A novel high-energy I-131 scatter correction technique which includes correction for gamma camera scatter

The performance of conventional Triple Energy Window (TEW) scatter correction for high-energy ¹³¹I studies can be improved, in some cases, by altering the TEW weighting factors, but this fails to produce the all-round accuracy required. A new energy-window based scatter correction (CSC-Camera Scatter Correction) was used in addition to the TEW method. An energy window was centred at 76 keV and the lead X-rays used to provide angular information about the incident photons. This allowed correction for photons scattered in the collimator. In order to assess CSC and to provide a general ¹³¹I imaging analysis tool, a new Monte Carlo package was developed. Its design reflects the increased importance, with respect to low-energy gamma emitters, of camera head interactions for ¹³¹I imaging. Applying CSC to experimental point, rod and cylinder phantoms resulted in recovery of the narrow beam attenuation coefficient for ¹³¹I of 0.11 cm^-1, compared to mean TEW value of 0.09 cm^-1. CSC offers improved accuracy for ¹³¹I scatter correction, but at the expense of a loss in precision, due to the extra window subtraction