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GB 17589-2011: Specifications for quality assurance test for computed tomography X-ray scanners
Status: Valid GB 17589: Evolution and historical versions
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Specifications for quality assurance test for computed tomography X-ray scanners
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GB 17589-2011
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| GB/T 17589-1998 | English | 319 |
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Specification of image quality assurance test for X-ray equipment for computed tomography
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Basic data | Standard ID | GB 17589-2011 (GB17589-2011) | | Description (Translated English) | Specifications for quality assurance test for computed tomography X-ray scanners | | Sector / Industry | National Standard | | Classification of Chinese Standard | C57 | | Classification of International Standard | 13.280 | | Word Count Estimation | 13,158 | | Date of Issue | 2011-12-30 | | Date of Implementation | 2012-05-01 | | Older Standard (superseded by this standard) | GB/T 17589-1998 | | Quoted Standard | GB/T 19042.5 | | Regulation (derived from) | Announcement of Newly Approved National Standards No. 23 of 2011 | | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China | | Summary | This Chinese standard specifies requirements for medical X-ray equipment for computed tomography (computed tomography X-ray scanner, referred CT) for the purpose of quality assurance testing methods and their projects and requirements. This standard applies to CT machine acceptance testing, the use of CT for detecting a state machine and stability testing. This standard does not apply to the production of CT and CT quality control as well as supporting the use of video display systems and hard copy system. | GB 17589-2011: Specifications for quality assurance test for computed tomography X-ray scanners---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Specifications for quality assurance test for computed tomography X-ray scanners
ICS 13.280
C57
National Standards of People's Republic of China
Replacing GB/T 17589-1998
X-ray computer tomography apparatus
Quality assurance testing standards
Issued on. 2011-12-30
2012-05-01 implementation
People's Republic of China Ministry of Health
Standardization Administration of China released
Foreword
This standard was drafted in accordance with GB/T 1.1-2009 given rules.
This standard replaces GB/T 17589-1998 "X-ray computed tomography apparatus of image quality assurance testing standards."
This standard compared with GB/T 17589-1998, the major technical changes as follows.
--- The GB/T 17589-1998 in Table 1 is amended as normative appendix;
--- Increasing the value of CT to detect a linear content;
--- Modify the definition and calculation of noise;
--- Modify the project name and the calculation method CTDI;
--- Modify the detection of high contrast resolution;
--- Modify the project name and test methods can detect low-contrast capability and reconstruction thickness deviation.
This standard is proposed and administered by the People's Republic of China Ministry of Health.
This standard by the People's Republic of China Ministry of Health is responsible for interpretation.
This standard was drafted. Chinese Center for Disease Control Radiation Protection and Nuclear Safety of the medicine.
The main drafters of this standard. Yuebao Rong, Wei Dao, Liu Lan Tao.
This standard replaces the standards previously issued as follows.
--- GB/T 17589-1998.
X-ray computer tomography apparatus
Quality assurance testing standards
1 Scope
This standard provides for medical X-ray computed tomography apparatus (computedtomographyX-rayscanner, Acronym
CT) for the purpose of quality assurance testing methods and projects and requirements.
This standard applies to acceptance testing CT machines, CT machines use state testing and stability testing. This standard does not apply to CT machine
Production quality control, and supporting the use of CT imaging and display system and hard copy system.
2 Normative references
The following documents for the application of this standard is essential. For dated references, only the dated version suitable for use herein
Member. For undated references, the latest edition (including any amendments) applies to this document.
Evaluation and routine testing - Part 3-5 GB/T 19042.5 medical imaging departments. X-ray computed tomography imaging apparatus
Performance Acceptance Test
3 Terms and Definitions
The following terms and definitions apply to this document.
3.1
CT dose index CTdoseindex, CTDI100
Standard cross section along the central axis from -50mm to 50mm to integral dose profile curve, divided by the nominal thickness with a single sweep
Product description generating N number of faults, according to equation (1) calculations.
CTDI100 = ∫
-50
D (z)
N × Tdz
(1)
Where.
T --- nominal thickness;
N --- Number of faults arising from a single scan;
D (z) --- standard dose cross section along the central axis of the profile curve.
Note. A scan consists of many levels.
3.2
Weighted CT dose index weightedCTdoseindex, CTDIw
The average value of the phantom center CTDI100 collected CTDI100 and peripheral points collected weighted sum.
CTDIw = 13CTDI100, c
3CTDI100, p
(2)
Where.
CTDI100, c --- phantom center collected CTDI100;
CTDI100, p --- motif peripheral points collected CTDI100 average.
