereotactic Radiosurgery / Elena O Gavriliouk." Aachen : Shaker, 2007. http://d-nb.info/1170527167/34.
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Svensson, Jenni. "Multiobjective optimization in radiosurgery : How to approximate and navigate on the Pareto surface." Thesis, KTH, Optimeringslära och systemteori, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145133.
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Cancer is a common cause of death worldwide and radiotherapy is one of the treatments used. Since treatment planning is a time consuming matter for the radiation therapist, a way to decrease the time spent finding the plan would be an improvement. This can be achieved by precalculating a number of optimal plans and then choosing among these in real-time. In this thesis a dual algorithm for approximation of the Pareto optimal plans suggested by Bokrantz and Forsgren, was adapted to the parameters of the Leksell Gamma Knife®. A Graphical User Interface was also created, based on the navigation tool described by Monz et al to enable choosing among the pre-calculated dose plans. The computational time of the algorithm was investigated and the dimensionality of the solutions and Pareto optimal points were looked at to see if it might be possible to reduce the number of dimensions to speed up computations. Although no certain conclusions can be drawn about dimensionality reduction, I found no reason to rule that possibility out. It was also confirmed that there is reason to keep the number of objectives low to get a better approximation.<br>Cancer är en allt vanligare dödsorsak i världen och strålterapi är en vanlig behandlingsmetod. Att ta fram en strålbehandlingsplan är en tidskrävande process för den ansvarige sjukhusfysikern eller läkaren. Ett sätt att korta ner denna tid är att förberäkna ett antal optimala behandlingsplaner och sedan välja mellan kombinationer av dessa i realtid. Planerna som tas fram med hjälp av en dual algoritm föreslagen av Bokrantz och Forsgren, är anpassade till Leksell Gamma Knife®. Ett grafiskt verktyg har skapats för att navigera mellan de förberäknade planerna, baserat på navigeringsverktyget beskrivet av Monz et al. Beräkningstiden för att ta fram planerna har studerats, tillsammans med olika faktorer som påverkar den. I anknytning till detta gjordes en enklare dimensionsanalys av lösningarna och de Pareto-optimala punkterna för att se om det är möjligt att reducera antalet dimensioner för att snabba upp beräkningstiden. Inga långtgående slutsatser kan dras angående detta, men möjligheten går inte att utesluta. Slutsatsen att försöka hålla antalet målfunktioner lågt för att få en så bra approximation som möjligt bekräftades
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Courter, Erik Joseph-Leonard. "Use of ClearView Gel Dosimeter for Quality Assurance and Testing of Stereotactic Radiosurgery." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1466417256.
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Neupane, Mahesh Raj. "Optimization of a sequential alignment verification and positioning system (SAVPS) for proton radiosurgery." CSUSB ScholarWorks, 2005. https://scholarworks.lib.csusb.edu/etd-project/2784.
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Functional proton-beam stereotactic radiosurgery requires sub-millimeter alignment accuracy. A patient tracking system called Sequential Alignment and Position Verification System (SAVPS) is under development at Loma Linda University Medical Center. An optical positioning system (OPS), manufactured by Vicon Peak, has been chosen to verify the correct alignment of the target with the proton beam axis. The main objective of this thesis is to optimize an existing version of SAVPS by conducting error analysis. An image processing algorithm was developed and applied to estimate the error introduced by the Patient Positioning System (PPS) in order to derive the true error of the SAVPS.
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Tze, Mei-yu Jadie. "Is waiting time a quality service indicator for radiotherapy treatment? : the effect of waiting time on local tumour control for nasopharyngeal carcinoma patients in Hong Kong /." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36887328.
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Massager, Nicolas. "Influence de la distribution de dose d'irradiation dans la variation de l'effet radiobiologique du traitement radiochirurgical par Gamma Knife." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210380.
