Dipartimento di Fisiopatologia Clinica, Universita' degli Studi di Firenze, Firenze, Italy.
Med Phys. 2013 Jan;40(1):011710. doi: 10.1118/1.4769428.
The aim of this paper is to investigate the accuracy of a laser∕camera surface imaging system (Sentinel) when used on patients treated in the thorax or pelvic regions and to evaluate system employment conditions and patient setup procedures that provide more accurate results.
The system was tested on two groups of patients for whom different patient setup procedures and Sentinel employment conditions were considered. For the first group of 33 patients (FG) no changes to the usual setup procedures were made and a surface extension limited to the treated region was considered. For the second group of 14 patients (SG) the reproducibility of external body surfaces, including body parts not in close proximity to the treatment site, was optimized and a wider surface was captured. In all cases the system accuracy was evaluated comparing registration results from concurrent Sentinel and cone beam CT (CBCT) acquisitions for a total of 192 occasions. External body surfaces, extracted from planning CT studies, were used as reference in both cases, but for SG also surface data captured by Sentinel system at the first treatment were employed.
In the 90th percentile of the distributions reporting CBCT and Sentinel registration parameters, absolute differences for FG were less than 6.4 mm and 3.8°. Better performances were observed for SG (≤5.7 mm and 2°). Mean absolute differences between three translation and three rotation parameters of CBCT and Sentinel were: less than 3.5 mm and 2.1° and 3.7 mm and 1.3° in FG for thorax and pelvis, respectively, and less than 2.8 mm and 1° and 2.7 mm and 0.9° for pelvis and thorax, respectively, in SG. No advantage in considering surface data captured by Sentinel as a reference instead of the surface extracted from the planning CT was observed.
The accuracy of Sentinel system in detecting errors is influenced by the extension and reliability of the surface used. When the reproducibility of external body surfaces was optimized differences between CBCT and Sentinel registration parameters resulted less than 5.7 mm and 2° in the 90% of the pelvis and thorax considered cases. No advantage in considering a Sentinel acquisition as reference was observed.
本文旨在研究激光/相机表面成像系统（Sentinel）在胸部或盆腔区域治疗患者时的准确性，并评估提供更准确结果的系统使用条件和患者设置程序。
该系统在两组患者中进行了测试，考虑了不同的患者设置程序和 Sentinel 使用条件。对于第一组 33 名患者（FG），未对常规设置程序进行更改，并考虑了仅治疗区域的表面扩展。对于第二组 14 名患者（SG），优化了包括远离治疗部位的身体部位在内的外部身体表面的可重复性，并捕获了更宽的表面。在所有情况下，通过比较总共 192 次 Sentinel 和锥形束 CT（CBCT）同时采集的注册结果来评估系统的准确性。在两种情况下，均使用从计划 CT 研究中提取的外部身体表面作为参考，但对于 SG，还使用了 Sentinel 系统在第一次治疗时捕获的表面数据。
在报告 CBCT 和 Sentinel 注册参数的 90 百分位数分布中，FG 的绝对差异小于 6.4mm 和 3.8°。对于 SG，观察到更好的性能（≤5.7mm 和 2°）。对于胸部和骨盆，FG 的 CBCT 和 Sentinel 的三个平移和三个旋转参数之间的平均绝对差异分别小于 3.5mm 和 2.1°和 3.7mm 和 1.3°，对于骨盆和胸部，SG 分别小于 2.8mm 和 1°和 2.7mm 和 0.9°。没有观察到将 Sentinel 捕获的表面数据用作参考而不是从计划 CT 提取的表面数据的优势。
Sentinel 系统检测误差的准确性受所使用表面的扩展和可靠性的影响。当优化外部身体表面的可重复性时，在考虑的骨盆和胸部病例的 90%中，CBCT 和 Sentinel 注册参数之间的差异小于 5.7mm 和 2°。没有观察到将 Sentinel 采集用作参考的优势。