3.3
CT value CTnumber
CT image voxel corresponding to each pixel of the X-ray attenuation average.
Note. CT Hounsfield value is usually used as a unit, referred to as HU. Using (3), the attenuation values measured in accordance with internationally harmonized turn Hounsfield scale
CT values replaced.
CT value substance substance = μ -μ water
μ water
× 1000 (3)
Where.
Linear attenuation coefficient μ substance --- ROIs substance.
Linear attenuation coefficient μ water --- water.
According to the above definition of CT value scale, then there must be. water CT value 0HU, air CT value -1000HU.
3.4
Voxel voxel
Is an imaging layer in artificial division, several small basic unit in a rectangular array.
3.5
Dose profile curve doseprofile
On a standard cross-sectional central axis dose distribution with the correlation function of its position.
3.6
The full width at half maximum fulwidthathalf-maximum
Half the maximum distance between two points on the dose profile curve.
3.7
High contrast resolution high-contrastresolution
Spatial resolution spatialresolution
In the object with the background on the difference in the degree of attenuation of noise sufficiently large as compared with the case where, CT imaging distinguish objects of different sizes
ability.
Note. In general, the attenuation coefficient difference between the object and the background of the result for the corresponding CT value difference 100HU above is considered to be large enough.
3.8
The average CT value meanCTnumber
The average of all the pixel values of CT in a special area of interest.
3.9
Noise noise
In homogeneous mass image, given its regional variation in the average value CT. Available in the size of the region of interest of a uniform substance CT
Divided by the standard deviation value of the contrast scale representation.
3.10
Nominal thickness nominaltomographyslicethickness
CT machine is selected on the control panel and indicating the layer thickness.
3.11
ROIs regionofinterest, ROI
Within a given time images of particular interest to the local area.
3.12
Sensitivity profile curve sensitivityprofile
As a function of position in the vertical correlation response volume CT system on a straight line fault plane.
3.13
Reconstruction thickness reconstructedslicethickness
The half-scan field at the center of a cross-sectional imaging sensitivity curve full width.
3.14
Pitch pitch
360 ° from the tube and the diagnostic bed with ratio of the total width of the imaging detector for each rotation.
P = dMS
(4)
Where.
d --- tube each 360 ° rotation diagnostic bed moving distance;
M --- tube each 360 ° rotation of the tomographic image of a number;
S --- each piece of tomographic images of the nominal thickness.
3.15
Uniformity uniformity
The entire scan field, the consistency of a homogeneous mass imaging CT values.
3.16
Baseline baselinevalue
Reference X-ray diagnostic equipment function parameters. After the acceptance or status is qualified, from the initial stability testing obtained
Value, or by the respective standard values given.
3.17
Low-contrast detectability ability lowcontrastdetectability
CT machine can identify the minimum size of the image low-contrast detail.
3.18
Acceptance Testing acceptancetest
X-ray diagnostic equipment after installation or major repairs, as identified compromising image quality performance indicators into compliance with the agreed value
Line testing.
3.19
State detection statustest
Detecting device for evaluating the state carried out, usually once a year to detect the state.
3.20
Stability testing constancytest
To determine the X-ray diagnostic imaging equipment or under given conditions for the formation of the initial state whether the change in relative control standards and still meet
In testing.
4 Detection
Positioning accuracy of 4.1 Diagnosis bed
4.1.1 minimum scale of 1mm, an effective length of 500mm near the straightedge diagnosis fixed bed of moving bed, and to ensure that the ruler
Parallel to the direction of movement of the bed and the bed surface can indicate as a ruler tick mark pointer.
4.1.2 ensure that the bed load of about 70kg.
4.1.3 were given the diagnosis of bed "into 300mm" and "back 300mm" instruction.
4.1.4 record forward, back the start and end point values shown on the ruler, measure the positioning error and homing error.
4.2 optical positioning accuracy
4.2.1 motif detection
4.2.1.1 detector module having a body with a surface clear alignment marks, embedded within the specific shape of the object, the shape of the object, the position of
Should mold surface alignment mark with strict spatial relations.
4.2.1.2 The detection module body is placed in the center line of the radiation field is fixed, the mold body axis perpendicular to the scanning cross section, so that all surfaces of the phantom trimming
Marking and locating light coincide.
4.2.1.3 the head of clinical common exposure conditions, the total thickness of less than 3mm imaging collimator axial scanning mode to obtain positioning light
Markable layer image, comparing the image with a standard shape and positional relationship between the level of a particular object are the same, if the same, then the alignment light,
accurate.
