Results 161 to 170 of about 50,958 (240)
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Analytic calculation of multi-pinhole collimator sensitivity with tilted pinholes
2008 IEEE Nuclear Science Symposium Conference Record, 2008We purpose a modified method for predicting the sensitivity performance by considering the tilted and translated pinhole apertures in a ring-type multi-pinhole collimation design. In addition to the tilted pinholes, we also applied a simple correction scheme for accounting various effects which cause the performance bias between the analytical and MC ...
null Ho-Hui Hsieh +3 more
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Resolution of pinhole collimators used with gamma cameras
Medical Physics, 1980The line spread function (LSF) of an imaging system incorporating a pinhole of 0.275 cm radius and a scintillation camera has been measured and its full width at half maximum (FWHM) compared to the values predicted by an expression based on the resolution index of Anger.
P, Goulet, M L, Joy
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Analytic determination of pinhole collimator sensitivity with penetration
IEEE Transactions on Medical Imaging, 2001Pinhole collimators are widely used to image small organs and animals. The sensitivity of knife-edge pinhole collimators has been previously estimated using an "effective diameter" formulation and experimentally described using a sin(x) theta fit, where theta is the angle between the line segment from the center of the aperture to the photon source and
S D, Metzler +3 more
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Three-pinhole collimator to improve axial spatial resolution and sensitivity in pinhole SPECT
European Journal of Nuclear Medicine and Molecular Imaging, 2007The aim of this study was to improve the uniformity of the axial spatial resolution and sensitivity in pinhole single-photon emission computed tomography (SPECT) and to extend the axial field of view, by using a dedicated three-pinhole collimator.A rectangular tungsten plate with three pinhole apertures of 1.5 mm diameter was designed to image a ...
Vanhove, Christian +3 more
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Transformation acoustics: virtual pinholes and collimators
The Journal of the Acoustical Society of America, 2012In this invited talk, our preliminary study is presented on a virtual hole and a broadband acoustic collimator, by combination of the concept of complimentary media with transformational acoustics. Such effect is exemplified by a segmental defect in the original cloak, which appears as if a dipole scatterer was under the acoustic imager.
Jun Xu, Yun Jing, Nicholas X. Fang
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Comparison of pinhole collimator materials based on sensitivity equivalence
Physics in Medicine and Biology, 2011Pinhole SPECT often provides an excellent resolution sensitivity trade-off for radionuclide imaging compared to SPECT with parallel holes, particularly when imaging small experimental animals like rodents. High absorption pinhole materials are often chosen because of their low edge penetration and therefore good system resolution.
Victor, Bom +2 more
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Pinhole collimator design for nuclear survey system
Annals of Nuclear Energy, 2002A conventional knife-edge collimator, which is widely used in gamma camera for medical diagnosis, is not suitable for nuclear imaging system because many scattering radiations near the pinhole aperture happen and blur image. A new pinhole collimator, which shapes a channeled aperture for reducing image degradation induced by the scattering radiations ...
Lee, W, Cho, G Cho, Gyuseong
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The Scintillation Camera with Pinhole Collimator in Thyroid Imaging
Radiology, 1971Thyroid images of 100 patients were obtained using both a gamma camera with a pinhole collimator and a rectilinear scanner with an 8-inch crystal. The pinhole images were better in 64 patients, the scans better in 11, and they were equal in 25. The average quality of the pinhole images was higher than that of the scans.
P J, Hurley +4 more
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Resolution-effective diameters for asymmetric-knife-edge pinhole collimators
IEEE Transactions on Medical Imaging, 2005The effects of penetration are included in the formulas for the prediction of the resolution of pinhole collimators through the use of effective diameters. Expressions of the resolution-effective diameter for pinholes with a double-knife-edge (DKE) profile are available in the literature.
Roberto, Accorsi, Scott D, Metzler
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Comparison of two small animal PET scanners: Pinhole collimation vs. electronic collimation
2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC), 2012PET imaging of rodents is increasingly used in preclinical research, but its utility is limited by the spatial resolution and statistical quality of the images. In a new approach, a specially designed pinhole collimator enables high-resolution, simultaneous imaging of PET and SPECT tracers.
Matthew D. Walker +8 more
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