1、Designation: F2052 14F2052 15Standard 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
2、 adoption 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 magnetically induced
3、 displacement force produced by static magnetic fieldgradients on medical devices and the comparison of that force to the weight of the medical device.1.2 This test method does not address other possible safety issues which include but are not limited to issues of magneticallyinduced torque, RF heat
4、ing, induced heating, acoustic noise, interaction among devices, and the functionality of the device and theMR system.1.3 This test method is intended for devices that can be suspended from a string. Devices which cannot be suspended from astring are not covered by this test method. The weight of th
5、e string from which the device is suspended during the test must beless than 1 % of the weight of the tested device.1.4 This test method shall be carried out in a horizontal bore MR system with a static magnetic filed oriented horizontally andparallel to the MR system bore.1.5 The values stated in S
6、I units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and heal
7、th practices and determine the applicability of regulatoryrequirements prior to use.2. Referenced Documents2.1 ASTM Standards:2F2119 Test Method for Evaluation of MR Image Artifacts from Passive ImplantsF2182 Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants
8、During MagneticResonance ImagingF2213 Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic ResonanceEnvironmentF2503 Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment2.2 Other Standards:3IEC 60601233 Ed. 2.0
9、 Medical Electronic EquipmentPart 2: Particular Requirements for the Safety of Magnetic ResonanceEquipment for Medical DiagnosisISO 13485:2003(E) Medical DevicesQuality Management SystemsRequirements for Regulatory Purposes, definition 3.7ISO 14971 Medical devices - Application of risk management to
10、 medical devices3. Terminology3.1 Definitions:3.1.1 diamagnetic material, na material whose relative permeability is less than unity.1 This test method is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15
11、 on Material Test Methods.Current edition approved May 15, 2014Sept. 15, 2015. Published August 2014September 2015. Originally approved in 2000. Last previous edition approved in 20062014as F2052 06F2052 14.1. DOI: 10.1520/F2052-14.10.1520/F2052-15.2 For referencedASTM standards, visit theASTM websi
12、te, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, ht
13、tp:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users
14、consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.2 ferromagnetic material, n
15、a material whose magnetic moments are ordered and parallel producing magnetization in onedirection.3.1.3 magnetic field strength (H in A/m), nstrength of the applied magnetic field.3.1.4 magnetic induction or magnetic flux density (B in T), nthat magnetic vector quantity which at any point in a magn
16、eticfield is measured either by the mechanical force experienced by an element of electric current at the point, or by the electromotiveforce induced in an elementary loop during any change in flux linkages with the loop at the point. The magnetic induction isfrequently referred to as the magnetic f
17、ield. Bo is the static field in a MR system. Plain type indicates a scalar (for example, B)and bold type indicates a vector (for example, B).3.1.5 magnetic resonance diagnostic device, na device intended for general diagnostic use to present images which reflect thespatial distribution or magnetic r
18、esonance spectra, or both, which reflect frequency and distribution of nuclei exhibiting nuclearmagnetic resonance. Other physical parameters derived from the images or spectra, or both, may also be produced.3.1.6 magnetic resonance (MR) environment, nvolume within the 0.50 mT(5 gauss (G) line of an
19、 MR system, which includesthe entire three dimensional volume of space surrounding the MR scanner. For cases where the 0.50 mT line is contained withinthe Faraday shielded volume, the entire room shall be considered the MR environment.3.1.7 magnetic resonance equipment (MR equipment), nmedical elect
20、rical equipment which is intended for in-vivo magneticresonance examination of a patient. The MR equipment comprises all parts in hardware and software from the supply mains tothe display monitor. The MR equipment is a Programmable Electrical Medical System (PEMS).3.1.8 magnetic resonance system (MR
21、 system), nensemble of 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 magnetic resonance from a patient.3.1.10 magnetic resonance (MR), nresonant
22、absorption of electromagnetic energy by an ensemble of atomic particles situatedin a magnetic field.3.1.11 medical device, nany instrument, apparatus, implement, machine, appliance, implant, in vitro reagent or calibrator,software, material, or other similar or related article, intended by the manuf
23、acturer to be used, alone or in combination, for humanbeings for one or more of the specific purpose(s) of:(1) diagnosis, prevention, monitoring, treatment, or allevia-tion of disease,(2) diagnosis, monitoring, treatment, alleviation of, or com-pensation for an injury,(3) investigation, replacement,
24、 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 ofin vitro examination of specimens derived from the hu-man body, and whic
25、h 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 displacement force, nforce produced when a magnetic object is exposed to the spati
26、al gradientof a magnetic field. This force will tend to cause the object to translate in the gradient field.3.1.13 paramagnetic material, na material having a relative permeability which is slightly greater than unity, and which ispractically independent of the magnetizing force.3.1.14 tesla, (T), n
27、the SI unit of magnetic induction equal to 104 gauss (G).4. Summary of Test Method4.1 A medical device is suspended by a string in an MR system at a location near the entrance to the bore and on the axis ofthe bore. In order to increase the measurement sensitivity, this location shall be chosen so t
28、hat the spatial gradient of the fieldstrength, piB = dB/dz, is within 20 percent of the maximum value of the spatial gradient on the axis of the bore. The angulardeflection of the string from the vertical is measured. If the device deflects less than 45, then the deflection force induced by theMR sy
