ABSTRACT
Objective To study the accuracy of SentinelTM system for patient setup using rigid-body phantom.Methods A 002LFC IMRT phantom was placed on Elekta HexaPODTM 6-degree couch using tattoo and the laser in the treatment room.When a well-know shift (3 directions) and rotation (3 positions) was moved,CBCT and SentinelTM system were scanned respectively,and the measuring errors of six dimensions were recorded.The absolute differences between applied and measured errors were compared and paired t-test.Results Total 15 well-know shifts were investigated.The SentinelTM system was very good stability and the largest absolute difference only 0.9 mm (z direction) and 0.2° (arbitrary direction).At the same time,a good conformance between SentinelTM system and CBCT was displayed because the largest absolute difference between applied and measuring error was less than 0.9 mm (z direction) and 0.2° (arbitrary direction).Conclusions SentinelTM system is fast,simple,non-invasive and seems to be reliable in detecting patient setup errors.It maybe hold potential to ensure precise patient positioning with reduced CBCT frequency in tumor locations with fixed relation to surface structures.