ASTM E1114-20

Standard Test Method for Determining the Size of Iridium-192, Cobalt-60, and Selenium-75 Industrial Radiographic Sources

SIGNIFICANCE AND USE
4.1 One of the factors affecting the quality of a radiographic image is geometric unsharpness. The degree of geometric unsharpness is dependent upon the size of the source, the distance between the source and the object to be radiographed, and the distance between the object to be radiographed and the film or digital detector. This test method allows the user to determine the size of the source and to use this result to establish source to object and object to film or detector distances appropriate for maintaining the desired degree of geometric unsharpness.
Note 1: The European standard CEN EN 12579 describes a simplified procedure for measurement of source sizes of Ir-192, Co-60, and Se-75. The resulting source size of Ir-192 is comparable to the results obtained by this test method.
SCOPE
1.1 This test method covers the determination of the size of Iridium-192, Cobalt-60, and Selenium-75 radiographic sources. The determination is based upon measurement of the image of the source in a projection radiograph of the source assembly and comparison to the measurement of the image of a reference sample in the same radiograph or the source guide tube.  
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.  
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Nov-2020
• ICS: 19.100 - Non-destructive testing
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.01 - Radiography (X and Gamma) Method

Relations

• Refers: ASTM E1316-24 - Standard Terminology for <?Pub Dtl?>Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Refers: ASTM E1316-19b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2019
• Refers: ASTM E1316-19 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Mar-2019
• Refers: ASTM E1316-18 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jan-2018
• Refers: ASTM E1316-17a - Standard Terminology for Nondestructive Examinations
• Effective Date: 15-Jun-2017
• Refers: ASTM E1316-17 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Feb-2017
• Refers: ASTM E1316-16a - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Aug-2016
• Refers: ASTM E1316-16 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Feb-2016
• Refers: ASTM E1316-15a - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2015
• Refers: ASTM E1316-15 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Sep-2015
• Refers: ASTM E999-15 - Standard Guide for Controlling the Quality of Industrial Radiographic Film Processing
• Effective Date: 01-Jun-2015
• Refers: ASTM E1316-14 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2014
• Refers: ASTM E1316-14e1 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2014
• Refers: ASTM E1316-13d - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2013
• Refers: ASTM E1316-13c - Standard Terminology for Nondestructive Examinations
• Effective Date: 15-Jun-2013

Overview

ASTM E1114-20: Standard Test Method for Determining the Size of Iridium-192, Cobalt-60, and Selenium-75 Industrial Radiographic Sources is a key standard developed by ASTM International for non-destructive testing (NDT) applications involving gamma-emitting radiographic sources. The method provides procedures for accurately determining the physical size of Ir-192, Co-60, and Se-75 sources, which is critical for managing geometric unsharpness in industrial radiography. Accurate source size measurement enhances image quality and ensures compliance with industry requirements and regulatory guidelines.

Key Topics

• Geometric Unsharpness in Industrial Radiography:
  Geometric unsharpness impacts the clarity and quality of radiographic images. It depends on:
  • The size of the radiographic source
  • The distance between the source and the object
  • The distance between the object and the film or digital detector
• Measurement Method:
  This standard specifies:
  • Use of projection radiographs to image source and a reference sample
  • Comparison of dimensions on the radiograph for precise source size determination
  • Procedures for both film-based and digital detector systems, including criteria for system selection and measurement accuracy
• Units of Measurement:
  The standard recognizes both SI and inch-pound units. All measurements should be consistent within the selected unit system.
• Reporting Requirements:
  Detailed reporting is required, including source identification, test parameters, measurement data, and operator information.

Applications

Practical Uses in Non-Destructive Testing

• Industrial Radiography Quality Control:
  By determining the precise size of radioactive sources (Ir-192, Co-60, Se-75), NDT professionals can optimize source-to-object and object-to-film/detector distances to achieve the desired geometric unsharpness. This is essential for applications in:

  • Weld inspection in pipelines and pressure vessels
  • Evaluation of castings and forgings in aerospace and automotive parts
  • Quality control in construction and manufacturing industries

• Regulatory Compliance:
  Many NDT codes and standards require documented evidence of source size for audit and certification purposes. Using ASTM E1114-20 ensures traceable, standardized methods accepted internationally.

• Selection and Optimization of Radiographic Techniques:
  Knowledge of the source size enables technicians to select suitable film or digital imaging systems, adjust exposure parameters, and comply with project specifications.

