An overlap-volume-histogram based method for rectal dose prediction and automated treatment planning in the external beam prostate radiotherapy following hydrogel injection
An overlap-volume-histogram based method for rectal dose prediction and automated treatment planning in the external beam prostate radiotherapy following hydrogel injection
复制标题
DOI：
10.1118/1.4769424
复制
发表时间：
2013-01-01
期刊：
影响因子：
3.8
通讯作者：
McNutt, Todd R.
中科院分区：
文献类型：
--
作者：
Yang, Yidong;Ford, Eric C.;McNutt, Todd R.
目的：在放射治疗前在直肠和前列腺之间注射水凝胶提供了一种可能的增加直肠剂量节省的方法。在本文中，作者评价了重叠体积直方图（OVH）度量作为预测水凝胶注射后直肠剂量的方法。OVH预测剂量是否可以作为剂量目标或约束自动化治疗planning.Methods：治疗计划进行前和posthydrogel注射21例前列腺癌患者，五场调强放疗提供78戈伊的计划靶体积（PTV）。作者使用OVH指标量化直肠和前列腺PTV之间的几何关系，该指标确定PTV指定距离内的直肠体积分数。对于OVH距离，作者选择L-20，即20%直肠重叠的PTV扩张距离。作者计算了剂量体积直方图上20%直肠体积接收的直肠剂量D-20。使用线性回归来检查L-20和D-20之间以及Δ L-20和Δ D-20之间的相关性（即，注射后L-20和D-20的变化）。此外，通过L-x-D-x线性回归，根据OVH（直肠为L-15、L-25、L-35、L-50，膀胱为L-15）预测直肠剂量D-15、D-25、D-35、D-50和膀胱剂量D-15。将预测剂量应用于5名患者的10个计划的自动治疗计划的目标。自动生成的计划进行了比较，手动生成的trial-and-error basis.Results：直肠L-20增加，剂量D-20下降，由于扩大分离的直肠所造成的水凝胶注射。线性回归显示L-20和D-20之间以及Delta L-20和Delta D-20之间存在负线性相关（r（2）分别= 0.77、0.60; p < 0.0001）。直肠保留的增加（Δ D-20）仅与注射的水凝胶的体积弱相关（r（2）= 0.17; p = 0.07），表明OVH是比水凝胶本身的体积更能预测直肠保留的指标。应用预测直肠和膀胱剂量自动规划产生可接受的治疗计划，直肠剂量减少了8个plannes.Conclusions：OVH度量可以预测直肠剂量的外束前列腺放射治疗水凝胶注射的患者。预测的剂量可以应用于自动治疗计划中的优化目标，以产生可接受的治疗计划。(C)2013年美国医学物理学家协会。[http：//dx.doi.org/10.1118/1.4769424]
Purpose: Hydrogel injected between the rectum and prostate prior to radiotherapy provides a possible means of increased dose sparing to the rectum. Here the authors evaluate the overlap volume histogram (OVH) metric as a means to predict the rectal dose following hydrogel injection. Whether OVH predicted dose can serve as the dose objective or constraint for automated treatment planning was also investigated.Methods: Treatment planning was performed on 21 prostate cancer patients both pre- and posthydrogel injection, with five-field IMRT delivering 78 Gy to the planning target volume (PTV). The authors quantify the geometrical relationship between the rectum and the prostate PTV using an OVH metric which determines the fractional volume of the rectum that is within a specified distance of the PTV. For an OVH distance the authors selected, L-20, the PTV expansion distance at which 20% of the rectum overlaps. The authors calculated the rectal dose, D-20, received by 20% of the rectum volume on the dose volume histogram. Linear regression was used to examine the correlation between the L-20 and D-20, and between Delta L-20 and Delta D-20 (i.e., the change of L-20 and D-20 posthydrogel injection). Additionally, rectal dose D-15, D-25, D-35, D-50, and bladder dose D-15 were predicted from the OVH (L-15, L-25, L-35, L-50, for rectum and L-15 for bladder) by the L-x-D-x linear regression. The predicted doses were applied to the objectives for automated treatment planning of ten plans from five patients. Automatically generated plans were compared with plans manually generated on trial-and-error basis.Results: The rectal L-20 was increased and dose D-20 decreased due to the enlarged separation of rectum caused by the hydrogel injection. Linear regression showed an inverse linear correlation between L-20 and D-20, and between Delta L-20 and Delta D-20 (r(2) = 0.77, 0.60, respectively; p < 0.0001). The increase in rectal sparing (Delta D-20) is only weakly correlated with the volume of injected hydrogel (r(2) = 0.17; p = 0.07), indicating OVH is a more predictive indicator of rectal sparing than the volume of hydrogel itself. Application of the predicted rectum and bladder doses to automated planning produced acceptable treatment plans, with rectal dose reduced for eight of ten plans.Conclusions: The OVH metric can predict the rectal dose in the external beam prostate radiotherapy for patients with hydrogel injection. The predicted doses can be applied to the objectives of optimization in automated treatment planning to produce acceptable treatment plans. (C) 2013 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.4769424]