1、Designation: F2052 14Standard Test Method forMeasurement of Magnetically Induced Displacement Forceon Medical Devices in the Magnetic ResonanceEnvironment1This standard is issued under the fixed designation F2052; the number immediately following the designation indicates the year oforiginal adoptio
2、n or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the mag-netically induced displa
3、cement force produced by static mag-netic field gradients on medical devices and the comparison ofthat force to the weight of the medical device.1.2 This test method does not address other possible safetyissues which include but are not limited to issues of magneti-cally induced torque, RF heating,
4、induced heating, acousticnoise, interaction among devices, and the functionality of thedevice and the MR system.1.3 This test method is intended for devices that can besuspended from a string. Devices which cannot be suspendedfrom a string are not covered by this test method. The weightof the string
5、 from which the device is suspended during the testmust be less than 1 % of the weight of the tested device.1.4 This test method shall be carried out in a horizontal boreMR system with a static magnetic filed oriented horizontallyand parallel to the MR system bore.1.5 The values stated in SI units a
6、re to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practice
7、s and determine the applica-bility of regulatory requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2F2119 Test Method for Evaluation of MR Image Artifactsfrom Passive ImplantsF2182 Test Method for Measurement of Radio FrequencyInduced Heating On or Near Passive Implants DuringMagne
8、tic Resonance ImagingF2213 Test Method for Measurement of Magnetically In-duced Torque on Medical Devices in the Magnetic Reso-nance EnvironmentF2503 Practice for Marking Medical Devices and OtherItems for Safety in the Magnetic Resonance Environment2.2 Other Standards:3IEC 60601233 Ed. 2.0 Medical
9、Electronic EquipmentPart 2: Particular Requirements for the Safety of MagneticResonance Equipment for Medical DiagnosisISO 13485:2003(E) Medical DevicesQuality Manage-ment SystemsRequirements for Regulatory Purposes,definition 3.7ISO 14971 Medical devices - Application of risk manage-ment to medical
10、 devices3. Terminology3.1 Definitions:3.1.1 diamagnetic material, na material whose relativepermeability is less than unity.3.1.2 ferromagnetic material, na material whose magneticmoments are ordered and parallel producing magnetization inone direction.3.1.3 magnetic field strength (H in A/m), nstre
11、ngth of theapplied magnetic field.3.1.4 magnetic induction or magnetic flux density (B in T),nthat magnetic vector quantity which at any point in amagnetic field is measured either by the mechanical forceexperienced by an element of electric current at the point, or bythe electromotive force induced
12、 in an elementary loop duringany change in flux linkages with the loop at the point. Themagnetic induction is frequently referred to as the magnetic1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of Subcom
13、mitteeF04.15 on Material Test Methods.Current edition approved May 15, 2014. Published August 2014. Originallyapproved in 2000. Last previous edition approved in 2006 as F2052 061. DOI:10.1520/F2052-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Serv
14、ice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 10
15、0 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1field. Bois the static field in a MR system. Plain type indicatesa scalar (for example, B) and bold type indicates a vector (forexample, B).3.1.5 magnetic resonance diagnostic device, na deviceintended for general diag
16、nostic use to present images whichreflect the spatial distribution or magnetic resonance spectra, orboth, which reflect frequency and distribution of nuclei exhib-iting nuclear magnetic resonance. Other physical parametersderived from the images or spectra, or both, may also beproduced.3.1.6 magneti
17、c resonance (MR) environment, nvolumewithin the 0.50 mT (5 gauss (G) line of an MR system, whichincludes the entire three dimensional volume of space sur-rounding the MR scanner. For cases where the 0.50 mT line iscontained within the Faraday shielded volume, the entire roomshall be considered the M
18、R environment.3.1.7 magnetic resonance equipment (MR equipment),nmedical electrical equipment which is intended for in-vivomagnetic resonance examination of a patient. The MR equip-ment comprises all parts in hardware and software from thesupply mains to the display monitor. The MR equipment is aPro
