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ASTM E1441-00

(Guide)

Standard Guide for Computed Tomography (CT) Imaging

Standard Guide for Computed Tomography (CT) Imaging

SCOPE
1.1 Computed tomography (CT) is a radiographic method that provides an ideal examination technique whenever the primary goal is to locate and size planar and volumetric detail in three dimensions. Because of the relatively good penetrability of X rays, as well as the sensitivity of absorption cross sections to atomic chemistry, CT permits the nondestructive physical and, to a limited extent, chemical characterization of the internal structure of materials. Also, since the method is X-ray based, it applies equally well to metallic and non-metallic specimens, solid and fibrous materials, and smooth and irregularly surfaced objects. When used in conjunction with other nondestructive evaluation (NDE) methods, such as ultrasound, CT data can provide evaluations of material integrity that cannot currently be provided nondestructively by any other means.  
1.2 This guide is intended to satisfy two general needs for users of industrial CT equipment: (1) the need for a tutorial guide addressing the general principles of X-ray CT as they apply to industrial imaging; and (2) the need for a consistent set of CT performance parameter definitions, including how these performance parameters relate to CT system specifications. Potential users and buyers, as well as experienced CT inspectors, will find this guide a useful source of information for determining the suitability of CT for particular examination problems, for predicting CT system performance in new situations, and for developing and prescribing new scan procedures.  
1.3 This guide does not specify test objects and test procedures for comparing the relative performance of different CT systems; nor does it treat CT inspection techniques, such as the best selection of scan parameters, the preferred implementation of scan procedures, the analysis of image data to extract densitometric information, or the establishment of accept/reject criteria for a new object.  
1.4 Standard practices and methods are not within the purview of this guide. The reader is advised, however, that examination practices are generally part and application specific, and industrial CT usage is new enough that in many instances a consensus has not yet emerged. The situation is complicated further by the fact that CT system hardware and performance capabilities are still undergoing significant evolution and improvement. Consequently, an attempt to address generic examination procedures is eschewed in favor of providing a thorough treatment of the principles by which examination methods can be developed or existing ones revised.  
1.5 The principal advantage of CT is that it nondestructively provides quantitative densitometric (that is, density and geometry) images of thin cross sections through an object. Because of the absence of structural noise from detail outside the thin plane of inspection, images are much easier to interpret than conventional radiographic data. The new user can learn quickly (often upon first exposure to the technology) to read CT data because the images correspond more closely to the way the human mind visualizes three- dimensional structures than conventional projection radiography. Further, because CT images are digital, they may be enhanced, analyzed, compressed, archived, input as data into performance calculations, compared with digital data from other NDE modalities, or transmitted to other locations for remote viewing. Additionally, CT images exhibit enhanced contrast discrimination over compact areas larger than 20 to 25 pixels. This capability has no classical analog. Contrast discrimination of better than 0.1% at three-sigma confidence levels over areas as small as one-fifth of one percent the size of the object of interest are common.  
1.6 With proper calibration, dimensional inspections and absolute density determinations can also be made very accurately. Dimensionally, virtually all CT systems provide a pixel resolution of roughly 1 part in 1000 (since,...

General Information

Status
Historical
Publication Date
09-Jul-2000
ICS
35.240.80 - IT applications in health care technology
Technical Committee
E07 - Nondestructive Testing
Drafting Committee
E07.01 - Radiology (X and Gamma) Method
Current Stage
Ref Project

