Virginia Commonwealth University Health System, Department of Radiation Oncology, 401 College St., Richmond, VA 23298.
Georgetown University, 3700 O St NW, Washington, DC 20057.
Brachytherapy. 2021 Jul-Aug;20(4):771-780. doi: 10.1016/j.brachy.2021.03.011. Epub 2021 May 14.
Implanted fiducial markers are a commonly used tool in delineating the CTV in high-dose-rate interstitial brachytherapy (HDR-ISBT) for gynecologic malignancy, but their reliability in gynacological sites is not well understood. These markers and interstitial applicators can experience interfractional motion due to organ swelling or other anatomical changes. The purpose of this study was to evaluate the spatial variation of these features.
The spatial positions of 50 implanted markers and 202 needles were tracked in 15 patients treated over 70 fractions of HDR brachytherapy. Marker and/or needle coordinates were extracted from CT images with contours and dose distributions. Automated analysis determined marker self-consistency and displacements between various elements of the implant.
From start to end fraction, the relative positions of the markers experienced an average magnitude displacement of 4.5 ± 3.0 mm while the average displacement of the applicator tips was 11 ± 8 mm, relative to their respective centers of mass (CM).
Markers implanted lateral and superior to the CTV experience greater drift than other implant locations.
在用于妇科恶性肿瘤的高剂量率间质近距离治疗（HDR-ISBT）中，植入的基准标记物是用于勾画临床靶区（CTV）的常用工具，但人们对其在妇科部位的可靠性了解甚少。这些标记物和间质施源器可能会因器官肿胀或其他解剖结构变化而发生分次间运动。本研究旨在评估这些特征的空间变化。
在 15 名接受超过 70 次 HDR 近距离治疗的患者中，跟踪了 50 个植入标记物和 202 根针的空间位置。从 CT 图像中提取标记物和/或针的坐标，以及轮廓和剂量分布。自动分析确定了标记物的自一致性以及植入物各个元件之间的位移。
从起始分次到结束分次，标记物的相对位置经历了 4.5±3.0mm 的平均幅度位移，而施源器尖端的平均位移为 11±8mm，相对于它们各自的质心（CM）。
与其他植入部位相比，植入于CTV 外侧和上方的标记物会发生更大的漂移。
