ASTM E1079-21

Standard Practice for Calibration of Transmission Densitometers

SIGNIFICANCE AND USE
4.1 This practice provides a means for calibrating transmission densitometers used for the measurement of diffuse optical density on radiographic films. A transmission densitometer calibrated in accordance with this practice provides the assurance that accurate optical density values of radiographs are obtained.
SCOPE
1.1 This practice2 covers the calibration of transmission densitometers used to perform measurements of diffuse optical density on radiographic films (see Note 1).  
1.2 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.
Note 1: For further information on the design and use of densitometers, the following literature is suggested as additional background information: ISO 5–1:2009, ISO 5–2:2009, ISO 5–3:2009, and ISO 14807:2001.  
1.3 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: 31-Oct-2021
• ICS: 17.180.30 - Optical measuring instruments
• 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 E1316-14e1 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2014
• Refers: ASTM E1316-14 - 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
• Refers: ASTM E1316-13b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2013

Overview

ASTM E1079-21 - Standard Practice for Calibration of Transmission Densitometers - establishes procedures for the calibration and periodic verification of transmission densitometers used to measure the diffuse optical density of radiographic films. This practice is essential in ensuring the accuracy and reliability of optical density readings, which are critical for radiographic quality control and compliance with industry requirements. By following ASTM E1079-21, organizations can maintain consistent measurement standards and meet audit or regulatory expectations for nondestructive testing and film quality assurance.

Key Topics

• Transmission Densitometer Calibration: Details the use of calibrated step tablets, including those traceable to NIST or compliant with applicable ISO or ANSI standards, for densitometer calibration.
• Optical Density Measurement: Focuses on accurate measurement of diffuse optical density in radiographic films, supporting correct interpretation of film results.
• Periodic Verification: Outlines requirements for ongoing verification checks to assure continued performance, including frequency (at minimum once per shift or after specific operational events).
• Traceability and Documentation: Emphasizes proper record-keeping of all calibration and verification activities, including identification of equipment and personnel.
• Equipment Maintenance: Requires regular replacement or recertification of step tablets and recalibration after densitometer repairs or incidents such as dropping.

Applications

The ASTM E1079-21 standard is applicable in various sectors where radiographic films are pivotal for nondestructive examination and quality assurance. Common applications include:

• Industrial Radiography: Ensures accurate density readings for film-based radiography in sectors such as aerospace, construction, and manufacturing.
• Quality Control Labs: Provides a standardized approach for calibration of transmission densitometers used in film assessment and validation processes.
• Regulatory Compliance: Supports adherence to industry and customer requirements for film imaging processes, especially where traceable calibrations are mandated (including ASME Code environments).
• Service Providers: Used by calibration and maintenance services handling testing equipment for radiographic inspections.

Practically, the standard gives confidence that optical density measurements are reliable, traceable, and support regulatory or contractual obligations.

Related Standards

Organizations implementing ASTM E1079-21 should also be aware of these related standards and guidelines:

• ASTM E1316 - Terminology for Nondestructive Examinations: Provides relevant definitions for terms referenced in E1079-21.
• ISO 5-1:2009 - Photography and Graphic Technology – Density Measurements – Part 1: Geometry and Functional Notation
• ISO 5-2:2009 - Density Measurements – Part 2: Geometric Conditions for Transmittance Density
• ISO 5-3:2009 - Density Measurements – Part 3: Spectral Conditions
• ISO 14807:2001 - Transmission and Reflection Densitometers – Method for Determining Performance
• ASME Boiler and Pressure Vessel Code Practice SE-1079: For specific applications involving pressure equipment inspections.

Conclusion

Implementing ASTM E1079-21 helps organizations ensure their transmission densitometers are calibrated to deliver accurate, reliable optical density measurements on radiographic films. With clear processes for calibration, verification, traceability, and documentation, this standard is a crucial tool for maintaining high-quality nondestructive testing results and meeting industry best practices and regulatory expectations.

