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YY/T 0794-2010 PDF in English

YY/T 0794-2010 (YY/T0794-2010, YYT 0794-2010, YYT0794-2010)
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YY/T 0794-2010: PDF in English (YYT 0794-2010)

YY/T 0794-2010
ICS 11.040.50
C 43
Particular specifications for computed radiography
Issued by: China Food and Drug Administration
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 4 
4 Composition ... 6 
5 Requirements ... 6 
6 Test method ... 9 
Appendix A (Informative) Comprehensive test scale ... 14 
Appendix B (Informative) Threshold contrast test phantom ... 16 
Appendix C (Informative) Justification ... 28 
Particular specifications for computed radiography
1 Scope
This standard specifies the terms and definitions, composition, requirements,
test methods of computed radiography device (hereinafter referred to as CR).
This standard applies to CR. The device uses an image plate that forms a
"latent image" after X-ray irradiation; forms a digital X-ray image by scanning
the "latent image" on the image plate. CR is used to obtain digital diagnostic
images after X-ray device photography, excluding X-ray photography device.
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 4793.1-2007 Safety requirements for electrical equipment for
measurement, control, and laboratory use - Part 1: General requirements
GB 7247.1-2001 Safety of laser products - Part 1: Equipment classification,
requirements and users guide
YY/T 0291-2007 Environmental requirements and test methods for medical
x-ray equipment
YY/T 0796-2010 Medical electrical device - Exposure index of digital X-ray
imaging system - Part 1: Definition and requirements of general X-ray
DICOM 3.0 Medical digital imaging and communication standard (third
IEC 60788 Medical electrical device - Glossary of terms and definitions
3 Terms and definitions
The terms and definitions as defined in IEC 60788 as well as the following terms
and definitions apply to this document.
It is a phenomenon that the potential image information of X-ray photography
recorded by the IP plate decreases with time before being read.
4 Composition
CR is mainly composed of imaging plate, scanning device, control processing
5 Requirements
5.1 Working conditions
5.1.1 Environmental conditions
Unless otherwise specified in the product standard, the working environment
conditions of CR shall meet:
a) Ambient temperature: 10 °C ~ 40 °C;
b) Relative humidity: 30% ~ 75%;
c) Atmospheric pressure: 700 hPa ~ 1060 hPa.
5.1.2 Power supply conditions
The working power supply conditions of CR shall meet:
a) For the power supply voltage and the number of phases specified in the
product standard, the fluctuation of the grid voltage shall not exceed ±10%
of the nominal value;
b) Power frequency: 50 Hz ± 1 Hz (products for export are specified by the
c) The power capacity as specified by the product standard.
5.2 Effective imaging area
The product standard shall specify the maximum size and deviation of the
effective imaging area of the IP plate in the X and Y directions; the deviation
shall not exceed ±5% of the nominal value.
5.3 Bit-depth
The product standard shall specify the bit-depth when the image is acquired; it
shall not be less than 12 bits/pixel.
Observe the exposed image of the specified test scale; there shall be no
geometric distortion of image.
5.12 Security of management information
There shall be software measures taken to ensure the privacy and reliability of
patient data.
5.13 Information management
There shall be software measures to manage patient information, at least with
the functions of registration, modification, deletion, query, statistics, backup
5.14 Film printing
It has the function of transferring images to a film printer.
5.15 Medical digital imaging and communication standards
If it conforms to the DICOM 3.0 standard or other network communication
standards, it shall provide a compliance statement in the accompanying
5.16 Noise
The noise generated during operation under working conditions shall not
exceed 70 dB (A weighting network) (not including non-continuous and non-
periodic noise within 3 s).
5.17 Appearance
The appearance shall be neat and beautiful; the surface shall be smooth and
clean; color shall be uniform. There shall be no defects such as scars, cracks,
5.18 Environmental test
It shall meet the requirements of YY/T 0291-2007 (except IP plate). In the initial,
intermediate or final testing, the device shall be able to be used normally without
abnormal phenomena.
5.19 Safety
It shall meet the requirements of GB 4793.1-2007 and GB 7247.1-2001.
