摘要
目的:基于二维二极管阵列探测器模拟床面倾斜对放疗剂量验证通过率的影响。方法:选择调强放射治疗(IMRT)和三维适形放疗(3DCRT)计划患者各10例的剂量验证计划,在加速器治疗床用边缘充气袋以左右激光灯示值差模拟床面倾斜,倾斜幅度选择1、2、3、5、7、10 mm。选择Gamma(γ)分析法,(3%,3 mm)绝对剂量分析标准,记录计划和模拟实验结果,用配对t检验分析结果。结果:在无床面倾斜条件下,剂量验证通过率:IMRT为(96.10±1.65)%,3DCRT为(97.50±1.98)%。IMRT患者在倾斜7、10 mm的通过率分别为(86.50±5.95)%、(85.40±8.53)%,与无倾斜通过率比值分别为0.90±0.05和0.85±0.08;3DCRT患者在倾斜最大(10 mm)的通过率为(91.90±4.90)%,与无倾斜比值为0.94±0.05。与无倾斜对比,除了3DCRT在倾斜2 mm没有统计学意义(P=0.366),其余倾斜幅度差异均有统计学意义(P<0.05)。结论:床面倾斜对3DCRT剂量验证通过率影响较小;而IMRT通过率随床面倾斜幅度增大而减小,幅度较大,但变化幅度存在个体性差异,在倾斜大于5 mm时可能对剂量验证通过率产生较大影响。保持床面无倾斜是日常临床工作中一项简单但重要的质量保证工作。
Objective To simulate the effect of couch tilt on the pass rate of dosimetric verification by using two-dimensional diode array detector. Methods Ten dosimetric verification plans of intensity modulated radiotherapy （IMRT） and three- dimensional conformal radiotherapy （3DCRT） were selected. The inflatable bag was used on the treatment couch to control the difference of the value of laser light, simulating the couch tilt. The magnitude of couch tilt was respectively 1, 2, 3, 5, 7, 10 ram. The Gamma analysis with the absolute dose discrepancy of 3% and 3 mm threshold was applied to record the planned and simulated results, and the paired t test was used to analyze the results. Results Without couch tilt, the pass rate of dosimetric verification was respectively （96.10±1.65）% in IMRT and （97.50±1.98）% in 3DCRT. With couch tilt of 7 mm and 10 mm, the pass rates of patients treated by IMRT were （86.50±5.95）% and （85.40±8.53）%. For IMRT, the ratios of the pass rate without couch tilt and the pass rates with couch tilt of 7 mm and 10 mm were respectively 0.90±0.05 and 0.85± 0.08. With maximum couch tilt of 10 mm, the pass rate of patients treated by 3DCRT was （91.90±4.90） %. For 3DCRT, the ratio of the pass rate without couch tilt and the pass rates with couch tilt of 10 mm was 0.94±0.05. Compared with no couch tilt, significant differences were found in the pass rate with different couch tilts （P〉0.050）, except the pass rate of 3DCRT with couch tilt of 2 mm （P=-0.366）. Conclusion Couch tilt has little influences on the pass rate of dosimetric verification of 3DCRT. However, for IMRT, the pass rate decreases with the increase of couch tilt, and the amplitude of variation showed individual differences, and the couch tilt larger than 5 mm may have some significant effect on the pass rate of dosimetric verification. Keeping the couch without tilt is a simple but important quality assurance work in daily clinical work.
出处
《中国医学物理学杂志》
CSCD
2016年第9期881-884,902,共5页
Chinese Journal of Medical Physics
基金
湖北省自然科学基金(2012FKC143)
关键词
调强放射治疗
三维适形放疗
床面倾斜
剂量验证
通过率
intensity modulated radiotherapy
three-dimensional conformal radiotherapy
couch tilt
dosimetric verification
pass rate
