Klinik für Strahlentherapie und Radioonkologie, Universitätsmedizin Mannheim, Universität Heidelberg, Theodor-Kutzer-Ufer 1-3, 68135, Mannheim, Germany.
Strahlenther Onkol. 2012 Aug;188(8):653-9. doi: 10.1007/s00066-012-0144-x. Epub 2012 Jun 29.
Conventional algorithms show uncertainties in dose calculation already for three-dimensional conformal radiotherapy (3D-CRT). Intensity-modulated radiotherapy (IMRT) might even increase these. We wanted to assess differences in dose distribution for pencil beam (PB), collapsed cone (CC), and Monte Carlo (MC) algorithm for both 3D-CRT and IMRT in patients with mediastinal Hodgkin lymphoma.
Based on 20 computed tomograph (CT) datasets of patients with mediastinal Hodgkin lymphoma, we created treatment plans according to the guidelines of the German Hodgkin Study Group (GHSG) with PB and CC algorithm for 3D-CRT and with PB and MC algorithm for IMRT. Doses were compared for planning target volume (PTV) and organs at risk.
For 3D-CRT, PB overestimated PTV(95) and V(20) of the lung by 6.9% and 3.3% and underestimated V(10) of the lung by 5.8%, compared to the CC algorithm. For IMRT, PB overestimated PTV(95), V(20) of the lung, V(25) of the heart and V(10) of the female left/right breast by 8.1%, 25.8%, 14.0% and 43.6%/189.1%, and underestimated V(10) of the lung, V(4) of the heart and V(4) of the female left/right breast by 6.3%, 6.8% and 23.2%/15.6%, compared to MC.
The PB algorithm underestimates low doses to the organs at risk and overestimates dose to PTV and high doses to the organs at risk. For 3D-CRT, a well-modeled PB algorithm is clinically acceptable; for IMRT planning, however, an advanced algorithm such as CC or MC should be used at least for part of the plan optimization.
对于三维适形放疗（3D-CRT），常规算法在剂量计算方面已经存在不确定性。调强放疗（IMRT）甚至可能会增加这些不确定性。我们希望评估在纵隔霍奇金淋巴瘤患者中，对于 3D-CRT 的笔形束（PB）、坍缩束（CC）和蒙特卡罗（MC）算法以及对于 IMRT 的 PB 和 MC 算法，剂量分布的差异。
基于 20 例纵隔霍奇金淋巴瘤患者的计算机断层扫描（CT）数据集，我们根据德国霍奇金研究组（GHSG）的指南创建了治疗计划，对于 3D-CRT 使用 PB 和 CC 算法，对于 IMRT 使用 PB 和 MC 算法。比较了计划靶区（PTV）和危及器官的剂量。
对于 3D-CRT，与 CC 算法相比，PB 高估了 PTV(95)和肺的 V(20)分别为 6.9%和 3.3%，低估了肺的 V(10)为 5.8%。对于 IMRT，PB 高估了 PTV(95)、肺的 V(20)、心脏的 V(25)和女性左右乳房的 V(10)分别为 8.1%、25.8%、14.0%和 43.6%/189.1%，低估了肺的 V(10)、心脏的 V(4)和女性左右乳房的 V(4)分别为 6.3%、6.8%和 23.2%/15.6%，与 MC 算法相比。
PB 算法低估了危及器官的低剂量，高估了 PTV 和危及器官的高剂量。对于 3D-CRT，建模良好的 PB 算法在临床上是可以接受的；然而，对于 IMRT 计划，至少应该在部分计划优化中使用 CC 或 MC 等高级算法。
