MONITORING AND CORRECTION OF MULTIPLE SCATTER DURING CLINICAL COMPTONSCATTER DENSITOMETRY MEASUREMENTS

A system for monitoring multiple scatter during a clinical Compton sca tter densitometry measurement of bone density is described. Multiple s catter from the measurement site was measured using a supplementary co llimated detector positioned so that only multiply scattered photons C ould enter the detector. The data from the detector were used to form a multiple-scatter correction factor (mcf) to correct for the bias att ributed to multiple scatter. The results of experimental and computer simulations are presented which demonstrate the relationship between t he multiple-scatter reading and calculated mcf values. The influence o f bone size on the values of mcf in large measurement sites, such as t he femoral neck, was shown to he negligible. A simulation was used to produce a visualization of the multiple scatter in order to ascertain the optimum position of the supplementary detector. This technique was shown to be a rapid and accurate method of measuring the multiple-sca tter bias and suitable for use during clinical CSD measurements.