Patient Setup Optimization for External Conformal Radiotherapy

The aim of conformal radiotherapy is to deliver precisely a specific dose of radiation to a planning target volume, concurrently radiating as little healthy tissue and organs as possible. This can be accomplished only with the accurate positioning of the patient with respect to the radiotherapy system. In this paper, we describe a system to achieve a higher overall accuracy in the delivery of a prostatic radiation boost for treatment of carcinoma of the prostate. The system is based on the use of ultrasound images for measuring the actual position of the patient's prostate just before the radiation. Since these images are registered with pretreatment computed tomography or magnetic resonance imaging, the position and orientation of the planning target volume are computed with respect to the radiotherapy system and can be corrected as needed. This system is under clinical evaluation.