Reducing radiation dose to pelvic small bowel in cervical cancer patients treated with Ir-192 intracavitary brachytherapy by using urinary bladder distension.

OBJECTIVES: Several techniques and devices have been used in an attempt to minimize radiation dose to gastrointestinal tract while giving pelvic radiation. We evaluated the effect of urinary bladder distension to displace pelvic small bowel out of intracavitary brachytherapy field to minimize radiation dose to small bowel in cervical cancer patients. MATERIAL AND METHOD: Eleven cervical cancer patients who received Ir-192 intracavitary brachytherapy with tandem and transverse ovoids were included in this study. Oral contrast material was used to visualize pelvic small bowel. Urinary bladder was distended by injection 125-200 ml. normal saline solution. Pelvic radiograph, anteroposterior and lateral view, was performed before and after bladder distention for brachytherapy treatment planning and comparing radiation dose at small bowel. RESULTS: The average maximum radiation dose at small bowel before and after bladder distension were 3123 cGy and 1998 cGy respectively. The summation of small bowel dose was reduced 54.17% (p = 0.002). CONCLUSION: Urinary bladder distension could effectively displace pelvic small bowel and reduce the radiation dose to small bowel from Ir-192 intracavitary brachytherapy in cervical cancer patients.

Braquiterapia de alta taxa de dose / High dose rate brachytherapy

A braquiterapia de alta taxa de dose utiliza fonte unica de '192 ANT. IND Ir' com atividade nominal inicial de 10Ci em equipamento com controle remoto. Esta tecnica permite que o tratamento seja realizado em regime ambulatorial, sem os inconvenientes da braquiterapia classica, como anestesia geral ou raquidiana, imobilizacao prolongada no leito e exposicao de pessoa a irradiacao. O servico de radioterapia possui cinco protocolos de tratamento em estudo: carcinoma de colo uterino, endometrio, pulmao, esofago e tumores do sistema nervoso central. Desde a instalacao do Micro Selectron HDR foram tratados 90 pacientes, com um total de 257 procedimentos. As aplicacoes sao semanais, perfazendo tres a quatro fracoes. Devido ao pouco tempo de atividade, os resultados sao preliminares, mas perfeitamente comparaveis aos primeiros meses dos tratamenos classicos. Nao tivemos nenhuma complicacao durante os procedimentos ou imediatamente apos. Muitos estudos devem ser realizados para se estabelecer criterios de dose, fracionamento e associacao ideais, a fim de se alcancar um alto nivel de taxa terapeutica.