ASTM E1672-12
(Guide)Standard Guide for Computed Tomography (CT) System Selection
Standard Guide for Computed Tomography (CT) System Selection
SIGNIFICANCE AND USE
This guide will aid the purchaser in generating a CT system specification. This guide covers the conversion of purchaser's requirements to system components that must occur for a useful CT system specification to be prepared.
Additional information can be gained in discussions with potential suppliers or with independent consultants.
This guide is applicable to purchasers seeking scan services.
This guide is applicable to purchasers needing to procure a CT system for a specific examination application.
SCOPE
1.1 This guide covers guidelines for translating application requirements into computed tomography (CT) system requirements/specifications and establishes a common terminology to guide both purchaser and supplier in the CT system selection process. This guide is applicable to the purchaser of both CT systems and scan services. Computed tomography systems are complex instruments, consisting of many components that must correctly interact in order to yield images that repeatedly reproduce satisfactory examination results. Computed tomography system purchasers are generally concerned with application requirements. Computed tomography system suppliers are generally concerned with the system component selection to meet the purchaser's performance requirements. This guide is not intended to be limiting or restrictive, but rather to address the relationships between application requirements and performance specifications that must be understood and considered for proper CT system selection.
1.2 Computed tomography (CT) may be used for new applications or in place of radiography or radioscopy, provided that the capability to disclose physical features or indications that form the acceptance/rejection criteria is fully documented and available for review. In general, CT has lower spatial resolution than film radiography and is of comparable spatial resolution with digital radiography or radioscopy unless magnification is used. Magnification can be used in CT or radiography/radioscopy to increase spatial resolution but concurrently with loss of field of view.
1.3 Computed tomography (CT) systems use a set of transmission measurements made along a set of paths projected through the object from many different directions. Each of the transmission measurements within these views is digitized and stored in a computer, where they are subsequently conditioned (for example, normalized and corrected) and reconstructed, typically into slices of the object normal to the set of projection paths by one of a variety of techniques. If many slices are reconstructed, a three dimensional representation of the object is obtained. An in-depth treatment of CT principles is given in Guide E1441.
1.4 Computed tomography (CT), as with conventional radiography and radioscopic examinations, is broadly applicable to any material or object through which a beam of penetrating radiation may be passed and detected, including metals, plastics, ceramics, metallic/nonmetallic composite material and assemblies. The principal advantage of CT is that it has the potential to provide densitometric (that is, radiological density and geometry) images of thin cross sections through an object. In many newer systems the cross-sections are now combined into 3D data volumes for additional interpretation. Because of the absence of structural superposition, images may be much easier to interpret than conventional radiological images. The new purchaser can quickly learn to read CT data because images correspond more closely to the way the human mind visualizes 3D structures than conventional projection radiology. Further, because CT images are digital, the images may be enhanced, analyzed, compressed, archived, input as data into performance calculations, compared with digital data from other nondestructive evaluation modalities, or transmitted to other locations for remote viewing. 3D data sets can be rendered by computer graphics i...
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Designation: E1672 − 12
Standard Guide for
1
Computed Tomography (CT) System Selection
This standard is issued under the fixed designation E1672; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* stored in a computer, where they are subsequently conditioned
(for example, normalized and corrected) and reconstructed,
1.1 This guide covers guidelines for translating application
typicallyintoslicesoftheobjectnormaltothesetofprojection
requirements into computed tomography (CT) system
paths by one of a variety of techniques. If many slices are
requirements/specifications and establishes a common termi-
reconstructed, a three dimensional representation of the object
nology to guide both purchaser and supplier in the CT system
is obtained.An in-depth treatment of CT principles is given in
selection process. This guide is applicable to the purchaser of
Guide E1441.
both CT systems and scan services. Computed tomography
systems are complex instruments, consisting of many compo-
1.4 Computed tomography (CT), as with conventional radi-
nents that must correctly interact in order to yield images that
ographyandradioscopicexaminations,isbroadlyapplicableto
repeatedly reproduce satisfactory examination results. Com-
any material or object through which a beam of penetrating
puted tomography system purchasers are generally concerned
radiation may be passed and detected, including metals,
with application requirements. Computed tomography system
plastics, ceramics, metallic/nonmetallic composite material
suppliers are generally concerned with the system component
and assemblies.The principal advantage of CTis that it has the
selection to meet the purchaser’s performance requirements.
potential to provide densitometric (that is, radiological density
This guide is not intended to be limiting or restrictive, but
and geometry) images of thin cross sections through an object.
rather to address the relationships between application require-
In many newer systems the cross-sections are now combined
ments and performance specifications that must be understood
into 3D data volumes for additional interpretation. Because of
and considered for proper CT system selection.
