ASTM F2213-17
(Test Method)Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment
Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment
SIGNIFICANCE AND USE
5.1 This test method is one of those required to determine if the presence of a medical device may cause injury in the magnetic resonance environment. Other safety issues which should be addressed include but may not be limited to magnetically induced force (see Test Method F2052), RF heating (see Test Method F2182), and image artifact (see Test Method F2119). ISO TS 10974 addresses hazards produced by active implantable medical devices in the MR Environment.
5.2 The terms MR Conditional, MR Safe, and MR Unsafe together with the corresponding icons in Practice F2503 shall be used to mark the device for safety in the MR environment.
5.3 The acceptance criterion associated with this test shall be justified. If the maximum magnetically induced torque is less than the product of the longest dimension of the medical device and its weight, then the magnetically induced torque is less than the worst case torque on the device due to gravity. For this condition, it is assumed that any risk imposed by the application of the magnetically induced torque is no greater than any risk imposed by normal daily activity in the Earth's gravitational field. This is conservative. It is possible that greater torques also would not pose a hazard. (For example, device position with respect to adjacent tissue, tissue ingrowth, or other mechanisms may act to prevent device movement or forces produced by a magnetically induced torque that are greater than the torque due to gravity from causing harm to adjacent tissue.)
5.4 This test method alone is not sufficient for determining if an implant is safe in the MR environment.
5.5 The magnetically induced torque considered in this standard is the magneto-static torque due to the interaction of the MRI static magnetic field with the magnetization in the implant. The dynamic torque due to interaction of the static field with eddy currents induced in a rotating device is not addressed in this test method. Currents in lead wires may induce...
SCOPE
1.1 This test method covers the measurement of the magnetically induced torque produced by the static magnetic field in the magnetic resonance environment on medical devices and the comparison of that torque a user-specified acceptance criterion.
1.2 This test method does not address other possible safety issues which may include, but are not limited to, magnetically induced deflection force, tissue heating, device malfunction, imaging artifacts, acoustic noise, interaction among devices, and the functionality of the device and the MR system.
1.3 The torque considered here is the magneto-static torque due to the interaction of the MRI static magnetic field with the magnetization of the implant. The dynamic torque due to interaction of the static field with eddy currents induced in a rotating device is not addressed in this test method. Torque induced by currents in lead wires is not addressed by this standard.
1.4 The methods in this standard are applicable for MR systems with a horizontal magnetic field. Not all of the methods described in this standard are applicable for use in an MR system with a vertical magnetic field. The Suspension Method and the Low Friction Surface Method require gravity to be orthogonal to the magnetically induced torsion and may not be performed using a vertical magnetic field. The Torsional Spring and Pulley Methods can be adapted to work in a vertical magnetic field, however the example apparatus are not appropriate for use in a vertical magnetic field. The Calculation Based on Measured Displacement Force Method is independent of the MR system and thus could be used for an MR system with a vertical magnetic field.
1.5 The values stated in SI 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 responsibility of the u...
General Information
- Status
- Published
- Publication Date
- 31-Aug-2017
- Technical Committee
- F04 - Medical and Surgical Materials and Devices
- Drafting Committee
- F04.15 - Material Test Methods
- Current Stage
Relations
- Effective Date
- 01-Sep-2017
- Effective Date
- 01-Apr-2023
- Effective Date
- 15-Sep-2019
- Effective Date
- 15-Sep-2019
- Effective Date
- 15-May-2014
- Effective Date
- 01-Jun-2013
- Effective Date
- 15-Apr-2011
- Effective Date
- 01-Mar-2011
- Effective Date
- 15-Nov-2009
- Effective Date
- 01-Oct-2008
- Refers
ASTM F2119-07 - Standard Test Method for Evaluation of MR Image Artifacts from Passive Implants - Effective Date
- 01-Sep-2007
- Effective Date
- 01-Mar-2006
- Effective Date
- 01-Mar-2006
- Effective Date
- 01-Aug-2005
- Effective Date
- 10-Nov-2002
ASTM F2213-17 - Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment
REDLINE ASTM F2213-17 - Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment
Frequently Asked Questions
ASTM F2213-17 is a standard published by ASTM International. Its full title is "Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment". This standard covers: SIGNIFICANCE AND USE 5.1 This test method is one of those required to determine if the presence of a medical device may cause injury in the magnetic resonance environment. Other safety issues which should be addressed include but may not be limited to magnetically induced force (see Test Method F2052), RF heating (see Test Method F2182), and image artifact (see Test Method F2119). ISO TS 10974 addresses hazards produced by active implantable medical devices in the MR Environment. 5.2 The terms MR Conditional, MR Safe, and MR Unsafe together with the corresponding icons in Practice F2503 shall be used to mark the device for safety in the MR environment. 5.3 The acceptance criterion associated with this test shall be justified. If the maximum magnetically induced torque is less than the product of the longest dimension of the medical device and its weight, then the magnetically induced torque is less than the worst case torque on the device due to gravity. For this condition, it is assumed that any risk imposed by the application of the magnetically induced torque is no greater than any risk imposed by normal daily activity in the Earth's gravitational field. This is conservative. It is possible that greater torques also would not pose a hazard. (For example, device position with respect to adjacent tissue, tissue ingrowth, or other mechanisms may act to prevent device movement or forces produced by a magnetically induced torque that are greater than the torque due to gravity from causing harm to adjacent tissue.) 5.4 This test method alone is not sufficient for determining if an implant is safe in the MR environment. 5.5 The magnetically induced torque considered in this standard is the magneto-static torque due to the interaction of the MRI static magnetic field with the magnetization in the implant. The dynamic torque due to interaction of the static field with eddy currents induced in a rotating device is not addressed in this test method. Currents in lead wires may induce... SCOPE 1.1 This test method covers the measurement of the magnetically induced torque produced by the static magnetic field in the magnetic resonance environment on medical devices and the comparison of that torque a user-specified acceptance criterion. 1.2 This test method does not address other possible safety issues which may include, but are not limited to, magnetically induced deflection force, tissue heating, device malfunction, imaging artifacts, acoustic noise, interaction among devices, and the functionality of the device and the MR system. 1.3 The torque considered here is the magneto-static torque due to the interaction of the MRI static magnetic field with the magnetization of the implant. The dynamic torque due to interaction of the static field with eddy currents induced in a rotating device is not addressed in this test method. Torque induced by currents in lead wires is not addressed by this standard. 1.4 The methods in this standard are applicable for MR systems with a horizontal magnetic field. Not all of the methods described in this standard are applicable for use in an MR system with a vertical magnetic field. The Suspension Method and the Low Friction Surface Method require gravity to be orthogonal to the magnetically induced torsion and may not be performed using a vertical magnetic field. The Torsional Spring and Pulley Methods can be adapted to work in a vertical magnetic field, however the example apparatus are not appropriate for use in a vertical magnetic field. The Calculation Based on Measured Displacement Force Method is independent of the MR system and thus could be used for an MR system with a vertical magnetic field. 1.5 The values stated in SI 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 responsibility of the u...
