Positron Emission Tomography/Computed Tomography (PECT/CT) Double-Scanning Study

Inclusion Criteria: * Must have a clinical indicated PET/CT exam scheduled including (but not limited to) one of the following radiopharmaceutical tracers: Fluorodeoxyglucose (FDG or 18F-FDG), 18F-DCFPyL; 68Ga- PSMA; 68Ga Dotatate; 18F Amyloid (18F- Florbetapir, 18F-Florbetaben, or 18F-Flutemetamol), or Other standard PET tracers; * Age ≥ 18 years old at time of consent; * Able to provide informed consent; AND, * Has the necessary mental capacity to understand instructions and is able to comply with protocol requirements. Exclusion Criteria: * Who, per the site's SOPs, has any condition that would prevent the clinically indicated PET/CT from proceeding (i.e., pregnancy, breastfeeding, renal impairment, elevated blood glucose, etc.); * Who were previously enrolled in this study; * Who need urgent or emergent care; * Who have any conditions that, in the opinion of the PI or designee, would interfere with the evaluation of the results, constitute a health hazard for the subject; * Unwilling to have GEHC personnel present during scans; OR, * Unable to tolerate the exam.