Analysis of interfraction prostate motion using megavoltage cone beam computed tomography
Analysis of interfraction prostate motion using megavoltage cone beam computed tomography
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DOI：
10.1016/j.ijrobp.2008.07.002
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发表时间：
2008-11-01
影响因子：
7
通讯作者：
Buatti, John M.
中科院分区：
文献类型：
--
作者：
Bylund, Kevin C.;Bayouth, John E.;Buatti, John M.
目的：确定interfraction前列腺运动的程度和其组成部分测量使用每日兆电压（MV）锥形束计算机断层扫描（CBCT）imaging.Methods和Materials：共984每日MV CBCT图像24例接受确定性调强放疗局限性前列腺癌进行了回顾性分析。基于MV CBCT与计划CT数据集的医生配准，治疗前治疗床移位被用作每日分次间运动的测量。进行离线骨配准以将骨错位与内部器官运动分开。结果：平均分次间前列腺运动为6.7 mm，最大单轴偏差在前后（AP）方向。最大的位置不准确性是由骨错位的系统偏差引起的，而随机偏差则是由骨错位和前列腺内部运动引起的。总的来说，所有运动与治疗开始后的天数或治疗计划时的平均直肠大小无关。观察者间变异在AP方向最大，在有经验的观察者中减少，在观察者内研究中进一步减少。结论：MV CBCT是一种实用的日常定位直接方法，与常规三维适形调强放疗边缘相比，MV CBCT显示了明显的分次间运动，与其他方式测量的结果相似。(C)2008年爱思唯尔公司
Purpose: Determine the degree of interfraction prostate motion and its components measured by using daily mega-voltage (MV) cone beam computed tomography (CBCT) imaging.Methods and Materials: A total of 984 daily MV CBCT images from 24 patients undergoing definitive intensity-modulated radiotherapy for localized prostate cancer were analyzed retrospectively. Pretreatment couch shifts, based on physician registration of MV CBCT to planning CT data sets, were used as a measure of daily interfraction motion. Off-line bony registration was performed to separate bony misalignment from internal organ motion. Interobserver and intraobserver variation studies were performed on 20 MV CBCT images.Results: Mean interfraction prostate motion was 6.7 mm, with the greatest single-axis deviation ill the anterior-posterior (AP) direction. The largest positional inaccuracy was accounted for by systematic deviations in bony misalignment, whereas random deviations occurred from bony misalignment and internal prostate motion. In the aggregate, All motion did not correlate with days elapsed since beginning therapy or on average with rectal size at treatment planning. Interobserver variation was greatest in the AP direction, decreased in experienced observers, and further decreased in intraobserver studies. Mean interfraction motion during the first 6 days of therapy, when used as a subsequent offset, reduced acceptable All planning target volume margins by 50%.Conclusion: The MV CBCT is a practical direct method of daily localization that shows significant interfraction motion with respect to conventional three-dimensional conformal and intensity-modulated radiotherapy margins, similar to that measured in other modalities. (C) 2008 Elsevier Inc.