The effect of scattered radiation in dual-energy analysis

Dual-energy techniques can be used to provide additional information during x-ray examinations. A recent development has been in the application of dual-energy analysis to fluoroscopic procedures. In this paper the effects of scattered radiation upon the results obtained with a small area, dual-energy probe used during fluoroscopy has been evaluated. The method employed has been the development and application of a Monte Carlo photon transport computer program. Experimental confirmation of the model has been performed and the model extended to study the effects of scattered radiation upon the chemical sensitivity of the dual-energy probe. These effects have been studied using a simplified phantom geometry to represent a homogeneous patient. The results indicate that for tissue analysis where the effective atomic number (Z) is less than 13 the effects of scattered radiation lead to errors in estimates of Z of +/- 0.25 when the acceptance angle of the detected radiation is below +/- 20 degrees.