ISO 20498-1:2019

INTERNATIONAL ISO
STANDARD 20498-1
First edition
2019-03
Corrected version
2019-05
Traditional Chinese medicine —
Computerized tongue image analysis
system —
Part 1:
General requirements
Médecine traditionnelle chinoise — Système d’analyse d’images
numérisées de la langue —
Partie 1: Exigences générales
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Components of CTIS . 2
5 Technical requirements . 2
5.1 General . 2
5.2 Tongue positioning . 2
5.3 Lighting part . 2
5.4 Image acquisition part . 3
5.4.1 General. 3
5.4.2 Spatial resolution . 3
5.4.3 Colour components . 3
5.4.4 Colour components acquirement . 4
5.5 Data processing part . 4
5.6 Display . 4
6 Safety . 4
6.1 Safety of material . 4
6.2 Prevention from infection . 4
6.3 General requirements for testing of ME equipment . 4
6.4 Electrical hazards . 5
6.5 Mechanical hazards . 5
Annex A (informative) Tongue positioning . 6
Annex B (informative) Test methods for CTIS . 7
Annex C (informative) Data processing part . 9
Bibliography .11
Foreword
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This document was prepared by Technical Committee ISO/TC 249, Traditional Chinese medicine.
A list of all parts in the ISO 20498 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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This corrected version of ISO 20498-1:2019 incorporates the following corrections:
— edition date in the running header changed to 2019;
— copyright date in the footer changed to 2019.
iv © ISO 2019 – All rights reserved

Introduction
The tongue’s colour, form, motion, substance and coating are the main factors to be considered when
analysing tongue features. Measuring the geometric shape involves observing the changes in the
thickness and size of a tongue and the cracks and teeth marks on its surface. The important features of
the tongue coating which cover the surface of the tongue are colour, degree of wetness, thickness, form
and distribution.
Although tongue diagnosis is convenient and non-invasive, it is difficult to achieve an objective and
standardized examination. Differences in inspection circumstances, such as light source or a client’s
posture, affect the result significantly. Moreover, as the diagnosis relies on the observer’s experience
and knowledge, it is hard to obtain a standardized result. Recently, many research projects have
attempted to solve these problems, and various types of computerized tongue image analysis system
(CTIS) have been developed.
Various cameras, such as a commercial digital camera, bayer charge-coupled device (CCD) camera,
high-performance 3CCD camera and a hyperspectral camera, were used for the CTIS. Recently, a multi-
view CTIS has been developed designed for 3D tongue modelling and sublingual vein acquirement,
comprising 3D CTIS.
Different CTIS technologies have unique advantages and specificities according to the application
and diagnostic environment, but this variation may cause inconsistent diagnoses in practical clinical
application. To improve CTIS performance and clinical approach, it has become necessary to develop an
International Standard for the functions and elements of a CTIS.
INTERNATIONAL STANDARD ISO 20498-1:2019(E)
Traditional Chinese medicine — Computerized tongue
image analysis system —
Part 1:
General requirements
1 Scope
This document specifies general requirements for a computerized tongue image analysis system (CTIS).
This document is limited to the safety aspects and technical requirements for a CTIS, excluding the
diagnosis or interpretation of tongue images.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements for this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 10993-1, Biological evaluation of medical devices — Part 1: Evaluation and testing within a risk
management process
ISO 20498-2, Traditional Chinese medicine — Computerized tongue image analysis system — Part 2: Light
environment
IEC 60601-1:2005/AMD1: 2012, Medical electrical equipment — Part 1: General requirements for basic
safety and essential performance
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
computerized tongue image analysis system
CTIS
device or system used to acquire tongue images to be analysed by computer
3.2
charge-coupled device
CCD
device for the movement of electrical charge, usually from within the device to an area where the
charge can be manipulated
3.3
tongue positioning
guiding and maintaining the posture of the protruding tongue
3.4
lighting part
structure for illuminating the tongue surface with various light sources and optical techniques
3.5
image acquisition part
image sensor and optical lenses used to produce the
...