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Total body irradiation is the irradiation of the entire patient as a conditioning for bone marrow transplants. The conditioning process involves destroying the bone marrow allowing for repopulation of the donor bone marrow cells, suppression of the immune system to allow stop graft rejection, and to eliminate the cancer cell population within the patient. Studies have been done demonstrating the importance of TBI conditioning for BMT5. A range of TBI treatment techniques exist, this department uses a bi-lateral technique which requires bolus packed around the patient to simplify the geometry of the treatment. This investigation will focus on one technique which involves using a translating bed. This technique effectively scans a radiation beam over the patient as the bed moves through the beam. Other investigations on translating beds concentrated on varying the scan speed to achieve a dose uniformity to within ±5%. The recommendations quote a dose uniformity of +5% and -10% as acceptable⁹. The dose uniformity in these investigations was along the midline in the longitudinal direction only. This investigation varied field size to achieve dose uniformity to within ±2.5% along the midline of an anthropomorphic phantom. The goal was to determine if a dynamic multi-leaf collimator could be used to give a uniform in the transverse direction as well as the longitudinal direction. An advantage of utilizing the DMLC for this treatment is the ability to shield organs at risk, i.e. lungs and kidneys, without requiring resources to produce shielding blocks14. Gafchromic-EBT film18 was used as a dosimeter but gave unreliable results due to the lack of film scanning equipment with an appropriate sensitivity for reading the dose to the film. Scans were simulated using Xio treatment planning software. The results from the simulations gave a more reliable indication of the absorbed dose to the midline of the phantom. The disadvantage of this varying field size technique was the time and complexity involved in creating a treatment plan. Within the Xio software exists a limit on the number of beams allowed to be applied in a single plan. There is a maximum of 99 beams allowed which is not enough for complete coverage of a patient. A way around this is to increase the field sizes and decrease the scan speed. This option was not investigated. The advantage of this technique was the increased dose uniformity (±2.5%) in comparison to the varying scan speed techniques (±5%). This technique also allows the patient to be unencumbered during the treatment making the process more comfortable for them.

Na técnica de tratamento de irradiação de corpo total, como o próprio nome diz, a radiação atinge o corpo todo do paciente com uma dose uniforme. É uma das principais vias de tratamento interdisciplinar de neoplasias malignas, predominantemente doenças hematopoiéticas. Devido à complexidade da anatomia do corpo, essa técnica apresenta dificuldades na obtenção da distribuição de dose uniforme, além da atenção especial ao pulmão, por conta da sua heterogeneidade tecidual. Assim, o objetivo deste trabalho consiste em realizar estudos dosimétricos para irradiação de corpo total, possibilitando o desenvolvimento de novos procedimentos que auxiliem no planejamento da técnica durante a rotina clínica, com o intuito de aumentar a eficácia desse tipo de tratamento. No presente trabalho, realizaram-se medidas experimentais de dose de corpo total, utilizando câmara de ionização em objeto simulador antropomórfico. Visto que o método de Monte Carlo é considerado um padrão ouro na forma de validação para os dados obtidos experimentalmente, realizou-se cálculo de dose no objeto simulador antropomórfico utilizando o código MCNP6 e o software AMIGOBrachy. Entre as etapas envolvidas, iniciou-se com a verificação da equivalência entre aceleradores a partir de um espaço de fase. O andamento do trabalho ocorreu com a substituição do espaço de fase por um modelo de fonte virtual para campos alargados: 40 x 40 cm2 e 40 x 40 cm2 rotacionado 45°, este utilizado na técnica de irradiação de corpo total. Dando continuidade, determinou-se uma configuração geométrica para a câmara de ionização, de forma a melhor reproduzir a dose na pele obtida experimentalmente. Foram feitas comparações entre dados experimentais e cálculos para irradiação de phantom antropomórfico, observando-se uma homogeneidade na distribuição de dose durante essa reprodução de tratamento. Por fim, foi feita a comparação de cálculos de dose total com e sem blindagem para pulmão, e os resultados se mostraram dentro do limite aceitável de dose de 8 a 10 