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Purpose: The primary aim of this retrospective multicenter analysis was to assess the performance of PSMA PET/CT using [18F]DCFPyL in the detection and localization of recurrent prostate cancer post radical prostatectomy (RP). Particular reference is given to low PSA groups < 0.5 ng/mL to aid discussion around the inclusion of this group in PSMA guidelines and funding pathways. Methods: Retrospective analysis of combined PSMA database patients from centers in Australia and New Zealand. Two hundred twenty-two patients presenting with recurrence post RP were stratified into five PSA groups (ng/mL): 0–0.19, 0.2–0.49, 0.5–0.99, 1–1.99, and ≥ 2. Lesions detected by [18F]DCFPyL PET/CT were recorded as local recurrence, locoregional nodes, and metastases. Results: Of 222 patients, 155 (69.8%) had evidence of abnormal uptake suggestive of recurrent prostate cancer. The detection efficacies for [18F]DCFPyL PET/CT were 91.7% (44/48) for PSA levels ≥ 2 ng/mL, 82.1% (23/28) for PSA levels 1–1.99 ng/mL, 62.8% (27/43) for PSA levels 0.5–0.99 ng/mL, 58.7% (54/92) for PSA levels 0.2–0.49 ng/mL, and 63.6% (7/11) for PSA levels ≤ 0.2 ng/mL. In those with PSA < 0.5 ng/mL, 47.6% (49/103) had detectable lesions, 71.4% (35/49) had disease confined to the pelvis, 22.4% (11/49) had prostate bed recurrence, 49.0% (24/49) had pelvic lymph nodes, and 28.6% (14/49) had extra pelvic disease. Conclusion: [18F]DCFPyL PET/CT has a high detection rate in recurrence following RP even at low PSA levels with similar detection levels in the PSA subgroups < 0.5 ng/mL. Employing rigid PSA thresholds when constructing guidelines for PSMA PET/CT funding eligibility may result in a significant number of patients below such thresholds having delayed or inappropriate treatment. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this retrospective study was to investigate the use of a radiopaque tissue fiducial marker (TFM) in the treatment of prostate cancer patients who undergo post-prostatectomy radiotherapy (PPRT). TFM safety, its role and benefit in quantifying the set-up uncertainties in patients undergoing PPRT image-guided radiotherapy were assessed. Purpose: The aim of this retrospective study was to investigate the use of a radiopaque tissue fiducial marker (TFM) in the treatment of prostate cancer patients who undergo post-prostatectomy radiotherapy (PPRT). TFM safety, its role and benefit in quantifying the set-up uncertainties in patients undergoing PPRT image-guided radiotherapy were assessed. Materials and Methods: A total of 45 consecutive PPRT patients underwent transperineal implantation of TFM at the level of vesicourethral anastomosis in the retrovesical tissue prior to intensity-modulated radiotherapy. Prostate bed motion was calculated by measuring the position of the TFM relative to the pelvic bony anatomy on daily cone-beam computed tomography. The stability and visibility of the TFM were assessed in the initial 10 patients. Results: No postoperative complications were recorded. A total of 3,500 images were analysed. The calculated prostate bed motion for bony landmark matching relative to TFM were 2.25 mm in the left-right, 5.89 mm in the superior-inferior, and 6.59 mm in the anterior-posterior directions. A significant 36% reduction in the mean volume of rectum receiving 70 Gy (rV70) was achieved for a uniform planning target volume (PTV) margin of 7 mm compared with the Australian and New Zealand Faculty of Radiation Oncology Genito-Urinary Group recommended PTV margin of 10 mm. Conclusion: The use of TFM was safe and can potentially eliminate set-up errors associated with bony landmark matching, thereby allowing for tighter PTV margins and a consequent favourable reduction in dose delivered to the bladder and rectum, with potential improvements in toxicities. [ABSTRACT FROM AUTHOR]