An off-line strategy for constructing a patient-specific planning target volume in adaptive treatment process for prostate cancer
An off-line strategy for constructing a patient-specific planning target volume in adaptive treatment process for prostate cancer
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DOI：
10.1016/s0360-3016(00)00608-8
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发表时间：
2000-08-01
影响因子：
7
通讯作者：
Martinez, A
中科院分区：
文献类型：
--
作者：
Yan, D;Lockman, D;Martinez, A
目的：为了提高前列腺癌体外放射治疗的剂量传递和剂量递增的效果，在自适应放射治疗过程中，利用目标位置和患者设置位置的图像反馈，建立了一种基于患者特异性规划靶体积的离线策略。材料和方法：我们假设存在患者特异性置信度限制计划靶体积（cl-PTV），该计划靶体积使用每日内部靶运动和患者设置误差的初始测量序列构建，并确保前列腺癌患者的临床靶体积（CTV）在预定义的剂量耐受范围内接受规定剂量。首先使用前k天CT测量的凸包构造患者特定的边界体积来校正目标位置并补偿目标随机运动。边界体积和CT测量的初始天数根据预定义的剂量学标准最小化。通过模拟对30名前列腺癌患者进行常规4场盒和调强放疗（IMRT）的实际治疗，使用每日多个CT图像对该假设进行了验证。对于每个患者，还将患者特定的设置边界应用于边界体积，以形成最终的cl-PTV。这个余量是用门脉成像测量最初几天预测的随机设置误差和校正系统设置误差后的残差来确定的。结果：在治疗的第一周，使用每日CT测量构建的边界体积足以使常规光束传输达到处方剂量的最大剂量减少2%或更少，至少80%的患者（p = 0.08）， 95%的患者（p = 0.1）减少4.5%或更少。然而，对于IMRT给药，需要2周的每日CT测量才能达到相似的剂量学标准水平，否则CTV的最大剂量平均减少7%。此外，为了保持相同的剂量学标准，IMRT治疗所需的患者特异性设置余地至少是常规治疗的两倍。与传统的PTV相比，cl-PTV的体积显着减少，同时保持相同的剂量学标准。结论：利用影像学测量的反馈，可在治疗第1周内建立前列腺癌的cl-PTV。cl-PTV具有排除系统变化和补偿患者在目标位置和患者设置位置上的随机变化的能力。这意味着在目前的离线图像反馈自适应治疗过程中，可以在治疗的第二周内进行单次计划修改，以提高前列腺癌外束治疗的剂量传递和剂量递增效果。(C) 2000 Elsevier Science Inc.；
Purpose: To improve the efficacy of dose delivery and dose escalation for external beam radiotherapy of prostate cancer, an off-line strategy for constructing a patient-specific planning target volume is developed in the adaptive radiotherapy process using image feedback of target location and patient setup position.Materials and Methods: We hypothesize that a patient-specific confidence-limited planning target volume (cl-PTV), constructed using an initial sequence of daily measurements of internal target motion and patient setup error, exists and ensures that the clinical target volume (CTV) in the prostate cancer patient receives the prescribed dose within a predefined dose tolerance. A patient-specific bounding volume to correct for target location and compensate for target random motion was first constructed using the convex hull of the first k days of CT measurements. The bounding volume and the initial days of CT measurements were minimized based on a predefined dosimetric criterion. The hypothesis was tested using multiple daily CT images by mimicking the actual treatment of both conventional 4-field-box and intensity-modulated radiotherapy (IMRT) on each of 30 patients with prostate cancer. For each patient, a patient-specific setup margin was also applied to the bounding volume to form the final cl-PTV. This margin was determined using the random setup error predicted from the initial days of portal imaging measurements and the residuals after correcting for the systematic setup error.Results: The bounding volume constructed using daily CT measurements in the first week of treatment are adequate for the conventional beam delivery to achieve maximum dose reduction in the CTV of 2% or less of the prescription dose, for at least 80% of patients (p = 0.08), and 4.5% or less for 95% of patients (p = 0.1). However, for IMRT delivery, 2 weeks of daily CT measurements are required to achieve a similar level of the dosimetric criterion, otherwise the maximum dose reduction of 7%, on average, in the CTV is expected. Furthermore, the patient-specific setup margin required for the IMRT treatment is at least twice larger than that for the conventional treatment, to maintain the same dosimetric criterion. As compared to the conventional PTV, the volume of cl-PTV is significantly reduced, while maintaining the same dosimetric criterion.Conclusion: The cl-PTV for prostate treatment can be constructed within the first week of treatment using the feedback of imaging measurements. The cl-PTV has the capability to exclude the systematic variation and compensate for the patient-specific random variation on target location and patient setup position. This implies that in the current off-line image feedback adaptive treatment process, a single plan modification can be performed within the second week of treatment to improve the efficacy of dose delivery and dose escalation for external beam therapy of prostate cancer. (C) 2000 Elsevier Science Inc.