29、stems magnetic field is less than the force on the device due to gravity (its weight).NOTE 1It is important to choose a test location on the bore axis with as large a value of piB as practical in order to increase the measurementsensitivity. This is particularly important if the test result is used
30、in an analysis like that in Appendix X3 to determine a maximum allowable spatialgradient to which the device may safely be exposed.5. Significance and Use5.1 This test method is one of those required to determine if the presence of a medical device may cause injury to individualsduring an MR examina
31、tion and in the MR environment. Other safety issues which should be addressed include but may not beF2052 152limited to magnetically induced torque (see Test Method F2213) and RF heating (see Test Method F2182). The terms and iconsin Practice F2503 should be used to mark the device for safety in the
32、 magnetic resonance environment.5.2 If the device deflects less than 45, then the magnetically induced deflection force is less than the force on the device dueto gravity (its weight). For this condition, it is assumed that any risk imposed by the application of the magnetically induced forceis no g
33、reater than any risk imposed by normal daily activity in the Earths gravitational field. This statement does not constitutean acceptance criterion, however it is provided for a conservative reference point. It is possible that a greater magnetically induceddeflection force can be acceptable and woul
34、d not harm a patient. For forces greater than gravity the location of the implant andmeans of fixation must be considered. Magnetically induced deflection forces greater than the force of gravity may be acceptablewhen they can be justified for the specific case.5.3 A deflection of less than 45 at th
35、e location of the maximum spatial gradient of the static magnetic field in one MR systemdoes not preclude a deflection exceeding 45 in a system with a higher field strength or larger static field spatial gradients.5.4 This test method alone is not sufficient for determining if a device is safe in th
36、e MR environment.6. Apparatus6.1 The test fixture consists of a sturdy nonmagnetic structure capable of holding the test device in the proper position withoutdeflection of the test fixture and containing a protractor with 1 graduated markings, rigidly mounted to the structure. The 0indicator on the
37、protractor is oriented vertically. The test device is suspended from a thin string that is attached to the 0 indicatoron the protractor. In order for the weight of the string to be considered negligible when compared to the weight of the device, theweight of the string shall be less than 1 % of the
38、weight of the device. The string shall be long enough so that the device may besuspended from the test fixture and hang freely in space. Motion of the string shall not be constrained by the support structure orthe protractor. The string may be attached to the device at any convenient location.NOTE 2
39、For devices with low mass, it may be appropriate to test multiple devices simultaneously in order to increase the mass of the test object.NOTE 3Should the device weight be small to the degree that a support weighing less than 1 % of its weight is impracticable, a scientific rationaleshall be applied
40、 to the test results in order to determine whether or not the observed deflection of the device reflects a deflection force in excess of thegravitational force.7. Test Specimens7.1 For purposes of device qualification, the device evaluated according to this test method should be representative ofman
41、ufactured medical devices that have been processed to a finished condition (for example, sterilized).7.2 For purposes of device qualification, the devices should not be altered in any manner prior to testing.8. Procedure8.1 The test shall be conducted in a horizontal bore MR system with a static mag
42、netic field oriented horizontally and parallelto the bore. Fig. 1 shows the test fixture mounted on the patient table of an MR system. The test device is suspended from a stringattached to the 0 indicator on the test fixture protractor. Position the test fixture so that the center of mass of the dev
43、ice is at thetest location. The test location is at the entrance of the MR system bore and on the axis of the bore. At the test location, themagnetically induced force, Fm, is horizontal and both B and piB act in the z direction. In order to increase the measurementsensitivity, this location shall b
44、e chosen so that the spatial gradient of the field strength, piB = dB/dz, is within 20 percent of themaximum value of the spatial gradient on the axis of the bore. Record the Cartesian coordinates (x, y, z) of the test location. Alsodetermine and record the values of the field strength, B, and the s
45、patial gradient of the field strength, piB = dB/dz at the testlocation. Record , the deflection of the device from the vertical direction to the nearest 1 (see Fig. 2).8.2 Repeat the process in 8.1 a minimum of three times for each device tested.8.3 The device should be held so that the bulk of the
46、device is at the test location (see Appendix X2). If anything (for example,tape) is used to hold the device during the test, demonstrate that the added mass does not significantly affect the measurement.FIG. 1 Test Fixture Mounted on the Patient Table of aMRI SystemF2052 153When possible, the combin
47、ed weight of material used to hold the device during the test shall be less than 1 % of the weight ofthe device. If the weight of the holding material exceeds 1 % of the weight of the device, report the weight of the holding material.NOTE 4In particular, nonrigid, or multi-component devices (for exa
48、mple, a pacemaker lead) need to be held (for example, bundled) so that the bulkof the device is at the test location.8.4 If the device contains an electrical cord or some type of tether, arrange the device so the cord or tether has a minimal effecton the measurement. For such devices, it may be nece
49、ssary to perform a series of tests to characterize the operating conditions thatwill produce the maximum deflection. (For instance, for an electrically powered device, tests in a number of states may benecessary to determine the operating condition that produces the maximum deflection. Possible test configurations include but arenot limited to: electrical cord only, device only, device with cord attached and device turned off, device with cord attached anddevice activated).NOTE 5At the test location, the magnetically induced force, Fm,
