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1
Coles, Charlotte E. "Development of three-dimensional radiotherapy techniques in breast cancer." Thesis, University of Leicester, 2005. http://hdl.handle.net/2381/29491.
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Radiotherapy following conservation surgery decreases local relapse and death from breast cancer. Currently, the challenge is to minimise the morbidity caused by this treatment without losing efficacy. Despite many advances in radiation techniques in other sites of the body, the majority of breast cancer patients are still planned and treated using 2-dimensional simple radiotherapy techniques. In addition, breast irradiation currently consumes 30% of the UK's radiotherapy workload. Therefore, any change to more complex treatment should be of proven benefit. The primary objective of this research is to develop and evaluate novel radiotherapy techniques to decrease irradiation of normal structures and improve localisation of the tumour bed. I have developed a forward-planned intensity modulated (IMRT) breast radiotherapy technique, which has shown improved dosimetry results compared to standard breast radiotherapy. Subsequently, I have developed and implemented a phase III randomised controlled breast IMRT trial. This National Cancer Research Network adopted trial will answer an important question regarding the clinical benefit of breast IMRT. It will provide DNA samples linked with high quality clinical outcome data, for a national translational radiogenomics study investigating variation in normal tissue toxicity. Thus, patients with significant late normal tissue side effects despite good dose homogeneity will provide the best model for finding differences due to underlying genetics. I evaluated a novel technique using high definition free-hand 3-dimensional (3D) ultrasound in a phantom study, and the results suggested that this is an accurate and reproducible method for tumour bed localisation. I then compared recognised methods of tumour bed localisation with the 3D ultrasound method in a clinical study. The 3D ultrasound technique appeared to accurately represent the shape and spatial position of the tumour cavity. This tumour bed localisation research facilitated protocol development of a proposed national breast radiotherapy trial investigating IMRT and partial breast irradiation.
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Chung, Eunah. "Development of radiation dosimetry techniques for non-standard beam radiotherapy." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117004.
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Use of composite non-uniform radiation fields, which consist of a multitude of small fields, is very common in modern radiotherapy techniques. The conventional reference dosimetry protocols, however, use a 10 × 10 cm2 field as the reference machine calibration condition. The purpose of this work is to develop new, direct absorbed dose calibration methods for modern radiotherapy techniques that use static and composite nonstandard fields. An IAEA-AAPM international working group [Med. Phys. 35:5179–5186 (2008)] proposed a new formalism and introduced two intermediate fields, machine specific reference (msr) field fmsr and plan-class specific reference (pcsr) field fpcsr, for reference dosimetry of static and composite nonstandard fields, respectively. In the new formalism, correction factors which account for the difference in chamber calibration conditions between the reference field and msr field k^fmsr,fref_Qmsr,Q , pcsr field k^fpcsr,fref_Qpcsr,Q or clinical field k^fclin,fref_Qclin,Q were defined. This thesis focuses on the characterization of these correction factors. The dosimetry techniques to accurately measure the absorbed dose to water in nonstandard fields were established using four different radiation detectors, for which collecting volumes are radiologically water-equivalent. The characteristics of each radiation detector response were thoroughly investigated. Dose measurementin a nonstandard field normalized to that in the reference 10 × 10 cm2 field can be performed with an uncertainty of 0.2–0.3% when the dose distribution in the reference measurement region is homogeneous. Correction factors k^fmsr,fref_Qmsr,Q and k^fpcsr,fref_Qpcsr,Q were measured for one static nonstandard field and two different composite nonstandard fields, respectively, using different types of air-filled ionization chambers. Using the established dosimetry techniques, the k^fpcsr,fref_Qpcsr,Q were measured for different composite nonstandard fields which deliver various dose distributions in the reference measurement region. This work proved that the values of k^fpcsr,fref_Qpcsr,Q depend on the dose heterogeneity over the chamber collecting volume. Based on the measurement results, guidelines were suggested to select a new intermediate field for reference dosimetry of composite nonstandard fields. Finally, the IAEA-AAPM new formalism with values of k^fclin,fref_Qclin,Q obtained by experiments and MC methods was applied to reference dose measurement of clinical composite nonstandard fields using a calibrated air-filled ionization chamber. The corrected measured dose for each clinical field was compared with dose calculated using clinical treatment planning software or Monte Carlo methods. It was found that the accurate positioning of the reference detector and air-filled ionization chamber becomes more important when the dose heterogeneity in the reference measurement region increases. In conclusion, this thesis provides a method for accurate dose measurements in static and composite nonstandard fields. This work will help pave the way to improve the dosimetric consistency in these dynamic modern radiotherapy techniques.L'utilisation de champs de rayonnement composes non uniformes, qui consistent en une multitude de petits champs, est tres commune dans les techniques modernes de radiotherapie. Cependant, les protocoles de dosimetrie de reference conventionnels utilisent un champ standard de 10×10 cm2 pour calibrer les appareils. Le but de ce travail est de developper de nouvelles methodes de calibration de la dose absorbee pour des techniques modernes de radiotherapie, ce en utilisant autant des champs statiques que des champs composes non standards. Le groupe de travail AIEA-AAPM a propose un nouveau formalisme qui introduit deux champs intermediaires, soient le champ specifique a l'appareil (fmsr) et le champ specifique au plan de traitement (fpcsr), ce pour la dosimetrie de reference des champs statiques et des champs composes non standards, respectivement. Dans ce nouveau formalisme, des facteurs de corrections ontete definis afin de tenir compte des conditions de calibration de la chambre qui different entre le champ de reference et les champs fmsr, fpcsr ainsi que les champs cliniques (fclin). Ces facteurs sont respectivement d´efinis ainsi: k^fmsr,fref_Qmsr,Q , k^fpcsr,fref_Qpcsr,Q et k^fclin,fref_Qclin,Q . Cette these comporte sur la caracterisation exprimentale de ces facteurs de correction. Les techniques de dosimetrie visant a mesurer precisement la dose absorbe dans l'eau pour des champs non standards ont ete etablies en utilisant quatre differents detecteurs de radiation, chacun ayant un volume sensible radiologiquement equivalent a l'eau. Les caracteristiques de chaque detecteur ont ete approfondies. Les mesures de dose dans un champ non standard normalise a un champ de reference de 10×10 cm2 peuvent etre obtenues avec une incertitude de 0.2-0.3% lorsque la distribution de dose dans la region de mesure de reference est homogene. Les facteurs de correction k^fmsr,fref_Qmsr,Q et k^fpcsr,fref_Qpcsr,Q ont ete mesures pour un champ statique non standard et pour deux differents champs composes non standards, respectivement, en utilisant differents types de chambres d'ionisation a air. En utilisant les techniques de dosimetries etablies, les k^fpcsr,fref_Qpcsr,Q ont ete mesures pour plusieurs champs composes non standards qui produisent diff´erentes distributions de dose dans la region de mesure de reference. Ce travail demontre que les valeurs de k^fpcsr,fref_Qpcsr,Q d´ependent de l'heterogeneite de la dose dans le volume sensible de la chambre. Base sur les resultats des mesures, des lignes de conduite sont suggereespour determiner un champ intermediaire necessaire a la dosimetrie de reference des champs composes non standards. Finalement, le nouveau formalisme de l'AIEA-AAPM a ete applique a des mesures de dose de reference de champs composes non standards cliniques avec les valeurs k^fclin,fref_Qclin,Q obtenues experimentalement et avec des methodes Monte Carlo pour une chambre d'ionisation a air etalonnee. La dose mesuree et corrigee pourchacun des champs a ete comparee avec la dose calculee en utilisant un logiciel de planification de traitement ou des methodes Monte Carlo. Il a ete determine que la precision du positionnement du detecteur de reference ainsi que celui de la chambre d'ionisation a air devient plus important lorsque l'heterogeneite de dose dans la regionde mesure augmente. En conclusion, cette these fournit une methode precise de mesure de la dose absorbee pour des champs statiques et des champs compose non standards. Ce travail aidera a ameliorer la coherence des methodes dosimetrique appliquables aux techniques modernes de radiotherapie.
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Fenwick, John David. "Biological modelling of pelvic radiotherapy : potential gains from conformal techniques." Thesis, Institute of Cancer Research (University Of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322314.
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Ding, George X. (George Xiao) Carleton University Dissertation Physics. "An investigation of radiotherapy electron beams using Monte Carlo techniques." Ottawa, 1995.
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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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Md, Radzi Yasmin. "Development of techniques for verification of advanced radiotherapy by portal dosimetry." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/115505/.
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This research work is related to the development of an enhanced method for the treatment verification of Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT). Such advanced treatment techniques require accurate verification procedures to ensure treatments are delivered as correctly as possible. This work focused on the use of the Varian aS1000 Electronic Portal Imaging Device (EPID) with Dosimetry Check software-based verification system. This EPID-based patient dose verification had been widely discussed and proposed as a way to achieve treatment delivery accuracy and patient safety, and as an ‘in vivo’ verification technique that helps to avoid or minimise dosimetric errors. In this work, a novel matrix-based software method to correct for backscatter effects from the Varian aS1000 EPID support arm has been developed. The methodology allows a reliable quantification of the backscatter effect to be applied directly to the Dosimetry Check calibration and verification system. This process includes the use of a clinical treatment planning system (Oncentra MasterPlan, Nucletron) to calculate predicted dose distribution within a phantom or patient, which may be compared to the dose reconstructed by Dosimetry Check. It has been demonstrated that the developed method can be applied to both ‘pre-treatment’ and ‘on treatment’ portal dosimetry for IMRT Head-and-Neck. The Gamma Index Method confirmed excellent validation rates of 97% (3%/3mm) and 95% (5%/3mm) for the ‘pre-treatment’ and ‘on treatment’ approach respectively. Pre-treatment verification of VMAT Head-and Neck treatment also reported excellent validation rates of 96% (3%/5mm). In addition, a convenient way to use the developed methodology within Dosimetry Check software was also piloted and tested. This presents an opportunity of future clinical implementation of the techniques developed in this investigation.
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Khadija, Murshed. "A clinical comparison and analysis between conventional MLC based and solid compensator based IMRT treatment techniques [electronic resource] /." Toledo, Ohio : University of Toledo, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=mco1264434257.
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Thesis (M.S.)--University of Toledo, 2009."In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Title from title page of PDF document. Bibliography: p. 34-35.
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Tse, Ka-ho, and 謝家豪. "A comparison of contralateral breast dose from primary breast radiotherapy using different treatment techniques." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206498.
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Breast cancer is the most common cancer among women worldwide. Millions of new breast cancer cases are diagnosed every year, accounting for one-tenth of all new cancer cases. Because of the proof of equivalent efficacy between breast-conserving therapy (BCT) plus radiotherapy and mastectomy, increasing number of patients received breast irradiation during the past three decades, and radiotherapy plays a more and more important role in managing breast cancer. With the advancement of technology, the radiotherapy treatment techniques changed from conventional wedged technique to intensity modulated radiotherapy (IMRT), resulting in an improvement in the dose homogeneity. Regardless of the treatment techniques, peripheral dose to the contralateral breast is inevitable. The possibility of the peripheral dose causing contralateral breast cancer (CBC) has re-attracted the interest. However, the variation of the peripheral dose with different treatment techniques has not been well identified. Thus this study aims to compare the contralateral breast dose from the primary breast irradiation using various radiotherapy treatment techniques and types of shielding.
