Study of Low Dose Exposure Condition and Image Quality with Chest Computed Radiography / 医疗卫生装备

ABSTRACT

Objective To investigate the best exposure condition for reducing the radiation dose of the chest radiography and obtaining the good quality of images. Methods With different tube voltage (kVp), tube current & time (mAs), and focus-film distance(FFD) adopted, X-ray detecting phantom was exposed by means of automatic exposure control(AEC). The dosage absorbed in skin was detected; Spatial resolution capacity, low contrast resolution capacity and low contrast sensitive degree were tested. The space and density resolution capacity were tested. The chest image quality was appraised by the way of visual observation and the measure of film density. Results The different kVp and FFD were related to the emitting skin dose (ESD), the higher kVp and the farther FFD follows the lower ESD; the higher or lower mAs has no effect on the image resolution capacity , but it had effect on image noise. The density value and seeing effect of chest film with low dose had reached good image density and needs of diagnostics. Conclusion Under the condition of 120 kVp high voltage, FFD150cm, AEC reduced density and adjusting to the processing parameters of the CR chest images, the radiation dosage of the chest computed radiography can be reduced efficiently and the good quality of images can be obtained.