Nucl Med Mol Imaging.  2008 Feb;42(1):62-69.

Development of Geometric Calibration Method for Triple Head Pinhole SPECT System

Affiliations
  • 1Department of Nuclear Medicine, College of Medicine, Seoul National University, Seoul, Korea. jaes@snu.ac.kr
  • 2Interdisciplinary Program in Radiation Applied Life Science Major, College of Medicine, Seoul National University, Seoul, Korea.
  • 3Institute of Radiation Medicine, Medical Research Center, Seoul National University, Seoul, Korea.

Abstract

PURPOSE: Micro-pinhole SPECT system with conventional multiple-head gamma cameras has the advantage of high magnification factor for imaging of rodents. However, several geometric factors should be calibrated to obtain the SPECT image with good image quality. We developed a simplified geometric calibration method for rotating triple-head pinhole SPECT system and assessed the effects of the calibration using several phantom and rodent imaging studies. MATERIAL AND METHODS: Trionix Triad XLT9 triple-head SPECT scanner with 1.0 mm pinhole apertures were used for the experiments. Approximately centered point source was scanned to track the angle-dependent positioning errors. The centroid of point source was determined by the center of mass calculation. Axially departed two point sources were scanned to calibrate radius of rotation from pinhole to center of rotation. To verify the improvements by the geometric calibration, we compared the spatial resolution of the reconstructed image of Tc-99m point source with and without the calibration. SPECT image of micro performance phantom with hot rod inserts was acquired and several animal imaging studies were performed.
RESULTS
Exact sphere shape of the point source was obtained by applying the calibration and axial resolution was improved. Lesion detectibility and image quality was also much improved by the calibration in the phantom and animal studies.
CONCLUSION
Serious degradation of micro-pinhole SPECT images due to the geometric errors could be corrected using a simplified calibration method using only one or two point sources.

Keyword

geometric calibration; pinhole SPECT; center of rotation error

MeSH Terms

Animals
Calibration
Gamma Cameras
Head
Imidazoles
Nitro Compounds
Radius
Rodentia
Tomography, Emission-Computed, Single-Photon
Track and Field
Imidazoles
Nitro Compounds
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