Six treatment plans by different treatment techniques, including paired physical wedges (PW-P), a lateral physical wedge only(PW-L), paired enhanced dynamic wedges (EDW-P), a lateral enhanced dynamic wedge only(EDW-L), field-in-field tangential opposing (TO-FiF), and inverse-planned intensity modulated radiotherapy (IMRT-IP), were generated using a female Rando phantom. The phantom was treated by all plans, and 15 metal oxide semiconductor field effect transistor(MOSFET)detectors on the surface and inside the contralateral breast were utilized for measuring the contralateral breast dose for each plan. Measurement was repeated with the application of 0.2, 0.3 and 0.5cm lead sheets or 0.5 and 1cm superflab (SF) on the TO-FiF to demonstrate the effect of shielding on the contralateral breast dose.
The measured contralateral breast doses were: 2.05Gy for PW-P, 1.44Gyfor PW-L, 1.51Gyfor EDW-P, 1.52Gyfor EDW-L, 1.25Gyfor TO-FiF, and 1.17Gyfor IMRT-IP, corresponding to 2.35% to 4.11% of total dose. PW-P producedthe highest contralateral breast dose while IMRT-IP producedthe lowest. For the addition of shielding, the doses were: 1.25Gy for no shielding, 0.65Gy for 0.2cm lead, 0.61Gy for 0.3cm lead, 0.49Gy for 0.5cm lead, 0.76Gy for 0.5cm SF, and 0.72Gy for 1cm SF. Lead sheet with 0.5cm thickness most effectively reduced the contralateral breast dose by 60%.All techniques showed that the surface dose was much higher than the dose at depth, and the dose dropped exponentially from the surface to the internal. Low energy radiation constitutes a large portion of the contralateral breast dose, so all types of shielding could decrease the surface dose effectively, but not the internal dose. The radiation-induced CBC risks were estimated to be about 0.77% to 1.36%.
To conclude, it is important that the contralateral breast dose to patients, especially those under 45, is maintained minimal. Therefore, TO-FiF or IMRT-IP are recommended to be the treatment of choices. The used of shielding, either lead or SF, is also advisable.published_or_final_version
Diagnostic Radiology
Master
Master of Medical Sciences
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Viviers, Emma Victoria. "A comparison of radiotherapy techniques for the irradiation of the whole scalp." Diss., University of Pretoria, 2010. http://hdl.handle.net/2263/25749.
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Wu, Wing-cheung Vincent, and 胡永祥. "Dose analysis of 2-dimensional and 3-dimensional radiotherapy techniques in the treatment of nasopharyngeal carcinoma." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31220149.
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Fong, Raymond, and 方思行. "Effects of different radiation therapy techniques on swallowing function in individuals with nasopharyngeal cancer." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196497.
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Nasopharyngeal cancer (NPC) is more common in the Southern China region than the rest of the world. Radiation therapy (RT) is the contemporary and standard treatment for nasopharyngeal cancer. Chronic complications arise from RT including hearing loss, xerostomia, trismus and dysphagia. Previous research has shown that dysphagia is prevalent in irradiated NPC patients. Radiation therapy techniques have improved in the last decade with the emergence of Intensity Modulated Radiation Therapy (IMRT), which allows more precise radiation beams directed at the tumor. In turn, it should also allow greater sparing of surrounding structures that are vital for preservation of swallowing function. This study was designed to investigate the difference in the degree of swallowing function preservation in two groups of irradiated NPC patients: the conventional RT and the IMRT group.
Thirty patients with NPC who received RT from 1998 to 2006 in Queen Mary Hospital, Hong Kong were randomly recruited during the period from January to December 2011. Participant’s swallowing competence and its effect on the quality of life was assessed by videofluoroscopic swallowing study (VFSS) and by the MD Anderson Dysphagia Inventory, respectively.
In comparison of swallowing performance with VFSS between the two groups, only one measure (Duration of Laryngeal Elevation) out of 13 showed significant difference on thin liquid and congee diet. Results from the MDADI did not show significant difference between the two groups.
From the results, it was concluded that IMRT only resulted in subtle improvement in preserving the swallowing function as compared to conventional RT. One possibility is the subject self-compensation of their swallowing impairments that led to functionally similar performance despite their differences in the anatomy and physiology. Swallowing is a highly complex body function and no single parameter can be used to accurately quantify and characterize one’s swallowing function. The interaction between the anatomical and physiological impairments resulted from radiation therapy and the compensatory mechanism could not be clearly explained with this study. Future research could adopt a longitudinal approach such that the changes in NPC patients who received radiation therapy can be better understood.published_or_final_version
Speech and Hearing Sciences
Master
Master of Philosophy
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Martínez, Rovira Immaculada. "Monte Carlo and experimental small-field dosimetry applied to spatially fractionated synchrotron radiotherapy techniques." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/81470.
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Two innovative radiotherapy (RT) approaches are under development at the ID17 Biomedical
Beamline of the European Synchrotron Radiation Facility (ESRF): microbeam radiation
therapy (MRT) and minibeam radiation therapy (MBRT). The two main distinct characteristics
with respect to conventional RT are the use of submillimetric field sizes and spatial
fractionation of the dose. This PhD work deals with different features related to small-field
dosimetry involved in these techniques. Monte Carlo (MC) calculations and several experimental
methods are used with this aim in mind. The core of this PhD Thesis consisted of the
development and benchmarking of an MC-based computation engine for a treatment planning
system devoted to MRT within the framework of the preparation of forthcoming MRT
clinical trials. Additional achievements were the definition of safe MRT irradiation protocols,
the assessment of scatter factors in MRT, the further improvement of the MRT therapeutic
index by injecting a contrast agent into the tumour and the definition of a dosimetry protocol
for preclinical trials in MBRT.
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Newbold, Katie Lindsay. "The application of advanced imaging techniques to radiotherapy planning in head and neck cancer." Thesis, Institute of Cancer Research (University Of London), 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498512.
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Walton, Dean R. "Effect of slit scan imaging techniques on image quality on radiotherapy electronic portal imaging." Connect to full text in OhioLINK ETD Center, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=mco1217886133.
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Thesis (M.S.)--University of Toledo, 2008."In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Title from title page of PDF document. Bibliography: pages 67-72.
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Ahmed, Saeed. "Development and Validation of Advanced Techniques for Treatment Planning and Verification in Megavoltage Radiotherapy." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7721.
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The aim of this work is primarily to validate the advanced techniques for treatment planning and dosimetric verification for modern megavoltage x-ray radiotherapy. With the advent of modern radiotherapy techniques, there is a great need for assuring quality of the radiation dose distributions generated by the advanced intensity modulated treatments (IMRT/VMAT). This is typically accomplished by the assessment of the treatment plan quality at the planning stage and then verification of the dose distributions through measurements on the phantoms or independent dose calculations prior to the actual delivery of these plans to patients. The major focus of this work is to clinically evaluate the modern 2D and 3D dose verification techniques.
The measurement-based dosimetry systems investigated were ArcCHECK/3DVH and SRS MapCHECK. AcrCHECK/3DVH system uses the measurement-guided dose reconstruction algorithm to correct the predicted dose in the patient dataset. The system was intended for VMAT/IMRT QA. SRS MapCHECK was investigated for SRS treatments. The independent dose calculation system was DoseCHECK which employed a GPU-accelerated convolution-superposition of algorithm for 3D dose reconstruction on the patient dataset. Next, a hybrid dose verification system (PerFRACTION) was evaluated, which takes input from both the treatment planning system and the linac EPID and produces a measurement-guided 3D dose distribution for comparison with the plan. This system was investigated for potential QA applications to a modern, efficient SRS technique, involving simultaneously treating multiple targets with a single isocenter. The performance of all dosimetry systems was validated against well-characterized independent dosimeters, such as ion chamber, film and scintillator detectors, or 3D arrays (Delta4), using stringent dose comparison criteria to test their limits for the intended clinical applications.
For the initial plan quality evaluation of a novel tool (Feasibility DVH) was investigated. This tool a priori estimates best achievable dose volume histograms for a specific patient, based on the basic physics properties of the megavoltage x-rays, thus helping the planners to guide their efforts.
All studied dosimetry systems showed an excellent agreement of the average gamma (a mathematical combination of DD and DTA) passing rates >98% for most of the plans. The 3% DD/2mm DTA criteria were used for extracranial plans and 3%/1mm for intracranial SRS plans. As dictated by the logic of the application, the comparisons were made against TPS calculations, a bi-planar array, or film measurements. Similarly the average percent point dose errors <2% were observed against the ion chambers or film. In the rare instances when the deviations were larger, intuitive explanations were provided, based on either the physics of the plans or inhomogeneous patient anatomy and resulting algorithm limitations.
Feasibility DVH was shown to reliably predict the best possible organ sparing for clinical head-and-neck VMAT plans.
Overall the investigated dosimetry systems were found reliable and feasible for their intended clinical use.
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Christian, Judith Ann. "Evaluation of new techniques in the radiotherapy treatment of non-small cell lung cancer." Thesis, Institute of Cancer Research (University Of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411594.
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De, La Fuente Herman Tania. "The impact of dosimetric optimization using respiratory gating and inhomogeneity corrections on potential therapeutic gain in patients with lung cancer a dissertation /." San Antonio : UTHSC, 2008. http://proquest.umi.com/pqdweb?did=1633773551&sid=3&Fmt=2&clientId=70986&RQT=309&VName=PQD.
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Carr, Simon David. "Assessing the effects of radiotherapy on head and neck squamous cell carcinoma using microfluidic techniques." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:8396.
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Objective The aim of this study was to investigate how HNSCC tissue biopsies maintained in a pseudo in vivo environment within a bespoke microfluidic device, respond to radiation treatment. Materials and Methods 35 patients with HNSCC were recruited; in addition liver tissue from 5 Wistar rats was used. A glass microfluidic device was used to maintain the tissue biopsy samples in a viable state. Rat liver was used to optimise the methodology. HNSCC was obtained from patients with T1-T3 laryngeal or oropharyngeal SCC; N1-N2 metastatic cervical lymph nodes were also obtained. Irradiation consisted of single doses of between 2 Gy and 40 Gy and a fractionated course of 5x2 Gy. Cell death was assessed in the tissue effluent using the soluble markers LDH and cytochrome c, and in the tissue by immunohistochemical detection of cleaved cytokeratin18 (M30 antibody). Radiation-induced DNA strand breaks were detected using the TUNEL assay. Results A significant surge in LDH release was demonstrated in the rat liver after a single dose of 20 Gy; in HNSCC it was seen after 40 Gy, compared to the control. There was no significant difference in cytochrome c release after 5 Gy or 10 Gy. M30 demonstrated a dose-dependent increase in apoptotic index for a given increase in single dose radiation. There was a significant increase in apoptotic index between the non-irradiated HNSCC tissue and irradiated tissue and between the tissue irradiated with 1x2 Gy and 5x2 Gy. As with the apoptotic index, there was a significant increase in radiation-induced DNA breaks between the non-irradiated and the irradiated tissue and between the tissue irradiated with 1x2 Gy and 5x2 Gy. Conclusion This microfluidic technique can be used to study the effects of radiation on HNSCC tissue. The device was capable of maintaining the HNSCC in a viable state, without it undergoing significant apoptosis or DNA damage and can be used to demonstrate the relationship between radiotherapy dose and radiation-induced cell death using tissue-based cell death markers. This study is a significant step towards achieving the ultimate goal of developing this device as a tool, capable of predicting a patient’s response to radiotherapy prior to the commencement of treatment.