The test steps are as follows:
a) Select appropriate loading conditions, so that the X-ray irradiation field
covers the entire IP plate;
b) Under the conditions of the effective imaging area, pixel size and bit-depth
of the specified IP plate, measure the time from when the IP plate is placed
in the CR scanning device to the time when the image that can be used
for medical diagnosis is completely displayed on the display;
c) The effective imaging area, pixel size and bit-depth of the IP plate shall be
recorded together with the measurement results.
6.5 Number of IP plates processed per hour
The test steps are as follows:
a) Select five IP plates of the same specification;
b) Start timekeeping when the first IP plate is inserted into the card slot of
the CR scanning device, until the last IP plate is withdrawn from the CR.
The operation time shall be shortened as much as possible for the part of
the CR that requires manual operation;
c) Measure the total time required to complete the entire process of the IP
plate’s processing cycle for 5 consecutive times; calculate the number of
IP plates processed in 1 h; the result takes an integer.
6.6 Threshold contrast
Use the test method specified in the product standard for testing, or test
according to the following methods as recommended by this standard, the steps
are as follows:
a) Use the threshold contrast phantom in Appendix B and select appropriate
loading conditions, to obtain the clearest phantom image;
b) Refer to Appendix B, to obtain the reciprocal of the image quality value
through calculation;
c) Repeat steps a) ~ b) to measure 3 times; take the average value;
d) The measurement conditions, effective imaging area of the IP plate, pixel
size, bit-depth shall be recorded together with the results.
6.7 Spatial resolution
Load according to the loading conditions as specified in the product standard
or automatic exposure control; meanwhile adjust the brightness and contrast to
other similar test scales;
b) According to the loading conditions as specified in the product standard,
the X-ray’s irradiation field covers the entire IP plate; the reference axis
shall be perpendicular to the IP plate, to expose the IP plate;
c) Scan the image of the IP plate; make visual inspection; there is no obvious
geometric distortion.
6.12 Security of management information
Verify by checking the device.
6.13 Information management
Verify by checking the device.
6.14 Film printing
Verify by inspection.
6.15 Medical digital imaging and communication standards
Verify by checking its declaration of conformity.
6.16 Noise
The sound level meter’s probe is 1 m away from the surface of the CR system
and 1.5 m from the floor. The sound level meter "A" class weighting network is
used for measurement; use the maximum noise value for calculation.
6.17 Appearance
Observe visually.
6.18 Environmental test
It is performed according to the requirements of YY/T 0291-2007.
6.19 Security
The inspection shall be carried out according to the requirements of GB 4793.1-
2007 and GB 7247.1-2001.
Appendix C
C.1 Description about 3.1, 3.2, 3.3
Photostimulable Luminescence (PSL) is the basis of CR imaging. This feature
makes CR different from other medical imaging device.
The imaging layer in the IP plate is a layer of barium halide fluoride crystals
containing divalent europium ions. The compound in the crystal layer is
irradiated by X-rays; the fluorescent substance absorbs the incident X-rays and
stores its energy, forming a latent image and storing it in the crystal, which is a
simulated image (this is the first excitation); then the laser beam scans the
fluorescent screen with latent image (second excitation); the information stored
on the screen is radiated from the converted light signal. The wavelength of the
helium-neon laser beam used is 670 nm ~ 690 nm. The surface of the IP plate
is scanned sequentially in the direction perpendicular to the IP plate. The
phosphor refracted from the IP plate is excited by the secondary excitation
(called Photostimulable Luminescence, PSL), producing fluorescence. The
intensity of the fluorescence is precisely proportional to the latent image energy
at the first excitation. The fluorescence is collected and guided along the high-
efficiency light guide filmed by laser scanning; enters the photomultiplier tube;
is amplified by the A/D converter into a digital signal and stored on the computer.
The computer can further process the stored images and display them. The
signal on the storage screen can be erased by strong light for the next use.
CR does not include X-ray machines. Its main purpose is to replace the
traditional X-ray screen-film system, to realize the digital processing and
storage of diagnostic images.
C.2 Description of 3.4 and 3.5
For the specifications of the IP plate, its effective imaging area, bit-depth, pixel
size determines the image quality of X-ray digital images from the hardware.
C.3 Descriptions of 5.6
Image quality figure (IQF) is a method of quantifying images for threshold
contrast evaluation. The following methods can be used for threshold contrast
a) Draw a curve that passes through the threshold area, which is called the
contrast-detail curve.
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.