Abstract: ［Abstract］〓Objective〖HTSS〗〓To explore an operable digital radiography(DR) lowdose examination method.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓A total of 500 patients who underwent chest DR examination were enrolled. The patients were divided into 5 groups according to their chest thickness. Group A(body thickness H≤20 cm) 100 cases, group B(body thickness H＞20-22 cm)110 cases, group C(body thickness H＞22-25 cm )100 cases, group D(body thickness H＞25-27 cm)90 cases, group E(body thickness H>27 cm)100 cases. A, B, C, D and E were randomly divided into manual control group A1 group(50 cases), B1 group(55 cases), C1 group(50 cases), D1 group(45 cases), E1 group(50 cases). Automatic exposure control(AEC) group A2 group(50 cases), B2 group(55 cases), C2 group(50 cases), D2 group(45 cases), E2 group(50 cases). Manual control group exposure conditions are A1 group 102 kV/0.8 mAs, B1 group 109 kV/0.8 mAs, C1 group 117 kV/0.8 mAs, D1 group 125 kV/0.8 mAs, E1 group 133 kV/1 mAs, AEC group exposure conditions are 125 kV/0.7-3 mAs, other imaging parameters are the same. The radiation dose was measured by a dosimeter. Quality scoring and noise evaluation were performed for each image. For all chest radiographs, the right upper lung field, beneath edge of diaphragm, and background exposure area were measured for optical density.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓The average radiation dose of group A1, B1, C1, D1 and E1 was significantly lower than that of A2, B2, C2, D2 and E2 groups, and the difference was statistically significant(P＜005). There was no significant difference in the image quality score, noise evaluation, and chest Xray density between the manual control group(A1, B1, C1, D1 and E1) and the AEC group(A2, B2, C2, D2 and E2)(P＞005).
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓In the chest DR examination, the radiation dose received by the patient is significantly reduced by setting the exposure conditions and optimizing the exposure parameters according to the patient′s chest thickness, and the image quality can still be guaranteed, so this method is worth of promotion.

Key words: radiography, thorax, low dose