SIGNIFICANCE AND USE 5.1 This test method is one of those required to determine if the presence of a medical device may cause injury in the magnetic resonance environment. Other safety issues which should be addressed include but may not be limited to magnetically induced force (see Test Method F2052), RF heating (see Test Method F2182), and image artifact (see Test Method F2119). ISO TS 10974 addresses hazards produced by active implantable medical devices in the MR Environment. 5.2 The terms MR Conditional, MR Safe, and MR Unsafe together with the corresponding icons in Practice F2503 shall be used to mark the device for safety in the MR environment. 5.3 The acceptance criterion associated with this test shall be justified. If the maximum magnetically induced torque is less than the product of the longest dimension of the medical device and its weight, then the magnetically induced torque is less than the worst case torque on the device due to gravity. For this condition, it is assumed that any risk imposed by the application of the magnetically induced torque is no greater than any risk imposed by normal daily activity in the Earth's gravitational field. This is conservative. It is possible that greater torques also would not pose a hazard. (For example, device position with respect to adjacent tissue, tissue ingrowth, or other mechanisms may act to prevent device movement or forces produced by a magnetically induced torque that are greater than the torque due to gravity from causing harm to adjacent tissue.) 5.4 This test method alone is not sufficient for determining if an implant is safe in the MR environment. 5.5 The magnetically induced torque considered in this standard is the magneto-static torque due to the interaction of the MRI static magnetic field with the magnetization in the implant. The dynamic torque due to interaction of the static field with eddy currents induced in a rotating device is not addressed in this test method. Currents in lead wires may induce... SCOPE 1.1 This test method covers the measurement of the magnetically induced torque produced by the static magnetic field in the magnetic resonance environment on medical devices and the comparison of that torque a user-specified acceptance criterion. 1.2 This test method does not address other possible safety issues which may include, but are not limited to, magnetically induced deflection force, tissue heating, device malfunction, imaging artifacts, acoustic noise, interaction among devices, and the functionality of the device and the MR system. 1.3 The torque considered here is the magneto-static torque due to the interaction of the MRI static magnetic field with the magnetization of the implant. The dynamic torque due to interaction of the static field with eddy currents induced in a rotating device is not addressed in this test method. Torque induced by currents in lead wires is not addressed by this standard. 1.4 The methods in this standard are applicable for MR systems with a horizontal magnetic field. Not all of the methods described in this standard are applicable for use in an MR system with a vertical magnetic field. The Suspension Method and the Low Friction Surface Method require gravity to be orthogonal to the magnetically induced torsion and may not be performed using a vertical magnetic field. The Torsional Spring and Pulley Methods can be adapted to work in a vertical magnetic field, however the example apparatus are not appropriate for use in a vertical magnetic field. The Calculation Based on Measured Displacement Force Method is independent of the MR system and thus could be used for an MR system with a vertical magnetic field. 1.5 The values stated in SI 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 responsibility of the u...
ASTM F2213-17 is classified under the following ICS (International Classification for Standards) categories: 17.220.20 - Measurement of electrical and magnetic quantities. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM F2213-17 has the following relationships with other standards: It is inter standard links to ASTM F2213-06(2011), ASTM F2503-23e1, ASTM F2182-19e1, ASTM F2182-19, ASTM F2052-14, ASTM F2503-13, ASTM F2182-11a, ASTM F2182-11, ASTM F2182-09, ASTM F2503-08, ASTM F2119-07, ASTM F2052-06, ASTM F2052-06e1, ASTM F2503-05, ASTM F2182-02a. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F2213 − 17
Standard Test Method for
Measurement of Magnetically Induced Torque on Medical
Devices in the Magnetic Resonance Environment
This standard is issued under the fixed designation F2213; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the measurement of the mag-
responsibility of the user of this standard to establish appro-
netically induced torque produced by the static magnetic field
priate safety, health, and environmental practices and deter-
inthemagneticresonanceenvironmentonmedicaldevicesand
mine the applicability of regulatory limitations prior to use.
the comparison of that torque a user-specified acceptance
1.7 This international standard was developed in accor-
criterion.
dance with internationally recognized principles on standard-
1.2 This test method does not address other possible safety
ization established in the Decision on Principles for the
issues which may include, but are not limited to, magnetically
Development of International Standards, Guides and Recom-
induced deflection force, tissue heating, device malfunction,
mendations issued by the World Trade Organization Technical
imaging artifacts, acoustic noise, interaction among devices,
Barriers to Trade (TBT) Committee.
and the functionality of the device and the MR system.
1.3 The torque considered here is the magneto-static torque
2. Referenced Documents
due to the interaction of the MRI static magnetic field with the
2.1 ASTM Standards:
magnetization of the implant. The dynamic torque due to
F2052Test Method for Measurement of Magnetically In-
interaction of the static field with eddy currents induced in a
duced Displacement Force on Medical Devices in the
rotating device is not addressed in this test method. Torque
Magnetic Resonance Environment
induced by currents in lead wires is not addressed by this
F2119Test Method for Evaluation of MR Image Artifacts
standard.
from Passive Implants
1.4 The methods in this standard are applicable for MR
F2182Test Method for Measurement of Radio Frequency
systems with a horizontal magnetic field. Not all of the
Induced Heating On or Near Passive Implants During
methods described in this standard are applicable for use in an
Magnetic Resonance Imaging
MR system with a vertical magnetic field. The Suspension
F2503Practice for Marking Medical Devices and Other
Method and the Low Friction Surface Method require gravity
Items for Safety in the Magnetic Resonance Environment
to be orthogonal to the magnetically induced torsion and may
2.2 Other Standards:
notbeperformedusingaverticalmagneticfield.TheTorsional
IEC 60601-2-33Medical electrical equipment - Part 2-33:
SpringandPulleyMethodscanbeadaptedtoworkinavertical
Particular requirements for the basic safety and essential
magnetic field, however the example apparatus are not appro-
performance of magnetic resonance equipment for medi-
priate for use in a vertical magnetic field. The Calculation
cal diagnosis
Based on Measured Displacement Force Method is indepen-
ISO 13485Medical devices -- Quality management systems
dent of the MR system and thus could be used for an MR
-- Requirements for regulatory purposes
system with a vertical magnetic field.
ISO TS 10974Assessment of the safety of magnetic reso-
1.5 The values stated in SI units are to be regarded as
nance imaging for patients with an active implantable
standard. No other units of measurement are included in this
medical device
standard.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ThistestmethodisunderthejurisdictionofASTMCommitteeF04onMedical contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
andSurgicalMaterialsandDevicesandisthedirectresponsibilityofSubcommittee Standards volume information, refer to the standard’s Document Summary page on
F04.15 on Material Test Methods. the ASTM website.
Current edition approved Sept. 1, 2017. Published October 2017. Originally Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
approved in 2002. Last previous edition approved in 2011 as F2213–06(2011). 4th Floor, New York, NY 10036, http://www.ansi.org.
DOI: 10.1520/F2213-17. Specifically, definition 3.11.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2213 − 17
3. Terminology intended by the manufacturer to be used, alone or in
combination, for human beings for one or more of the specific
3.1 Definitions:
purpose(s) of:
3.1.1 diamagnetic material, n—a material whose relative
(1) diagnosis, prevention, monitoring, treatment, or alleviation of disease;
permeability is less than unity.
(2) diagnosis, monitoring, treatment, alleviation of, or compensation for an
injury;
3.1.2 ferromagnetic material, n—amaterialwhosemagnetic
(3) investigation, replacement, modification, or support of the anatomy or of
moments are ordered and parallel producing magnetization in
a physiological process;
one direction.
(4) supporting or sustaining life;
(5) control of conception;
3.1.3 magnetic induction or magnetic flux density (B in T),
(6) disinfection of medical devices; and
n—that magnetic vector quantity which at any point in a
(7) providing information for medical purposes by means of in vitro exami-
nation of specimens derived from the human body, and which does not
magnetic field is measured either by the mechanical force
achieve its primary intended action in or on the human body by
experiencedbyanelementofelectriccurrentatthepoint,orby
pharmacological, immunological, or metabolic means, but which may be
the electromotive force induced in an elementary loop during
assisted in its function by such means.
