Template based scatter correction in clinical brain perfusion SPECT

A practical method for scatter compensation in SPECT imaging is the triple energy window technique (TEW) which estimates the fraction of scattered photons in the projection data pixel by pixel. This technique requires an acquisition of counts in three windows of the energy spectrum for each projection bin, which is not possible on every gamma camera. The aim of this study is to set up a scatter template for brain perfusion SPECT imaging by means of the scatter data acquired with the triple energy window technique. This scatter template can be used for scatter correction as follows: the scatter template is realigned with the acquired, by scatter degraded and reconstructed image by means of the corresponding emssion template, which also includes scatter counts. The ratios between the voxelvalues of this emission template and the acquired and reconstructed image are used to locally adjust the scatter template. Finally the acquired and reconstructed image is corrected for scatter by substracting the thus obtained scatter estimates. We compared the template based approach with the TEW scatter correction technique for data acquired with same gamma camera system and found a similar performance for both correction methods.