目的:分析、比较笔形束卷积算法(PBC)和各向异性解析算法(AAA)在非小细胞肺癌(NSCLC)调强放疗计划设计中的剂量学差异。方法:随机选择7例NSCLC患者,采用Eclipse version 7.3.10计划系统提供的PBC算法和AAA算法对每例NSCLC进行IMRT的计...目的:分析、比较笔形束卷积算法(PBC)和各向异性解析算法(AAA)在非小细胞肺癌(NSCLC)调强放疗计划设计中的剂量学差异。方法:随机选择7例NSCLC患者,采用Eclipse version 7.3.10计划系统提供的PBC算法和AAA算法对每例NSCLC进行IMRT的计划设计,比较靶区及危及器官的剂量分布、DVH等指标。结果:两种算法获得治疗计划的靶区剂量均匀性和适形度均无明显差别,食管、心脏、脊髓等危及器官的受量也基本相同。结论:对于NSCLC,剂量计算应采用受呼吸时相影响更小的AAA算法。展开更多
Purpose: To introduce a practical method of using an Electron Density Phantom (EDP) to evaluate different dose calculation algorithms for photon beams in a treatment planning system (TPS) and to commission the Anisotr...Purpose: To introduce a practical method of using an Electron Density Phantom (EDP) to evaluate different dose calculation algorithms for photon beams in a treatment planning system (TPS) and to commission the Anisotropic Analytical Algorithm (AAA) with inhomogeneity correction in Varian Eclipse TPS. Methods and Materials: The same EDP with various tissue-equivalent plugs (water, lung exhale, lung inhale, liver, breast, muscle, adipose, dense bone, trabecular bone) used to calibrate the computed tomography (CT) simulator was adopted to evaluate different dose calculation algorithms in a TPS by measuring the actual dose delivered to the EDP. The treatment plans with a 6-Megavolt (MV) single field of 20 × 20, 10 × 10, and 4 × 4 cm2 field sizes were created based on the CT images of the EDP. A dose of 200 cGy was prescribed to the exhale-lung insert. Dose calculations were performed with AAA with inhomogeneity correction, Pencil Beam Convolution (PBC), and AAA without inhomogeneity correction. The plans were delivered and the actual doses were measured using radiation dosimetry devices MapCheck, EDR2-film, and ionization chamber respectively. Measured doses were compared with the calculated doses from the treatment plans. Results: The calculated dose using the AAA with inhomogeneity correction was most consistent with the measured dose. The dose discrepancy for all types of tissues covered by beam fields is at the level of 2%. The effect of AAA inhomogeneity correction for lung tissues is over 14%. Conclusions: The use of EDP and Map Check to evaluate and commission the dose calculation algorithms in a TPS is practical. In Varian Eclipse TPS, the AAA with inhomogeneity correction should be used for treatment planning especially when lung tissues are involved in a small radiation field.展开更多
文摘目的:分析、比较笔形束卷积算法(PBC)和各向异性解析算法(AAA)在非小细胞肺癌(NSCLC)调强放疗计划设计中的剂量学差异。方法:随机选择7例NSCLC患者,采用Eclipse version 7.3.10计划系统提供的PBC算法和AAA算法对每例NSCLC进行IMRT的计划设计,比较靶区及危及器官的剂量分布、DVH等指标。结果:两种算法获得治疗计划的靶区剂量均匀性和适形度均无明显差别,食管、心脏、脊髓等危及器官的受量也基本相同。结论:对于NSCLC,剂量计算应采用受呼吸时相影响更小的AAA算法。
文摘Purpose: To introduce a practical method of using an Electron Density Phantom (EDP) to evaluate different dose calculation algorithms for photon beams in a treatment planning system (TPS) and to commission the Anisotropic Analytical Algorithm (AAA) with inhomogeneity correction in Varian Eclipse TPS. Methods and Materials: The same EDP with various tissue-equivalent plugs (water, lung exhale, lung inhale, liver, breast, muscle, adipose, dense bone, trabecular bone) used to calibrate the computed tomography (CT) simulator was adopted to evaluate different dose calculation algorithms in a TPS by measuring the actual dose delivered to the EDP. The treatment plans with a 6-Megavolt (MV) single field of 20 × 20, 10 × 10, and 4 × 4 cm2 field sizes were created based on the CT images of the EDP. A dose of 200 cGy was prescribed to the exhale-lung insert. Dose calculations were performed with AAA with inhomogeneity correction, Pencil Beam Convolution (PBC), and AAA without inhomogeneity correction. The plans were delivered and the actual doses were measured using radiation dosimetry devices MapCheck, EDR2-film, and ionization chamber respectively. Measured doses were compared with the calculated doses from the treatment plans. Results: The calculated dose using the AAA with inhomogeneity correction was most consistent with the measured dose. The dose discrepancy for all types of tissues covered by beam fields is at the level of 2%. The effect of AAA inhomogeneity correction for lung tissues is over 14%. Conclusions: The use of EDP and Map Check to evaluate and commission the dose calculation algorithms in a TPS is practical. In Varian Eclipse TPS, the AAA with inhomogeneity correction should be used for treatment planning especially when lung tissues are involved in a small radiation field.
