Estimation of effective dose equivalent to staff in diagnostic radiology

Abstract

The irradiation of staff in diagnostic radiology was simulated for conditions commonly encountered in fluoroscopy. Scattered radiation distributions were produced from diagnostic x-ray beams generated at tube potentials in the range 60-120 kVp, using the abdomen sections of a Rando phantom. Doses to a number of organs in the head and neck were measured using a Rando phantom loaded with lithium fluoride thermoluminescent dosemeters. The torso sections were placed on a water phantom on top of a stand, with film badge dosemeters positioned on the surface of the phantom at the forehead, neck, chest and waist, and the phantom was placed in the radiation field. Doses to organs in the torso were calculated from the waist-level film badge dosemeter reading using normalised organ dose data. Radiation doses to organs below a lead apron, when worn, were estimated from the unshielded dose values using a transmission factor appropriate to the quality of the scattered radiation. The effective dose equivalent (EDE) to the phantom was calculated for various x-ray beam qualities and lead apron thicknesses and compared with the film badge doses. The results indicate that a dosemeter worn at the waist/chest level under a lead apron generally underestimates the EDE. Conversely, dosemeters worn at the forehead/neck tend to overestimate the EDE. It is recommended that a dosemeter is positioned under a lead apron, if worn.