Effect of radiation protection apron defect on radiation dose during fluoroscopy

Occupational exposure should be minimised to a level that is as low as reasonably achievable. Radiation protection aprons and thyroid collars are effective in reducing occupational radiation dose as they typically attenuate at least 90% of scattered radiation. However, cracks and holes may compromise the shielding capacity of the apron. The aim of the study was to quantify change in radiation dose behind defects to support the development of rejection criteria for damaged aprons. Air kerma rates were measured with a calibrated solid-state dosimeter behind a 0.25 mm Pb-equivalent apron containing seven circular defects (diameter 1.5-20 mm) and one horizontal crack (50 mm) under two clinical fluoroscopy settings and compared with measurements obtained behind an intact apron. The air kerma rate increased by up to 165µGy h^-1behind the damaged apron. Based on average annual fluoroscopy times per operator at Kuopio University Hospital, the use of damaged apron could result in an annual air kerma increase of 9.7 mGy behind the damaged area. Defect size and location affect the shielding performance of protective aprons. Considering defect position in rejection criteria allows more realistic estimation of the potential impact on staff effective dose and helps avoid unnecessary replacement of protective garments. Based on the present measurements, defects smaller than approximately 1 cm did not produce a meaningful increase in air-kerma values under the tested conditions.