Gy. A metodologia de cálculo desenvolvida neste trabalho com o uso do método de Monte Carlo, juntamente com o software AMIGOBrachy, foram úteis para demonstrar a adequação do procedimento de irradiação de corpo total em termos dosimétricos. Além disso, esta metodologia mostrou-se ser uma ferramenta de cálculo de dose muito importante para estudos futuros que visem aumento da eficácia para esta modalidade de tratamento, pois permite, através de simulações, estimar distribuições de dose de forma detalhada e precisa, auxiliando no planejamento do tratamento de irradiação de corpo total. / In the total body irradiation technique, as the name says, the radiation hits the whole body of the patient as an uniform dose. It is one of the main ways of interdisciplinary treatment of malignant neoplasms, mainly hematopoietic diseases. Due the complexity of the human anatomy, this technique presents difficulties in obtaining an uniform dose distribution, besides special attention to lungs due its tissue heterogeneity. Therefore, the objective of this work is to perform dosimetric studies for total body irradiation, allowing the development of new procedures to help the technique planning phase during the clinical routine, aiming to increase the efficacy of this kind of treatment. In this work, experimental dose measurements for total body were made using ionization chamber on an anthropomorphic object simulator. Since Monte Carlo method is considered a gold standard as validation for the experimentally data obtained, a dose calculation in the anthropomorphic object simulator was done using the code MCNP6 and the AMIGOBrachy software. Among the involved steps, the verification of the equivalence between accelerators from a phase space was done. The work progress occurred with the substitution of phase space for a virtual source model for the large fields: 40 x 40 cm2 and 40 x 40 cm2 rotated 45°, the later used in the technique for total body irradiation. Following next, a geometric configuration for the ionization chamber was determined to better reproduce the experimental dose on the skin. Anthropomorphic phantom irradiation comparisons were made between experimental data and calculations, observing a homogeneity in the dose distribution during this treatment reproduction. Lastly, the comparison of total dose calculation with and without lung shielding has been done and the results showed to be inside the acceptable dose limit of 8 to 10 Gy. The calculation methodology developed in this work using the Monte Carlo method, along with the AMIGOBrachy software, were useful to demonstrate the procedure adequacy for total body irradiation in dosimetry terms. Besides that, this methodology showed itself as very important dose calculation tool for future studies which aim to increase the efficacy in this treatment procedure because it allows, through simulations, to estimate dose distribution in a more detailed and accurate way, helping to plan the total body irradiation treatment.

Ao implementar uma técnica de tratamento, as características do feixe nas condições de irradiação precisam ser bem conhecidas e estudadas. Cada um dos parâmetros utilizados para cálculo de dose deve ser medido e validado antes da utilização dos mesmos na rotina clínica. Isso se torna ainda mais necessário quando se tratam de técnicas especiais. Neste trabalho estão descritos todos os parâmetros e medidas necessárias para a implementação da irradiação de corpo inteiro numa instalação projetada para tratamentos convencionais, e que faz uso de geometrias não convencionais para gerar os tamanhos de campos alargados. Além disso, são apresentados os dados de comissionamento desta modalidade no Hospital das Clínicas de São Paulo utilizando a comparação de três tipos de detectores para medidas de dose de entrada durante tratamentos de irradiação de corpo inteiro. / Before implementing a treatment technique, the characteristics of the beam under irradiation conditions must be well acknowledged and studied. Each one of the parameters used to calculate the dose has to be measured and validated before its utilization in clinical practice. This is particularly necessary when dealing with special techniques. In this work, all necessary parameters and measurements are described for the total body irradiation implementation in facilities designed for conventional treatments that make use of unconventional geometries to generate desired enlarged field sizes. Furthermore, this work presents commissioning data of this modality at Hospital das Clínicas of São Paulo using comparison of three detectors types for measurements of entrance dose during total body irradiation treatment.

