The Measurement of Entrance Surface Air Kerma for Digital Radiography Using OSL NanoDot™ Dosimeter

Abstract

The assessment of entrance skin air kerma (ESAK) from radiographic examination can be performed either the calculation method recommended by International Atomic Energy Agency report no. 457, or the direct measurement using a dosimeter. The aims of this study were to measure the values of ESAK using NanodotTM dosimeter and compare those with the calculation method and to measure doses for eye lens, thyroid gland and breast received from the examination. The six of most common radiographic examinations were performed using an adult female phantom. The routine exposure parameters used for the hospital were set. The results revealed that the values of ESAK for skull anteroposterior (AP) and lateral cross table, the chest posteroanterior (PA), Aabdomen supine (AP) and upright (AP) and the pelvis AP were 1.51, 1.51, 0.16, 7.69, 1.33 and 8.03 milligray (mGy), respectively. The percentage differences between both methods were within ±16.88% the maximum doses for the eye lens, breast and thyroid gland received from the examinations were 1.52, 1.78 and 0.87 mGy, respectively. The values of ESAK from the measurement using NanodotTM were lower than those from the calculation method. This was because the axis of nanodotsTM was not perpendicular to the x-ray beam. The measured and calculated ESAKs for the skull and chest radiographs obtained in this study were lower than the dose level recommended by the department of medical sciences, Thailand but those for the abdomen and pelvis were higher. The exposure techniques can be further reviewed by the hospital authority in order to reduce doses for patients