Intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) have been introduced in radiation therapy to achieve highly conformal dose distributions around the tumour while minimizing dose to surrounding normal tissues. These techniques have increased the need for comprehensive quality assurance tests, to verify that customized patient treatment plans are accurately delivered during treatment. In vivo dose verification, performed during treatment delivery, confirms that the actual dose delivered is the same as the prescribed dose, helping to reduce treatment delivery errors. In vivo measurements may be accomplished using entrance or exit detectors. The objective of this project is to investigate a novel entrance detector designed for in vivo dose verification. This thesis is separated into three main investigations, focusing on a prototype entrance transmission detector (TRD) developed by IBA Dosimetry, Germany. First contaminant electrons generated by the TRD in a 6 MV photon beam were investigated using Monte Carlo (MC) simulation. This study demonstrates that modification of the contaminant electron model in the treatment planning system is required for accurate patient dose calculation in buildup regions when using the device. Second, the ability of the TRD to accurately measure dose from IMRT and VMAT was investigated by characterising the spatial resolution of the device. This was accomplished by measuring the point spread function with further validation provided by MC simulation. Comparisons of measured and calculated doses show that the spatial resolution of the TRD allows for measurement of clinical IMRT fields within acceptable tolerance. Finally, a new general research tool was developed to perform MC simulations for VMAT and IMRT treatments, simultaneously tracking dose deposition in both the patient CT geometry and an arbitrary planar detector system, generalized to handle either entrance or exit orientations. It was demonstrated that the tool accurately simulates dose to the patient CT and planar detector geometries. The tool has been made freely available to the medical physics research community to help advance the development of in vivo planar detectors. In conclusion, this thesis presents several investigations that improve the understanding of a novel entrance detector designed for patient in vivo dosimetry.

Intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) have been introduced in radiation therapy to achieve highly conformal dose distributions around the tumour while minimizing dose to surrounding normal tissues. These techniques have increased the need for comprehensive quality assurance tests, to verify that customized patient treatment plans are accurately delivered during treatment. In vivo dose verification, performed during treatment delivery, confirms that the actual dose delivered is the same as the prescribed dose, helping to reduce treatment delivery errors. In vivo measurements may be accomplished using entrance or exit detectors. The objective of this project is to investigate a novel entrance detector designed for in vivo dose verification. This thesis is separated into three main investigations, focusing on a prototype entrance transmission detector (TRD) developed by IBA Dosimetry, Germany. First contaminant electrons generated by the TRD in a 6 MV photon beam were investigated using Monte Carlo (MC) simulation. This study demonstrates that modification of the contaminant electron model in the treatment planning system is required for accurate patient dose calculation in buildup regions when using the device. Second, the ability of the TRD to accurately measure dose from IMRT and VMAT was investigated by characterising the spatial resolution of the device. This was accomplished by measuring the point spread function with further validation provided by MC simulation. Comparisons of measured and calculated doses show that the spatial resolution of the TRD allows for measurement of clinical IMRT fields within acceptable tolerance. Finally, a new general research tool was developed to perform MC simulations for VMAT and IMRT treatments, simultaneously tracking dose deposition in both the patient CT geometry and an arbitrary planar detector system, generalized to handle either entrance or exit orientations. It was demonstrated that the tool accurately simulates dose to the patient CT and planar detector geometries. The tool has been made freely available to the medical physics research community to help advance the development of in vivo planar detectors. In conclusion, this thesis presents several investigations that improve the understanding of a novel entrance detector designed for patient in vivo dosimetry.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21619号 / 医博第4425号 / 新制||医||1033(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 増永 慎一郎, 教授 松村 由美, 教授 富樫 かおり / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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Projekto tikslas – sukurti elektroninį portalą klientams kurio pagalba jie galėtų efektyviai dirbti naudojantis naujausiomis technologijomis. Uždaviniai: • sukurti patogią ir patrauklią vartotojo sąsają; • paanalizuoti nedidelės firmos veiklą ir sukurti kompiuterizuotą prekių užsakymų ir paslaugų atlikimo sistemą; • pateikti labiausiai perkamos produkcijos bei atliekamų užsakymų analizę; • sukurti savitą ir patrauklią ir lengvai valdomą sąsają; • kaupti realizuojamų prekių ir atliktų paslaugų duomenų bazę; • sukurti lanksčia duomenų bazės atnaujinimo sistemą. Atlikus analogiškos paskirties svetainių bei portalų analizę, buvo nustatyti svetainei keliami reikalavimai: paprasta vartotojo sąsaja, nekelianti didelių reikalavimų techninei ir programinei įrangai, nesudėtingas valdymas, patogi ir aiški, intuityviai suprantama vartotojo sąsaja, informatyvi, aiškiai ir glaustai pateikiama informacija. Sukurtas elektroninės parduotuvės portalas leidžia analizuoti informacijos srautus, todėl būtinas techninių ir programinių priemonių kompleksas, užtikrinantis informacijos analizę ir apdorojimą realiame laike bei automatizuotą atitinkamų sprendimų priėmimą. Taip galima būtų parinkti tinkamus tinkamų prekių tiekimo partnerius kiekvienu atveju ir vykdyti pelningiausias verslo transakcijas. Projektuojant šį portalą nemažai sužinota apie naujas programavimo technologijas, priemones, palengvinančias projektavimo ir programavimo procesus bei įvairias su tuo susijusias problemas. Įgyta gera... [toliau žr. visą tekstą] / The purpose of the project is to establish for clients an electronic portal with the help of which they can effectively work by making use of the latest technologies. Tasks: • to create a convenient and attractive user interface; • to analyse the activity of a small firm and establish a computerised system for ordering goods and performing services; • to provide analysis of the most frequently purchased goods most frequently filled orders; • to create a distinctive, attractive, and easily controlled interface; • to build a database of sold goods and performed services; • to create a flexible system for renewing the database. Having performed an analysis of analogous Web sites and portals, the requirements for the Web site were determined: a simple user interface that does not impose any great requirements for hardware or software, uncomplicated control, and a convenient, clear, and intuitive user interface with useful, clear, and concise information. The resulting electronic shopping portal permits information flows to be analysed, therefore a system of hardware and software is essential in order to guarantee information analysis and processing in real time and automated decision-making. In this way, it would become possible to select the appropriate partners to supply the appropriate goods in every case and make the most profitable possible business transactions. In designing this portal, much was learned about new programming technologies, methods to ease the design and... [to full text]