Os resultados esperados em Radioterapia requerem o controle da qualidade dos procedimentos executados, existindo a necessidade de avaliar-se a dose administrada aos pacientes e sendo recomendado que a diferença percentual entre as doses prescrita e administrada esteja entre -5% e +7%, conforme a Comissão Internacional sobre Unidades e Medidas em Radiação (ICRU). Especificamente em tratamentos de irradiação de corpo inteiro (TBI, do inglês Total Body Irradiation), que emprega distâncias fonte-superfície extensas e campos largos de radiação, apresentando um grau de complexidade elevada quando comparada com os procedimentos convencionais, não há um protocolo bem estabelecido para o cálculo da dose absorvida. Considerando-se, por outro lado, os efeitos colaterais severos associados ao tratamento, TBI requer um controle rigoroso das doses administradas ao paciente, fazendo com que um programa de verificação do tratamento através de dosimetria in vivo seja imprescindível. O presente trabalho apresenta um estudo dos parâmetros dosimétricos, para campos convencionais e de irradiação de corpo inteiro, como parte de um programa de controle da qualidade em Radioterapia. Os parâmetros dosimétricos foram determinados utilizando-se dosímetros termoluminescentes, câmara de ionização e dosímetro semicondutor. Avaliaram-se as correções necessárias para o uso dos parâmetros dosimétricos, obtidos em condições convencionais, nos tratamentos de irradiação de corpo inteiro, apresentado-se, ainda, uma metodologia de dosimetria in vivo para tratamentos de TBI. Os resultados obtidos permitem concluir que os parâmetros dosimétricos utilizados em TBI devem ser obtidos nas condições próprias desse tipo de técnica, não devendo ser adaptados de condições convencionais, e que a metodologia de dosimetria de entrada é adequada para avaliação das doses nessa técnica de tratamento. / The expected outcomes in Radiotherapy require a strict quality control program to be performed in order to evaluate the doses delivered to patients. Accordingly to the International Commission on Radiation Units and Measurements (ICRU) the possible discrepancies between prescribed and delivered doses to patients must be in a range of -5% and +7%. Treatments of total body irradiation (TBI) use large source-surface distances and broad radiation fields, showing high complexity when compared to conventional procedures and do not present a well-established protocol for the calculation of the absorbed dose. On the other hand, considering, the severe collateral effects associated to this treatment, TBI requires a rigorous control of the doses administrated to the patient and a program of verification of the treatment through in vivo dosimetry is paramount. This work presents a study of dosimetric parameters for both conventional and total body irradiation treatments as part of a quality control program in Radiotherapy. The dosimetric parameters had been determined using termoluminescente dosimetry, ionization chamber, and semiconductor dosimeters. Possible corrections for the use of the conventional conditions-obtained parameters in total body irradiation were evaluated. An in vivo dosimetry methodology had been also studied to be applied to TBI treatments. The obtained results leads to the conclusions that TBI dosimetric parameters must be obtained under proper irradiation conditions and should not be adapted from conventional conditions and that entrance dosimetry is an adequate technique to evaluate delivered doses in TBI.

Ao implementar uma técnica de tratamento, as características do feixe nas condições de irradiação precisam ser bem conhecidas e estudadas. Cada um dos parâmetros utilizados para cálculo de dose deve ser medido e validado antes da utilização dos mesmos na rotina clínica. Isso se torna ainda mais necessário quando se tratam de técnicas especiais. Neste trabalho estão descritos todos os parâmetros e medidas necessárias para a implementação da irradiação de corpo inteiro numa instalação projetada para tratamentos convencionais, e que faz uso de geometrias não convencionais para gerar os tamanhos de campos alargados. Além disso, são apresentados os dados de comissionamento desta modalidade no Hospital das Clínicas de São Paulo utilizando a comparação de três tipos de detectores para medidas de dose de entrada durante tratamentos de irradiação de corpo inteiro. / Before implementing a treatment technique, the characteristics of the beam under irradiation conditions must be well acknowledged and studied. Each one of the parameters used to calculate the dose has to be measured and validated before its utilization in clinical practice. This is particularly necessary when dealing with special techniques. In this work, all necessary parameters and measurements are described for the total body irradiation implementation in facilities designed for conventional treatments that make use of unconventional geometries to generate desired enlarged field sizes. Furthermore, this work presents commissioning data of this modality at Hospital das Clínicas of São Paulo using comparison of three detectors types for measurements of entrance dose during total body irradiation treatment.

