Department of Physics, University of Alberta, Edmonton, Alberta, Canada.
J Appl Clin Med Phys. 2012 Jul 5;13(4):3753. doi: 10.1120/jacmp.v13i4.3753.
The purpose of this study is to evaluate the accuracy and precision of the Clarity 3D ultrasound system to track prostate gland positional variations due to setup error and organ motion. Seventeen patients (n = 17) undergoing radical external beam radiation therapy for localized prostate cancer were studied. Subsequent to initial reference ultrasound and planning CT scans, each patient underwent seven repeat weekly tracking CT and ultrasound (US) scans during the course of treatment. Variations in the location of the prostate between reference and tracking scans were measured. Differences reported by CT and ultrasound scans are compared. Ultrasound tracking was initially performed clinically by a group of trained general users. Retrospective prostate localization was then performed by a trained dedicated user upon the original raw data set and also a reduced data set derived from the original by an expert user from Resonant Medical. Correlation accuracy between ultrasound and CT shifts acquired and delineated by a pool of trained general users was deemed unacceptable for radiotherapy purposes. A mean discrepancy between CT and US localizations of greater than 10 mm, with a 5 mm or greater discrepancy rate of nearly 90%, was observed. Retrospective analysis by a dedicated user of both the original and Resonant Medical reduced data sets yielded mean CT-Us discrepancies of 8.7 mm and 7.4 mm, respectively. Unfortunately, the 5 mm or greater CT-US discord rate for these retrospective analyses failed to drop below 80%. The greatest disparity between CT and ultrasound was consistently observed in the superior-inferior direction, while greatest agreement was achieved in the lateral dimension. Despite an expert reanalysis of the original data, the Clarity ultrasound system failed to deliver an acceptable level of geometric accuracy required for modern radiotherapy purposes.
本研究旨在评估 Clarity 3D 超声系统在跟踪由于设置误差和器官运动导致的前列腺位置变化的准确性和精密度。研究了 17 名接受局部前列腺癌根治性外照射放射治疗的患者（n = 17）。在初始参考超声和计划 CT 扫描后，每位患者在治疗过程中接受了 7 次重复的每周跟踪 CT 和超声（US）扫描。测量参考和跟踪扫描之间前列腺位置的变化。比较 CT 和超声扫描报告的差异。最初由一组经过培训的普通用户进行超声跟踪。然后，由一名经过培训的专用用户对原始数据集进行回顾性前列腺定位，还由 Resonant Medical 的一名专家用户对原始数据集的简化数据集进行回顾性前列腺定位。在由一组经过培训的普通用户采集和勾画的超声和 CT 移位的相关性准确性方面，认为不适合用于放射治疗目的。观察到 CT 和 US 定位之间的平均差异大于 10mm，差异大于 5mm 的比例接近 90%。对原始数据集和 Resonant Medical 简化数据集的专用用户进行回顾性分析，分别得出 CT-US 差异的平均值为 8.7mm 和 7.4mm。不幸的是，对于这些回顾性分析，5mm 或更大的 CT-US 不相符率未能降至 80%以下。CT 和超声之间的最大差异始终出现在上下方向，而在侧向维度上达成了最大的一致性。尽管对原始数据进行了专家重新分析，但 Clarity 超声系统未能提供现代放射治疗所需的可接受的几何精度水平。
