An experimental study regarding diagnostic accuracy on image interpretation of the digital image film by using viewboxes of different luminance

Objective To evaluate diagnostic accuracy of image interpretation using viewboxes at different luminance with ALVIM statistical phantom (TRG).Methods A digital film of TRG image was obtained by exposing the phantom of TRG with Kodak DR 3000 using proper parameter.Viewboxes with three different luminance were selected from those used in daily work.The film of TRG was evaluated with these viewboxes of three different luminance by three different radiologists with experience of five,eight and sixteen years respectively.A grade scale of 5 was used to evaluate each row of signal and noise.According to the results and formula,the probabilities of true-positive [P (S/s)],false-positive [P (S/n)] and true answer(Pdet) were obtained. Results The three kinds of luminance used in viewboxes were: (3489 ± 256),(2231 ± 220),(816 ± 168) cd/m2.When the average luminance of viewbox was 3489 cd/m2,Pdet of 0.6,0.7,0.8 mm in bone substitute was 0.558±0.009,0.788±0.008,0.813±0.006,Pdet of0.9,1.0,1.2 mm in muscle substitute was 0.663 ± 0.010,0.750 ± 0.008,0.933 ± 0.005 ; When the average luminance of viewbox was 2231 cd/m2 ,Pdet of 0.6,0.7,0.8 mm in bone substitute was 0.525 ± 0.013,0.713 ± 0.013,0.775 ± 0.016,Pdet of 0.9,1.0,1.2 mm in muscle substitute was 0.613 ± 0.019,0.650 ± 0.013,0.850±0.019 ;When the average luminance of viewbox was 816 cd/m2 ,Pdet of 0.6,0.7,0.8 mm in bone substitute was 0.475 ± 0.022,0.550 ± 0.018,0.688±0.020,Pdet of 0.9,1.0,1.2 mm in muscle substitute was 0.550 ± 0.025,0.575 ± 0.021,0.725 ± 0.016. Viewboxes of different luminance were compared to one another by paired t-test.The results of comparison all had significant statistical differences (t = 5.057 and 4.681 ,P <0.05).Conclusions The image displayed by viewboxes at different luminance had significant influence on image interpretation. The higher the luminace of viewbox,the richer the information displayed,and the higher the accuracy of diagnosis. Key words: Radiography;  Quality control;  Viewbox;  Luminance;  Diagnostic efficiency