Recently published Medical Physics Practice Guideline 5.a. (MPPG 5.a.) by American Association of Physicists in Medicine (AAPM) sets the minimum requirements for treatment planning system (TPS) dose algorithm commissi...Recently published Medical Physics Practice Guideline 5.a. (MPPG 5.a.) by American Association of Physicists in Medicine (AAPM) sets the minimum requirements for treatment planning system (TPS) dose algorithm commissioning and quality assurance (QA). The guideline recommends some validation tests and tolerances based primarily on published AAPM task group reports and the criteria used by IROC Houston. We performed the commissioning and validation of the dose algorithms for both megavoltage photon and electron beams on three linacs following MPPG 5.a. We designed the validation experiments in an attempt to highlight the evaluation method and tolerance criteria recommended by the guideline. It seems that comparison of dose profiles using in-water scan is an effective technique for basic photon and electron validation. IMRT/VMAT dose calculation is recommended to be tested with some TG-119 and clinical cases, but no consensus of the tolerance exists. Extensive validation tests have provided the better understanding of the accuracy and limitation of a specific dose calculation algorithm. We believe that some tests and evaluation criteria given in the guideline can be further refined.展开更多
目的比较乳腺癌保乳术后调强放疗(IMRT)的各向异性算法(AAA)与笔形束卷积算法(PBC)形成的治疗计划,分析在靶区的剂量均匀性HI、靶区适形度CI、双肺照射剂量与体积以及心脏照射剂量与体积的差异。方法选取乳腺癌保乳术后20例逆向调强计划...目的比较乳腺癌保乳术后调强放疗(IMRT)的各向异性算法(AAA)与笔形束卷积算法(PBC)形成的治疗计划,分析在靶区的剂量均匀性HI、靶区适形度CI、双肺照射剂量与体积以及心脏照射剂量与体积的差异。方法选取乳腺癌保乳术后20例逆向调强计划和20例正向调强计划,6 MV X线处方剂量靶区为50 Gy,分别用AAA算法和PBC算法模型计算,在两种算法剂量体积直方图上比较靶区、双肺与心脏照射剂量和体积。结果逆向调强中AAA算法超过处方剂量的体积与PBC算法基本相似;靶区平均剂量低于PBC算法73.91 c Gy,均匀性指数HI高于PBC算法2.5%,双肺的V20高于PBC算法2.5%,心脏平均受照剂量低于PBC算法53.39 c Gy。靶区适形数CI显著高于PBC算法5.7%。正向调强中AAA算法超过处方剂量的体积高于PBC算法8.5%,靶区平均剂量高于PBC算法91.03 c Gy,均匀性高于PBC算法10.1%,心脏平均受照剂量高于PBC算法3.37 c Gy;适形指数CI高于PBC算法5.9%,肺的V20显著高于PBC算法0.9%(P<0.05)。结论乳腺癌调强计划AAA算法适形度优于PBC算法,但肺V20高于PBC算法。展开更多
文摘Recently published Medical Physics Practice Guideline 5.a. (MPPG 5.a.) by American Association of Physicists in Medicine (AAPM) sets the minimum requirements for treatment planning system (TPS) dose algorithm commissioning and quality assurance (QA). The guideline recommends some validation tests and tolerances based primarily on published AAPM task group reports and the criteria used by IROC Houston. We performed the commissioning and validation of the dose algorithms for both megavoltage photon and electron beams on three linacs following MPPG 5.a. We designed the validation experiments in an attempt to highlight the evaluation method and tolerance criteria recommended by the guideline. It seems that comparison of dose profiles using in-water scan is an effective technique for basic photon and electron validation. IMRT/VMAT dose calculation is recommended to be tested with some TG-119 and clinical cases, but no consensus of the tolerance exists. Extensive validation tests have provided the better understanding of the accuracy and limitation of a specific dose calculation algorithm. We believe that some tests and evaluation criteria given in the guideline can be further refined.
文摘目的比较乳腺癌保乳术后调强放疗(IMRT)的各向异性算法(AAA)与笔形束卷积算法(PBC)形成的治疗计划,分析在靶区的剂量均匀性HI、靶区适形度CI、双肺照射剂量与体积以及心脏照射剂量与体积的差异。方法选取乳腺癌保乳术后20例逆向调强计划和20例正向调强计划,6 MV X线处方剂量靶区为50 Gy,分别用AAA算法和PBC算法模型计算,在两种算法剂量体积直方图上比较靶区、双肺与心脏照射剂量和体积。结果逆向调强中AAA算法超过处方剂量的体积与PBC算法基本相似;靶区平均剂量低于PBC算法73.91 c Gy,均匀性指数HI高于PBC算法2.5%,双肺的V20高于PBC算法2.5%,心脏平均受照剂量低于PBC算法53.39 c Gy。靶区适形数CI显著高于PBC算法5.7%。正向调强中AAA算法超过处方剂量的体积高于PBC算法8.5%,靶区平均剂量高于PBC算法91.03 c Gy,均匀性高于PBC算法10.1%,心脏平均受照剂量高于PBC算法3.37 c Gy;适形指数CI高于PBC算法5.9%,肺的V20显著高于PBC算法0.9%(P<0.05)。结论乳腺癌调强计划AAA算法适形度优于PBC算法,但肺V20高于PBC算法。