4.2.1.4 4.2.1.3 If the two do not match, the scan back and forth perpendicular to the axis of the level of fine-tuning die body in accordance with 4.2.1.3
Scanning conditions, ultimately consistent with the nominal level of the image, according to the mold body to adjust the distance along the axis, positioning light to determine the degree of deviation.
4.2.2 film detection
4.2.2.1 Select an unexposed film in a dark room with black paper wrapped tightly and keep it neat.
4.2.2.2 In the paper side of the direction perpendicular to the longitudinal direction draw two straight lines, a straight line distance of 10cm or more, respectively, with a needle through the two straight lines
2 and 3 holes, hole diameter should be as small as possible and should not exceed the maximum diameter of 1mm, hole spacing at least greater than 5cm.
4.2.2.3 The perforated with small holes on the film flat on the examining table, the film coincides with the central axis of rotation and CT center will first have to wear two
Linear positioned within the aperture of light projected on the film coincides with the CT machine positioning within the set mode, choose a lower exposure conditions, minimum
Nominal thickness, the use of single-axial scan mode to scan.
4.2.2.4 and then pan the film, will wear a straight line with three holes positioned outside the projection of light on the film coincides with the CT machine outside the given set
Bit mode, using the same exposure conditions 4.2.2.3 scan.
4.2.2.5 final rinse scanned film were measured inside, positioned between the outer light corresponding scanning line of the image on the film and the line in a spin
Turn on the central axis of the pitch, the pitch as an inner and outer locating the light of deviation.
4.3 gantry angle precision
4.3.1 center with a clear mark of rectangular motifs, the phantom center coincides with the center of the fault wild, and the level fixed, according to
4.2 optical positioning accuracy of test results, adjust the position of the mold body to determine the level of the scan, so scan through the phantom center level.
4.3.2 commonly used in clinical use for scanning head scanning conditions.
4.3.3 motif stationary rack tilted at an angle, in accordance with the conditions in 4.3.2 scanned again.
4.3.4 ranging use workstation software, distance between the upper and lower edges of the cross-sectional image measurement phantoms, were recorded as L1 and L2.
4.3.5 using the equation (5) calculate the actual value of the gantry angle, compared with the set value, determines the accuracy of the gantry tilt angle.
α = arccosL1L2
(5)
Where.
α --- gantry angle size.
--- From the upper and lower edges of the transverse images, phantom between the vertical scan L1.
The distance between the upper and lower edges of the cross-sectional image after L2 --- rack inclination angle α motif.
4.4 Reconstruction thickness deviation
4.4.1 for axial slice thickness deviation measured using phantom embedded with a homogeneous background high contrast markers, markers have determined
The geometry, through its geometrical position reflects imaging reconstruction thickness; spiral CT machine for measuring the thickness of a sheet deviation or marker
Beads, the attenuation coefficient of not less than the marker material is aluminum, to ensure high signal to noise ratio, and the Z-axis direction of the maximum thickness or diameter should be
Between 0.05mm ~ 0.1mm.
4.4.2 The phantom axis perpendicular to the scanning level and placed in the scanning field center fixed.
4.4.3 According to the head of exposure conditions, the image reconstruction set the nominal thickness, axial or helical scan.
4.4.4 adjusted according to the mold body image viewing conditions specification window width and position, and for the record, layer thickness measurements reconstruction.
4.4.5 For axial scan reconstruction thickness variation measurement, current measurement methods There are two common motif.
a) Method One. adjust the window width to a minimum, change the window level until the marker image just completely disappeared, record the CT values, namely
CTmax, under the window width and position conditions, measured CT value marker near background is CTbackground, the CT value of half-height
CT values from the two and a half, denoted CThm, and then re-adjust the window level to CThm, this time measuring markers
Length, full width at half maximum (FWHM), and then using a fixed geometric relationship markers, calculated layer thickness measurements reconstruction; this
Methods commonly used to set the layer thickness is greater than 5mm thickness deviation detection reconstruction.
b) Method two. labels used in the method of determining the geometric relationship with minute details, by counting the number of details and
Combined with the geometric relationship between the details of the calculated thickness measurements reconstruction, the method can be used to detect and set the layer thickness relative to the diameter of details
Close rebuilding thickness deviation.
