Stray radiation in the cardiac catheterisation laboratory.

Staff radiation risk is related to the radiation field in which individuals work. Traditional protective measures focus on reducing stochastic risk. However, deterministic injury to the operator's hands cannot always be ignored. The stray radiation field is almost totally attributable to scatter from the patient. Its relative intensity is greatest near the entry port of the useful beam into the patient. The entry port moves during the procedure as the operator selects various required projections. Therefore, the relative exposure rate at any particular location in the laboratory changes with the clinical projection. The absolute scatter intensity is also dependent on the size and strength of the useful beam. Operators may put their hands near or in the useful beam. Leaded surgical gloves provide some overall finger protection for scatter fields. However, because of automatic dose rate controls, these gloves often increase risk when the operator's hands are seen on the image monitor.