の設計に関する研究
著者
安藤 竜弥
雑誌名
東北大学電通談話会記録
巻
89
号
2
ページ
2-5
発行年
2021-03-04
URL
http://hdl.handle.net/10097/00130871
༤ኈᏛㄽᩥせ⣙㸦௧2 ᖺ 9 ᭶㸧
㧗㛤ᨺᆺ
MRI ࠾ࡅࡿ㧗ᆒ୍㧗Ᏻᐃ☢ሙ㉸㟁ᑟ☢▼ࡢタィ㛵ࡍࡿ◊✲
Ᏻ⸨ ❳ᘺ
ᣦᑟᩍဨ㸸ὠ⏣
⌮
A Study on the Design Guideline for High Stable and High Homogeneous
Superconducting Open MRI Magnets
Ryuya ANDO
Supervisor: Makoto TSUDA
In order to reduce the fear of people with claustrophobia, "open" design of MRI superconducting magnet is effective. In this study, three technical problems in designing open MRI magnets are investigated and solved. First, a method enabling magnetic field design of highly open MRI magnets using the combination of a simulated annealing and a singular value decomposition is proposed and trial designs are made using this method. Next, a new method to suppress degradation of MRI image quality due to external magnetic flux is proposed and its function is verified. Finally, the relationship between the coil deformation or displacement and the quench of an open MRI magnet is investigated. The design guidelines for highly open MRI magnets are developed based on these studies.
㻝㻚㻌 䛿䛨䜑䛻㻌
MRI (Magnetic Resonance Imaging) ᳨ᰝ䛿䚸ᙉ☢ ሙ䛸㧗࿘Ἴ☢ሙ䛸䜢⏝䛔䛶Ỉ⣲ཎᏊ䛻☢Ẽඹ㬆䜢 ⏕䛨䛥䛫䚸䛭䛾㝿䛻ᚓ䜙䜜䜛ಙྕ䜢䜒䛸䛻Ỉ⣲ཎᏊ䛾 䝇䝢䞁䛾ศᕸ䜢⏬ീ䛧䛶ேయ䛺䛹䛾᩿ᒙീ䜢ീ䚸 ほᐹ䛩䜛᳨ᰝ䛷䛒䜛䚹MRI⏝㉸㟁ᑟ☢▼䛿䚸䛣䛾䛯 䜑䛾ᙉຊ䛛䛴Ᏻᐃ䛺ᆒ୍☢ሙ䜢⏕ᡂ䛩䜛⨨䛷䛒 䜛䛜䚸ୡ⏺ேཱྀ䛾5䡚7%Ꮡᅾ䛩䜛䛸䛔䜟䜜䜛1)䚸㛢ᡤ 䛻ᜍᛧ䜢ឤ䛨䜛ே䛯䛱䛾䚸MRI᳨ᰝ䛷䛾ᜍᛧ䜢⦆ 䛩䜛䛯䜑䚸䜘䜚㛤ᨺⓗ䛻タィ䛩䜛䛣䛸䛜ᮃ䜎䜜䜛䚹䛧 䛛䛧䚸㧗㛤ᨺ䛷䛒䜛䛣䛸䛿ᚲ↛ⓗ䛻䚸䛯䜛㉳☢ຊ※ 䛷䛒䜛㉸㟁ᑟ䝁䜲䝹䜢ീ✵㛫䛛䜙㐲䛦䛡䛦䜛䜢ᚓ 䛺䛔䛣䛸䜢ព䛧䚸䛭䛾タィ䜢㞴䛧䛟䛩䜛䚹 ᮏ◊✲䛿䚸௨ୗ䛾䜘䛖䛺ᢏ⾡ㄢ㢟䜢タᐃ䛧ゎỴ䛩 䜛䛸䛸䜒䛻䚸㧗㛤ᨺMRI⏝㉸㟁ᑟ☢▼䛾タィᣦ㔪䜢 ᚓ䜛䛣䛸䜢┠ⓗ䛸䛩䜛䚹(1)䛯䜛㉳☢ຊ※䛜ീ✵ 㛫䛛䜙㐲䛔䛸䛔䛖ไ⣙䛾䜒䛸䛷䛾☢Ẽタィ䛿ᐜ᫆䛷 䛺䛟䚸☢▼䛿ᆺ䚸」㞧䛧䛜䛱䛷䛒䜛2)䚹䛭䛣䛷㉸ 㟁ᑟ䝁䜲䝹䛻ຍ䛘䚸☢ᛶయ䜢ຠᯝⓗ䛻ే⏝䛩䜛䛣䛸 䛷༢⣧䛺య⣔䛷ྜ⌮ⓗ䛺☢Ẽタィ䜢ᚓ䜛ᡭἲ䛸☢ Ẽタィ䛾ᣦ㔪䜢ᵓ⠏䛩䜛䚹(2)እ㒊䛛䜙☢▼䛻ධ 