GB2454475A - A Heat Shield for an MRI scanner - Google Patents
A Heat Shield for an MRI scanner Download PDFInfo
- Publication number
- GB2454475A GB2454475A GB0721799A GB0721799A GB2454475A GB 2454475 A GB2454475 A GB 2454475A GB 0721799 A GB0721799 A GB 0721799A GB 0721799 A GB0721799 A GB 0721799A GB 2454475 A GB2454475 A GB 2454475A
- Authority
- GB
- United Kingdom
- Prior art keywords
- heat shield
- conductive elements
- shield
- heat
- electrically insulating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000001816 cooling Methods 0.000 claims abstract description 24
- 239000012777 electrically insulating material Substances 0.000 claims abstract description 11
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910052802 copper Inorganic materials 0.000 claims abstract description 10
- 239000010949 copper Substances 0.000 claims abstract description 10
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 239000000463 material Substances 0.000 abstract description 13
- 230000005855 radiation Effects 0.000 abstract description 11
- 239000004033 plastic Substances 0.000 abstract description 4
- 229920003023 plastic Polymers 0.000 abstract description 4
- 239000004020 conductor Substances 0.000 abstract description 3
- 230000015572 biosynthetic process Effects 0.000 abstract description 2
- 229910052734 helium Inorganic materials 0.000 description 10
- 239000001307 helium Substances 0.000 description 10
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 10
- NMFHJNAPXOMSRX-PUPDPRJKSA-N [(1r)-3-(3,4-dimethoxyphenyl)-1-[3-(2-morpholin-4-ylethoxy)phenyl]propyl] (2s)-1-[(2s)-2-(3,4,5-trimethoxyphenyl)butanoyl]piperidine-2-carboxylate Chemical compound C([C@@H](OC(=O)[C@@H]1CCCCN1C(=O)[C@@H](CC)C=1C=C(OC)C(OC)=C(OC)C=1)C=1C=C(OCCN2CCOCC2)C=CC=1)CC1=CC=C(OC)C(OC)=C1 NMFHJNAPXOMSRX-PUPDPRJKSA-N 0.000 description 7
- 238000002595 magnetic resonance imaging Methods 0.000 description 4
- 238000001746 injection moulding Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229920002799 BoPET Polymers 0.000 description 2
- 239000005041 Mylar™ Substances 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 238000009954 braiding Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C13/00—Details of vessels or of the filling or discharging of vessels
- F17C13/001—Thermal insulation specially adapted for cryogenic vessels
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/3804—Additional hardware for cooling or heating of the magnet assembly, for housing a cooled or heated part of the magnet assembly or for temperature control of the magnet assembly
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/381—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using electromagnets
- G01R33/3815—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using electromagnets with superconducting coils, e.g. power supply therefor
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F6/00—Superconducting magnets; Superconducting coils
- H01F6/04—Cooling
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2203/00—Vessel construction, in particular walls or details thereof
- F17C2203/03—Thermal insulations
- F17C2203/0304—Thermal insulations by solid means
- F17C2203/0308—Radiation shield
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2209/00—Vessel construction, in particular methods of manufacturing
- F17C2209/23—Manufacturing of particular parts or at special locations
- F17C2209/232—Manufacturing of particular parts or at special locations of walls
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2270/00—Applications
- F17C2270/05—Applications for industrial use
- F17C2270/0527—Superconductors
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
A radiation shield for a MRI scanner housing is formed of a plurality of thermally conductive tracks interspaced by electrically insulating material (e.g a plastics material) which are formed to provide heat conduction paths to a cooling area of the shield. The amount of conductive material used, for example copper, is reduced and the formation of eddy currents prevented or at least reduced.
Description
A Radiation Shield And A MaQnetic Resonance lmaciing Scanner This invention relates to a Magnetic Resonance Imaging scanner and in particular to a shield for such a scanner which minimises heating of helium held within a housing of the scanner.
Magnetic Resonance Imaging (MRI) scanners utilise large superconducting magnets which require cooling to liquid helium temperatures for successful operation. A containment structure is provided to enclose the magnets and to hold a large volume of the liquid helium to provide the cooling. Liquid helium is very expensive and thus the structure is designed to minimise its loss through heating from the environment where the scanner is located. A multilayer structure is provided which is designed to prevent heat passing into the helium by conduction, convection and radiation.
The structure comprises a helium vessel which is innermost, a radiation shield spaced apart from the helium vessel, a number of layers of aluminised Mylar foil and insulation mesh, and then the outer vessel. This structure is evacuated during manufacture to minimise heat transfer from the outer vessel by convection.
The radiation shield is formed of a high grade aluminium to provide a highly reflective surface to minimise radiation of heat into the inner helium vessel. A problem with such shields is that they permit the generation of eddy currents which oppose the field produced by the scanner magnets leading to in-efficiencies and, in particular, may make the interpretation of the scan more difficult particularly if the eddy currents are not evenly distributed.
