YY/T 0987.2-2016 PDF English
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Implants for surgery--Magnetic resonance compatibility--Part 2: Magnetically induced displacement force test method
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YY/T 0987.2-2016: PDF in English (YYT 0987.2-2016) YY/T 0987.2-2016
YY
PHARMACEUTICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 11.040.40
C 35
Implants for Surgery - Magnetic Resonance
Compatibility - Part 2. Magnetically Induced
Displacement Force Test Method
外科植入物 磁共振兼容性
ISSUED ON. MARCH 23, 2016
IMPLEMENTED ON. JANUARY 1, 2017
Issued by. China Food and Drug Administration
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Terms and Definitions ... 6
4 Overview of Test Method ... 8
5 Significance and Application ... 8
6 Instruments and Equipment ... 9
7 Test Sample ... 9
8 Procedures ... 9
9 Data Processing ... 11
10 Report ... 11
Appendix A (Informative) Fundamental Principle ... 13
Bibliography ... 16
Implants for Surgery - Magnetic Resonance
Compatibility - Part 2. Magnetically Induced
Displacement Force Test Method
1 Scope
This Part of YY/T 0987 includes test method for magnetically induced displacement
force generated by medical devices as a result of static gradient magnetic field; a
comparison of magnetically induced displacement force and the weight of medical
devices.
This Part does not involve other possible safety questions. These safety questions
include, but are not limited to, magnetically induced torque, radio frequency heating
and radio frequency induced heating, noise, interaction among medical devices,
functions of medical devices and magnetic resonance system.
This Part is applicable to devices that can be hanged through wires. This Part is not
applicable to devices that cannot be hanged through wires. During the test, the weight
of wires used to hang devices shall be less than 1% of the weight of devices being
tested.
The test in this Part shall be conducted in a system, in which, the direction of
magnetically induced displacement force is horizontal.
This Part adopts numerical value under international system of units as the standard;
numerical value in the brackets shall merely be considered as reference.
This Part does not attempt to elaborate all the involved safety questions, even though
those safety questions are related with the usage. Determining appropriate safety and
health specifications and clarifying the applicability of management limit before
application is the responsibility on the users of this Standard.
2 Normative References
The following documents are indispensable to the application of this Standard. In terms
of references with a specified date, only versions with a specified date are applicable
to this Standard. The latest version (including all the modifications) of references
without a specified date is also applicable to this Standard.
YY/T 0987.1 Implants for Surgery - Magnetic Resonance Compatibility - Part 1.
Safety Marking
Magnetic resonance environment refers to the space within 0.5 mT (5G) line in MR
system, including the whole three-dimensional space around MR scanner. When 0.5
mT line is included in Faraday cage, the whole space shall be deemed as magnetic
resonance (MR) environment.
3.7 Magnetic Resonance Equipment
MR Equipment
Magnetic resonance equipment refers to medical electrical equipment that is expected
to be applied to in vivo magnetic resonance examination. Magnetic resonance
equipment includes all hardware and software parts from main power to display
monitor. Magnetic resonance equipment is programmable electrical medical system
(PEMS).
3.8 Magnetic Resonance System
MR System
Magnetic resonance system refers to the combination of magnetic resonance
equipment, accessories (including display, control and energy supply devices) and
controlled entry zone (if provided).
3.9 Magnetic Resonance Examination
MR Examination
Magnetic resonance examination refers to the process of gathering patients’ data
through magnetic resonance.
3.10 Magnetic Resonance; MR
Magnetic resonance refers to atomic particle swarm’s resonance absorption of
electromagnetic field energy in the magnetic field.
3.11 Medical Device
Manufacturer’s expected purposes for medical devices used on human beings, either
independent application or combined application, are as follows (any instruments,
equipment, appliances, materials or other items, including software if necessary).
---Diagnosis, prevention, monitoring, treatment or remission of diseases;
---Diagnosis, monitoring, treatment, remission or compensation of disabilities;
---Study, replacement or adjustment of anatomical or physiological process.
The primary expected effect on body surface and in vivo is not obtained through the
means of pharmacology, immunology or metabolism. However, these means might be
larger static magnetic field gradient is also less than 45°.
This test is insufficient to prove medical devices’ safety in magnetic resonance
environment.
6 Instruments and Equipment
Test device includes a solid non-magnetic bracket, which can hang medical devices to
be tested and do not generate displacement; a protractor (division value. 1°), which is
firmly installed on the bracket. The protractor’s 0° calibration tail is in the vertical
direction; medical device to be tested is hanged on a wire that is connected with the
protractor’s 0° calibration tail. In order to make the weight of the wire neglectable in
comparison with the medical device to be tested, the weight of the wire shall not
exceed 1% of the weight of the medical device. The wire shall be sufficiently long, so
that the medical device can be hanged onto the test device and naturally droop. The
movement of the wire shall not be restricted by the bracket or the protractor; the
hanged wire can be connected to any appropriate location of the medical device.
