Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
Radiat Oncol. 2013 Feb 3;8:32. doi: 10.1186/1748-717X-8-32.
As the number of proton therapy centers increases, so does the need for studies which compare proton treatments between institutions and with photon therapy. However, results of such studies are highly dependent on target volume definition and treatment planning techniques. Thus, standardized methods of treatment planning are needed, particularly for proton treatment planning, in which special consideration is paid to the depth and sharp distal fall-off of the proton distribution. This study presents and evaluates a standardized method of proton treatment planning for craniospinal irradiation (CSI).
We applied our institution's planning methodology for proton CSI, at the time of the study, to an anatomically diverse population of 18 pediatric patients. We evaluated our dosimetric results for the population as a whole and for the two subgroups having two different age-specific target volumes using the minimum, maximum, and mean dose values in 10 organs (i.e., the spinal cord, brain, eyes, lenses, esophagus, lungs, kidneys, thyroid, heart, and liver). We also report isodose distributions and dose-volume histograms (DVH) for 2 representative patients. Additionally we report population-averaged DVHs for various organs.
The planning methodology here describes various techniques used to achieve normal tissue sparing. In particular, we found pronounced dose reductions in three radiosensitive organs (i.e., eyes, esophagus, and thyroid) which were identified for optimization. Mean doses to the thyroid, eyes, and esophagus were 0.2%, 69% and 0.2%, respectively, of the prescribed dose. In four organs not specifically identified for optimization (i.e., lungs, liver, kidneys, and heart) we found that organs lateral to the treatment field (lungs and kidneys) received relatively low mean doses (less than 8% of the prescribed dose), whereas the heart and liver, organs distal to the treatment field, received less than 1% of the prescribed dose.
This study described and evaluated a standardized method for proton treatment planning for CSI. Overall, the standardized planning methodology yielded consistently high quality treatment plans and perhaps most importantly, it did so for an anatomically diverse patient population.
随着质子治疗中心数量的增加，比较机构间和光子治疗的质子治疗的研究需求也在增加。然而，这些研究的结果高度依赖于靶区定义和治疗计划技术。因此，需要标准化的治疗计划方法，特别是对于质子治疗计划，其中特别考虑质子分布的深度和远端陡峭下降。本研究提出并评估了一种用于颅脊髓照射（CSI）的质子治疗计划的标准化方法。
在研究时，我们应用了我们机构的质子 CSI 计划方法，对 18 名儿科患者的解剖多样化人群进行了评估。我们使用 10 个器官（即脊髓、大脑、眼睛、晶状体、食管、肺、肾脏、甲状腺、心脏和肝脏）中的最小、最大和平均剂量值，对整个人群和具有两个不同年龄特定靶区的两个亚组进行了剂量学结果评估。我们还报告了 2 名代表性患者的等剂量分布和剂量体积直方图（DVH）。此外，我们还报告了各种器官的人群平均 DVH。
这里的规划方法描述了实现正常组织保护的各种技术。特别是，我们发现优化后三个敏感器官（即眼睛、食管和甲状腺）的剂量明显降低。甲状腺、眼睛和食管的平均剂量分别为处方剂量的 0.2%、69%和 0.2%。在未专门为优化确定的四个器官（即肺、肝、肾和心脏）中，我们发现治疗场外侧的器官（肺和肾）接受的平均剂量相对较低（低于处方剂量的 8%），而心脏和肝脏，治疗场远端的器官，接受的剂量低于处方剂量的 1%。
本研究描述并评估了一种用于 CSI 的质子治疗计划的标准化方法。总的来说，标准化的规划方法产生了高质量的治疗计划，最重要的是，它适用于解剖多样化的患者人群。