Relations

Replaced By
ASTM E1441-00(2005) - Standard Guide for Computed Tomography (CT) Imaging
Effective Date
01-Dec-2005
Referred By
ASTM F2902-16e1 - Standard Guide for Assessment of Absorbable Polymeric Implants
Effective Date
10-Jul-2000
Referred By
ASTM D8093-19 - Standard Guide for Nondestructive Evaluation of Nuclear Grade Graphite
Effective Date
10-Jul-2000
Referred By
ASTM E3375-23 - Standard Practice for Cone Beam Computed Tomographic (CT) Examination
Effective Date
10-Jul-2000
Referred By
ASTM E1814-14(2022) - Standard Practice for Computed Tomographic (CT) Examination of Castings
Effective Date
10-Jul-2000
Referred By
ASTM E2533-21 - Standard Guide for Nondestructive Examination of Polymer Matrix Composites Used in Aerospace Applications
Effective Date
10-Jul-2000
Referred By
ASTM E1695-20e1 - Standard Test Method for Measurement of Computed Tomography (CT) System Performance
Effective Date
10-Jul-2000
Referred By
ASTM E2767-21 - Standard Practice for Digital Imaging and Communication in Nondestructive Evaluation (DICONDE) for X-ray Computed Tomography (CT) Test Methods
Effective Date
10-Jul-2000
Referred By
ASTM F2450-18 - Standard Guide for Assessing Microstructure of Polymeric Scaffolds for Use in Tissue-Engineered Medical Products
Effective Date
10-Jul-2000
Referred By
ASTM E1817-08(2022) - Standard Practice for Controlling Quality of Radiological Examination by Using Representative Quality Indicators (RQIs)
Effective Date
10-Jul-2000
Referred By
ASTM E1931-16(2022) - Standard Guide for Non-computed X-Ray Compton Scatter Tomography
Effective Date
10-Jul-2000
Referred By
ASTM F3160-21 - Standard Guide for Metallurgical Characterization of Absorbable Metallic Materials for Medical Implants
Effective Date
10-Jul-2000
Referred By
ASTM E1672-12(2020) - Standard Guide for Computed Tomography (CT) System Selection
Effective Date
10-Jul-2000
Referred By
ASTM E543-21 - Standard Specification for Agencies Performing Nondestructive Testing
Effective Date
10-Jul-2000
Referred By
ASTM E1935-97(2019) - Standard Test Method for Calibrating and Measuring CT Density
Effective Date
10-Jul-2000

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ASTM E1441-00 - Standard Guide for Computed Tomography (CT) Imaging
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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 1441 – 00
Standard Guide for
1
Computed Tomography (CT) Imaging
This standard is issued under the fixed designation E1441; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope cific, and industrial CT usage is new enough that in many
instances a consensus has not yet emerged. The situation is
1.1 Computed tomography (CT) is a radiographic method
complicated further by the fact that CT system hardware and
that provides an ideal examination technique whenever the
performance capabilities are still undergoing significant evo-
primary goal is to locate and size planar and volumetric detail
lution and improvement. Consequently, an attempt to address
in three dimensions. Because of the relatively good penetra-
generic examination procedures is eschewed in favor of
bility of X rays, as well as the sensitivity of absorption cross
providing a thorough treatment of the principles by which
sections to atomic chemistry, CT permits the nondestructive
examination methods can be developed or existing ones
physical and, to a limited extent, chemical characterization of
revised.
the internal structure of materials. Also, since the method is
1.5 TheprincipaladvantageofCTisthatitnondestructively
X-ray based, it applies equally well to metallic and non-
provides quantitative densitometric (that is, density and geom-
metallic specimens, solid and fibrous materials, and smooth
etry) images of thin cross sections through an object. Because
and irregularly surfaced objects. When used in conjunction
of the absence of structural noise from detail outside the thin
with other nondestructive evaluation (NDE) methods, such as
plane of inspection, images are much easier to interpret than
ultrasound, CT data can provide evaluations of material integ-
conventionalradiographicdata.Thenewusercanlearnquickly
rity that cannot currently be provided nondestructively by any
(often upon first exposure to the technology) to read CT data
other means.
because the images correspond more closely to the way the
1.2 This guide is intended to satisfy two general needs for
human mind visualizes three-dimensional structures than con-
users of industrial CT equipment: (1) the need for a tutorial
ventional projection radiography. Further, because CT images
guide addressing the general principles of X-ray CT as they
are digital, they may be enhanced, analyzed, compressed,
applytoindustrialimaging;and(2)theneedforaconsistentset
archived, input as data into performance calculations, com-
of CT performance parameter definitions, including how these
pared with digital data from other NDE modalities, or trans-
performance parameters relate to CT system specifications.
mitted to other locations for remote viewing.Additionally, CT
Potential users and buyers, as well as experienced CT inspec-
images exhibit enhanced contrast discrimination over compact
tors, will find this guide a useful source of information for
areas larger than 20 to 25 pixels. This capability has no
determining the suitability of CT for particular examination
classicalanalog.Contrastdiscriminationofbetterthan0.1%at
problems, for predicting CT system performance in new
three-sigma confidence levels over areas as small as one-fifth
situations, and for developing and prescribing new scan pro-
of one percent the size of the object of interest are common.
cedures.
1.6 With proper calibration, dimensional inspections and
1.3 This guide does not specify test objects and test proce-
absolute density determinations can also be made very accu-
dures for comparing the relative performance of different CT
rately. Dimensionally, virtually all CT systems provide a pixel
systems;nordoesittreatCTinspectiontechniques,suchasthe
resolution of roughly 1 part in 1000 (since, at present,
bestselectionofscanparameters,thepreferredimplementation
1024 31024 images are the norm), and metrological algo-
of scan procedures, the analysis of image data to extract
rithms can often measure dimensions to one-tenth of one pixel
densitometricinformation,ortheestablishmentofaccept/reject
or so with three-sigma accuracies. For small objects (less than
criteria for a new object.
4 in. in diameter), this translates into accuracies of approxi-
1.4 Standard practices and methods are not within the
mately 0.1 mm (0.003 to 0.005 in.) at three-sigma. For much
purview of this guide. The reader is advised, however, that
larger objects, the corresponding figure will be proportionally
examination practices are generally part and application spe-
greater. Attenuation values can also be related accurately to
material densities. If
...

