Delta4的临床应用研究

Clinical application of Delta4

目的通过两种调强放疗验证工具的分析比对，探讨一种全新三维验证工具临床应用的可行性。方法从接受调强放疗患者中随机抽取5例，分别在飞利浦Pinnacle 8．0D治疗计划系统中做MapCHECK Model 1175（Sun Nuclear，Melbourne，FL，USA）设计和Delta4（ScandiDos，Sweden）设计，然后分别在瓦里安Clinal23EX直线加速器上做剂量验证测量。计较Delta4和MapCHECK计划中相同剂量偏差（DD2％、DD3％、DD4％）和吻合距离（DTA2mm、DTA3rnm、DTA4mm）数值时的通过率差异。结果用MapCHECK Model 1175测量的剂量偏差为DD2％DTA2mm、DD3％DTA3mm、DD4％DTA4mm时总的平均通过率分别为84．7％、97．1％、99．3％；用Delta4测量的分别为86．2％、98．2％、99．6％；3组数据比较差异均有统计学意义（t=3．94，P=0．003；t=3．17，P=0．011；t=3．05，P=0．014）。MapCHECK的质量保证计划中把每个射野的大机架角度都要改为0°，而Deha4无任何改变。在测量过程中重力对多叶光栅叶片到到位精度影响、治疗床对剂量分布影响、地磁对剂量系统影响在Delta4测量中都可得到体现。结论Deha4是调强放疗非常理想的验证工具。

Objective To compare two verification tools for intensity modulated radiotherapy （IMRT） and to investigate the feasibility of a new three dimensitional verification tool. Methods Five patients receiving IMRT were randomly chosen for the quality assurance plans with MapCHECK Model 1175 （SunNuclear, Melbourne, FL,USA） and Delta4 （ScandiDos, Sweden） by using Philips Pinnacle 8. OD treatment planning system. Dose verification was measured with the Varian Clinical 23EX LA. Results The overall average percentages of pass points in DD2% DTA2 mm, DD3% DTA3 mm and DD4% DTA4 mm were 84.7%, 97.1% and 99.3% with MapCHECK Model 1175, 86.2%, 98.2% and 99.6% with Deha4 respectively. The differences were statisticically significant （ t =3.94, P =0. 003 ; t = 3.17, P = 0.011 ; t=3.05, P = 0. 014, respectively）. The gantry angle was changed to zero degree with MapCHECK, but not with Delta. The effects were embodied with Delta, such as the gravity on leaf position accuracy of MLC, the treatment table on dose distribution and the earth magnetism on dose system. Conclusion Delta4 is an ideal verification tool for intensity modulated radiotherapy.