| Project/Area Number |
15209063
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Pathobiological dentistry/Dental radiology
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| Research Institution | Okayama University |
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Principal Investigator |
KATO Hirokazu Okayama University, Medical School, Faculty of Health Sciences, Professor (60127511)
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| Co-Investigator(Kenkyū-buntansha) |
ASAUMI Jun-ichi Okayama University, Hospital of Medicine and Dentistry, Senior Assistant Professor (60184131)
HONDA Yasutoshi Okayama University, Graduate school of Medicine, Dentistry and Pharmaceutical Sciences, Assistant Professor (40284070)
YANAGI Yoshinobu Okayama University, Hospital of Medicine and Dentistry, Assistant Professor (50284071)
TAKAHASHI Norio Okayama University, Graduate School of Natural Science and Technology, Professor (40108121)
YAMAMOTO Yoshitake Okayama University, Medical School, Faculty of Health Sciences, Professor (50032941)
岸 幹二 岡山大学, 大学院・医歯学総合研究科, 教授 (30033202)
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| Project Period (FY) |
2003 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥39,130,000 (Direct Cost: ¥30,100,000、Indirect Cost: ¥9,030,000)
Fiscal Year 2006: ¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000)
Fiscal Year 2005: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2004: ¥13,130,000 (Direct Cost: ¥10,100,000、Indirect Cost: ¥3,030,000)
Fiscal Year 2003: ¥14,950,000 (Direct Cost: ¥11,500,000、Indirect Cost: ¥3,450,000)
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| Keywords | MRT / Dentistry / Unilateral magnet / NMR / Optimization / 歯科用MRI / unilateral MRI / one-sided型 MRI / 開磁路型磁気回路 / 緩和時間 / ファントム / 画像再構成 |
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| Research Abstract |
To develop a small-sized MRI for dentistry, we developed an MRI phantom and designed a magnetic circuit. We then developed trial units of the magnetic circuit and of a maxillofacial MRI system, collected image data signals, and reconstructed the MR images. Based on this research, we applied for a patent on the unilateral magnetic circuit.
1. Development of phantom: We developed a phantom having human-tissue equivalent T1 and T2 relaxation times, and human-tissue-equivalent (except for fat) conductivity. Any shape of the phantom can be made, as it is in gel form.
2. Design of a magnetic circuit algorithm: A spatially uniform magnetic field is difficult to generate with a magnetic circuit using an open-type magnet because of its structure. To overcome this, we conceived a "scaled evolution strategy method", which enabled us to effectively reduce the number of objective functions.
3. Trial development of magnetic circuit: Based on the above design method, we developed a lateral magnetic circ
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uit.
4. Trial development of a maxillofacial MRI system: We developed a relatively small magnetic circuit into which the patient's head can be positioned. We also constructed an MRI unit, and reconstructed MR images from the obtained data.
5. Development of lateral magnetic circuit: Generally, the magnetic field of a unilateral magnetic circuit decreases with the increase of distance from the surface of the magnetic circuit. In our research, however, we designed a unilateral magnetic circuit having three-dimensionally uniform distribution in a target volume apart from the magnetic circuit surface. By means of combination of 16 magnetic blocks, the directions of the magnetic fields in the target region became parallel to the surface of the magnetic circuit. Using the 3-dimensional finite element method, a magnetic circuit 400 mm x 400 mm x 200 mm in size had a magnetic flux density of 64.5mT in a region of interest (ROI) 55 mm from the surface of the magnetic circuit. The uniformity was 28 ppm when the ROI size was 10 mm x 10 mm x 1 mm, and 613 ppm when 20 mm x 20 mm x 10 mm in size. Less
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