Portable TL dosemeter--ESD phantom combination for chest and lumbar spine radiography

Abstract

A thermoluminescence dosemeter (TLD)-entrance surface dose (ESD) phantom combination was calibrated in terms of air-kerma in IEC RQR X-ray radiation qualities between 50 and 150 kV. The ESD phantom was designed and constructed as a part of the work. With the combination, air-kermas were measured for four radiological examinations (two chest and two lumbar spine examinations in two hospitals), and converted to ESDa using Monte-Carlo calculated BSF data tabulated for different tube voltages, filtrations and beam diameters at 1 m distance. The results agreed with the ionisation-chamber measurements within the reported overall uncertainty of the TLD method. In the calibration, the ESD phantom can be replaced by the ISO water slab phantom unaffecting the reported overall uncertainty. Backscatter-related parameters for the ISO water slab phantom and the newly designed ESD phantom were determined for the IEC RQR qualities used in the secondary standard dosimetry laboratory of STUK at 1 m distance, including an approximate Hp(10)/Hp(0.07) ratio.