IEC 60731:2011

IEC 60731 ®
Edition 3.0 2011-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Medical electrical equipment – Dosimeters with ionization chambers as used in
radiotherapy
Appareils électromédicaux – Dosimètres à chambres d’ionisation
utilisés en radiothérapie
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IEC 60731 ®
Edition 3.0 2011-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Medical electrical equipment – Dosimeters with ionization chambers as used in
radiotherapy
Appareils électromédicaux – Dosimètres à chambres d’ionisation
utilisés en radiothérapie
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XD
ICS 11.040.50 ISBN 978-2-88912-382-7

– 2 – 60731 © IEC:2011
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope and object . 9
1.1 Scope . 9
1.2 Object . 9
2 Normative references . 9
3 Terms and definitions . 10
4 General requirements . 22
4.1 BASIC SAFETY and ESSENTIAL PERFORMANCE . 22
4.2 Performance requirements . 22
4.3 REFERENCE VALUES and STANDARD TEST VALUES . 22
4.4 General test conditions and methods . 23
4.4.1 STANDARD TEST CONDITIONS . 23
4.4.2 Test of components . 23
4.4.3 RATED or EFFECTIVE RANGE of dose (or KERMA) rates . 23
4.4.4 UNCERTAINTY OF MEASUREMENT . 24
4.4.5 Adjustments during test . 24
4.4.6 Test conditions particular to CHAMBER ASSEMBLIES. 24
4.4.7 Test conditions particular to MEASURING ASSEMBLIES. 24
4.4.8 Test conditions particular to STABILITY CHECK DEVICES . 25
4.4.9 Use of STABILITY CHECK DEVICES . 25
4.5 Summary tables . 25
4.6 Classification of equipment according to LIMITS OF VARIATION . 32
4.6.1 FIELD-CLASS DOSIMETER . 32
4.6.2 REFERENCE-CLASS DOSIMETER . 32
4.6.3 SCANNING-CLASS DOSIMETER . 32
5 CHAMBER ASSEMBLY performance requirements . 33
5.1 General . 33
5.2 General performance requirements for (RADIOTHERAPY) IONIZATION CHAMBERS . 33
5.2.1 CHAMBER ASSEMBLY LEAKAGE CURRENT without IRRADIATION . 33
5.2.2 Stability . 33
5.2.3 STABILIZATION TIME . 34
5.2.4 Post-irradiation leakage . 34
5.2.5 RATED or EFFECTIVE RANGE of dose rate (continuous radiation) . 35
5.2.6 Maximum RATED dose per pulse (pulsed radiation) . 36
5.2.7 RATED RANGE of field sizes . 37
5.2.8 STRAY RADIATION . 38
5.2.9 Guard/collector insulation . 38
5.2.10 Cable microphony . 39
5.2.11 Polarity of polarizing voltage effect . 39
5.2.12 ELECTROMAGNETIC COMPATIBILITY . 40
5.3 Performance requirements particular to SHELL CHAMBERS . 40
5.3.1 Dependence on RADIATION QUALITY . 40
5.3.2 RATED RANGE of field sizes . 43
5.3.3 Chamber orientation . 44
5.4 Performance requirements particular to PARALLEL-PLATE CHAMBERS . 45

60731 © IEC:2011 – 3 –
5.4.1 Dependence on RADIATION QUALITY . 46
5.4.2 Chamber orientation . 47
5.5 Performance requirements particular to VENTED CHAMBERS . 47
5.5.1 Atmospheric pressure change . 48
5.5.2 Temperature . 48
5.5.3 Humidity . 48
5.6 Performance requirements particular to SEALED CHAMBERS. 49
5.6.1 Atmospheric pressure change . 49
5.6.2 Temperature . 49
6 MEASURING ASSEMBLY performance requirements . 50
6.1 General . 50
6.2 General performance requirements for RADIOTHERAPY DOSIMETERS . 50
6.2.1 EFFECTIVE RANGES . 50
6.2.2 RESOLUTION of the display or data output terminal . 51
6.2.3 Repeatability . 51
6.2.4 Long-term stability . 51
6.2.5 STABILIZATION TIME . 52
6.2.6 ELECTROMAGNETIC COMPATIBILITY . 52
6.3 Performance requirements particular to dosimeters . 53
6.3.1 ZERO DRIFT . 53
6.3.2 ZERO SHIFT . 54
6.3.3 NON-LINEARITY . 55
6.3.4 Range changing . 56
6.3.5 Dead time . 57
6.3.6 Temperature . 57
6.3.7 Humidity . 57
6.3.8 STRAY RADIATION effect . 58
6.3.9 Charge leakage . 58
6.3.10 Dose rate dependence of dosimeters . 59
6.4 Performance requirements particular to dose rate meters . 60
6.4.1 ZERO DRIFT . 60
6.4.2 ZERO SHIFT . 61
6.4.3 NON-LINEARITY . 61
6.4.4 Range changing . 62
6.4.5 RESPONSE TIME . 64
6.4.6 Temperature . 65
6.4.7 Humidity . 65
6.4.8 STRAY RADIATION effect . 66
6.5 Performance requirements particular to battery-operated MEASURING
ASSEMBLIES . 66
6.6 Performance requirements particular to supply mains-operated MEASURING
ASSEMBLIES . 67
6.6.1 MAINS VOLTAGE – static . 67
6.6.2 MAINS VOLTAGE – VARIATION during a measurement . 67
7 STABILITY CHECK DEVICE performance requirements . 68
7.1 General . 68
7.2 General performance requirements for STABILITY CHECK DEVICES . 68
7.2.1 Long-term stability . 68
7.2.2 Repeatability . 68