ISO 13485
any change in flux linkages with the loop at the point. The
magnetic induction is frequently referred to as the magnetic
3.1.14 paramagnetic material, n—a material having a rela-
field. B isthestaticfieldinanMRsystem.Plaintypeindicates
0 tive permeability which is slightly greater than unity, and
a scalar (for example, B) and bold type indicates a vector (for
which is practically independent of the magnetizing force.
example,B).
3.1.15 passive implant, n—an implant that serves its func-
3.1.4 magnetic field strength (H in A/m), n—strength of the
tion without the supply of electrical power.
applied magnetic field.
3.1.16 tesla, (T), n—the SI unit of magnetic induction equal
3.1.5 magnetic resonance (MR), n—resonant absorption of
to 10 gauss (G).
electromagnetic energy by an ensemble of atomic particle
4. Summary of Test Method
situated in a magnetic field.
4.1 The static magnetic field associated with an MR system
3.1.6 magnetic resonance (MR) environment, n—volume
within the 0.50 mT(5 gauss (G)) line of an MR system, which producesatorqueonadevicethatactstoalignthelongaxisof
includes the entire three-dimensional volume of space sur- the object with the direction of the magnetic field. Five
rounding the MR scanner. For cases where the 0.50 mT line is methods for measurement or assessment of magnetically in-
contained within the Faraday shielded volume, the entire room duced torque are given in this standard: the Suspension
shall be considered the MR environment. Method, the Low Friction Surface Method, the Torsional
Spring Method, the Pulley Method, and the Calculation Based
3.1.7 magnetic resonance equipment, n—medical electrical
on Measured Displacement Force Method.
equipment which is intended for magnetic resonance examina-
tion of a patient. The MR equipment comprises all parts in 4.2 The Suspension Method and the Low Friction Surface
hardware and software from the supply mains to the display
Method are not appropriate for devices for which the magneti-
monitor. The MR equipment is a Programmable Electrical cally induced torque is expected to be greater than the torque
Medical System (PEMS). IEC 60601-2-33
due to gravity.
3.1.8 magnetic resonance imaging (MRI), n—imaging tech-
4.3 The Low Friction Surface Method is performed by
nique that uses static and time-varying magnetic fields to
placing the device on a low friction non-metallic, non-
provide images of tissue by the magnetic resonance of nuclei.
conductive surface as near as practical to the isocenter of the
MR system. The device is then rotated in defined angular
3.1.9 magnetic resonance system (MR System),
increments while alignment or rotation of the device with the
n—ensemble of MR equipment, accessories including means
staticmagneticfieldisobserved.Ifrotationofthedeviceisnot
for display, control, energy supplies, and the MR environment.
observed, an upper bound on the magnetically induced torque
IEC 60601-2-33
is estimated using the coefficient of friction between the
3.1.10 magnetically induced displacement force, n—force
surface and the device and the weight of the device. If
produced when a magnetic object is exposed to the spatial
alignment or rotation of the device is observed, then either the
gradient of a magnetic field. This force will tend to cause the
Torsional Spring Method or the Pulley Method shall be
object to translate in the gradient field.
performed. The coefficient of friction is calculated from the
3.1.11 magnetically induced torque, n—torque produced
device weight and the angle of repose (the angle in which the
when a magnetic object is exposed to a magnetic field. This
implant is on the verge of sliding off the low friction surface)
torque will tend to cause the object to align itself along the
which is measured outside the MR environment.
magnetic field in an equilibrium direction that induces no
4.4 TheTorsionSpringMethoddeterminesthemagnetically
torque.
inducedtorqueusingatorsionpendulum.Adeviceisplacedon
3.1.12 magnetization (M in T), n—magnetic moment per
aholdersuspendedbyatorsionspring.Theapparatusisplaced
unit volume
in the center of the magnetic resonance equipment magnet
3.1.13 medical device, n—any instrument, apparatus, where the magnetic field is uniform. The torque is determined
implement, machine, appliance, implant, in vitro reagent or from the measurement of the deflection angle of the holder
calibrator,software,material,orothersimilarorrelatedarticle, fromitsequilibriumposition.Theframeholdingthespringand
F2213 − 17
holderassemblyisrotatedandthetorqueasafunctionofangle devicepositionwithrespecttoadjacenttissue,tissueingrowth,
of the implant is determined. The maximal magnetic torque is or other mechanisms may act to prevent device movement or
compared to the worst case gravitational torque, defined as the forces produced by a magnetically induced torque that are
productofthemaximumlineardimensionofthedeviceandthe greater than the torque due to gravity from causing harm to
device weight. adjacent tissue.)
4.5 The Pulley Method allows determination of the maxi- 5.4 This test method alone is not sufficient for determining
mum magnetically induced torque of the device using a low if an implant is safe in the MR environment.
friction pulley attached to a rotating platform. The device is
5.5 The magnetically induced torque considered in this
fixed on the platform while positioning the device to be
standard is the magneto-static torque due to the interaction of
centered as near as practical to isocenter of the MR system.
the MRI static magnetic field with the magnetization in the
Using a lightweight string attached to the pulley and a force
implant. The dynamic torque due to interaction of the static
gauge, the platform is rotated by pulling the force gauge in a
field with eddy currents induced in a rotating device is not
direct line away from the torque fixture. The maximum torque
addressed in this test method. Currents in lead wires may
is determined by using the maximum reading from the force
induce a torque as well.
gauge.
4.6 The Suspension Method is a qualitative method that is
6. Test Specimens
performed by suspending the device by a lightweight string in
6.1 For purposes of device qualification, the device evalu-
a location as near as practical to the isocenter of the MR
ated according to this test method should be representative of
system. The device is then rotated in defined angular incre-
manufactured devices. The device should be sterilized, unless
ments while movement or rotation of the device to align with
sterilization is not expected to affect the relevant properties of
thestaticmagneticfieldisobserved.Ifrotationofthedeviceis
the device (for example: magnetic susceptibility, weight)
not observed, the magnetically induced torque is small and no
6.2 Forpurposesofdevicequalification,anyalterationfrom
further evaluation is required. If rotation of the device is
the finished condition should be reported. For instance, if
observed,thentheLowFrictionSurfaceMethod,theTorsional
sections are removed from the device for testing or if the
Spring Method, or the Pulley Method shall be performed.
device has not been sterilized, this should be reported.
4.7 The Calculation Based on Measured Displacement
Force Method provides an upper bound for the magnetically
7. Procedure
induced torque based on magnetically induced displacement
7.1 Selection of Test Device:
force measurements using Test Method F2052. This method is
most appropriate for devices which are composed of only one 7.1.1 The test sample shall be worst case for the device
under test. Provide a rationale for the selection of the test
material; however it may also be used with devices composed
of multiple materials (see 7.8.2.2). This method is not appro- sample as worst case. For instance, for devices that are
available in multiple sizes and/or configurations, provide a
priate for devices that contain magnets or ferromagnetic
material. rationale supporting the chosen test sample as worst case for
the entire range of device sizes and/or configurations.
5. Significance and Use
7.1.1.1 It might be appropriate to test only a relevant
sectionofadevice(forexample,foraflexibledevicewithonly
5.1 Thistestmethodisoneofthoserequiredtodetermineif
a small metallic portion, test only the metallic portion of the
the presence of a medical device may cause injury in the
device). A justification for the selected portion of the device
magnetic resonance environment. Other safety issues which
shall be provided. Mass, linear dimension, and material mag-
should be addressed include but may not be limited to
netic susceptibility shall be considered. The worst case com-
magnetically induced force (see Test Method F2052), RF
bination will likely include components with the greatest
heating (see Test Method F2182), and image artifact (see Test
product of the implant mass and the maximum linear dimen-
Method F2119). ISOTS 10974 addresses hazards produced by
sion when compared to other product combinations.
active implantable medical devices in the MR Environment.
