The correct thickness of lead-equivalent (Pbeq) wear will depend on how long and how often the person is working in an exposed environment. The minimum requirement is to wear 0.25 mm Pbeq when not behind lead shielding. In a theatre using fluoroscopy (e.g. orthopaedics, cardiology or interventional radiology) 0.35 or 0.5 mm lead may be appropriate because of the higher KV employed, and on proximity to the primary beam.