Nowadays more and more radiotherapy departments use intensity modulated beams for treatment of patients. Intensity modulated radiotherapy (ImRT) is able to modificate intensity of radiation across the iradiated field. In this way it is posible to achieve better dose conformity than in conventional radiotherapy. Implementation of ImRT allows us to escalate dose to target volume with same side effects of organs at risk as in conventional radiotherapy or to reduce normal tissue complication - decrease dose to organ at risk with the same tumour dose. This fact reguires extension of our guality system to all network of delivery dose to patients, inclusive linear accelerator with multileaf collimator, treatment planning system, electronic portal imaging device and so on. Quality assurance is guaranteed both periodical user tests and independent verification of The State Office for Nuclear Safety. The aim of this work is finding the optimal and effective way for the verification treatment plans, determining criteria for evaluation measured results, proposing summary all aspects of radiation protection patients which are treate ionisation beams with intensity modulated radiotherapy. The optimization one of the principles of radiation protection will be provided by routin verification treatment plans.

Recent work has demonstrated improvement of image quality with low atomic number (Z) linear accelerator (linac) targets and energies as low as 3.5 MV compared to a standard 6 MV therapeutic beam. In this work, the incident electron beam energy has been lowered to energies between 1.90 and 2.35 MeV. The improvement of megavoltage planar image quality with the use of carbon and aluminum linac targets has been assessed compared to a standard 6 MV therapeutic beam. Common electronic portal imaging devices contain a 1.0 mm copper conversion plate to increase detection efficiency of a therapeutic megavoltage spectrum. When used in imaging with a photon beam generated with a low-Z target, the conversion plate attenuates a substantial proportion of photons in the diagnostic range, thereby reducing the achievable image quality. Image quality as a function of copper plate thickness has been assessed for planar imaging and cone beam computed tomography.