Entrance surface dose of eyes and thyroid using nanoDot optically stimulated luminescence in 64-slices computed tomography scanner

Abstract

Entrance surface dose (ESD) is used to estimate the patient exposure dose during X-ray computed tomography (CT) procedures. However, in a clinical practice the ESDs measurements remains challenging due to lack of suitable dosimeters. We demonstrated an anthropomorphic phantom ESDs assessment for both eyes and thyroids; left and right using Landauer nanoDot™ OSL dosimeters (OSLDs) during 64-slices CT scan examinations. 24 nanoDot™ OSLDs were randomly selected and placed within slices 1 to 9 of anthropomorphic phantom. The ESDs were measured through direct energies (80-140 kV) and variation of current value (minimum, middle and maximum) from CT scanner model Siemens Somatom Definition AS+. We found that this practical method using small OSLDs; have an outer width of 10 mm can measured a partial dose from selective CT protocols. The ESDs results for both eyes and thyroids from 2 different InLight Microstar OSL reader show that the doses increased by the changes of energies and current values. For readout procedure using InLight Microstar OSL reader, standard measurement (in 30 days) evaluated from the dark current (DRK), CAL and LED counts were found rightly below the control limits of 30 (DRK), and ±10% of the mean (CAL and LED). In conclusion, nanoDot™ OSLDs is considered as potential candidate for direct measurement of entrance surface dose of patient.