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1、-798-2008年9月中国医学物理学杂志Sep.,2008第25卷第5期ChineseJournalofMedicalPhysicsVol.25.No.5影响调强放疗绝对剂量的主要因素及应对措施姜瑞瑶,熊霏,黄国锋,曹征,李兆斌,傅深(上海交大附属第六人民医院肿瘤放疗科,上海200233)摘要:目的:验证调强放射治疗的绝对剂量误差,探索影响调强放疗绝对剂量的因素及其应对措施。方法:将20例准备实施调强放疗病人的实际治疗计划,用标准水模体进行计划移植,生成验证计划并计算体模内电离室测量点的计划剂量,执行验证计划的照射,用电离室进行实际物理绝对剂量测量,
2、计算实际测量剂量值和计划剂量值的百分相对误差。分析影响调强放疗绝对剂量误差的主要因素,采取相应改进措施,验证另80例调强放疗的绝对剂量,比较前20例与改进后80例调强放疗绝对剂量验证结果。结果:前20例调强放疗绝对剂量百分相对误差分布范围是-8.00%~5.00%,平均误差为-2.01%,标准差为3.55%。采取相应改进措施后,80例调强放疗绝对剂量百分相对误差全部在4.4%以内,分布范围缩小到-4.4%~2.5%,平均误差为-1.49%,比前20例平均误差下降25.9%,标准差为1.40%,比前20例下降60.6%。结论:分析影响调强放疗绝对剂量的因
3、素,采取必要的应对措施,能够有效提高调强放射治疗绝对剂量的准确性。关键词:调强放射治疗;绝对剂量;验证中图分类号:R730.55文献标识码:A文章编号:1005-202X(2008)05-0798-03MainInfluentFactorsonAbsoluteDoseofIntensity-ModulatedRadiationTherapyandCountermeasuresJIANGRui-yao,XIONGFei,HUANGGuo-feng,CAOZheng,LIZhao-bin,FUShen(DepartmentofRadiationOncolo
4、gy,6thPeople,sHospital,JiaotongUniversity,Shanghai200233,China)Abstract:Objective:ToverifytheabsolutedoseaccuracyofIMRTandexploretheMaininfluentfactorsonabsolutedoseofintensity-modulatedradiatedtherapyandcountermeasures.Methods:Conductinghybridplansusingphantomgeometryand20cases
5、patient'sincidentbeamfluenceforIMRT.IrradiationdoseweremeasuredbyionizationchambertoverifytheabsolutedoseaccuracyofIMRT,calculatetherelativedifferencebetweenmeasureddoseandplanneddose.AnalyzingthemaininfluentfactorsonabsolutedoseofIMRTandtakingsomecountermeasures,verifytheabsolu
6、tedoseaccuracyofIMRTforanother80cases.Comparetheresultofabsolutedoseverificationbetweenthefirst20casesandtheimproving80cases.Results:Relativedifferencebetweenmeasureddoseandplanneddosearewithin-8.00%~5.00%forfirst20cases,averagedifferencewas-2.01%,standarddeviationwas3.55%.After
7、takesomeimprovingcountermeasures,relativedifferencebetweenmeasureddoseandplanneddosearewithin-4.4%~2.5%for80cases,averagedifferencewas-1.49%,decreased25.9%,standarddeviationwas1.40%,decreased60.6%.Conclusion:ItisefficienttoimprovetheabsolutedoseaccuracyofIMRTbyanalyzingthemainin
8、fluentfactorsonabsolutedoseofintensity-modulate