A technique for using CT images in attenuation correction and quantification in SPECT

TLDR

The practicalities of applying the technique in patient studies are discussed. The study describes a technique that uses CT images for attenuation correction and quantification in SPECT. CT slices are aligned with SPECT slices, Hounsfield units are converted to linear attenuation coefficients for the SPECT radionuclide, and the resulting attenuation map is used to correct the SPECT reconstruction. Evaluation in non‑anatomical and anatomical phantoms shows a mean activity quantification accuracy of 2.6 % (range 0.3–4.0 %) and demonstrates that scatter correction before attenuation correction improves accuracy.

Abstract

A technique is described for using computed tomography (CT) images for attenuation correction and quantification in SPECT. The CT images are aligned with the corresponding SPECT slices and the Hounsfield units are converted to linear attenuation coefficient values for the SPECT radionuclide. The attenuation coefficient map thus produced is used to provide the attenuation correction required in the SPECT reconstruction. The technique has been evaluated in both a non-anatomical and an anatomical phantom giving a mean accuracy in quantifying activity of various features in the phantoms of 2.6% (range 0.3%-4.0%). The value of performing scatter correction prior to attenuation correction in obtaining accurate quantification is demonstrated. The practicalities of applying the technique in patient studies are discussed.