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Wu, Wing-cheung Vincent. "Dose analysis of 2-dimensional and 3-dimensional radiotherapy techniques in the treatment of nasopharyngeal carcinoma /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19625492.
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Whittington, Lesley Susan. "An investigation of healing and tissue changes in plantar skin resulting from two surgical techniques : radiofrequency electrodesiccation and curettage." Thesis, University of Kent, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589931.
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McKenna, Frederick W. "Studies of cell survival curve fitting, effective doses for radiobiological evaluation in SBRT treatment techniques and the dependence of optical density growth in Gafchromic EBT film used in IMRT." Oklahoma City : [s.n.], 2009.
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CECILIO, PAULO J. "Implementacao e aceite de sistema de radioterapia de feixe modulado dinamico com o uso de colimador secundario de multiplas folhas." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11757.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Heikkilä, V. P. (Vesa-Pekka). "New techniques and methods for decreasing healthy tissue dose in prostate cancer radiotherapy, with special reference to rectal doses." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526212081.
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Abstract Prostate cancer is the most common cancer among men in Western industrialized countries. Approximately 60% of prostate cancer patients receive radiotherapy at some phase of the disease, a treatment based on the use of ionizing radiation to kill or control malignant cells. Unfortunately, adjoining healthy tissues are also affected by exposure to ionization, potentially leading to the emergence of adverse side effects, even several years later. The main radiation treatment modalities are external radiotherapy and low dose rate (LDR) or high dose rate (HDR) brachytherapy. Different techniques and methods are used to decrease the dose to healthy tissues, thus limiting the possibility of adverse effects. In this thesis a novel technique and associated equipment were developed whereby brachytherapy can be performed by inserting all needles simultaneously. This reduces the implantation time, thus minimizing the impairing effect on seed positioning accuracy resulting from prostate swelling. A phantom model was also constructed for testing and training purposes. DuraSeal® was investigated as a spacer material between the prostate and rectum, and its effect on rectal dose was evaluated during brachytherapy and external radiotherapy. DuraSeal® is resorbed over one to six months, thus altering rectal doses compared with the original dose plan. In brachytherapy, the resorption effect on rectal doses was calculated along with an evaluation of the potential of using different isotopes. In external radiotherapy, the resorption effect on rectal dose-volume histograms (DVHs) was calculated and the need for adaptive planning considered. DuraSeal®, as a spacer gel, clearly has favorable effects on rectal and anterior rectal wall DVHs in brachytherapy and external radiotherapy, and has the potential to decrease adverse effects. It is especially beneficial in hypofractionated treatments and external radiotherapy and brachytherapy combination treatment. In LDR brachytherapy using permanent seeds, dose planning is recommended prior to gel injection to prevent excessive rectal tolerance doses in situations where gel is rapidly resorbed. In external radiotherapy, the use of adaptive planning with a spacer gel improves rectal DVH, but is not necessary according to this thesisTiivistelmä Eturauhasen syöpä on läntisten teollistuneiden maiden miesten yleisin syöpä. Arviolta 60 % eturauhassyöpäpotilaista saa sairauden jossain vaiheessa sädehoitoa. Sädehoito perustuu syöpäsolujen kontrolloimiseen ja tuhoamiseen ionisoivalla säteilyllä. Valitettavasti ionisoiva säteily vaikuttaa myös ympäröivään tervekudokseen aiheuttaen mahdollisia haittavaikutuksia jopa vuosien päästä. Sädehoidon kolme päätyyppiä ovat ulkoinen sädehoito sekä matala- ja korkea-annosnopeuksinen tykösädehoito (brakyterapia). Tervekudosannosten pienentämiseksi ja siten myös mahdollisten haittavaikutusten vähentämiseksi käytetään eri menetelmiä ja tekniikoita. Tässä väitöskirjassa kehitettiin uusi menetelmä ja laitteisto, joiden avulla voidaan brakyterapiassa asettaa kaikki neulat samanaikaisesti eturauhaseen. Menetelmä nopeuttaa implantointivaihetta, jolloin eturauhasen turpoaminen ei ehdi vaikuttaa jyvien asettelutarkkuutta heikentävästi. Samassa yhteydessä rakennettiin myös fantomi laadunvalvontaa ja harjoittelua varten. Työssä tutkittiin ja arvioitiin myös DuraSeal® geelin käyttöä välikemateriaalina eturauhasen ja peräsuolen välissä sekä geelin vaikutusta peräsuoliannoksiin. DuraSeal® resorboituu kuuden kuukauden aikana muuttaen alkuperäisen annossuunnitelman mukaista peräsuoliannosta. Brakyterapiassa tutkittiin ja laskettiin resorption vaikutusta sekä arvioitiin eri isotooppien käyttöä. Ulkoisessa sädehoidossa laskettiin resorption vaikutusta peräsuolen tilavuushistogrammeihin ja tutkittiin mahdollisen adaptiivisen suunnittelun käyttöä. DuraSeal® geelin käyttö välikemateriaalina pienentää selkeästi peräsuoliannoksia ja siten myös mahdollisesti tervekudosten haittavaikutuksia sekä ulkoisessa sädehoidossa että brakyterapiassa. Geelin käyttö on erityisen hyödyllistä hypofraktiohoidoissa sekä ulkoisen sädehoidon ja brakyterapian kombinoidussa käytössä. Matala-annosnopeuksisessa brakyterapiassa (jyvähoidoissa) annossuunnitelma suositellaan tehtäväksi ennen geelin ruiskutusta, jotta peräsuolen toleranssiannoksia ei ylitettäisi vaikka geeli resorboituisikin nopeasti. Ulkoisessa sädehoidossa adaptiivinen suunnittelu välikegeelin kanssa tuo lisäarvoa pienentämällä edelleen peräsuoliannoksia, mutta ei ole välttämätöntä
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CARVALHO, GUILHERME L. de C. "Estudo de análogo da substância P para desenvolvimento de radiofármaco com aplicação na terapia de tumores cerebrais." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/24067.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-10-28T11:15:14Z
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Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Jarry, Geneviève. "Study of novel techniques for verification imaging and patient dose reconstruction in external beam radiation therapy." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103025.
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Treatment delivery verification is an essential step of radiotherapy. The purpose of this thesis is to develop new methods to improve the verification of photon and electron beam radiotherapy treatments. This is achieved through developing and testing (1) a way to acquire portal images during electron beam treatments, (2) a method to reconstruct the dose delivered to patients during photon beam treatments and (3) a technique to improve image quality in kilovoltage (kV) cone beam computed tomography (CBCT) by correcting for scattered radiation. The portal images were acquired using the Varian CL21EX linac and the Varian aS500 electronic portal imaging device (EPID). The EGSnrc code was used to model fully the CL21EX, the aS500 and the kV CBCT system.We demonstrate that portal images of electron beam treatments with adequate contrast and resolution can be produced using the bremsstrahlung photons portion of the electron beam. Monte Carlo (MC) calculations were used to characterize the bremsstrahlung photons and to obtain predicted images of various phantoms. The technique was applied on a head and neck patient.
An algorithm to reconstruct the dose given to patients during photon beam radiotherapy was developed and validated. The algorithm uses portal images and MC simulations. The primary fluence at the detector is back-projected through the patient. CT geometry to obtain a reconstructed phase space file. The reconstructed phase space file is used to calculate the reconstructed dose to the patient using MC simulations. The reconstruction method was validated in homogeneous and heterogeneous phantoms for conventional and IMRT fields.
The scattered radiation present in kV CBCT images was evaluated using MC simulations. Simulated predictions of the scatter distribution were subtracted from CBCT projection images prior to the reconstruction to improve the reconstructed image quality. Reducing the scattered radiation was found to improve contrast and reduce shading artifacts.
MC simulations, in combination with experimental techniques, have been shown to be valuable tools in the development of treatment verification methods. The three novel methods presented in this thesis contribute to the improvement of radiotherapy treatment verification. They can potentially improve treatment outcome by ensuring a better target coverage.
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Wake, Giulia M. G. H. "Exact minimisation of treatment time for the delivery of intensity modulated radiation therapy." University of Western Australia. School of Mathematics and Statistics, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0195.
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This thesis investigates the exact minimisation of treatment delivery time for Intensity Modulated Radiation Therapy (IMRT) for the treatment of cancer using Multileaf Collimators (MLC). Although patients are required to remain stationary during the delivery of IMRT, inevitably some patient movement will occur, particularly if treatment times are longer than necessary. Therefore minimising the treatment delivery time of IMRT may result in less patient movement, less inaccuracy in the dosage received and a potentially improved outcome for the patient. When IMRT is delivered using multileaf collimators in 'step and shoot' mode, it consists of a sequence of multileaf collimator configurations, or shape matrices; for each, time is needed to set up the configuration, and in addition the patient is exposed to radiation for a specified time, or beam-on time. The 'step and shoot leaf sequencing' problems for minimising treatment time considered in this thesis are the constant set-up time Total Treatment Time (TTT) problem and the Beam-on Time Constrained Minimum Cardinality (BTCMC) problem. The TTT problem minimises a weighted sum of total beam-on time and total number of shape matrices used, whereas the BTCMC problem lexicographically minimises the total beam-on time then the number of shape matrices used in a solution. The vast majority of approaches to these strongly NP-hard problems are heuristics; of the few exact approaches, the formulations either have excessive computation times or their solution methods do not easily incorporate multileaf collimator mechanical constraints (which are present in most currently used MLC systems). In this thesis, new exact mixed integer and integer programming formulations for solving the TTT and BTCMC problems are developed. The models and solution methods considered can be applied to the unconstrained and constrained versions of the problems, where 'constrained' refers to the modelling of additional MLC mechanical constraints. Within the context of integer programming formulations, new and existing methods for improving the computational efficiency of the models presented are investigated. Numerical results for all variations considered are provided. This thesis demonstrates that significant computational improvement can be achieved for the exact mixed integer and integer programming models investigated, via solution approaches based on an idea of systematically 'stepping-up' through the number of shape matrices used in a formulation, via additional constraints (particularly symmetry breaking constraints) and via the application of improved bounds on variables. This thesis also makes a contribution to the wider field of integer programming through the examination of an interesting substructure of an exact integer programming model. In summary, this thesis presents a thorough analysis of possible integer programming models for the strongly NP-hard 'step and shoot' leaf sequencing problems and investigates and applies methods for improving the computational efficiency of such formulations. In this way, this thesis contributes to the field of leaf sequencing for the application of Intensity Modulated Radiation Therapy using Multileaf Collimators.