Safety and Best Practices

• Ensuring Safe Work Environments:
  The standard highlights responsibilities for safety, health, and environmental practices, reminding users to evaluate and implement regulatory limitations before testing.
• Consistent Test Results:
  Standardized procedures help maintain consistent measurement results across different laboratories, improving reliability in NDT workflows.

Related Standards

For a comprehensive approach to industrial radiographic testing, several related standards should be considered alongside ASTM E1114-20:

• ASTM E999: Guide for Controlling the Quality of Industrial Radiographic Film Processing
• ASTM E1316: Terminology for Nondestructive Examinations
• ASTM E1815: Test Method for Classification of Film Systems for Industrial Radiography
• ASTM E2445: Practice for Performance Evaluation and Long-Term Stability of Computed Radiography Systems
• ASTM E2597: Practice for Manufacturing Characterization of Digital Detector Arrays
• ASTM E2002: Practice for Determining Total Image Unsharpness and Basic Spatial Resolution in Radiography and Radioscopy
• EN 12679: Industrial Radiography - Radiographic Method for the Determination of the Source Size for Radioisotopes

These standards ensure best practices for quality control, terminology, system classification, and digital imaging performance in industrial radiography.

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Keywords: source size, industrial radiography, Iridium-192, Cobalt-60, Selenium-75, ASTM E1114-20, non-destructive testing, geometric unsharpness, radiographic quality, NDT, radiographic sources, film radiography, digital detectors, quality control, international standards

