Department of Radiation Oncology, Sydney Cancer Centre, NSW, Australia.
Radiother Oncol. 2011 Dec;101(3):490-4. doi: 10.1016/j.radonc.2011.08.004. Epub 2011 Aug 31.
HDR brachytherapy is used as a conformal boost for treating prostate cancer. Given the large doses delivered, it is critical that the volume treated matches that planned. Our outpatient protocol comprises two 9 Gy fractions, two weeks apart. We prospectively assessed catheter displacement between CT planning and treatment delivery.
Three fiducial markers and the catheters were implanted under transrectal ultrasound guidance. Metal marker wires were inserted into 4 reference catheters before CT; marker positions relative to each other and to the marker wires were measured from the CT scout. Measurements were repeated immediately prior to treatment delivery using pelvic X-ray with marker wires in the same reference catheters. Measurements from CT scout and film were compared. For displacements of 5mm or more, indexer positions were adjusted prior to treatment delivery.
Results are based on 48 implants, in 25 patients. Median time from planning CT to treatment delivery was 254 min (range 81-367 min). Median catheter displacement was 7.5mm (range -2.9-23.9 mm), 67% of implants had displacement of 5mm or greater. Displacements were predominantly caudal.
Catheter displacement can occur in the 1-3h between the planning CT scan and treatment. It is recommended that departments performing HDR prostate brachytherapy verify catheter positions immediately prior to treatment delivery.
高剂量率近距离放射治疗（HDR 近距离放疗）被用作治疗前列腺癌的适形增敏放疗。由于治疗中使用了大剂量，因此确保治疗体积与计划一致至关重要。我们的门诊方案包括两个 9Gy 剂量分次，间隔两周。我们前瞻性地评估了 CT 计划与治疗实施期间的导管移位情况。
在经直肠超声引导下植入三个基准标记物和导管。在 CT 前，将金属标记线插入 4 根参考导管中；从 CT 扫描中测量标记物之间以及标记物与标记线之间的相对位置。在治疗实施前，使用带有标记线的骨盆 X 射线立即重复测量，标记线位于相同的参考导管中。比较 CT 扫描和 X 射线片上的测量值。对于 5mm 或以上的移位，在治疗实施前调整定位器位置。
结果基于 25 名患者的 48 个植入物。从计划 CT 到治疗实施的中位时间为 254 分钟（范围 81-367 分钟）。导管的中位移位为 7.5mm（范围-2.9-23.9mm），67%的植入物的移位为 5mm 或以上。移位主要是尾侧的。
在计划 CT 扫描和治疗之间的 1-3 小时内，导管可能会发生移位。建议行 HDR 前列腺近距离放疗的科室在治疗实施前立即验证导管位置。
