ASTM E2597-07

Standard Practice for Manufacturing Characterization of Digital Detector Arrays

SIGNIFICANCE AND USE
This practice provides a means to compare DDAs on a common set of technical measurements, realizing that in practice adjustments can be made to achieve similar results even with disparate DDAs given geometric magnification, or other industrial radiologic settings that may compensate for one shortcoming of a device.
A user must understand the definitions and corresponding performance parameters used in this practice in order to make an informed decision on how a given DDA can be used in the target application.
The factors that will be evaluated for each DDA are: basic spatial resolution (SRb), efficiency (Detector SNR-normalized (dSNRn) at 1 mGy, for different energies and beam qualities), achievable contrast sensitivity (CSa), specific material thickness range (SMTR), image lag, burn-in, bad pixels and internal scatter radiation (ISR).
SCOPE
1.1 This practice describes the evaluation of Digital Detector Arrays (DDAs), and assures that one common standard exists for quantitative comparison of DDAs so that an appropriate DDA is selected to meet NDT requirements.
1.2 This practice is intended for use by manufacturers or integrators of DDAs to provide quantitative results of DDA characteristics for NDT user or purchaser consumption. Some of these tests require specialized test phantoms to assure consistency among results among suppliers or manufacturers. These tests are not intended for users to complete, nor are they intended for long term stability tracking and lifetime measurements. However, they may be used for this purpose, if so desired.
1.3 The values stated in SI are to be regarded as the standard.
1.4 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: 30-Nov-2007
• ICS: 11.040.50 - Radiographic equipment
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.01 - Radiology (X and Gamma) Method

Relations

• Replaced By: ASTM E2597-07e1 - Standard Practice for Manufacturing Characterization of Digital Detector Arrays
• Effective Date: 01-Dec-2007
• Referred By: ASTM E94/E94M-22 - Standard Guide for Radiographic Examination Using Industrial Radiographic Film
• Effective Date: 01-Dec-2007
• Referred By: ASTM E2736-17(2022) - Standard Guide for Digital Detector Array Radiography
• Effective Date: 01-Dec-2007
• Referred By: ASTM E2699-23 - Standard Practice for Digital Imaging and Communication in Nondestructive Evaluation (DICONDE) for Digital X-ray (DX) Test Methods
• Effective Date: 01-Dec-2007
• Referred By: ASTM E1475-13(2023) - Standard Guide for Data Fields for Computerized Transfer of Digital Radiological Examination Data
• Effective Date: 01-Dec-2007
• Referred By: ASTM E3398-23 - Standard Guide for Digital Neutron Radiography
• Effective Date: 01-Dec-2007
• Referred By: ASTM E1735-19 - Standard Practice for Determining Relative Image Quality Response of Industrial Radiographic Imaging Systems from 4 to 25 MeV
• Effective Date: 01-Dec-2007
• 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-Dec-2007
• Referred By: ASTM E2446-23 - Standard Practice for Manufacturing Characterization of Computed Radiography Systems
• Effective Date: 01-Dec-2007
• Referred By: ASTM E3166-20e1 - Standard Guide for Nondestructive Examination of Metal Additively Manufactured Aerospace Parts After Build
• Effective Date: 01-Dec-2007
• 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-Dec-2007

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: E 2597 – 07
Standard Practice for
Manufacturing Characterization of Digital Detector Arrays
This standard is issued under the fixed designation E 2597; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope E 2445 Practice for Qualification and Long-Term Stability
of Computed Radiology Systems
1.1 This practice describes the evaluation of Digital Detec-
E 2446 Practice for Classification of Computed Radiology
tor Arrays (DDAs), and assures that one common standard
Systems
exists for quantitative comparison of DDAs so that an appro-
priate DDA is selected to meet NDT requirements.
3. Terminology
1.2 This practice is intended for use by manufacturers or
3.1 Definitions of Terms Specific to This Standard:
integrators of DDAs to provide quantitative results of DDA
3.1.1 digital detector array (DDA) system—an electronic
characteristics for NDT user or purchaser consumption. Some
device that converts ionizing or penetrating radiation into a
of these tests require specialized test phantoms to assure
discrete array of analog signals which are subsequently digi-
consistency among results among suppliers or manufacturers.
tized and transferred to a computer for display as a digital
These tests are not intended for users to complete, nor are they
image corresponding to the radiologic energy pattern imparted
intended for long term stability tracking and lifetime measure-
upon the input region of the device. The conversion of the
ments. However, they may be used for this purpose, if so
ionizing or penetrating radiation into an electronic signal may
desired.
transpire by first converting the ionizing or penetrating radia-
1.3 The values stated in SI are to be regarded as the
tionintovisiblelightthroughtheuseofascintillatingmaterial.
standard.
