1993 Fiscal Year Final Research Report Summary

Development of Ultra-high Resolution Single Photon Emission Computed Tomography(SPECT) Using Pinhole-Collimator

Research Project

Project/Area Number	04680235
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Nuclear engineering
Research Institution	Kyoto College of Medical Technology
Principal Investigator	MUKAI Takao Kyoto College of Medical Technology, Dept.of Radiological Technology. Professor, 診療放射線技術学科, 教授 (40093322)
Project Period (FY)	1992 – 1993
Keywords	Pinhole collimator / Single Photon Emission CT (SPECT) / Gamma Camera / Radiopharmaceutical / Blood Flow / Neuro Transmitter / Neuro Receptor
Research Abstract	Radionuclide imaging of small animals is useful for development of the radiopharmaceuticals as well as for studying various animal disease models. Although todays SPECT systems provide an excellent resolution(8-10mm), these are not sufficient for small animal studies including rats, mice and gerbils. In order to achieve less than 2mm spatial resolution, we have attempted to construct an ultra-high resolution SPECT system using pinhole collimators. The pinhole collimator were made of cone shaped lead shield and tungsten pinhole with effective aperture size of 1.0 and 2.0mm. Four pinhole collimators are attached to 4-head SPECT scanner with fixed distance from pinhole to camera (130mm) and from pinhole to rotating axis (50mm). The field of view was 50mm in diameter and 12.3mm in axial direction with minimum slice thickness of 0.51mm. Filtered back projection algorithm was used to reconstruct SPECT images after fan-parallel projection data conversion. The system provided spatial resolution of 1.65mm (FWHM) and sensitivity of 116 cps/kBq/ml with 1.0mm pinhole collimator. In animal studies by rats with Tc-99m blood flow tracers, brain structures and myocardial wall were resolved clearly. Dynamic SPECT imaging of benzodiazepine receptor in rat brain showed the meaning time activity curves at every region of the brain. This ultra-high resolution pinhole SPECT system will contribute to development of new radiopharmaceuticals and disease models in living animals.