7 Test Sample
Medical devices which are evaluated in accordance with the test method in this Part
shall be representative finished products that have received final treatment (for
example, sterilization).
Before the test, medical devices to be tested shall not have any form of change.
8 Procedures
Any magnetic items that can generate large gradient horizontal magnetic field are
applicable to this test. Figure 1 illustrates the test device installed on the scanning bed
of MRI system. The medical device to be tested shall be hanged through a wire; the
hanged wire shall coincide with the protractor’s 0° calibration tail. Adjust the location of
the test device, so that the centroid of the medical device is at the point with the
maximum displacement (refer to NOTE). Mark the location with the maximum
displacement. All tests shall be repeatedly conducted in the same location. Grasp the
medical device; maintain the hanged wire in the vertical direction; then, release the
medical device. Record the medical device’s displacement angle from the vertical
location to the nearest 1° location (refer to Figure 2).
Repeat the above procedures. Test each sample for at least 3 times.
In order to place a medical device mostly at the point with the maximum displacement
angle, the medical device shall be bundled. If there is a medical device that uses
bundling item (for example, adhesive tape) in a test, it shall be proved that the extra
9 Data Processing
Use the absolute value of displacement angle measured in Chapter 8 to calculate
the average displacement angle. (The medical device being tested might not be
attracted by magnetic item but be repelled. Hence, in the calculation of the average
displacement angle, the absolute value of displacement angle shall be adopted.)
Through the average displacement angle and the following relational expression
(please refer to Appendix A), medical devices’ average magnetically induced
displacement force can be calculated... Specifically speaking, m signifies
the mass of medical device; g signifies gravity acceleration. If the average value of
is less than 45°, then, magnetically induced displacement force Fm is less than the
gravity force applied to the medical device (the weight of the medical device).
10 Report
In terms of each test sample, report shall include the following content.
a) Product description, including dimension figures or photos (with scale) of
medical devices;
b) Sketch maps or photos of sample configuration in tests;
c) Medical devices’ product identification (such as batch, batch number, model
number, version number, serial number and date of production);
d) Materials (stipulated materials or others);
e) Quantity of test samples and dimensional specification of selected samples;
f) Take the central point of magnetic item as the original point; use Cartesian
coordinates (x, y, z) of the gravity center of the medical device, which is
determined through right-hand screw rule; sketch map of the magnetic item and
the coordinate axis shall also be included. If the magnetic item for test is MR
system, then, the coordinate system needs to be positioned. the vertical
direction shall be y-axis; the horizontal direction of the scanning bed shall be z-
axis;
g) Magnetic field strength amplitude and spatial gradient amplitude
of magnetic field in the location of test;
h) Displacement angle , which is measured through repeated tests in the same
location of test;
Appendix A
(Informative)
Fundamental Principle
A.1 Fundamental Principle of Test Method
The test method in this Part shall be mainly applied to the determination of magnetically
induced displacement force that medical devices receive during magnetic resonance
imaging. It needs to be pointed out that this Part merely provides the test method of
magnetically induced displacement force, and it is impossible to merely depend on the
result of this test to determine medical devices’ safety in magnetic resonance
environment. Displacement force is generated by the spatial gradient of static
magnetic field. The static magnetic field would also generate torque on medical
devices, so that medical devices are always in a consistent direction as the magnetic
field (for example, compass pointer is in a consistent direction as the earth’s magnetic
field). In terms of medical devices that are safe in MR environment, magnetically
induced displacement force and torque shall be less than the displacement force and
torque that the medical devices receive when they are not in large magnetic field space.
For example, the displacement force shall be less than the weight of medical devices;
the torque shall be less than the torque generated by daily activities (might include fast
acceleration of vehicles or roller coasters in amusement park). Other possible safety
questions include, but shall not be limited to, radio frequency heating, radio frequency
induced heating, noise, interaction among medical devices, functions of medical
devices and magnetic resonance system. Although the most commonly seen
environment is 1.5T MR system environment for medical devices, 3T MR system has
entered the market and has been increasingly commonly applied to clinic. It is worth
noticing that safe medical devices in 1.5T scanning system are not necessarily safe in
a system with higher or lower magnetic field strength (for example, 3T or 1T system).
Furthermore, open-ended and cylindrical MR system might also have significant
differences. For example, the static magnetic field spatial gradient of an open-ended
system is obviously higher.
After determining the safety of medical devices, apply the terms and markings provided
in YY/T 0987.1 to the marking. MR safe, MR conditional or MR unsafe. Please see the
terms and definitions in YY/T 0987.1 below.
MR safe---items that do not generate already known hazards in all MR environments.
NOTE. MR safe items include non-conductive and non-magnetic items, for example,
plastic petri dish. Whether items are MR safe can be determined in accordance
with scientific theories, not experimental data.
MR conditional---items that do not generate already known hazards under specific MR
Bibliography
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Foreign Items During Magnetic Resonance Imaging at all Degrees of Freedom,”
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......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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