These devices can range in speed from many seconds per
1.4 This standard does not purport to address all of the
image to many images per second, up to and in excess of
safety concerns, if any, associated with its use. It is the
real-time radioscopy rates (usually 30 frames per seconds).
responsibility of the user of this standard to establish appro-
3.1.2 active DDA area—the size and location of the DDA,
priate safety and health practices and determine the applica-
which is recommended by the manufacturer as usable.
bility of regulatory limitations prior to use.
3.1.3 signal-to-noise ratio (SNR)—quotient of mean value
2. Referenced Documents of the intensity (signal) and standard deviation of the intensity
2 (noise). The SNR depends on the radiation dose and the DDA
2.1 ASTM Standards:
system properties.
E 1316 Terminology for Nondestructive Examinations
3.1.4 contrast-to-noise ratio (CNR)—quotient of the differ-
E 1647 Practice for Determining Contrast Sensitivity in
enceofthemeansignallevelsbetweentwoimageareasandthe
Radiology
standarddeviationofthesignallevels.Asappliedhere,thetwo
E 1742 Practice for Radiographic Examination
image areas are the step-wedge groove and base material. The
E 1815 Test Method for Classification of Film Systems for
standard deviation of the intensity of the base material is a
Industrial Radiography
measure of the noise. The CNR depends on the radiation dose
E 2002 Practice for Determining Total Image Unsharpness
and the DDA system properties.
in Radiology
3.1.5 basic spatial resolution (SRb)—the basic spatial reso-
lution indicates the smallest geometrical detail, which can be
resolved using the DDA. It is similar to the effective pixel size.
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
3.1.6 detector signal-to-noise ratio–normalized (dSNRn)—
structive Testing and is the direct responsibility of Subcommittee E07.01 on
the SNR is normalized for basic spatial resolution SRb as
Radiology (X and Gamma) Method.
Current edition approved Dec. 1, 2007. Published January 2008.
measureddirectlyonthedetectorwithoutanyobjectotherthan
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
beam filters in the beam path.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3.1.7 internal scatter radiation (ISR)—scattered radiation
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. within the detector.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2597–07
3.1.8 effıciency—dSNRn (see 3.1.6) divided by the square 4. Significance and Use
root of the dose (in mGy) and is used to measure the response
4.1 This practice provides a means to compare DDAs on a
of the detector at different beam energies and qualities.
common set of technical measurements, realizing that in
3.1.9 achievable contrast sensitivity (CSa)—optimum con-
practice adjustments can be made to achieve similar results
trast sensitivity (see Terminology E 1316 for a definition of
even with disparate DDAs given geometric magnification, or
contrast sensitivity) obtainable using a standard phantom with
other industrial radiologic settings that may compensate for
an x-ray technique that has little contribution from scatter.
one shortcoming of a device.
3.1.10 specific material thickness range (SMTR)—the ma-
4.2 A user must understand the definitions and correspond-
terial thickness range within which a given image quality is
ing performance parameters used in this practice in order to
achieved.As applied here, the wall thickness range of a DDA,
make an informed decision on how a given DDA can be used
whereby the thinner wall thickness is limited by 80 % of the
in the target application.
maximum gray value of the DDA and the thicker wall
4.3 The factors that will be evaluated for each DDA are:
thickness by a SNR of 130:1 for 2 % contrast sensitivity and
basic spatial resolution (SRb), efficiency (Detector SNR-
SNR of 250:1 for 1 % contrast sensitivity. Note that SNR
normalized (dSNRn) at 1 mGy, for different energies and beam
values of 130:1 and 250:1 do not guarantee that 2 % and 1 %
qualities), achievable contrast sensitivity (CSa), specific mate-
contrast sensitivity values will be achieved, but are being used
rialthicknessrange(SMTR),imagelag,burn-in,badpixelsand
to designate a moderate quality image, and a higher quality
internal scatter radiation (ISR).
image respectively.
3.1.11 frame rate—number of frames acquired per second.
5. Apparatus
3.1.12 lag—residual signal in the DDA that occurs shortly
5.1 Duplex Wire Image Quality Indicator for SRb—The
after the exposure is completed.
duplex wire quality indicator corresponds to the design speci-
3.1.13 burn-in—change in gain of the scintillator that per-
fied in Practice E 2002 for the measurement of SRb and not
sists well beyond the exposure.
unsharpness.
