Low dose chest CT protocol (50 mAs) as a routine protocol for comprehensive assessment of intrathoracic abnormality

Abstract

PurposeTo determine the diagnostic capability of low-dose CT (50mAs) in comparison to standard-dose CT (150mAs). Materials and methodsFifty-nine consecutive patients underwent two non-contrast chest CT scans with different current-time products (50 and 150mAs at 120kVp) on a 64-detector row CT scanner. Three board certified chest radiologists independently reviewed 118 series of 2mm-thick images (2 series for each of 59 patients) in a random order. The readers assessed abnormal findings including emphysema, ground-glass opacity, reticular opacity, micronodules, bronchiectasis, honeycomb, nodules (>5mm), aortic aneurysm, coronary artery calcification, pericardial and pleural effusion, pleural thickening, mediastinal tumor and lymph node enlargement. Five-point scale from 1 (definitely absent) to 5 (definitely present) was used to record the results. The rates of score agreement between two images were calculated. Deviation of one observer's score from other two observers was compared between low dose CT and standard dose CT. ResultsMean agreement rate of the lung parenchymal findings between low dose CT and standard dose CT images was 0.836 (range, 0.746–0.926). Mean agreement rates for mediastinal and pleural findings were 0.920 (range, 0.735–1.000). There was no statistically significant difference in the deviation of the observers' scores between low-dose CT and standard-dose CT. ConclusionLow dose CT protocol at 50mAs can produce the screening results consistent with standard dose CT protocol (150mAs), supporting routine use of low dose chest CT protocol.