Proton therapy dose distribution comparison between Monte Carlo and a treatment planning system for pediatric patients with ependymoma
Proton therapy dose distribution comparison between Monte Carlo and a treatment planning system for pediatric patients with ependymoma
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DOI：
10.1118/1.4736413
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发表时间：
2012-08-01
期刊：
影响因子：
3.8
通讯作者：
Merchant, Thomas E.
中科院分区：
文献类型：
--
作者：
Jia, Yingcui;Beltran, Chris;Merchant, Thomas E.
目的：比较使用蒙特卡罗（MC）系统和临床治疗计划系统（TPS）计算的儿科室管膜瘤患者的剂量分布。方法：从TPS中导出10例采用双散射质子治疗的小儿室管膜瘤患者的计划，并在MC系统中计算。对远端边缘（80%和20%）、远端脱落（80%到20%）、视场宽度（50%到50%）和半影（80%到20%）进行逐场比较。此外，还比较了全计划的目标剂量。结果：在10例患者的32个视野中，MC和TPS在中轴80%和20%处远端边缘的平均差异分别为-1.9 +/- 1.7 mm （p < 0.001）和-0.6 +/- 2.3 mm （p = 0.13）。排除骨内或空腔内的磁场，80%的差异为-0.9 +/- 1.7 mm （p = 0.09）。负值表明MC比TPS平均浅。10例患者63个视场宽度的平均差值为-0.7 +/- 1.0 mm (p < 0.001)，阴性表明MC平均视场宽度较小。半影的平均差异为2.3 +/- 2.1 mm （p < 0.001）。平均临床靶体积剂量差值为-1.8% (p = 0.001)，为负表明MC的剂量较低。结论：总体而言，MC系统和TPS在视场宽度、20%远端边缘和靶覆盖率方面的结果相似。对于80%的远端边缘和外侧半影，有轻微的分歧；然而，差异小于2毫米，主要发生在高度异质性的地区。这些差异突出表明，不能自动认为TPS剂量计算是正确的。(C) 2012年美国医学物理学家协会。[http://dx.doi.org/10.1118/1.4736413]
Purpose: Compare dose distributions for pediatric patients with ependymoma calculated using a Monte Carlo (MC) system and a clinical treatment planning system (TPS).Methods: Plans from ten pediatric patients with ependymoma treated using double scatter proton therapy were exported from the TPS and calculated in our MC system. A field by field comparison of the distal edge (80% and 20%), distal fall off (80% to 20%), field width (50% to 50%), and penumbra (80% to 20%) were examined. In addition, the target dose for the full plan was compared.Results: For the 32 fields from the 10 patients, the average differences of distal edge at 80% and 20% on central axis between MC and TPS are -1.9 +/- 1.7 mm (p < 0.001) and -0.6 +/- 2.3 mm (p = 0.13), respectively. Excluding the fields that ranged out in bone or an air cavity, the 80% difference was -0.9 +/- 1.7 mm (p = 0.09). The negative value indicates that MC was on average shallower than TPS. The average difference of the 63 field widths of the 10 patients is -0.7 +/- 1.0 mm (p < 0.001), negative indicating on average the MC had a smaller field width. On average, the difference in the penumbra was 2.3 +/- 2.1 mm (p < 0.001). The average of the mean clinical target volume dose differences is -1.8% (p = 0.001), negative indicating a lower dose for MC.Conclusions: Overall, the MC system and TPS gave similar results for field width, the 20% distal edge, and the target coverage. For the 80% distal edge and lateral penumbra, there was slight disagreement; however, the difference was less than 2 mm and occurred primarily in highly heterogeneous areas. These differences highlight that the TPS dose calculation cannot be automatically regarded as correct. (C) 2012 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.4736413]