19、grammable Electrical Medical System (PEMS).3.1.8 magnetic resonance system (MR system), nensembleof MR equipment, accessories, including means for display,control, energy supplies, and the MR environment.IEC 606012333.1.9 magnetic resonance examination (MR examination),nprocess of acquiring data by
20、magnetic resonance from apatient.3.1.10 magnetic resonance (MR), nresonant absorption ofelectromagnetic energy by an ensemble of atomic particlessituated in a magnetic field.3.1.11 medical device, nany instrument, apparatus,implement, machine, appliance, implant, in vitro reagent orcalibrator, softw
21、are, material, or other similar or related article,intended by the manufacturer to be used, alone or incombination, for human beings for one or more of the specificpurpose(s) of:(1) diagnosis, prevention, monitoring, treatment, or allevia-tion of disease,(2) diagnosis, monitoring, treatment, allevia
22、tion of, or com-pensation for an injury,(3) investigation, replacement, modification, or support of theanatomy or of a physiological process,(4) supporting or sustaining life,(5) control of conception,(6) disinfection of medical devices, and(7) providing information for medical purposes by means ofi
23、n vitro examination of specimens derived from the hu-man body, and which does not achieve its primary in-tended action in or on the human body bypharmacological, immunological, or metabolic means,but which may be assisted in its function by such means.ISO 134853.1.12 magnetically induced displacemen
24、t force, nforceproduced when a magnetic object is exposed to the spatialgradient of a magnetic field. This force will tend to cause theobject to translate in the gradient field.3.1.13 paramagnetic material, na material having a rela-tive permeability which is slightly greater than unity, andwhich is
25、 practically independent of the magnetizing force.3.1.14 tesla, (T), nthe SI unit of magnetic induction equalto 104gauss (G).4. Summary of Test Method4.1 A medical device is suspended by a string in an MRsystem at a location near the entrance to the bore and on theaxis of the bore. In order to incre
26、ase the measurementsensitivity, this location shall be chosen so that the spatialgradient of the field strength, B = dB/dz, is within 20 percentof the maximum value of the spatial gradient on the axis of thebore. The angular deflection of the string from the vertical ismeasured. If the device deflec
27、ts less than 45, then thedeflection force induced by the MR systems magnetic field isless than the force on the device due to gravity (its weight).NOTE 1It is important to choose a test location on the bore axis withas large a value of B as practical in order to increase the measurementsensitivity.
28、This is particularly important if the test result is used in ananalysis like that in Appendix X3 to determine a maximum allowablespatial gradient to which the device may safely be exposed.5. Significance and Use5.1 This test method is one of those required to determine ifthe presence of a medical de
29、vice may cause injury to individu-als during an MR examination and in the MR environment.Other safety issues which should be addressed include but maynot be limited to magnetically induced torque (see Test MethodF2213) and RF heating (see Test Method F2182). The termsand icons in Practice F2503 shou
30、ld be used to mark the devicefor safety in the magnetic resonance environment.5.2 If the device deflects less than 45, then the magneti-cally induced deflection force is less than the force on thedevice due to gravity (its weight). For this condition, it isassumed that any risk imposed by the applic
31、ation of themagnetically induced force is no greater than any risk imposedby normal daily activity in the Earths gravitational field. Thisstatement does not constitute an acceptance criterion, howeverit is provided for a conservative reference point. It is possiblethat a greater magnetically induced
32、 deflection force can beacceptable and would not harm a patient. For forces greaterthan gravity the location of the implant and means of fixationmust be considered. Magnetically induced deflection forcesgreater than the force of gravity may be acceptable when theycan be justified for the specific ca
33、se.5.3 A deflection of less than 45 at the location of themaximum spatial gradient of the static magnetic field in oneMR system does not preclude a deflection exceeding 45 in asystem with a higher field strength or larger static field spatialgradients.5.4 This test method alone is not sufficient for
34、 determiningif a device is safe in the MR environment.6. Apparatus6.1 The test fixture consists of a sturdy nonmagnetic struc-ture capable of holding the test device in the proper positionwithout deflection of the test fixture and containing a protractorF2052 142with 1 graduated markings, rigidly mo
