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Medical endoscopes - Video endoscopes
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YY/T 1587-2018: PDF in English (YYT 1587-2018) YY/T 1587-2018
PHARMACEUTICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 11.040.99
C 40
Medical endoscopes - Video endoscopes
ISSUED ON: JUNE 26, 2018
IMPLEMENTED ON: JULY 01, 2019
Issued by: National Medical Products Administration
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Requirements ... 8
5 Test methods ... 11
Appendix A (Normative) Test method of brightness response characteristics 14
Appendix B (Normative) Test method of signal-to-noise ratio ... 19
Appendix C (Normative) Test method of spatial frequency response ... 23
Appendix D (Normative) Test method of static image tolerance ... 29
Medical endoscopes - Video endoscopes
1 Scope
This standard specifies the terms and definitions, requirements, test methods
for medical video endoscopes.
This standard applies to medical video endoscopes (hereinafter referred to as
video endoscopes) for visible spectrum imaging in endoscopy and surgery.
This standard does not apply to medical video endoscopes for special spectral
and non-visible spectral imaging.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB 9706.19 Medical electrical equipment - Part 2: Particular requirements
for the safety of endoscopic equipment
GB/T 14233.1-2008 Test methods for infusion transfusion injection
equipment for medical use - Part 1: Chemical analysis methods
GB/T 16886.1 Biological evaluation of medical devices - Part 1: Evaluation
and testing
YY 0068.1-2008 Medical endoscopes - Rigid endoscope - Part 1: Optical
properties and test methods
YY 0068.2 Medical endoscopes - Rigid endoscope - Part 2: Mechanical
properties and test methods
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Conversion function
Where:
S - Output signal;
N - The root mean square of the noise signal.
3.4
Saturation value
The output signal value which further increases the brightness of the object
while the output signal remains constant.
3.5
Static image tolerance
The ratio of the maximum brightness of the critical object plane to the
minimum brightness of the critical object plane that the video endoscope can
distinguish in a single exposure.
3.6
Spatial frequency response; SFR
In a video endoscope, the function relationship between the ratio of the
modulation of the output signal which is subjected to the calculated value of
the reverse function of OECF to the modulation of the brightness of the
object plane of the target, and the spatial frequency of the target.
3.7
Sine-based spatial frequency response; s-SFR
The SFR when the target is a sine-wave modulation map.
3.8
Modulation transfer function
The ratio of the maximum signal value minus the minimum signal value to
the maximum signal value plus the minimum signal value.
3.9
Spectral neutral
portion shall be consistent with the internal material. If it is necessary to coat
the surface, the manufacturer shall provide the corresponding coating
requirements and test methods.
4.1.2 Requirements for chemical composition
4.1.2.1 General
The material used in the part in contact with the patient shall be clearly indicated
in any form possible by the manufacturer.
The metal material shall be marked by the designation and/or code as well as
the chemical composition requirements of the material; and be verified by test.
The Chinese and English abbreviations for non-metallic materials shall be
clearly indicated in any possible form.
4.1.2.2 Requirements for dissolved precipitate
The dissolved precipitates of the polymer material in contact with the patient
are as follows:
a) pH: As compared with the same batch of blank control solution, the
difference in pH shall be not more than 2.0;
b) Total content of soluble heavy metals: The total content of soluble heavy
metals in the eluate does not exceed 5.0 μg/mL;
c) Potassium permanganate reducing substance: The difference between
consumption of the same batch of blank control solution of equivalent
volume shall be not more than 2.0 mL.
4.1.3 Biocompatibility
Materials in contact with patients shall be evaluated for biosafety according to
the principles and requirements of GB/T 16886.1, to demonstrate good
biocompatibility.
The biological evaluation may consider the results of biological tests, wherein
the selection of the test items is carried out according to the guidelines of GB/T
16886.1.
For materials that have previously been proven to be applicable, if it can prove
that the subsequent manufacturing process is not sufficient to create a biosafety
hazard, it may not repeat the biological test.
Note 1: If the material of the device under design has an arguable history of use
in a specific application; or otherwise if the information about the
well as the corresponding camera mode (if the video endoscope has multiple
camera modes).
The tolerance of the signal-to-noise ratio is -20%. The upper limit is not counted.
4.6 Spatial frequency response
The manufacturer shall, in the accompanied data, give the nominal value of the
angular frequency of the object space of the video endoscope corresponding to
the SFR value of 50% and 30%, as well as the corresponding camera mode (if
the video endoscope has multiple camera modes).
The tolerance of the angular frequency of the object space corresponding to
the SFR value of 50% and 30% is -20%. The upper limit is not counted.
4.7 Static image tolerance
The manufacturer shall, in the accompanied data, give the nominal value of the
static image tolerance of the video endoscope as well as the corresponding
camera mode (if the video endoscope has multiple camera modes).
The tolerance of the static image tolerance is -20%. The upper limit is not
counted.
4.8 Mechanical properties
The mechanical properties of rigid video endoscopes shall comply with the
requirements of YY 0068.2.
4.9 Electrical safety
It shall meet the requirements of GB 9706.19.
5 Test methods
5.1 Test of material requirements
5.1.1 Surface material
Visual inspection. For products with a surface coating, follow the appropriate
test methods as provided by the manufacturer.
5.1.2 Test of chemical composition
5.1.2.1 General
Use the method which has an accuracy of better than or reaching to the
tolerance or 1/3 of the limit value to carry out the test of the chemical
When testing on the plane perpendicular to the axis, use the illuminometer to
measure the illuminance at the center of the filed angle. Record it as E0.
Calculate the arithmetic mean of the above four azimuth illuminances E1, E2,
E3, E4, as well as the ratio of the arithmetic mean value to the measured value
of the illuminance at the center of the field angle.
The calculated ratio shall be divided by the relative effect of lambert edge light
luminosity [see formula (2)], where w is the field angle corresponding to the
position where 0.9wp intersects the field angle.
Wp may be replaced by w.
5.4 Test method of brightness response characteristics
Check the technical data as provided by the manufacturer.
Use the method as specified in Appendix A to measure the brightness response
characteristics of the video endoscope.
5.5 Test method of signal-to-noise ratio
Check the technical data as provided by the manufacturer.
Use the method as specified in Appendix B to measure the signal-to-noise ratio
of the video endoscope.
5.6 Test method of spatial frequency response
Check the contents of the accompanied data as provided by the manufacturer.
Use the method as specified in Appendix C to measure the spatial frequency
response of the video endoscope.
5.7 Test method of static image tolerance
Check the contents of the accompanied data as provided by the manufacturer.
Use the method as specified in Appendix D to measure the static image
tolerance of the video endoscope.
5.8 Mechanical properties
The mechanical properties of the rigid video endoscope shall be carried out
according to the test methods as specified in YY 0068.2.
5.9 Electrical safety
It shall be carried out according to the test method as specified in GB 9706.19.
A.2 Steps
A.2.1 Test conditions
The temperature of the test environment is 23 °C ± 2 °C; the relative humidity
is 50% ± 20%.
The dark illuminance of the test environment is not more than 1 lx.
The power supply voltage’s stability of the control light source shall be
controlled within ±2%.
The light source shall be fully preheated and stable.
A.2.2 Test procedure
A.2.2.1 White balance
For the video endoscope which has the white balance function, use the test
target of A.1.1 to carry out white balance under the test conditions.
A.2.2.2 Viewing of video endoscope
Adjust the camera distance to the desired position. Record it as the measuring
working distance d0.
A.2.2.3 Focusing
If the video endoscope has an autofocus function, when shooting the tested
target, it may slightly blur the focusing, to reduce the noise as generated by the
texture of the block itself. The emphasis here is “slightly”. The boundaries
between blocks must be kept distinct.
A.2.2.4 Setting the brightness of background B on the test target
Adjust the brightness of the background B on the test target, to achieve the
brightness value L0 as specified by the manufacturer. During the whole course
of brightness change of the small gray-scale block A, the brightness of the
background B shall keep the overall gain of the tested video endoscope
unchanged.
A.2.2.5 Changing the brightness of the small gray-scale block A on the
test target and collecting the analysis image
Gradually change the brightness of the small gray-scale block A on the test
target. Within the tolerance range, select not less than 10 different brightness
levels which are basic in uniform distribution. Corresponding to each brightness
level, measure the brightness value and record it as Li. Use the video
endoscope to photograph the test target. Use the image collector to collect n
images and store it, wherein n is not less than 8.
For the collected image, select (M × N) pixels in the small gray-scale block-A
area (recommended 32 × 32). Respectively read the output signals of the output
signal matrix (M x N x 3) corresponding to each channel of red, green, blue of
each image.
For a certain brightness level Li, the average values , , of the signal
of each channel of red, green, blue are calculated from the arithmetic mean of
the R, G, B values of (M × N × n) pixels, respectively.
A.2.2.6 Calculating the display brightness value and fitness
For the obtained Li, corresponding to the , , data sets, use the elec-
opto conversion function (reverse function of OECF) of the output brightness
as given by the manufacturer to calculate the displayed brightness Lyi (yi
represents , , , respectively). If the manufacturer gives a data list, the
elec-opto conversion function of the output brightness may be obtained by the
use of piecewise linear fitting. The result of Lyi corresponding to the brightness
Li of each gray-scale of the actually measured target shall be represented in
the form of Table and/or graph.
Calculate the linear fit R2 of L - Ly (effective digits to 2 digits after the decimal
point). The calculation formula is as shown in formula (A.1):
Where:
m - The number of gray-scales;
- The average value of Li;
- The average value of Lyi.
The red, green, blue channels shall be calculated respectively.
A.3 Expression of results
Appendix B
(Normative)
Test method of signal-to-noise ratio
B.1 Equipment
B.1.1 Test target
Same as A.1.1.
B.1.2 Light source
Same as A.1.2.
B.1.3 Image collector
Same as A.1.4.
B.2 Steps
B.2.1 Test conditions
Same as A.2.1.
B.2.2 Test procedure
B.2.2.1 White balance
Same as A.2.2.1.
B.2.2.2 Viewing of video endoscope
Same as A.2.2.2.
B.2.2.3 Focusing
Same as A.2.2.3.
B.2.2.4 Setting the brightness of background B on the test target
Same as A.2.2.4.
B.2.2.5 Changing the brightness of the small gray-scale block A on the
test target and collecting the analysis image
Gradually change the brightness of the small gray-scale block A on the test
target. Within the tolerance range, select not less than 10 different brightness
levels which are basic in uniform distribution. Corresponding to each brightness
level, use the video endoscope to photograph the test target. Use the image
collector to collect n images and store it, wherein n is not less than 8.
For the collected image, select (M × N) pixels in the small gray-scale block-A
area (recommended 32 × 32). Respectively read the output signals of the output
signal matrix (M x N x 3) corresponding to each channel of red, green, blue of
each image.
B.2.2.6 Calculating the brightness signal component based on the output
signal of each channel of red, green, blue
For a certain brightness level, the average brightness signal component is
calculated from the arithmetic mean of the Y values of (M × N × n) pixels, where
Y is obtained by weighting the output signals of each channel of red, green,
blue. The weight of each channel is valued according to the coding method as
given by the manufacturer.
Note: The general standard code may be found in ISO 22028-1:2004.
Example: If the coding method uses the method as specified in ITU-R BT.709,
the calculation of Y value may be weighted as follows:
Where:
R, G, B - The output signal values of each channel of red, green, blue.
B.2.2.7 Calculating noise (represented by standard deviation)
According to the Y value obtained in B.2.2.6, calculate the output signal values
of the color difference channels (R - Y) and (B - Y).
The noise may be calculated based on the standard deviation of brightness
component σ (Y), the standard deviation of color difference channel σ (R - Y),
and σ (B - Y) according to the formula (B.2).
Where:
σ (Y) - The standard deviation of the brightness signal component Y;
σ (R - Y) - The standard deviation of the brightness channel lack of red;
σ (B - Y) - The standard deviation of the brightness channel lack of blue.
the spectral distribution curve’s shape of the light source is similar to the
spectral distribution curve’s shape as specified by the manufacturer. The
allowable difference of color temperature tolerance is ±10%.
If the manufacturer uses the light source which is provided by itself as the test
light source, the model and characteristics of the light source shall be declared
in the test report.
C.1.3 Image collector
Same as A.1.4.
C.2 Steps
C.2.1 Conditions of measurement
The illumination condition of the measured target is that the brightness of the
measured target shall cause the video endoscope to produce an acceptable
output signal level, but not over-exposed.
C.2.2 Test procedure
C.2.2.1 White balance
Same as A.2.2.1.
C.2.2.2 Viewing of video endoscope
Adjust the photographing distance to the desired position. Record it as the
measurement working distance d0. Center the test target.
C.2.2.3 Focusing of video endoscope
If the video endoscope has an autofocus function, it shall use the video
endoscope's autofocus system to focus on the measurement working distance
d0. In case of manual focus, select the sharpest focus setting when the spatial
frequency is about 1/4 of video endoscope’s Nyquist frequency.
C.2.2.4 Setting of video endoscope
The image compression function of the video endoscope may significantly
affect the measurement of resolution. For some video endoscopes, it may
select whether to enable the image compression function by pressing a button.
All settings of the video endoscope which may affect the measurement results,
including the shooting mode, test distance, etc., shall be reported together with
the measurement results.
C.2.2.5 Collecting images
D.2.2.5 Changing the brightness of the small gray-scale block A on the
test target and collecting the analysis image
The range of change of brightness level of the small gray-scale block A on the
test target shall be more than the tolerance range. Meanwhile at least 5
brightness levels are lower than the cut-off critical brightness value of the dark
area of the video endoscope to be tested. Near the cut-off critical brightness of
the dark area and the saturated critical brightness of bright area, the ratio of
adjacent brightness levels shall be not more than 1.1 times.
Gradually change the brightness of the small gray-scale block A on the test
target. For each selected brightness level, measure and record the brightness
value Li. Use the video endoscope to photograph the test target of the
corresponding brightness. Use the image collector to collect and save n images,
wherein n is not less than 8.
For the collected image, select (M × N) pixels in the small gray-scale block-A
area (recommended 32 × 32). Respectively read the output signals of the
corresponding output signal (M × N × 3) matrix corresponding to each channel
of red, green, blue in each image.
D.2.2.6 Calculating the brightness signal component based on the output
signal values of each channel of red, green, blue
Same as B.2.2.6.
D.2.2.7 Drawing the curve of brightness and the output value of
corresponding brightness signal
According to Li and as obtained in steps D.2.2.5 and D.2.2.6A, draw the
curve of the brightness and the corresponding brightness signal component.
D.2.2.8 Reading the brightness saturation threshold Lsat in highlight
region
Read the critical brightness value Lsat when the brightness signal component
in the highlight region on the curve is close to the saturation value.
Note: Any channel that reaches saturation is saturated.
D.2.2.9 Calculating the brightness cutoff threshold Lmin in dark area
Read the critical brightness Lmin when the brightness signal component in
the dark area starts cutting off from the curve.
Determination of the cutoff state: Use the average value of the brightness signal
component corresponding to the 5 sets of lower brightness levels as
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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