5.2 The terms MR Conditional, MR Safe, and MR Unsafe 7.2 Test Device Orientation:
7.2.1 Thetestdeviceshallbetestedwitheachprincipalaxis
together with the corresponding icons in Practice F2503 shall
be used to mark the device for safety in the MR environment. of the test device oriented parallel to the MR system’s static
magnetic field, unless a rationale for a specific worst case
5.3 The acceptance criterion associated with this test shall
orientation is determined. Such a rationale may include con-
be justified. If the maximum magnetically induced torque is
sideration of the clinically possible orientations of the test
less than the product of the longest dimension of the medical
device in relation to B . Note, it is possible for the worst case
device and its weight, then the magnetically induced torque is
orientationtobewiththeprincipalaxesofthetestdeviceatan
lessthantheworstcasetorqueonthedeviceduetogravity.For
oblique(s) angle with respect to B .Also, lead wires should be
this condition, it is assumed that any risk imposed by the
arranged in a manner that is worst case or representative of the
application of the magnetically induced torque is no greater
in vivo configuration. If applicable, the effect of current in lead
than any risk imposed by normal daily activity in the Earth’s
wires should be considered.
gravitational field. This is conservative. It is possible that
greater torques also would not pose a hazard. (For example, 7.3 Coordinate System:
F2213 − 17
7.3.1 Use a right handed Cartesian coordinate system with
origin(x=y=z=0)attheisocenteroftheMRsystem.The z-axis
is parallel to the MR system bore with the positive direction
pointing from the patient table into the bore. The y-axis is
vertical with the positive direction up.
7.4 The Low Friction Surface Method:
7.4.1 The Low Friction Surface Method apparatus consists FIG. 2 Diagram of Angle of Repose (ϴ) Measurement Method
of a low friction non-metallic, non-conductive surface as
shown in Fig. 1.
defined in Eq 2 and which may be calculated from the device
7.4.2 Determination of Coeffıcient of Friction Between the
length, weight, and coefficient of friction determined in 7.4.2.
Implant and the Low Friction Surface:
τ ,LF (2)
magnetic f
7.4.2.1 Perform this process outside the MR environment
where the earth’s magnetic field is the only magnetic field where:
acting on the device.
τ = magnetically induced torque,
magnetic
7.4.2.2 Placethetestdeviceonthesurface(anacrylicsheet,
L = longest dimension of the test device, and
for example). If the device has sides with varied friction
F = friction force between the test device and the low
f
characteristics, use the side with lower friction. Fix one end of
friction surface.
the low friction surface so that it will not slide when the other
The friction force, F, between the test device and the low
f
end is lifted.
friction surface is given in Eq 3.
7.4.2.3 Slowly raise the surface until it reaches the angle of
F 5µmg (3)
f
repose(theangleatwhichthedeviceisonthevergeofsliding)
as shown in Fig. 2. This will require raising the device to an
where:
angleatwhichthetestdevicedoesslideandthenrepeatingthe
F = friction force between the test device and the low
f
processtodeterminetheangleofrepose.Makesurethedevice
friction surface,
slides and does not roll.
µ = coefficient of friction between the test device and the
7.4.2.4 Calculate the coefficient of friction (µ) using Eq 1.
low friction surface (determined in 7.4.2),
m = mass of the device, and
µ 5 tanθ (1)
s
g = acceleration due to gravity.
where:
θ = angle of repose or angle where the implant is on the
s and Eq 2 becomes:
verge of sliding.
τ ,Lµmg (4)
magnetic
7.4.3 Procedure for Low Friction Surface Method:
7.4.3.5 If magnetically induced torque is observed and the
7.4.3.1 Place the test device on the low friction surface that
device rotates to align with the static magnetic field, then
is positioned on the x-z plane (the horizontal surface) as near
furthertestingaccordingtotheTorsionalSpringMethodorthe
as practical to the isocenter of the MR system (x=y=z=0).
Pulley Method shall be conducted.
Orientthetestdevicesothatoneprincipalaxisisalignedinthe
z-direction.
7.5 Torsional Spring Method:
7.4.3.2 Rotate the test device in 45° increments about the
7.5.1 Example test fixtures are depicted in Figs. 3-5.A
isocenter (on the x-z plane) until a full 360° of rotation is
sturdy structure supporting a holding platform supported by a
completed.After each 45° rotation, observe the test object for
torsion spring is used. Apparatus materials shall be non-
alignment or rotation of the device with the static magnetic
ferromagnetic.
field. Record any motion of the test device.
7.5.1.1 The test device may be taped or otherwise attached
7.4.3.3 Repeat 7.4.3.1 and 7.4.3.2 two additional times for
to the holding platform.
the other two principal axes of the test device.
7.5.1.2 An angle measurement tool (a protractor, for ex-
7.4.3.4 If no motion is observed and the device remained
ample) with the ability to measure in 1° increments shall be
motionless, then the magnetically induced torque is less than
attached to the apparatus in order to be able to measure the
theproductofthefrictionforcebetweenthedeviceandthelow
angle of rotation of the torsional spring.
friction surface and the longest dimension of the device, as
7.5.1.3 The equilibrium angle of the torsion spring outside
the MR system’s static magnetic field represents the zero
torque angle.
7.5.1.4 The torque inside the MR System at isocenter is
equal to the product of the deflection angle and the torsional
spring constant.
7.5.1.5 The torsional spring diameter should be chosen so
that the maximal deflection angle is less than 25°.
7.5.1.6 The sensitivity of the torque measurement apparatus
must be greater than 0.10 of the acceptance criterion.
FIG. 1 Example of Low Friction Apparatus Including Device (i.e.,
Stent) 7.5.2 Procedure:
F2213 − 17
FIG. 3 Diagram of Example of Torsion Spring Apparatus
NOTE 1—The angular reference marker is used to locate the angular marks on protractors connected to the bottom mount and the holding platform.
FIG. 4 Photograph of Apparatus for Measurement of Magnetic Torque
NOTE 1—The turning knob is used to rotate the mounts supporting the torsional pendulum.
7.5.2.1 The test device is placed on the holding platform next equilibrium position. Measure the deflection angle as
with one of its principal axes in the vertical direction. The
...
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. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F2213 − 06 (Reapproved 2011) F2213 − 17
Standard Test Method for
Measurement of Magnetically Induced Torque on Medical
Devices in the Magnetic Resonance Environment
This standard is issued under the fixed designation F2213; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the measurement of the magnetically induced torque produced by the static magnetic field in the
magnetic resonance environment on medical devices and the comparison of that torque to the equivalent torque applied by the
gravitational force to the implant.a user-specified acceptance criterion.
1.2 This test method does not address other possible safety issues which include may include, but are not limited to issues of
magnetically induced force due to spatial gradients in the static magnetic field, RF heating, induced heating, to, magnetically
induced deflection force, tissue heating, device malfunction, imaging artifacts, acoustic noise, interaction among devices, and the
functionality of the device and the MR system.
1.3 The torque considered here is the magneto-static torque due to the interaction of the MRI static magnetic field with the
magnetization inof the implant. The dynamic torque due to interaction of the static field with eddy currents induced in a rotating
device is not addressed in this test method. Currents Torque induced by currents in lead wires may induce a torque as well.is not
addressed by this standard.
