Applications of Multi-Pinhole Gamma Camera Collimation to Tomography and Image Enhancement

148 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.Recently, multi-pinhole gamma camera collimation has been introduced in the field of emission tomography. This collimation process simultaneously produces several images covering a limited angular range, which may then be recombined to obtain tomographic slices of the object imaged. This study has investigated a possible method for improving the images obtained by this technique by combining two multi-pinhole views taken 90(DEGREES) apart. In this way, the problems arising from the limited angle of view should be reduced. During the course of this work, multi-pinhole collimation was also applied to in vivo imaging of the disintegration of tablets. Parameters normally difficult to measure, such as the timing and method of disintegration, can readily be observed with this technique. Collimators were designed and built both for tomography and imaging tablet disintegration, and computer programs were written to reconstruct the images by simple backprojection and by filtered backprojection.Two-view multi-pinhole tomography provided only limited image enhancement over a single view. This enhancement primarily occurred at the farthest depths and so would be useful in imaging objects deep within the body. Enhancement was most apparent when two views at opposite 45(DEGREES) angles to the desired plane were combined.The use of multi-pinhole collimators to image the disintegration of tablets in vivo was clearly demonstrated. Phantom tests done in vitro were capable of imaging defects as small as 5 mm('2), while images made with real tablets bith in vitro and in vivo readily showed the onset and progress of the tablet disintegration. Further experiments are planned using this technique to measure gastric emptying times and disintegration times of various tablet formulations.Limitations of the multi-pinhole technique, previously observed by others, were also observed in this study. These limitations included problems such as limited ranges of viewing and artifacts introduced due to incomplete sampling.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD