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KMID : 1038720130240030162
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Progress in Medical Physics
2013 Volume.24 No. 3 p.162 ~ p.170
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A Low-Dose High-Resolution SPECT System with CdTe for Small-Animal Imaging Applications: A GATE Simulation Study
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Park Su-Jin
Yu A-Ram
Kim Ye-Seul
Lee Young-Jin
Kim Hee-Joung
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Abstract
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Dedicated single-photon emission computed tomography (SPECT) systems based on pixelated semiconductors
are being developed for studying small animal models of human disease. To clarify the possibility of using a
SPECT system with CdTe for a high resolution low-dose small animal imaging, we compared the quality of
reconstructed images from pixelated CdTe detector to those from a small SPECT system with NaI(Tl). The CdTe
detector was 44.8×44.8 mm and the pixels were 0.35×0.35×5 mm. The intrinsic resolution of the detector was
0.35 mm, which is equal to the pixel size. GATE simulations were performed to assess the image quality of
both SPECT systems. The spatial resolutions and sensitivities for both systems were evaluated using a 10 MBq
99mTc point source. The quantitative comparison with different injected dose was performed using a voxelized
MOBY phantom, and the absorbed doses for each organ were evaluated. The spatial resolution of the SPECT
with NaI(Tl) was about 1.54 mm FWHM, while that of the SPECT with a CdTe detector was about 1.32 mm
FWHM at 30 mm. The sensitivity of NaI(Tl) based SPECT was 83 cps/MBq, while that of the CdTe detector based
SPECT was 116 cps/MBq at 30 mm. The image statistics were evaluated by calculating the CNR of the image
from both systems. When the injected activity for the striatum in the mouse brain was 160 Bq/voxel, the CNR
of CdTe based SPECT was 2.30 while that of NaI(Tl) based SPECT was 1.85. The CNR of SPECT with CdTe
was overall higher than that of the NaI(Tl) based SPECT. In addition, the absorbed dose was higher from SPECT
with CdTe than those from NaI(Tl) based SPECT to acquire the same quantitative values. Our simulation results
indicated that the SPECT with CdTe detector showed overall high performance compared to the SPECT with
NaI(Tl). Even though the validation study is needed, the SPECT system with CdTe detector appeared to be feasible
for high resolution low-dose small animal imaging.
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KEYWORD
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SPECT (Single photon emission computed tomography), CdTe, High-Resolution, Low-Dose, Small-Animal imaging
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