Here is the design of a clinical trial:

Official Title: PSMA-PET Guided Hypofractionated Salvage Prostate Bed Radiotherapy of Biochemical Failure After Radical Prostatectomy for Prostate Cancer

Included conditions:
- Prostate Cancer
- Cancer Recurrence

Study Armgroups:
- {'label': 'Conventional', 'type': 'ACTIVE_COMPARATOR', 'description': 'Conventional sEBRT', 'interventionNames': ['Radiation: Conventional sEBRT']}
- {'label': 'Hypofractionation', 'type': 'EXPERIMENTAL', 'description': 'Hypofractionated sEBRT', 'interventionNames': ['Radiation: Hypofractionated sEBRT']}

Interventions:
- {'type': 'RADIATION', 'name': 'Conventional sEBRT', 'description': 'A total dose of70 Gy in 35 daily fractions of 2 Gy during 7 weeks', 'armGroupLabels': ['Conventional'], 'otherNames': ['Conventional salvage external beam radiation therapy']}
- {'type': 'RADIATION', 'name': 'Hypofractionated sEBRT', 'description': 'A total dose of 60 Gy in 20 daily fractions of 3 Gy during 4 weeks', 'armGroupLabels': ['Hypofractionation'], 'otherNames': ['Hypofractionated salvage external beam radiation therapy']}

Primary Outcomes:
- {'measure': '5-year progression-free survival', 'description': 'Defined as biochemical progression, clinical progression, loco-regional or distant progression or start with hormonal therapy, whichever occurs first', 'timeFrame': '5 years'}

Please estimate the sample size based on the assumption: 
Alpha of 5%, study power of 81%, and a dropout rate of 12%.
Sample size considerations
        A systematic review and meta-analysis reported that each additional Gy in the conventional sEBRT-arm is possibly associated with a 2% higher bPFS, independent of other factors. These results imply that our biological dose escalated effect with hypofractionation will result in 16% higher bPFS (8âGyâÃâ2% per Gy). However, this meta-analysis did not include series using a radiotherapy dose above 70âGy. In higher dose series as proposed in this study, the relative benefit may be lower and consequently an expected benefit of 16% may be too optimistic. Therefore, a conservative 12% higher 5-year bPFS in the experimental arm of 20 fractions of 3âGy compared to the conventional sEBRT schedule of 35 fractions of 2âGy (70âGy) has been chosen. This estimated benefit of 12% is also supported by a meta-analysis including conventional and hypofractionated regimens addressing the influence of fraction size and the total dose effect on bPFS and toxicity [28].
        The results of the GETUG-AFU 16 trial showed a 5-year bPFS of 62% with the conventional fractionated radiotherapy protocol [26]. We used this percentage (62%) for the 5-year bPFS in our conventional sEBRT treatment arm. Following the above mentioned literature, we hypothesize that with the experimental regimen the bPFS can be improved from 62 to 74%. Using an alpha of 5% and a study power of 81%, the required sample size is 235 participants per treatment arm. Assuming a dropout of 12%, we need to recruit 269 participants per treatment arm: 538 in total.