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SIGNIFICANCE AND USE
5.1 This test method allows specification of the density calibration procedures to be used to calibrate and perform material density measurements using CT image data. Such measurements can be used to evaluate parts, characterize a particular system, or compare different systems, provided that observed variations are dominated by true changes in object density rather than by image artifacts. The specified procedure may also be used to determine the effective X-ray energy of a CT system.  
5.2 The recommended test method is more accurate and less susceptible to errors than alternative CT-based approaches, because it takes into account the effective energy of the CT system and the energy-dependent effects of the X-ray attenuation process.
FIG. 1 Density Calibration Phantom  
5.3 This (or any) test method for measuring density is valid only to the extent that observed CT-number variations are reflective of true changes in object density rather than image artifacts. Artifacts are always present at some level and can masquerade as density variations. Beam hardening artifacts are particularly detrimental. It is the responsibility of the user to determine or establish, or both, the validity of the density measurements; that is, they are performed in regions of the image which are not overly influenced by artifacts.  
5.4 Linear attenuation and mass attenuation may be measured in various ways. For a discussion of attenuation and attenuation measurement, see Guide E1441 and Practice E1570.
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1.2 CT provides an excellent method of nondestructively measuring density variations, which would be very difficult to quantify otherwise. Density is inherently a volumetric property of matter. As the measurement volume shrinks, local material inhomogeneities become more important; and measured values will begin to vary about the bulk density value of the material.  
1.3 All values are stated in SI units.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
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5.1 Computed tomography (CT) is a radiographic reconstruction method that provides a sensitive technique whenever the primary goal is to locate and size planar and volumetric detail in three dimensions.  
5.2 CT provides quantitative volume images as a function of density and element number (attenuation coefficient) by means of computer-processed combinations of many X-ray measurements taken from different angles to produce cross-sectional images of specific areas of a scanned object, allowing the user to see inside the object without cutting. CT is considered much easier to interpret than conventional radiographic data due to the elimination of overlapping structures. The new user can learn quickly to read CT data because the images correspond more closely to the way the human mind visualizes three-dimensional structures than conventional projection radiography. Further, because CT slices and volumes are digital, they may be enhanced, analyzed, compressed, archived, input as data into performance calculations, compared with digital data from other NDE modalities, or transmitted to other locations for remote viewing.
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1.1 CT is a radiographic examination technique that generates digital images in three dimensions of an object, including the interior structure. Because of the relatively good penetrability of X-rays, CT permits the nondestructive physical and, to a limited extent, chemical characterization of the internal structure of materials. Also, since the method is X-ray based, it applies equally well to metallic and non-metallic specimens, solid and fibrous materials, and smooth and irregularly surfaced objects.  
1.2 This guide is intended to satisfy two general needs for users of industrial CT equipment: (1) the need for a tutorial guide addressing the general principles of X-ray CT as they apply to industrial imaging; and (2) the need for a consistent set of CT performance parameter definitions, including how these performance parameters relate to CT system specifications.  
1.3 This guide does not specify CT examination techniques, such as the best selection of scan parameters, the preferred implementation of scan procedures, or the establishment of accept/reject criteria for a new object.  
1.4 Units—No units are mentioned in this document. However, for CT, values are typically stated in SI units and are regarded as standard.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

