Impact on image quality when a variety of X-ray source detector distances are considered for the arthritic cervical spine

The unavoidable distance between the cervical spine and the image receptor presents measurable levels of geometric unsharpness, which hinders arthritic scoring. The current work explores the impact on the visualisation of important arthritic indicators by increasing the distance between the X-ray source and image detector (SID) from the commonly employed 150cm. Lateral cervical spine images were acquired of an osteoarthritic human cadaver using a DR imaging system. All exposures were taken at 65kVp using automatic exposure control and various SID distances from 150 to 210cm. Four experienced clinicians assessed the images by means of visual grading analysis, using objective criteria based on normal anatomic features and arthritic indicators. A statistically significant improvement in image quality was observed with images-acquired at 210cm compared with those acquired at 150cm and 180cm (p<0.05), with values of 56.0 (SE=1.105), 50.85 (SE=1.415) and 65.35 (SE=0.737) respectively. All images with a SID of 210cm scored higher for visually sharp reproduction of the spinous processes, facet joints, intervertebral disc spaces and trabecular bone pattern compared with both 180cm and 150cm. Results indicate that total image quality and visualisation of specific anatomical features is improved in cervical spine radiographs when traditionally employed SID distances are increased.