– 4 – 60731 © IEC:2011
8 Constructional requirements as related to PERFORMANCE CHARACTERISTICS . 69
8.1 Constructional requirements on CHAMBER ASSEMBLIES . 69
8.2 Constructional requirements on MEASURING ASSEMBLIES . 69
8.2.1 Adjustment of RESPONSE . 69
8.2.2 Display device . 69
8.2.3 Battery indication and compensation . 70
8.2.4 Input current threshold . 70
8.2.5 Automatic termination of measurement in the dose mode . 70
8.3 Constructional requirements on STABILITY CHECK DEVICES . 70
8.3.1 Output of the STABILITY CHECK DEVICES . 70
8.3.2 Constructional requirements particular to a radioactive type STABILITY
CHECK DEVICE . 71
8.3.3 Constructional requirements particular to an overall STABILITY CHECK
DEVICE . 71
8.4 Constructional requirements on PHANTOMS and build-up caps . 71
9 Marking . 72
9.1 Marking required on CHAMBER ASSEMBLY . 72
9.1.1 Information required in IEC 60601-1 . 72
9.1.2 Other information . 73
9.1.3 Compliance check . 73
9.2 Marking required on MEASURING ASSEMBLY . 73
9.2.1 CHAMBER ASSEMBLY in contact with the PATIENT . 73
9.2.2 CHAMBER ASSEMBLY not in contact with the PATIENT . 73
9.2.3 Each MEASURING ASSEMBLY . 73
9.2.4 MEASURING ASSEMBLY with a display scaled in dose . 74
9.2.5 Multi-range MEASURING ASSEMBLY . 74
9.2.6 MEASURING ASSEMBLY with more than one chamber . 74
9.2.7 Graphical symbols . 74
9.2.8 Compliance check . 74
9.3 Marking required on STABILITY CHECK DEVICE . 74
9.3.1 General . 74
9.3.2 STABILITY CHECK DEVICE containing a RADIOACTIVE SOURCE . 74
9.3.3 Device which contributes to protection against IONIZING RADIATION . 74
9.3.4 Compliance check . 74
9.4 Marking required on PHANTOM or build-up cap. 75
10 ACCOMPANYING DOCUMENTS . 75
10.1 ACCOMPANYING DOCUMENTS for CHAMBER ASSEMBLY . 75
10.1.1 INSTRUCTIONS FOR USE of CHAMBER ASSEMBLY . 75
10.1.2 Test sheet for CHAMBER ASSEMBLY . 77
10.1.3 Calibration certificate for CHAMBER ASSEMBLY . 77
10.2 ACCOMPANYING DOCUMENTS for MEASURING ASSEMBLY . 78
10.2.1 INSTRUCTIONS FOR USE of MEASURING ASSEMBLY . 78
10.2.2 Test sheet for MEASURING ASSEMBLY . 80
10.2.3 Calibration certificate for MEASURING ASSEMBLY . 80
10.3 ACCOMPANYING DOCUMENTS for STABILITY CHECK DEVICE . 81
10.3.1 INSTRUCTIONS FOR USE of STABILITY CHECK DEVICE . 81
10.3.2 Test sheet for STABILITY CHECK DEVICE. 81
10.3.3 Measurement certificate for STABILITY CHECK DEVICE . 81
10.4 ACCOMPANYING DOCUMENTS for PHANTOMS and build-up caps. 82