䛩䜛☢᮰䛿☢ሙ䛾Ᏻᐃᛶ䜢䛧MRI䛾⏬㉁䜢ຎ䛥 䛫䜛3)䛯䜑䚸䛣䜜䜢ᢚไ䛩䜛ᚲせ䛜䛒䜛4)䚹㧗㛤ᨺ☢ ▼䛻䛚䛔䛶䜒ຠᯝⓗ䛻እ㒊☢᮰䛾ධ䜢ᢚไ䛩䜛 ᵓᡂ䜢ᵓ⠏䛧䛭䛾ᇶᮏ≉ᛶ䜢ヨసホ౯䛩䜛䛣䛸䛷䚸 Ᏻᐃ䛺☢ሙ䜢ᚓ䜛䛯䜑䛾ᣦ㔪䜢ᵓ⠏䛩䜛䚹(3)☢▼ 䛚䜘䜃䝁䜲䝹䛾ᆺ䚸ᚄ䛿䚸㉳☢ຊ䛾ቑຍ䛻䜘 䜛㟁☢ຊ䛾ቑ䛸䛒䛔䜎䛳䛶ኚᙧ䛾ᙳ㡪䜢ཷ䛡䜔䛩 䛔୍᪉䚸䛭䛾ᣲື䛾ィ 䛜ᅔ㞴䛷䚸䝁䜲䝹䛾䜽䜶䞁 䝏⪏ᛶ䛻ᑐ䛩䜛᳨ウ䜢䛧䛻䛟䛟䛩䜛䚹䛭䛣䛷䝃䞊䝏䝁 䜲䝹5)6)䛸䝁䜲䝹୧➃㟁ᅽ7)䛾ィ 䝕䞊䝍䜢㢮ᆺ䛩 䜛䛣䛸䛷䝁䜲䝹ᣲື䛸䜽䜶䞁䝏䛾㛵ಀ䜢ゎ᫂䛧䚸䜽䜶䞁 䝏䝸䝇䜽䜢పῶ䛩䜛䛯䜑䛾ᣦ㔪䜢ᥦ䛩䜛䚹 㻞㻚㻌 ᙉ☢ᛶయ䛸䝁䜲䝹䜢ే⏝䛧䛯㻹㻾㻵⏝㉸㟁ᑟ☢▼ 䛾☢Ẽタィ㻤㻕㻥㻕㻌 ᮏ❶䛷䛿䚸᭱ึ䛾ᢏ⾡ㄢ㢟䛸䛧䛶䚸㧗㛤ᨺᆺMRI ⏝㉸㟁ᑟ☢▼䛻ዲ㐺䛺☢Ẽタィᡭἲ䜢ᵓ⠏䛧䚸タ ィୖ䛾ᣦ㔪䜢♧䛩䛣䛸䜢䜑䛦䛧䛯䚹䛣䛾┠ⓗ䜢㐩ᡂ 䛩䜛䛯䜑䚸䝁䜲䝹䛾䜏䛻䜘䜙䛪䚸㕲䛺䛹䛾☢ᛶయ䜢ే ⏝䛧䛶ᆒ୍☢ሙ✵㛫䜢⏕ᡂ䛩䜛䛣䛸䛷䝁䜲䝹ᩘ䛜ቑ 䛘䛯䜚㉳☢ຊ㓄⨨䛜」㞧䛻䛺䛳䛯䜚䛩䜛䛣䛸䜢㑊䛡䜛 䛸䛔䛖䜰䝥䝻䞊䝏䜢䛸䛳䛯䚹 MRI⏝㉸㟁ᑟ☢▼䛾䜘䛖䛻䚸ᆒ୍䛺ᙉ☢ሙ✵㛫䜢 ௵ព䛾✵㛫䛾㟁ὶ䜔☢Ẽ䝰䞊䝯䞁䝖䜢⏝䛔䛶ᐇ⌧䛩 䜛䛯䜑䛾ᡭἲ䛸䛧䛶䛿䚸≉␗್ศゎἲ䜢⏝䛔䛯㏫ၥ 㢟ゎἲ䛜᭷ຠ䛷䛒䜛䛣䛸䛜▱䜙䜜䛶䛚䜚10)䚸䛣䛾ᡭἲ
䛻ᇶ䛵䛟䝥䝻䜾䝷䝮䜢⥲⛠䛧䛶DUCAS (Design tools Using Current potential And Svd) 䛸䜣 䛷䛔䜛䚹 DUCAS䛾ᡭἲ䛿䚸᪉⛬ᘧ䜢⥺ᙧ䛻グ㏙䛷䛝䜛⠊ᅖ 䛷㠀ᖖ䛻ᙉຊ䛺᭱㐺ᡭẁ䜢ᥦ౪䛩䜛୍᪉䛷䚸㠀 ⥺ᙧᛶ䛜ᙉ䛛䛳䛯䜚䚸ไ⣙᮲௳䜢⪃៖䛩䜛ᚲせ䛜䛒 䛳䛯䜚䛩䜛㝿䛾㐺⏝䛻㞴䛧䛥䛜䛒䜛䚹䛭䛣䛷ᮏ◊✲䛷 䛿䚸䛣䛾ᡭἲ䜢䚸☜⋡ⓗ᥈⣴ᡭἲ䛷䛒䜛↝䛝䛺䜎䛧ἲ 䛻䜘䜛᭱㐺₇⟬䛾ホ౯㛵ᩘ䛸䛧䛶ྲྀ䜚㎸䜐䛣䛸䛷䚸 㕲䛸䝁䜲䝹䜢ే⏝䛧䛯MRI⏝☢▼䛾ᆒ୍☢ሙタィ䛾 ᐇ⌧䜢≺䛖䚹 Ⓒ 2021 東北大学電気通信研究所
