Positron Emission Tomography (PET) takes advantage of emissions from the decay of radioactive materials (e.g., radiotracers) to precisely locate and visualise physiological processes. Single-photon emission computed tomography (SPECT) uses a more direct way of measuring the emitted gamma rays, resulting in a broader range of usable isotopes at the expense of some resolution. Both PET and SPECT are typically paired with CT to co-locate radiotracers with anatomical features.