Using simultaneous transmission and scatter SPECT imaging from external sources for the determination of the thoracic μ-map

The authors describe a new technique that uses simultaneous transmission and scatter SPECT imaging for determination of segmented attenuation μ-maps. These μ-maps could provide the basis for attenuation correction and quantification of radiopharmaceutical uptake in cardiac SPECT. For transmission imaging, a line source and a fan-beam collimator on one head of a triple-head SPECT system are used. For scatter imaging, two external ring sources and parallel collimators on one or two of the other heads are used. The fan-beam transmission data are truncated, while the parallel-beam data are not. The proposed technique uses both sets of tomographic data to complement each other and to obtain a composite image. A μ-map with three segmented regions of distinct μ-values could be derived from the composite image. This final μ-map can then be used as the basis for attenuation correction