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Cecilio, Paulo José. "Implementação e aceite de sistema de radioterapia de feixe modulado dinâmico com o uso de colimador secundário de múltiplas folhas." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-03052012-094138/.
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A radioterapia de feixe de intensidade modulada (IMRT) no seu modo dinâmico é uma forma de radioterapia tri-dimensional (3D), na qual modula-se um feixe de forma a obter-se a irradiação com campos que possuem perfil variável. Os campos são gerados por um sistema de otimização matemático e transformado em seqüências de movimento ou abertura de lâminas dos colimadores terciários de múltiplas folhas (MLC) ou feixe colimado helicoidal, reproduzindo a fluência de radiação adequada. No processo o operador atribui valores limitantes de dose ao alvo e aos órgãos de risco circunvizinhos para que o sistema de planejamento inverso realize a otimização possível. Após a aprovação do plano de tratamento o mesmo deve ser conferido, através de um controle de qualidade (CQ), onde são verificadas as doses que deverão ser administradas ao paciente, comprovando-se as doses obtidas e aprovadas no plano do sistema de planejamento (SPC). Para este controle os mesmos feixes e campos são medidos em termos de dose absorvida e perfis, através de dosimetria na qual comprova-se que não há erro físico ou dosimétrico no plano que irá tratar o paciente com diferença aceitável de até 5%, também utilizada como tolerância para a aprovação dos 460 casos avaliados nesta tese. Foram apresentados as metodologias para a aceitação no primeiro serviço a utilizá-la no Brasil e os testes de controle de qualidade de dois serviços de radioterapia, desde agosto de 2001 à maio de 2006 e no outro serviço de outubro de 2007 a maio de 2008, com controle de qualidade que permitiram os respectivos tratamentos clínicos com dados de 4 anos, ou seja, 460 casos com 3935 campos de tratamento verificados individualmente por dosimetria. Isto possibilitou o aperfeiçoamento da metodologia e garantia da qualidade nos tratamentos de IMRT dinâmico destes pacientes.The intensity modulated radiation therapy (IMRT) is a type of radiation therapy using dynamic sliding window which modulated the beamlets of each field which are thus obtained as a variable profile. The multiple fields are obtained by mathematic optimization in special treatment planning system. In this way, the resulted field is generated by leaf sequencing using the multi-leaf collimator (MLC) or helicoidally beam. The optimization is an interactive process with operator and planning system where the dose prescription to target and dose limit for organ of risk are inserted to obtain the acceptable beam fluence and this process is named as inverse planning. The planning approved by physician should checked by means of dosimetry in order to assure the correct dose delivery; this action is the main task of a quality control (QC) program. The QC is performed by measurements of total absorbed dose and profile for each field planned for the patient. The acceptance level is 5% for total dose and was used for all 460 cases and 3935 fields analyzed between August 2001 to May 2006 at Albert Einstein Hospital and October 2007 to May 2008 at the Centro Infantil Dr. Boldrini. This work performs an analysis of the QC of treatments plans for all patients treated with IMRT. During four years the methodologies were frequently improved and upgradated for each tumor site and could thus be assured for the required quality of all treatments with dynamic IMRT.
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Raymond, Christophe. "Radio-imageurs a fibres optiques plastiques scintillantes." Paris 7, 1987. http://www.theses.fr/1987PA077152.
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Jones, Bernard Lee. "Development of dosimetry and imaging techniques for pre-clinical studies of gold nanoparticle-aided radiation therapy." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43727.
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Cancer is one of the leading causes of death worldwide, and affects roughly 1.5 million new people in the United States every year. One of the leading tools in the detection and treatment of cancer is radiation. Tumors can be detected and identified using CT or PET scans, and can then be treated with external beam radiotherapy or brachytherapy. By taking advantage of the physical properties of gold and the biological properties of nanoparticles, gold nanoparticles (GNPs) can be used to improve both cancer radiotherapy and imaging. By infusing a tumor with GNPs, either using passive extravasation of nanoparticles by the tumor vasculature or active targeting of an antibody-conjugated nanoparticle to a specific tumor marker, the higher photon cross-section of gold will cause more radiation dose to be deposited in the tumor during photon-based radiotherapy. In principle, this would allow escalation of dose to the tumor while not increasing the dose to normal healthy tissue. Additionally, if a tumor infused with GNPs was irradiated by an external kilo-voltage source, the fluorescence emitted by the gold atoms would allow one to localize and quantify the GNP concentration. This work has two main aims: to quantify the GNP-mediated dose enhancement during GNRT on a nanometer scale, and to develop a refined imaging modality capable of quantifying GNP location and concentration within a small-animal-sized object. In order to quantify the GNP-mediated dose enhancement on a nanometer scale, a computational model was developed. This model combines both large-scale and small-scale calculations in order to accurately determine the heterogeneous dose distribution of GNPs. The secondary electron spectra were calculated using condensed history Monte Carlo, which is able to accurately take into account changes in beam quality throughout the tumor and calculate the average energy spectrum of the secondary charged particles created. Then, the dose distributions of these electron spectra were calculated on a nanometer scale using event-by-event Monte Carlo. The second aim is to develop an imaging system capable of reconstructing a tomographic image of GNP location and concentration in a small animal-sized object by capturing gold fluorescence photons emitted during irradiation of the object by an external beam. This would not only allow for localization of GNPs during gold nanoparticle-aided radiation therapy (GNRT), but also facilitate the use of GNPs as imaging agents for drug-delivery or other similar studies. The purpose of this study is to develop a cone-beam implementation of XFCT that meets realistic constrains on image resolution, detection limit, scan time, and dose. A Monte Carlo model of this imaging geometry was developed and used to test the methods of data acquisition and image reconstruction. The results of this study were then used to drive the production of a functioning benchtop, polychromatic cone-beam XFCT system.
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Colnot, Julie. "Risques de complications associés à la radiothérapie externe : étude comparative des doses délivrées aux tissus sains par les techniques avancées de radiothérapie." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS299/document.
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Les techniques modernes de radiothérapie externe permettent de délivrer précisément la dose à la tumeur. Ce gain en précision se fait cependant au prix de l’irradiation d’un volume plus important de tissus sains alors susceptibles de développer des lésions radio-induites. Aujourd’hui, les risques de complications représentent un enjeu sociétal important, car l’efficacité des traitements permet aux patients une espérance de vie plus longue, augmentant ainsi la probabilité d’effets secondaires à moyen et à long terme. Cependant, l’estimation des risques est conditionnée par une connaissance précise des doses délivrées aux organes sains, directement corrélées aux risques de complications. Ces doses restent encore méconnues, car renseignées de manière incomplète et imprécise par les systèmes de planification de traitement (TPS). Dans ce contexte, l’objectif de la thèse est d’évaluer avec précision les doses délivrées aux tissus sains par les techniques avancées de radiothérapie. D’une part, une étude comparative des doses délivrées aux tissus sains par différentes techniques avancées a été réalisée et, d’autre part, les performances, en termes d’évaluation des doses aux tissus sains des algorithmes des TPS ont été évaluées. Des méthodes numériques et expérimentales ont donc été développées. Tout d’abord, un modèle Monte-Carlo PENELOPE de l’accélérateur Cyberknife a été étendu et validé en 1D et 2D pour l’évaluation des doses hors champ. Ce modèle a ensuite été utilisé pour déterminer les doses délivrées aux tissus sains lors d’un traitement de la région pulmonaire. Cette étude a ainsi permis de fournir des données d’entrée pour les modèles de risque et enfin, de mettre en évidence l’apport en précision de la simulation Monte-Carlo détaillée par rapport au TPS. De plus, un outil expérimental de reconstruction de la dose en 3D à partir de mesures par films radiochromiques a été développé. Un protocole de dosimétrie par gel dosimétrique a également été mis en place. Après validation en 2D et en 3D, l’outil de reconstruction a été mis en œuvre pour comparer les doses délivrées aux tissus sains par trois techniques de radiothérapie (conformationnelle, VMAT et tomothérapie) pour un traitement rénal pédiatrique. Bien que les techniques avancées offrent une excellente conformation, les tissus sains reçoivent des doses jusqu’à 3 fois plus élevées en comparaison avec la radiothérapie conformationnelle. La tomothérapie, disposant d’un blindage supplémentaire, épargne mieux les tissus que le VMAT. Finalement, contrairement à Eclipse™, le TPS de la tomothérapie détermine précisément des doses délivrées jusqu’à 30 cm du champAdvanced radiotherapy techniques enable highly conformal dose distribution to the tumor. This higher precision is made at the cost of an increased tissue volume receiving low doses. The exposed organs are then susceptible to develop radio-induced lesions. Nowadays, risks of complications represent an important societal challenge as survival rates are increasing due to treatment efficacy and therefore the risk for a subsequent effect also increases. However, risk assessment requires a precise knowledge of the doses delivered to healthy organs, directly correlated to the risk of complications. Those doses are still unknown as calculated incorrectly by the treatment planning systems (TPS). Within this context, this thesis aims at precisely determining the doses delivered to normal tissues by advanced radiotherapy techniques. On the one hand, a comparative study of the doses delivered by different modern techniques was performed and on the other hand, the performance of the TPS dose computation algorithms was evaluated in terms of healthy tissue doses. Thus, numerical and experimental tools have been developed in this work. First, a PENELOPE Monte-Carlo model of a CyberKnife system has been extended and validated in 1-D and 2-D to determine out-of-field doses. This model was then used to evaluate the doses delivered to healthy tissue by a pulmonary treatment. This study provides requisite dosimetric data to evaluate the risks associated to the treatment and finally, it highlights the important precision of detailed Monte-Carlo simulation in comparison with the TPS. Moreover, an experimental 3-D reconstruction tool was developed thanks to radiochromic film measurements. A protocol of gel dosimetry was also established. After 2-D and 3-D validation, the 3-D tool was applied to compare the doses delivered by three radiotherapy techniques (conformational, VMAT and tomotherapy) in a pediatric renal treatment. While advanced techniques deliver highly conformal dose distribution, the doses to organs located at distance of the target are considerably increased up to a factor 3 in comparison with conformal radiotherapy. The tomotherapy spares the healthy tissues compared to VMAT due to its additional shielding. Finally, unlike Eclipse™, the TPS Tomotherapy enables a precise dose evaluation up to 30 cm from the field edge
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Yang, Ming Chao. "Optimisation des plans de traitement en radiothérapie grâce aux dernières techniques de calcul de dose rapide." Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-01011223.