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La radiochirurgie par Gamma Knife constitue une modalité thérapeutique reconnue de certaines affections cérébrales. Le traitement se base sur l’administration d’un rayonnement focalisé au niveau d’une cible intracrânienne. L’efficacité de ce traitement repose sur la délivrance d’une dose d’irradiation efficace au sein d’un volume-cible associé à la délivrance d’une dose d’irradiation négligeable à l’extérieur de ce même volume-cible. En pratique, la dose d’irradiation administrée à l’intérieur du volume-cible n’est pas distribuée de manière homogène, et la dose d’irradiation reçue par les tissus situés en-dehors du volume-cible n’est pas nécessairement faible. Notre travail est basé sur l’hypothèse que l’imperfection de la distribution de la dose d’irradiation au sein du volume-cible et en-dehors de celui-ci peut être responsable des échecs et des complications rencontrées en radiochirurgie. Dans deux modèles cliniques de traitement radiochirurgical, le schwannome vestibulaire et la névralgie du trijumeau, nous avons montré qu’il existait une relation entre les paramètres de distribution de dose d’irradiation et certains résultats du traitement radiochirurgical par Gamma Knife de ces pathologies. Nous avons développé deux modèles expérimentaux d’irradiation radiochirurgicale de rats, l’un ciblé sur le striatum et l’autre sur le nerf trijumeau, permettant d’analyser les conséquences histologiques des variations de la distribution de dose à l’intérieur du volume-cible ainsi qu’à distance de celui-ci. Nous avons démontré que la réponse radiobiologique des tissus irradiés était fortement dépendante de ce paramètre dosimétrique, et que ce dernier constituait une donnée de la planification chirurgicale aussi importante que la dose de prescription. Nous avons corrélé ces résultats avec certaines observations réalisées dans d’autres indications de traitement radiochirurgical ainsi que dans l’analyse histologique de tumeurs traitées par Gamma Knife. Ces études mettent en évidence le rôle important joué par l’optimalisation de la distribution de la dose d’irradiation dans l’amélioration des résultats cliniques du traitement radiochirurgical. Les valeurs optimales de la distribution de dose dans les différentes indications de traitement radiochirurgical doivent être recherchées, et les différentes méthodes mises à notre disposition lors de la planification dosimétrique pour améliorer la distribution de dose doivent être utilisées avec discernement pour obtenir la dosimétrie radiochirurgicale la plus parfaite possible.<br>Doctorat en sciences médicales<br>info:eu-repo/semantics/nonPublished
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TAKAHASHI, HIROSHI, CHISA HASHIZUME, TAKAHIKO TSUGAWA, YOSHIMASA MORI, and TATSUYA KOBAYASHI. "PROGNOSTIC FACTORS FOR TUMOR RECURRENCE AFTER GAMMA KNIFE RADIOSURGERY OF PARTIALLY RESECTED AND RECURRENT CRANIOPHARYNGIOMAS." Nagoya University School of Medicine, 2012. http://hdl.handle.net/2237/16031.
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Milroy, Desmond. "Validation of a commercial Monte Carlo algorithm for stereotactic radiosurgery and stereotactic body radiation therapy." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110472.
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This thesis aimed to validate the Monte Carlo (MC) algorithm in BrainLab's iPlan treatment planning system, used in conjunction with stereotactic radiosurgery (SRS) mode of the Varian Novalis TX linear accelerator for clinical use. Specifically, the iPlan algorithm was "benchmarked" by comparing results obtained with a BEAMnrc model developed for the Novalis TX's SRS mode. The BEAMnrc model was obtained by modifying an existing model for a Varian linac to include the different SRS flattening filter and the high definition 120 leaf multi-leaf collimator (HD120 MLC) of the Novalis TX. Characterization of the source model used a recently published procedure to fit beam energy, source size and angular spread, and an existing BEAMnrc Monte Carlo component module (DYNVMLC) was reprogrammed to model the HD120 MLC of the Novalis TX linac. For the latter, the interleaf air gap and leaf density were adjusted such that simulations matched interleaf leakage profiles measured with film. Validation of the iPlan MC algorithm was accomplished through comparisons between both MC codes and film measurements for MLC defined fields, depth dose curves of square fields incident on heterogeneous slab phantoms, and more clinically realistic plans incident on a Lucy® stereotactic QA phantom and a Rando® head phantom. The source characterization procedure and the modeling of the HD120 MLC were successful, with subsequent simulations performing well compared to measurements of output factors, profiles in water and dose planes of MLC defined fields. Some discrepancies were observed between either MC code and film measurements, but calculations with iPlan MC and EGSnrc MC codes agreed well with each other in all cases. These results suggest that the iPlan Monte Carlo dose calculation algorithm is capable of accurately predicting radiation dose for complex fields in heterogeneous media.<br>Ce mémoire visait à valider l'algorithme Monte Carlo (MC) dans le cadre du système de planification de traitement iPlan de BrainLab où il est conjointement utilisé avec le mode radiochirurgical stéréostatique (SRS) de l'accélérateur linéaire Novalis TX de Varian. Plus particulièrement, l'algorithme iplan a été validé en comparant les résultats obtenus avec un modèle BEAMnrc du mode SRS de Novalis TX. Le modèle BEAMnrc a été créé en modifiant un modèle existant d'accélérateur Varian afin d'y inclure le filtre compensateur SRS et le collimateur multilames de haute définition de Novalis TX (HD120MLC). La caractérisation de la source a utilisé une procédure récente pour ajuster l'énergie, la taille et l'ouverture angulaire de la source. Par ailleurs, un module multilames de BEAMnrc existant (DYNVMLC) a été reprogrammé pour simuler le collimateur multilames de haute définition (HD120MLC). Pour ce dernier, l'écart entre les lames et la densité des lames ont été ajustés de sorte que les simulations correspondent aux profils de fuites interlames mesurées par films. La validation de l'algorithme iPlan a été réalisée par comparaisons entre les deux codes MC et des mesures de films pour des champs définis par le collimateur multilames, pour des courbes de la dose en profondeur de champs carrés administrés sur des fantômes hétérogènes et de plans plus réalistes du point de vue clinique administrés sur un fantôme stéréostatique Lucy® et un fantôme de tête Rando®. La procédure de caractérisation de la source et la modélisation du collimateur multilames (HD120MLC) ont été réussies ainsi que les simulations ultérieures correspondaient bien aux mesures des facteurs d'ouverture, des profiles dans l'eau et des distributions de dose des champs définis par le collimateur multilames. Des différences ont été observées s entre les codes MC et les mesures de films, mais les calculs avec les codes IPlan MC et EGSnc correspondaient bien dans tous les cas. Ces résultats suggèrent que l'algorithme MC de Iplan peut prédire précisément les doses de rayonnement pour des champs complexes dans des medias hétérogènes.
