oSIST prEN ISO 10360-11:2021

Geometrical product specifications (GPS) - Acceptance and reverification tests for coordinate measuring systems (CMS) - Part 11: CMSs using the principle of X-ray computed tomography (CT) (ISO/DIS 10360-11:2021)

The intention is to achieve comparability with the characteristics of coordinate measuring devices with tactile and with optical sensors. The characteristics described in this part serve for the specification of coordinate measuring devices with CT sensors and for a comparison between various measurement systems.

Geometrische Produktspezifikation und -prüfung (GPS) - Annahmeprüfung und Bestätigungsprüfung für Koordinatenmessgeräte (KMG) - Teil 11: Computertomografie (ISO/DIS 10360-11:2021)

Der Zweck dieses Dokuments ist es, messtechnische Merkmale und Verfahren für die Prüfung von KMS festzulegen, die als Einzelsensoren nach dem CT-Prinzip (basierend auf dem Röntgenstrahlen-Schwächungs-kontrast) arbeiten und für dimensionelle Messungen an technischen Werkstücken vorgesehen sind. Die medizinische Bildgebung, medizinische dimensionelle Messungen und native, zerstörungsfreie (Material-)Prüfanwendungen der CT (z. B. Fehleranalysen) sind somit ausgeschlossen. Die mit diesem Dokument verbundene Absicht ist — soweit möglich — für Vergleichbarkeit mit den messtechnischen Merkmalen von KMS zu sorgen, die Tastnadeln und/oder optische Sensoren verwenden.
KMS, die mit anderen Sensoren als CT arbeiten, sind von diesem Dokument abgedeckt, sofern diese Sensoren nur für den Aufbau der Messeinrichtung und die Vorbereitung der Messungen, bei denen CT zum Einsatz kommt, verwendet werden.
ANMERKUNG KMS, die in Verbindung mit der CT weitere Sensoren zur Durchführung von Messungen nutzen, können nach ISO 10360-9 spezifiziert und geprüft werden.
Dieses Dokument deckt KMS ab, die CT als Messtechnik einsetzt und die verschiedene Hardware-Konfigurationen (Anhang A) und unterschiedliche Abtastmodi (Anhang B) anwenden. Dieses Dokument legt messtechnische Merkmale und Verfahren zur Prüfung von speziell für nicht gradientenbehaftete, homogene Monomaterialien vorgesehenen höchstzulässigen Abweichungen (en: maximum permissible errors, MPEs) fest, d. h. für Messungen anhand von Bezugsnormalen, die aus nur einem (maßgebenden) Material bestehen, das in Bezug auf die Schwächung von Röntgenstrahlen keinen maßgebenden lateralen oder räumlichen Gradienten aufweist.
Dieses Dokument legt keine messtechnischen Merkmale oder damit verbundenen Prüfverfahren fest, die für die Messung des Einflusses der Oberflächenrauheit auf CT-basierte KMS-Messungen oder umgekehrt (Messung der Rauheit mit CT-basierten KMS) vorgesehen sind.
Für die Messung der Grenzen von lateralen Strukturen unterhalb einer bestimmten Auflösungsgrenze werden in Anhang E zwei vom Hersteller als optionale messtechnische Merkmale bereitgestellte Arten von Auflösungsangaben genannt.
Dieses Dokument legt die folgenden bei der Anwendung von CT notwendigen Aspekte fest:
- Bezugsnormale, die als Alternative zu Parallelendmaßen verwendet werden können (Anhang C);
- Festlegung der messtechnischen Merkmale für verschiedene Betriebsbedingungen;
- Hinweise zum Einfluss von z. B. Umgebungsbedingungen, mathematischen Datenfiltern und der Beschaffenheit der Oberfläche der Maßverkörperung auf die Messung.

Spécification géométrique des produits (GPS) - Essais de réception et de vérification périodique des machines à mesurer tridimensionnelles (MMTs) - Partie 11: MMTs utilisant le principe de la tomographie informatisée (CT) (ISO/DIS 10360-11:2021)

Specifikacija geometrijskih veličin izdelka (GPS) - Preskusi za sprejemljivost in ponovno overjanje koordinatnih merilnih strojev (KMS) - 11. del: KMS, ki uporabljajo princip rentgenske računalniške tomografije (CT) (ISO/DIS 10360-11:2021)

General Information

• Status: Not Published
• Public Enquiry End Date: 21-Jun-2021
• ICS: 17.040.30 - Measuring instruments
• ICS: 17.040.40 - Geometrical Product Specification (GPS)
• Technical Committee: ISEL - Mechanical elements
• Current Stage: 98 - Abandoned project (Adopted Project)
• Start Date: 14-Jun-2024
• Due Date: 19-Jun-2024
• Completion Date: 14-Jun-2024
• Ref Project: prEN ISO 10360-11 - Geometrical Product Specifications (GPS) - Acceptance and reverification tests for coordinate measuring machines (CMM) - Part 11: Computed tomography

