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YY/T 0933-2022 (YY/T0933-2022)

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YY/T 0933-2022: PDF in English (YYT 0933-2022)

YY/T 0933-2022
YY
PHARMACEUTICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 11.040.50
CCS C 43
Replacing YY/T 0933-2014
Digital Medical X-ray Image Detector Used in General
Radiography
ISSUED ON: MAY 18, 2022
IMPLEMENTED ON: JUNE 1, 2023
Issued by: National Medical Products Administration
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative References ... 6
3 Terms and Definitions ... 6
4 Classification and Composition ... 7
5 Requirements ... 8
6 Test Methods ... 10
Appendix A (normative) Test Layout ... 17
Appendix B (informative) Test Device ... 19
Digital Medical X-ray Image Detector Used in General
Radiography
1 Scope
This document specifies the terms and definitions, classification and composition, requirements
and test methods for digital medical X-ray image detector used in general radiography
(hereinafter referred to as the detector).
This document is applicable to detectors with the single-exposure imaging function, which
include, but are not limited to: amorphous silicon detectors, amorphous selenium detectors,
CCD detectors and CMOS detectors, etc.
This document does not apply to detectors for mammography and detectors for dental
photography.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
GB/T 10149 Terminology and Symbol for Medical X-ray Equipment
YY/T 0063 Medical Electrical Equipment - X-ray Tube Assemblies for Medical Diagnosis -
Characteristics of Focal Spots
YY/T 0291 Environmental Requirements and Test Methods for Medical X-ray Equipment
YY/T 0481-2016 Medical Diagnostic X-ray Equipment - Radiation Conditions for Use in the
Determination of Characteristics
YY/T 0590.1-2018 Medical Electrical Equipment - Characteristics of Digital X-ray Imaging
Devices - Part 1: Determination of the Detective Quantum Efficiency - Detectors Used in
Radiographic Imaging
YY/T 0741 Particular Specifications for Digital X-ray Radiography System
3 Terms and Definitions
What is defined in GB/T 10149, YY/T 0063, YY/T 0481-2016, YY/T 0590.1-2018 and YY/T
0741, and the following terms and definitions are applicable to this document.
3.1 Calibration
Calibration refers to some processing, in which the detector completes necessary operations, so
that the image can satisfy the evaluation requirements, such as: background correction, gain
correction and bad pixel correction, etc. These processing are linear and irrelevant to the image.
3.2 Central Axis
Central axis refers to a straight line perpendicular to the incidence plane and passing through
the center of the entrance field.
3.3 Bright Image
Bright image refers to an original X-ray exposure image without the background correction,
gain correction and bad pixel correction.
3.4 Dark Image
Dark image refers to an original unexposed image without the background correction, gain
correction and bad pixel correction.
3.5 Noise Equivalent Dose
Noise equivalent dose refers to the corresponding dose when the quantum noise and the system
noise are equivalent.
NOTE: quantum noise is the random fluctuation of X-photons absorbed by the detector; system
noise is the inherent fluctuation of the detector system that deviates from the expected
value of the stochastic process.
3.6 Linear Dynamic Range
Linear dynamic range refers to the range of X-ray incident dose changes that can be linearly
detected by the detector. The minimum value and maximum value of this range are respectively
represented by the noise equivalent dose and the maximum linear dose. The coefficient of
determination (i.e., the squared value of the correlation coefficient r) is used to represent the
gray value and linear dose degree.
4 Classification and Composition
4.1 Classification
The classification is performed in accordance with the structural characteristics and data
transmission mode of the product:
a) In accordance with the structural characteristics: portable detectors and fixed
detectors;
5.5.1 Noise Equivalent Dose
The manufacturer shall specify the noise equivalent dose under the specified gain, and within
the shooting dose range of the noise equivalent dose image, the coefficient of determination R2
of the variance of the detector’s output gray value and the dose shall be greater than 0.98.
5.5.2 Linear dynamic range
The manufacturer shall specify the linear dynamic range under the specified gain, and within
the range, the coefficient of determination R2 of the detector’s output gray value and the dose
shall be greater than 0.98.
5.5.3 Spatial resolution
The manufacturer shall specify the spatial resolution of the detector without attenuation.
5.5.4 Modulation transfer function
The manufacturer shall specify the modulation transfer function value at the specified spatial
frequency (at least 0.5 lp/mm, 1.0 lp/mm, 1.5 lp/mm, until slightly lower than the Nyquist
frequency). The measurement result of the modulation transfer function shall comply with the
manufacturer’s stipulations.
5.5.5 Quantum detection efficiency
The manufacturer shall specify the quantum detection efficiency value of the detector at the
specified spatial frequency (at least 0.5 lp/mm, 1.0 lp/mm, 1.5 lp/mm, until slightly lower than
the Nyquist frequency). The measurement result of the quantum detection efficiency shall
comply with the manufacturer’s stipulations.
5.5.6 Image uniformity
The manufacturer shall specify that under the recommended SID and loading factors, in images
of different doses, for the ratio of the standard deviation S of the gray value of the sampling
point to the mean value Vm of the gray value, the maximum value Um shall not be greater than
2.5%.
5.5.7 Afterimage
The afterimage shall not be greater than 0.5%.
5.5.8 Artifact
There shall be no visible artifacts.
5.6 Mechanical Strength
5.6.1 Falling
Under normal working conditions, when the portable detector freely falls on a hard surface at
the height specified by the manufacturer, it shall be able to normally work. The determination
items shall at least include 5.5.3 and 5.5.6.
5.6.2 Bearing
The portable detectors shall be able to normally work when bearing a uniform load of 135 kg
or the target load declared by the manufacturer; the portable detectors shall be able to normally
work when bearing a partial load declared by the manufacturer. The determination items shall
at least include 5.5.3 and 5.5.6.
5.7 Communication
When the detectors are equipped with the function of wireless transmission, the accompanying
documents shall at least announce the requirements for frequency range, radio output power,
communication protocol, storage format and user access control.
5.8 Appearance
The appearance of the detectors shall comply with the following requirements:
a) The shape shall be neat, the surface shall be smooth and clean, the color shall be
uniform, and there shall be no defects like scars or cracks;
b) The surface of the detector shall be marked with the center and boundary of the
effective photographic area;
c) The labels and marks shall be clearly visible;
d) The electrical interface shall be free of corrosion, and shall have clear interface
definition marks;
e) The mechanical installation shall be correct and firm, and the control parts shall not
be loose or fall off, and the use shall be reliable;
f) The structural parts shall be firmly fastened without looseness.
5.9 Environmental Test
Unless it is otherwise specified, the product shall comply with the requirements of YY/T 0291.
The intermediate or final inspection items shall at least include the requirements of 5.2 and
5.5.3.
6 Test Methods
6.1 Test Conditions
6.1.1 Environmental conditions
b) Under the service conditions declared by the manufacturer, expose to acquire the
bright image.
c) In the image generated by exposure, respectively read the scale data x2 and x3 on the
image at the two ends of the lead scale. In accordance with Formula (1) and Formula
(2), calculate the ratio of the effective imaging area to the specified effective size:
Where,
x1---the size declared by the manufacturer.
d) In another direction perpendicular to the current test method, repeat steps a) ~ c) to
obtain dy.
e) The minimum value of dx and dy shall comply with the requirements; the conversion
method can be adopted when the lead scale cannot approach the surface of the detector.
6.5 Image Quality
6.5.1 Noise equivalent dose
The test layout is shown in Figure A.1 in Appendix A. Unless it is otherwise specified, the
distance from the focal point to the surface of the detector shall be 1.5 m. The X-ray field
completely covers the detector surface; the central axis of the X-ray field is consistent with the
center of the detector surface and perpendicular to the detector surface.
a) Take the RQA5 standard radiation quality specified in Chapter 6 of YY/T 0481-2016
and the dose or gray value defined by the manufacturer as the calibration conditions
to complete the calibration described in 6.1.3;
b) Collect a calibrated dark image;
c) Maintain the tube voltage defined by the RQA5 radiation quality, within the range of
the noise equivalent dose value declared by the detector manufacturer, collect 4
calibrated exposure images, and record the dose value at the center of the detector
surface corresponding to each image. At the center of the image collected in Step b)
and Step c), select a sampling area of 64  64 pixels and calculate the variance of the
sampling area. Perform linear fitting on the obtained 5 groups of dose values and the
corresponding variance. In accordance with Formula (3), calculate the noise
equivalent dose and calculate the coefficient of determination R2:
Where,
b---the intercept of the dose - variance curve and the Y axis, that is, the variance of
the image collected in Step b);
K---the slope of the dose - variance curve.
6.5.2 Linear dynamic range
The test layout is shown in Figure A.1 in Appendix A. Unless it is otherwise specified, the
distance from the focal point to the surface of the detector shall be 1.5 m. The X-ray field
completely covers the detector surface; the central axis of the X-ray field is consistent with the
center of the detector surface and perpendicular to the detector surface.
a) Use the RQA5 standard radiation quality specified in Chapter 6 of YY/T 0481-2016
to complete the calibration specified in 6.1.3. Within the gain and dose input range
specified by the manufacturer, uniformly select 5 test points (including the minimum
linear dose and the maximum linear dose; the minimum linear dose can be replaced
by the noise equivalent dose; if the maximum linear dose conditions cannot be
achieved, approach them as much as possible); obtain the corresponding five
calibrated bright images through exposure acquisition; measure the dose value at the
center of the detector surface for each exposure.
b) At the center of the image collected in Step a), select a sampling area of 64  64 pixels
and calculate the average gray value of the sampling area. Perform linear fitting on
the obtained 5 groups of dose values and the corresponding average gray value data,
and calculate the coefficient of determination R2.
c) The linear dynamic range is obtained through the noise equivalent dose and the
maximum linear dose value.
NOTE: the minimum linear dose can be replaced by NED. For the measurement of the
maximum linear dose, it can be approximated through the method of gradually
increasing the current-time product. If the current-time product step size is
excessively large, the SID method can be adjusted to approach the maximum linear
dose as much as possible.
6.5.3 Spatial resolution
The test layout is shown in Figure A.1. Remove 21 mm aluminum attenuation; at the dose or
gray value specified by the manufacturer, complete the calibration of the detector.
The test device adopts a line pair resolution test card, and the test card is 45 to the pixel matrix.
Under the calibration conditions, take the image and properly adjust the image to the optimum;
visually observe and record the spatial resolution value and the corresponding loading factor
combination.
6.5.7 Afterimage
The test layout and calculation method shall comply with the method specified in Appendix
A.3.3 “detection of proliferation hysteresis effect” in YY/T 0590.1-2018.
6.5.8 Artifact
The test procedures are as follows:
a) Take the RQA5 standard radiation quality specified in Chapter 6 of YY/T 0481-2016
and the dose or gray value defined by the manufacturer as the calibration conditions
to complete the calibration described in 6.1.3;
b) Expose at 20% and 80% of the maximum linear dose;
c) Properly adjust the window width and level; visually observe whether there are
artifacts in the generated image.
6.6 Mechanical Strength
6.6.1 Falling
Lift it to the height specified by the manufacturer and place it above a 50 mm  5 mm thick
hardwood (for example, hardwood > 600 kg/m3) board placed flat on a hard foundation
(concrete); let it freely fall once in each of 3 different initial states. After the falling test is over,
the detector shall be able to normally work.
6.6.2 Bearing
Horizontally place the detector on a hard foundation plane larger than its area; evenly distribute
a load of 135 kg or the target uniform load declared by the manufacturer on the surface of the
detector (as shown in Figure 1) for 1 min. During and after the test, the detector shall manifest
no permanent deformation and shall be able to normally work.
Figure 1 -- Schematic Diagram of Uniform Load on the Detector
......
 
(Above excerpt was released on 2023-03-01, modified on 2023-03-01, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/YYT0933-2022