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Cette thèse s'inscrit dans la perspective des traitements de radiothérapie en insistant sur la nécessité de disposer d'un logiciel de planification de traitement (TPS) rapide et fiable. Le TPS est composé d'un algorithme de calcul de dose et d'une méthode d'optimisation. L'objectif est de planifier le traitement afin de délivrer la dose à la tumeur tout en sauvegardant les tissus sains et sensibles environnant. La planification des traitements consiste à déterminer les paramètres d'irradiation les mieux adaptés au patient. Dans le cadre de cette thèse, les paramètres d'un traitement par RCMI (Radiothérapie Conformationnelle avec Modulation d'Intensité) sont la position de la source, les orientations des faisceaux et, pour chaque faisceau composé de faisceaux élémentaires, la fluence de ces derniers. La fonction objectif est multicritère en associant des contraintes linéaires. L'objectif de la thèse est de démontrer la faisabilité d'une méthode d'optimisation du plan de traitement fondée sur la technique de calcul de dose rapide développée par (Blanpain, 2009). Cette technique s'appuie sur un fantôme segmenté en mailles homogènes. Le calcul de dose s'effectue en deux étapes. La première étape concerne les mailles : les projections et pondérations y sont paramétrées en fonction de critères physiques et géométriques. La seconde étape concerne les voxels: la dose y est calculée en évaluant les fonctions préalablement associées à leur maille.Une reformulation de cette technique permet d'aborder le problème d'optimisation par la méthode de descente de gradient. L'optimisation en continu des paramètres du traitement devient envisageable. Les résultats obtenus dans le cadre de cette thèse ouvrent de nombreuses perspectives dans le domaine de l'optimisation des plans de traitement en radiothérapie.
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LIMA, JOSE R. de. "Projeto e desenvolvimento de um dispositivo automático de controle e alimentação de tubos de titânio e fios de prata para a produção de sementes de Iodo - 125." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26944.
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Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2016-12-22T13:06:17Z
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No Brasil, o câncer de próstata é um dos tipos de câncer que mais afeta a população masculina, sendo o segundo mais incidente, ficando atrás apenas do câncer de pele não melanoma que é o mais ocorrente na população. Existem vários procedimentos para o tratamento do câncer de próstata, dentre eles temos a braquiterapia com sementes de Iodo- 125, este método é realizado inserindo sementes com Iodo radioativo na próstata do paciente. As sementes são constituídas de uma capsula de titânio medindo 0,8 mm de diâmetro por 4,5 mm de comprimento com um fio de prata medindo 0,5 mm de diâmetro por 3,0 mm de comprimento, adsorvido com Iodo-125, que é selado por meio de solda laser. As tecnologias usadas nos processos de produção de sementes de Iodo-125 são protegidas por patentes e a obtenção dos direitos de produção apresenta um custo elevado, inviabilizando a sua produção por esses processos devidos aos custos. O objetivo deste trabalho é desenvolver o projeto de um dispositivo para a contagem dos tubos de titânio e dos fios de prata usados na confecção das sementes de Iodo-125, este objetivo foi atingido estabelecendo uma metodologia para o posicionamento dos fios de prata e sua condução para o processo de contagem. Para tanto, foi projetado, construído e utilizado um novo dispositivo que se encontra hoje totalmente operacional. Foram utilizados motores de passo e sensores óticos para auxiliar no processo de automação do conjunto.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Silva, Hugo Leonardo Lemos. "Caracterização e dosimetria de feixes de raios-x de 100 e 140kVp usados em radioterapia." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2006. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=59.
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Radioterapia é a modalidade de tratamento, principalmente de neoplasias malignas, cuja finalidade é a deposição de uma quantidade controlada de radiação ionizante numa região limitada do corpo do paciente.
Para que a dose de controle da lesão seja ministrada com a maior exatidão o possível, deve-se conhecer todos as características do feixe de radiação utilizado no tratamento. Dessa forma, foram desenvolvidos protocolos de calibração, para feixes de radiacão ionizante, que estabelecem
as regras que, quando seguidas adequadamente, conduzirão ao conhecimento do feixe de radiação no seu aspecto clínico e dosimétrico.
O presente trabalho faz uma análise dos parâmetros de caracterização e dosimetria de feixes de raios-x superficiais de 100 e 140 kVp utilizados em radioterapia, através do AAPM protocol for 40-300 kV x-ray beam dosimetry in radiotherapy and radiobiology, cujos os parâmetros dosimétricos relatados para terapia superficial são os mais atuais existentes. Tal análise forneceu um guia de calibração para físicos e médicos que pretendem disponibilizar feixes de raios-x terapêuticos de 40 a 300 kVp em hospitais e se restringiu à metodologia de calibração do feixe no ar livre, onde foram determinados e analisados, parâmetros de caracterização como:
camada semi-redutora, coeficiente de homogeneidade, distribuição espectral do feixe, energia máxima e média do feixe, tempo de estabilização e parâmetros dosimétricos como: fator de retroespalhamento, fator de calibração, linearidade da dose absorvida e coeficiente de absorção de energia mássico médio água-ar, no ar livre, além dos fatores de correção da leitura obtida com a câmara de ionização.
A análise das incertezas associadas aos parâmetros de caracterização e dosimetria, permitiu estabelecer quais parâmetros contribuem de forma mais significativa no aumento da incerteza expandida associada à taxa de dose absorvida na superfície da água; e portanto, sua determinação deve ser metrologicamente melhorada.Radiotherapy is the modality used in the treatment of malignant neoplasias that aims the deposition of a controlled amount of ionizing radiation in a limited area of the patient body. In order to provide a well-known and as accurate as possible absorbed dose for controlling a lesion, all characteristics of the treatment radiation beam must be known. For this purpose, protocols were developed and used for calibrating those beams; they are a set of rules and procedures that are to be followed appropriately to achieve the knowledge of the clinical and dosimetric aspects of the radiation beam. This work carries out the measurement and analysis of parameters aiming the characterization and dosimetry of a 100 and a 140 kVp superficial x-ray beams to be used for radiotherapy; the AAPM protocol for 40-300 kV x-ray beam dosimetry in radiotherapy and radiobiology was used for such purpose. Characterization parameters as half-value layer, homogeneity coefficients, spectral beam distribution, maximum and minimum radiation energy, time stabilization and dosimetric parameters as backscatter factor, calibration factor, linearity of the absorbed dose in air, free-in air, air to water ratios of the mass energy-absorption coefficients, besides ionization chamber corrections factors were determined and analyzed. The analysis of the uncertainty components concerned to the beam characterization and dosimetry was done and it allowed to identify which one is more significant and it needs to be improved to reduce the expanded uncertainty in the absorbed dose rate on the water surface. By adopting the free-in-airmethodology, a calibration guideis offered to physicists and doctors who intend to apply therapeutic soft x-ray beams from 40 to 300 kVp in hospitals.
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Nassef, Mohamed. "Monitoring de dose pour la radiothérapie du cancer de la prostate." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S033/document.
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Cette thèse porte sur la prise en compte des variations anatomiques, notamment les déformations d’organes à risque (rectum, vessie), pouvant survenir lors du traitement de radiothérapie conformationnelle par modulation d’intensité du cancer de la prostate. Ces variations peuvent entrainer d’importants écarts dosimétriques par rapport au plan de traitement initialement optimisé, et augmenter le risque de complications. Grâce à l’évolution des dispositifs d’imagerie et des méthodes de traitement d’images, des approches permettant de cumuler la dose au cours du traitement ont été récemment proposées mais restent mal évaluées et leur intégration dans un schéma de radiothérapie adaptative suscite de nombreuses questions. Ainsi, la première partie de ce travail a consisté à évaluer, à l’aide d’un fantôme numérique, une méthode de suivi de dose développée récemment au LTSI. Les résultats obtenus ont montré que les incertitudes dosimétriques liées à l’algorithme de cumul de dose sont limitées par rapport aux dérives dosimétriques observées chez les patients. La seconde partie de ce travail a consisté à proposer une stratégie de radiothérapie adaptative reposant sur le suivi de dose et à évaluer son bénéfice dosimétrique sur trois patients pour lesquels des dérives avaient été observées. Le principe de cette méthode est de détecter les dérives dosimétriques entre la dose planifiée et la dose réellement délivrée et, si besoin, de les compenser grâce à une ou plusieurs replanifications. Les résultats obtenus ont montré que cette approche permet une réduction de la dérive aux organes à risque, tout en augmentant la dose au volume cible en comparaison à un traitement standard par IGRT, avec un nombre limité de replanifications (une ou deux) permettant d’envisager une implémentation cliniqueThis thesis concerns the compensation of the anatomical variations, mainly the organs at risk (rectum, bladder) deformations, which occur during intensity modulated radiotherapy of the prostate cancer. These variations can lead to significant dose drift compared to the initially planned dose, increasing the risk of toxicity. Thanks to the evolution of imaging devices and of image processing methods, dose accumulation processes, allowing to estimate the cumulated dose during the treatment, have been recently proposed. Nevertheless those strategies suffer of a lack of evaluation and their integration into an adaptive radiotherapy raises many questions. Thus, in the first part of this work, a dose accumulation method recently developed at the LTSI was evaluated using a numerical phantom. The results obtained showed that the dosimetric uncertainties related to the cumulated dose process remain low compared to the dose drifts observed for patients. The second part of this work aimed to develop a dose guided adaptive radiotherapy process and to evaluate its dosimetrical benefit using three patients showing a dose drift. The principle of this method is to detect a potential drift between the planned and actually delivered doses and, if necessary, to compensate them thanks to one or more replanning(s). The results have shown that this approach has reduced the dose drift to the organs at risk, while increasing the dose to the prostate compared to standard IGRT treatment, with a limited number of replannings (one or two), enabling to consider a clinical implementation
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Denissova, Svetlana. "A gated breath-hold radiotherapy technique using a linear position transducer." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19417.
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For patients with thoracic and abdominal lesions, respiration-induced internal organ motion and deformations during radiation therapy are limiting factors for the administration of high radiation dose. In order to escalate the dose to the tumor and reduce the treatment margins, the tumor movement during treatment must be minimized. In our approach we have established a largely automated deep-breath-hold technique for treating lung cancer patients. We have used a Linear Position Transducer to monitor tumor movement through changes in the patient's abdominal cross-sectional area. The technique aims to reduce the amount of healthy lung tissue in high-dose regions. Normal tissue can be spared as a result of two distinct features of this method: deep inspiration, which reduces the lung density, and breath hold, which immobilizes the tumor. Due to reduced tumor motion, the Planning Target Volume margins can be tightened and a higher dose of radiation can be delivered to the tumor with the same risk of normal tissue complications.
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Trullo, Ramirez Roger. "Approche basées sur l'apprentissage en profondeur pour la segmentation des organes à risques dans les tomodensitométries thoraciques." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR063.
