A surface imaging system for setup verification of radiotherapy treatments in pelvic and thoracic regions.

In radiotherapy treatment, most of the setup verification systems, as portal imaging device or cone beam computed tomography (CBCT), use ionizing radiation. These systems give an additional dose of radiation to patients and this can be an issue for use on daily basis. A completely different approach is achieved by surface imaging systems which compare the external body surface acquired with an optical system with another of reference. The absence of any additional radiation exposure make surface systems an interesting solution for daily repositioning checks. The aim of this work is to investigate the performances of Sentinel, a laser/camera surface imaging system, when used on patients. The system accuracy was evaluated comparing registrations results from concurrent Sentinel and CBCT acquisitions of patients being treated in the thorax or pelvic regions. System employment conditions and patient setup procedures that provide more accurate results are also reported.