Westermann C F, Mijnheer B J, van Kleffens H J
Radiother Oncol. 1984 Mar;1(4):339-47. doi: 10.1016/s0167-8140(84)80022-5.
The performance of computer planning systems has been tested by comparing calculations using the local beam data and computer facilities with measurements at the local installations. Relative absorbed dose distributions have been determined in a water phantom, irradiated with megavoltage photon beams with qualities from 60Co up to 25 MV. Three clinically relevant situations were studied: oblique incidence, tangential beams and wedged fields. For 45 degrees oblique incidence the mean deviation between the calculated and measured relative absorbed dose was less than 1%. Individual deviations, however, ranged from -2% up to +7%. A systematic difference, due to a straightforward application of the modified effective SSD method, was observed. For tangential irradiation the planning systems which do not consider the lack of scattering material showed deviations up to 8% between calculated and measured relative absorbed dose. For wedged beams, especially when they impinge obliquely on the phantom surface, differences were found up to 10%. Differences up to 20% were found for a point in the build-up region of an obliquely impinging wedged beam. From this study it can be concluded that planning systems may produce clinically unacceptable errors.
通过将使用本地射束数据和计算机设备进行的计算结果与本地装置的测量结果进行比较，对计算机治疗计划系统的性能进行了测试。在用水模体中，用能量范围从60Co到25MV的兆伏级光子束进行照射，确定了相对吸收剂量分布。研究了三种临床相关情况：斜入射、切线野和楔形野。对于45度斜入射，计算得到的和测量得到的相对吸收剂量之间的平均偏差小于1%。然而，个别偏差范围从-2%到+7%。观察到由于直接应用修正后的有效源皮距方法而产生的系统差异。对于切线照射，那些没有考虑散射物质缺乏情况的治疗计划系统，计算得到的和测量得到的相对吸收剂量之间的偏差高达8%。对于楔形野，特别是当它们斜向照射到模体表面时，发现差异高达10%。对于斜入射楔形野的建成区中的一个点，发现差异高达20%。从这项研究可以得出结论，治疗计划系统可能会产生临床上不可接受的误差。
