Avaliação da distribuição da dose de radiação em aplicador de betaterapia: comparação com feixes clínicos de elétrons
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Data
2019-11-11
Autores
Santos, Bruno Gomes dos
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Universidade Estadual Paulista (Unesp)
Resumo
A radioterapia é a especialidade médica que utiliza feixes de radiações ionizantes para destruir
ou impedir a proliferação das células tumorais. No câncer, as células apresentam um
crescimento desordenado, agressivo e incontrolável, invadindo tecidos e órgãos. Para o
tratamento de lesões superficiais, utilizam-se feixes de radiação de baixa penetração no tecido
biológico, assim, a dose de radiação total será liberada em pequena profundidade, preservando
os tecidos saudáveis. Os queloides, mesmo não sendo tumores malignos, são caracterizados por
uma desordem do complexo sistema de cicatrização e reparo tecidual da pele após um trauma
ou excisão cirúrgica, causando um acumulo de colágeno na derme, resultando em uma cicatriz
elevada, que causa malefícios. O tratamento eletivo para queloide é a cirurgia com a remoção
da lesão, todavia, apresenta alta taxa de recidiva. A betaterapia e a terapia com feixes de elétrons
são técnicas de radioterapia usadas na prevenção da recidiva do queloide, e outras lesões
cutâneas. Neste estudo, avaliou-se o comportamento da dose de radiação emitida por ambas
técnicas, analisando a distribuição de dose na superfície e na profundidade do tecido irradiado
e comparando com dados obtidos da literatura. Os resultados apontaram que a curva de
atenuação da dose de radiação proveniente do aplicador de betaterapia de estrôncio-90 é mais
acentuada do que a dos feixes de elétrons de megavoltagem, indicando que os feixes de raios
beta são mais efetivos para tratamentos de lesões mais superficiais, enquanto os feixes de
elétrons são mais apropriados para terapia de lesões cutâneas mais profundas
Radiotherapy is the medical specialty that uses ionizing radiation beams to destroy or prevent the proliferation of tumor cells. In cancer, the cells show a disordered, aggressive and uncontrollable growth, invading tissues and organs. For the treatment of superficial lesions, low penetration radiation beams are used in the biological tissue, thus, the total radiation dose will be released in a small depth, preserving healthy tissues. Even though they are not malignant tumors, keloids are characterized by a disorder of the complex healing system and tissue repair of the skin following trauma or surgical excision, causing collagen accumulation in the dermis, resulting in a high scar that causes harm. The elective treatment for keloids is surgery with the removal of the lesion, however, it presents a high recurrence rate. Beta-therapy and electron beam therapy are radiotherapy techniques used to prevent keloid recurrence and other skin lesions. In this study, the behavior of the radiation dose emitted by both techniques was evaluated by analyzing the dose distribution on the surface and depth of the irradiated tissue and comparing it with data obtained from the literature. The results showed that the attenuation curve of the radiation dose from the strontium-90 beta-ray applicator is steeper than that of the megavoltage electron beams, indicating that beta-ray beams are more effective for treating superficial lesions, while electron beams are more appropriate for therapy of deeper skin lesions
Radiotherapy is the medical specialty that uses ionizing radiation beams to destroy or prevent the proliferation of tumor cells. In cancer, the cells show a disordered, aggressive and uncontrollable growth, invading tissues and organs. For the treatment of superficial lesions, low penetration radiation beams are used in the biological tissue, thus, the total radiation dose will be released in a small depth, preserving healthy tissues. Even though they are not malignant tumors, keloids are characterized by a disorder of the complex healing system and tissue repair of the skin following trauma or surgical excision, causing collagen accumulation in the dermis, resulting in a high scar that causes harm. The elective treatment for keloids is surgery with the removal of the lesion, however, it presents a high recurrence rate. Beta-therapy and electron beam therapy are radiotherapy techniques used to prevent keloid recurrence and other skin lesions. In this study, the behavior of the radiation dose emitted by both techniques was evaluated by analyzing the dose distribution on the surface and depth of the irradiated tissue and comparing it with data obtained from the literature. The results showed that the attenuation curve of the radiation dose from the strontium-90 beta-ray applicator is steeper than that of the megavoltage electron beams, indicating that beta-ray beams are more effective for treating superficial lesions, while electron beams are more appropriate for therapy of deeper skin lesions
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Palavras-chave
Radiotherapy, Dosimetry, Linear accelerator, Beta-therapy applicator, Keloid, Ionizing radiation, Dosimetria, Acelerador linear, Aplicador de betaterapia, Queloide, Radiações ionizantes, Radioterapia