Evaluation of a low-dose/slow-rotating SPECT-CT system.
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.
Hamann
M
M
Institute of Nuclear Medicine-UCL, London, UK.
Aldridge
M
M
Dickson
J
J
Endozo
R
R
Lozhkin
K
K
Hutton
B F
BF
D005528:Foot / Q000000981:diagnostic imaging; D011829:Radiation Dosage; D012399:Rotation; D012680:Sensitivity and Specificity; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*