What is the primary purpose of a blank scan in PET?

The primary purpose of a blank scan in PET is to set uniform sensitivity for detector modules. In PET imaging, a blank scan is conducted to establish a baseline measurement for the system's performance without any radiopharmaceutical present. This helps to calibrate the detectors so that they can accurately detect and quantify the radiation emitted from the radioactive tracers during patient scans. By ensuring that each detector module has consistent sensitivity, the resulting images will be more reliable and reproducible, which is essential for accurate diagnostics and assessments.

While the other options mention important aspects of PET imaging, they do not accurately capture the primary function of a blank scan. Measuring patient radiation exposure, creating 3D models, and improving image resolution are all significant factors in the overall imaging process, but they do not directly relate to the specific objective of establishing a standardized sensitivity across the detector system through a blank scan.