Total body irradiation is the irradiation of the entire patient as a conditioning for bone marrow transplants. The conditioning process involves destroying the bone marrow allowing for repopulation of the donor bone marrow cells, suppression of the immune system to allow stop graft rejection, and to eliminate the cancer cell population within the patient. Studies have been done demonstrating the importance of TBI conditioning for BMT5. A range of TBI treatment techniques exist, this department uses a bi-lateral technique which requires bolus packed around the patient to simplify the geometry of the treatment. This investigation will focus on one technique which involves using a translating bed. This technique effectively scans a radiation beam over the patient as the bed moves through the beam. Other investigations on translating beds concentrated on varying the scan speed to achieve a dose uniformity to within ±5%. The recommendations quote a dose uniformity of +5% and -10% as acceptable⁹. The dose uniformity in these investigations was along the midline in the longitudinal direction only. This investigation varied field size to achieve dose uniformity to within ±2.5% along the midline of an anthropomorphic phantom. The goal was to determine if a dynamic multi-leaf collimator could be used to give a uniform in the transverse direction as well as the longitudinal direction. An advantage of utilizing the DMLC for this treatment is the ability to shield organs at risk, i.e. lungs and kidneys, without requiring resources to produce shielding blocks14. Gafchromic-EBT film18 was used as a dosimeter but gave unreliable results due to the lack of film scanning equipment with an appropriate sensitivity for reading the dose to the film. Scans were simulated using Xio treatment planning software. The results from the simulations gave a more reliable indication of the absorbed dose to the midline of the phantom. The disadvantage of this varying field size technique was the time and complexity involved in creating a treatment plan. Within the Xio software exists a limit on the number of beams allowed to be applied in a single plan. There is a maximum of 99 beams allowed which is not enough for complete coverage of a patient. A way around this is to increase the field sizes and decrease the scan speed. This option was not investigated. The advantage of this technique was the increased dose uniformity (±2.5%) in comparison to the varying scan speed techniques (±5%). This technique also allows the patient to be unencumbered during the treatment making the process more comfortable for them.

Os resultados esperados em Radioterapia requerem o controle da qualidade dos procedimentos executados, existindo a necessidade de avaliar-se a dose administrada aos pacientes e sendo recomendado que a diferença percentual entre as doses prescrita e administrada esteja entre -5% e +7%, conforme a Comissão Internacional sobre Unidades e Medidas em Radiação (ICRU). Especificamente em tratamentos de irradiação de corpo inteiro (TBI, do inglês Total Body Irradiation), que emprega distâncias fonte-superfície extensas e campos largos de radiação, apresentando um grau de complexidade elevada quando comparada com os procedimentos convencionais, não há um protocolo bem estabelecido para o cálculo da dose absorvida. Considerando-se, por outro lado, os efeitos colaterais severos associados ao tratamento, TBI requer um controle rigoroso das doses administradas ao paciente, fazendo com que um programa de verificação do tratamento através de dosimetria in vivo seja imprescindível. O presente trabalho apresenta um estudo dos parâmetros dosimétricos, para campos convencionais e de irradiação de corpo inteiro, como parte de um programa de controle da qualidade em Radioterapia. Os parâmetros dosimétricos foram determinados utilizando-se dosímetros termoluminescentes, câmara de ionização e dosímetro semicondutor. Avaliaram-se as correções necessárias para o uso dos parâmetros dosimétricos, obtidos em condições convencionais, nos tratamentos de irradiação de corpo inteiro, apresentado-se, ainda, uma metodologia de dosimetria in vivo para tratamentos de TBI. Os resultados obtidos permitem concluir que os parâmetros dosimétricos utilizados em TBI devem ser obtidos nas condições próprias desse tipo de técnica, não devendo ser adaptados de condições convencionais, e que a metodologia de dosimetria de entrada é adequada para avaliação das doses nessa técnica de tratamento. / The expected outcomes in Radiotherapy require a strict quality control program to be performed in order to evaluate the doses delivered to patients. Accordingly to the International Commission on Radiation Units and Measurements (ICRU) the possible discrepancies between prescribed and delivered doses to patients must be in a range of -5% and +7%. Treatments of total body irradiation (TBI) use large source-surface distances and broad radiation fields, showing high complexity when compared to conventional procedures and do not present a well-established protocol for the calculation of the absorbed dose. On the other hand, considering, the severe collateral effects associated to this treatment, TBI requires a rigorous control of the doses administrated to the patient and a program of verification of the treatment through in vivo dosimetry is paramount. This work presents a study of dosimetric parameters for both conventional and total body irradiation treatments as part of a quality control program in Radiotherapy. The dosimetric parameters had been determined using termoluminescente dosimetry, ionization chamber, and semiconductor dosimeters. Possible corrections for the use of the conventional conditions-obtained parameters in total body irradiation were evaluated. An in vivo dosimetry methodology had been also studied to be applied to TBI treatments. The obtained results leads to the conclusions that TBI dosimetric parameters must be obtained under proper irradiation conditions and should not be adapted from conventional conditions and that entrance dosimetry is an adequate technique to evaluate delivered doses in TBI.