Assessment of the occupational eye lens dose in pediatric interventional cardiology

Background: The International Commission of Radiation Protection recommended a new dose equivalent limit of 20 mSv per year for occupational exposure in planned situations, averaged for a defined period of 5 years.Aim: The main aim of this study is to simulate examinations of a catheterization laboratory and to determine the eye lens dose which is received by medical staff at the University Hospital Graz at the Department for Interventional Pediatric Cardiology in Graz. The second aim is to determine, whether a dosimeter which is worn at the height of the thorax, could be used as measurement device for the eye lens dose.Material and Methods: To determine the eye lens dose for the medical staff (person1-3), phantom measurements were carried out. The preparations included the decision of optimal position of the used dosimeters, the measurement set up and the estimation of a ratio between the eye lens dose measured with a Hp(0.07) and Hp(3) calibrated dosimeter. Results and Discussion: Depending on staff position, absence of protection devices like lead glasses and ceiling suspended shield, as well as the thorax height of the patient it can be concluded that person 1 (near the X-ray tube) would exceed the annual dose limit of 20 mSv. Person 2 would exceed the limit, if only patients with a thoracic height of 20 cm would be examined. The dose values for person 3 (nurse position) were generally much lower. The documented correction coefficients between the equivalent doses of the lens of the eye measured at collar and eye lens level lie in a range of 0.7 to 1.0, depending on the position of the staff members. Regarding the phantom size, it could be determined that with increasing thoracic height of the patients, an increasing eye lens dose results. A change in frame rates (for the cine mode), has a minor effect on the eye lens dose. A higher dose of up to 87-99% is the result of change in fluoroscopy mode from low to high. From setting normal to high the dose increases 2