60731 © IEC:2011 – 5 –
Annex A (informative) Values, error and UNCERTAINTY . 84
Annex B (normative) Test equipment for cable microphony . 85
Annex C (normative) UNCERTAINTY OF MEASUREMENT . 86
Bibliography . 95
Index of defined terms used in this standard . 96

Figure 1 – Tolerance of depth in PHANTOM. 72
Figure 2 – Tolerance of lateral position in PHANTOM . 72
Figure A.1 – Graphical illustration of values, error and UNCERTAINTY . 84
Figure B.1 – Test equipment for cable microphony. 85
Figure C.1 – PROBABILITY DISTRIBUTIONS for the PERFORMANCE CHARACTERISTICS to be
within the LIMITS OF VARIATION ±L and the expression of their VARIANCES in terms of L . 88

Table 1 – REFERENCE CONDITIONS and STANDARD TEST CONDITIONS – CHAMBER ASSEMBLY . 26
Table 2 – REFERENCE CONDITIONS and STANDARD TEST CONDITIONS – MEASURING
ASSEMBLY . 27
Table 3 – Limits of PERFORMANCE CHARACTERISTICS at STANDARD TEST CONDITIONS –
CHAMBER ASSEMBLY . 27
Table 4 – Limits of PERFORMANCE CHARACTERISTICS at STANDARD TEST CONDITIONS –
MEASURING ASSEMBLY . 28
Table 5 – LIMITS OF VARIATION of PERFORMANCE CHARACTERISTICS for effects of
INFLUENCE QUANTITIES and INSTRUMENT PARAMETERS – CHAMBER ASSEMBLY . 29
Table 6 – LIMITS OF VARIATION of PERFORMANCE CHARACTERISTICS for effects of
INFLUENCE QUANTITIES and INSTRUMENT PARAMETERS – MEASURING ASSEMBLY . 31
Table 7 – LIMITS OF VARIATION of PERFORMANCE CHARACTERISTICS for effects of
INFLUENCE QUANTITIES and INSTRUMENT PARAMETERS – chamber and MEASURING
ASSEMBLIES combined . 32
Table C.1 – Estimate of COMBINED STANDARD UNCERTAINTY for performance of a
hypothetical dosimeter . 90
Table C.2 – A hypothetical example of the assessment of the UNCERTAINTIES on the
output measurement of an X-ray set using a FIELD-CLASS DOSIMETER . 94

– 6 – 60731 © IEC:2011
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL EQUIPMENT –
DOSIMETERS WITH IONIZATION CHAMBERS
AS USED IN RADIOTHERAPY
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60731 has been prepared by subcommittee 62C: Equipment for
radiotherapy, nuclear medicine and radiation dosimetry of IEC technical committee 62:
Electrical equipment in medical practice.
This third edition cancels and replaces the second edition published in 1997 and its
Amendment 1 (2002) and constitutes a technical revision. The technical modifications versus
the second edition of this standard concerns performance requirements of RADIOTHERAPY
DOSIMETERS intended for the measurement of ABSORBED DOSE TO WATER or AIR KERMA in heavy
ion RADIATION FIELDS and SCANNING-CLASS DOSIMETERS normally used for relative dose
distribution measurements with a SCANNING SYSTEM such as an automatic water PHANTOM.

60731 © IEC:2011 – 7 –
The text of this standard is based on the following documents:
FDIS Report on voting
62C/506/FDIS 62C/511/RVD
Full information on the voting for the approval of this standard can be found in the report of
voting indicated in the above table.
In this standard, the following print types are used:
– requirements, compliance with which can be tested, and definitions: in roman type;
– explanations, advice, general statements, exceptions and notes: in small roman type;
– test specifications: in italic type;
– terms used throughout this particular standard that have been listed in the Index of
defined terms and defined in Clause 3, or in other standards: SMALL CAPITALS.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 8 – 60731 © IEC:2011
INTRODUCTION
This International Standard is applicable to the performance of RADIOTHERAPY DOSIMETERS
with IONIZATION CHAMBERS as used in RADIOTHERAPY.
The effectiveness of treatment of PATIENTS receiving RADIOTHERAPY depends on the accuracy
of the dose of radiation received, as well as on the accuracy of their spatial distribution. An
excessive dose can lead to excessive tissue damage, while an insufficient dose will not
provide the therapeutic benefit sought. The equipment covered by this standard plays an
essential part in achieving the required accuracy.
This standard is not concerned with the safety aspects of dosimeters. The relevant IEC
standards covering safety depend upon the way in which the dosimeter is used:
– if it is used in the PATIENT environment, the requirements for safety applying to dosimeters
with IONIZATION CHAMBERS as used in RADIOTHERAPY are contained in IEC 60601-1;
– if it is not used in the PATIENT environment, then the safety requirements for dosimeters
with IONIZATION CHAMBERS as used in RADIOTHERAPY are contained in IEC 61010-1.
Dosimeters which comply with this standard should nevertheless be used in accordance with
the relevant national or international dosimetry protocol (code of practice). In particular,
measurements should be made to determine the ion collection efficiency and polarity effect of
the chamber under the exact conditions of use.