Overview

The oSIST prEN ISO 10360-11:2021 standard, titled "Geometrical Product Specifications (GPS) - Acceptance and reverification tests for coordinate measuring machines (CMM) - Part 11: Computed tomography (CT)", is published by CEN. It defines the acceptance criteria and reverification tests for coordinate measuring systems (CMS) that utilize X-ray computed tomography (CT) as their fundamental measurement principle. This standard aims to align the performance characteristics of CT-based CMS with those of coordinate measuring devices using tactile probes and optical sensors, ensuring comparability across different measurement technologies.

Primarily, this document focuses on CMS dedicated to dimensional measurements of technical workpieces through X-ray attenuation-based CT imaging. It excludes medical imaging and non-destructive material testing purposes, addressing only homogenous mono-materials without significant lateral or spatial gradients in X-ray attenuation.

Key Topics

• Metrological Characteristics for CT-Based CMS
  The standard specifies quantitative metrics to evaluate CT-based coordinate measuring systems, including maximum permissible errors (MPEs) for dimensional measurements.

• Testing Methodology
  Acceptance and reverification tests assess the accuracy and repeatability of CT-based CMS. These tests include volumetric length measurement errors and probing errors to verify system compliance with GPS standards.

• Material and Environmental Considerations
  Guidance is provided on the choice of reference materials, their homogeneity, thermal expansion properties, and the influence of environmental and operating conditions on measurement accuracy.

• Hardware Configurations and Scanning Modes
  Annexes describe various hardware configurations of CT-based CMS and different scanning modes, offering testing guidance tailored to system design and application requirements.

• Resolution and Measurement Uncertainty
  The standard addresses resolution limits for lateral structures and methods to evaluate test value uncertainty. It also includes criteria for surface roughness and form errors affecting measurement reliability.

• Documentation and Reporting
  Templates and guidelines for reporting acceptance and reverification test results ensure standardized communication of measurement system performance.

Applications

• Industrial Dimensional Measurement
  CT-based CMS are increasingly used for precise, non-contact measurement of internal and external geometries in manufacturing processes.

• Quality Control and Assurance
  Ensuring compliance with ISO 10360-11 helps manufacturers verify that CT measurement systems provide reliable, repeatable results critical for product quality.

• Comparative Metrology
  The standard offers a basis for benchmarking CT measurement systems against traditional tactile and optical CMMs, facilitating informed equipment selection and integration.

• Calibration and Maintenance
  Regular acceptance testing and reverification per this standard help maintain CT CMS accuracy over time, accounting for equipment aging or environmental changes.

Related Standards

• ISO 10360-2 and ISO 10360-5
  Standards addressing acceptance and reverification tests for tactile probing coordinate measuring systems.

• ISO 10360-8
  Focuses on CMS that use optical distance sensors, forming a basis for comparable testing approaches.

• ISO 10360-9
  Governs CMS that combine CT with other sensor technologies for measurement purposes.

• ISO/TR 14638
  Provides background on the Geometrical Product Specification system and GPS matrix models related to coordinate measurement technologies.

Conclusion

oSIST prEN ISO 10360-11:2021 establishes essential geometrical product specifications (GPS) criteria ensuring that coordinate measuring systems based on X-ray computed tomography (CT) meet stringent performance requirements. By standardizing acceptance and reverification testing methods, the document facilitates consistency, accuracy, and comparability across diverse CMS technologies-supporting critical dimensional measurement applications in high-precision manufacturing and quality control environments. Adherence to this standard empowers organizations to maintain measurement traceability and reliability using advanced CT-based coordinate metrology.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2021
Specifikacija geometrijskih veličin izdelka (GPS) - Preskusi za sprejemljivost in
ponovno overjanje koordinatnih merilnih strojev (KMS) - 11. del: KMS, ki
uporabljajo princip rentgenske računalniške tomografije (CT) (ISO/DIS 10360-
11:2021)
Geometrical product specifications (GPS) - Acceptance and reverification tests for
coordinate measuring systems (CMS) - Part 11: CMSs using the principle of X-ray
computed tomography (CT) (ISO/DIS 10360-11:2021)
Geometrische Produktspezifikation und -prüfung (GPS) - Annahmeprüfung und
Bestätigungsprüfung für Koordinatenmessgeräte (KMG) - Teil 11: Computertomografie
(ISO/DIS 10360-11:2021)
Spécification géométrique des produits (GPS) - Essais de réception et de vérification
périodique des machines à mesurer tridimensionnelles (MMTs) - Partie 11: MMTs
utilisant le principe de la tomographie informatisée (CT) (ISO/DIS 10360-11:2021)
Ta slovenski standard je istoveten z: prEN ISO 10360-11
ICS:
17.040.30 Merila Measuring instruments
17.040.40 Specifikacija geometrijskih Geometrical Product
veličin izdelka (GPS) Specification (GPS)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT INTERNATIONAL STANDARD
ISO/DIS 10360-11
ISO/TC 213 Secretariat: BSI
Voting begins on: Voting terminates on:
2021-03-30 2021-06-22
Geometrical product specifications (GPS) — Acceptance
and reverification tests for coordinate measuring
systems (CMS) —
Part 11:
CMSs using the principle of X-ray computed tomography
(CT)
Spécification géométrique des produits (GPS) — Essais de réception et de vérification périodique des
machines à mesurer tridimensionnelles (MMTs) —
Partie 11: MMTs utilisant le principe de la tomographie informatisée (CT)
ICS: 17.040.30; 17.040.40
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 10360-11:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2021

ISO/DIS 10360-11:2021(E)
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
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Published in Switzerland
ii © ISO 2021 – All rights reserved

ISO/DIS 10360-11:2021(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 4
5 Requirements for metrological characteristics . 7
5.1 Specification requirements . 7
5.2 Environmental conditions . 9
5.3 Operating conditions . 9
5.4 Workpiece loading effects .10
5.5 Measurement time .10
5.6 Criteria for material choice and material properties of reference standards and
obstructive bodies .11
5.6.1 Material class concept .11
5.6.2 Requirements for material classes .12
5.6.3 Homogeneity of materials and consequences for testing.13
5.6.4 Thermal expansion of reference standards .14
5.7 Criteria for roughness and form errors of reference standards .15
5.8 Metrological characteristics assessed with explicit use of pre-knowledge .16
6 Acceptance and reverification tests .18
6.1 General testing principles .18
6.1.1 Overview .18
6.1.2 Common testing criteria .21
6.2 Probing errors .23
6.2.1 Principle .23
6.2.2 Measuring equipment .24
6.2.3 Procedure .25
6.2.4 Derivation of test results .26
6.3 Volumetric length measurement error .26
6.3.1 Principle .26
6.3.2 Measuring equipment .27
6.3.3 Procedure .28
6.3.4 Derivation of test results .30
7 C onformity with the specifications .31
7.1 Acceptance tests .31
7.2 Reverification tests .31
7.3 Interim checks .31
7.3.1 Reference standards .32
7.3.2 Procedure .32
7.3.3 Analysis and conformity with specifications .32
8 Application .32
8.1 Acceptance test .32
8.2 Reverification test .32
8.3 Interim check .32
9 Indication in product documentation and data sheets .32
Annex A (informative) Hardware configurations of CT-based CMSs .34
Annex B (informative) Description of CT scanning modes and guidance for testing .35
Annex C (informative) Reference standards for length error measurements .39
ISO/DIS 10360-11:2021(E)
Annex D (informative) Optional metrological characteristics .43
Annex E (informative) Resolution statements for dimensional measurements .53
Annex F (normative) Procedure and mathematical adjustments for metrological
characteristics assessed with non-normal CTE material reference standards .55
Annex G (normative) Guideline for evaluation of the test value uncertainty .58
Annex H (informative) Template for acceptance test or reverification test reporting .65
Annex I (informative) Relation to the GPS matrix model .69
Bibliography .70
iv © ISO 2021 – All rights reserved

ISO/DIS 10360-11:2021(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see https:// www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product
specifications and verification.
A list of all parts in the ISO 10360 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
ISO/DIS 10360-11:2021(E)
Introduction
This document is a geometrical product specification (GPS) standard and is to be regarded as a general
GPS standard (see ISO/TR 14638). It influences link 5 of the chains of standards on size, distance,
radius, angle, form, orientation, location, run-out and datums.
For more detailed information of the relation of this document to other standards and the GPS matrix
model see Annex I.
In close reliance on ISO 10360-2 and ISO 10360-5 for coordinate measuring systems (CMSs) equipped
with contact probing systems as well as ISO 10360-8 for CMSs with optical distance sensors, this
document specifies the acceptance and reverification tests for verifying the performance of CMSs
that use the principle of X-ray computed tomography (CT). Where technically possible, the testing
methodology of these parts of ISO 10360 is intended to be similar.
The metrological characteristics described in this document serve both for the specification of CMSs
that use the principle of CT and for comparison between various coordinate measurement systems.
This document is intentionally dedicated to CMSs that use CT where measurements are predominantly
based on the attenuation contrast visible when penetrating physical matter. This document may also be
applied to CMSs which use other tomographic measurement principles based on a mutual agreement.
vi © ISO 2021 – All rights reserved

