Less than 50% of patients receiving salvage radiation therapy (SRT) to the pelvis as treatment for prostate cancer relapsing after surgery will achieve undetectable Prostate Specific Antigen (PSA) levels. Despite SRT, two-thirds of patients will again develop elevated PSA, 20% will have distant metastases, and 10% will die from prostate cancer within 10 years. The reason for this is probably preexisting distant metastasis and lymph node metastasises which need to better targeted directly. Additionally , there are well known permanent side effects to SRT. Standard imaging techniques have poor sensitivity detecting recurrence when PSA is below 1.0 ng/ml. The surface protein Prostate-specific membrane antigen (PSMA) is overexpressed on prostate cancer cells and 68Gallium (68Ga)- and 18Fluorine (18F)-targeted radioligands have been developed. PSMA PET/CT is used increasingly but there is limited data of its impact. In this study patients with biochemical relapse of prostate cancer after surgery are randomised to the control or experimental group (1:2) and undergo a PSMA PET/CT scan. The experimental group receives individualised therapy based on the result of the PET/CT. The control group receives standard salvage therapy and the result of the PET/CT is blinded. The patients are followed-up with PSA test and quality of life questionnaires.