Evaluation of a low-dose/slow-rotating SPECT-CT system

Phys Med Biol. 2008 May 21;53(10):2495-508. doi: 10.1088/0031-9155/53/10/003. Epub 2008 Apr 18.


The 4-slice CT that forms part of the GE Infinia Hawkeye-4 SPECT-CT scanner (Hawkeye) is evaluated against the diagnostic 16-slice CT that is incorporated in the GE Discovery ST PET-CT system (DST). The x-ray tube of the slow-rotating Hawkeye system (23 s/rotation) operates at approximately a third of the dose of diagnostic systems as used for conventional diagnostic imaging. Image reconstruction is optimized for low noise. High-contrast spatial resolution significantly falls behind diagnostic figures: the average of MTF(50) and MTF(10) (resolution where the MTF has fallen to 50% and 10%) is 2.8 +/- 0.1 cm(-1) for Hawkeye and 5.3 +/- 0.1 cm(-1) for the DST (standard reconstruction filters). Resolution in the direction of the couch movement (z coordinate) is governed by the fixed Hawkeye slice width of 5 mm. Reconstruction accuracy is found to be increased by reducing the default z increment from 4.4 mm to 2.2 mm. Low-contrast object detectability is superior compared with diagnostic systems operating in the Hawkeye dose range. In the diagnostic dose regime, however, small low-contrast details remain visible in DST that are not detectable with Hawkeye. Although not of diagnostic quality, the low-dose Hawkeye provides appropriate data for SPECT attenuation correction and anatomical localization capability.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Foot / diagnostic imaging
  • Radiation Dosage*
  • Rotation
  • Sensitivity and Specificity
  • Time Factors
  • Tomography, Emission-Computed, Single-Photon / methods*
  • Tomography, X-Ray Computed / methods*