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1114 − 20
Standard Test Method for
Determining the Size of Iridium-192, Cobalt-60, and
Selenium-75 Industrial Radiographic Sources
This standard is issued under the fixed designation E1114; 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 Industrial Radiography
E2445 Practice for Performance Evaluation and Long-Term
1.1 This test method covers the determination of the size of
Stability of Computed Radiography Systems
Iridium-192, Cobalt-60, and Selenium-75 radiographic
E2597 Practice for Manufacturing Characterization of Digi-
sources. The determination is based upon measurement of the
tal Detector Arrays
image of the source in a projection radiograph of the source
E2002 Practice for Determining Total Image Unsharpness
assembly and comparison to the measurement of the image of
and Basic Spatial Resolution in Radiography and Radios-
a reference sample in the same radiograph or the source guide
copy
tube.
2.2 Other International Standards:
1.2 Units—The values stated in either SI units or inch-
EN 12679:2018 Industrial Radiography—Radiographic
pound units are to be regarded separately as standard. The
Method for the Determination of the Source Size for
values stated in each system are not necessarily exact equiva-
Radioisotopes
lents; therefore, to ensure conformance with the standard, each
system shall be used independently of the other, and values
3. Terminology
from the two systems shall not be combined.
3.1 Fordefinitionsoftermsrelatingtothistestmethod,refer
1.3 This standard does not purport to address all of the
to Terminology E1316.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Significance and Use
priate safety, health, and environmental practices and deter-
4.1 One of the factors affecting the quality of a radiographic
mine the applicability of regulatory limitations prior to use.
image is geometric unsharpness. The degree of geometric
1.4 This international standard was developed in accor-
unsharpness is dependent upon the size of the source, the
dance with internationally recognized principles on standard-
distance between the source and the object to be radiographed,
ization established in the Decision on Principles for the
and the distance between the object to be radiographed and the
Development of International Standards, Guides and Recom-
film or digital detector. This test method allows the user to
mendations issued by the World Trade Organization Technical
determine the size of the source and to use this result to
Barriers to Trade (TBT) Committee.
establish source to object and object to film or detector
distances appropriate for maintaining the desired degree of
2. Referenced Documents
geometric unsharpness.
2.1 ASTM Standards:
NOTE 1—The European standard CEN EN 12579 describes a simplified
E999 Guide for Controlling the Quality of Industrial Radio-
procedure for measurement of source sizes of Ir-192, Co-60, and Se-75.
graphic Film Processing
TheresultingsourcesizeofIr-192iscomparabletotheresultsobtainedby
this test method.
E1316 Terminology for Nondestructive Examinations
E1815 Test Method for Classification of Film Systems for
5. Apparatus
5.1 Subjects are Iridium-192, Cobalt-60, and Selenium-75
This test method is under the jurisdiction of ASTM Committee E07 on
Sources where the source sizes are to be determined. The
Nondestructive Testing and is the direct responsibility of Subcommittee E07.01 on
appropriate apparatus and equipment for the safe storage,
Radiology (X and Gamma) Method.
Current edition approved Dec. 1, 2020. Published February 2021. Originally handling, and manipulation of the subject source, such as a
approved in 1986. Last previous edition approved in 2014 as E1114 – 09(2014).
radiographic exposure device (also referred to as a gamma ray
DOI: 10.1520/E1114-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1114 − 20
projector or gamma camera), remote control, source guide detector SNR > 100 shall be achieved. The measurement
tube, and source stop are also required. procedure of the SNR shall be in accordance with the proce-
dure of Practice E2597 for DDAs or Practice E2445 for
5.2 ReferenceSample(seeFigs.1-3)—Thereferencesample
imaging plate scanner systems.
for film radiography shall be of material which is not radioac-
tive.The recommended material is Iridium, Cobalt (also steel),
6. Procedure
or Selenium (also SeO ), respectively. However, substitutes
such as platinum, tungsten, or other material of similar
6.1 Set up the exposure arrangement as shown in Figs. 4-7.
radiopacity may be used. The sample should be of the same Position the X-ray tube directly over the center of the film or
geometricshapeasthesubjectsource,shouldbeapproximately
digital detector. The film or detector plane must be normal to
the same size as the subject source, and should be positioned the central ray of the X-ray beam. The X-ray spot should be
on or within a shim or envelope to simulate the source capsule
0.90 m (36 in.) from the film or detector. Position the reference
wall. The resulting radiographic contrast, with reference to sample and apparatus used to locate the subject source (source
adjacent background density of the image of the reference
stop) as close together as possible and directly over the center
sample,shouldbeapproximatelythesameasthatofthesubject of the film or detector. The plane of the source stop and
source. The actual dimensions of the reference sample should
reference sample must be parallel to the film or detector and
be determined to the nearest 0.025 mm (0.001 in.). If digital
normal to the central ray of the X-ray beam. The source stop
radiography and image processing is applied with imaging
and reference sample should be 0.15 m (6 in.) from the film or
plates or DDAs, the source guide can be used as reference
detector. The source stop should be connected to the radio-
sample for dimensional measurement.
graphic exposure device by the shortest source guide tube
practicable in order to minimize fogging of the film or detector
5.3 X-ray Generator, capable of producing a radiation
during source transit.
intensity (roentgen per hour at one metre / 39 in.) at least ten
times greater than that produced by the subject source. Ex-
6.2 Place identification markers to be imaged on the film or
amples of typical X-ray generator output requirements that