㕲䛺䛹䛾☢ᛶయ䛜䛴䛟䜛☢Ẽ䝰䞊䝯䞁䝖䛾ศᕸศ ᕸࡹ䛜ീ✵㛫䛻స䜛☢ሙศᕸ䛿䚸⾜ิܣ䜢⏝ 䛔䛶䚸 = ܣࡹ (1) 䛾䜘䛖䛻⾲⌧䛥䜜䜛䚹䛣䜜䜢≉␗್ศゎἲ䛻䜘䜚ศゎ 䛧䛶⾲⌧䛩䜛䛸䚸䛣䛾㐃❧᪉⛬ᘧ䛾ゎ䛿㻌 ࡹ = ܸܹᇱ்ܷ (2) ܯ= ቊݒݓ (࢛ή )ቋ ೌೣ ୀଵ (3) 䛾䜘䛖䛻᭩䛛䜜䚸݆௫䜢㐺ษ䛻㑅ᐃ䛩䜛䛣䛸䛷௵ព䛾 ⢭ᗘ䛷ࡹ䜢ᚓ䜛䛣䛸䛜䛷䛝䜛䚹䛣䛾䜘䛖䛺ᐃᘧ䛻䜘 䜜䜀䚸ࡹ䛾せ⣲䛾䛖䛱䚸᭱䛾䜒䛾䜢ܯ୫ୟ୶䚸᭱ᑠ䛾䜒 䛾䜢ܯ୫୧୬䛸䛩䜛䛸䛝䚸ᆒ୍☢ሙศᕸ䜢ᚓ䜛䛯䜑䛾☢ ᛶయ䛾≀㔞䛿䚸 οܯ = ܯ୫ୟ୶െ ܯ୫୧୬ (4) 䛺䜛ᙧᘧ䛷⾲⌧䛥䜜䜛䚹ᮏ◊✲䛷䛿䚸䛣䛾䜘䛖䛻䛧䛶 ᚓ䜙䜜䜛οܯ䜢┠ⓗ㛵ᩘ䛸䛩䜛᭱㐺ၥ㢟䜢ᐃ⩏ 䛧䚸↝䛝䛺䜎䛧ἲ䛻䜘䜛᭱㐺䛾ホ౯㛵ᩘ䛸䛧䛶⤌ 䜏㎸䜣䛰䚹₃ὤ☢ሙ䜔㉸㟁ᑟ䝁䜲䝹䛾᭱⤒㦂 ☢ሙ䛺䛹䛾ไ⣙᮲௳䛿䚸㐓⬺䛧䛯㝿䛻┠ⓗ㛵ᩘ 䜈䝨䝘䝹䝔䜱䛸䛧䛶ຍ⟬䛩䜛䝨䝘䝹䝔䜱ἲ䛻䜘䜚⪃ ៖䛧䛯䚹 䛣䛾䜘䛖䛻ᵓ⠏䛧䛯☢Ẽタィᡭἲ䜢⏝䛔䛯MRI⏝ ㉸㟁ᑟ☢▼䛾ヨタィ䜢⾜䛳䛯䚹䜎䛪䚸ᅗ1䛻♧䛩䜘䛖 䛺䚸䝺䞊䝇䝖䝷䝑䜽≧䛾䝁䜲䝹䜢⏝䛔䛶ᶓ᪉ྥ䛻㛗䛔 ✵㛫䜢స䜛䛣䛸䛜䛷䛝䜛య⣔䛻ᮏᡭἲ䜢㐺⏝䛧䛯䚹䛣 䛾⤖ᯝ䚸㏻ᖖ䛾ᙧ䝁䜲䝹䜢⏝䛔䛯Ỉᖹ☢ሙᆺMRI ⏝㉸㟁ᑟ☢▼䛸ྠ➼䛾8ಶ䛾䝁䜲䝹䛸㕲䛸䛾⤌䜏ྜ 䜟䛫䛷䚸ᅗ2䛻♧䛩䜘䛖䛻䚸ᐇ⏝ⓗ䛺ᆒ୍✵㛫䜢ᚓ䜛 䛣䛸䛻ᡂຌ䛧䛯䚹 ḟ䛻䚸䜘䜚㧗㛤ᨺ䛺☢▼ᙧ≧䜢ᚓ䜛䛣䛸䜢䜑䛦䛧䚸 ᅗ3䛻♧䛩䜘䛖䛺య⣔䜈䛾㐺⏝䜢ヨ䜏䛯䚹䛯䛰䛧䚸ᅗ 1䛾䜘䛖䛺య⣔䛷䛿䚸」ᩘ(䛣䛾ሙྜ8ಶ)Ꮡᅾ䛩䜛㉸ 㟁ᑟ䝁䜲䝹䛾⨨䜔ᙧ≧䜢᭱㐺䝟䝷䝯䞊䝍䛸䛧䚸䛭 䛾Ⰻ䛧ᝏ䛧䜢ᘧ(4)䛻䜘䜚ホ౯䛧䛯䛜䚸ᅗ3䛾య⣔䛷䛿 䝁䜲䝹䛿ୖୗ1ᑐ䛾2ಶ䛧䛛䛺䛟䚸᭱㐺䝟䝷䝯䞊䝍䛜 ㊊䛩䜛䚹䛭䛣䛷䚸䝟䝷䝯䞊䝍䛾㊊䜢⿵䛖䛯䜑䛻☢ ᛶయ䛾พฝᙧ≧(☢ᴟᙧ≧)䜢⏝䛔䛶ᆒ୍✵㛫䜢⏕ ᡂ䛩䜛䛣䛸䛸䛧䚸䛛䛴䚸↝䛝䛺䜎䛧ἲ䛾䛒䛸䛻ᘬ䛝⥆䛔 䛶ᨵ䜑䛶DUCAS䛾ᡭἲ䜢⏝䛔䛶☢ᴟᙧ≧䜢᭱⤊ 䛩䜛䛸䛔䛖ᡭἲ䛾ಟṇ䜢⾜䛳䛯䚹 䛣䛾⤖ᯝ䚸ᅗ4䛻♧䛩䜘䛖䛺ᙧ≧䛷ᆒ୍☢ሙ䜢ᚓ 䜛䛣䛸䛻ᡂຌ䛧䛯䚹 䛣䛾䜘䛖䛻䚸ᆒ୍☢ሙ䜢䚸䝁䜲䝹䛸㕲䛸䜢ే⏝䛩䜛䛣 䛸䛷ᚓ䜛䛯䜑䛻䛿䚸䝁䜲䝹ᩘ䛾䜘䛖䛺᭱㐺䝟䝷䝯䞊 ᅗ1 ࣮ࣞࢫࢺࣛࢵࢡ≧ࢥࣝ㕲ࢆే⏝ࡋࡓ MRI ⏝㉸㟁ᑟ☢▼ࡢయ⣔ ᅗ2 ࣮ࣞࢫࢺࣛࢵࢡ≧ࢥࣝ㕲ࢆే⏝ࡋࡓ MRI ⏝㉸㟁ᑟ☢▼ࡢヨタィ⤖ᯝ ☢ሙᙉᗘ[T] 1.50001 1.50000 z y x 㕲∦ 䝁䜲䝹 10μT/line ᅗ3 ᆶ┤☢ሙᆺ MRI ⏝㉸㟁ᑟ☢▼ࡢయ⣔ ᅗ4 ᆶ┤☢ሙᆺ MRI ⏝㉸㟁ᑟ☢▼ࡢヨタィ ⤖ᯝ
䝍䛾ከᐻ䛻ᛂ䛨䛶☢Ẽタィᡭἲ䜢㑅ᐃ䛧㐺⏝䛩䜛䛣 䛸䛜᭷ຠ䛺タィᣦ㔪䛸䛺䜛䛣䛸䛜᫂䜙䛛䛻䛺䛳䛯䚹 㻟㻚㻌 ᕳ䝁䜲䝹䛻䜘䜛㻹㻾㻵⏝㉸㟁ᑟ☢▼䛾☢ሙᏳᐃ 㻝㻝㻕㻌 ᮏ❶䛷䛿䚸㧗㛤ᨺᆺ䚸䛸䜚䜟䛡ᆶ┤☢ሙᆺ䛾MRI ⏝㉸㟁ᑟ☢▼䛷㢧ᅾ䛧䜔䛩䛔እ(እ᮶)☢ሙ䛾 ධ䛻䜘䜛MRI⨨䛾⏬㉁䛾ຎ䛸䛔䛖ᢏ⾡ㄢ㢟䜢 ゎỴ䛩䜛䛣䛸䜢䜑䛦䛧䛯䚹䛣䛾䛯䜑䛾ᵓᡂ䛸䛧䛶䚸 ᕳ䝁䜲䝹䛛䜙䛺䜛㛢䝹䞊䝥䜢㉸㟁ᑟ☢▼䛻ෆⶶ䛩䜛 እ☢ሙᢚไ䝁䜲䝹䜢ᥦ䛧䚸ヨస䛻䜘䛳䛶䛭䛾ື స䜢᳨ド䛧䛯䚹 ᅗ5䛻ヨసヨ㦂య⣔䛾䜂䛸䛴䜢♧䛩䚹ບ☢䝁䜲䝹 ⣔䜢ᶍᨃ䛧䛯䜸䝣䝉䝑䝖☢ሙ༳ຍ⏝䝁䜲䝹䛜Ⓨ⏕䛩 䜛ᙉ☢ሙୗ䛻እ☢ሙᢚไ䝁䜲䝹䜢㓄⨨䛩䜛䚹䛭䛾 ᕳ⥺ἲ䛚䜘䜃ᅛᐃἲ䜢䝟䝷䝯䞊䝍䛸䛧䚸እ☢ሙ༳ ຍ䝁䜲䝹䛻䜘䜚༳ຍ䛥䜜䜛☢ሙ䛜䝩䞊䝹⣲Ꮚ⨨䛷 タィ㏻䜚䛻ᢚไ䛥䜜䜛䛛䛻䛴䛔䛶ヨ㦂䜢⾜䛳䛯䚹 ᅗ6䛻ヨ㦂⤖ᯝ䜢♧䛩䚹ᐦᕳ䝁䜲䝹䛷䛒䜛䝃䞁䝥 䝹2b䚸䝔䞁䝅䝵䞁ᕳ䜢䛧䛯ᕳ䝁䜲䝹䛷䛒䜛䝃䞁䝥 䝹2a䛷䛿䚸ᙉ☢ሙୗ䛻䛚䛔䛶䜒እ☢ሙᢚไᛶ⬟ 