Wittkämper F W, Mijnheer B J, van Kleffens H J
Radiotherapy Department, The Netherlands Cancer Institute (Antoni van Leeuwenhoekhuis), Amsterdam.
Radiother Oncol. 1988 Apr;11(4):405-14. doi: 10.1016/0167-8140(88)90212-5.
As part of a quality assurance program in The Netherlands, the performance of computer planning systems was tested. Relative dose values, determined with an ionization chamber, were compared with dose values obtained from locally applied computer planning systems. Several clinically relevant situations were investigated: perpendicular incident beams, wedged beams, oblique incident beams, variable source-surface distances (SSD) and off-axis planes. The mean value of the ratios of calculated to measured dose values is 0.994, with an uncertainty of 2.4% (1 S.D.) and a maximum deviation of 9%, for all combinations of energies, planning systems and geometries investigated. The uncertainty for each situation separately was less than 2% (1 S.D.), except for the wedged beams and off-axis plane, which showed uncertainties of 2.6% (1 S.D.). Part of the additional uncertainty for the wedged beams originates from the value chosen for the wedge factor. Systematic deviations between calculated and measured dose values were investigated for three commercially available planning systems, separately. The mean deviation was smaller than 1% (1 S.D.), for most situations. Only for the wedged beams, larger deviations, up to a mean deviation of 2.6%, were observed.
作为荷兰质量保证计划的一部分，对计算机治疗计划系统的性能进行了测试。将电离室测定的相对剂量值与本地应用的计算机治疗计划系统获得的剂量值进行比较。研究了几种临床相关情况：垂直入射束、楔形束、斜入射束、可变源皮距（SSD）和离轴平面。对于所研究的所有能量、治疗计划系统和几何形状的组合，计算剂量值与测量剂量值之比的平均值为0.994，不确定度为2.4%（1标准差），最大偏差为9%。除楔形束和离轴平面的不确定度为2.6%（1标准差）外，每种情况单独的不确定度均小于2%（1标准差）。楔形束额外不确定度的部分原因来自所选的楔形因子值。分别对三种商用治疗计划系统计算剂量值与测量剂量值之间的系统偏差进行了研究。在大多数情况下，平均偏差小于1%（1标准差）。仅对于楔形束，观察到较大偏差，平均偏差高达2.6%。
