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Updated: Aug 21, 2026
Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
Multicenter ProKnow-based plan evaluation of postprostatectomy salvage radiotherapy patients using SPPORT and
Michael Keilholz1,2, Erik F Moar3, Frederike Brose3,4
1Department of Radiation Oncology, LMU University Hospital, LMU Medizin, Ludwig-Maximilians-Universität München, Munich, Germany. Michael.Keilholz@med.uni-muenchen.de.
Purpose:
Salvage radiotherapy (sRT) after radical prostatectomy is the only curative treatment for patients with biochemical recurrence. Sparing organs at risk (OAR) is essential to minimize long-term toxicity. This multicenter study analyzed radiotherapy plans from Bavarian university centers within the Bavarian Cancer Research Center (BZKF) using dose-volume constraints from the SPPORT and RADICALS-HD trials.
Methods:
In this retrospective multicenter analysis, 117 patients treated with prostate bed sRT were included. Radiotherapy plans were anonymized and evaluated using ProKnow (Elekta, Stockholm, Sweden). Scorecards based on SPPORT and RADICALS-HD dose-volume constraints were used to assess plan quality. Planning metrics, including planning target volume (PTV), D95, conformality index, and V66, were recorded, and their correlations with OAR dose were analyzed.
Results:
The median PTV was 213.9 cm3 (interquartile range [IQR] 154.4-267.8 cm3), with a median D95 of 64.5 Gy (IQR 63.7-67.1 Gy). The median volume receiving 66 Gy (V66) was 192.62 cm3 (IQR 146.59-244.49 cm3). Bladder dose constraints were met in 92-100% of plans according to RADICALS-HD and in 89-97% according to SPPORT. Rectal constraints were fulfilled in 98-100% and 95-100% of plans, respectively. All femoral head plans met the SPPORT V50 constraint. Correlation analyses showed weak associations with bladder dose and weak-to-moderate associations with rectal dose.
Conclusion:
This multicenter analysis demonstrates that dose-volume objectives in the postoperative salvage setting can be reliably assessed across centers and are met in the majority of cases. ProKnow enables structured and objective plan evaluation and serves as a useful tool for standardized quality assurance.