PSMA PET/CT扫描是术后生化复发前列腺癌的标准成像程序，由于其在低血清PSA水平下的高检出率。然而，现有的前列腺床保存性外部放射治疗（sEBRT）的临床靶区体积（CTV）指南主要基于经验性临床共识，并使用传统成像技术进行验证。因此，本研究旨在通过利用PSMA PET/CT检测到的局部复发（LR）来优化sEBRT中的CTV定义。在荷兰的9个中心中，对术后疑似LR的患者进行了回顾性纳入。匿名扫描由专家核医学医师进行中央审查。评估并调整了Groupe Francophone de Radiothérapie en Urologie（GFRU）CTV指南的每个边界，以改善于PSMA PET/CT上所发现的LR（CTV）的精确度和覆盖范围。关于CTV适应的建议已与参与中心的放射肿瘤学医师进行讨论，并达成最终共识。为了评估再现性，要求参与中心依据新的PERYTON-CTV划定三个新病例的轮廓，并使用Dice相似系数（DSC）进行评估。经中央审查后，在83个PSMA PET/CT中共发现了93个LR。与GFRU-CTV相比，建议的CTV定义将PSMA PET/CT检测到的LR的覆盖率从67%提高至96%，同时减少了GFRU-CTV体积25%。新的CTV具有很高的再现性，平均DSC为0.82（范围：0.81至0.83）。本研究通过利用PSMA PET/CT上检测到的LR模式，对术后前列腺床sEBRT的CTV定义进行了优化。PERYTON-CTV在参与中心间具有高度的再现性，并确保96%的LR的覆盖，同时减少了GFRU-CTV的体积25%。版权所有 © 2023. Elsevier Inc.发表

PSMA PET/CT scan is the standard imaging procedure for biochemical recurrent prostate cancer post-prostatectomy due to its high detection rate at low serum PSA levels. However, existing guidelines for clinical target volume (CTV) in prostate bed salvage external beam radiation therapy (sEBRT) are primarily based on experience-based clinical consensus and have been validated using conventional imaging modalities. Therefore, this study aimed to optimize CTV definition in sEBRT by utilizing PSMA PET/CT-detected local recurrences (LRs).Patients with suspected LR on PSMA PET/CT post-prostatectomy were retrospectively enrolled in nine Dutch centers. Anonymized scans were centrally reviewed by an expert nuclear medicine physician. Each boundary of the CTV guideline from the Groupe Francophone de Radiothérapie en Urologie (GFRU) was evaluated and adapted to improve the accuracy and coverage of the area at risk of LR (CTV) on PSMA PET/CT. The proposed CTV adaptation was discussed with the radiation oncologists of the participating centers, and final consensus was reached. To assess reproducibility, the participating centers were asked to delineate three new cases according to the new PERYTON-CTV, and the submitted contours were evaluated using the dice similarity coefficient (DSC).After central review, 93 LRs were identified on 83 PSMA PET/CTs. The proposed CTV definition improved the coverage of PSMA PET/CT-detected LRs from 67% to 96% compared to the GFRU-CTV, while reducing the GFRU-CTV volume with 25%. The new CTV was highly reproducible with a mean DSC of 0.82 (range: 0.81 to 0.83).This study contributes to the optimization of CTV definition in post-prostatectomy sEBRT by using the pattern of LR detected on PSMA PET/CT. The PERYTON-CTV is highly reproducible across the participating centers and ensures coverage of 96% LRs while reducing the GFRU-CTV volume with 25%.Copyright © 2023. Published by Elsevier Inc.