The goal of this study is to demonstrate that Photon Counting CT (PC-CT) creates similar or better-quality pictures of the body compared to CT systems we currently use in the clinic. The department of Radiology will be conducting this study using the new PC-CT system at MUSC for imaging of the head, neck, and blood vessels. Participants in this study will receive their normally ordered imaging scan as well as an additional imaging scan on the PC-CT machine. This second scan will take place within a month following the first normally ordered imaging study. This additional scan will be the only extra visit for this research study. Risks are the same as a typical CT scan which can include radiation dose, IV dye allergies, risks from IV, and potential loss of confidentiality.