1.4 The sensitivity of the torque measurement apparatus must be greater thanmethods in this standard are applicable for MR
systems with a horizontal magnetic field. Not all of the methods described in this standard are applicable for use in an MR system
with a vertical magnetic field. The Suspension Method and the Low Friction Surface Method require gravity to be orthogonal to
the magnetically induced torsion and may not be performed using a vertical magnetic field. The Torsional Spring and Pulley
Methods can be adapted to work in a vertical magnetic field, however the example apparatus are not appropriate for ⁄10 the “gravity
torque,” the product of the device’s maximum linear dimension and its weight.use in a vertical magnetic field. The Calculation
Based on Measured Displacement Force Method is independent of the MR system and thus could be used for an MR system with
a vertical magnetic field.
1.5 The values stated in SI 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 responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
F2052 Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in the Magnetic
Resonance Environment
F2119 Test Method for Evaluation of MR Image Artifacts from Passive Implants
F2182 Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants During Magnetic
Resonance Imaging
This test method is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.15 on Material Test Methods.
Current edition approved Oct. 1, 2011Sept. 1, 2017. Published October 2011October 2017. Originally approved in 2002. Last previous edition approved in 20062011 as
F2213 – 06.F2213 – 06 (2011). DOI: 10.1520/F2213-06R11.10.1520/F2213-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2213 − 17
F2503 Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment
2.2 Other Standards:
IEC 60601-2-33 Ed. 2.0 Medical Electrical Equipment—Part 2: Particular Requirements for the Safety of Magnetic Resonance
Equipment for Medical Diagnosis, 2002Medical electrical equipment - Part 2-33: Particular requirements for the basic safety
and essential performance of magnetic resonance equipment for medical diagnosis
ISO 13485:2003(E)13485 Medical Devices—Quality Management Systems—Requirements for Regulatory Purposes, definition
3.7devices -- Quality management systems -- Requirements for regulatory purposes
ISO TS 10974 Assessment of the safety of magnetic resonance imaging for patients with an active implantable medical device
3. Terminology
3.1 Definitions—Definitions:For the purposes of this test method, the definitions in 3.1.1 – 3.1.18 shall apply:
3.1.1 diamagnetic material—material, n—a material whose relative permeability is less than unity.
3.1.2 ferromagnetic material—material, n—a material whose magnetic moments are ordered and parallel producing magneti-
zation in one direction.
3.1.3 magnetic induction or magnetic flux density (B in T)—T), n—that magnetic vector quantity which at any point in a
magnetic field is measured either by the mechanical force experienced by an element of electric current at the point, or by the
electromotive force induced in an elementary loop during any change in flux linkages with the loop at the point. The magnetic
induction is frequently referred to as the magnetic field. B is the static field in an MR system. Plain type indicates a scalar (for
example, B) and bold type indicates a vector (for example, B).
3.1.4 magnetic field strength (H in A/m)—A/m), n—strength of the applied magnetic field.
3.1.5 magnetic resonance (MR)—(MR), n—resonant absorption of electromagnetic energy by an ensemble of atomic particle
situated in a magnetic field.
3.1.6 magnetic resonance diagnostic device—a device intended for general diagnostic use to present images which reflect the
spatial distribution or magnetic resonance spectra, or both, which reflect frequency and distribution of nuclei exhibiting nuclear
magnetic resonance. Other physical parameters derived from the images or spectra, or both, may also be produced.
3.1.6 magnetic resonance (MR) environment—environment, n—volume within the 0.50 mT (5 gauss (G)) line of an MR system,
which includes the entire three dimensional three-dimensional volume of space surrounding the MR scanner. For cases where the
0.50 mT line is contained within the Faraday shielded volume, the entire room shall be considered the MR environment.
3.1.7 magnetic resonance equipment—equipment, n—medical electrical equipment which is intended for in-vivomagnetic
resonance examination of a patient. The MR equipment comprises all parts in hardware and software from the supply mains to
the display monitor. The MR equipment is a Programmable Electrical Medical System (PEMS). IEC 60601-2-33
3.1.9 magnetic resonance examination (MR Examination)—process of acquiring data by magnetic resonance from a patient.
3.1.8 magnetic resonance imaging (MRI)—(MRI), n—imaging technique that uses static and time varying time-varying
magnetic fields to provide images of tissue by the magnetic resonance of nuclei.
3.1.9 magnetic resonance system (MR System)—System), n—ensemble of MR equipment, accessories including means for
display, control, energy supplies, and the MR environment.
IEC 60601–2–3360601-2-33
3.1.10 magnetically induced displacement force—force, n—force produced when a magnetic object is exposed to the spatial
gradient of a magnetic field. This force will tend to cause the object to translate in the gradient field.
3.1.11 magnetically induced torque—torque, n—torque produced when a magnetic object is exposed to a magnetic field. This
torque will tend to cause the object to align itself along the magnetic field in an equilibrium direction that induces no torque.
3.1.12 magnetization (M in T)—T), n—magnetic moment per unit volume.volume
3.1.13 medical device—device, n—any instrument, apparatus, implement, machine, appliance, implant, in vitro reagent or
calilbrator,calibrator, software, material, or other similar or related article, intended by the manufacturer to be used, alone or in
combination, for human beings for one or more of the specific purpose(s) of:
(1) diagnosis, prevention, monitoring, treatment, or alleviation of disease,
(2) diagnosis, monitoring, treatment, alleviation of, or compensation for an injury,
(3) investigation, replacement, modification, or support of the anatomy 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 of in vitro examination of specimens derived from the human body, and which does not achieve
its primary intended action in or on the human body by pharmacological, immunological, or metabolic means, but which may be assisted in its function
by such means.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Specifically, definition 3.11.
F2213 − 17
(1) diagnosis, prevention, monitoring, treatment, or alleviation of disease;
(2) diagnosis, monitoring, treatment, alleviation of, or compensation for an injury;
(3) investigation, replacement, modification, or support of the anatomy 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 of in vitro examination of specimens derived from the human body, and which does not achieve
its primary intended action in or on the human body by pharmacological, immunological, or metabolic means, but which may be assisted in its function
by such means.
ISO 13485
3.1.14 paramagnetic material—material, n—a material having a relative permeability which is slightly greater than unity, and
which is practically independent of the magnetizing force.
3.1.15 passive implant—implant, n—an implant that serves its function without the supply of electrical power.
3.1.16 tesla, (T)—(T), n—the SI unit of magnetic induction equal to 10 gauss (G).
4. Summary of Test Method
4.1 The static magnetic field associated with an MR system produces a torque on a device that acts to align the long axis of
the object with the direction of the magnetic field. Five methods for measurement or assessment of magnetically induced torque
are given in this standard: the Suspension Method, the Low Friction Surface Method, the Torsional Spring Method, the Pulley
Method, and the Calculation Based on Measured Displacement Force Method.
4.2 The Suspension Method and the Low Friction Surface Method are not appropriate for devices for which the magnetically
induced torque is expected to be greater than the torque due to gravity.
4.3 The Low Friction Surface Method is performed by placing the device on a low friction non-metallic, non-conductive surface
as near as practical to the isocenter of the MR system. The device is then rotated in defined angular increments while alignment
or rotation of the device with the static magnetic field is observed. If rotation of the device is not observed, an upper bound on
the magnetically induced torque is estimated using the coefficient of friction between the surface and the device and the weight
of the device. If alignment or rotation of the device is observed, then either the Torsional Spring Method or the Pulley Method shall
be performed. The coefficient of friction is calculated from the device weight and the angle of repose (the angle in which the
implant is on the verge of sliding off the low friction surface) which is measured outside the MR environment.
