ASTM E2445-05

Standard Practice for Qualification and Long-Term Stability of Computed Radiology Systems

SCOPE
1.1 This practice specifies the fundamental parameters of computed radiography systems to assure satisfactory and repeatable results for nondestructive testing.
1.2 This practice describes the evaluation of Computed Radiology (CR) systems for industrial radiography. It is intended to ensure that the evaluation of image quality, as far as this is influenced by the scanner/IP system, meets the needs of users and enables the test of long-term stability.
1.3 Each of the tests described may be performed with individual gages specified. The user shall decide which tests shall be used for system control using individual test objects or the CR test phantom² (Appendix X1). The computed radiological tests, specified as "user tests" in this practice, may be utilized at appropriate intervals determined by the user, based on the application of the examination operations. The tests shall be appropriate for the materials and range of use of the system. Fading, uniformity, and erasure tests shall also be part of the control system. All other tests for qualification and capability are to be performed and certified by the CR equipment manufacturer.
1.4 The values stated in SI units are to be regarded as the standard. Values in inch-pound units are for information purposes.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-May-2005
• ICS: 19.100 - Non-destructive testing
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.01 - Radiology (X and Gamma) Method

Relations

• Replaced By: ASTM E2445-05(2010) - Standard Practice for Qualification and Long-Term Stability of Computed Radiology Systems
• Effective Date: 01-Jun-2010
• Referred By: ASTM E1475-13(2023) - Standard Guide for Data Fields for Computerized Transfer of Digital Radiological Examination Data
• Effective Date: 01-Jun-2005
• Referred By: ASTM E746-18 - Standard Practice for Determining Relative Image Quality Response of Industrial Radiographic Imaging Systems
• Effective Date: 01-Jun-2005
• Referred By: ASTM E2662-15(2022) - Standard Practice for Radiographic Examination of Flat Panel Composites and Sandwich Core Materials Used in Aerospace Applications
• Effective Date: 01-Jun-2005
• Referred By: ASTM E2446-23 - Standard Practice for Manufacturing Characterization of Computed Radiography Systems
• Effective Date: 01-Jun-2005
• Referred By: ASTM E2007-10(2023) - Standard Guide for Computed Radiography
• Effective Date: 01-Jun-2005
• Referred By: ASTM E2597/E2597M-22 - Standard Practice for Manufacturing Characterization of Digital Detector Arrays
• Effective Date: 01-Jun-2005
• Referred By: ASTM E2033-17 - Standard Practice for Radiographic Examination Using Computed Radiography (Photostimulable Luminescence Method)
• Effective Date: 01-Jun-2005
• Referred By: ASTM E1647-16(2022) - Standard Practice for Determining Contrast Sensitivity in Radiology
• Effective Date: 01-Jun-2005
• Referred By: ASTM E2736-17(2022) - Standard Guide for Digital Detector Array Radiography
• Effective Date: 01-Jun-2005
• Referred By: ASTM E1114-20 - Standard Test Method for Determining the Size of Iridium-192, Cobalt-60, and Selenium-75 Industrial Radiographic Sources
• Effective Date: 01-Jun-2005
• Referred By: ASTM E3166-20e1 - Standard Guide for Nondestructive Examination of Metal Additively Manufactured Aerospace Parts After Build
• Effective Date: 01-Jun-2005

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E2445 – 05
Standard Practice for
Qualification and Long-Term Stability of Computed
Radiology Systems
This standard is issued under the fixed designation E2445; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This practice specifies the fundamental parameters of 2.1 ASTM Standards:
computed radiography systems to assure satisfactory and E1316 Terminology for Nondestructive Examinations
repeatable results for nondestructive testing. E1647 Practice for Determining Contrast Sensitivity in
1.2 This practice describes the evaluation of Computed Radiology
Radiology (CR) systems for industrial radiography. It is E2002 Practice for Determining Total Image Unsharpness
intended to ensure that the evaluation of image quality, as far in Radiology
as this is influenced by the scanner/IP system, meets the needs E2007 Guide for Computed Radiography
of users and enables the test of long-term stability. E2033 Practice for Computed Radiology (Photostimulable
1.3 Each of the tests described may be performed with Luminescence Method)
individual gages specified. The user shall decide which tests E2446 Practice for Classification of Computed Radiology
shall be used for system control using individual test objects or Systems
the CR test phantom (Appendix X1). The computed radio-
3. Terminology
logical tests, specified as “user tests” in this practice, may be
3.1 Definitions—The definition of terms relating to gamma-
utilized at appropriate intervals determined by the user, based
on the application of the examination operations. The tests and X-radiology, which appear in Terminology E1316, Guide
E2007, and Practice E2033 shall apply to the terms used in this
shall be appropriate for the materials and range of use of the
system. Fading, uniformity, and erasure tests shall also be part practice.
