Optical imaging is becoming more prevalent in image guided radiotherapy as a complementary technology to traditional ionizing radiation based modalities. We present a novel structured light based device that can capture a patient's body surface topology with a large field of view and high spatial and temporal resolution. The system is composed of three cross-calibrated sensor heads that enable 'wrap around' imaging previously unavailable with similar line of sight optical techniques. The system has been installed in a treatment bunker at the Christie Hospital alongside an Elekta linear accelerator equipped with cone beam CT (CBCT) on-board imaging. In this paper we describe the system, focussing on the methodologies required to create a robust and practical device. We show examples of measurements made to ascertain its repeatability and accuracy, and present some initial experiences in using the device for pre-treatment patient set-up.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.