Can a better scan sharpen radiation for prostate cancer?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adenocarcinoma of the prostate, post radical-prostatectomy * Detectable prostate-specific antigen (PSA) * Eastern Cooperative Oncology Group (ECOG)/Zubrod performance status of 0-2 * No definitive findings for skeletal metastasis on technetium 99-m methyl diphosphonate (MDP) or F-18 PET bone scan * No definitive findings of systemic (extrapelvic) metastasis on CT and/or magnetic resonance (MR) scan of abdomen and pelvis * Willingness to undergo pelvic radiotherapy Exclusion Criteria: * Contraindications to radiotherapy (including active inflammatory bowel disease or prior pelvic radiotherapy) * Inability to undergo fluciclovine or Ga-PSMA PET-CT * Definitive findings of systemic metastasis on conventional imaging or biopsy * Prior invasive malignancy (except non-melanomatous skin cancer) unless disease free for a minimum of 3 years * Severe acute co-morbidity, defined as follows: * Unstable angina and/or congestive heart failure requiring hospitalization in the last 3 months * Transmural myocardial infarction within the last 6 months * Acute bacterial or fungal infection requiring intravenous antibiotics at the time of registration * Chronic Obstructive Pulmonary Disease exacerbation or other respiratory illness requiring hospitalization or precluding study therapy at the time of registration * Acquired immune deficiency syndrome (AIDS) based upon current Center for Disease Control (CDC) definition; note, however, that human immunodeficiency virus (HIV) testing is not required for entry into this protocol. The need to exclude patients with AIDS from this protocol is necessary because the treatments involved in this protocol may be significantly immunosuppressive. Protocol-specific requirements may also exclude immunocompromised patients