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Atualmente a maior parte dos tratamentos radioterápicos é feita através de irradiações com feixes de fótons de alta energia. Esses feixes se originam em fontes radioativas (de nuclídeos como o cobalto 60) ou são gerados em aceleradores lineares de elétrons. Para as medidas dosimétricas nesses feixes, uma das técnicas mais utilizada é a termoluminescência (TL) e, para a correta utilização dos dosímetros termoluminescentes (TLDs), é necessário conhecer suas características dosimétricas como, por exemplo, a variação da sua resposta com a energia do feixe de radiação. O objetivo desse trabalho foi estudar essa dependência energética da resposta TL de diversos materiais quando irradiados em feixes de fótons de alta energia. Para isso, foram obtidas curvas de resposta TL em função da dose absorvida em água para os LDs de LiF:Mg, Ti (TLD-100), fluorita natural brasileira, CaSO4:Dy, Mg2SiO4:Tb e l2O3:C irradiados em feixes gama de 60Co e de raios X de aceleradores lineares com potenciais de aceleração nominais de 6, 10, 15 e 18 MV. O estudo foi feito em uma faixa de doses equivalente à utilizada em fracionamentos padrão de tratamentos de radioterapia e os resultados demonstram que, nessas condições, não há variação maior que 3% na resposta TL em função da energia dos fótons. A relação entre a deposição e doses nos TLDs e a deposição de doses na água em função da variação da energia oi estudada por simulação de Monte Carlo (MC), através do código PENELOPE, e os resultados foram coerentes com os resultados experimentais. Os TLDs também foram irradiados com nêutrons térmicos e epitérmicos e apresentaram sensibilidade a esse tipo de radiação. No entanto, a coerência dos resultados experimentais e de MC (que não levaram em conta a presença de nêutrons), o estudo da variação da sensibilidade relativa com a energia e a análise das curvas de emissão dos TLDs levam à conclusão e que a influência na resposta TL devida a nêutrons que contaminam os feixes de fótons estudados, é desprezível para todos os materiais. Os resultados desse trabalho indicam que, para a faixa de doses e energias utilizadas rotineiramente na radioterapia, os TLDs de LiF:Mg, Ti (TLD-100), fluorita natural brasileira, CaSO4:Dy, Mg2SiO4:Tb e Al2O3:C podem ser utilizados sem a aplicação de fatores de correção para a energia do feixe. / Currently the majority of radiotherapy treatments are done by irradiation with high energy photon beams. These beams are emitted by radioactive sources (of nuclides such as cobalt 60) or generated in electron linear accelerators. For dosimetric measurements on these beams, one of the most used techniques is the thermoluminescence (TL). For the correct use of the thermoluminescent dosimeters (TLDs), it is necessary to know their dosimetric properties like, for example, the variation of their response with the energy of the radiation beam. The purpose of this study was to assess the energy response of various TL materials when irradiated with high energy photon beams. So, curves relating the TL response and absorbed dose to water were obtained for LiF:Mg, Ti (TLD-100), Brazilian natural fluorite, CaSO4:Dy, g2SiO4:Tb and Al2O3:C TLDs irradiated with gamma rays from a 60Co source and linear accelerator X ray beams with nominal accelerating potential of 6, 10, 15 and 18 MV. The study was done in a dose range similar to that used in standard fractionated radiotherapy treatments and the results show that under these conditions, there is no variation larger than 3% in the TL response as a function of photon energy. The relationship between the dose deposition in the TLD and the dose deposition in water in function of the photon energy was studied by Monte Carlo method (MC), using the PENELOPE code system, and the results were consistent with the experimental outcomes. The TLDs were also irradiated with thermal and epithermal neutrons and proved to be sensitive to them. However, the consistency of the experimental and MC results (which did not take into account the presence of neutrons), the study of the variation in TL relative sensitivity with the beam energy, and the TLD glow curve shape analysis lead to the conclusion that the influence on TL response due to neutron contamination in the therapeutic photon beams is negligible for all materials. The results indicate that for the range of doses and energies used routinely in radiotherapy, the LiF:Mg, Ti (TLD-100), Brazilian natural fluorite, CaSO4:Dy, Mg2SiO4:Tb and Al2O3:C TLDs can be used without applying any correction factors for the beam energy.

