External nuclear medicine diagnostic imaging of early primary and metastatic lung cancer tumors is difficult due to the poor sensitivity and resolution of existing gamma cameras. Nonimaging counting detectors used for internal tumor detection give ambiguous results because distant background variations are difficult to discriminate from neighboring tumor sites. This suggests that an internal imaging nuclear medicine probe, particularly an esophageal probe, may be advantageously used to detect small tumors because of the ability to discriminate against background variations and the capability to get close to sites neighboring the esophagus. The design, theory of operation, preliminary bench tests, characterization of noise behavior and optimization of such an imaging probe is the central theme of this work. The central concept lies in the representation of the aperture shell by a sequence of binary digits. This, coupled with the mode of operation which is data encoding within an axial slice of space, leads to the fundamental imaging equation in which the coding operation is conveniently described by a circulant matrix operator. The coding/decoding process is a classic coded-aperture problem, and various estimators to achieve decoding are discussed. Some estimators require a priori information about the object (or object class) being imaged; the only unbiased estimator that does not impose this requirement is the simple inverse-matrix operator. The effects of noise on the estimate (or reconstruction) is discussed for general noise models and various codes/decoding operators. The choice of an optimal aperture for detector count times of clinical relevance is examined using a statistical class-separability formalism.

The purpose of this investigation was to study the radiations of the 169/Tm nucleus as it de-excites after the electron capture decay of the 169/Yb. Numerous unreported gammas were present in the sample. The origins of these gamma rays were found.

The purpose of this investigation was to attempt to resolve the energy levels of Cs133 that can be excited by inelastic scattering of 14 Mev neutrons.

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A neutron multiplicity detector system has been developed to study weak pure neutron evaporation channels from heavy-ion reactions. Such a system allows us to study nuclei far away from the line of β-stability - in particular, self-conjugate nuclei where the shell-effects for protons and neutrons are in phase and their combined effects may drive the nucleus towards superdeformation. The system consists of a neutron wall - 4 large volume Ge(Li) γ-ray detectors positioned as close as possible to the target. Neutron-gamma coincidences were recorded and neutron multiplicity events could be extracted from the data. Rejection of gamma-ray events in the neutron detectors was achieved by time-of-flight and pulse shape discrimination methods. A surface barrier detector at 0⁰ allowed a further rejection of charged particle events - especially events which feature neutrons as well.

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Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1973. / Bibliography: leaves [120]-125. / xi, 125 l illus., tables