| Περίληψη: | A seven month dose survey, from October 2018 to April 2019, was performed with 364 adult patients, who underwent 5 of the most common diagnostic X–ray examinations, including 7 individual projections: chest postero–anterior (PA), chest lateral (LAT), abdomen PA, pelvis AP, lumbar spine AP, lumbar spine LAT as well as kidneys and urinary bladder (KUB) AP. All the patients (146 females and 218 males) were underweight as they all had BMI less than 18.50 Kg/m^2. In this inquiry, a radiation dose survey on low BMI patients during digital radiographic examinations performed at the radiology department of the university hospital of Patras was made. Calculation of the patients’ entrance surface air kerma (ESAK) was made with an indirect method employing the X-ray tube output and the exposure parameters while the estimation of effective dose (ED) was carried out making use of suitable effective dose per unit KAP coefficients. The institutional doses were established at the 75th percentile of the distribution of ESAK and KAP values. In addition, a comparison of the dosimetric quantities between underweight and normal patients was made utilizing the results from a recently published article. Mann-Whitney test demonstrated a statistically significant decrease in KAP, ESAK and ED values, for all examinations studied, for low BMI patients compared to normal patients. Concerning the gender of the patients, a statistically significant decrease was not found in the radiation dose values when male patients compared to female patients. The percentage decrease for chest PA, chest LAT, abdomen PA, lumbar spine AP, lumbar spine LAT, pelvis AP and KUB AP in underweight patients was 40%, 39%, 48%, 68%, 57%, 46% and 68% for median KAP, 26%, 46%, 51%, 48%, 19%, 44% and 53% for median ESAK, as well as 33%, 46%, 46%, 67%, 58%, 47% and 67% for median ED values, respectively. The corresponding institutional doses for underweight patients were 0.065 mGy, 0.349 mGy, 0.683 mGy, 1.54 mGy, 3.922 mGy, 1.111 mGy, 0.668 mGy and 0.042 Gycm2, 0.218 Gycm2, 0.45 Gycm2, 0.28 Gycm2, 0.598 Gycm2, 0.597 Gycm2, 0.267 Gycm2 in terms of ESAK and KAP values, respectively. It can be concluded that underweight patients received a significantly reduced radiation dose compaired to normal patients. The estimated patient doses could be used as a baseline in other X–ray departments to evaluate their local practice, but additional audits need to be conducted for this patient group that will further contribute towards optimization of patients’ radiation protection in diagnostic radiography.
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