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La radiothérapie est un traitement de choix pour le cancer thoracique, l’une des principales causes de décès dans le monde. La planification de la radiothérapie nécessite de contourer non seulement la tumeur, mais également les organes à risque (OAR) situés près de la tumeur dans le thorax, tels que le coeur, les poumons, l’oesophage, etc. Cette segmentation permet de minimiser la quantité d’irradiation reçue pendant le traitement. Aujourd’hui, la segmentation de OAR est réalisée principalement manuellement par des cliniciens sur des images scanner (CT), malgré une prise en charge logicielle partielle. C’est une tâche complexe, sujette à la variabilité intra et interobservateur. Dans ce travail, nous présentons plusieurs méthodologies utilisant des techniques d’apprentissage profond pour segmenter automatiquement le coeur, la trachée, l’aorte et l’oesophage. En particulier, l’oesophage est particulièrement difficile à segmenter, en raison de l’absence de contraste et de variabilité de forme entre différents patients. Les réseaux profonds convolutionnels offrent aujourd’hui des performances de pointe en matière desegmentation sémantique, nous montrons d’abord comment un type spécifique d’architecture basée sur des skip connections peut améliorer la précision des résultats, par rapport à un réseau pleinement convolutionnel (FCN) standard. Dans une deuxième contribution, nous avons intégré des informations de contexte spatial au processus de segmentation, par le biais de réseaux collaboratifs, permettant les segmentations de chaque organe individuellement. Troisièmement, nous proposons une représentation différente des données, basée sur une carte de distance, utilisée en conjointement avec des réseaux adversariaux (GAN), comme un autre moyen de contraindre le contexte anatomique. Les méthodes proposées ont été évaluées sur une base d’images scanner de 60 patients. Les résultats montrent des résultats encourageants pour l’application clinique et souligne le potentiel des méthodes prenant en compte le contexte spatial dans la segmentationRadiotherapy is one of the options for treatment currently available for patients affected by cancer, one of the leading cause of deaths worldwide. Before radiotherapy, organs at risk (OAR) located near the target tumor, such as the heart, the lungs, the esophagus, etc. in thoracic cancer, must be outlined, in order to minimize the quantity of irradiation that they receive during treatment. Today, segmentation of the OAR is performed mainly manually by clinicians on Computed Tomography (CT) images, despite some partial software support. It is a tedious task, prone to intra and inter-observer variability. In this work, we present several frameworks using deep learning techniques to automatically segment the heart, trachea, aorta and esophagus. In particular, the esophagus is notably challenging to segment, due to the lack of surrounding contrast and shape variability across different patients. As deep networks and in particular fully convolutional networks offer now state of the art performance for semantic segmentation, we first show how a specific type of architecture based on skip connections can improve the accuracy of the results. As a second contribution, we demonstrate that context information can be of vital importance in the segmentation task, where we propose the use of two collaborative networks. Third, we propose a different, distance aware representation of the data, which is then used in junction with adversarial networks, as another way to constrain the anatomical context. All the proposed methods have been tested on 60 patients with 3D-CT scans, showing good performance compared with other methods
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Roman, Jimenez Geoffrey. "Analyse des images de tomographie par émission de positons pour la prédiction de récidive du cancer du col de l'utérus." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S037/document.
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Ces travaux de thèse s'inscrivent dans le contexte de la prédiction de la récidive en radiothérapie du cancer de l'utérus. L'objectif était d'analyser les images de tomographie par émission de positons (TEP) au 18F-fluorodésoxyglucose (18F-FDG) en vue d'en extraire des paramètres quantitatifs statistiquement corrélés aux événements de récidive. Six études ont été réalisées afin de répondre aux différentes problématiques soulevées par l'analyse des images 18F-FDG TEP telles que la présence d'artefact, l'isolation du métabolisme tumoral ou l'évaluation du signal en cours de traitement. Les études statistiques ont porté sur l'analyse de paramètres reflétant l'intensité, la forme et la texture du métabolisme tumoral avant, et en cours de traitement. À l'issue de ces travaux, le volume métabolique tumoral pré-thérapeutique ainsi que la glycolyse totale de la lésion per-thérapeutique apparaissent comme les paramètres les plus prometteurs pour la prédiction de récidive de cancers du col de l'utérus. De plus, il apparaît que la combinaison de ces paramètres avec d'autres caractéristiques de texture ou de forme, à l'aide de modèles statistiques d'apprentissage supervisé ou de modèles de régression plus classiques, ont permis d'augmenter la prédiction des événements de récidiveThis thesis deals with the issue of predicting the recurrence within the context of cervical cancer radiotherapy. The objective was to analyze positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) to extract quantitative parameters that could show statistical correlation with tumor recurrence. Six study were performed to address 18F-FDG PET imaging issues such as the presence of bladder uptake artifacts, tumor segmentation impact, as well as the analysis of tumor evolution along the treatment. Statistical analyses were performed among parameters reflecting intensity, shape and texture of the tumor metabolism before, and during treatment. Results show that the pre-treatment metabolic tumor volume and the per-treatment total lesion glycolysis are the most promising parameters for cervical cancer recurrence prediction. In addition, combinations of these parameters with shape descriptors and texture features, using machine-learning methods or regression models, are able to increase the prediction capability
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Chiu, Siu-hau, and 招兆厚. "A search for optimal radiation therapy technique for lung tumours stereotactic body radiation therapy (SBRT) : dosimetric comparison of 3D conformal radiotherapy, static gantry intensity modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) with flattening filter (FF) or flattening filter-free (FFF) beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196549.
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Materials/Methods:
Ten patients who underwent thoracic SBRT with primary stage I (T1/2N0) lung cancer or oligometastatic lung lesion, with PTV diameter ≤ 5cm were selected and were immobilized with Easyfoam or Vac-Lock. Planned/treated with inspiratory breath-hold (25 seconds, 70 to 80% of vital capacity) assisted with Active Breathing Control (ABC). Four treatment plans: non-coplanar 3DCRT, coplanar static gantry IMRT, coplanar VMAT (FF) and VMAT (FFF) were generated. Field arrangements, either static fields or partial arcs (duration=20 sec) were used to avoid direct beam entry to contralateral lung. All plans were compared in terms of dosimetric performance included dose to PTV or organs at risk (OAR), high/low dose spillage, integral dose (body and lungs), dose delivery efficiency (MU/Gy) and estimated beam-on time (BOT) with reference to the RTOG 0813 protocol.
Results:
All plans complied with RTOG 0813 protocol. VMAT (FF/ FFF) techniques improved target coverage and dose conformity, with the highest conformity number (CN > 0.91), compared to IMRT (0.88) and 3DCRT (0.85). The control of high dose spillage (NT>105% and CI) for IMRT (3.04% and 1.08) and VMAT (FF/ FFF) (1.08/ 1.06% and 1.03/ 1.04) techniques were comparable (p > 0.05) and significantly better than 3DCRT (4.22% and 1.11, p < 0.005) technique. In addition, VMAT (FF/ FFF) techniques performed the best in controlling low dose spillage (D2cm and R50%) compared with IMRT (reduction: 4.7%, p=0.036 and >5.9%, p = 0.009) and 3DCRT (reduction: > 16.3%, p < 0.001 and > 10%, p = 0.002). Benefits of rapid and isotropic dose fall-off were shown from superior tissue sparing (reduction ranges from 3.2% up to 67%) of ipsilateral brachial plexus, skin (0-5mm), great vessels and ribs. Also lung V10, V12.5, esophagus and heart tend to receive lower dose with VMAT technique. The relatively lower integral dose to whole body (> 3Gy∙L reduction, p < 0.013) and ipsilateral lung (0.65Gy∙L reduction, p = 0.025) compared with 3DCRT, were associated with lower risk of radiation induced cancers. The MU/Gy and BOT were substantial lower for VMAT (FF) (22.4% and 32.4%) compared with IMRT. Apart from higher (7%) maximum skin dose, dosimetric performance for VMAT (FFF) was comparable with VMAT (FF), with advantages of further reduction of MU/Gy (1.8% lesser), partial arc numbers (from 12-14 arcs down to 8 arcs) and BOT (35% shortened), owing to the increased dose output with flattening filter removal.
Conclusions:
VMAT (FF and FFF) plans maintained IMRT equivalent plan qualities, simultaneously enhanced the delivery efficiency with shortened BOT. VMAT (FFF) further reduced the required arcs number and BOT, significantly minimized the intra-fraction motions and more tolerable to patient with long SBRT treatment duration.published_or_final_version
Medicine
Master
Master of Medical Sciences
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Lhallabi, Abdessamad. "Evaluation des incertitudes dans la preparation et la realisation des traitements par radiotherapie transcutanee." Toulouse 3, 1987. http://www.theses.fr/1987TOU30076.
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LEVY, PIEDBOIS CHRISTINE. "Decrire et valoriser une discipline medico-technique : la prise en compte du pmsi en radiotherapie." Paris 7, 2001. http://www.theses.fr/2001PA077140.
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Pour verifier qu'un outil unique peut permettre une description du travail satisfaisante pour les praticiens et son financement, nous avons calcule a partir de la description faite par les experts, le cout des irradiations dans 2 etablissements, puis, prenant en compte l'ensemble des moyens disponibles, leurs couts reels partiels et complets. L'analyse des resultats nous font conclure que le cout partiel expert reflete le mieux les pratiques. Il permet de mesurer l'activite. Le cout reel est un outil gestionnaire. Le cout reel complet est l'equivalent d'un cout de production. Les facteurs predictifs de la variation des couts experts partiels ont ete recherches et examines d'un point de vue medical et gestionnaire pour ne retenir que 2 criteres pertinents. Le nombre de seances et le niveau de dosimetrie expliquent 75% de la variation des couts. Ils nous ont permis de construire 5 groupes homogenes de techniques correspondant a des niveaux de couts differents. Nous concluons qu'une description de l'activite a dire d'experts permet d'etablir des regles de description satisfaisante pour les medecins et les administratifs. Les catalogues d'actes n'apportent pas d'information supplementaire. Une vision globale de l'activite semble au contraire pouvoir favoriser la qualite.
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Mlynarski, Pawel. "Apprentissage profond pour la segmentation des tumeurs cérébrales et des organes à risque en radiothérapie." Thesis, Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR4084.