detector to identify, as a minimum, the identification (serial
satisfy this criterion are presented in Table 1.
number) of the subject source, the size of the reference sample,
the identification of the organization performing the
5.4 Film Systems—Only film systems having cognizant
determination, and the date of the determination. Care should
engineering organization approval or meeting the system class
be taken to ensure that the images of the subject source and
requirements ofTest Method E1815, for system classes I, II, or
reference sample will not be superimposed on the image of the
Special, shall be used. Selection of film systems should be
identification markers.
determined by such factors as the required radiographic quality
level, equipment capability, materials, and so forth. The film
6.3 Exposure—Select the X-ray tube potential (kV), X-ray
system selected shall be capable of demonstrating the required
tube current (mA), and exposure time such that the density in
image quality. No intensifying screens shall be used. Radio-
the image of the envelope surrounding the reference sample
graphic films shall be processed in accordance with Guide
does not exceed 3.0 and that the density difference between the
E999.
image of the reference sample and the image of the envelope
surrounding the reference sample is at least 0.10. In digital
5.5 Image Measurement Apparatus—This apparatus is used
images, the linear pixel value difference between the image of
to measure the size of the image of the spot. The apparatus
the reference sample and the image of the envelope surround-
shall be an optical comparator with built-in graticule (see 8.2
ing the reference sample shall be at least ten times larger than
for requirements).
the image noise σ (σ = standard deviation) of the pixel value
5.6 Digital Detectors—Digital detectors, which are either
fluctuations in an area of homogeneous exposure, measured in
imaging plates or digital detector arrays, may be used as film
a window (of at least 20 by 55 pixels) in a homogeneous
replacement. The digital detector shall possess a pixel pitch
neighbourhood area.
which is at least 40 times smaller than the nominal source size
NOTE 2—The actual parameters that will produce acceptable results
tomeasureandabasicspatialresolutionsmallerthan ⁄20ofthe
may vary between X-ray units, and trial exposures may be necessary.
nominalsourcesize.Thebasicspatialresolutionofthedetector
shall be measured in accordance with Practice E2002 (see an 6.3.1 Energize the X-ray generator and, at the same time,
example in 9.2), the procedure of Practice E2597 for DDAs or manipulate the subject source into the exposure position in the
Practice E2445 for the imaging plate scanner systems o
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1114 − 09 (Reapproved 2014) E1114 − 20
Standard Test Method for
Determining the Size of Iridium-192 Iridium-192, Cobalt-60,
and Selenium-75 Industrial Radiographic Sources
This standard is issued under the fixed designation E1114; 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
1.1 This test method covers the determination of the size of an Iridium-192 radiographic source.Iridium-192, Cobalt-60, and
Selenium-75 radiographic sources. The determination is based upon measurement of the image of the Iridium metal source in a
projection radiograph of the source assembly and comparison to the measurement of the image of a reference sample in the same
radiograph. radiograph or the source guide tube.
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in
each system mayare not benecessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be
used independently of the other. Combiningother, and values from the two systems may result in non-conformance with the
standard.shall not be combined.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E999 Guide for Controlling the Quality of Industrial Radiographic Film Processing
E1316 Terminology for Nondestructive Examinations
E1815 Test Method for Classification of Film Systems for Industrial Radiography
E2445 Practice for Performance Evaluation and Long-Term Stability of Computed Radiography Systems
E2597 Practice for Manufacturing Characterization of Digital Detector Arrays
This test method is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.01 on Radiology
(X and Gamma) Method.
Current edition approved Oct. 1, 2014Dec. 1, 2020. Published November 2014February 2021. Originally approved in 1986. Last previous edition approved in 20092014
ε1
as E1114 – 09 .(2014). DOI: 10.1520/E1114-09R14.10.1520/E1114-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1114 − 20
E2002 Practice for Determining Total Image Unsharpness and Basic Spatial Resolution in Radiography and Radioscopy
2.2 Other International Standards:
EN 12679:2000EN 12679:2018 Industrial Radiography—Radiographic Method for the Determination of the Source Size for
Radioisotopes
3. Terminology
3.1 For definitions of terms relating to this test method, refer to Terminology E1316.
4. Significance and Use
4.1 One of the factors affecting the quality of a radiographic image is geometric unsharpness. The degree of geometric unsharpness
is dependent upon the size of the source, the distance between the source and the object to be radiographed, and the distance
between the object to be radiographed and the film or digital detector. This test method allows the user to determine the size of
the source and to use this result to establish source to object and object to film or detector distances appropriate for maintaining
the desired degree of geometric unsharpness.
NOTE 1—The European standard CEN EN 12579 describes a simplified procedure for measurement of source sizes of Ir-192, Co-60Co-60, and Se-75.
The resulting source size of Ir-192 is comparable to the results obtained by this test method.
5. Apparatus
5.1 Subject Iridium-192 Source, Subjects are Iridium-192, Cobalt-60, and Selenium-75 Sources where the source size of which
is sizes are to be determined. The appropriate apparatus and equipment for the safe storage, handling, and manipulation of the
subject source, such as a radiographic exposure device (also referred to as a gamma ray projector or gamma camera), remote
control, source guide tube, and source stop are also required.
5.2 Reference Sample (see Figs. 1-3)—The reference sample for film radiography shall be of material which is not radioactive. The
recommended material is Iridium. Iridium, Cobalt (also steel), or Selenium (also SeO ), respectively. However, substitutes such
as platinum, tungsten, or other material of similar radiopacity may be used. The sample should be of the same geometric shape
as the subject source, should be approximately the same size as the subject source, and should be positioned on or within a shim
or envelope to simulate the source capsule wall. The resulting radiographic contrast, with reference to adjacent background density
of the image of the reference sample, should be approximately the same as that of the subject source. The actual dimensions of
the reference sample should be determined to the nearest 0.025 mm (0.001 in.). If digital radiography and image processing is
applied with imaging plates or DDAs, the source guide can be used as reference sample for dimensional measurement.
5.3 X-ray Generator, capable of producing a radiation intensity (roentgen per hour at one metre) metre / 39 in.) at least ten times
greater than that produced by the subject source. Examples of typical X-ray generator output requirements that satisfy this criterion
are presented in Table 1.
5.4 Film systems—Systems—Only film systems having cognizant engineering organization approval or meeting the system class
requirements of Test Method E1815, for system classes I, II, or Special, shall be used. Selection of film systems should be
determined by such factors as the required radiographic quality level, equipment capability, materials, and so forth. The film system
selected shall be capable of demonstrating the required image quality. No intensifying screens shall be used. Radiographic Radio-
graphic films shall be processed in accordance with Guide E999.
FIG. 1 Reference Sample in Standard Source Encapsulation
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
E1114 − 20
FIG. 2 Alternate Reference Sample Arrangement
FIG. 3 Alternate Reference Sample Arrangement
TABLE 1 Examples of Typical X-ray Generator Output
Requirements for Related Iridium Source Activities
Subject Iridium Source Typical X-ray Generator
Radiation Output Requirements
Activity Output
Potential Current
(Curie) (R/h at 1 m)
30 14.4 160 kV 5 mA
or 200 kV 3 mA
100 48.0 160 kV 10 mA
or 250 kV 4 mA
200 96.0 160 kV 20 mA
or 250 kV 8 mA
or 300 kV 6 mA
5.5 Image Measurement Apparatus—This apparatus is used to measure the size of the image of the spot. The apparatus shall be
an optical comparator with built-in graticule with 0.1(see 8.2 mm divisions or 0.001 in. divisions and magnification of 5× to
10×.for requirements).
5.6 Digital Detectors—Digital detectors, which are either imaging plates or digital detector arrays, may be used as film
replacement. The digital detector shall possess a pixel pitch which is at least 40 times smaller than the nominal source size to
measure and a basic spatial resolution smaller than ⁄20 of the nominal source size. The basic spatial resolution of the detector shall
be measured in accordance with Practice E2002 (see an example in 9.2), the procedure of Practice E2597 for DDAs or Practice
E2445 for the imaging plate scanner systemsystems or taken from manufacturer statements. In the area of free beam a detector
SNR > 100 shall be achieved. The measurement procedure of the SNR shall be in accordance with the procedure of Practice
D
E2597 for DDAs or Practice E2445 for the imaging plate scanner system.systems.
5.7 Evaluation of Digital Images—Digital images shall be evaluated by an image processing software with contrast, brightness,
profile and zoom function. The digital images shall be magnified at the monitor to a degree that allows the image viewing with
at least one pixel of the image at one pixel of the monitor.
6. Procedure
6.1 Set up the exposure arrangement as shown in Figs. 4-7. Position the X-ray tube directly over the center of the film or digital
detector. The film or detector plane must be normal to the central ray of the X-ray beam. The X-ray spot should be 0.90 m (36
E1114 − 20
FIG. 4 Typical Exposure Arrangement
FIG. 5 Typical Arrangement Using a Specially Designed Guide Tube
FIG. 6 Typical Arrangement Using a Standard Guide Tube and Special Positioning Fixture
in.) from the film or detector. Position the reference sample and apparatus used to locate the subject source (source stop) as close
together as possible and directly over the center of the film or detector. The plane of the source stop and reference sample must
be parallel to the film or detector and normal to the central ray of the X-ray beam. The source stop and reference sample should
be 0.15 m (6 in.) from the film or detector. The source stop should be connected to the radiographic exposure device by the shortest
source guide tube practicable in order to minimize fogging of the film or detector during source transit.
E1114 − 20
FIG. 7 Typical Arrangement Using Reference Sample Positioning Device
6.2 Place identification markers to be imaged on the film or detector to identify, as a minimum, the identification (serial number)
of the subject source, the size of the reference sample, the identification of the organization performing the determination, and the
date of the determination. Care should be taken to ensure that the images of the subject source and reference sample will not be
superimposed on the image of the identification markers.
6.3 Exposure—Select the X-ray tube potential (kV), X-ray tube current (mA)(mA), and exposure time such that the density in the
image of the envelope surrounding the reference sample does not exceed 3.0 and that the density difference between the image
of the reference sample and the image of the envelope surrounding the reference sample is at least 0.10. In digital images, the linear
greypixel value difference between the image of the reference sample and the image of the envelope surrounding the reference
sample shall be five at least ten times larger than the image noise σ(σ σ (σ = standard deviationdeviation) of the greypixel value
fluctuations in an area of homogeneous exposure, measured in a window of(of at least 20 by 55 pixels) in a homogeneous
neighborneighbourhood area.
NOTE 2—The actual parameters that will produce acceptable results may vary between X-ray units, and trial exposures ma
...