O Relatório Mundial do Câncer, a Agência Internacional Para Pesquisa no Câncer e a Organização Mundial da Saúde estimam que, a cada ano há 12,4 milhões de novos casos de câncer no mundo, havendo 7,6 milhões de mortes causadas pela doença, onde para os homens o mais recorrente é o câncer de próstata. Por isso, o tratamento de câncer de próstata, neste caso, por radioterapia deve apresentar elevada precisão. Um complicador para tal precisão pode ser a presença de próteses metálicas no fêmur e na pélvis, podendo ser unilateral ou bilateral. O objetivo deste trabalho foi analisar e comparar o tratamento radioterápico de próstata para três situações diferentes, com duas próteses, com uma prótese e sem nenhuma prótese através da dosimetria por Ressonância Paramagnética (EPR) utilizando o aminoácido alanina com dosímetro, que se baseia na determinação de radicais livres produzidos pela interação entre a radiação e a alanina através do registro do espectro da alanina irradiada. Para tal análise foi construído um simulador físico (phantom), com as medidas reais de um ser humano, feito de acrílico e água, simulando o tecido mole, e ossos humanos. Na região da próstata foi feita uma abertura cilíndrica onde foram inseridos os dosímetros de alanina compostos 95% de DL-alanina e 5% de Polivinil Álcool (PVA) com 3mm de diâmetro, 4 mm de comprimento e massa de 0,05 g. O phantom foi irradiado para cada situação, nas condições de tratamento em um acelerador linear Oncor Plus da Siemens com feixe de raios X de 6MV para quatro campos 10x10cm2 e uma dose de 2 Gy, onde as mesmas condições foram utilizadas para a calibração dos dosímetros. Os dosímetros foram analisados em um espectrômetro de banda X JEOL JES-FA200 (9.5 GHz). Através da curva de calibração e a amplitude da linha central do espectro foi possível calcular a dose obtida em cada dosímetro de DL-alanina obtendo uma variação de até 6,15% para as medidas da dose prescrita de 2 Gy. Os resultados mostraram-se semelhantes para as três situações estudadas, assim como calculado no sistema de planejamento. / The World Cancer Report, the International Agency for Research on Cancer and the World Health Organization estimates that each year there are 12.4 million new cases of cancer worldwide, with 7.6 million deaths from the disease, for which men is the most recurrent prostate cancer. Therefore, the treatment of prostate cancer, in this case by radiotherapy should have a high accuracy. A complicating factor for such precision may be the presence of metallic prosthesis in the femur and pelvis and may be unilateral or bilateral. The objective of this study was to analyze and compare the radiotherapy of prostate for three different situations, with two prostheses, with one prosthesis and without a prosthesis through dosimetry Paramagnetic Resonance (EPR) using the amino acid alanine with dosimeter, which is based on determining free radicals produced by the interaction between radiation and alanine by recording the spectrum of irradiated alanine. For this analysis we built a physical simulator (phantom), with the real measurements of a human being, made of acrylic and water, simulating soft tissue, and human bones. In the region of the prostate was made a cylindrical opening in which the dosimeters were inserted alanine compounds 95% DL-alanine and 5% Polyvinyl Alcohol (PVA) with 3mm diameter, 4 mm in length and mass of 0.05 g. The phantom was irradiated for each situation, the conditions of treatment in a linear accelerator Oncor Plus Siemens X-ray beam with 6mV for four fields of 10x10cm2 and a dose of 2 Gy, where the same conditions were used for calibration of the dosimeter. The dosimeters were analyzed in a JEOL X-band spectrometer JES-FA200 (9.5 GHz). Through the calibration curve and the amplitude of the centerline of the spectrum was possible to calculate the dose obtained in each of DL-alanine dosimeter obtaining a variation of up to 6.15% for the measurements of the prescribed dose of 2 Gy. The results were similar for the three cases studied, as calculated in the planning system.

Due to the difficulty of a complex commissioning technique for a multi energetic, multi-modality linear accelerator, I perform all the commissioning and acceptance testing for a TrueBeam linear accelerator with 4 megavoltage (MV) energies of which 2 are flattening filter-free (FFF) and 6 electron energies varying from 6 MeV to 20 MeV. A 2 dimensional (2D) water tank was used for scanning all the required field sizes for all the energies. The one dimensional (1D) water tank was used to collect all the output factors for all the photon fields sizes small to medium electron field sizes. For the large electron fields sizes, we had to use the 2D water tank. All the collected data was converted into a file type accepted by the planning system (Eclipse) and subsequently imported there. Treatment plans were generated using multiple forms of planning to verify the viability and quality of the beam data commissioned. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

