The effects of kilovoltage on diagnostic accuracy in chest radiography

Chest examinations, consisting of three posteroanterior chest radiographs obtained at 75,120, and 140 kVp, were performed on patients with clinically suspected pulmonary disease. The 66 sets of radiographs included 23 lung cancers, 13 other clinically relevant abnormalities, and 27 normals. All findings were verified by clinical or radiologic follow-up except for three cases that could not be verified and were excluded from later analysis. Six radiologists viewed the series of 198 radiographs one at a time in a randomized sequence. They scored each radiograph and each suspected abnormality with a confidence rating from 1 (normal) to 4 (definitely abnormal). Based on these scores receiver operating characteristic (ROC) curves were plotted for each set of kVp settings. The results indicated that higher kVp values improved diagnostic accuracy. Analysis of the ROC curves showed statistically significant differences between 140 kVp and both 120 kVp and 75 kVp, but not between the two lower kVp values.