Estimation of the efficacy of protective coats in abdominalangiography

Abstract

The risk of occupational exposure in abdominal angiography is reported to be high due not only to direct radiation, but also stray radiation from inspection tables, patients, the image intensifier, the beam limiting system (collimator), etc. The Japanese standard JISZ4831 prescribes protective coats of at least 0.25 mm lead equivalent and is the uniform thickness of lead equivalent. The most commonly used protective coats are 0.25, 0.35, or 0.5 mm in thickness. The weight of a typical protective coat is about 3 kg. While there are coats that weigh up to 6 kg, wearing such heavy coats becomes physically burdensome as inspection time increases. The trade-off between physical burden and protection was considered by measuring the X-ray intensity distribution and attenuation rate of stray radiation in each position assumed by the medical staff. In the case of inspections performed at an x-ray tube voltage of 80 kV, it may be possible to reduce the weight of the lead rubber apron by about 33 percent because the lead thickness is reduced uniformly when shielding capability of a 0.25 mm thick Pb layer is accepted as the standard at 40 cm above the gonad position. The reduction in weight was feasible, even from a managerial perspective, because the increase in the dose rate is only about 0.01 mGy/min at 110 kV, whereas the intensity is about 1.5 times higher than at 80 kV.