CHARACTERIZING INTERFRACTION VARIATIONS AND THEIR DOSIMETRIC EFFECTS IN PROSTATE CANCER RADIOTHERAPY
CHARACTERIZING INTERFRACTION VARIATIONS AND THEIR DOSIMETRIC EFFECTS IN PROSTATE CANCER RADIOTHERAPY
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DOI：
10.1016/j.ijrobp.2010.05.008
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发表时间：
2011-03-01
影响因子：
7
通讯作者：
Li, Allen
中科院分区：
文献类型：
--
作者：
Peng, Cheng;Ahunbay, Ergun;Li, Allen
目的：为了定量表征的interfraction的变化和它们的剂量学效应在放射治疗前列腺癌。方法和材料：共486每日计算机断层扫描（CT）集20例前列腺癌患者的治疗与每日CT引导下的重新定位使用直线加速器和CT的轨道组合进行了分析。前列腺，直肠和膀胱，描绘在每个每日CT数据集，与计划CT扫描进行比较。几个数量，包括骰子的系数和最大重叠率，被用来表征级分间的变化。通过将原始计划应用于日常CT扫描并考虑适当的重新定位来重建所提供的剂量。结果：骨配准后的平均前列腺Dice系数和最大重叠率分别为69.7% +/- 13.8%（标准差）和85.6% +/- 7.8%（标准差）。对于目标覆盖和/或正常结构保留，每日输送剂量分布通常劣于计划剂量分布。例如，对于约5%的治疗分次，与其计划值相比，接受100%处方剂量的前列腺体积显著减少（15-20%）。分割间变化的幅度及其剂量学效应表明，从统计学上讲，目前使用前列腺对准的标准重新定位可能适用于三分之二的分割，但对于其余的分割，需要更好的在线校正策略，如在线重新规划。根据器官位移和变形参数量化的解剖学变化，可以使用不同的自适应校正方案来校正前列腺碎片间的变化。大约三分之一的治疗部分需要在线重新计划。(C)2011 Elsevier Inc.
Purpose: To quantitatively characterize the interfraction variations and their dosimetric effects in radiotherapy for prostate cancer.Methods and Materials: A total of 486 daily computed tomography (CT) sets acquired for 20 prostate cancer patients treated with daily CT-guided repositioning using a linear accelerator and CT-on-rail combination were analyzed. The prostate, rectum, and bladder, delineated on each daily CT data set, were compared with those from the planning CT scan. Several quantities, including Dice's coefficient and the maximal overlapping rate, were used to characterize the interfraction variations. The delivered dose was reconstructed by applying the original plan to the daily CT scan with consideration of proper repositioning.Results: The mean prostate Dice's coefficient and maximal overlapping rate after bony registration was 69.7% +/- 13.8% (standard deviation) and 85.6% +/- 7.8% (standard deviation), respectively. The daily delivered dose distributions were generally inferior to the planned dose distribution for target coverage and/or normal structure sparing. For example, for approximately 5% of the treatment fractions, the prostate volume receiving 100% of the prescription dose decreased dramatically (15-20%) compared with its planned value. The magnitudes of the interfraction variations and their dosimetric effects indicated that, statistically, current standard repositioning using prostate alignment might be adequate for two-thirds of the fractions, but for the rest of the fractions, better on-line correction strategies, such as on-line replanning, are needed.Conclusion: Different adaptive correction schemes for prostatic interfraction changes can be used according to the anatomic changes, as quantified by the organ displacement and deformation parameters. On-line replanning is needed for approximately one-third of the treatment fractions. (C) 2011 Elsevier Inc.