This clinical trial examines RefleXion Medical Radiotherapy System (RMRS) imaging to the standard of care (SOC) [18F]-DCFPyL positron emission tomography-computed tomography (PET-CT) imaging in patients with prostate cancer. PET is an established imaging technique that utilizes small amounts of radioactivity attached to very minimal amounts of a tracer, [18F]-DCFPyL, that binds to prostate specific membrane antigen (PSMA) on tumor cells. These PSMA tumor cells can then be identified on PET imaging. CT utilizes x-rays that traverse body from the outside. CT images provide an exact outline of organs and potential inflammatory tissue where it occurs in patient's body. The RMRS is a imaging-therapy combination system that can plan for and deliver radiation therapy as well perform [18F]-DCFPyL PET-CT imaging. Comparing the imaging from the standard of care [18F]-DCFPyL-PET-CT with the [18F]-DCFPyL imaging from RMRS may help improve the quality of the imaging captured and determine if imaging can be done on the RMRS at the same time as planning for radiation therapy, which would reduce the number of scans needed to plan for radiation for prostate cancer.

PRIMARY OBJECTIVE:

I. To assess imaging performance of the fluorine F 18 piflufolastat ([18F]-DCFPyL) PET-CT subsystem on the X1 RMRS to detect lesions (primary and metastatic) in patients with prostate cancer.

SECONDARY OBJECTIVE:

I. To determine the feasibility of generating a biology-guided radiotherapy (BgRT) plan using X1 RMRS-acquired [18F]-DCFPyL PET data derived from the imaging-only session at the studied dose level.

OUTLINE:

Patients receive [18F]-DCFPyL intravenously (IV) and undergo [18F]-DCFPyL PET-CT over 30 minutes per standard of care (SOC). Patients with PET avid lesions then undergo a X1 RMRS PET-CT imaging-only session within 120 minutes of injection over 20-35 minutes.

After completion of study, patients are followed up within 72 hours.

Inclusion Criteria:

• Documented informed consent of the participant and/or legally authorized representative
• Age >= 21 years
• Patients undergoing SOC [18F]-DCFPyL PET-CT
• Patients should be scheduled for [18F]-DCFPyL PET-CT prior to study entry

Exclusion Criteria:

• Known psychiatric or substance abuse disorder that would interfere with conduct of the study
• Patient weight exceeding the weight limit (450 pounds) outlined per X1 RMRS specifications sheet

Adverse events were collected from the beginning of the imaging-only session on the X1 RMRS system and continued until 72 hours after the end of the scan.