4.4 The static field in a magnetic resonance system produces a torque on a device that acts to align the long axis of the object
with the magnetic field. The torque is evaluated using a torsional pendulum method. Torsion Spring Method determines the
magnetically induced torque using a torsion pendulum. A device is placed on a holder suspended by a torsionaltorsion spring. The
apparatus is placed in the center of the magnetic resonance equipment magnet where the magnetic field is uniform. The torque is
determined from the measurement of the deflection angle of the holder from its equilibrium position. The frame holding the spring
and holder assembly is rotated and the torque as a function of angle of the implant is determined. The maximal magnetic torque
is compared to the worst case gravitygravitational torque, defined as the product of the maximum linear dimension of the device
and the device weight.
4.5 The Pulley Method allows determination of the maximum magnetically induced torque of the device using a low friction
pulley attached to a rotating platform. The device is fixed on the platform while positioning the device to be centered as near as
practical to isocenter of the MR system. Using a lightweight string attached to the pulley and a force gauge, the platform is rotated
by pulling the force gauge in a direct line away from the torque fixture. The maximum torque is determined by using the maximum
reading from the force gauge.
4.6 The Suspension Method is a qualitative method that is performed by suspending the device by a lightweight string in a
location as near as practical to the isocenter of the MR system. The device is then rotated in defined angular increments while
movement or rotation of the device to align with the static magnetic field is observed. If rotation of the device is not observed,
the magnetically induced torque is small and no further evaluation is required. If rotation of the device is observed, then the Low
Friction Surface Method, the Torsional Spring Method, or the Pulley Method shall be performed.
4.7 The Calculation Based on Measured Displacement Force Method provides an upper bound for the magnetically induced
torque based on magnetically induced displacement force measurements using Test Method F2052. This method is most
appropriate for devices which are composed of only one material; however it may also be used with devices composed of multiple
materials (see 7.8.2.2). This method is not appropriate for devices that contain magnets or ferromagnetic material.
5. Significance and Use
5.1 This test method is one of those required to determine if the presence of a medical device may cause injury during a
magnetic resonance examination and in the magnetic resonance environment. Other safety issues which should be addressed
include but may not be limited to magnetically induced force (see Test Method F2052) and ), RF heating (see Test Method F2182).
F2213 − 17
The terms and icons in Practice ), and image artifact (see Test Method F2503F2119 should be used to mark the device for safety
in the magnetic resonance environment.). ISO TS 10974 addresses hazards produced by active implantable medical devices in the
MR Environment.
5.2 The terms MR Conditional, MR Safe, and MR Unsafe together with the corresponding icons in Practice F2503 shall be used
to mark the device for safety in the MR environment.
5.3 If the maximal The acceptance criterion associated with this test shall be justified. If the maximum magnetically induced
torque is less than the product of the longest dimension of the medical device and its weight, then the magnetically induced
deflection torque is less than the worst case torque on the device due to gravity. For this condition, it is assumed that any risk
imposed by the application of the magnetically induced torque is no greater than any risk imposed by normal daily activity in the
Earth’s gravitational field. This is conservative; itconservative. It is possible that greater torques also would not pose a hazard to
the patient.hazard. (For example, device position with respect to adjacent tissue, tissue ingrowth, or other mechanisms may act to
prevent device movement or forces produced by a magnetically induced torque that are greater than the torque due to gravity from
causing harm to adjacent tissue.)
5.4 This test method alone is not sufficient for determining if an implant is safe in the MR environment.
5.4 The sensitivity of the torque measurement apparatus must be greater than ⁄10 the “gravity torque,” the product of device
weight and the largest linear dimension.
5.5 The magnetically induced torque considered here in this standard is the magneto-static torque due to the interaction of the
MRI static magnetic field with the magnetization in the implant. The dynamic torque due to interaction of the static field with eddy
currents induced in a rotating device is not addressed in this test method. Currents in lead wires may induce a torque as well.
6. Apparatus
6.1 The test fixture is depicted in Fig. 1. It consists of a sturdy structure supporting a holding platform supported by a torsional
spring. Materials should be non-ferromagnetic. The device may be taped or otherwise attached to the holding platform. The
supporting structure will have fixed to it a protractor with 1° graduated markings and the holding platform will have a marker so
that the angle between the basket and the support structure can be measured. The supporting structure is rotated with the turning
knob. The equilibrium angle between the supporting structure and the holding platform outside the magnetic field represents the
zero torque angle. The torque inside the magnet is equal to the product of the deflection angle and spring constant. The torsional
spring diameter should be chosen so that the maximal deflection angle is less than 25°. A photograph of a torque apparatus is shown
in Fig. 2.
6. Test Specimens
6.1 For purposes of device qualification, the device evaluated according to this test method should be representative of
manufactured devices. The device should be sterilized, unless sterilization is not expected to affect the relevant properties of the
device (for example: magnetic susceptibility, weight)
6.2 For purposes of device qualification, any alteration from the finished condition should be reported. For instance, if sections
are removed from the device for testing or if the device has not been sterilized, this should be reported.
7. Test Specimens
7.1 For purposes of device qualification, the device evaluated according to this test method should be representative of
manufactured devices that have been processed to a finished condition (for example, sterilized).
7.2 For purposes of device qualification, any alteration from the finished condition should be reported. For instance, if sections
are cut from the device for testing, this should be reported.
7. Procedure
7.1 Selection of Test Device:
FIG. 1 Example of Low Friction Apparatus Including Device (i.e., Stent)
F2213 − 17
FIG. 2 Diagram of Angle of Repose (ϴ) Measurement Method
7.1.1 The test sample shall be worst case for the device under test. Provide a rationale for the selection of the test sample as
worst case. For instance, for devices that are available in multiple sizes and/or configurations, provide a rationale supporting the
chosen test sample as worst case for the entire range of device sizes and/or configurations.
7.1.1.1 It might be appropriate to test only a relevant section of a device (for example, for a flexible device with only a small
metallic portion, test only the metallic portion of the device). A justification for the selected portion of the device shall be provided.
Mass, linear dimension, and material magnetic susceptibility shall be considered. The worst case combination will likely include
components with the greatest product of the implant mass and the maximum linear dimension when compared to other product
combinations.
7.2 Test Device Orientation:
7.2.1 The test device shall be tested with each principal axis of the test device oriented parallel to the MR system’s static
magnetic field, unless a rationale for a specific worst case orientation is determined. Such a rationale may include consideration
of the clinically possible orientations of the test device in relation to B . Note, it is possible for the worst case orientation to be
with the principal axes of the test device at an oblique(s) angle with respect to B . Also, lead wires should be arranged in a manner
that is worst case or representative of the in vivo configuration. If applicable, the effect of current in lead wires should be
considered.
7.3 Coordinate System:
7.3.1 Use a right handed Cartesian coordinate system with origin (x=y=z=0) at the isocenter of the MR system. The z-axis is
parallel to the MR system bore with the positive direction pointing from the patient table into the bore. The y-axis is vertical with
the positive direction up.
7.4 The Low Friction Surface Method:
7.4.1 The Low Friction Surface Method apparatus consists of a low friction non-metallic, non-conductive surface as shown in
Fig. 1.
7.4.2 Determination of Coeffıcient of Friction Between the Implant and the Low Friction Surface:
7.4.2.1 Perform this process outside the MR environment where the earth’s magnetic field is the only magnetic field acting on
the device.
7.4.2.2 Place the test device on the surface (an acrylic sheet, for example). If the device has sides with varied friction
characteristics, use the side with lower friction. Fix one end of the low friction surface so that it will not slide when the other end
is lifted.
