Experimental study of correlation between entrance surface dose(ESD) of phantom and detection of pulmonary lesion in CR

Objective To assess the correlation between the entrance surface dose(ESD) of phantom and detection of simulated pulmonary lesion,and to explore the optimization of exposure dose for computed radiography(CR).Methods Simulated reticular,linear,and nodular structures were located in an anthropomorphic chest phantom.The images of chest phantom were taken at different exposure dose group for the CR system.One hundred and forty volunteers were exposed with different doses,standard chest posteroanterior CR images were gathered.Four radiologists assessed all of the images.In addition,the ESD was measured.Results The high dose group(exposure index from 1 900 to 2 100) ensured a high image quality with detail detectability.CR images obtained at the medium dose group(exposure index from 1 500 to 1 800) were obscure in the tiny nodular structure(diameter6mm).CR images with medium dose setting was lower than that of with high dose setting in detection reticular and linear structures.However,the difference did not reach significance(P0.05).CR images obtained at the low dose group(exposure index from 1 000 to 1 400) were low image contrast.low dose setting led to significantly decreased diagnostic performance in overall lesion detection.Conclusion Radiation injuries may effectively decrease reducing exposure dose level under the precondition of CR image quality to be guaranteed.The exploration of exposure dose optimization for CR imaging must consider correlative factors.