Abstract:
The Entrance Skin Dose (ESD) for common radiographic examinations of forty (40) patients was measured prospectively at the Benue State University Teaching Hospital, Makurdi using LiF thermo-luminescent dosimeter (TLD) chips. The examination comprised ten (10) patient’s each of chest, abdomen, pelvic and lumbar sacral regions.The mean ESDs obtained by LiF TLD for Chest X-ray (PA), Plain Abdomen, Lumbar Spine (AP) and Pelvic (AP) were 0.50 mGy, 0.20 mGy, 0.80 mGy, 0.70 mGy respectively. The mean ESDs determined by mathematical formulae of Edwin and McCoullough (1970), Edmonds (1984), Arun Kumar et al. (1991), Chougule and Hussain (1993) and Pratik Kumar et al. (1996) for Chest X-ray were 0.50 mGy, 0.80 mGy, 0.30 mGy, 0.30 mGy and 0.60 respectively. The mean ESDs for Plain Abdomen byEdwin and McCoullough (1970), Edmonds (1984), Arun Kumar et al. (1991), Chougule and Hussain (1993) and Pratik Kumar et al. (1996) were found to be 3.00 mGy, 5.00 mGy, 2.00 mGy, 1.70 mGy, 4.00 mGy respectively. The mean ESDs for Lumbar Sacral by Edwin and McCoullough (1970), Edmonds (1984), Arun Kumar et al. (1991), Chougule and Hussain (1993) and Pratik Kumar et al. (1996) were 8.00 mGy, 11 mGy, 5.00 mGy, 4.00 mGy, 8.00 mGy respectively and the mean ESDs for Pelvic X-ray (AP) by Edwin and McCoullough (1970), Edmonds (1984), Arun Kumar et al. (1991), Chogule and Hussain (1993) and Pratik Kumar et al. (1996) were found to be 2.00 mGy, 3.00 mGy, 1.30 mGy, 1.20 mGy, 3.00 mGy respectively.The comparison between the calculated and the measured values using paired samples test and Bland-Altman plots showed that there was a wide variation between the two methods except for the chest X-ray examinations in which the significant (2-Tailed) values were more than 0.05, showing that, the statistical difference between the calculated and the measured ESD in the chest X-ray examinations is not significant (p > 0.05). Therefore, Edwin and McCullough, 1970; Edmonds, 1984; Arun Kumar et al., 1991; Chougule and Hussain, 1993 and Pratik Kumar et al., 1996 formulae can be used to calculate the ESDs of chest X–ray examinations. The ESDs of the examined parts obtained by the use of mathematical formulae and the use of LiF TLD were found to be relatively low when compared to international standards and some literatures in this work. Apparently, radiation risk to patients and workers are minimized in accordance to the ALARA principle (As Low As Reasonably Achievable). The ESDs determined by mathematical formulae and LiF TLDs increased with increase in kVp.