7.4.2.3 Slowly raise the surface until it reaches the angle of repose (the angle at which the device is on the verge of sliding)
as shown in Fig. 2. This will require raising the device to an angle at which the test device does slide and then repeating the process
to determine the angle of repose. Make sure the device slides and does not roll.
7.4.2.4 Calculate the coefficient of friction (μ) using Eq 1.
μ 5 tanθ (1)
s
where:
θ = angle of repose or angle where the implant is on the verge of sliding.
s
7.4.3 Procedure for Low Friction Surface Method:
7.4.3.1 Place the test device on the low friction surface that is positioned on the x-z plane (the horizontal surface) as near as
practical to the isocenter of the MR system (x=y=z=0). Orient the test device so that one principal axis is aligned in the z-direction.
7.4.3.2 Rotate the test device in 45° increments about the isocenter (on the x-z plane) until a full 360° of rotation is completed.
After each 45° rotation, observe the test object for alignment or rotation of the device with the static magnetic field. Record any
motion of the test device.
7.4.3.3 Repeat 7.4.3.1 and 7.4.3.2 two additional times for the other two principal axes of the test device.
7.4.3.4 If no motion is observed and the device remained motionless, then the magnetically induced torque is less than the
product of the friction force between the device and the low friction surface and the longest dimension of the device, as defined
in Eq 2 and which may be calculated from the device length, weight, and coefficient of friction determined in 7.4.2.
τ ,L F (2)
magnetic f
F2213 − 17
where:
τ = magnetically induced torque,
magnetic
L = longest dimension of the test device, and
F = friction force between the test device and the low friction surface.
f
The friction force, F , between the test device and the low friction surface is given in Eq 3.
f
F 5 μmg (3)
f
where:
F = friction force between the test device and the low friction surface,
f
μ = coefficient of friction between the test device and the low friction surface (determined in 7.4.2),
m = mass of the device, and
g = acceleration due to gravity.
and Eq 2 becomes:
τ ,Lμmg (4)
magnetic
7.4.3.5 If magnetically induced torque is observed and the device rotates to align with the static magnetic field, then further
testing according to the Torsional Spring Method or the Pulley Method shall be conducted.
7.5 Fig. 1 depicts the test fixture, which is placed in the middle of the magnet where the magnetic field is uniform. The test
device is placed on the holding platform with one of its principal axes in the vertical direction. The entire apparatus is placed in
the center of the magnet in the region of uniform magnetic field. Rotate the fixed base and measure the deflection of the device
with respect to the base at 10° increments for angles between 0° and 360°. Note that at angular values where the angular derivative
of the torque changes sign, there will be an abrupt change in deflection angle as the device swings to the next equilibrium position.
Try to measure the deflection angle as close as possible to this swing so that the maximal torque will be determined.Torsional
Spring Method:
7.5.1 Example test fixtures are depicted in Figs. 3-5. A sturdy structure supporting a holding platform supported by a torsion
spring is used. Apparatus materials shall be non-ferromagnetic.
7.5.1.1 The test device may be taped or otherwise attached to the holding platform.
7.5.1.2 An angle measurement tool (a protractor, for example) with the ability to measure in 1° increments shall be attached to
the apparatus in order to be able to measure the angle of rotation of the torsional spring.
7.5.1.3 The equilibrium angle of the torsion spring outside the MR system’s static magnetic field represents the zero torque
angle.
FIG. 3 Diagram of Example of Torsion Spring Apparatus
NOTE 1—The angular reference marker is used to locate the angular marks on protractors connected to the bottom mount and the holding platform.
F2213 − 17
FIG. 14 Diagram of the Torque ApparatusPhotograph of Apparatus for Measurement of Magnetic Torque
NOTE 1—The turning knob is used to rotate the mounts supporting the torsional pendulum.
FIG. 25 Photograph of an Example Apparatus for Measurement of
Magnetic Torque (Different Apparatus From Those Shown in
Figs. 3 and 4)
7.5.1.4 The torque inside the MR System at isocenter is equal to the product of the deflection angle and the torsional spring
constant.
7.5.1.5 The torsional spring diameter should be chosen so that the maximal deflection angle is less than 25°.
7.5.1.6 The sensitivity of the torque measurement apparatus must be greater than 0.10 of the acceptance criterion.
7.5.2 Procedure:
7.5.2.1 The test device is placed on the holding platform with one of its principal axes in the vertical direction. The entire
apparatus is placed in the center of the MR system’s magnet in the region of uniform static magnetic field.
7.5.2.2 Rotate the fixed base and measure the deflection of the device with respect to the base at 10° increments for angles
between 0° and 360°. Note that at angular values where the angular derivative of the torque changes sign, there will be an abrupt
F2213 − 17
change in deflection angle as the device swings to the next equilibrium position. Measure the deflection angle as close as possible
to this swing so that the maximal torque will be determined.
7.5.2.3 Repeat the proce
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La norme ASTM F2213-17, intitulée "Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment", constitue un cadre essentiel pour évaluer la sécurité des dispositifs médicaux dans un environnement d'IRM. Son champ d'application est clairement défini, visant à mesurer le couple magnifiquement induit par le champ magnétique statique, tout en fournissant un critère d'acceptation spécifié par l'utilisateur. L'un des atouts majeurs de cette norme réside dans sa capacité à aborder les risques associés à l'utilisation de dispositifs médicaux en IRM, en se concentrant sur les couples magnétiquement induits, ce qui est crucial pour éviter des blessures potentielles. La norme reconnaît également que le couple induit magnétique doit être justifié par rapport à la dimension et au poids du dispositif, un aspect qui renforce la rigueur des évaluations de sécurité. De plus, le cadre proposé par ASTM F2213-17 est pertinent pour divers systèmes d'IRM, bien qu'il ait des limitations en ce qui concerne les champs magnétiques verticaux. Cela souligne la nuance et la précision avec lesquelles la norme est écrite, ce qui est essentiel pour les professionnels de la santé et les ingénieurs travaillant avec des dispositifs implantables. Le fait que cette norme soit spécifiquement axée sur le couple magnétique statique et n'aborde pas d'autres questions de sécurité telles que la déviation magnétique ou la chaleur des tissus, montre une spécialisation qui peut s’avérer précieuse dans des situations spécifiques. En outre, la norme recommande l'utilisation de terminologies appropriées telles que "MR Conditional", "MR Safe" et "MR Unsafe", offrant ainsi un cadre de communication utile pour l'étiquetage et la classification des dispositifs. Cela aide à minimiser les confusions et à assurer un niveau de sécurité approprié pour les utilisateurs. En somme, ASTM F2213-17 est une norme robuste et ciblée qui répond efficacement aux besoins de sécurité dans l’environnement d'IRM en mesurant le couple magnétique induit sur les dispositifs médicaux. Cela en fait un outil indispensable pour évaluer les risques potentiels tout en respectant des critères d'acceptation étayés et des méthodes d'essai bien définies.