䛜ຎ䛧䛺䛛䛳䛯䛜䚸䝔䞁䝅䝵䞁ᕳ䜢䛧䛺䛔➼䛻䜘䜚 ┦ᑐⓗ䛻ᕳ⥺ᅛᐃ䛜⏑䛔ᕳ䝁䜲䝹䛷䛒䜛䝃䞁䝥䝹 1䛷䛿䚸䜸䝣䝉䝑䝖☢ሙ༳ຍ䛻క䛔䛝䛺ᛶ⬟ຎ䜢 ㉳䛣䛩䛣䛸䛜☜ㄆ䛥䜜䛯䚹 ⪃ᐹ䛾⤖ᯝ䚸䛣䛾ᛶ⬟ຎ䛿䚸እ☢ሙᢚไ䝁䜲 䝹䛾ᕳ⥺䛜㟁☢ຊ䛻䜘䜚μm䜸䞊䝎䞊䛾ኚ䜢㉳䛣 䛩䛣䛸䛷㙐☢᮰ኚ䜢ᡴ䛱ᾘ䛩䛣䛸䛜ཎᅉ䛷䛒䜛 䛣䛸䚸䛣䛾ኚ䛾⛬ᗘ䛿䚸䜲䞁䝎䜽䝍䞁䝇䛾ḟඖ䜢ᣢ 䛴㔞ܸ䛷⾲⌧䛷䛝䜛䛣䛸䛜䜟䛛䛳䛯䚹 䛣䜜䛻䜘䜚䚸እ☢ሙᢚไ䝁䜲䝹䛜ᙉ☢ሙୗ䛷䜒 ᛶ⬟ຎ䜢㉳䛣䛥䛺䛔䛯䜑䛾タィᣦ㔪䛜௨ୗ䛾䜘䛖 䛻♧䛥䜜䛯䚹ບ☢䝁䜲䝹⣔䛾⮬ᕫ䜲䞁䝎䜽䝍䞁䝇䜢ܮ䚸 እ☢ሙᢚไ䝁䜲䝹⣔䛾⮬ᕫ䜲䞁䝎䜽䝍䞁䝇䜢ܮ௦䚸ບ ☢䝁䜲䝹⣔䛸እ☢ሙᢚไ䝁䜲䝹⣔䛸䛾┦䜲䞁䝎䜽 䝍䞁䝇䜢ܯ௦䛸䛩䜛䚹እ☢ሙ䛜☢▼࿘ᅖ䛻⌧䜜䚸ບ ☢ 䝁 䜲 䝹 ⣔ 䚸 እ ☢ ሙ ᢚ ไ 䝁 䜲 䝹 ⣔ 䛻 㙐 ☢ ᮰ ߶, ߶௦䛜⏕䛨䜛䛸䚸ྛ䚻䛾䝁䜲䝹⣔䛾☢᮰ಖᏑຠᯝ䛻 䜘䛳䛶ㄏᑟ㟁ὶοܫ, ȟܫ௦䛜⏕䛨䜛䚹䛣䛾䛸䛝䚸☢᮰ಖᏑ 䛾ᘧ䛿䚸௨ୗ䛾䜘䛖䛻᭩䛡䜛䚹 ൬ܮ ܯ௦ ܯ௦ ܮ௦+ ܸ൰ ൬οܫ οܫ௦൰ = ൬߶ ߶௦൰ (5) ᘧ(5)䛻䜘䜜䜀䚸ȟܫ௦䛜ܸ䛾ᙳ㡪䜢ཷ䛡䛺䛔䛸䜏䛺䛫䚸 ᙉ☢ሙୗ䛻䛚䛔䛶䜒ᡤᮃ䛾ᛶ⬟䜢ᚓ䜙䜜䜛䜘䛖䛻䚸 䛯䛸䛘䜀䚸ܸ䛜ܮௌ䛾1/10௨ୗ䚸䛸䛔䛖䜘䛖䛻䚸ܸا ܮ௦ 䛸䛺䜛䜘䛖䛺እ☢ሙᢚไ䝁䜲䝹䛾タィ䛜᭷ຠ䛷䛒䜛 䛣䛸䛜᫂䜙䛛䛻䛺䛳䛯䚹 㻠㻚㻌 ㉸㟁ᑟ☢▼䛾ບ☢୰䛾䝁䜲䝹ኚ≉ᛶ䛸䜽䜶䞁 䝏㜵Ṇᵓ㐀㻝㻞㻕㻌 ᮏ❶䛷䛿䚸ᆶ┤☢ሙᆺ䛾MRI⏝㉸㟁ᑟ☢▼䛷 䛝䛺ᢏ⾡ㄢ㢟䛸䛺䜛䚸㟁☢ຊ䛻䜘䜛ኚᙧ䛻௦⾲䛥䜜䜛 䝁䜲䝹ᣲື䛸䜽䜶䞁䝏䛾㛵ಀ䜢ゎ᫂䛧䚸䜽䜶䞁䝏䝸䝇䜽 䜢పῶ䛩䜛䛯䜑䛾ᣦ㔪䜢ᥦ䛩䜛䛣䛸䜢䜑䛦䛧䛯䚹䛣 䛾䛯䜑䛻䚸☢▼䛻タ⨨䛧䛯䝃䞊䝏䝁䜲䝹䛚䜘䜃㟁ᅽ ➃Ꮚ䜢⏝䛔䛯ィ 䝕䞊䝍䜢ศᯒ䛩䜛䛣䛸䛷䝁䜲䝹ᣲ ື䜢᫂䜙䛛䛻䛧䚸䛭䛾䜽䜶䞁䝏䛸䛾㛵㐃䜢ㄪ䜉䜛䛸䛔 䛖䜰䝥䝻䞊䝏䜢䛸䛳䛯䚹 ᅗ7䛻ヨ㦂య⣔䜢♧䛩䚹ୖഃ䝁䜲䝹䛸ୗഃ䝁䜲䝹䛭 䜜䛮䜜䛻4ಶ䛪䛴䝃䞊䝏䝁䜲䝹䜢㓄⨨䛧䚸䛛䛴䚸䝁䜲 ᅗ5 እ☢ሙᢚไࢥࣝࡢヨ㦂య⣔ ᅗ6 እ☢ሙᢚไࢥࣝࡢヨ㦂⤖ᯝ ࢜ࣇࢭࢵࢺ☢ሙᙉᗘ>7@ እ☢ሙᢚไ⋡4>@ ࢧࣥࣉࣝ ࢧࣥࣉࣝD ࢧࣥࣉࣝE ᅗ7 ࢥࣝᣲືศᯒࡢࡓࡵࡢヨ㦂య⣔ ୖഃ䝁䜲䝹 ୗഃ䝁䜲䝹 x z (䝃䞊䝏䝁䜲䝹)☢Ẽ䝉䞁䝃 㐃⤖ᰕ φ2000 x (0 deg) y (90 deg) 30 deg 90 deg ୖഃ 䝁䜲䝹 ୗഃ 䝁䜲䝹 ↑ 㟁※ VUPPER VLOWER
䝹୧➃䛻䛿䛭䜜䛮䜜㟁ᅽ➃Ꮚ䜢タ䛡䛯䚹䛣䛾䜘䛖䛺 య⣔䛻䛚䛔䛶䚸ບ☢㐣⛬䛻䛶䛭䜜䛮䜜䛾ィ 䛷ᚓ 䜙䜜䛯Ἴᙧ䜢㛫᪉ྥ䛻✚ศ䛧䛶㙐☢᮰ኚ䜢 ồ䜑䚸䝃䞊䝏䝁䜲䝹Ἴᙧ䛚䜘䜃䛭䜜䛻ᑐᛂ䛩䜛䝁䜲 䝹୧➃㟁ᅽἼᙧ䜢⤌䜏ྜ䜟䛫䚸㢮ᆺ䛧䛯䚹䛣䛾⤖ ᯝ䚸⣙400䛾䝃䞊䝏䝁䜲䝹Ἴᙧ䛸ᑐᛂ䛜ྲྀ䜜䛯12䛾 䝁䜲䝹୧➃㟁ᅽἼᙧ䛿䚸ᆺⓗ䛻䛿䚸≉ᚩⓗ䛺Ἴᙧ 2✀㢮䛻㢮ᆺ䛥䜜䜛䛣䛸䛜䜟䛛䛳䛯䚹䛥䜙䛻䛭䛾䛖䛱䚸 ㉸㟁ᑟ䝁䜲䝹䛜䜽䜶䞁䝏䛧䛯㝿䛾Ἴᙧ䛻䛚䛔䛶䛿䚸 ィ 䛥䜜䛯Ἴᙧ䛿䚸๓グ2✀㢮䛾䛖䛱䛾1✀㢮䛻㝈䜙 䜜䜛䛣䛸䜢ぢฟ䛧䛯䚹ᅗ8䛻䚸䛣䛾㢮ᆺ䛾䛖䛱䚸㟁ᅽಙ ྕ䛾㛫✚ศἼᙧ䛾ᆺⓗ䛺䜢♧䛩䚹 䛣䜜䜙㢮ᆺ䛻䛴䛔䛶⪃ᐹ䛧䛯⤖ᯝ䚸ᅗ8䛻ぢ䜙䜜䜛 䜘䛖䛺≉ᚩⓗ䛺ಙྕἼᙧ䛿䚸䝁䜲䝹䛾㍈᪉ྥኚ䛸 ᚄ᪉ྥኚ䛸䛜ྠ䛻⏕䛨䛯䛸䛝䛻⌧䜜䚸䜽䜶䞁䝏 䛻㛵ಀ䛧䛺䛔䜒䛖୍᪉䛾㢮ᆺ䛷䛿䚸䛣䛾䛖䛱䚸㍈᪉ྥ ኚ䛜⏕䛨䛶䛔䛺䛔䛣䛸䛜䜟䛛䛳䛯䚹 䛩䛺䜟䛱䚸䛣䛾䜘䛖䛺య⣔䛾䝁䜲䝹䛷䛿䚸㍈᪉ྥ䛾 ኚ䛜䜽䜶䞁䝏䜢ᘬ䛝㉳䛣䛧䛶䛔䜛䛣䛸䜢ᙉ䛟♧၀䛩 䜛䚹䛭䛣䛷䚸䛣䜜䜢㜵䛠䚸䛒䜛䛔䛿䛣䜜䛻⪏䛘䜛䛯䜑䛻䚸 ᅗ9䛻♧䛩䜘䛖䛻䚸䝁䜲䝹䜢ᦾືⓎ⇕䛛䜙Ᏺ䜛᩿⇕ᒙ (⤯⦕ᒙ䜢ව䛽䜛)䛾እഃ䛷✚ᴟⓗ䛻㍈᪉ྥ䛻ᦾື 