3.2 Definitions of Terms Specific to This Standard:
of the control system. All other tests for qualification and
3.2.1 aliasing—pre-sampled high spatial frequency signals
capability are to be performed and certified by the CR
equipment manufacturer. beyond the Nyquist frequency (given by the pixel distance)
reflected back into the image at lower spatial frequencies.
1.4 The values stated in SI units are to be regarded as the
standard. Values in inch-pound units are for information 3.2.2 computed radiology system (CR system)—a complete
system of a storage phosphor imaging plate (IP) and corre-
purposes.
1.5 This standard does not purport to address all of the sponding read out unit (scanner or reader), which converts the
information of the IP into a digital image (see also Guide
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- E2007).
3.2.3 computed radiology system class—a particular group
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. of storage phosphor imaging plate systems, which is charac-
terized by a SNR (Signal-to-Noise Ratio) range shown in
Table 1 and by a certain unsharpness range (for example,
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
MTF -value) in a specified exposure range.
structive Testing and is the direct responsibility of Subcommittee E07.01 on
3.2.4 CR phantom—a device containing an arrangement of
Radiology (X and Gamma) Method.
test targets to evaluate the quality of a CR system, as well as
Current edition approved June 1, 2005. Published June 2005. DOI: 10.1520/
E2445-05.
monitoring the quality of the chosen system.
The sole source of supply of the apparatus known to the committee at this time
is Nuclear Associates, A Division of Cardinal Health, 120 Andrews Road,
Hicksville, NY 11801, Phone: [phone], Catalog Number: 07-605-2435. If For referenced ASTM standards, visit the ASTM website, www.astm.org, or
you are aware of alternative suppliers, please provide this information to ASTM contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
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E2445 – 05
3.2.5 gain/amplification—opto-electrical gain setting of the 4.4.1.2 The tests described in 6.2.1 through 6.2.6 require
scanning system. usage of quality indicators of 5.1 or the CR test phantom shall
be used regularly at user-defined intervals to test the basic
3.2.6 ISO speed S —defines the speed of a CR system and
IPx
is calculated from the reciprocal dose value, measured in Gray, performance. The documentation shall contain:
whichisnecessarytoobtainaspecifiedminimumSNRofaCR (1) Spatial resolution (by duplex-wire method, optional
system. converging line pairs),
3.2.7 laser beam jitter—a lack of smooth movement of the (2)Contrast(recognizedcontrastpercentageofthematerial
imaging plate/laser scanning device, which results in lines of to examine),
the image, which consist of a series of steps. (3) Slipping (yes/no),
3.2.8 linearized signal intensity—a numerical signal value (4) Jitter (yes/no),
of a picture element (pixel) of the digital image, which is
(5) Shading (percentage at selected distance),
proportional to the radiation dose. The linearized signal inten- (6) Radiation parameters of the performed tests, and
sity is zero, if the radiation dose is zero.
(7) Date and operator name.
3.2.9 long-term stability—performance measurements of a
4.4.1.3 Fading tests should be performed only if the scanner
CR system over the life-cycle of the devices, used to evaluate or IP-brand is changed without data from the CR equipment
relative system performance over time.
manufacturer, or the system is used under extreme (beyond
3.2.10 scanner slippage—the slipping of an IP in a scanner manufacturer’s recommendation) temperature conditions. The
transport system resulting in fluctuation of intensity of hori- fadingshouldbelessthan50 %intheexpectedperiodbetween
zontal image lines. exposure and scan.
