RESUMO
Objective To investigate the influence of tube voltage on image quality and radiation dosage to subjects in chest digital radiography (DR).Methods An adult chest phantom was exposed in the range of 80-130 kV with the interval of 10 kV and the automatic exposure control (AEC) setting was selected from-4 to 4.The entrance skin dose (ESD) of the phantom was measured,and the relative noise,contrast-to-noise ratio (CNR) and the effective dose of each exposure was calculated.Results The ESD was (0.062 9 ±0.027 4) mGy,and the effective dose was (0.012 7 ±0.004 5) mSv.The effective dose increased linearly with the ESD,and there was a positive correlation (r =0.912,P ＜ 0.01).When the tube voltage was held constant,the relative noise decreased as the effective dose increased (r =-0.967,-0.969,-0.968,-0.969,-0.968,-0.970,P ＜ 0.01).The CNR increased with the effective dose increasing under the same tube voltage(r =0.987,0.987,0.986,0.987,0.988,0.989,P ＜0.01).The ESD and effective dose decreased as the kV values increased under the same AEC,and the degree of decrease could be up to 50％ and 20％.The relative noise decreased as the kV values increased under the same AEC,and the degree of decrease could be up to 23％.The CNR values increased up to 8％.Conclusions The use of higher kVp in chest digital radiography can reduce the radiation dose to some extent