Stereotactic Re-irradiation of Local Recurrences of Prostate Cancer After Radiotherapy

"Salvage SBRT will be performed in three subgroups of patients with local recurrence:~Group A - after conventionally fractionated/moderately hypofractionated definitive radiotherapy; Group B - after prostatectomy and postoperative radiotherapy; Group C - after ultrahypofractionated definitive SBRT~Target volumes:~GTV- tumour visible on MRI and PET-CT; CTV- 1-3 mm margin around GTV PTV- 3 mm around CTV\*~\*- in cases in which very high accuracy and reproducibility of SBRT are ensured, and the margin overlaps the rectum and/or bladder, it is possible to reduce the margin from these organs to 1 mm.~Dose constrains:~The criteria for limiting the dose in nearby organs are not well-defined for repeated irradiation - the following doses should be aimed:~* Maximum rectal dose ≤103% of the prescribed dose (optimal ≤100%)~* Maximum bladder dose ≤105% of the prescribed dose (optimal ≤103%)~Dose-volume constrains:~Rectum:~• D30% \<15Gy~Bladder:~• D30% \< 15 Gy"