The present invention arose from the realisation that the material used in the heat shield could be tailored to provide the required heat conduction properties whilst minimising the generation of eddy currents.
According to the invention there is provided a heat shield for a MRI scanner comprising a plurality of conductive elements interspaced by an electrically insulating material which conductive elements aligned to provide heat conduction paths to at least one cooling area, in use, coupled to a cooling source.
By providing electrically insulating material interspacing the conductive elements, eddy currents are prevented from flowing across the conductive elements. The conductive elements still assist in the cooling of the radiation shield by being aligned with the desired heat conduction paths to the cooling area. Preferably, the conductive elements are metal. In the described embodiment copper is used embedded in a plastics material. There is also less conductive material used in the shield which further reduces the formation of eddy currents, weight and cost.
In the described embodiment, there is one cooling area but there could be two or more cooling areas.
The material may be made by an injection moulding process and then the moulded material taken and formed into the shield. Alternatively, it will be advantageous to form the shield from the material by direct injection moulding.
A specific embodiment of the invention will now be described, by way of example only, with reference to the drawing in which: Figure 1 shows a radiation shield for a scanner in accordance with the invention; Figure 2 shows an enlarged view of part of the surface of the radiation shield shown in figure 1.
As is shown in figure 1, a radiation shield 1 of a Magnetic Resonance Imaging scanner is formed as a generally cylindrical annular structure with two annular end faces 2, 3 one of which is visible, an inner cylinder 4 and an outer cylinder 5.
Within the shield 1 is located a helium vessel containing helium to cool a set of superconducting magnets (not shown). About the shield 1 is located a number of insulation layers of reflective Mylar material and insulating mesh 6 and an outer containment vessel 7 also of generally cylindrical configuration. The radiation shield I is contained within a vacuum in the outer containment vessel 7.
A refrigeration unit (not shown) supplies coolant to a cooling head 8 in good thermal contact to a cooling area on the shield 1. This maintains the shield I at a temperature, when in use, of about 52 Kelvin.
There will exist a temperature gradient from the cooling area to the lower part of the shield 1 and hence the heat will be conducted in the direction of the arrows flowing circumferentially from the lower part of the shield to the cooling area at the top of the shield. The invention arose from a realisation by the inventors that it is desirable to provide material aligned with the flow paths to provide the conduction but that it is not necessary to promote flow paths in direction at an angle to them. Thus, the shield 1 is formed from a material of copper tracks embedded in electrically insulating material which maximise conduction material to provide the circumferential flow paths. The electrically insulating material reduces the amount of conductive material at an angle to the flow paths and prevents the creation of eddy currents.
The material is shown in greater detail in figure 2 which is an enlargement of area labelled II. Area II shows that the shield 1 is formed by an injection moulding technique in which a large number of copper tracks 20 embedded and separated by an insulating plastics material 21. The copper tracks 20 extend in the circumferential direction to encourage heat flow in the desired circumferential paths to the cooling area and cooling head 8. The insulating plastics material 21 prevents eddy currents flowing between the copper tracks 20 and also reduces the amount of copper matenal used which in turn reduces the eddy currents further. A low emissivity coating 22 is applied which is shown partially removed for the purposes of illustration. This provides a reflective surface to the heat shield to prevent heat absorption from the external environment. This may be sprayed on or applied as an adhesive tape or applied in other ways.
In this embodiment the end faces 2, 3 are formed from high grade aluminium but in alternative embodiments may be itself formed of conductive tracks interspaced by insulating material. These may be formed to provide conduction paths which flow generally upwards about the annulus as shown by the flow arrows depicted on the end face 2.
To assist efficient cooling at the cooling area, the copper tracks 20 may be linked in that region and braiding provided for coupling the tracks to the cooling head 8.
In the described embodiment, the conductive tracks are provided as one layer but it will be appreciated that they may be over-wound to provide multiple layers extending outwardly in a radial direction from an axis of the scanner.
Claims (7)
- Claims 1. A heat shield for a MRI scanner comprising a plurality of conductive elements interspaced by an electrically insulating material which conductive elements aligned to provide heat conduction paths to at least one cooling area, in use, coupled to a cooling source.
- 2. A heat shield as claimed in claim 1 wherein the conductive elements are formed of a metal.
- 3. A heat shield as claimed in claim 2 wherein the metal is copper.
- 4. A heat shield as claimed in any preceding claim wherein a low emissivity layer is applied over the conductive elements and electrically insulating material to prevent heat transfer to the shield.
- 5. A heat shield as claimed in any preceding claim wherein the conductive elements extend circumferentially about the heat shield.