DRAFT INTERNATIONAL STANDARD ISO/DIS 10360-11:2021(E)
Geometrical product specifications (GPS) — Acceptance
and reverification tests for coordinate measuring
systems (CMS) —
Part 11:
CMSs using the principle of X-ray computed tomography
(CT)
1 Scope
The purpose of this document is to define metrological characteristics and methods for testing CMSs
that use the principle of CT (based on X-ray attenuation contrast) as a single sensor and which are
dedicated to dimensional measurements of technical workpieces. This excludes medical imaging,
medical dimensional measurements and native non-destructive (material) testing applications of CT
(e.g. defect analyses). The intention of this document is to achieve – where possible – comparability
with the metrological characteristics of CMSs employing tactile probes and/or optical sensors.
CMSs which use sensors other than CT are covered by this document if such sensors are used for setting
up and preparing measurements for which CT is used, only.
NOTE CMSs which use other sensors together with CT to perform measurements can be specified and tested
using ISO 10360-9.
This document covers CMSs which use CT as a measurement technology and which employ various
hardware configurations (Annex A) and different scanning modes (Annex B). This document defines
metrological characteristics and methods for testing maximum permissible errors (MPEs) that are
intended specifically for non-gradient, homogeneous mono-materials, i.e. measurements of reference
standards that consist of only one (relevant) material that has no relevant lateral or spatial gradient in
the attenuation of X-rays.
This document does not define metrological characteristics or related testing methods that are
dedicated to measuring the influence of surface roughness on CT-based CMS measurements or vice-
versa (measuring roughness with CT-based CMSs).
For measuring limits of lateral structures below a certain resolution limit, Annex E mentions two types
of resolution statements which the manufacturer provided as optional metrological characteristics.
This document establishes the following aspects necessary when using CT:
— Reference standards usable as alternatives to gauge blocks (Annex C)
— Definition of metrological characteristics for various operating conditions
— Notes on the impact on the measurement of, for example, environmental conditions, mathematical
data filters and the nature of the measurement standard’s surface
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes the requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/DIS 10360-11:2021(E)
ISO 1, Geometrical product specifications (GPS) — Standard reference temperature for the specification of
geometrical and dimensional properties
ISO 3650, Geometrical Product Specifications (GPS) — Length standards — Gauge blocks
ISO 10360-1, Geometrical Product Specifications (GPS) — Acceptance and reverification tests for coordinate
measuring machines (CMM) — Part 1: Vocabulary
ISO 10360-2, Geometrical product specifications (GPS) — Acceptance and reverification tests for coordinate
measuring machines (CMM) — Part 2: CMMs used for measuring linear dimensions
ISO 10360-5, Geometrical product specifications (GPS) — Acceptance and reverification tests for coordinate
measuring systems (CMS) — Part 5: Coordinate measuring machines (CMMs) using single and multiple
stylus contacting probing systems using discrete point and/or scanning measuring mode
ISO 10360-8, Geometrical product specifications (GPS) — Acceptance and reverification tests for coordinate
measuring systems (CMS) — Part 8: CMMs with optical distance sensors
ISO 10360-9, Geometrical product specifications (GPS) — Acceptance and reverification tests for coordinate
measuring systems (CMS) — Part 9: CMMs with multiple probing systems
ISO 14253-1, Geometrical product specifications (GPS) — Inspection by measurement of workpieces and
measuring equipment — Part 1: Decision rules for verifying conformity or nonconformity with specifications
ISO 14253-5, Geometrical product specifications (GPS) — Inspection by measurement of workpieces and
measuring equipment — Part 5: Uncertainty in verification testing of indicating measuring instruments
ISO/TS 17865, Geometrical product specifications (GPS) — Guidelines for the evaluation of coordinate
measuring machine (CMM) test uncertainty for CMMs using single and multiple stylus contacting
probing systems
ISO/TS 23165, Geometrical product specifications (GPS) — Guidelines for the evaluation of coordinate
measuring machine (CMM) test uncertainty
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
ISO/TR XXXXX, Resolution statements for dimensional measurements of CMSs using the principle of X-ray
computed tomography (CT) (see Annex E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in VIM and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
This document describes physical material measures used for the measurement of the metrological
characteristics. In this document, the physical material measures are denoted as “reference
measurement standards” or “reference standards” for short (see VIM). This document uses – in
contrast to other standards and guidelines – the expression “artefact” only for imaging errors of the
CMSs, as this meaning and expression is common in the field of CT. For probing error assessment, a
calibrated sphere is used; this reference standard will be denoted as the “test sphere”. For assessing
length measurement errors, various types, different reference standards may be used (Annex C). When
referring to a single length assessed with a standard, the expression “test length” is used. For the
readability of this document, the term “Gaussian” refers to an unweighted least-squares fit without any
constraint (position or diameter, if applicable).
2 © ISO 2021 – All rights reserved

