Effective doses in chest and abdominal radiography following the ICRP recommendations of 1991 and 2007 in a regional hospital.

Abstract

Background: In 2007, the International Commission for Radiological Protection (ICRP), published a new set of tissues and tissue weighting factors as recommendations in the ICRP publication 103. This altered the parameters contributing to the calculation of effective dose, which is normally used as a single indicator of risk. Purpose: To assess the effect of the 2007 review of tissue weighting factors on measured doses in a clinical setting, using patient doses for chest (CXR) and abdominal (AXR) radiography. Materials & Methods: Patient entrance surface doses(ESD) obtained in a dose audit for chest (CXR) and abdomen (AXR) examinations with Harshaw type Lithium Fluoride thermoluminescent dosemeters (LiF-TLD 100) were used in a Monte Carlo calculation software, XDOSE, developed by the National Radiation Protection Board (NRPB) to calculate organ doses. Effective doses (E mSv) were calculated with both the ICRP 1991 and 2007 recommendations of tissue weighting factors. A 2-sample t-statistic was used to test for differences between the results for both recommendations. Tests were at the 95% confidence interval. Results: The mean effective doses for CXR were found to be 0.04 (range 0.019 to 0.092) mSv and 0.03 (range 0.011 to 0.069) mSv for the 1991 and 2007 recommendations, respectively. Mean abdominal effective dose values were 0.78 (range 0.16 to 2.98) mSv for the 1991 wƮ factors, and 0.49 (range 0.099 to 1.97) mSv for the 2007 recommended factors. The mean percentage difference between the effective doses calculated with wƮ recommendations of 1991 and 2007 respectively came to 1.7 ± 0.6 % with a range between 0.8 and 3.3 % for CXR (p < 0.05) and 35.9 ± 5.6 with a range of 20.8 to 42.3%, for AXR (p = 0.05). Conclusion: Effective doses showed statistically significant differences between the values calculated from the 1991 and 2007 wƮ values for chest radiography. There is however, insufficient evidence to accept a difference for the abdominal effective doses. Wider studies are required to confirm this result.