4.4.6 thickness deviation measurement method for the reconstruction of spiral CT machine is. with helical scan mode scanning markers, and a nominal thickness of 1/10
The image reconstruction interval, and the total width of the Z-axis direction of image reconstruction of at least 3 times the nominal thickness; with an appropriate ROI (e.g. thin markers
Tablets, the ROI is set for 2 times the diameter of the sheet, if it is micron beads, then the ROI set point. ) Measurements to obtain a series of helical sweep
Image description sheet or the average CT values beads material; record the average CT value for the Z axis as a function of the horizontal curve, and determine the
FWHM function curve, that is, as the FWHM of thickness measurements reconstruction.
Note 1. The reconstruction of the thickness of CT machine is referred to the default image reconstruction thickness.
Note 2. For older spiral CT machine, it is difficult to achieve a nominal thickness of 1/10 of the reconstructed image, you can fine-tune the scanning starting point to get multiple sets of image reconstruction, measuring
The average amount of CT values for these center of the image and make the curve, determine FWHM.
Note 3. For multi-slice CT, currently limited to the detection of multi-axial scan reconstruction slice thickness, testing phantoms having a defined geometric position markers Z
Axis direction should be long enough, if the length does not meet the needs of multi-scanning, can be divided according to the layout of the detector array open, detect, and
Z-axis center to ensure phantom markers as part of the array to be detected in the same scan levels.
Note 4. having used to determine the geometry of the high-contrast markers mold body should clearly be able to detect the smallest thickness d, the minimum thickness according to equation (6) Calculation
get.
d = T/cosθ (6)
Where.
The thickness of the T --- markers;
θ --- marker level scanning angle formed.
4.5 CT dose index
4.5.1 The use of human tissue-equivalent material homogeneous cylindrical phantom head die having a diameter of 160mm, the phantom diameter of 320mm, respectively, in the
Heart and 10mm from the surface there may be placed at a dose probe hole, relative error dose measuring instrument should be less than 5%, and has been calibrated.
4.5.2 The headform or phantom placed scanning field center, the axis of the cylindrical molded body with an effective level of vertical center of the scanning probe, the scanning probe
With its central location level.
4.5.3 respectively, according to the head and body commonly used in clinical conditions axial scan.
4.5.4 Records dosimeter readings and calculated CTDI100 and CTDIw according to formula (1) and (2).
4.6 CT value (water), noise and uniformity
4.6.1 using the homogeneous aqueous cylindrical phantom.
4.6.2 the mold body cylindrical axis perpendicular to the scanning level and in the scanning field center, the middle level of the cylindrical scan.
4.6.3 using the scanning head scanning conditions, and each radiation dose scan mode at the position of the center of the body should not exceed 50mGy.
4.6.4 Select the center of the image is about 500 pixels in size (about one-tenth of the mold body area) ROI, measure the ROI of the average CT
Value, standard deviation, wherein the average CT value of water as measured CT value, standard deviation divided by the contrast scale as noise measurement value n,
See equation (7).
n = σ CT water air water -CT × 100%
(7)
Where.
standard deviation σ water --- water phantom ROI measured;
CT Water --- water measured CT values;
Air --- CT CT value of air measurements.
CT Water -CT air --- contrast ruler.
4.6.5 Also in the image corresponds to the circumference of the watch clockwise 3,6,9,12 point, according to the motif of about 10mm at the edge of the image, select about
ROI 500 pixels size, the average CT values were measured four ROI, wherein the center of the image and 4.5.4 ROI average CT
Value as the maximum difference value of the uniformity measurement.
4.7 high contrast resolution
4.7.1 uses can be evaluated by direct observation or using phantom image transfer function (modulatedtransfer by calculating modulation
function, MTF) evaluate the spatial resolution high-contrast motifs, calculated MTF motif description and corresponding high contrast resolution measurements
Methods According to GB/T 19042.5.
4.7.2 for direct observation image motif should be evaluated with periodic detail, the spacing between the periodic structure that should be a single week
Equal to the width of the details of their own, effective attenuation coefficient differences in the details of the periodic effective attenuation coefficient and homogeneous background caused by CT values
The difference should be greater than 100HU.
4.7.3 The phantom placed in the center of the scan field, and the cylinder axis perpendicular to the scanning level.
4.7.4 4.5.3 with scanning conditions.
4.7.5 The molded body image viewing conditions or manual adjustment to achieve observer status clear that the details of most, but not greater than the window bit thin
Section CT CT value and the background value of the difference.
4.7.6 can distinguish count was recorded minimum size or MTF curve corresponding to 10% of the value of the spatial frequency detail as spatial periodicity
Discrimination of measuring value.
