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Pinhole collimation for ultra-high-resolution, small-field-of-view SPECT.
- Source :
-
Physics in medicine and biology [Phys Med Biol] 1994 Mar; Vol. 39 (3), pp. 425-37. - Publication Year :
- 1994
-
Abstract
- The objective of this investigation was to evaluate small-field-of-view, ultra-high-resolution pinhole collimation for a rotating-camera SPECT system that could be used to image small laboratory animals. Pinhole collimation offers distinct advantages over conventional parallel-hole collimation when used to image small objects. Since geometric sensitivity increases markedly for points close to the pinhole, small-diameter and high-magnification pinhole geometries may be useful for selected imaging tasks when used with large-field-of-view scintillation cameras. The use of large magnifications can minimize the loss of system resolution caused by the intrinsic resolution of the scintillation camera. A pinhole collimator has been designed and built that can be mounted on one of the scintillation cameras of a triple-head SPECT system. Three pinhole inserts with approximate aperture diameters of 0.6, 1.2 and 2.0 mm have been built and can be mounted individually on the collimator housing. When a ramp filter is used with a three-dimensional (3D) filtered backprojection (FBP) algorithm, the three apertures have in-plane SPECT spatial resolutions (FWHM) at 4 cm of 1.5, 1.9 and 2.8 mm, respectively. In-air point source sensitivities at 4 cm from the apertures are 0.9, 2.6 and 5.7 counts s(-1) microCi(-1) (24, 70 and 154 counts s(-1) MBq(-1)) for the 0.6, 1.2 and 2.0 mm apertures, respectively. In vitro image quality was evaluated with a micro-cold-rod phantom and a micro-Defrise phantom using both the 3D FBP algorithm and a 3D maximum likelihood-expectation maximization (ML-EM) algorithm. In vivo image quality was evaluated using two (315 and 325 g) rats. Ultra-high-resolution pinhole SPECT is an inexpensive and simple approach for imaging small animals that can be used with existing rotating-camera SPECT system.
- Subjects :
- Algorithms
Animals
Bone and Bones diagnostic imaging
Colloids
Female
Gamma Cameras
Humans
Image Processing, Computer-Assisted
Likelihood Functions
Liver diagnostic imaging
Phantoms, Imaging
Radioisotopes
Radiopharmaceuticals
Rats
Rats, Sprague-Dawley
Sensitivity and Specificity
Sodium Pertechnetate Tc 99m
Sulfur
Tomography, Emission-Computed, Single-Photon instrumentation
Tomography, Emission-Computed, Single-Photon methods
Subjects
Details
- Language :
- English
- ISSN :
- 0031-9155
- Volume :
- 39
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Physics in medicine and biology
- Publication Type :
- Academic Journal
- Accession number :
- 15551591
- Full Text :
- https://doi.org/10.1088/0031-9155/39/3/010