| Project/Area Number |
61460225
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
医学一般
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| Research Institution | The University of Tokyo |
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Principal Investigator |
FUJIMURFA Sadao Univ. of Tokyo, Associate Prof., 工学部, 助教授 (30010961)
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| Co-Investigator(Kenkyū-buntansha) |
YAMADA Norihide Univ. of Tokyo, Assistant Researcher, 工学部, 助手 (30182546)
TANAKA Hiroshi Univ. of Tokyo, Lecturer, 医学部, 講師 (60155158)
KATSULAI Hiroshi Chiba Inst. of Tech., Lecturer, 電子計算センター, 講師 (00009705)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 1987: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1986: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Computed tomography / Coded aperture / Emission CT / Autocorrelation function / m-sequence / M-array / 断層像 / 符号化開口 / 断層像の再生 |
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| Research Abstract |
This study aims at the development of a new method for coded apzrture emission CT (Computed Tomography), more specifically the development of a simple algorithm for obtaining tomographs at various depth by solving an inverse problem. The solution of the problem is given by matched filtering using a two-dimensional pseudo-random signal, M-array. The autocorrelation function of the M-array is approximately the delta function, which makes it very easy to solve the problem.
The CT system is composed of an M-array coded aperture, a two-dimensional array sensor betecting the projection, and a digital computer for reconstruction of 3-dimensional distribution of emeission sources. The 3-dimensional position of a source is determined by the cross-correlation function between the projection a d a magnified M-array, whose magnification is specified by the depth at which the image is reconstructed.
We examined the algorthm by using numerical simulation and also by actual experiments using gamma camera and a phantom containing RI. The result of the examination was almost satisfactory. It showed that the resolution for depth was not very good, and in some limited cased it yielded ghosts in the reconstructed image. We clarified the reason for the ghosts and developed a method to eliminate them by image processing. We tried to improve the resolution for depth by using two projects obtained while the aperture was displaced a little bit in the direction of depth between the two projections. This gave a sharp point spread function which means that the resolution was improved. This yielded also a sharpening effect on the image.
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