Effect of x-ray tube potential on image quality and patient dose for lumbar spine computed radiography examinations

A study was conducted to investigate the effect of increasing x-ray tube voltage on patient dose and image quality during computed radiography (CR) examination of the lumbar spine. Images of a pelvis - lumbar spine phantom were obtained at three different tube voltages using two CR systems. The images were evaluated by image scores (IS) using the image quality criteria proposed by the Commission of the European Communities (CEC), by measuring the signal-to-noise ratio and the contrast-to-noise ratio. The entrance surface dose (ESD) to the phantom was also measured using ionisation chambers and the resulting gonad dose (G) and effective dose (E) were calculated. The CEC recommended tube voltages can be exceeded with CR systems for lumbar spine radiography. The ESD, G and E decreased by 25% - 50% with both CR systems when tube voltage was increased. Although the decrease in IS was statistically significant (P<0.05) the images obtained with the 3 tube voltages were diagnostically acceptable. The balance between image quality and patient dose can be optimised by using higher x-ray tube voltages for lumbar spine CR examinations. Copyright © 2005 ACPSEM/EA.