Investigation of the relationship between linear attenuation coefficients and CT Hounsfield units using radionuclides for SPECT

This study has investigated the relationship between linear attenuation coefficients (μ) and Hounsfield units (HUs) for six materials covering the range of values found clinically. Narrow-beam μ values were measured by performing radionuclide transmission scans using 99mTc, 123I, 131I, 201Tl and 111In. The μ values were compared to published data. The relationships between μ and HU were determined. These relationships can be used to convert computed tomography (CT) images to μ-maps for single photon emission computed tomography (SPECT) attenuation correction.