| Project/Area Number |
01460244
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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 | University of Tokyo |
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Principal Investigator |
FUJIMURA Sadao Univ of Tokyo, Fac of Eng, Prof, 工学部, 教授 (30010961)
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| Co-Investigator(Kenkyū-buntansha) |
KATSULAI Hiroshi Chiba Inst of Tech, Assoc Prof, 助教授 (00009705)
ITO Tadashi Univ of Tokyo, Fac of Eng, Research Assist, 工学部, 助手 (20223159)
ISHIKAWA Masatoshi Univ of Tokyo, Fac of Eng, Assoc Prof, 工学部, 助教授 (40212857)
山田 範秀 東京大学, 工学部, 助手 (30182546)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1990: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1989: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Computed Tomography / Coded Aperture / Projection / M-array / Matched Filter / 3-D distribution / Radio Isotope (RI) / Inverse Problem / 3次元分布 / 符号化開口 / 放射型CT |
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| Research Abstract |
Three dimensional distribution of radiation emitters was measured by a simple method using a random-coded aperture and a 2-dimensional (area) sensor. The aperture was coded by a pseudo-random pattern (M-array composed of maximum-length sequence), whose auto-correlation function is approximately a Dirac's delta function. The M-array we used was composed of 8-tuple m-sequence (period is 255), and the dimension of the aperture made of a 3 mm thick lead plate was about 200X180 mm2 which includes 4X4 periods of M-arrays. The hole has 2 mm diameter, and the pitch of the holes was 3 mm.
It was confirmed that the spatial resolution obtained by a single projection in the plane parallel to the aperture was about 5 mm, and that in the direction of depth was about 50 mm (at the depth of 300 mm) for an object with 70X70X140 mm3.
We developed a method by using multiple projection and iterative algorithm to improve the resolution especially in depth. We confirmed the validity of the method by employing computer simulation and laboratory experiments. We used two projection in two ways for improvement. At first, we re-constructed an image from two projection images obtained while the aperture was moved in the direction of depth. The second method is to use two projection images obtained by two detector arrays separately located in the same plane. In each case the resolution in depth of the image was much improved. It was aconfirmed that the iterative algorithm was useful for the improvement. The resolution in depth was about 15 mm at the depth of 300 mm for an object with the dimension of 60X60X60 mm3.
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