ISO/DIS 10360-11:2021(E)
3.1
material class
j
Designation of material class j. The metrological characteristic associated with material class j shall be
measured with a reference standard and an obstructive body – if applicable – both made from a material
within the respective material class definition, j (j = Pl for class “plastic”, j = Al for class “aluminium”, j =
Fe for class “steel”; see 5.6)
Note 1 to entry: An obstructive body is an uncalibrated, separate piece of material placed next to a reference
standard to adjust the penetration length (see Table 2) of the material seen by X-rays in individual projections of
a CT scan. 5.6 describes criteria for the material of the obstructive body and, if required, the mounting material
(5.6.3).
Note 2 to entry: Occasionally, the acquisition of a complete set of X-ray projections of a single CT measurement is
called a CT scan.
Note 3 to entry: j = Fe is deduced from chemical symbol Fe for iron, the major component of steel.
3.2
probing form dispersion error
P
Form.Sph.D95%.j::CT
smallest possible width of a spherical shell which contains 95 % of all data points measured on a test
sphere of material class j (3.1)
Note 1 to entry: The “D” inside ‘D95%’ indicated that the characteristic feature of this metrological characteristic
is the “dispersion” of the population, while the “95%” inside ‘D95%’ refers to the coverage of 95 % of all points.
3.3
probing form error All
P
Form.Sph.All.j::CT
smallest possible width of a spherical shell which contains all data points measured on a test sphere of
material class j (3.1)
3.4
probing size error All
P
Size.Sph.All.j::CT
error of indication of the (signed) difference between the diameter of a least-squares fit of all points
measured on a test sphere of material class j (3.1)and its calibrated diameter
3.5
volumetric length measurement error
E
Vol.j::CT
error of indication when measuring a calibrated test length where the error is deduced from the
distance between two points each determined from multiple measurement points of two respective
geometrical elements on a reference standard of material class j (3.1)
Note 1 to entry: The absolute value of the volumetric length measurement error is in nearly all cases smaller than
the bidirectional length measurement error.
3.6
maximum permissible probing form dispersion error
P
Form.Sph.D95%.j::CT,MPE
MPE of P
Form.Sph.D95%.j::CT
3.7
maximum permissible probing form error All
P
Form.Sph.All.j::CT,MPE
MPE of P
Form.Sph.All.j::CT
ISO/DIS 10360-11:2021(E)
3.8
maximum permissible probing size error All
P
Size.Sph.All.j::CT,MPE
MPE of P
Size.Sph.All.j::CT
3.9
maximum permissible volumetric length measurement error
E
Vol.j::CT,MPE
MPE of E
Vol.j::CT
3.10
pre-knowledge
prior knowledge according to 5.8 of the reference standard and/or the obstructive body being measured
in acceptance testing that is not directly acquired by the CMS under test but could affect the points
measured of the reference standard
Note 1 to entry: Examples of pre-knowledge include nominal chemical composition and CAD-related information
such as nominal geometry, nominal surface normal vectors, material information and nominal dimensions.
Note 2 to entry: Metrological characteristics and respective MPE values which are assessed or specified with the
use of pre-knowledge receive a test qualifier, ‘PreK’ or ‘CAD’, after the first colon.
Note 3 to entry: In case that there are other test qualifiers to be inserted, the test qualifiers ‘PreK’ or ‘CAD’ shall
be the first after the colon.
Note 4 to entry: The ‘CAD’ test qualifier indicates pre-knowledge restricted to only CAD-related information –
without any specific material designation or chemical composition knowledge. The qualifier PreK allows CAD-
related information and more, making CAD-related information a subset of PreK information.
Note 5 to entry: Examples of metrological characteristics where the explicit use of pre-knowledge is indicated by
a ‘PreK’ test qualifier are P and E , with respective MPE values P
Form.Sph.D95%.j:PreK:CT Bi.j:PreK:CT Form.Sph.D95%.j:PreK:
and E . The use of a ‘CAD’ qualifier is similar.
C T , M P E Bi.j:PreK: CT ,MPE
Note 6 to entry: The auxiliary quantity E may contain also a ‘PreK’ (or similarly ‘CAD’) test qualifier.
Bi.shrt.j:PreK:CT
However, there is no attributed MPE value for this quantity.
4 Symbols and abbreviated terms
For the purposes of the main part of this document, the symbols in Table 1 and Table 2 apply.
NOTE Table D.1 contains symbols of optional metrological characteristics and auxiliary quantities used in
the Annexes of this document.
Table 1 — Symbols of mandatory metrological characteristics
References in
Symbol Name
this document
P probing form dispersion error 3.2, 3.6, 5.1, 6.2,
Form.Sph.D95%.j::CT
7.1, 7.2, 7.3.3, 9,
Annex D.3.4.4.3,
Annex H
P probing form error All 3.3, 3.7, 5.1,
Form.Sph.All.j::CT
6.2.1, 6.2.3.1,
6.2.3.3, 7.1, 7.2,
7.3.3, Annex
D.3.3.3, Annex H
P probing size error All 3.4, 3.8, 5.1, 6.2,
Size.Sph.All.j::CT
7.1, 7.2, 7.3.3,
Annex D.3.4.4.3,
Annex H
4 © ISO 2021 – All rights reserved