This thesis presents interdisciplinary, collaborative research in the field of synchrotron microbeam radiation therapy (MRT). Synchrotron MRT is an experimental radiotherapy technique under consideration for clinical use, following demonstration of efficacy in tumour-bearing rodent models with remarkable sparing of normal tissue. A high flux, X-ray beam from a synchrotron is segmented into micro-planar arrays of narrow beams, typically 25 μm wide and with peak-to-peak separations of 200 μm. The radiobiological effect of MRT and the underlying cellular mechanisms are poorly understood. The ratio between dose in the ‘peaks’of the microbeams to the dose in the ‘valleys’, between the microbeams, has strong biological significance. However, there are difficulties in accurately measuring the dose distribution for MRT. The aim of this thesis is to address elements of both the dosimetric and radiobiological gaps that exist in the field of synchrotron MRT. A method of film dosimetry and microdensitometry was adapted in order to measure the peak-to-valley dose ratios for synchrotron MRT. Two types of radiochromic film were irradiated in a phantom and also flush against a microbeam collimator on beamline BL28B2 at the SPring-8 synchrotron. The HD-810 and EBT varieties of radiochromic film were used to record peak dose and valley dose respectively. In other experiments, a dose build-up effect was investigated and the half value layer of the beam with and without the microbeam collimator was measured to investigate the effect of the collimator on the beam quality. The valley dose obtained for films placed flush against the collimator was approximately 0.25% of the peak dose. Within the water phantom, the valley dose had increased to between 0.7–1.8% of the peak dose, depending on the depth in the phantom. We also demonstrated, experimentally and by Monte Carlo simulation, that the dose is not maximal on the surface and that there is a dose build-up effect. The microbeam collimator did not make an appreciable difference to the beam quality. The measured values of peak-to-valley dose ratio were higher than those predicted by previously published Monte Carlo simulation papers. For the radiobiological studies, planar (560 Gy) or cross-planar (2 x 280 Gy or 2 x 560 Gy) irradiations were delivered to mice inoculated with mammary tumours in their leg, on beamline BL28B2 at the SPring-8 synchrotron. Immunohistochemical staining for DNA double strand breaks, proliferation and apoptosis was performed on irradiated tissue sections. The MRT response was compared to conventional radiotherapy at 11, 22 or 44 Gy. The results of the study provides the first evidence for a differential tissue response at a cellular level between normal and tumour tissues following synchrotron MRT. Within 24 hours of MRT to tumour, obvious cell migration had occurred into and out of irradiated zones. MRT-irradiated tumours showed significantly less proliferative capacity by 24 hours post-irradiation (P = 0.002). Median survival times for EMT-6.5 and 67NR tumour-bearing mice following MRT (2 x 560 Gy) and conventional radiotherapy (22 Gy) increased significantly compared to unirradiated controls (P < 0.0005). However, there was markedly less normal tissue damage from MRT than from conventional radiotherapy. MRT-treated normal skin mounts a more coordinated repair response than tumours. Cell-cell communication of death signals from directly irradiated, migrating cells, may explain why tumours are less resistant to high dose MRT than normal tissue.

Radiation film dosimetry process using the RIT 113 v.4 dosimetry software and the film digitizer VXR-l2plus was used to evaluate the accuracy of electron dose calculations of the RAHD radiation therapy treatment planning system at Samaritan Regional Cancer Center. Kodak Ready-Pack EDR-2 film is recommended for dose distribution analysis in clinically practical dose ranges. The pencil-beam algorithm has a limitation for calculating dose in the penumbra region and in the tail region where the dose falls off. / Graduation date: 2005

Graduation date: 2003

Graduation date: 1998

Since the beginning of space exploration in last century, several kinds of devices from passive and active dosimeters to radiation environment monitors have been used to measure radiation levels onboard different space crafts and shuttles allowing the space community to identify and quantify space radiation. The recent construction of several laboratories on the International Space Station (ISS) has confirmed that prolonged duration space missions are now becoming standard practice and as such, the need to better understand the potential risk of space radiation to Astronaut’s health, has become a priority for long mission planner. The complex internal radiation environment created within the ISS is due to high-energy particle interactions within the ISS shielded environment. As a result, a large number of secondary particles, that pose specific health risks, are created. Neutrons are one important component of this mixed radiation field due to their high LET. Therefore, the assessment of the neutron dose contribution has become an important part of the safety and monitoring program onboard the ISS. The need to determine whether neutron dose measured externally to the human body give an accurate and conservative estimate of the dose received internally is of paramount importance for long term manned space missions. This thesis presents a part of an ongoing large research program on radiation monitoring on ISS called Matroshka-R Project that was established to analyze the radiation exposure levels onboard the ISS using different radiation instruments and a spherical phantom to simulate human body. Monte Carlo transport code was used to simulate the interaction of high energy protons and neutrons with the spherical phantom currently onboard ISS. A Monte Carlo model of the phantom has been built, and it consists of seven spherical layers presenting different depths of the simulated tissue. The phantom has been exposed to individual proton energies and to a spectrum of neutrons. The flux of the created neutrons inside the phantom has been calculated. The internal to external neutron flux ratio was calculated and compared to the experimental data, recently, measured on three separate expeditions of the ISS. The results from the calculations showed that the value of the neutron fluxes inside and outside the phantom is different from the data recently measured with bubble detectors. / UOIT

Photodynamic Therapy (PDT) has proven to be a minimally invasive alternative treatment option for various conditions including cancer. The treatment efficacy of deep-seated tumours with PDT is variable, compared to the treatment of tissue surfaces such as the skin and esophagus. This is partly due to inadequate monitoring of the three interrelated treatment parameters: treatment light, photosensitizer and tissue oxygenation. This thesis presents the development of a system for explicit dosimetry of PDT treatment light and tissue oxygenation using multi-sensor fiber optic probes for spatially resolved parameter measurements. The system uses embedded fluorescent sensors for treatment light quantification. Tissue oxygenation measurement is accomplished using frequency domain techniques with embedded phosphorescent metalloporphyrin compounds as sensors.