Merrick G S, Butler W M, Dorsey A T, Lief J H, Benson M L
Schiffler Oncology Center, Wheeling Hospital, WV 26003-6300, USA.
Int J Radiat Oncol Biol Phys. 2000 Jan 1;46(1):215-20. doi: 10.1016/s0360-3016(99)00405-8.
Although postoperative dosimetric analyses of prostate brachytherapy are commonly reported, the long-term persistence, or fixity, of seeds implanted in the prostate gland and periprostatic region remains unclear, with only a few reports regarding the loss or migration of the seeds in the implanted region and none which correlate lung embolization to pelvic seed loss.
The study population consisted of 175 consecutive patients implanted with either 125I (95 patients) or 103Pd (80 patients) using a mean of 136 seeds in a modified uniform loading approach to cover a planning volume that was 1.64 times the ultrasound prostate volume. An average of 64% of 125I seeds were embedded in braided vicryl suture, and these seeds were used on the periphery and extra prostatic regions. Following CT-based dosimetric analysis on day 0, all patients had orthogonal plain films of the pelvis obtained from day 0 to day 502, with an average of 2.3 film pairs per patient. Routine diagnostic PA and lateral chest X rays were obtained for 156 patients over the same time period.
The mean pelvic seed fixity was greater than 98% throughout the time covered by this study. The seed fixity rates for 125I and 103Pd, although nearly equal, were significantly different up to 60 days post implant. The median 125I seed loss per patient was only 1 seed through 180 days while for 103Pd, the median seed loss was 2 seeds at 28 and 60 days and 3 seeds at 180 days. The fraction of patients experiencing no seed loss decreased from 40% at 28 days to 20% at 180 days for 125I and from 24% to 7% for 103Pd over the same time interval. Patient and treatment parameters closely correlated to local seed loss include the number of seeds implanted, the planning volume, and the number of loose seeds, and for 125I, the fraction of seeds in suture. The fraction of seeds placed outside the gland was not correlated with seed loss. Of the seeds lost from the pelvis, about 10% were found to embolize to the lungs. Among the 156 patients with post-implant chest X rays, the fraction of patients with pulmonary seed embolization was 34/156 (21.8%). Of the 20 patients who had post-implant chest X rays obtained within 14 days of brachytherapy, none had seeds detected in the lungs, while of the 136 patients who had chest X rays obtained greater than 30 days following implantation, 25.0% (34 patients) were noted to have seeds visualized in the lungs.
With a median follow-up of 9 months, 125I seeds embedded in a vicryl suture or 103Pd seeds can be safely implanted in the prostate and periprostatic tissue with a high probability of prostate bed seed fixity and a low incidence of radioactive seed embolization to the lungs.
虽然前列腺近距离放射治疗术后剂量学分析已有普遍报道，但植入前列腺及前列腺周围区域的粒子的长期留存情况，即固定性，仍不明确，关于植入区域粒子丢失或迁移的报道较少，且尚无将肺栓塞与盆腔粒子丢失相关联的报道。
研究人群包括175例连续接受植入治疗的患者，其中95例植入125I粒子，80例植入103Pd粒子，采用改良均匀布源法平均植入136颗粒子，以覆盖1.64倍超声前列腺体积的计划靶区。平均64%的125I粒子被包埋于编织的聚乙醇酸缝线中，这些粒子用于周边及前列腺外区域。在术后第0天进行基于CT的剂量学分析后，所有患者在术后0天至502天均拍摄盆腔正位平片，每位患者平均拍摄2.3对平片。同期为156例患者进行常规诊断性后前位和侧位胸部X线检查。
在本研究涵盖的整个时间段内，盆腔粒子的平均固定率大于98%。125I和103Pd粒子的固定率虽近乎相等，但在植入后60天内差异有统计学意义。每位患者125I粒子的中位丢失数在180天内仅为1颗，而对于103Pd粒子，在28天和60天时中位丢失数为2颗，在180天时为3颗。在相同时间间隔内，未出现粒子丢失的患者比例从125I粒子的28天时的40%降至180天时的20%，103Pd粒子则从24%降至7%。与局部粒子丢失密切相关的患者和治疗参数包括植入粒子数、计划靶区体积和松散粒子数，对于1·25I粒子，还包括缝线中粒子的比例。置于腺体外的粒子比例与粒子丢失无关。从盆腔丢失的粒子中，约10%被发现栓塞至肺部。在156例植入后进行胸部X线检查的患者中，肺部出现粒子栓塞的患者比例为34/156（21.8%）。在近距离放射治疗后14天内进行植入后胸部X线检查的20例患者中，肺部均未检测到粒子，而在植入后30天以上进行胸部X线检查的136例患者中，25.0%（34例）肺部可见粒子。
中位随访9个月，包埋于聚乙醇酸缝线中的125I粒子或103Pd粒子可安全植入前列腺及前列腺周围组织，前列腺床粒子固定概率高，放射性粒子肺栓塞发生率低。