3.2.11 signal-to-noise ratio (SNR)—quotient of mean value 4.4.1.4 The IPs shall be checked for artifacts (6.2.7) and
of the linearized signal intensity and standard deviation of the proper erasure (6.2.6).
noise (intensity distribution) at this signal intensity. The SNR 4.4.1.5 Degradation of IPs or photo multipliers in the
depends on the radiation dose and the CR system properties. scanner may reduce the system sensitivity after extensive
usage. For this reason, the SNR should be measured at longer
4. Significance and Use intervals (for example, annual period) by the user or service
personnel. The SNR shall not be less than 90 % of the original
4.1 There are several factors affecting the quality of a CR
value. The increase of the SNR can be accepted without limits,
image including the spatial resolution of the IP system,
if the system unsharpness is not increased.
geometrical unsharpness, scatter and contrast sensitivity
(signal/noise ratio). There are several additional factors (for
5. Apparatus—CR Quality Indicators
example, scanning parameters), which affect the accurate
reading of images on exposed IPs using an optical scanner. 5.1 Description of CR Quality Indicators for User Tests—
4.2 The quality factors can be determined most accurately The following is a description of CR quality indicators, which
will be identified by reference to this practice.
by the CR equipment manufacturer tests as described in
Practice E2446. Individual test targets, which are recom- 5.1.1 Contrast Sensitivity Quality Indicator:
mended for practical user tests, are described for quality 5.1.1.1 The description of the contrast sensitivity target
assurance.These tests can be carried out either separately or by corresponds to Practice E1647. For use with this practice, three
the use of the CR phantom (Appendix X1). This CR phantom targets are made from aluminum (Material Group 02), copper
incorporatesmanyofthebasicqualityassessmentmethodsand (Material Group 4) and stainless steel (Material Group 1). The
those associated with the correct functioning of a CR system, target thickness is 12.5 mm (0.50 in.) aluminum, 6.3 mm (0.25
including the scanner, for reading exposed plates and incor- in.) copper and stainless steel. Each target contains a contrast
rectly erasing IPs for future use of each plate. area for 1, 2, 3, and 4 % wall-thickness contrast sensitivity.
4.3 This practice is for users of industrial CR systems. This 5.1.2 Duplex Wire Quality Indicator:
practice defines the tests to be performed, by users of CR 5.1.2.1 The description of the duplex wire quality indicator
systems, periodically to evaluate the CR systems to prove
corresponds to Practice E2002. The gage shall be oriented at a
proper performance over the life-cycle of the system. 5° angle to the direction of the scanned lines (fast-scan
4.4 Application of Various Tests and Test Methods direction) or the perpendicular direction (slow-scan-direction).
4.4.1 Tests after Repair, Upgrade or the Use of Another IP 5.1.3 Converging Line Pair Quality Indicator:
Type:
5.1.3.1 The target consists of five converging strips of lead
Since modifications, such as repair or upgrade of the CR (0.03mm(0.001in.)thickness),whichcanbeusedforaspatial
scanner and improved IP may improve the functionality of the resolution test by reading the limit of recognizable line pairs. It
system, specialized tests are required to prove the proper shall cover a range from 1.5 to 20 line pairs per mm (lp/mm).
Two quality indicators shall be used, one in parallel with the
performance of the CR system.
scanned lines and the other one oriented in the perpendicular
4.4.1.1 User Tests for Long-term Stability—Quality assur-
direction.
ance in test laboratories requires periodical tests of the CR
5.1.4 Linearity Quality Indicators:
system to prove the proper performance of the system. The
time interval depends on the degree of usage of the system and 5.1.4.1 Rulers of high-absorbing materials are located on
shall be defined by the user and consideration of the CR theperimeterofthescannedrange.Twoqualityindicatorsshall
equipment manufacturer’s information. be used, one parallel with the scanned lines and the other one
E2445 – 05
largepixelsizesettings(highunsharpness)thanforsmallpixelsizesetting
oriented in the perpendicular direction. The scaling should be
(low unsharpness).
at least in mm or tenths of inches.