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Les images médicales jouent un rôle important dans le diagnostic et la prise en charge des cancers. Les oncologues analysent des images pour déterminer les différentes caractéristiques de la tumeur, pour proposer un traitement adapté et suivre l'évolution de la maladie. L'objectif de cette thèse est de proposer des méthodes efficaces de segmentation automatique des tumeurs cérébrales et des organes à risque dans le contexte de la radiothérapie, à partir des images de résonance magnétique (IRM). Premièrement, nous nous intéressons à la segmentation des tumeurs cérébrales en utilisant des réseaux neuronaux convolutifs entrainés sur des IRM segmentés par des experts. Nous proposons un modèle de segmentation ayant un grand champ récepteur 3D tout en étant efficace en termes de complexité de calcul, en combinant des réseaux neuronaux convolutifs 2D et 3D. Nous abordons aussi les problèmes liés à l'utilisation conjointe des différentes séquences IRM (T1, T2, FLAIR). Nous introduisons ensuite un modèle de segmentation qui est entrainé avec des images faiblement annotées en complément des images segmentées, souvent disponibles en quantités très limitées du fait de leur coût. Nous montrons que ce niveau mixte de supervision améliore considérablement la performance de segmentation quand le nombre d'images entièrement annotées est limité. Finalement, nous proposons une méthodologie pour segmenter, de manière cohérente anatomiquement, les organes à risque dans le contexte de la radiothérapie des tumeurs cérébrales. Les segmentations produites par notre système sur un ensemble d'IRM acquis dans le Centre Antoine Lacassagne (Nice) sont évaluées par un radiothérapeute expérimentéMedical images play an important role in cancer diagnosis and treatment. Oncologists analyze images to determine the different characteristics of the cancer, to plan the therapy and to observe the evolution of the disease. The objective of this thesis is to propose efficient methods for automatic segmentation of brain tumors and organs at risk in the context of radiotherapy planning, using Magnetic Resonance (MR) images. First, we focus on segmentation of brain tumors using Convolutional Neural Networks (CNN) trained on MRIs manually segmented by experts. We propose a segmentation model having a large 3D receptive field while being efficient in terms of computational complexity, based on combination of 2D and 3D CNNs. We also address problems related to the joint use of several MRI sequences (T1, T2, FLAIR). Second, we introduce a segmentation model which is trained using weakly-annotated images in addition to fully-annotated images (with voxelwise labels), which are usually available in very limited quantities due to their cost. We show that this mixed level of supervision considerably improves the segmentation accuracy when the number of fully-annotated images is limited.\\ Finally, we propose a methodology for an anatomy-consistent segmentation of organs at risk in the context of radiotherapy of brain tumors. The segmentations produced by our system on a set of MRIs acquired in the Centre Antoine Lacassagne (Nice, France) are evaluated by an experienced radiotherapist
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Dolz, Jose. "Vers la segmentation automatique des organes à risque dans le contexte de la prise en charge des tumeurs cérébrales par l’application des technologies de classification de deep learning." Thesis, Lille 2, 2016. http://www.theses.fr/2016LIL2S059/document.
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Les tumeurs cérébrales sont une cause majeure de décès et d'invalidité dans le monde, ce qui représente 14,1 millions de nouveaux cas de cancer et 8,2 millions de décès en 2012. La radiothérapie et la radiochirurgie sont parmi l'arsenal de techniques disponibles pour les traiter. Ces deux techniques s’appuient sur une irradiation importante nécessitant une définition précise de la tumeur et des tissus sains environnants. Dans la pratique, cette délinéation est principalement réalisée manuellement par des experts avec éventuellement un faible support informatique d’aide à la segmentation. Il en découle que le processus est fastidieux et particulièrement chronophage avec une variabilité inter ou intra observateur significative. Une part importante du temps médical s’avère donc nécessaire à la segmentation de ces images médicales. L’automatisation du processus doit permettre d’obtenir des ensembles de contours plus rapidement, reproductibles et acceptés par la majorité des oncologues en vue d'améliorer la qualité du traitement. En outre, toute méthode permettant de réduire la part médicale nécessaire à la délinéation contribue à optimiser la prise en charge globale par une utilisation plus rationnelle et efficace des compétences de l'oncologue.De nos jours, les techniques de segmentation automatique sont rarement utilisées en routine clinique. Le cas échéant, elles s’appuient sur des étapes préalables de recalages d’images. Ces techniques sont basées sur l’exploitation d’informations anatomiques annotées en amont par des experts sur un « patient type ». Ces données annotées sont communément appelées « Atlas » et sont déformées afin de se conformer à la morphologie du patient en vue de l’extraction des contours par appariement des zones d’intérêt. La qualité des contours obtenus dépend directement de la qualité de l’algorithme de recalage. Néanmoins, ces techniques de recalage intègrent des modèles de régularisation du champ de déformations dont les paramètres restent complexes à régler et la qualité difficile à évaluer. L’intégration d’outils d’assistance à la délinéation reste donc aujourd’hui un enjeu important pour l’amélioration de la pratique clinique.L'objectif principal de cette thèse est de fournir aux spécialistes médicaux (radiothérapeute, neurochirurgien, radiologue) des outils automatiques pour segmenter les organes à risque des patients bénéficiant d’une prise en charge de tumeurs cérébrales par radiochirurgie ou radiothérapie.Pour réaliser cet objectif, les principales contributions de cette thèse sont présentées sur deux axes principaux. Tout d'abord, nous considérons l'utilisation de l'un des derniers sujets d'actualité dans l'intelligence artificielle pour résoudre le problème de la segmentation, à savoir le «deep learning ». Cet ensemble de techniques présente des avantages par rapport aux méthodes d'apprentissage statistiques classiques (Machine Learning en anglais). Le deuxième axe est dédié à l'étude des caractéristiques d’images utilisées pour la segmentation (principalement les textures et informations contextuelles des images IRM). Ces caractéristiques, absentes des méthodes classiques d'apprentissage statistique pour la segmentation des organes à risque, conduisent à des améliorations significatives des performances de segmentation. Nous proposons donc l'inclusion de ces fonctionnalités dans un algorithme de réseau de neurone profond (deep learning en anglais) pour segmenter les organes à risque du cerveau.Nous démontrons dans ce travail la possibilité d'utiliser un tel système de classification basée sur techniques de « deep learning » pour ce problème particulier. Finalement, la méthodologie développée conduit à des performances accrues tant sur le plan de la précision que de l’efficacitéBrain cancer is a leading cause of death and disability worldwide, accounting for 14.1 million of new cancer cases and 8.2 million deaths only in 2012. Radiotherapy and radiosurgery are among the arsenal of available techniques to treat it. Because both techniques involve the delivery of a very high dose of radiation, tumor as well as surrounding healthy tissues must be precisely delineated. In practice, delineation is manually performed by experts, or with very few machine assistance. Thus, it is a highly time consuming process with significant variation between labels produced by different experts. Radiation oncologists, radiology technologists, and other medical specialists spend, therefore, a substantial portion of their time to medical image segmentation. If by automating this process it is possible to achieve a more repeatable set of contours that can be agreed upon by the majority of oncologists, this would improve the quality of treatment. Additionally, any method that can reduce the time taken to perform this step will increase patient throughput and make more effective use of the skills of the oncologist.Nowadays, automatic segmentation techniques are rarely employed in clinical routine. In case they are, they typically rely on registration approaches. In these techniques, anatomical information is exploited by means of images already annotated by experts, referred to as atlases, to be deformed and matched on the patient under examination. The quality of the deformed contours directly depends on the quality of the deformation. Nevertheless, registration techniques encompass regularization models of the deformation field, whose parameters are complex to adjust, and its quality is difficult to evaluate. Integration of tools that assist in the segmentation task is therefore highly expected in clinical practice.The main objective of this thesis is therefore to provide radio-oncology specialists with automatic tools to delineate organs at risk of patients undergoing brain radiotherapy or stereotactic radiosurgery. To achieve this goal, main contributions of this thesis are presented on two major axes. First, we consider the use of one of the latest hot topics in artificial intelligence to tackle the segmentation problem, i.e. deep learning. This set of techniques presents some advantages with respect to classical machine learning methods, which will be exploited throughout this thesis. The second axis is dedicated to the consideration of proposed image features mainly associated with texture and contextual information of MR images. These features, which are not present in classical machine learning based methods to segment brain structures, led to improvements on the segmentation performance. We therefore propose the inclusion of these features into a deep network.We demonstrate in this work the feasibility of using such deep learning based classification scheme for this particular problem. We show that the proposed method leads to high performance, both in accuracy and efficiency. We also show that automatic segmentations provided by our method lie on the variability of the experts. Results demonstrate that our method does not only outperform a state-of-the-art classifier, but also provides results that would be usable in the radiation treatment planning
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Guinin, Maxime. "Segmentation 3D des organes à risque du tronc masculin à partir d'images anatomiques TDM et IRM à l'aide de méthodes hybrides." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR019/document.
Full textAbstract:
Le cancer de la prostate est une cause majeure de décès dans le monde. La radiothérapie externe est une des techniques utilisée pour traiter ce cancer. Pour ce faire, la segmentation de la prostate et de ses organes à risque (OAR) associés (le rectum, la vessie et les têtes fémorales) est une étape majeure dans l’application du traitement. L’objectif de cette thèse est de fournir des outils afin de segmenter la prostate et les OAR de manière automatique ou semi-automatique. Plusieurs approches ont été proposées ces dernières années pour répondre à ces problématiques. Les OAR possédant un contraste relativement bon dans l’image, nous nous sommes orientés vers une approche semi-automatique de leur segmentation, consistant en une sur-segmentation de l’image en petites régions homogènes appelées superpixels. L’utilisateur de la méthode choisit ensuite de labelliser quelques superpixels dans les OAR comme des germes. Enfin, la méthode segmente les OAR grâce à une diffusion sur le graphe (à partir des germes) construit par des superpixels. Quant à la segmentation de la prostate, un sous-volume de l’image appelé VOI (Volume Of Interest), dans lequel se trouve la prostate, est tout d’abord défini. À l’intérieur de ce VOI, la segmentation de la prostate est réalisée. Un dictionnaire composé des caractéristiques de textures extraites sur chaque patch du VOI est d’abord construit. La sélection de caractéristiques du dictionnaire sous contraintes parcimonieuses permet ensuite de trouver celles qui sont le plus informatives. Enfin, basé sur ces caractéristiques sélectionnées, une propagation de label de patch sous contrainte parcimonieuse est appliquée pour segmenter la prostate à deux échelles, superpixels et pixels. Notre méthode a été évaluée sur des images TDM du Centre Henri Becquerel et IRM du challenge ISBI 2013 avec des résultats prometteursProstate cancer is a leading cause of death worldwide. External radiotherapy is one of the techniques used to this disease. In order to achieve this, the segmentation of the prostate and its associated organs at risk (OAR) (rectum, bladder and femoral heads) is a major step in the application of the treatment. The objective of this thesis is to provide tools to segment prostate and OAR automatically or semi-automatically. Several approaches have been proposed in recent years to address these issues. As OAR have a relatively good contrast in the image, we have focused on a semi-automatic approach to segment them, consisting of an over-segmentation of the image into small homogeneous regions called superpixels. Then, the user labels some superpixels in the OAR as germs. Finally, the OAR segmentation is performed by a graph diffusion (from germs) constructed by superpixels. Regarding the prostate segmentation, a sub-volume of the image called VOI (Volume Of Interest), in which the prostate is located, is first defined. The prostate segmentation is performed within this VOI. A dictionary composed of the texture characteristics extracted on each patch of the VOI is first constructed. Then, the selection of characteristics of the dictionary under parsimonious constraints allows to find the most informative ones. Finally, based on these selected characteristics, patch label propagation under parsimonious constraint is applied to segment the prostate at two scales, superpixels and pixels. Our method was evaluated with promising results on TDM images of the Henri Becquerel Center and IRM of the 2013 ISBI challenge
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LASNE, JACOB ISABELLE. "Lymphoedeme du membre superieur apres traitement radiochirurgical d'un cancer du sein : a propos de 64 patientes traitees selon la technique de van der molen." Lille 2, 1990. http://www.theses.fr/1990LIL2M172.
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Montay, gruel Pierre-Gabriel. "Réponse du cerveau sain, des cellules souches neuronales et du glioblastome à une nouvelle technique de radiothérapie Flash." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS147.