35、unted to the structure.The 0 indicator on the protractor is oriented vertically. Thetest device is suspended from a thin string that is attached to the0 indicator on the protractor. In order for the weight of thestring to be considered negligible when compared to the weightof the device, the weight
36、of the string shall be less than 1 % ofthe weight of the device. The string shall be long enough sothat the device may be suspended from the test fixture and hangfreely in space. Motion of the string shall not be constrained bythe support structure or the protractor. The string may beattached to the
37、 device at any convenient location.NOTE 2For devices with low mass, it may be appropriate to testmultiple devices simultaneously in order to increase the mass of the testobject.NOTE 3Should the device weight be small to the degree that a supportweighing less than1%ofitsweight is impracticable, a sci
38、entific rationaleshall be applied to the test results in order to determine whether or not theobserved deflection of the device reflects a deflection force in excess of thegravitational force.7. Test Specimens7.1 For purposes of device qualification, the device evalu-ated according to this test meth
39、od should be representative ofmanufactured medical devices that have been processed to afinished condition (for example, sterilized).7.2 For purposes of device qualification, the devices shouldnot be altered in any manner prior to testing.8. Procedure8.1 The test shall be conducted in a horizontal b
40、ore MRsystem with a static magnetic field oriented horizontally andparallel to the bore. Fig. 1 shows the test fixture mounted on thepatient table of an MR system. The test device is suspendedfrom a string attached to the 0 indicator on the test fixtureprotractor. Position the test fixture so that t
41、he center of mass ofthe device is at the test location. The test location is at theentrance of the MR system bore and on the axis of the bore.Atthe test location, the magnetically induced force, Fm,ishorizontal and both B and B act in the z direction. In order toincrease the measurement sensitivity,
42、 this location shall bechosen so that the spatial gradient of the field strength, B =dB/dz, is within 20 percent of the maximum value of the spatialgradient on the axis of the bore. Record the Cartesian coordi-nates (x, y, z) of the test location.Also determine and record thevalues of the field stre
43、ngth, B, and the spatial gradient of thefield strength, B = dB/dz at the test location. Record , thedeflection of the device from the vertical direction to thenearest 1 (see Fig. 2).8.2 Repeat the process in 8.1 a minimum of three times foreach device tested.8.3 The device should be held so that the
44、 bulk of the deviceis at the test location (see Appendix X2). If anything (forexample, tape) is used to hold the device during the test,demonstrate that the added mass does not significantly affectthe measurement. When possible, the combined weight ofmaterial used to hold the device during the test
45、shall be lessthan 1 % of the weight of the device. If the weight of theholding material exceeds 1 % of the weight of the device,report the weight of the holding material.NOTE 4In particular, nonrigid, or multi-component devices (forexample, a pacemaker lead) need to be held (for example, bundled) so
46、 thatthe bulk of the device is at the test location.8.4 If the device contains an electrical cord or some type oftether, arrange the device so the cord or tether has a minimaleffect on the measurement. For such devices, it may benecessary to perform a series of tests to characterize theoperating con
47、ditions that will produce the maximum deflec-tion. (For instance, for an electrically powered device, tests ina number of states may be necessary to determine the operatingcondition that produces the maximum deflection. Possible testconfigurations include but are not limited to: electrical cordonly,
48、 device only, device with cord attached and device turnedoff, device with cord attached and device activated).NOTE 5At the test location, the magnetically induced force, Fm,ishorizontal and both B and =B act only in the z direction.NOTE 6For paramagnetic materials (for example, nitinol, CoCrMoalloys
49、, titanium and its alloys, 316L stainless steel) and for unsaturatedferromagnetic material, the magnetically induced deflection force isproportional to the product of the static magnetic field and the spatialgradient of the static magnetic field. For devices composed of thesematerials, the location of maximum deflection is at the point where |B|=B| is a maximum. For saturated ferromagnetic materials, the maximumdeflection will occur at the location where =B is a maximum.9. Calculations9.1 Calculate the mean deflection angle using the a
