CORRECTION OF ELONGATION ERROR BY PRODUCING EQUILIBRIUM ERROR

Abstract

The equilibrium error was produced by raising adjustable orthopaedics ruler to the same plane of a PVC phantom of leg to be possible to use teleroentgenographic method. The results showed that by this method the scale error occurred in the same amount as the elongation error. The measured limb length on radiograph was closely approximate to the actual length. It indicated that elongation error was eliminated by producing equilibrium error. The effect of centering the X-ray tube at various levels for measuring the anterior surface of the bone to the film (ASBF) was identified. The center ray of X-ray beam at the upper, middle and lower border of a cross-surface phantom were performed by lateral cross table radiography. The results showed that there is no statistically significant difference between the ranks” of the values of the three measured ASBF (P>0.05). It indicated that X-ray beam centered at skin from ventral to dorsal of leg did not affect the measured ASBF. It is convenience for routine work in JAN. - APR. 1999. Volume V Number I clinical practice.
N.B. : ranks’ is the special term in statistics and is used in cases when the values analyzed are not enough to find the mean. ASBF = Anterior Surface of the Bone to the Film.