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ASTM
ASTM E3398-23(Guide)
Standard Guide for Digital Neutron Radiography

SIGNIFICANCE AND USE
4.1 Purpose—Practices to be employed for the radiographic examination of materials and components with neutrons using digital neutron detectors are outlined herein. They are intended as a guide for the assessment of a digital neutron radiograph’s characteristics. For information on neutron beam lines for imaging and film neutron radiography, refer to Guide E748.  
4.2 Limitations—Acceptance standards have not been established for any material or production process. Neutron radiography, whether performed by means of a reactor, an accelerator, subcritical assembly, or radioactive source, will be consistent in sensitivity and spatial resolution only if the consistency of all details of the technique, such as neutron source, collimation, geometry, imaging system, etc., are maintained. This guide is limited to the use of digital neutron detectors in combination with neutron conversion materials for image recording. This guide is intended for use with thermal and cold neutron spectrums. The production of thermal neutron radiographs by employing the use of film and appropriate conversion screens is covered in Guide E748.  
4.3 Interpretation and Acceptance Standards—Interpretat- ion and acceptance standards are not covered by this guide. Designation of accept-reject standards is recognized to be within the cognizance of product specifications.  
4.4 Other Aspects of the Neutron Radiographic Process—For many important aspects of neutron radiography such as technique, files, viewing of radiographs, storage of radiographs, film processing, and record keeping, refer to Guide E94, which covers these aspects for X-ray radiography. (See Section 2.)
SCOPE
1.1 This guide covers the evaluation, qualification, and quantification of digital neutron images. These images can be acquired by many methods, including: neutron sensitive imaging plates (Computed Radiography – CR), Digital Detector Arrays – DDA’s (amorphous silicon, CMOS, CCD, etc.), micro-channel plates, neutron sensitive fluoroscopes, neutron sensitive scintillators coupled to optical cameras, digitized radiographic films, and linear diode arrays.  
1.2 This guide does not purport to establish what is considered an acceptable image but is intended to only give guidance on digital neutron imaging, as well as image quality metrics of importance, and how they can be measured and reported.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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.

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ASTM
ASTM E2699-23(Practice)
Standard Practice for Digital Imaging and Communication in Nondestructive Evaluation (DICONDE) for Digital X-ray (DX) Test Methods

