Since the photon energy of positron emitting radionuclides is significantly higher than the maximum kVp of diagnostic x rays, designing a shielding plan for a PET/CT imaging facility requires careful consideration of future workloads and potential occupancy of surrounding spaces. The shielding calculations can be done by hand or with the aid of available software. In calculating the shielding, specific considerations arise. Some of these are presented as a checklist of things to consider when preparing to calculate the shielding required for a PET/CT facility.