The effect of beam tube potential variation on gonad dose to patients during chest radiography investigated using high sensitivity LiF : Mg,Cu,P thermoluminescent dosemeters

Optimization of X-ray beam tube potential (kVp) in radiological examination s can minimize patient dose. This research aims to investigate the effect o f tube potential variation on gonad doses to patients during posteroanterio r (PA) chest radiography examinations. This study was carried out using a T oshiba general purpose X-ray unit and a Rando phantom, Dose measuring equip ment included an ion chamber system, a dose-area product (DAP) meter and a thermoluminescent dosemeter (TLD) reader system with high sensitivity TLD p ellets of LiF:Mg,Cu,P for low level gonad dose measurement. PA chest exposu res of the phantom to produce a constant exit dose were made using a standa rd low tube potential (range 60-100 kVp) non-grid technique and a high tube potential (lange 95-150 kVp) grid technique. Entrance surface doses (ESDs) and DAPs were also included in the measurements. Effective doses (EDs) wer e computed from ESD and DAP measurements using NRPB-SR262 and Xdose softwar e. Results show that with the low tube potential technique both ovary dose and testes dose increase with increasing tube potential; statistically sign ificant correlations of r=0.994 (p=0.0006) and r=0.998 (p=0.001), respectiv ely, were found. For both organs, doses increase at a rate of approximately 2% per kVp. With the high tube potential technique there is insignificant correlation between gonad doses and tube potential. When comparing patient doses from typical exposures made at 70 kVp (low tube potential non-grid te chnique) with doses from exposures made at 120 kVp thigh tube potential gri d technique), the high tube potential technique delivers significantly high er values for ESD, and ovary, testes and effective doses by factors of 1.7, 5.2, 5.5 and 2.7, respectively.