Prostate cancer is the most frequent cancer in men. Radiotherapy is one of the reference treatments for localized prostate cancer. Prostate was initially thought to be a non-moving target, but the newest reports have raised the contrary as evidence. Image-guided radiotherapy (IGRT) is a current standard treatment for localized prostate cancer which enables to take into account interfractional prostate motion before treatment.~The Calypso® System (Varian Medical Systems, Inc., Palo Alto, CA) is a recent technology using electromagnetic transponders implanted within the prostate. It is a real-time target tracking system that takes into account both inter- and intrafractional target motion. So the exact position and movement of the prostate can be determined during radiation therapy treatment.~As Planned Target Volume (PTV) margins integrate set-up margins and the management of organ motion, margin reduction can reasonably be considered in case of target motion management improvement.~To date, no prospective randomized clinical data is available using this technique for the treatment of low- or intermediate-risk prostate cancer patients with modern standard fractionation radiotherapy and image guidance.~The aim of this study is to assess pelvic late toxicity rate after intensity-modulated radiotherapy (IMRT) when using the Calypso® System with a reduction of treatment margins. In this randomized study, patients will receive IGRT treatment using the Calypso system or a conventional IGRT treatment.
The Calypso® System (Varian Medical Systems, Inc., Palo Alto, CA) is a recent technology using electromagnetic transponders implanted within the prostate. It is a real-time target tracking system that takes into account both inter- and intrafractional target motion. So the exact position and movement of the prostate can be determined during radiation therapy treatment.~The aim of this study is to assess pelvic late toxicity rate after intensity-modulated radiotherapy (IMRT) when using the Calypso® System with a reduction of treatment margins. In this randomized study, patients will receive IGRT treatment using the Calypso system or a conventional IGRT treatment.