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Morales, Johnny Estuardo. "Advances in very small x-ray field dosimetry for circular cones used in stereotactic radiosurgery." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/133137/1/Johnny_Morales_Thesis.pdf.
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This project presents recent advances in small field dosimetry for radiosurgery treatments with Brainlab circular cones using 6 MV x-rays. The specific advances included: the use of a new microDiamond detector, the use of radiochromic film and OSLD detectors with an extrapolation technique, skin dose measurements and Monte Carlo simulation of radiosurgery treatments. There is limited published data on the output factor for the 4 mm circular cone. This thesis provides methodology and guidelines on how to perform such difficult measurements.
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HASHIZUME, CHISA, TATSUYA KOBAYASHI, YUTA SHIBAMOTO, TAKAHIKO TSUGAWA, MASAHIRO HAGIWARA, YOSHIMASA MORI, and HISATO NAKAZAWA. "Useful Base Plate to Support the Head During Leksell Skull Frame Placement in Gamma Knife Perfexion Radiosurgery." Nagoya University School of Medicine, 2014. http://hdl.handle.net/2237/19481.
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Toreti, Dalila Luzia. "Aceite, comissionamento e controle de qualidade em radiocirurgia." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-23092011-155440/.
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A Radiocirurgia Estereotática é a técnica de tratamento que usa feixes estreitos de radiação focalizados com grande exatidão em uma lesão pequena. A introdução dos colimadores micro multi-lâminas (mMLC) permite que essa técnica alcance um maior grau de conformação de dose na lesão alvo, possibilitando uma menor irradiação das estruturas críticas e dos tecidos normais. Este trabalho visa apresentar os resultados dos testes de aceite e do comissionamento de um acelerador linear Varian ® 6EX dedicado à Radiocirurgia, associado com o colimador multi-lâminas da BrainLab ® instalado no Hospital das Clínicas da Faculdade de Medicina da USP (HC-FMUSP) e estabelecer um Programa de Garantia de Qualidade que seja exequível para os serviços que pretendem implantar essa técnica especial. Os resultados dos testes de aceitação mostraram-se coerentes e satisfatórios com as especificações definidas pelo fabricante e os testes de comissionamento ficaram dentro das recomendações internacionais. Os testes e as medidas que compõem o processo de controle de qualidade devem ser específicos para cada unidade de tratamento, assim como a necessidade, a frequência e os níveis de tolerância.<br>Stereotactic Radiosurgery is a treatment technique that uses narrow beams of radiation focused with great accuracy in a small lesion. The introduction of micro multileaf collimators (mMLC) allows this technique to reach a higher degree of dose conformation of the target lesion allowing a smaller irradiation of critical structures and normal tissues. This paper presents the results of the acceptance tests and commissioning of a Varian ® 6EX linear accelerator dedicated to radiosurgery associated with the BrainLab ® micro multileaf collimator installed in the Hospital das Clínicas da Faculdade de Medicina da USP (HC-FMUSP) and establish feasible quality assurance program for the services that employ this special technique. The results of the acceptance tests were satisfactory and are willing with the specifications provided by the manufacturer and the commissioning tests were within the international recommendations. The tests and measures that are part of quality control process should be specific to each treatment unit, and the need, frequency and levels of tolerance.
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Winnenburg, Holger. "Qualitätssicherung in der Strahlentherapie spezifische Untersuchungen zur langzeitlichen Konstanz dosimetrischer und geometrischer Parameter beim Einsatz von Radiosurgery-Software /." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970184905.
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antonio, santacroce Verfasser], Hans-Jakob [Gutachter] [Steiger, and Jörg [Gutachter] Schipper. "The role of radiosurgery for the management of benign intracranial meningiomas / santacroce antonio ; Gutachter: Hans-Jakob Steiger, Jörg Schipper." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2018. http://d-nb.info/1149895683/34.
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