Sparing of Organs at Risk in High Dose Rate Brachytherapy

Cervix carcinoma is a common malignancy. Radiation therapy still remains a major treatment for patients with carcinoma cervix. Conventional treatment with radiation therapy includes a combination of external beam radiation therapy and intracavitary treatment. Low dose rate intracavitary brachytherapy treatment is already well studied. But high dose rate brachytherapy is a relatively new alternative. In brachytherapy, major developments have been made in the integration of 3D imaging and computerized 3D treatment planning. Medical imaging improvements allowed for better definition of tumoral volumes and organs at risk. The GYN GEC-ESTRO published recommendations on the 3D imaging for better characterization of these volumes. Improvements in CT-SCan and lately in RMN had lead to a better definition of volums of interest (tumor and his extensions and organs at risk : bladder, rectum, sigmoidis, small bowels). RMN is the imaging standard in the evaluation of tumoral extension in cervix cancer. However its use is not easy in many brachytherapy departments. This study will evaluate the feasibility and sparing of organs at risk for high dose rate brachytherapy if volume delineation is done at each of the two sessions performed with 3D RMN.