Full textAbstract:
De nos jours, plus de 50% des patients porteurs de tumeur bénéficient d’un traitement de radiothérapie. Malgré de récentes avancées technologiques augmentant de la précision des traitements, la radiothérapie encéphalique induit toujours des effets secondaires invalidants et irréversibles. Ce constat justifie le développement de nouvelles techniques de radiothérapie. Des études précliniques réalisées sur l’irradiation FLASH ont montré la possibilité de maintenir un effet anti-tumoral tout en réduisant drastiquement les effets secondaires sur le tissu sain. Cet effet a été appelé « l’effet FLASH ». Cette technologie consistant à délivrer des doses à des débits supérieurs à 40 Gy/s a généré un intérêt important pour l’augmentation de l’index thérapeutique de la radiothérapie.Ce travail de thèse vise à étudier l’effet anti-tumoral de l’irradiation FLASH sur des modèles précliniques de glioblastome, tout en évaluant ses effets sur le tissu cérébral sain. Des modèles murins de glioblastome sous-cutané, orthotopique et transgénique ont été développés et irradiés grâce à un prototype d’accélérateur linéaire d’électrons délivrant une irradiation FLASH ou conventionnelle. De plus, des modèles murins d’irradiation encéphalique ont été mis au point afin d’investiguer les effets cellulaires et les altérations fonctionnelles induites par l’irradiation FLASH. La division cellulaire et la structure neuronale dans l’hippocampe ont été évaluées, ainsi que des aspects plus physiopathologiques comme la neuroinflammation ou l’astrogliose. Un panel de tests cognitifs a également été utilisé afin d’étudier les altérations cognitives induites par l’irradiation encéphalique. Enfin, les évènements physico-chimiques engendrés par l’irradiation FLASH et plus particulièrement le rôle de la consommation de dioxygène lors de l’irradiation, ont été analysés afin d’élucider les mécanismes qui supportent l’effet FLASH.Dans tous les modèles étudiés, l’irradiation FLASH a présenté un effet anti-tumoral au minimum similaire à celui de l’irradiation conventionnelle. Les modèles d’irradiation encéphalique ont montré une innocuité de l’irradiation FLASH sur le tissu cérébral sain, avec une absence de déficits cognitifs pour des débits de dose supérieurs à 100 Gy/s, couplée à une absence d’altération de la division cellulaire et de la structure neuronale dans l’hippocampe, une absence de neuroinflammation et d’astrogliose. De plus, des résultats similaires ont été observés avec l’utilisation de rayons X délivrés à ultra-haut débit par un rayonnement synchrotron. Sur le plan mécanistique, la réversion des effets protecteurs de l’irradiation FLASH par l’induction d’une hyperoxie, l’absence d’effet de l’anoxie sur l’effet anti-tumoral et la production de moins de radicaux libres souligne le rôle primaire du dioxygène dans l’effet FLASH.L’ensemble de ces résultats illustre la possibilité d’augmenter l’index thérapeutique de la radiothérapie en utilisant l’irradiation FLASH. En effet, cette nouvelle technologie permet de préserver le tissu sain contre les toxicités radio-induites lorsque l’irradiation est délivrée à des débits supérieurs à 100 Gy/s, tout en gardant un effet anti-tumoral équivalent à l’irradiation conventionnelle. D’après ces résultats précliniques et un transfert clinique dans un futur proche, l’irradiation FLASH pourrait devenir une technique de choix dans le traitement des tumeurs par radiothérapieNowadays, more than 50% of cancer patients can benefit from a radiation-therapy treatment. Despite important technological advance and dose delivery precision, encephalic radiation-therapy still induces large and irreversible side effects in pediatric and adult cancer patients, justifying the urge to develop new radiation-therapy techniques. Preclinical studies on FLASH irradiation (FLASH-RT) showed a possibility to efficiently treat the tumors, without inducing drastic side-effects on the normal tissue, by increasing the dose-rate over 40 Gy/s. This so called “FLASH effect” set off an important interest in this new irradiation technology to increase the therapeutic ratio of radiation-therapy.This PhD work aimed at investigating the antitumor effect of FLASH-RT on brain tumor models along with the assessment of the ultra-high dose-rate irradiation effects on the normal brain tissue. In this context, subcutaneous, orthotopic and transgenic glioblastoma murine models were used to investigate the curative effect of FLASH irradiation delivered with an experimental LINAC available at the CHUV, and able to deliver both conventional and FLASH irradiation. Moreover, murine models of whole brain irradiation were developed to investigate the radiation-induced cellular and functional alterations at early and late time-points post-FLASH-RT. These models were used to decipher the cellular effectors involved in the brain’s radiation response including hippocampal cell-division and neuronal responses but also more physio pathological aspects as radiation-induced reactive astrogliosis and neuroinflammation. A panel of well-defined cognitive tests was also developed to investigate the radiation-induced cognitive alterations. Eventually, the physio-chemical primary events induced by FLASH-RT, and particularly the role of dioxygen consumption, were investigated to decipher the mechanisms that underlie the FLASH effect.In all investigated tumor models, FLASH-RT displayed an efficient antitumor effect at least similar to the conventional irradiation. The whole brain irradiation models showed an innocuousness of FLASH-RT on the normal brain tissue, with an absence of cognitive deficit several months after irradiation at dose-rates above 100 Gy/s, coupled with a preservation of hippocampal cell division and neuronal structure. This protection was also observed at the physio pathological level with an absence of astrogliosis and neuroinflammation. Moreover, these results were reproduced with ultra-high dose-rate X-Rays delivered with a synchrotron light source. On the mechanistic side, the reversion of the protective effects of FLASH-RT by hyperoxia, and the absence of effect of anoxia on the antitumor effect, along with a decreased ROS production underlies the primary role of dioxygen consumption during ultra-high dose-rate irradiation.Altogether, these unique results depict the possibility to increase the therapeutic index of radiation-therapy by the use of FLASH-RT. Indeed, this new irradiation technology preserves the normal brain tissue from radiation-induced toxicities by increasing the dose-rate over 100 Gy/s, while keeping an antitumor effect equivalent to the conventional dose-rate irradiation. According to these preclinical results and an upcoming clinical translation, FLASH-RT might become a major contributor to the cancer treatment by radiation therapy
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Lafond, Caroline. "Analyse et optimisation des performances de la technique VMAT pour son utilisation en radiothérapie." Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00980181.
Full textAbstract:
La technique de radiothérapie VMAT (Volumetric Modulated Arc Therapy), diffusée en 2009, combine les avantages des techniques d'arc thérapie dynamique aux avantages des techniques de radiothérapie conformationnelle avec modulation d'intensité (RCMI) par faisceaux stationnaires. L'objectif de la thèse est de rendre optimales les conditions de mise en œuvre du VMAT autour d'un accélérateur linéaire d'électrons Synergy/Elekta afin de sécuriser la technique et de pouvoir bénéficier de l'apport clinique potentiellement attendu. Sur la base d'une analyse de l'influence des différents paramètres de la chaîne de traitement, nous proposons des éléments d'optimisation du traitement à la fois sur la planification dosimétrique et sur le contrôle de son exécution sur la machine. Nous montrons que si la qualité de l'optimisation de la technique dépend des caractéristiques intrinsèques de l'accélérateur, elle est également fortement influencée par le paramétrage du système de planification des traitements (TPS). Nous mettons en évidence des différences comparées des collimateurs Beam Modulateur (largeur de lames de 4 mm) et MLCi2 (largeur de lames de 10 mm) tant sur le plan de la distribution de dose obtenue que sur l'efficience. Nous montrons que, si pour deux principaux TPS commercialisés (Pinnacle/Philips et Monaco/Elekta) les distributions de dose aux volumes cibles sont peu modifiées, les différences de méthodes implémentées influencent la distribution de dose aux tissus sains. Nous proposons des programmes de contrôles de qualité au niveau de l'accélérateur, des plans dosimétriques de traitement et de l'exécution des traitements. Afin de garantir un niveau de confiance élevé sur la dose délivrée, nous proposons une méthode d'évaluation de la fluence délivrée en cours de traitement basée sur l'analyse des paramètres machines. Nous établissons que le processus de traitement VMAT optimisé fournit des performances de qualité supérieure que les techniques de RCMI par faisceaux stationnaires pour quatre localisations tumorales majeures étudiées.
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Cowen, Didier. "Irradiation corporelle totale fractionnée avant allogreffe de moelle osseuse : technique d'arcthérapie et résultats à propos de 104 patients." Bordeaux 2, 1990. http://www.theses.fr/1990BOR23051.
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Pennequin, Jean-Claude. "Reconnaissance automatique de formes dans des images de simulation et de traitement en radiothérapie." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL018N.
Full textAbstract:
La radiothérapie externe est une thérapeutique utilisant les radiations ionisantes pour traiter les cancers locorégionaux. Afin de permettre le contrôle du bon positionnement du patient, des caches de protection et du champ d'irradiation, des images de simulation et de traitement sont comparées. Les limites du champ d'irradiation sont détectées par la méthode de sommation et les limites des caches de protection par la transformée de Hough. Les formes repérées du patient sont traitées comme une chaine de caractères code suivant la technique de Freeman. Afin de réduire les temps de calcul, la technique de corrélation est appliquée dans une seconde période. La corrélation entre les deux images se fait sur des images brutes, de contours et squelettisées. Le maximum de corrélation permet de localiser les coordonnées du meilleur rapport entre l'image de simulation et de traitement. Les résultats sont satisfaisants puisqu'ils permettent de localiser des différences de quelques millimètres
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Wang, Zhonglu. "Design of a Boron Neutron Capture Enhanced Fast Neutron Therapy Assembly." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14100.
Full textAbstract:
A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator near the patient¡¯s head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm2 treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm2 collimation was 21.9% per 100-ppm B-10 for a 5.0-cm tungsten filter and 29.8% for an 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively.
To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm2 collimator. Five 1.0-cm thick 20x20 cm2 tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm 10B) to measure dose due to boron neutron capture. The measured dose enhancement at 5.0-cm depth in the head phantom for the 5.0-cm thick tungsten filter is (16.6 ¡À 1.8)%, which agrees well with the MCNP simulation of the simplified BNCEFNT assembly, (16.4¡À 0.5)%. The error in the calculated dose enhancement only considers the statistical uncertainties. The total dose rate measured at 5.0-cm depth using the non-borated ion chamber is (0.765 ¡À 0.076) Gy/MU, about 61% of the fast neutron standard dose rate (1.255Gy/MU) at 5.0-cm depth for the standard 10x10 cm2 treatment beam.
The increased doses to other organs due to the use of the BNCEFNT assembly were calculated using MCNP5 and a MIRD phantom.
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Puntous, Maryse. "Modalites et résultats d'un protocole de conditionnement de greffe de moelle osseuse par cytosine-arabinoside à haute dose associée au cyclophosphamide et a l'irradiation corporelle totale dans le traitement de leucémies de mauvais pronostic : 25 observations." Bordeaux 2, 1990. http://www.theses.fr/1990BOR23102.
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