5.1.5 T-target: 5.2.2 Initial Assessment of CR Quality Indicators:
5.1.5.1 This CR quality indicator consists of a thin plate of 5.2.2.1 For initial quality assessment, examine the radio-
brassorcopper(#0.5mm(#0.02in.)thick)withsharpedges. graphic image(s) of the CR phantom or the separated quality
This plate is manufactured in a T-shape with 0.5 mm (0.2 in.) indicators on the monitor (or hard copy) for the features
wide segments. The T should have a size of at least 50 by 70 described in 5.1.1 to 5.1.8 and 6.2.1 to 6.2.8. The results can
mm(2by2 ⁄4in.).Itshallbealignedperpendicularandparallel provide the basis of agreement between contracting parties.
to the direction of the scanned lines and is used to check for 5.3 Periodical Control:
laser jitter and may be used to measure a modulation transfer 5.3.1 The CR quality indicators of 5.1.1 through 5.1.7
function of the complete system (see Fig. X1.1). (alignment by 5.1.8) or the CR phantom shall be exposed and
the results examined at any interval agreed between the
5.1.6 Scanner Slipping Quality Indicator:
contracting parties. For periodical control, ensure that the
5.1.6.1 The quality indicator consists of a homogeneous
agreed quality values of the tests 6.1.3 and 6.2.1 to 6.2.8 are
strip of aluminum 0.5 mm (0.02 in.) in thickness. The quality
achieved.
indicator has the shape of a rectangle (see Fig. X1.1) and shall
5.4 Imaging Plate Fading:
be aligned perpendicular and parallel to the direction of the
5.4.1 The intensity of the stored image in the imaging plate
scanned lines.
will decrease over time (called “fading”). The measurement of
5.1.7 Shading Quality Indicator:
fading characteristic shall be done by performing the following
5.1.7.1 Different shading quality indicators may be used.
steps:
One type is based on the homogeneous exposure of an imaging
5.4.1.1 Expose a plate homogeneously using typical expo-
plate (IP) with a thin Al-plate 0.5 to 1.0 mm (0.06 to 0.04 in.)
sure conditions. For documentation, the following parameters
above the IP. The exposure shall be made with low-energy
shall be recorded: kV, mAs, SDD, pre-filter and plate material,
radiation (50 to 100 keV).
and thickness. The exposed image shall have an intensity
5.1.7.2 Another type is the shading quality indicator of the
between 70 and 90 % of the maximum possible intensity of the
CR test phantom (see X1.1).
CR reader at lowest gain and under linearized condition.
5.1.8 Central Beam Alignment Quality Indicator (BAM-
5.4.1.2 Readout the imaging plate five minutes after expo-
snail):
sure.
5.1.8.1 The alignment quality indicator consists of a roll 1.5
5.4.1.3 Set the linearized read-out intensity of this measure-
to 2.0 mm high (0.06 to 0.08 in.) of thin lead foil separated by
ment as reference (=100 %).
a spacer of 0.1 to 0.2 mm (0.004 to 0.008 in.) of low-absorbing
5.4.1.4 Always expose the imaging plate with the same
material (see X1.2).
X-ray parameters (kV, mAs, and distance).
5.2 Application Procedures for CR Quality Indicators—The
5.4.1.5 Change the time between exposure and read-out.
CR quality indicators provide an evaluation of the quality of a
The time interval between exposure and readout will be
CR system as well as for a periodical quality control.Arrange-
doubled for every measurement; steps are 15 min, 30 min, 1 h,
ment of the CR quality indicators shall be in accordance with
2 h, 4 h, and so forth, up to 4 days or as needed to match
this practice, or as specified by the cognizant engineering
application requirement for read-out.
organization.
5.4.1.6 Plot the linearized read-out intensity (gray value)
5.2.1 Exposure of CR Quality Indicators (User Test):
versus time between exposure and read-out of the imaging
5.2.1.1 The CR quality indicators can be applied separately
plate.
or all together in the CR phantom. The selected set of CR
5.4.2
...