ISO/DIS 10360-11:2021(E)
Table 1 (continued)
References in
Symbol Name
this document
E volumetric length measurement error 3.5, 3.9, 5.1,
Vol.j::CT
6.3, 7.1, 7.2,
7.3.3, Annex
C, Annex D.1,
Annex D.3.4.1,
Annex D.3.4.4.2,
Annex F.1,
Annex F.2
P maximum permissible probing form dispersion error 3.6, 5.1, 6.2.4, 7.1,
Form.Sph.D95%.j::CT,MPE
7.2, 7.3.3, 9
P maximum permissible probing form error All 3.7, 5.1, 6.2.4, 7.1,
Form.Sph.All.j::CT,MPE
7.2, 7.3.3
P maximum permissible probing size error All 3.8, 5.1, 6.2.4, 7.1,
Size.Sph.All.j::CT,MPE
7.2, 7.3.3
E maximum permissible volumetric length measurement error 3.9, 6.3.4, 7.1, 7.2,
Vol.j::CT,MPE
7.3.3, Annex F.1
Table 2 — Symbols of auxiliary quantities
References in
Symbol Name (with annotation) & note(s)
this document
V measurement volume 5.1, 6.1.2
Note 1 to entry: The measurement volume is often a cylinder, but not
always. Often CMSs feature a cylindrical measurement volume where
height and diameter of the cylinder are equal, but there exist also
CMSs which use X-ray detectors with different height and width. For
these CMSs the height and diameter of the cylindrical measurement
volume is different.
V minimum measurement volume (specified with MPEs) 5.1, 6.1.2, Annex H
Note 1 to entry: Measurement volume V corresponds to geometrical
magnification M .
V maximum measurement volume (specified with MPEs) 5.1, 6.1.2, Annex H
Note 1 to entry: Measurement volume V corresponds to geometrical
magnification M
2.
ISO/DIS 10360-11:2021(E)
Table 2 (continued)
References in
Symbol Name (with annotation) & note(s)
this document
L Maximum penetration length through the reference standard, ob- 5.1, 5.6.3, 6.1.2,
p
structive body (if applicable) and any auxiliary material (if present) Annex D.3.4.4.2
when collecting projection images of a single CT scan.
Note 1 to entry: The "penetration length" is the individual path length
of any X-ray through any matter (in a way similar to that described
for L ), i.e. through the reference standard, obstructive body (if
p
applicable) and any auxiliary material (base mount, temperature
sensors, cables, etc. ; if present), when collecting projection images
of a single CT scan. The penetration length is counted (i.e. summed)
for rays having a line trajectory from the X-ray source to a specific
detector pixel. The penetration length is different for any pixel of the
detector and also varies with rotation angle for each projection of a
single CT scan. All penetration lengths are smaller than or equal to
L . The minimum penetration length is usually nearly zero (for rays
p
passing through air only; such rays are always present for standard
CT scanning).
Note 2 to entry: If different materials allowed for testing are pen-
etrated (i.e. materials of material class j and respective substitute
materials of material class j), the lengths penetrated in each material
are added to obtain L .
p
Note 3 to entry: If “other materials” (i.e. auxiliary materials) than
those mentioned in the previous note are penetrated, for each mate-
rial length penetrated through this material a comparable length of a
material from material class j must be attributed. A comparable length
from a material from material class j creates the same absorption as
the “other material” being penetrated. Lengths according to Note 2
to entry: and according to Note 3 to entry: are added to obtain L
p
Note 4 to entry: It is against the intention of the acceptance test to
let the lengths according to Note 3 to entry: make a significant con-
tribution to L .
p
L (j) Manufacturer-specified maximum for L (as a rated operating con- 5.1, 6.1.2,
p,max p
dition) for measuring reference standards made from material class 6.2.2.1, 6.3.3.1,
j; material identification is given in brackets. Annex D.3.4.3,
Annex D.3.4.4.2,
The statement of L (j) shall be made together with respective X-ray
p,max
Annex D.3.4.4.3,
parameters (e.g. X-ray tube voltage, X-ray tube power, prefilter mate-
Annex H
rial and thickness and exposure time) and measurement parameters.
Note 1 to entry: L (j) is an attribute to all metrological charac-
p,max
teristics, i.e. length measurement errors, probing errors, resolution
statements.
Note 2 to entry: L (j) depends on the selected measurement
p,max
parameters.
Note 3 to entry: Providing L (j) together with respective X-ray
p,max
parameters and respective measurement parameters should enable
the user to measure a workpiece with a maximum penetration length
of L (j) from a given material.
p,max
Note 4 to entry: L (j) can have different values for different
p,max
measurement volumes.
τ Single CT scan projection measurement time (time to assess all pro- 5.5
jections for acceptance testing of a single CT scan)
τ Minimum value of τ (as specified by the manufacturer) 5.5, Annex H
min
τ Maximum value of τ (as specified by the manufacturer) 5.5, Annex H
max
6 © ISO 2021 – All rights reserved