the absence of structural superposition, images may be much
easier to interpret than conventional radiological images. The
1.2 Computed tomography (CT) may be used for new
new purchaser can quickly learn to read CT data because
applications or in place of radiography or radioscopy, provided
images correspond more closely to the way the human mind
that the capability to disclose physical features or indications
visualizes 3D structures than conventional projection radiol-
that form the acceptance/rejection criteria is fully documented
ogy.Further,becauseCTimagesaredigital,theimagesmaybe
and available for review. In general, CT has lower spatial
enhanced, analyzed, compressed, archived, input as data into
resolution than film radiography and is of comparable spatial
performance calculations, compared with digital data from
resolution with digital radiography or radioscopy unless mag-
other nondestructive evaluation modalities, or transmitted to
nification is used. Magnification can be used in CT or
other locations for remote viewing. 3D data sets can be
radiography/radioscopy to increase spatial resolution but con-
rendered by computer graphics into solid models. The solid
currently with loss of field of view.
models can be sliced or segmented to reveal 3D internal
1.3 Computed tomography (CT) systems use a set of trans-
information or output as CAD files. While many of the details
mission measurements made along a set of paths projected
are generic in nature, this guide implicitly assumes the use of
through the object from many different directions. Each of the
penetrating radiation, specifically X rays and gamma rays.
transmission measurements within these views is digitized and
1.5 Units—The values stated in SI units are to be regarded
as standard. The values given in parentheses are mathematical
1
This guide is under the jurisdiction of ASTM Committee E07 on Nondestruc-
conversions to inch-pound units that are provided for informa-
tive Testing and is the direct responsibility of Subcommittee E07.01 on Radiology
tion only and are not considered standard.
(X and Gamma) Method.
Current edition approved June 15, 2012. Published September 2012. Originally
1.6 This standard does not purport to address all of the
approved in 1995. Last previous edition approved in 2006 as E1672
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:E1672–06 Designation: E1672 – 12
Standard Guide for
1
Computed Tomography (CT) System Selection
This standard is issued under the fixed designation E1672; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope Scope*
1.1 This guide covers guidelines for translating application requirements into computed tomography (CT) system requirements/
specificationsandestablishesacommonterminologytoguidebothpurchaserandsupplierintheCTsystemselectionprocess.This
guide is applicable to the purchaser of both CT systems and scan services. Computed tomography systems are complex
instruments, consisting of many components that must correctly interact in order to yield images that repeatedly reproduce
satisfactory examination results. Computed tomography system purchasers are generally concerned with application requirements.
Computed tomography system suppliers are generally concerned with the system component selection to meet the purchaser’s
performance requirements. This guide is not intended to be limiting or restrictive, but rather to address the relationships between
application requirements and performance specifications that must be understood and considered for proper CT system selection.
1.2Computed tomography (CT) may be used for new applications or in place of film radiography, provided that the capability
to disclose physical features or indications that form the acceptance/rejection criteria is fully documented and available for review.
1.3Computed tomography (CT) systems use a set of transmission measurements made along a set of paths projected through the
object from many different directions. Each of the transmission measurements within these views is digitized and stored in a
computer, where they are subsequently conditioned (for example, normalized and corrected) and reconstructed by one of a variety
of techniques. An in-depth treatment of CT principles is given in Guide
1.2 Computed tomography (CT) may be used for new applications or in place of radiography or radioscopy, provided that the
capability to disclose physical features or indications that form the acceptance/rejection criteria is fully documented and available
for review. In general, CT has lower spatial resolution than film radiography and is of comparable spatial resolution with digital
radiography or radioscopy unless magnification is used. Magnification can be used in CT or radiography/radioscopy to increase
spatial resolution but concurrently with loss of field of view.
1.3 Computed tomography (CT) systems use a set of transmission measurements made along a set of paths projected through
the object from many different directions. Each of the transmission measurements within these views is digitized and stored in a
computer,wheretheyaresubsequentlyconditioned(forexample,normalizedandcorrected)andreconstructed,typicallyintoslices
of the object normal to the set of projection paths by one of a variety of techniques. If many slices are reconstructed, a three
dimensional representation of the object is obtained. An in-depth treatment of CT principles is given in Guide E1441.
1.4 Computed tomography (CT), as with conventional radiography and radioscopic examinations, is broadly applicable to any
material or object through which a beam of penetrating radiation may be passed and detected, including metals, plastics, ceramics,
metallic/nonmetallic composite material and assemblies. The principal advantage of CT is that it provides has the potential to
provide densitometric (that is, radiological density and geometry) images of thin cross sections through an object. In many newer
systems the cross-sections are now combined into 3D data volumes for additional interpretation. Because of the absence of
structural superposition, images are may be much easier to interpret than conventional radiological images.The new purchaser can
quickly learn to read CT data because images correspond more closely to the way the human mind visualizes 3-D3D structures
than conventional projection radiology. Further, because CT images are digital, the images may be enhanced, analyzed,
compressed,archived,inputasdataintoperformancecalculations,comparedwithdigitaldatafromothernondestructiveevaluation
modal
...
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