Correlation analysis of the estimated ESD in routine x-ray diagnostic procedures at a local level in Bosnia and Herzegovina

Health centers in small towns in Bosnia and Herzegovina do not have DAP facility or TLD equipment so that the estimation of entrance surface doses (ESD) could be performed merely from Tube Output Measurements. The goal of this work is to evaluate ESD at a local level in X-routine diagnostic radiology procedures for standard adult patient, including correlation analysis and comparison the results obtained with the recommended diagnostic reference levels. In a small health center such as the Banovici Health Center in the Tuzla Canton, the measurements were focused to high-frequency X-ray examinations: chest (PA) and lumbar spine (AP, Lat). The results obtained indicate that the deviations between ESD values of two radiologists employed in the Banovici Health Center are mostly due to very large exposure time during the examinations done by the one of radiologists. The value of cross-correlation coefficient between the ESD for chest PA examination of -0.75 indicates that one data set has a negative linear relationship to another data set. A histogram of the result, obtained by the bootstrap procedure establishing the uncertainty of the quantity, represents strong quantitative evidence that both ESD data set are negatively correlated. Also, the correlation coefficients of 0.12 and 0.41, for the LS examination in PA and LAT projections, respectively, do not indicate strong linear relation between data set of both radiologists. It was performed ANOVA for comparing the means of two radiologists data set for the chest AP examination. The very small value of p=1.09*10-7 indicates that differences between the two chest ESD results are highly significant. However, p-values of 0.17 and 0.35 obtained for LS-examinations in AP and LAT projections, respectively, suggest that the sample means are not significantly different. The results indicate that adequate measures should be taken for the benefit of the patients. (author)