Die ASTM F2213-17 stellt einen wesentlichen Standard für die Messung des magnetisch induzierten Drehmoments auf medizinischen Geräten im Umfeld der Magnetresonanztomographie (MRT) dar. Der Umfang des Standards umfasst die Bestimmung, ob medizinische Geräte im magnetischen Resonanzumfeld potenziell Verletzungen verursachen können, was entscheidend für die Sicherheit der Patienten ist. Dieser Standard ist ein wichtiges Instrument, um sicherzustellen, dass medizinische Geräte als MR-sicher oder MR-bedingt eingestuft werden können, basierend auf klaren Kriterien. Ein herausragendes Merkmal des ASTM F2213-17 ist die Methodik zur Messung des magneto-statischen Drehmoments, die aus der Wechselwirkung des statischen Magnetfeldes der MRT mit der Magnetisierung des Implantats resultiert. Diese präzise Fokussierung auf das magnetisch induzierte Drehmoment bietet eine differenzierte Betrachtungsweise, während potenzielle Gefahren durch andere Sicherheitsfaktoren wie magnetisch induzierte Abhebelkräfte oder Gewebeerwärmung nicht direkt behandelt werden. Diese Einschränkung wird jedoch klar erläutert, wodurch Anwender auf die Notwendigkeit weiterer Sicherheitsprüfungen hingewiesen werden. Ein weiterer bedeutender Aspekt des Standards ist das Akzeptanzkriterium für das gemessene Drehmoment. Dabei wird durch eine konservative Annahme, dass das maximale magnetisch induzierte Drehmoment kein größeres Risiko darstellt als die normalen täglichen Aktivitäten im Erdschwerefeld, eine sichere Grundlage für die Bewertung geboten. Diese Herangehensweise ist besonders relevant, da sie eine detaillierte Risikoanalyse im Kontext des MRT-Umfelds ermöglicht. Die Anwendbarkeit der Methoden für MRT-Systeme mit horizontalem Magnetfeld ist ein weiterer Vorteil des ASTM F2213-17. Obwohl einige Methoden nicht für vertikale Magnetfelder geeignet sind, bietet der Standard dennoch flexible Ansätze, um präzise Messungen in verschiedenen Einsatzszenarien zu gewährleisten. Die Notwendigkeit, spezifische Methoden entsprechend den Magnetfeld-Gegebenheiten auszuwählen, zeigt das Engagement des Standards für genaue und relevante Testergebnisse. Insgesamt ist die ASTM F2213-17 ein unverzichtbarer Standard, der nicht nurgerichtet ist auf die Sicherheit von medizinischen Geräten im MRT-Umfeld, sondern auch auf eine umfassende Methodik zur Bewertung von magnetisch induziertem Drehmoment fokussiert. Die Relevanz dieses Standards für Hersteller, Kliniken und andere anspruchsvolle Akteure im Bereich der Medizin ist unbestreitbar und spielt eine entscheidende Rolle bei der Sicherstellung der Patientensicherheit im Zusammenhang mit MRT-verwandten Technologien.
ASTM F2213-17は、医療機器が磁気共鳴環境において引き起こす可能性のある磁気誘導トルクを測定するための標準試験方法として非常に重要です。この標準の範囲は、医療機器が磁気共鳴環境に存在する際のリスクを評価することにあります。具体的には、磁気誘導力、RF加熱、画像アーティファクトなど、他の安全性の問題にも言及されていますが、これらは主に他の試験方法に委ねられています。 この標準の最大の強みは、医療機器に対するリスクを評価し、それに基づいて安全性の基準を定義できる点です。特に、医療機器の長さや重さを考慮に入れた最大磁気誘導トルクの評価により、通常の重力によるリスクと比較できるため、保守的かつ合理的なアプローチを提供しています。これにより、医療機器の利用者は、日常的な活動のリスクレベルにおいて、磁気誘導トルクの影響がそれほど大きくないことが確認でき、安全な使用が促進されます。 さらに、ASTM F2213-17は、水平磁場を持つMRIシステムに対して適用可能な方法を提供しており、実際の検査環境に応じた柔軟性があります。これは、医療技術分野での研究や開発において非常に重要であり、医療機器の設計時における基準となります。 しかしながら、標準が示すように、この試験方法単独ではインプラントがMRI環境で安全であるかどうかを決定するには不十分です。そのため、これを踏まえて他の安全性試験と組み合わせて使用する必要があります。最終的には、ASTM F2213-17は医学的な判断や評価を行う際に不可欠なツールを固定し、医療機器の安全性向上を目指すための重要な役割を果たしています。
The ASTM F2213-17 standard provides a crucial framework for assessing the safety of medical devices in the magnetic resonance environment by outlining a standardized test method for measuring magnetically induced torque. This standard is notable for its comprehensive scope, directing attention to the specific magneto-static torque that results from the interaction between the MRI's static magnetic field and the device's magnetization. By establishing a protocol for measuring this torque and comparing it to user-specified acceptance criteria, the standard serves as a foundational tool in ensuring device safety. One of the key strengths of ASTM F2213-17 is its emphasis on the importance of clearly defining the terms MR Conditional, MR Safe, and MR Unsafe, alongside their respective icons. This approach not only enhances clarity in device markings but also fosters a better understanding of the implications of these safety classifications among medical personnel, patients, and device manufacturers. Furthermore, the standard wisely acknowledges that the magnetically induced torque is only one aspect of safety in the MR environment. By delineating the test's limitations and clearly stating that it does not consider other significant safety concerns-such as magnetically induced deflection forces, tissue heating, or imaging artifacts-it prevents the misinterpretation of the test as a comprehensive safety measure. The adoption of various test methods, while focused primarily on horizontal magnetic fields, also enables adaptation for vertical configurations, demonstrating flexibility in practical applications. This adaptability ensures that the standard remains relevant across different MRI systems, facilitating its broad implementation in diverse medical settings. The use of SI units as the standard for measurement adds to the document’s clarity and uniformity, making it accessible for international use and fostering consistency in testing and reporting outcomes. Overall, ASTM F2213-17 is an integral standard that balances detailed technical guidance with practical applicability, affirming its relevance to the ongoing development and safety assessment of medical devices in the increasingly critical magnetic resonance environment.
ASTM F2213-17 표준은 자기 공명 환경에서 의료 기기에 의해 유도된 자력 토크의 측정을 위한 시험 방법을 제시합니다. 이 표준은 의료 기기의 존재가 자기 공명 환경에서 부상을 초래할 수 있는지를 판단하는 데 필수적인 시험 방법 중 하나로, 안전성을 평가하기 위한 기준을 제공합니다. 표준의 주요 강점은 의료 기기의 크기와 무게를 바탕으로 특정 자력 토크의 허용 기준을 제시함으로써, 기기가 일반적인 지구 중력과 비교했을 때 위험을 수반하지 않도록 보장한다는 점입니다. 이 표준은 MR 환경에서 자력에 의해 유도된 토크의 측정 방법을 명확하게 기술하고 있으며, 자기 공명 스캐너의 수평 자기장에 적용 가능한 여러 방법을 포함합니다. 특히, Suspension Method와 Low Friction Surface Method는 중력이 자력 토크와 직각을 이루어야 하므로 수직 자기장에서는 적용할 수 없지만, Torsional Spring 및 Pulley Methods는 수직 자기장에서도 조정하여 사용할 수 있는 가능성을 제공함으로써, 다양한 사용 환경에 대한 유연성을 제공합니다. 또한, 이 표준에서 논의된 자력 토크는 MRI의 정적 자기장과 이식물의 자화 간의 상호작용으로 발생하는 마그네토-정적 토크로 한정되어 있어, 다른 잠재적인 안전 문제들, 예를 들어 조직 열화, 장치 고장, 및 이미징 아티팩트 등은 다루지 않는다는 점에서 다소 제한적입니다. 그러나 이러한 명확한 범위 설정은 의료 기기의 평가 시 보다 집중적이고 정확한 데이터를 얻을 수 있게 합니다. ASTM F2213-17 표준은 의료 기기가 MRI 환경에서 안전하게 사용될 수 있도록 하는 데 중요한 역할을 하며, 정확한 측정 방법을 통해 의사결정에도 기여할 수 있도록 하고 있습니다. 이 표준은 의료 기기 제조사와 사용자가 자기 공명 환경에서의 안전성을 평가하는 데 필수적인 도구로 활용될 것입니다.
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