Purpose. The search for ways to minimize the harmful effects of ionizing radiation on the population during the digital radiography of the chest PA, including screening.

Materials and methods. The study was conducted on KARS-BKS2 slot-scan digital low-dose fluorograph using a special object consisting of a contrast sensitivity test (CST) plate and a spatial resolution test plate placed behind a water phantom simulating an average patient. Dose control was carried out by an Unfors Xi dosimeter. Digital x-ray image quality was assessed using MEDARM and Microsoft Excel.

Results. Objective image quality indicators (programmatically calculated) of the special object are obtained for a series of images recorded for a set of values of the anode voltage and the x-ray tube current. It is proposed to use the signal-to-noise ratio of the digital image of the CST plate as a quality indicator. The range of optimal settings of anode voltage and current providing images of certain quality at the lowest doses is determined.

Conclusions. A method for objective assessment of digital image quality in terms of the signal-to-noise ratio for the CST plate image is proposed. The visibility of the thinnest plate corresponding to 0.5% contrast sensitivity is assumed to be high image quality. Optimal acquisition modes of chest PA images using  KARS slot-scan digital fluorograph were determined which provide high-quality 420×420 mm images at a minimum entrance surface dose of 124 µGy (corresponds to an effective dose of 0.024 mSv according to methodological guidelines MU 2.6.1.2944-11).

The proposed method of objective assessment of digital image quality can be used to determine the optimal acquisition modes of chest PA images for digital radiography machines to minimize the radiation exposure of patients.