High Dose Three-Dimensional Conformal Boost Using the Real-Time Tumor Tracking Radiotherapy System in Cervical Cancer Patients Unable to Receive Intracavitary Brachytherapy

PURPOSE: The purpose of this study is to evaluate the clinical results of treatment with a high dose of 3-dimensional conformal boost (3DCB) using a real-time tracking radiation therapy (RTRT) system in cervical cancer patients. MATERIALS AND METHODS: Between January 2001 and December 2004, 10 patients with cervical cancer were treated with a high dose 3DCB using RTRT system. Nine patients received whole pelvis radiation therapy (RT) with a median dose of 50 Gy (range, 40-50 Gy) before the 3DCB. The median dose of the 3DCB was 30 Gy (range, 25-30 Gy). Eight patients received the 3DCB twice a week with a daily fraction of 5 Gy. The determined endpoints were tumor response, overall survival, local failure free survival, and distant metastasis free survival. The duration of survival was calculated from the time of the start of radiotherapy. RESULTS: All patients were alive at the time of analysis and the median follow-up was 17.6 months (range, 4.9-27.3 months). Complete response was achieved in nine patients and one patient had a partial response. The 1- and 2-year local failure free survival was 78.8% and 54%, respectively. The 1- and 2-year distant metastasis free survival was 90% and 72%, respectively. Late toxicity of a grade 2 rectal hemorrhage was seen in one patient. A subcutaneous abscess was encountered in one patient. CONCLUSION: The use of the high dose 3DCB in the treatment of cervical cancer is safe and feasible where intracavitary brachytherapy (ICBT) is unable to be performed. The escalation of the 3DCB dose is currently under evaluation.

Análise comparativa dos histogramas de dose e volume entre planejamentos tridimensionais conformados e convencionais não conformados na radioterapia do câncer de próstata / Comparative analysis of dose-volume histograms between 3D conformal and conventional non-conformal radiotherapy plannings for prostate cancer

OBJETIVO: Analisar, comparativamente, doses de radiação em volumes alvos e órgãos de risco entre planejamentosconformados e não conformados em pacientes com câncer de próstata. MATERIAIS E MÉTODOS: No presente trabalho foram analisados planejamentos de 40 pacientes portadores de câncer de próstata. Foram realizados planejamentos conformados, não conformados isocêntricos e não conformados utilizando a distância fonte-superfície, simulados para cada caso, para comparação das doses em volumes alvos e órgãos de risco. Para a comparação foram analisados os histogramas de dose e volume para volumes alvos e órgãos de risco. RESULTADOS: As medianas das doses foram significativamente menores no planejamento conformado analisando-se os seguintes volumes no reto: 25%, 40% e 60%. As medianas das doses foram significativamente menores no planejamento conformado analisando-se os seguintes volumes na bexiga: 30%e 60%. As doses medianas foram significativamente menores no planejamento conformado analisando-seas articulações coxofemorais direita e esquerda. As doses máximas, médias e medianas no volume alvo clínico e no volume alvo planejado foram significativamente maiores no planejamento conformado. CONCLUSÃO:O presente estudo demonstrou que por meio do planejamento conformado em pacientes com câncer de próstata é possível entregar doses maiores no volume alvo e doses menores em órgãos de risco.

OBJECTIVE: The present study was aimed at comparing conformal and non-conformal radiotherapy plans designed for patients with prostate cancer, by analyzing radiation doses in target volumes and organs at risk. MATERIALS AND METHODS: Radiotherapy plans for 40 patients with prostate cancer were analyzed. Conformal, conformal isocentric and non-conformal plans utilizing the source-surface distance were simulated for each of the patients for comparison of radiation dose in target volumes and organs at risk. For comparison purposes, dose-volume histograms for target volumes and organs at risk were analyzed. RESULTS: Median doses were significantly lower in the conformal planning, with 25%, 40% and 60% volumes in the rectum and 30% and 60% in the bladder. The median doses were significantly lower in the conformal planning analyzing the right and left coxofemoral joints. Maximum, mean and median doses in the clinical target volume and in the planned target volume were significantly higher in the conformal planning. CONCLUSION: The present study has demonstrated that the conformal radiotherapy planning for prostate cancer allows the delivery of higher doses to the target volume and lower doses to adjacent healthy tissues.