SIGNIFICANCE AND USE
5.1 Personnel that are responsible for the creation, transfer, and storage of digital X-ray test results will use this standard. This practice defines a set of information modules that, along with Practice E2339 and the DICOM standard, provides a standard means to organize digital X-ray test parameters and results. The digital X-ray test results may be displayed and analyzed on any device that conforms to this standard. Personnel wishing to view any digital X-ray inspection data stored according to Practice E2339 may use this document to help them decode and display the data contained in the DICONDE-compliant inspection record.
SCOPE
1.1 This practice covers the interoperability of digital X-ray imaging equipment using Digital Detector Arrays (DDA) as described in Practice E2698 by specifying image data transfer and archival methods in commonly accepted terms. A separate practice, Practice E2738, addresses this topic for digital X-ray imaging equipment using Computed Radiography (CR). This document is intended to be used in conjunction with Practice E2339 on Digital Imaging and Communication in Nondestructive Evaluation (DICONDE). Practice E2339 defines an industrial adaptation of DICOM NEMA PS3 / ISO 12052 (DICOM, see http://medical.nema.org), an international standard for image data acquisition, review, storage, and archival storage. The goal of Practice E2339, commonly referred to as DICONDE, is to provide a standard that facilitates the display and analysis of NDE results on any system conforming to the DICONDE standard. Toward that end, Practice E2339 provides a data dictionary and a set of information modules that are applicable to all NDE modalities. This practice supplements Practice E2339 by providing information object definitions, information modules, and a data dictionary that are specific to digital X-ray test methods.  
1.2 This practice has been developed to overcome the issues that arise when analyzing or archiving data from digital X-ray test equipment using proprietary data transfer and storage methods. As digital technologies evolve, data must remain decipherable through the use of open, industry-wide methods for data transfer and archival storage. This practice defines a method where all the digital X-ray technique parameters and test results are communicated and stored in a standard manner regardless of changes in digital technology.  
1.3 This practice does not specify:  
1.3.1 A testing or validation procedure to assess an implementation's conformance to the standard.  
1.3.2 The implementation details of any features of the standard on a device claiming conformance.  
1.3.3 The overall set of features and functions to be expected from a system implemented by integrating a group of devices each claiming DICONDE conformance.  
1.4 Units—Although this practice contains no values that require units, it does describe methods to store and communicate data that do require units to be properly interpreted. The SI units required by this practice are to be regarded as standard. No other units of measurement are included in this standard.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

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ASTM
ASTM E2738-23(Practice)
Standard Practice for Digital Imaging and Communication in Nondestructive Evaluation (DICONDE) for Computed Radiography (CR) Test Methods

SIGNIFICANCE AND USE
5.1 Personnel that are responsible for the creation, transfer, and storage of computed radiography NDE data will use this practice. This practice will define a set of information modules that along with the Practice E2339 and the DICOM standard will provide a standard means to organize CR inspection data. The CR inspection data may be displayed and analyzed on any device that conforms to the standard. Personnel wishing to view any CR inspection data stored in accordance with Practice E2339 may use this practice to help them decode and display the data contained in the DICONDE compliant inspection record.
SCOPE
1.1 This practice covers the interoperability of computed radiography (CR) imaging and data acquisition equipment by specifying image data transfer and archival storage methods in commonly accepted terms. This practice is intended to be used in conjunction with Practice E2339 on Digital Imaging and Communication in Nondestructive Evaluation (DICONDE). Practice E2339 defines an industrial adaptation of NEMA PS3 / ISO 12052 (DICOM, see http://medical.nema.org), an international standard for image data acquisition, review, storage, and archival storage. The goal of Practice E2339, commonly referred to as DICONDE, is to provide a standard that facilitates the display and analysis of NDE results on any system conforming to the DICONDE standard. Toward that end, Practice E2339 provides a data dictionary and a set of information modules that are applicable to all NDE modalities. This practice supplements Practice E2339 by providing information object definitions, information modules and a data dictionary that are specific to computed radiography test methods.  
1.2 This practice has been developed to overcome the issues that arise when analyzing or archiving data from CR test equipment using proprietary data transfer and storage methods. As digital technologies evolve, data must remain decipherable through the use of open, industry-wide methods for data transfer and archival storage. This practice defines a method where all standard CR technique parameters and test results are communicated and stored in a standard manner regardless of changes in digital technology.  
1.3 This practice does not specify:  
1.3.1 A testing or validation procedure to assess an implementation's conformance to the standard.  
1.3.2 The implementation details of any features of the standard on a device claiming conformance.  
1.3.3 The overall set of features and functions to be expected from a system implemented by integrating a group of devices each claiming DICONDE conformance.  
1.4 Although this practice contains no values that require units, it does describe methods to store and communicate data that do require units to be properly interpreted. The SI units required by this practice are to be regarded as standard. No other units of measurement are included in this practice.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

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