- 6. A heat shield as claimed in any preceding claim wherein the heat shield has end faces formed with a plurality of conductive elements interspaced by an electrically insulating material which provide heat conduction paths at least in part to the cooling area.
- 7. A heat shield for an MRI scanner substantially as hereinbefore described with reference to the drawing.7. A heat shield for an MRI scanner substantially as hereinbefore described with reference to the drawing.Amendments to the Claims have been filed as follows Claims 1. A heat shield for a MRI scanner comprising a plurality of conductive elements embedded within, and interspaced by, an electrically insulating material which conductive elements are aligned to provide heat conduction paths to at least one cooling area, in use, coupled to a cooling source.2. A heat shield as claimed in claim 1 wherein the conductive elements are formed of a metal.3. A heat shield as claimed in claim 2 wherein the metal is copper.4. A heat shield as claimed in any preceding claim wherein a low emissivity layer is applied over the conductive elements and electrically insulating material to Q 15 prevent heat transfer to the shield.O 5. A heat shield as claimed in any preceding claim wherein the conductive C\J elements extend circumferentially about the heat shield.6. A heat shield as claimed in any preceding claim wherein the heat shield has end faces formed with a plurality of conductive elements embedded within, and interspaced by, an electrically insulating material which conductive elements provide heat conduction paths at least in part to the cooling area.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0721799A GB2454475A (en) | 2007-11-07 | 2007-11-07 | A Heat Shield for an MRI scanner |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0721799A GB2454475A (en) | 2007-11-07 | 2007-11-07 | A Heat Shield for an MRI scanner |
Publications (2)
Publication Number | Publication Date |
---|---|
GB0721799D0 GB0721799D0 (en) | 2007-12-19 |
GB2454475A true GB2454475A (en) | 2009-05-13 |
Family
ID=38858250
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB0721799A Withdrawn GB2454475A (en) | 2007-11-07 | 2007-11-07 | A Heat Shield for an MRI scanner |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2454475A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2467596A (en) * | 2009-02-10 | 2010-08-11 | Siemens Magnet Technology Ltd | Thermal radiation shield for a cryostat made from a plastic-metal hybrid |
DE102010008263A1 (en) * | 2010-02-17 | 2011-08-18 | Abmayr, Ute, 89312 | Pressure tank for accommodating e.g. water in sanitary technology, has plastic container designed as injection molding part with layer arranged at interior periphery of container and/or external periphery of container |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1096748A (en) * | 1965-06-25 | 1967-12-29 | Air Liquide | Improvements in or relating to thermal insulating structures |
JPS6213010A (en) * | 1985-07-11 | 1987-01-21 | Toshiba Corp | Superconductive electromagnet |
JPS63187606A (en) * | 1987-01-30 | 1988-08-03 | Fuji Electric Co Ltd | Cryogenic container |
JPH05175045A (en) * | 1991-12-26 | 1993-07-13 | Hitachi Ltd | Super conducting magnet |
GB2435918A (en) * | 2006-03-10 | 2007-09-12 | Siemens Magnet Technology Ltd | Thermal barriers |
-
2007
- 2007-11-07 GB GB0721799A patent/GB2454475A/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1096748A (en) * | 1965-06-25 | 1967-12-29 | Air Liquide | Improvements in or relating to thermal insulating structures |
JPS6213010A (en) * | 1985-07-11 | 1987-01-21 | Toshiba Corp | Superconductive electromagnet |
JPS63187606A (en) * | 1987-01-30 | 1988-08-03 | Fuji Electric Co Ltd | Cryogenic container |
JPH05175045A (en) * | 1991-12-26 | 1993-07-13 | Hitachi Ltd | Super conducting magnet |
GB2435918A (en) * | 2006-03-10 | 2007-09-12 | Siemens Magnet Technology Ltd | Thermal barriers |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2467596A (en) * | 2009-02-10 | 2010-08-11 | Siemens Magnet Technology Ltd | Thermal radiation shield for a cryostat made from a plastic-metal hybrid |
GB2467596B (en) * | 2009-02-10 | 2011-01-12 | Siemens Magnet Technology Ltd | A thermal radiation shield, a cryostat containing a cooled magnet and an MRI system comprising a radiation shield |
DE102010008263A1 (en) * | 2010-02-17 | 2011-08-18 | Abmayr, Ute, 89312 | Pressure tank for accommodating e.g. water in sanitary technology, has plastic container designed as injection molding part with layer arranged at interior periphery of container and/or external periphery of container |
DE102010008263B4 (en) * | 2010-02-17 | 2012-02-16 | Ute Abmayr | Pressure vessel and method for producing a pressure vessel |
Also Published As
Publication number | Publication date |
---|---|
GB0721799D0 (en) | 2007-12-19 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) |
Free format text: REGISTERED BETWEEN 20090507 AND 20090513 |
|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |