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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This standard was proposed by the National Medical Products Administration.
This standard is under the jurisdiction of National Technical Subcommittee on Medical Optics and Instruments of Standardization Administration of China (SAC/TC 103/SC 1).
Medical endoscopes — Video endoscopes
1 Scope
This standard specifies the terms and definitions, requirements, test methods for medical video endoscopes.
This standard is applicable to medical video endoscopes (hereinafter referred to as video endoscopes) for visible spectrum imaging in endoscopy and surgery.
This standard is not applicable to medical video endoscopes with special spectral effects and non-visible spectrum imaging.
2 Normative references
The following referenced document is indispensable for the application of this standard. For dated reference, only the edition cited applies. For undated references, the latest edition of the referenced documents (including any amendments) applies.
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 equipments for medical use — Part 1: Chemical analysis methods
GB/T 16886.1 Biological evaluation of medical devices — Part 1: Evaluation and testing within a risk management process
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
For the purposes of this document, the following terms and definitions apply.
3.1
conversion function
transformation relations between different variables
?
3.1.1
opto-electronic conversion function; OECF
ideal relations between object luminance of video endoscope and corresponding output signal
3.1.2
elec-opto conversion function
OECF inverse function
3.2
noise
disturbances internally generated in the response signal of video endoscope
3.2.1
total noise
superposition of fixed pattern noise and temporally varying noise
3.2.2
fixed pattern noise
difference of output signals between area sensor units
3.2.3
temporally varying noise
difference of output signal between multiple exposures of a unit of area sensor
3.3
signal-to-noise ratio
at a specific signal level, the ratio of the output signal to the root mean square value (rms) of the noise signal is expressed as a logarithm; the expressions are shown in Equation (1):
SNR=20 lg?(S/N) (1)
where,
S——the output signal;
N——the root mean square value of noise signal.
3.4
saturation value
output signal value of which the object luminance is further increased and the output signal remains constant
3.5
static image tolerance
ratio of the maximum critical object luminance and the minimum critical object luminance that may be resolved by a video endoscope in single exposure
3.6
spatial frequency response; SFR
ratio of the modulation transfer function of the output signal calculated by the inverse number of OECF to the modulation transfer function of the object luminance of the target in an electronic endoscope; functional relationship between spatial frequencies of target
3.7
sine-based spatial frequency response; s-SFR
SFR when the target is a sine modulation diagram
3.8
modulation transfer function
ratio between the maximum signal value minus the minimum signal value and the maximum signal value plus the minimum signal value
3.9
spectrally neutral
reflection or transmission characteristics of a certain wavelength band remain unchanged
3.10
relative effect of Lambert edge light luminosity; LLe-z or LL_(e-z)^'
edge light effect of Lambert radiator on the illuminated body when the plane element radiates opposite to the inner sphere, as shown in Figure 1; see Equation (2) and Equation (3)
when the end of the optical scope radiates to the sphere Z:
{█(&LL_(e-z)=((sin?w-sin?ε)/(sin?( w-ε)))^2 cos?w?cos?ε@&sin?ε=z/(1+z) sin?w )┤ (2)
when the sphere Z radiates the entrance pupil of optical scope:
{█(&LL_(e-z)^'=((sin?〖w_p 〗-sin?θ)/(sin?( w_p-θ)))^2 cos?〖w_p 〗?cos?θ@&sin?θ=(z-a/d)/(1+z) sin?〖w_p 〗 )┤ (3)
Note 1: See YY 0068.1-2008 for the description of w, wp and Z in the equation.
Note 2: The plane perpendicular to the visual axis is a special case of sphere Z. Z = ∞ means that the sphere Z overlaps with the plane perpendicular to the visual axis, and the Lambert body light efficiency expression is:
LLe-∞=cos4w or LL_(e-∞)^'=〖cos〗^4?〖w_p 〗
Keys:
1——the inner sphere;
2——the plane element;
3——the center of the inner sphere.
Figure 1 Schematic diagram of relative effect of Lambert edge light luminosity
3.11
relative self-effect of illumination light luminosity; ILeR
under the condition of cosine radiator illuminating close to the surface, the contribution of optical path of optical scope illumination to edge light effect takes luminance as luminosity the expressions are shown in Equation (4):
IL_eR=L_w/L_0 (4)
where,
Lw——the average luminance in the direction of view angle w;
L0——the luminance in the center direction of the field of view.
4 Requirements
4.1 Materials used in contact with patients
4.1.1 Materials on metal surface
If the material in contact with the patient is metal, the exposed part shall be consistent with the internal material. If it does need to coat the surface, the manufacturer shall provide corresponding coating requirements and test methods.
4.1.2 Requirements of chemical composition
4.1.2.1 General
The materials used in contact with patients shall be clearly indicated by the manufacturer in any possible way.
The metal materials shall be marked with the designation and/or code and the chemical composition requirements of the materials, which shall be verified by tests.
Abbreviations for non-metallic materials in both Chinese and English shall be clearly indicated in any possible way.
4.1.2.2 Requirements for dissolved precipitates
The requirements for dissolved precipitates of polymer materials in contact with patients are as follows:
a) pH: compared with the blank control solution of the same batch, the pH difference shall not be greater than 2.0;
b) Total soluble heavy metal content: the total soluble heavy metal content in the dissolution liquid shall not exceed 5.0 μ g/ml;
c) Reducing substance of potassium permanganate: the consumption difference between reducing substance of potassium permanganate and the same batch of blank control solution with the same volume shall be no more than 2.0 mL.
4.1.3 Biocompatibility
Materials in contact with patients shall be evaluated for biological safety according to the principles and requirements of GB/T 16886.1 to prove its good biocompatibility.
Biological evaluation may take the results of biological tests into account, and the selection of test items shall be conducted according to the guidelines of GB/T 16886.1.
For materials that have been proved to be applicable before, if it can be proved that the subsequent process of their manufacture is not enough to produce biosafety hazards, biological tests may not be repeated.
Note 1: The materials of the devices in the design have a demonstrable history of use in specific applications, or information about the materials and/or devices may be obtained from other aspects, so it may be considered that the materials have been proved to be applicable before.
Note 2: If the metal material adopts the medical metal material with applicable application range in national or industrial standards, the biological test may not be repeated.
4.2 Field of view
It shall meet the requirements of field of view in 4.2.1 of YY 0068.1-2008.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Requirements
5 Test method
Annex A (Normative) Test method of luminance response characteristics
Annex B (Normative) Test method of signal-to-noise ratio
Annex C (Normative) Test method of spatial frequency response
Annex D (Normative) Test method of static image tolerance
