002LFC调强放疗模体评价SentinelTM监控与摆位验证系统的精确性研究

A 002LFC intensity-modulated radiotherapy （IMRT） phantom evalution of SentinelTM system for patient set-up verification in radiotherapy

目的 利用刚性调强放疗（IMRT）模体评价SentinelTM系统辅助摆位的精确性.方法 002LFC IMRT模体激光线标记摆位后,利用医科达HexaPODTM六维床移动给定一个已知标准误差,分别做SentinelTM和XⅥTM CBCT扫描,记录6个方位（x、y、z方向平移和旋转）的测量误差.采用配对t检验比较两者测量误差与已知误差差值绝对值差异.结果 SentinelTM系统具有较高稳定性,最大平移（z方向）、旋转（任意方向）误差差值绝对值分别为0.9 mm、0.2.；SentinelTM系统与CBCT之间具有较高符合性,两者间测量误差与已知标准误差差值绝对值分别＜0.9 mm（z轴方向）、0.2.（任意方向）.结论 SentinelTM监控与摆位验证系统是一种快速、方便、无创、无辐射的摆位辅助装置,且稳定性好.在头颈部等肿瘤相对位置固定患者中可以配合CBCT应用,以减少多次CBCT扫描所带来的额外照射.

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.