ISO/DIS 10360-11:2021(E)
Symbols for metrological characteristics assessed with explicit pre-knowledge
Metrological Characteristics of types as explained above, which have been assessed with explicit pre-
knowledge (see 5.8) receive the test qualifier ‘PreK’ or ‘CAD’ after the first colon.
NOTE The same test qualifier ‘PreK’ or ‘CAD’ can also be used for optional metrological characteristics
described in Annex D.
Abbreviated terms
CAD computer-aided design
CMS coordinate measuring systems (plural CMSs)
CT X-ray computed tomography
CTE linear coefficient of thermal expansion
GPS geometrical product specification(s)
MPE maximum permissible error (plural MPEs), see VIM
VIM International Vocabulary of Metrology (see 2)
5 Requirements for metrological characteristics
5.1 Specification requirements
It is the manufacturer’s responsibility to provide a detailed specification of the MPE values of the
metrological characteristics over all rated conditions, for all specified hardware configurations
(Annex A) and for all specified scanning modes (Annex B). The full specification also covers the
requirements mentioned in 5.2 – 5.8. The manufacturer specifies the MPEs of the metrological
characteristics in such a way that they are maintained throughout the entire measurement volume and
under all rated measurement and operating conditions. To this end, the manufacturer shall describe
the shape of the measurement volume, (e.g. diameter and height). The specification of the measurement
volumes shall fully describe the unique configuration of the system geometry (e.g. the object and
detector positions relative to the source). When declaring MPEs, the manufacturer shall also state
relevant conditions, e.g., the maximum penetration length L .
p,max
This document considers two types of metrological characteristics: (1) those assessed without pre-
knowledge and (2) those assessed with pre-knowledge (indicated by the ‘PreK’ or ‘CAD’ test qualifier).
The differences between the cases are covered in 5.8. The actual measurement process is the same in
both cases; hence, for the sake of brevity, only the case without pre-knowledge is described in 6, 7, 8 and
all Annexes.
This document requires that the performance of a CT-based CMS be specified using all, not a subset,
of the mandatory metrological characteristics (see 6.1). Thus, a set of all mandatory metrological
characteristics can be specified either with pre-knowledge (indicated by the ‘PreK’ test qualifier for all
of them or the ‘CAD’ test qualifier for all of them) or without pre-knowledge. It is also possible to specify
more than one complete sets of mandatory specifications covering both cases (with and without pre-
knowledge). The mandatory specifications can be supplemented with optional specifications (see
Table D.1 and Annex D).
The values of the MPEs for any metrological characteristics may be stated by the manufacturer as a
function of the measured length L – if applicable – and of the total penetrated length through matter
L . In all cases, the specification shall be complied with across the CMS’s entire measurement range
p
and under all rated measurement and operating conditions. If the specification is provided by means
ISO/DIS 10360-11:2021(E)
of a formula, the formula shall provide a valid specification value for all specified measurement and
operating conditions.
NOTE 1 The manufacturer is not required to provide the above formula in a specific format. Examples of
possible formulas include (but are not limited to) a linear statement A + B ∙ L + C ∙ L , with constants A, B, C, or
p
alternatively one with only a constant value A.
If technically required, the manufacturer can specify the MPEs as a function of further parameters, e.g.,
• Source to detector distance (for a system with this degree of freedom)
• Measurement volume
• temperature
The maximum penetration length L (j) can be specified as a constant for each material class j. It can
p,max
also be expressed as a function of other parameters, e.g., the measurement volume.
NOTE 2 A further consequence of the change of L (j) with the size of the measurement volume could be a
p,max
change of the measurement parameters (e.g. X-ray tube voltage, prefiltering and X-ray tube current) depending
on the size of the measurement volume.
The specification shall include all system settings and measurement parameters to allow testing
of the performance of a CT-based CMS. Further information on the system under test such as the
software version(s) should also be included. This specification shall be made for measurements of
reference standards measured with air as a surrounding medium. If the specification is made for other
surrounding media, this shall be clearly stated by the manufacturer. When the specification is at a
single point or over a range for a given parameter, the MPE only applies at the specified point or range.
Metrological characteristics beyond those mandated in this document can be specified by mutual
agreement. For metrological characteristics that can have positive or negative values, the MPE value
shall limit the absolute value of the respective metrological characteristic.
The manufacturer may restrict the validity of specified MPEs, e.g., for the following properties:
— The reference standard’s material class
— The maximum penetration length for a specific material class L (j)
p,max
— The measurement volume V (e.g. diameter, height) and the associated magnification M
NOTE 3 Depending on the scanning mode (Annex B) the shape of the measurement volume can differ
from the standard case of a cylinder.
— Environmental conditions (temperature, temperature gradients, etc.)
— Other adjustable parameters that are accessible to the user during normal measurement, e.g., the
use of artefact correction methods (error correction techniques, i.e. data filtering applied to any
step of the CT data processing to overcome specific imaging or measurement errors), mathematical
and physical filters, additional sensors to aid in artefact (see 3) correction (i.e. a further physical
sensor designed to enable the use of a specific artefact correction technique to enhance the quality
of the CT measurement), X-ray voltage, measurement time, point density, etc.
If technically feasible and applicable, the manufacturer shall specify measurement volumes V and
V , where V corresponds to the full volume, i.e. the maximum measurement volume over which the
2 2
CMS can be tested and V sets a lower limit for the measurement volume to be used in testing. The
manufacturer shall specify at least one metrological characteristic set (P , P
Form.Sph.All.j::CT,MPE Form.Sph.
, P and E ). If only one metrological characteristic set is provided,
D95%.j::CT,MPE Size.Sph.All.j::CT,MPE Vol.j::CT
these MPEs shall be valid throughout the range between measurement volumes V and V . If more
1 2
than one metrological characteristic set is stated and the CMS is qualified for measurements which
use measurement volumes between V and V , the manufacturer shall provide a statement describing
1 2
which metrological characteristic set is valid for any measurement volumes between V and V .
1 2
8 © ISO 2021 – All rights reserved

