Seed-displacements in the Immediate Post-Implant Phase in Permanent Prostate Brachytherapy.
Radiotherapy and oncology(2023)
摘要
Purpose: To investigate differences in seed-displacements between the immediate post-implant phase (day 0-1) and the time to post-plan computed tomography (CT) (day 1-30) in seed prostate brachyther-apy.Materials and methods: Seed positions were identified on the intra-operatively created ultrasound-based treatment plan (day 0) and CT scans of day 1 and 30 for 33 patients. The day 1 (30) seed arrangement was registered onto the day 0 (1) arrangement using a seed-only approach. Based on a 1:1 assignment of seeds via the Kuhn-Munkres algorithm, seed-displacements were analyzed. Displacements were evalu-ated depending on strand-length and anatomical implant location. Resulting dosimetric effects were cal-culated.Results: Seed-displacements in the immediate post-implant phase (median displacements: 3.8 +/- 3.6 mm) were stronger than in the time to post-plan CT (2.1 +/- 2.6 mm) and enhanced along the superior-inferior direction. From day 0 to 1, strands containing one (7.3 +/- 5.4 mm) or two (8.1 +/- 5.8 mm) seeds showed larger displacements than strands of higher lengths (up to 4.2 +/- 7.0 mm), whereas no length -dependency was found to day 30. Seeds implanted in base and apex tended to move towards the prostate midzone during both time periods. D90 (dose that 90% of prostate receives) was with variations of 2 +/- 15 Gy more stable from day 1 to 30 than in the immediate post-implant phase (-18 +/- 11 Gy).Conclusion: Seed-displacements in the immediate post-implant phase was enhanced compared to day 1- 30. This may result from uncertainties in the gold-standard ultrasound-based treatment planning and implantation. Adaptive implantation workflows appear useful for ensuring high implant stability from the beginning.(c) 2023 Elsevier B.V. All rights reserved. Radiotherapy and Oncology xxx (2023) xxx-xxx
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关键词
Seed brachytherapy,Permanent implant,Prostate cancer,Seed displacements,Prostate brachytherapy,Adaptive implantation
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