4.7.7 If a special algorithm to obtain high contrast resolution should first recording method according to 4.6.6 High Contrast the special algorithm corresponding
Measurement resolution, while 4.5 should press the scanned image reconstruction algorithm is special, according to the method of measuring 4.5 Application of the special reconstruction algorithm
After recording the image noise and the noise should be less than 1.5%.
4.8 low-contrast detectability capacity
4.8.1 Details molded body with diameter typically between 0.5mm ~ 4mm, and a background of 0.3% to 20% in the contrast between,
And the minimum diameter of not greater than 0.8mm, the minimum contrast ratio shall not exceed 0.5%.
4.8.2 The phantom placed in the center of the scan field, and its axis perpendicular to the scanning level.
4.8.3 4.5.3 with scanning conditions.
4.8.4 The molded body image viewing conditions or manual adjustment to achieve observer status that the details of the most clearly.
4.8.5 The minimum diameter of each recording contrast detail can be observed, and the noise level as amended, normalized to the noise level of 0.50%
Details diameter under background conditions, and then multiplied by contrast, mean different contrast details of the product as a low-contrast detectability Ability
Detection value.
4.8.6 noise level correction according to equation (8) is calculated.
Tσ2R3 = k1D
(8)
Where.
The T --- nominal thickness, in millimeters (mm);
σ --- noise level,%;
R --- the smallest detail can be observed diameter in millimeters (mm);
--- scale factor K, is a constant, regardless of their specific values;
D --- scanning dosage units of milli-Ge (mGy).
4.9 CT number linearity
4.9.1 using embedded with four or more different CT values phantom module, and the difference between the value of the CT module should be greater than 100HU.
4.9.2 using phantom instructions specified scanning conditions or is used in the clinic were scanning the head and body scanning conditions, respectively.
4.9.3 In the center select different modules of about 100 pixels size ROI, measure the average CT value.
4.9.4 in accordance with label instructions phantom various attenuation module attenuation coefficient in the corresponding ray radiation quality conditions, calculated the various modules
The average value is then calculated for each CT module, the nominal value of the resultant CT measurement of the module; the nominal value of CT in this ray radiation quality conditions
CT value difference, the difference between the maximum evaluation parameters were recorded as CT values linear.
Appendix A
(Normative)
CT machine test items and requirements
CT machine test items and requirements of Table A.1.
Table A.1 CT machine test items and requirements
No. Test item testing requirements
Acceptance state detection stability testing
Evaluation Criteria Evaluation Criteria Evaluation Criteria cycle
Diagnosis bed positioning accuracy
mm
Positioning ± 2 ± 2 2
Homing ± 2 ± 2 2
per month
Optical precision positioning
mm
- ± 2 ± 3 - -
Gantry angle precision
(°)
- ± 2 - - -
Reconstruction thickness deviation (s)
mm
s≥8 ± 10% ± 15%
8 > s > 2 ± 25% ± 30%
s≤2 ± 40% ± 50%
And the difference between the baseline value
± 20% or ± 1 mm,
In greater control
Per year
CTDIw
mGy
Head phantom
And refers to the manufacturer's instructions
Marked difference of less than ± 10%
And refers to the manufacturer's instructions
Marked difference of less than ± 15%,
If there is no technical specification means
Standard reference should be < 50
Body phantom
And refers to the manufacturer's instructions
Marked difference of less than ± 10%
And refers to the manufacturer's instructions
Marked difference of less than ± 15%,
If there is no technical specification means
Standard reference should be < 30
And the difference between the baseline value
Within ± 15%
Per year
CT value (water)
HU
Water phantom ± 4 ± 6
And the difference between the baseline value ± 4
Within
per month
Uniformity
HU
Water or equivalent water
Homogeneous phantom
± 5 ± 6
Baseline values differ ± 2
Within
per month
noise
Head phantom
CTDIw <
50mGy
< 0.35 < 0.45
And the difference between the baseline value
Within ± 10%
Six months
High contrast resolution
lp/cm
General Algorithm
CTDIw <
50mGy
High Contrast Algorithm
CTDIw <
50mGy
Number of Pairs
MTF10
Number of Pairs
MTF10
> 6.0
> 11
Number of Pairs
MTF10
Number of Pairs
MTF10
> 5.0
> 10
And the difference between the baseline value
Within ± 15%
Six months
Table A.1 (CONTINUED)
No. Test item testing requirements
Acceptance state detection stability testing
Evaluation Criteria Evaluation Criteria Evaluation Criteria cycle
Low-contrast detectability
ability
- < 2.5 < 3.0 - -
CT value linearity,
HU
- 50 60 - -
Note. - indicates that this is not detected.
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