RESUMO
Intensity modulated radiation therapy (IMRT) allows physicians to deliver higher conformal doses to the tumour, while avoiding adjacent structures. As a result the probability of tumour control is higher and toxicity may be reduced. However, implementation of IMRT is highly complex and requires a rigorous quality assurance (QA) program both before and during treatment. The present article describes the process of implementing IMRT for localized prostate cancer in a radiation therapy department. In our experience, IMRT implementation requires careful planning due to the need to simultaneously implement specialized software, multifaceted QA programs, and training of the multidisciplinary team. Establishing standardized protocols and ensuring close collaboration between a multidisciplinary team is challenging but essential.
RESUMO
Absorbed dose and transmission factors were determined for 6 MV X-ray fields applied in four conventional external radiation treatments where protection blocks are used to shield organs at risk. Studied treatments are: head and neck (cancer of the larynx), breast (breast cancer), brain (brain tumours) and pelvis (cervix-uterine cancer). Experimental determinations were made using ionization chambers and thermoluminescent dosimeters, at different locations in phantoms, for blocked and unblocked fields. Calculated absorbed doses, using the treatment planning system and Clarkson method, were compared to those measured. Measured transmission factor values ranged from 5% to 18%. It was found that the planning treatment system may underestimate the absorbed dose under the blocks, up to 35%.
Assuntos
Neoplasias/radioterapia , Proteção Radiológica/instrumentação , Radioterapia de Alta Energia , Absorção , Neoplasias da Mama/radioterapia , Irradiação Craniana , Relação Dose-Resposta à Radiação , Feminino , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Neoplasias Laríngeas/radioterapia , Masculino , Aceleradores de Partículas , Neoplasias Pélvicas/radioterapia , Lesões por Radiação/prevenção & controle , Radiometria/métodos , Dosagem RadioterapêuticaRESUMO
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Absorbed dose and transmission factors were determinedfor 6 MV X-ray fields applied in four conventionalexternal radiation treatments where protectionblocks are used to shield organs at risk. Studiedtreatments are: head and neck (cancer of the larynx),breast (breast cancer), brain (brain tumours) andpelvis (cervix-uterine cancer). Experimental determinationswere made using ionization chambers andthermoluminescent dosimeters, at different locationsin phantoms, for blocked and unblocked fields.Calculated absorbed doses, using the treatmentplanning system and Clarkson method, were comparedto those measured. Measured transmissionfactor values ranged from 5% to 18%. It was foundthat the planning treatment system may underestimatethe absorbed dose under the blocks, up to 35%