ISO/DIS 10360-11:2021(E)
Depending on the CMS design, the kinematic system and the mode of operation, measurement volumes
of identical size may have different metrological properties (i.e. different MPE values). The manufacturer
shall clearly describe these conditions.
It is recommended that the two specified minimum and maximum measurement volumes V and V
1 2
cover as much of the range of magnifications as possible to avoid restricted metrological characteristics
and disparities between the specified and intended use of a CMS.
Optionally, the manufacturer may provide a statement for the maximum and minimum possible
measurement volume V and V , respectively; here, neither limit is designed for specified
max min
measurements as a CMS. If stated, V and V are provided for information only.
max min
NOTE 3 By definition V ≤ V < V ≤ V
min 1 2 max
NOTE 4 Specifications according to this document (i.e. MPE values) exist only for the interval of measurement
volumes [V , V ] attributed to specifications.
1 2
NOTE 5 P , P , P , E , E and E can have positive
Size.Sph.1x25.j::CT Size.Sph.All.j::CT Size.Sph.D95%.j::CT Vol.j::CT Bi.j::CT Bi.shrt.j::CT
or negative values, whereas P and P ,P are always positive by
Form.Sph.1x25.j::CT Form.Sph.D95%.j::CT Form.Sph.All.j::CT
definition.
5.2 Environmental conditions
Limits for environmental conditions at the installation site shall be specified by:
• the manufacturer, for acceptance tests;
• the user, for interim checks or reverification tests.
The user is responsible for providing the correct environment for housing the CMS throughout testing.
If the environment does not meet the requirement set for the specified metrological characteristics,
MPEs cannot be verified.
5.3 Operating conditions
When conducting the tests in this document, the CMS shall be operated using the procedures
and software (including the correct version) in the manufacturer’s operating manual(s) and the
manufacturer’s specifications that correspond to the metrological characteristics. The rated operating
conditions (i.e., the operating condition for which the MPE is claimed to be valid) shall be specified by
the manufacturer in the relevant operating manual(s) in combination with the respective data sheet(s).
Specific areas in the manufacturer’s manuals to be adhered to may include:
a) limits for environmental conditions (5.2)
b) use of th
...