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BACKGROUND AND OBJECTIVE: Digital systems have been replacing with screen-film analogue systems in diagnostic radiology departments, rapidly. Despite the differences in the properties of new x-ray imaging detectors, the same radiographic protocols that had been used for radiographic film-screen are used for digital imaging systems, without any review yet. In this study, the image quality and the patient dose in digital imaging of the chest are evaluated and optimized. METHODS: Two digital radiography machines from two separated hospitals (Imam Khomeini and Bu Ali Hospitals-Sari) have been used in this experimental research. Imaging and dose measurement are carried out at different source to phantom distances and kilo-voltages. For measurement of the image quality, a contrast-detail radiography (CDRAD) phantom is used. For evaluation of optimization, the Inverse Image Quality Figure per patient dose squared (IQFinv/E2) is used. FINDINGS: Evaluation of measured data for optimization shows that for both of these two digital radiography machines, despite of increasing in patent dose, with reducing of kilo-voltage, the IQFinv/E2 is increased. The maximum values of this parameter for Imam Khomeini and Bu Ali Hospitals are measured 0.0180 and 0.0083, respectively. CONCLUSION: The results of this study indicate that despite the traditional notion of using higher kilo-voltages for chest radiography, with increasing kilo-voltage, the ratio of image quality per patient dose is reduced. So, for optimization of chest radiography, as much as possible the kilo-voltage should be reduced based on the size of patient and clinical purpose.

• Background: The present study aimed to determine and compare the frequency distribution of chest radiographic views in patients with smear positive and smear negative pulmonary tuberculosis (TB). • Methods: In this cross-sectional study, 142 files of patients with smear positive and smear negative pulmonary tuberculosis were carried-out. We evaluated the demographic data, sputum acid-fast staining result and chest radiography of patients and recorded the results involving the region and the type of the lung involvement. Then, the collected data were analyzed. • Finding: The mean age of the patients was 46.46 ± 20.51; 60 patients (42.3%) were men and 82 (57.7%) were women. In addition, 53 patients (37.3%) were Iranian and 89 (62.7%) were Afghani. From 142 patients, 81 (57%) were smear positive and 61 (43%) were smear negative. The mean age (P = 0.51), sex distribution (χ2 = 1.68; P = 0.2) and the nationality distribution (χ2 = 0.38; P = 0.38) were not different between smear positive and smear negative patients. There was not any significant difference between the region (χ2 = 0.94; P = 0.8) and the type (χ2 = 12.88; P = 0.12) of the lung involvement, too. • Conclusion: Based on the results of this study, there was no difference between smear positive and smear negative patients in terms of chest radiography findings.

Background: The present study aimed to determine and compare the frequency distribution of chest radiographic views in patients with smear positive and smear negative pulmonary tuberculosis (TB). Methods: In this cross-sectional study, 142 files of patients with smear positive and smear negative pulmonary tuberculosis were carried-out. We evaluated the demographic data, sputum acid-fast staining result and chest radiography of patients and recorded the results involving the region and the type of the lung involvement. Then, the collected data were analyzed. Finding: The mean age of the patients was 46.46 ± 20.51; 60 patients (42.3%) were men and 82 (57.7%) were women. In addition, 53 patients (37.3%) were Iranian and 89 (62.7%) were Afghani. From 142 patients, 81 (57%) were smear positive and 61 (43%) were smear negative. The mean age (P = 0.51), sex distribution (χ 2 = 1.68; P = 0.2) and the nationality distribution (χ 2 = 0.38; P = 0.38) were not different between smear positive and smear negative patients. There was not any significant difference between the region (χ 2 = 0.94; P = 0.8) and the type (χ 2 = 12.88; P = 0.12) of the lung involvement, too. Conclusion: Based on the results of this study, there was no difference between smear positive and smear negative patients in terms of chest radiography findings. [ABSTRACT FROM AUTHOR]