CAJ | 학술논문

目的：分析Oncentra中异质性校正对绝对剂量验证的影响。方法应用医科达Oncentra v4．1SP2计划系统设计36例计划，其中逆向调强计划18例，三维适形及简单调强计划（总子野数≤10）18例，对应每类计划，头颈部、胸部、腹部计划各6例。将以上计划移植到固体水上，分别在使用和不使用异质性校正的条件下，计算出电离室体积内的平均剂量，比较两者与电离室测量所得剂量的差异。结果对于所有病例，不使用均质性校准与同时使用均质校准且将电离室密度指定为水时TPS计算所得结果完全一致。除头颈部机架归零时6例调强病例在仅使用非均质较正时所得结果更接近实测结果外，其余病例，均是仅使用非均质校正时，TPS计算所得结果与实测值偏差较大。仅使用非均质校正时与实测值的差异与另外两种情况下TPS计算值与实测值的差异相比有统计学意义（P＜0．05）。结论在利用Precise加速器及Oncentra v4．1SP2 CC算法进行精确放射治疗时，点剂量验证应在机架不归零的情况下测试，且TPS中计算时可在不使用均质修正或使用非均质修正且将电离室密度指定为水的情况下进行。
목적：분석Oncentra중이질성교정대절대제량험증적영향。방법응용의과체Oncentra v4．1SP2계화계통설계36례계화，기중역향조강계화18례，삼유괄형급간단조강계화（총자야수≤10）18례，대응매류계화，두경부、흉부、복부계화각6례。장이상계화이식도고체수상，분별재사용화불사용이질성교정적조건하，계산출전리실체적내적평균제량，비교량자여전리실측량소득제량적차이。결과대우소유병례，불사용균질성교준여동시사용균질교준차장전리실밀도지정위수시TPS계산소득결과완전일치。제두경부궤가귀령시6례조강병례재부사용비균질교정시소득결과경접근실측결과외，기여병례，균시부사용비균질교정시，TPS계산소득결과여실측치편차교대。부사용비균질교정시여실측치적차이여령외량충정황하TPS계산치여실측치적차이상비유통계학의의（P＜0．05）。결론재이용Precise가속기급Oncentra v4．1SP2 CC산법진행정학방사치료시，점제량험증응재궤가불귀령적정황하측시，차TPS중계산시가재불사용균질수정혹사용비균질수정차장전리실밀도지정위수적정황하진행。
Objective To analyze the effect of inhomogeneity correction on absolute dose verification in oncentra.Meth-ods Oncentra v4.1SP2 was used to set up 36 plans,18 were reverse intensity-modulated plan,and 18 were three dimensional conformal and simple intensity modulated plan( whose sub-field smaller than 11) .There were 6 patients each for head and neck, chest and abdomen in both plans.Transplanting all the plans to the Quality Assurance( QA) phantom and calculate the mean dose of the detector use the inhomogeneity correction or not,and the difference between mean dose and detector measured were com-pared.Results We obtained the same results for all the cases when we calculate the point dose and set the chamber density to water,whether use inhomogeneity correction or not.For all the dose difference between calculated by TPS and measured by cham-ber,the bigger difference were found when only use the inhomogeneity correction by TPS,except for 6 cases of head and neck whose gantry angle set to zero when make the dose validate.There were significant differences between the difference obtained when only use inhomogeneity correction and the difference obtained use inhomogeneity correction and set the chamber density to water(P<0.05).Conclusion The gantry angle must be set to original when we make the absolute dose validation for treatment planning calculated by CC in Oncentra v4.1SP2 and Precise accelerator,at the same time use inhomogeneity correction and set the chamber density to water or not use inhomogeneity correction for the dose calculation.