The Influence of Normal Tissue Objective in the Treatment of Prostate Cancer.

PURPOSE: The normal tissue objective (NTO) is a tool used in inverse-planned intensity-modulated radiation therapy to reduce dose spreading to the surrounding tissues. Only a few studies in the present literature are dedicated to understanding the influence of the NTO in radiation therapy planning in patients with prostate cancer or its consequences in the reduction of the dose in the surrounding healthy tissues. MATERIAL AND METHODS: Our sample consists of 25 patients submitted to different treatment doses. Averages of plans with and without the NTO were obtained from the dose-volume histogram, and behaviours, comparisons, and quality were assessed considering homogeneity, conformity, and radiation plan indexes. RESULTS: We were not able to find significant differences in the conformity index, homogeneity index, and radiation planning index between groups with and without the NTO or between treatment times. We observed a small advantage in NTO plans regarding hot spots in the central region of the planning target volume. CONCLUSION: The NTO is an important tool used in the optimization of plans; however, possibly due to the anatomical location of the prostate, we failed to find a significant contribution of its use in the treatment of prostate cancer. Further studies, using a larger sample and different NTO parameters, are needed to confirm our results.

A Kindler syndrome-associated squamous cell carcinoma treated with radiotherapy.

Kindler syndrome1, 2 is a genetic disorder mainly characterized by increased skin fragility and photosensitivity,3, 4 making the use of treatments based on radiation difficult or even prohibited. Thus, cases reporting Kindler syndrome patients treated with radiotherapy are rare. In this study, we report clinical outcomes and care provided for a rare case of a Kindler syndrome patient submitted to radiotherapy. Diagnosed with squamous cell carcinoma involving the buccal mucosa, the patient was exclusively treated with radiotherapy, with 70 Gy delivered on the PTV with the Volumetric Modulated Arc technique. The patient's reaction regarding control of the lesion is relevant compared to patients not affected by the syndrome. We noticed acute reactions of the skin and buccal mucosa after few radiotherapy sessions, followed by a fast reduction in the tumor volume. The efficacy of radiotherapy along with multidisciplinary actions allowed treatment continuity, leading to a complete control of the lesion and life quality improvement and showed that the use of radiotherapy on Kindler syndrome patients is possible.

Comparação dosimétricas entre técnicas de irradiação de plastrão mamário / Dosimetric comparison between breast plastron irradiation techniques

"Existem diversas técnicas de tratamento propostas para tratamento de plastrão mamário. Neste trabalho efetuamos a dosimetria das técnicas mais utilizadas no Serviço de Radioterapia do Instituto Nacional de Câncer (INCA), que são a irradiação com campos tangentes de fótons em acelerador linear de 6MV e a irradiação com campos diretos de feixes de elétrons de 6MeV ou 9MeV angulados em 30º. Efetuamos também a dosimetria para uma configuração de Braquiterapia de contato com uma placa de Freiburg que pode tornar-se uma opção em casos especiais. As dosimetrias foram realizadas com filmes radiocrômicos posicionados a um cm de profundidade. Para os três casos apresentamos os resultados das medições e discutimos a distribuição de dose e, por conseqüência, a viabilidade e aplicabilidade destas técnicas. A técnica com tangentes de fótons apresentou boa cobertura e homogeneidade, o mesmo podendo ser dito do campo direto de elétrons com 9MeV apesar de discreta subdosagem na porção distal do campo. Já o feixe com 6MeV, apresentou uma subdosagem grande nessa mesma porção distal, sendo desaconselhado seu uso. A análise da proposta de Braquiterapia de contato mostrou ser um tratamento que apresenta excelente cobertura e uniformidade de dose na profundidade, porém com um alto gradiente de dose na pele para atingir a dose prescrita a 1 cm. Concluímos, portanto, que deve ser reservado a casos clínicos especiais."(AU)

There are several treatment techniques proposed for the treatment of breast plastron. In this work we perform the dosimetry of the most used techniques in the Radiotherapy Service of the National Cancer Institute (INCA), which are irradiation with tangent photon fields in a 6MV linear accelerator and irradiation with direct beam fields.