ASTM F2213-06
(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
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 F 2052) and RF heating (see Test Method F 2182). The terms and icons in Practice F 2503 should be used to mark the device for safety in the magnetic resonance environment.
If the maximal 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’gravitational field. This is conservative; it is possible that greater torques would not pose a hazard to the patient.
This test method alone is not sufficient for determining if an implant is safe in the MR environment.
The sensitivity of the torque measurement apparatus must be greater than 1/10 the “gravity torque,” the product of device weight and the largest linear dimension.
The torque considered here 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.
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.
1.2 This test method does not address other possible safety issues which include but are not limited to issues of magnetically induced force due to spatial gradients in the static magnetic field, RF heating, induced heating, 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 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.
1.4 The sensitivity of the torque measurement apparatus must be greater than 1/10 the "gravity torque," the product of the device's maximum linear dimension and its weight.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: F2213 – 06
Standard Test Method for
Measurement of Magnetically Induced Torque on Medical
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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 from Passive Implants
F2182 Test Method for Measurement of Radio Frequency
1.1 This test method covers the measurement of the mag-
Induced Heating Near Passive Implants During Magnetic
netically induced torque produced by the static magnetic field
Resonance Imaging
inthemagneticresonanceenvironmentonmedicaldevicesand
F2503 Practice for Marking Medical Devices and Other
the comparison of that torque to the equivalent torque applied
Items for Safety in the Magnetic Resonance Environment
by the gravitational force to the implant.
2.2 Other Standards:
1.2 This test method does not address other possible safety
IEC 60601-2-33 Ed. 2.0 Medical Electrical Equipment—
issues which include but are not limited to issues of magneti-
Part 2: Particular Requirements for the Safety of Magnetic
cally induced force due to spatial gradients in the static
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Resonance Equipment for Medical Diagnosis, 2002
magnetic field, RF heating, induced heating, acoustic noise,
ISO 13485:2003(E) Medical Devices—Quality Manage-
interaction among devices, and the functionality of the device
ment Systems—Requirements for Regulatory Purposes,
and the MR system.
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definition 3.7
1.3 The torque considered here is the magneto-static torque
due to the interaction of the MRI static magnetic field with the
3. Terminology
magnetization in the implant. The dynamic torque due to
3.1 Definitions—For the purposes of this test method, the
interaction of the static field with eddy currents induced in a
definitions in 3.1.1-3.1.18 shall apply:
rotating device is not addressed in this test method. Currents in
3.1.1 diamagnetic material—a material whose relative per-
lead wires may induce a torque as well.
meability is less than unity.
1.4 The sensitivity of the torque measurement apparatus
1 3.1.2 ferromagnetic material—a material whose magnetic
mustbegreaterthan ⁄10the“gravitytorque,”theproductofthe
moments are ordered and parallel producing magnetization in
device’s maximum linear dimension and its weight.
one direction.
1.5 This standard does not purport to address all of the
3.1.3 magnetic induction or magnetic flux density (B in
safety concerns, if any, associated with its use. It is the
T)—that magnetic vector quantity which at any point in a
responsibility of the user of this standard to establish appro-
magnetic field is measured either by the mechanical force
priate safety and health practices and determine the applica-
experiencedbyanelementofelectriccurrentatthepoint,orby
bility of regulatory limitations prior to use.
the electromotive force induced in an elementary loop during
2. Referenced Documents any change in flux linkages with the loop at the point. The
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magnetic induction is frequently referred to as the magnetic
2.1 ASTM Standards:
field. B isthestaticfieldinanMRsystem.Plaintypeindicates
F2052 Test Method for Measurement of Magnetically In- 0
a scalar (for example, B) and bold type indicates a vector (for
duced Displacement Force on Medical Devices in the
example,B).
Magnetic Resonance Environment
3.1.4 magnetic field strength (H in A/m)—strength of the
F2119 Test Method for Evaluation of MR Image Artifacts
applied magnetic field.
3.1.5 magnetic resonance (MR)—resonant absorption of
electromagnetic energy by an ensemble of atomic particle
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This test method is under the jurisdiction ofASTM Committee F04 on Medical
situated in a magnetic field.
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
3.1.6 magnetic resonance diagnostic device—a device in-
F04.15 on Material Test Methods.
Current edition approved May 1, 2006. Published June 2006. Originally
tended for general diagnostic use to present images which
approved in 2002. Last previous edition approved in 2004 as F2213 – 04. DOI:
reflectthespatialdistributionormagneticresonancespectra,or
10.1520/F2213-06.
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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
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the ASTM website. 4th Floor, New York, NY 10036.
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