J Manipulative Physiol Ther. 1988 Aug; 11(4): 273-80.

Biomechanical analysis by chiropractic radiography: Part I. A simple method for determining X-ray projectional distortion.

Zengel F, Davis BP.

Biology Department, St. Louis Community College, Meramec, Missouri.

Projectional distortion is known to produce artifactual disrelationships between the images of osseous segments on X-ray film. Apparatus and methods were developed to measure the effect of projectional distortion on a human third lumbar vertebra. The procedures for mathematical analysis of such distortion are outlined, and the results of studies to determine the accuracy of the procedure are presented.