Patient dosimetry in abdominal arteriography.

This study aims at accurate quantification of x-ray exposure and effective dose to the patient in abdominal arteriography. Using an automatic monitoring system, all relevant exposure parameters were determined during 172 abdominal arteriographies. Common projections were extracted for a 'normal' reference group of procedures and used in Monte Carlo calculations of dose-area product to organ dose conversion coefficients. Dose-area product, organ doses and effective dose were quantified for intravenous and intra-arterial procedures. The large data sets describing exposure could be condensed to a set of 28 common views. New coefficients to convert dose area product to organ equivalent dose and effective dose were calculated for nine views contributing approximately 80% to the total dose-area product. The average dose-area product was 32 Gy cm2 in intravenous procedures and 47 Gy cm2 in intra-arterial procedures. The corresponding average effective doses to the patient were 4 mSv and 6 mSv respectively (range 2-12 mSv, actual value depending on procedure type and gender). It is concluded that automatic monitoring of x ray exposure parameters, complemented by the calculation of Monte Carlo organ dose conversion coefficients, is a feasible and promising approach to accurate dosimetry of complex arteriographic procedures.

Effectiveness of lead aprons in vascular radiology: results of clinical measurements.

PURPOSE: To determine the effectiveness of 0.5-mm-thick lead-equivalent aprons in vascular radiology. MATERIALS AND METHODS: The radiation dose to radiology personnel was measured under and over lead aprons in more than 100 patient examinations. Thermoluminescent dosimeters of high and normal sensitivities (detection levels of 1 and 10 microGy, respectively) were used. Dose measurements in clinical practice were complemented with real-time measurement of generating potential, dose-area product, and fluoroscopy time. In addition, measurements of the radiation attenuation of aprons were performed in simulated exposure conditions. The generating potential in fluoroscopy--weighted for the contribution to the occupational exposure--varied between about 70 and 95 kV per examination (average, 78 kV). RESULTS: On the basis of measurements obtained under clinical conditions in vascular radiology, attenuation factors between 70 and 280 were derived. The typical radiation attenuation factor for 0.5-mm-thick lead-equivalent aprons was 200. CONCLUSION: The effectiveness of 0.5-mm-thick lead-equivalent aprons, determined with clinical measurements, agrees with estimates based on generating potential. Previously published effective doses, inferred from nonclinically determined radiation transmission factors, probably overestimate the actual dose levels.

Vascular radiology in The Netherlands in 1992: a quantitative approach.

A survey was held into methods and extent of vascular radiology in the Netherlands. For the year 1992, quantitative data on the number of patients, vascular radiological examinations and characteristics of angiography facilities were obtained from more than 80% of the Dutch hospitals with angiography rooms (120). The following estimates have been inferred: approximately 50,600 patients were referred for non-cardiac vascular radiology, including 32,100 patients for intra-arterial arteriography, 8900 for intravenous DSA arteriography, 4600 for phlebography and 5000 for interventional radiology. On average about two vascular examinations were carried out per patient referred for arteriography. In interventional radiology, the number of patients and the number of examinations are quite similar. The total number of angiography rooms in the Netherlands was 136. The average age of angiography X-ray systems was 7.1 years, of imaging equipment 5.7 years. In 56% of the hospitals, the X-ray tube was normally applied in the undercouch position, in 40% in overcouch position and in 4% there was no preferred position. An additional survey of occupational exposure conditions in angiography rooms (19 hospitals) showed that, in most hospitals, protective lead aprons of 0.5 mm Pb-equivalent were in use. Thyroid collars were used rather infrequently.

Dose estimates for exposure to radioactivity in gas mantles.

In this paper dose estimates are given for internal and external exposure that result, due to radioactive thorium, from the use of the incandescent mantles for gas lanterns. The collective, effective dose equivalent for all users of gas mantles is estimated to be about 100 Sv per annum in the Netherlands. For the population involved (ca. 700,000 persons) this is roughly equivalent to 5% to 10% of the collective dose equivalent associated with exposure to radiation from natural sources. The major contribution to dose estimates comes from inhalation of radium during burning of the mantles. A pessimistic approach results in individual dose estimates for inhalation of up to 0.2 mSv.