3.1.14 GlobalLag1f (global lag 1st frame)—the ratio of
5.2 Step-Wedge Image Quality Indicator—The wedge has
mean signal value of the first frame of the DDA where the
six steps in accordance with the drawing provided in Fig. 1.
x-rays are completely off to the mean signal value of an image
The wedge may be formed with built-in masking to avoid
where the x-rays are fully on.This parameter is specifically for
X-ray scatter and undercut. In lieu of built-in masking, the
the integration time used during data acquisition.
step-wedge may be inserted into a lead frame. The Pb frame
3.1.15 GlobalLag1s (global lag 1 s)—the projected value of
can then extend another 25.4 mm (1 in.) about the perimeter of
GlobalLag1f for an integration time of 1 second.
the step-wedge, beyond the support. The slight overlap of the
3.1.16 GlobalLag60s (global lag 60 s)—the ratio between
Pb support with the edges of the step-wedge (no more than 6
mean gray value of an image acquired with the DDA after 60
mm (~0.25 in.) assures a significantly reduced number of
s where the x-rays are completely off, to same of an image
X-raystoleak-throughunderthestep-wedgethatwillcontami-
where the x-rays are fully on.
nate the data acquired on each step. The step-wedges shall be
3.1.17 bad pixel—a pixel identified with a performance
formed of three different materials Aluminum–6061,
outside of the specification range for a pixel of a DDA as
Titanium–Ti-6Al-4V, and Inconel 718 with a center groove in
defined in 6.2.
eachstep,asshowninFig.1.Thedimensionsofthewedgesfor
3.1.18 step-wedge—a stepped block of a single metallic
the different materials are shown in Table 1.
alloy with a thickness range that is to be manufactured in
5.3 Filters for Measuring Effıciency of the DDA—The
accordance with 5.2.
following filter thicknesses (5.3.1-5.3.7) and alloys (5.3.8)
3.1.19 phantom—apartoritembeingusedtoquantifyDDA
shall be used to obtain different radiation beam qualities and
characterization metrics.
are to be placed at the output of the beam. The tolerance for
3.1.20 DDAoffset image—imageoftheDDAintheabsence
these thicknesses shall be 60.1 mm (60.004 in.).
of x-rays providing the background signal of all pixels.
5.3.1 No external filter (50 kV).
3.1.21 DDAgainimage—imageobtainedwithnostructured 5.3.2 30 mm (1.2 in.) Al (90 kV).
object in the x-ray beam to calibrate pixel response in a DDA.
5.3.3 40 mm (1.6 in.) Al (120 kV).
3.1.22 calibration—correction applied for the offset signal, 5.3.4 3 mm (0.12 in.) Cu (120 kV).
and the non-uniformity of response of any or all of the x-ray 5.3.5 10 mm (0.4 in.) Fe (160 kV).
beam, scintillator and the read out structure.
5.3.6 8 mm (0.3 in.) Cu (220 kV).
3.1.23 gray value—the numeric value of a pixel in a DDA 5.3.7 16 mm (0.6 in.) Cu (420 kV).
image. This is typically interchangeable with the term pixel 5.3.8 The filters shall be placed directly at the tube window.
value, detector response, Analog-to-Digital Unit, and detector The aluminum filter shall be composed of Aluminum 6061.
signal. The Copper shall be composed of 99.9 % purity or better. The
Iron filter shall be composed of Stainless steel 304.
3.1.24 pixel value—the numeric value of a pixel in a DDA
image. This is typically interchangeable with the term gray
NOTE 1—Radiation qualities in 5.3.2 and 5.3.3 are in accordance with
value.
DQE standard IEC62220-1, and radiation quality in 5.3.4 and 5.3.5 are in
3.1.25 saturation gray value—the maximum possible gray
accordance with ISO 7004. Radiation quality in 5.3.6 is used also in Test
value of the DDA after offset correction. Method E 1815, Practice E 2445, and Practice E 2446.
E2597–07
FIG. 1 Step-Wedge Drawing (dimensions are listed in Table 1)
5.4 Filters for Measuring, Burn-In and Internal Scatter calibration procedures. This is to assure that data collected by
Radiation—The filters for measuring burn-in and ISR shall manufacturers will closely match that collected when the
consist of a minimum 16 mm (0.6 in.) thick Cu plate (5.3.7) system is entered into service.
100 by 75 mm (4 by 3 in.) with a minimum of one sharp edge.
6.2 Bad Pixel Standardization for DDAs—Manufacturers
If the DDA is smaller than 15 by 15 cm (5.9 by 5.9 in.) use a
typically have different methods for correcting bad pixels.
plate that is dimensionally 25 % of the active DDA area.