䛥䛫䜛䛣䛸䛷ᦾືⓎ⇕䜢チᐜ䛧䛴䛴䛣䜜䜢᩿⇕䛧䚸䛛 䛴䚸䝁䜲䝹ഃ㠃䛾⤯⦕ᯈ䜢ෆ࿘ഃ䛾⤯⦕∧䛻✺䛝ᙜ 䛶䜛ᵓ㐀䛻䛩䜛䛣䛸䛷⤯⦕ᯈ䛾䜈䛝㛤ຊ䛻䜘䜛㞳 䜔䝰䞊䝹䝗ᶞ⬡䛾◚ቯ䜢㜵䛠᪉ἲ䜢⪃䛧䛯13)䚹䛭 䛧䛶䚸䛣䛾䜘䛖䛺タィᣦ㔪䛻ᇶ䛵䛟䛣䛸䛷⪏䜽䜶䞁䝏 ᛶ⬟ୖ᭷ຠ䛺ᡭἲ䛸䛺䜚䛖䜛䛣䛸䜢♧䛧䛯䚹 㻡㻚㻌 䜎䛸䜑㻌 ᮏ◊✲䛷䛿䚸㧗㛤ᨺᆺMRI⏝㉸㟁ᑟ☢▼䛻ᚲせ 䛺㧗ᆒ୍䛛䛴㧗Ᏻᐃ䛺ᙉ☢ሙ䛾ᐇ⌧䛾3䛴䛾ᢏ⾡ ㄢ㢟䜢タᐃ䛧䛯䚹䝁䜲䝹䛸☢ᛶయ䛸䜢ే⏝䛧䛶ᆒ୍☢ ሙ䜢⏕ᡂ䛩䜛䛯䜑䛾᪂䛧䛔☢Ẽタィᡭἲ䛾ᵓ⠏䚸እ ᮶☢ሙ䛾ᢚไᡭἲ䛾ᥦ䛸䛭䛾タィᣦᶆ䛾ᑟฟ䚸 䜽䜶䞁䝏ᶵᗎ䛾ゎ᫂䛸䛭䛾ᑐ⟇ᵓ㐀䛾ᥦ䛻䜘䜚䛣 䜜䜙䛾ᢏ⾡ㄢ㢟䜢ゎỴ䛧䚸ᆒ୍䛛䛴Ᏻᐃ䛺ᙉ☢ሙ䜢 ᐇ⌧䛩䜛䛯䜑䛾ᢏ⾡ᡭẁ䛸タィᣦ㔪䜢ᵓ⠏䛧䛯䚹䛣 䛾ᣦ㔪䛻ᇶ䛵䛟䛣䛸䛻䜘䜚䚸㧗㛤ᨺ䛺MRI⏝㉸㟁ᑟ ☢▼䛾タィ䛜䜘䜚ᐜ᫆䛻⾜䛘䜛䜘䛖䛻䛺䛳䛯䚹 ᚋ䛿䚸䜽䜶䞁䝏䛾䝁䜲䝹ኚ䛸䛭䛾䝯䜹䝙䝈䝮 䜢⤫ィⓗ䛻䜘䜚᫂☜䛻䛩䜛䛯䜑䛾䚸┤᥋ほ 䛻䜘䜛 ⌧㇟ゎ᫂䛜㔜せ䛺◊✲ㄢ㢟䛸⪃䛘䜙䜜䜛䚹䛣䜜䛻ᚲ せ䛸䛺䜛ከ䛟䛾⤫ィ䝕䞊䝍䛾ྲྀᚓ䛾䛯䜑䛾ᗮ౯䛺ヨ 㦂య⣔14)䜔䚸䛥䜙䛺䜛ヲ⣽ィ 䛻䜘䜛⌧㇟䛾⌮ゎ䛻䚸 ᮏ◊✲䛜䛭䛾୍ຓ䛸䛺䜛䛣䛸䛜ᮇᚅ䛥䜜䜛䚹 ᩥ⊩
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28 (2018). ᅗ8 ࢥࣝࢡ࢚ࣥࢳ㛵㐃ࡍࡿ㟁ᅽἼᙧ㢮ᆺ 㻙㻜㻚㻜㻜㻜㻤 㻙㻜㻚㻜㻜㻜㻠 㻜㻚㻜㻜㻜㻜 㻜㻚㻜㻜㻜㻠 㻜㻚㻜㻜㻜㻤 㻜 㻜㻚㻜㻝 㻜㻚㻜㻞 㻜㻚㻜㻟 㻜㻚㻜㻠 㻜㻚㻜㻡 㛫㻌㼇㼟㼉 ✚ศ್㻌㼇㼂 㼟㼉 䛝䛟䜜䛶䛛䜙 䜒䛸䛻ᡠ䜛 -0.8 -0.4 0 0.4 0.8 㟁ᅽ✚ศ್ [m Vs ] 0.04 0.05 㛫[s] 0 0.01 0.02 0.03 ṇᴟഃ ㈇ᴟഃ ᅗ9 ㍈᪉ྥኚࡼࡿᶵᲔᨐࡢᢚไᵓ㐀