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: E1079 − 21
Standard Practice for
Calibration of Transmission Densitometers
This standard is issued under the fixed designation E1079; 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 ISO 5–3:2009 Photography and Graphic Technology —
Density Measurements — Part 3: Spectral Conditions
1.1 This practice covers the calibration of transmission
ISO 14807:2001 Photography — Transmission and Reflec-
densitometers used to perform measurements of diffuse optical
tion Densitometers — Method for Determining Perfor-
density on radiographic films (see Note 1).
mance
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 Definitions—For definitions of terms used in this
priate safety, health, and environmental practices and deter-
practice, see Terminology E1316.
mine the applicability of regulatory limitations prior to use.
NOTE 1—For further information on the design and use of
4. Significance and Use
densitometers, the following literature is suggested as additional back-
ground information: ISO 5–1:2009, ISO 5–2:2009, ISO 5–3:2009, and
4.1 This practice provides a means for calibrating transmis-
ISO 14807:2001.
sion densitometers used for the measurement of diffuse optical
1.3 This international standard was developed in accor-
density on radiographic films. A transmission densitometer
dance with internationally recognized principles on standard- calibrated in accordance with this practice provides the assur-
ization established in the Decision on Principles for the
ance that accurate optical density values of radiographs are
Development of International Standards, Guides and Recom- obtained.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
5. Apparatus
5.1 Apparatus should consist of the following:
2. Referenced Documents
5.1.1 A calibrated step tablet covering the optical density
2.1 ASTM Standards:
range used in production radiographs shall be used. The step
E1316 Terminology for Nondestructive Examinations
tablet may be a NIST X-ray Step Tablet (X-Ray Film Step
4 5
2.2 ISO Standards: Tablet Transmission Density Standard 38100C) , or alternately
ISO 5–1:2009 Photography and Graphic Technology — a step tablet from another supplier that is traceable to the NIST
Density Measurements — Part 1: Geometry and Func- steptabletintherangeprovidedbyNISTcertification.Thestep
tional Notation tablet shall have at least five steps with optical densities, which
ISO 5–2:2009 Photography and Graphic Technology — cover the optical density range that is used for production
Density Measurements — Part 2: Geometric Conditions radiographs.Acalibration certificate shall be provided with the
for Transmittance Density step tablet indicating the tablet ID and recorded values for the
optical density of each step. For suppliers of step tablets other
than NIST, the certificate shall indicate conformance of trace-
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- ability to NIST, applicable ISO or ANSI standards (for
structive Testing and is the direct responsibility of Subcommittee E07.01 on
example, ISO 5–3) used, verification of measurement on a
Radiology (X and Gamma) Method.
NIST step tablet, the ID number of the step tablet, and
Current edition approved Nov. 1, 2021. Published November 2021. Originally
calibration date of the step tablet. Precautions should be taken
approved in 1985. Last previous edition approved in 2016 as E1079 – 16. DOI:
10.1520/E1079-21.
in the storage, handling, and use of the step tablet. In the event
For ASME Boiler and Pressure Vessel Code applications, see related Practice
it becomes scratched, blemished, or exhibits other signs of
SE-1079 in Section II of that Code.
deleterious wear, it should be replaced immediately. The NIST
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.
4 5
Available from American National Standards Institute (ANSI), 25 W. 43rd St., Available from National Institute of Standards and Technology (NIST), 100
4th Floor, New York, NY 10036. Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1079 − 21
(or alternate, if used) step tablet shall be replaced or recali- beginning of each shift, after 8 h of continuous operation, or
brated four years from the date of first use. change of apertures, whichever occurs first.
5.1.2 Transmission Densitometers, with either d
...

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: E1079 − 16 E1079 − 21
Standard Practice for
Calibration of Transmission Densitometers
This standard is issued under the fixed designation E1079; 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 practice covers the calibration of transmission densitometers used to perform radiographic film density measurements
measurements of diffuse optical density on radiographic films (see Note 1).
1.2 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.
NOTE 1—For further information on the design and use of densitometers, the following literature is suggested as additional background information:
ISO 5–1:2009, ISO 5–2:2009, ISO 5–3:2009, and ISO 14807:2001.
1.3 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:
E1316 Terminology for Nondestructive Examinations
2.2 ISO Standards:
ISO 5–1:2009 Photography and Graphic Technology — Density Measurements — Part 1: Geometry and Functional Notation
ISO 5–2:2009 Photography and Graphic Technology — Density Measurements — Part 2: Geometric Conditions for
Transmittance Density
ISO 5–3:2009 Photography and Graphic Technology -— Density Measurements -— Part 3: Spectral Conditions
ISO 14807:2001 Photography -— Transmission and Reflection Densitometers -— Method for Determining Performance
3. Terminology
3.1 Definitions—For definitions of terms used in this practice, see Terminology E1316.
4. Significance and Use
4.1 This practice provides a means for calibrating transmission densitometers used for the measurement of radiographic film
This practice 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 June 1, 2016Nov. 1, 2021. Published June 2016November 2021. Originally approved in 1985. Last previous edition approved in 20102016 as
E1079 - 10.E1079 – 16. DOI: 10.1520/E1079-16.10.1520/E1079-21.
For ASME Boiler and Pressure Vessel Code applications, see related Practice SE-1079 in Section II of that Code.
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.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1079 − 21
density. diffuse optical density on radiographic films. A transmission densitometer calibrated in accordance with this practice
provides the assurance that accurate optical density values of radiographs are obtained.
5. Apparatus
5.1 Apparatus should consist of the following:
5.1.1 A calibrated step tablet covering the optical density range used in production radiographs shall be used. The step tablet may
be a NIST X-ray Step Tablet (X-Ray Film Step Tablet Transmission Density Standard 38100C) , or alternately a step tablet from
another supplier that is traceable to the NIST step tablet in the range provided by NIST certification. The step tablet shall have at
least five step steps with optical densities, which cover the optical density range that is used for production radiographs. A
calibration certificate shall be provided with the step tablet indicating the tablet ID and recorded values for each step density. the
optical density of each step. For suppliers of step tablets other than NIST, the certificate shall indicate conformance of traceability
to NIST, applicable ISO or ANSI standards (for example, ISO 5–3) used, verification of measurement on a NIST step tablet, the
ID number of the step tablet, and calibration date of the step tablet. Precautions should be taken in the storage, handling, and use
of the step tablet. In the event it becomes scratched, blemished, or exhibits other signs of deleterious wear, it should be replaced
immediately. The NIST (or alternate, if used) step tablet shall be replaced or recalibrated four years from the date of first use.
5.1.2 Transmission Densitometers, with either direct-scale readout or digital readout displays specifically manufactured for the
purpose of measuring the range of filmoptical densities of films described in 5.1.1 may be used.
5.1.3 Manufacturer’s Operating Instructions for App
...