Correlation between scatter radiation dose at height of operator's eye and dose to patient for different angiographic projections

Studies have reported cases of radiation-induced cataract among cardiology professionals. In view of the evidence of epidemiological studies, the ICRP recommends a new threshold for opacities and a new radiation dose to eye lens limit of 20 mSv per year for occupational exposure. The aim of this paper is to report scattered radiation doses at the height of the operator's eye in an interventional cardiology facility without considering radiation protection devices and to correlate these values with different angiographic projections and operational modes. Measurements were taken in a cardiac laboratory with an angiography X-ray system equipped with flat-panel detector. PMMA plates of 30×30×5 cm were used with a thickness of 20 cm. Measurements were taken in two fluoroscopy modes (low and normal, 15 pulses/s) and in cine mode (15 frames/s). Four angiographic projections were used: anterior posterior; lateral; left anterior oblique caudal (spider); and left anterior oblique cranial, with a cardiac protocol for patients weighing between 70 and 90 kg. Measurements of phantom entrance dose rate and scatter dose rate were performed with two Unfors Xi plus detectors. The detector measuring scatter radiation was positioned at the usual distance of the cardiologist's eyes during working conditions. There is a good linear correlation between the kerma area product and scatter dose at the lens. Experimental correlation factors of 2.3, 12.0, 12.2 and 17.6 μSv/Gy cm2 were found for different projections. PMMA entrance dose rates for low and medium fluoroscopy and cine modes were 13, 39 and 282 mGy/min, respectively, for AP projection.