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A theoretical approach has been developed that allows the geometric transfer function component for conventional scintillation camera collimators to be predicted in closed form. If transfer function analysis is to be useful in describing imaging system performance, the image of a point source must not depend on source position in a plane parallel to the detection plane. This shift invariance can be achieved by analysis of system response in terms of an effective point spread function, defined as the normalised image of a point source that would be obtained if the camera collimator were uniformly translated (but not rotated) during image formation. The geometric component of the corresponding effective transfer function is shown to be expressed simply by the absolute square of the two-dimensional Fourier transform of a collimator hole aperture, with the spatial frequency plane scaled by a factor which depends on collimator length, source-to-collimator distance, and collimator-to-detection plane distance. Closed form algebraic expressions of the geometric transfer function have been obtained for all four common hold shapes (circular, hexagonal, square and triangular). Monte Carlo simulations and experimental measurements have shown these theoretical expressions to be highly accurate.

A CCD-based bistatic lidar (CLidar) system has been developed and constructed to measure scattering in the atmospheric boundary layer. The system uses a CCD camera, wide-angle optics, and a laser. Imaging a vertical laser beam from the side allows high-altitude resolution in the boundary layer all the way to the ground. The dynamic range needed for the molecular signal is several orders of magnitude in the standard monostatic method, but only approximately 1 order of magnitude with the CLidar method. Other advantages of the Clidar method include low cost and simplicity. Observations at Mauna Loa Observatory, Hawaii, show excellent agreement with the modeled molecular-scattering signal. The scattering depends on angle (altitude) and the polarization plane of the laser.

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An expression for the expected image of a spherical tumour in a uniform background was derived in terms of background thickness and concentration of radioactivity, the tumour size, depth and uptake ratio, the gamma-ray energy and the detector response function. Three models of human observer performance for tumour detection were developed from different signal-to-noise ratio measures based on the statistical theory of detection. The optimum detector spatial resolution predicted by each model was then compared to that obtained from an observer performance study in which the subjects viewed computer-simulated scintigrams. The predictions from two of these models seem to be consistent with the results of the observer performance study. Model II involves a comparison of the counts integrated over the tumour region with the counts integrated over a background region of the same area. Model III compares the count density estimates of signal-plus-background and background obtained from application of non-uniform weighting functions to the image data.

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A complete. Analysis of the response of a collimated s c i n t i l l a t i o n det e c t o r t o. a n i r i v i v o distribution of radioactivitymust include the responses' t o. . & t E s c a t t e r e d : y-rays and the continuous spectrum of photons. ' 3. ' An X-ray component,. c h a m c t e r k t i c ;of .the' collimator material, .due t o photoelectric .interactions ,of .the' incoming photons with' the' ' collimator w a l l s ; The .detector used. to. obtain the' ? 3~g spectrum in *. ., .