Sparing of Organs at Risk in High Dose Rate Brachytherapy

Overview

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.

After 60 Gy are delivered with Intensity Modulated Radiation Therapy (IMRT), the brachytherapy in high dose rate will deliver 15 Gy to the CTVhr (high risk CTV) in two sessions. A clinical examination and an RMN are performed at the end of the external radiation to evaluate the residual tumoral volume. Two HDR brachytherapy sessions are then performed. During the first session, a CT-Scan and an RMN will be performed after the fletcher application. A second CT-Scan will be performed during the second treatment session to create new volumes and to improve organs at risk sparing.

Conditions