MRI-guided prostate radiation therapy planning: Investigation of dosimetric accuracy of MRI-based dose planning
MRI-guided prostate radiation therapy planning: Investigation of dosimetric accuracy of MRI-based dose planning
复制标题
DOI：
10.1016/j.radonc.2011.01.012
复制
发表时间：
2011-03-01
影响因子：
5.7
通讯作者：
Salvado, Olivier
中科院分区：
文献类型：
--
作者：
Lambert, Jonathan;Greer, Peter B.;Salvado, Olivier
背景和目的：剂量计划需要CT扫描提供剂量计算的电子密度分布。与CT相比，MR可提供上级软组织对比度，单独使用MR进行前列腺规划将为患者提供更多益处，例如降低成本。本研究比较了基于单独MR的剂量计算与体电子密度分配与基于CT的前列腺放疗剂量计算的准确性。材料和方法：对39名前列腺患者的CT和整个骨盆MR图像进行轮廓绘制。将具有均匀密度的计划和具有分配给骨和组织的体积密度值的计划与患者的金标准全密度CT计划进行比较。使用有效深度测量值计算骨的最佳体积密度。使用ICRU点剂量、剂量体积直方图和Chi比较对计划进行评价。研究了CT和MR扫描的空间均匀性差异。结果：CT大块骨和组织密度计划的计算剂量比相应的全密度CT计划高0.1 +/-0.6%（平均值+/-1 SD）。MR大块骨和组织密度计划比全密度CT计划低1.3 ± 0.8%。CT均匀密度计划和MR均匀密度计划分别低1.4 +/-0.9%和2.6 +/-0.9%。对DVH图上的特定点进行的配对t检验表明，除两个例外外，所有体电子密度计划的DVH上的点都是等效的。在Pinnacle和Eclipse上计算的剂量之间无显著差异。六名患者的剂量分布产生的可接受的范围外的值时，MR为基础的计划相比，全密度plann.Conclusions：MR单独的体积密度规划是可行的骨分配的密度，但是，手动分割的骨MR图像将不得不用自动方法取代。MR体积密度计划的主要剂量差异是由于MR床面和骨盆线圈引入的患者外部轮廓差异。(C)2011爱思唯尔爱尔兰有限公司保留所有权利。放射治疗和肿瘤学98（2011）330 - 334
Background and purpose: Dose planning requires a CT scan which provides the electron density distribution for dose calculation. MR provides superior soft tissue contrast compared to CT and the use of MR-alone for prostate planning would provide further benefits such as lower cost to the patient. This study compares the accuracy of MR-alone based dose calculations with bulk electron density assignment to CT-based dose calculations for prostate radiotherapy.Materials and methods: CT and whole pelvis MR images were contoured for 39 prostate patients. Plans with uniform density and plans with bulk density values assigned to bone and tissue were compared to the patient's gold standard full density CT plan. The optimal bulk density for bone was calculated using effective depth measurements. The plans were evaluated using ICRU point doses, dose volume histograms, and Chi comparisons. Differences in spatial uniformity were investigated for the CT and MR scans.Results: The calculated dose for CT bulk bone and tissue density plans was 0.1 +/- 0.6% (mean +/- 1 SD) higher than the corresponding full density CT plan. MR bulk bone and tissue density plans were 1.3 +/- 0.8% lower than the full density CT plan. CT uniform density plans and MR uniform density plans were 1.4 +/- 0.9% and 2.6 +/- 0.9% lower, respectively. Paired t-tests performed on specific points on the DVH graphs showed that points on DVHs for all bulk electron density plans were equivalent with two exceptions. There was no significant difference between doses calculated on Pinnacle and Eclipse. The dose distributions of six patients produced Chi values outside the acceptable range of values when MR-based plans were compared to the full density plan.Conclusions: MR-alone bulk density planning is feasible provided bone is assigned a density, however, manual segmentation of bone on MR images will have to be replaced with automatic methods. The major dose differences for MR bulk density plans are due to differences in patient external contours introduced by the MR couch-top and pelvic coil. (C) 2011 Elsevier Ireland Ltd All rights reserved. Radiotherapy and Oncology 98 (2011) 330-334