Risk assessment from bitewing radiography

The effective dose equivalent and the effective dose from bitewing radiography have been estimated for three different X-ray sets under 10 different exposure conditions using the ICRP 26 (1977) and the ICRP 60 (1990) recommendations. The results of dose measurements in the head and neck with an Alderson Rando phantom and thermoluminescence dosimeters (TLD-100 ribbons) were used (Velders XL et al. Dentomaxillofac Radiol 1991; 20: 161-5). The effective dose equivalent (ICRP 26) was calculated using the salivary glands and brain as remainder organs. The highest effective dose equivalent was 11 microSv for the Philips Oralix 50 unit with a round, pointed cone; the lowest was 2 microSv for the X-ray sets with a rectangular open-ended tube. The highest effective dose using the ICRP 60 weighting factors was 4 microSv for the Oralix 50, the lowest 1 microSv for the X-ray sets with a rectangular open-ended tube. The probability of stochastic effects was calculated as at the most 0.18 x 10(-6) using a nominal probability coefficient of 165 x 10(-4) Sv-1 (ICRP 26); when using the ICRP 60 recommendations (where the nominal probability coefficient for stochastic effects including non-fatal cancer is 730 x 10(-4) Sv-1) the maximum probability was 0.25-0.31 x 10(-6). The maximum probability of fatal cancer induction was calculated as 0.18 x 10(-4) for both fatal probability coefficients, 125 x 10(-4) Sv-1 in ICRP 26 and 500 x 10(-4) Sv-1 in ICRP 60. The calculated probability of the total stochastic effects is nearly twice as high when using the new recommendations, whilst the estimated probability of fatal cancer induction is of the same order of magnitude with both.