Images collected for qualification testing shall be corrected for
bad pixels as per manufacturer’s bad pixel correction proce-
6. Calibration and Standardization
dure wherever required. In this section a standardized nomen-
6.1 DDA Calibration Method—Prior to qualification testing clature is presented. The following definitions enable classifi-
the DDA shall be calibrated for offset and, or gain (see 3.1.20 cation of pixels in a DDA as bad or good types. The
and 3.1.21) to generate corrected images per manufacturer’s manufacturers are to use these definitions on a statistical set of
recommendation. It is important that the calibration procedure detectors in a given detector type to arrive at “typical” results
be completed as would be done in practice during routine for bad pixels for that model. The identification and correction
E2597–07
TABLE 1 Dimension of Step-Wedge for Three Different Materials Used as Image Quality Indicators in This Practice
Material Unit A B1 B2 B3 B4 B5 B6 C D E
Step-wedge (Inconel 718) mm 35.0 1.25 2.5 5.0 7.5 10.0 12.5 175.0 70.0 35.0
Tolerance (6) microns 200 25 25 38 38 38 38 200 200 200
5 % Groove microns 63 125 250 375 500 625
Tolerance (6) microns 10 10 10 10 10 10
Material Unit A B1 B2 B3 B4 B5 B6 C D E
Step-wedge (Ti-6Al-4V) mm 35.0 2.5 5.0 7.5 10.0 20.0 30.0 175.0 70.0 35.0
Tolerance (6) microns 200 50 50 50 50 50 50 200 200 200
5 % Groove microns 125 250 375 500 1000 1500
Tolerance (6) microns 10 10 10 10 10 10
Material Unit A B1 B2 B3 B4 B5 B6 C D E
Step-wedge (Al-6061) mm 35.0 10.0 20.0 40.0 60.0 80.0 100.0 175.0 70.0 35.0
Tolerance (6) microns 200 100 100 300 300 300 300 200 200 200
5 % Groove microns 500 1000 2000 3000 4000 5000
Tolerance (6) microns 13 25 50 50 50 50
Material Unit A B1 B2 B3 B4 B5 B6 C D E
Step-wedge (Inconel 718) inch 1.4 0.05 0.1 0.2 0.3 0.4 0.5 6.9 2.8 1.4
Tolerance (6) mils 8.0 1.0 1.0 1.5 1.5 1.5 1.5 8.0 8.0 8.0
5 % Groove mils 2.5 4.9 9.8 14.8 19.7 24.6
Tolerance (6) mils 0.5 0.5 0.5 0.5 0.5 0.5
Material Unit A B1 B2 B3 B4 B5 B6 C D E
Step-wedge (Ti-6Al-4V) inch 1.4 0.1 0.2 0.3 0.4 0.8 1.2 6.9 2.8 1.4
Tolerance (6) mils 8.0 2.0 2.0 2.0 2.0 2.0 2.0 8.0 8.0 8.0
5 % Groove mils 4.9 9.8 14.8 19.7 39.4 59.1
Tolerance (6) mils 0.5 0.5 0.5 0.5 0.5 0.5
Material Unit A B1 B2 B3 B4 B5 B6 C D E
Step-wedge (Al-6061) inch 1.4 0.4 0.8 1.6 2.4 3.1 3.9 6.9 2.8 1.4
Tolerance (6) mils 8.0 4.0 4.0 12.0 12.0 12.0 12.0 8.0 8.0 8.0
5 % Groove mils 19.7 39.4 78.7 118.1 157.5 196.9
Tolerance (6) mils 0.5 1.0 2.0 2.0 2.0 2.0
of bad pixels in a delivered DDA remains in the purview of 6.2.1.7 Bad Neighborhood Pixel—Pixel, where all 8 neigh-
agreement between the purchaser and the supplier. boring pixels are bad pixels, is also considered a bad pixel.
6.2.1 Definition and Test of Bad Pixels:
6.2.2 Types or Groups of Bad Pixels:
6.2.1.1 Dead Pixel—Pixels that have no response, or that
6.2.2.1 Single Bad Pixel—A single bad pixel is a bad pixel
give a constant response independent of radiation dose on the
with only good neighborhood pixels.
detector.
6.2.2.2 Cluster of Bad Pixels—Two or more connected bad
6.2.1.2 Over Responding Pixel—Pixels whose gray values
pixels are called a cluster. Pixels are called connected if they
are greater than 1.3 times the median gray value of an area of
are connected by a side or a corner (8-neighborhood possibili-
a minimum of 21321 pixels. This test is done
...