60731 © IEC:2011 – 9 –
MEDICAL ELECTRICAL EQUIPMENT –
DOSIMETERS WITH IONIZATION CHAMBERS
AS USED IN RADIOTHERAPY
1 Scope and object
1.1 Scope
This International Standard specifies the performance requirements of RADIOTHERAPY
DOSIMETERS, intended for the measurement of ABSORBED DOSE TO WATER or AIR KERMA (and
their rates and spatial distributions) in PHOTON, ELECTRON, proton or heavy ion RADIATION
FIELDS as used in RADIOTHERAPY.
The DOSE MONITORING SYSTEMS incorporated in RADIOTHERAPY treatment machines are not
covered by this standard, neither are the re-entrant IONIZATION CHAMBERS used for
BRACHYTHERAPY source calibration and constancy check devices.
This standard is applicable to the following types of dosimeter:
a) FIELD-CLASS DOSIMETERS normally used for
1) the measurement of KERMA or dose in a RADIATION BEAM, either in air or in a PHANTOM;
2) in vivo skin surface or intracavitary measurements of dose on PATIENTS.
b) REFERENCE-CLASS DOSIMETERS normally used for the calibration of FIELD-CLASS
DOSIMETERS;
NOTE REFERENCE-CLASS DOSIMETERS may be used as FIELD-CLASS DOSIMETERS.
c) SCANNING-CLASS DOSIMETERS normally used for relative dose distribution measurements
with a SCANNING SYSTEM such as an automatic water PHANTOM.
1.2 Object
The object of this standard is:
– to establish requirements for a satisfactory level of performance for RADIOTHERAPY
DOSIMETERS;
– to standardize methods for the determination of compliance with this level of performance.
Three levels of performance are specified:
– a lower level of performance applying to FIELD-CLASS DOSIMETERS;
– a higher level of performance applying to REFERENCE-CLASS DOSIMETERS;
– a specific level of performance applying to SCANNING-CLASS DOSIMETERS.
2 Normative references
The following referenced documents are indispensable for the application 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.
IEC 60417, Graphical symbols for use on equipment
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic
safety and essential performance

– 10 – 60731 © IEC:2011
IEC 60601-1-2:2007, Medical electrical equipment – Part 1-2: General requirements for basic
safety and essential performance – Collateral standard: Electromagnetic compatibility –
Requirements and tests
IEC 60601-1-3:2008, Medical electrical equipment – Part 1-3: General requirements for basic
safety and essential performance – Collateral Standard: Radiation protection in diagnostic X-
ray equipment
IEC 60601-2-8:2010, Medical electrical equipment – Part 2-8: Particular requirements for the
basic safety and essential performance of therapeutic X-ray equipment operating in the range
10 kV to 1 MV
IEC/TR 60788:2004, Medical electrical equipment – Glossary of defined terms
IEC 60976:2007, Medical electrical equipment – Medical electron accelerators – Functional
performance characteristics
IEC 61010-1:2010, Safety requirements for electrical equipment for measurement, control,
and laboratory use – Part 1: General requirements
IEC 61187, Electrical and electronic measuring equipment – Documentation
IEC 61267:2005, Medical diagnostic X-ray equipment – Radiation conditions for use in the
determination of characteristics
IEC 61676:2002, Medical electrical equipment – Dosimetric instruments used for non-invasive
measurement of X-ray tube voltage in diagnostic radiology
ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
ISO/IEC Guide 99:2007, International vocabulary of metrology – Basic and general concepts
and associated terms (VIM)
ISO 3534-1:2006, Statistics – Vocabulary and symbols – Part 1: General statistical terms and
terms used in probability
3 Terms and definitions
For the purpose of this International Standard the terms and definitions listed in index of
defined terms and the following apply.
NOTE The definitions given in this standard are generally in agreement with those in IEC TR 60788:2004 and ISO
International vocabulary of basic and general terms in metrology, except that some definitions have been made
more restricted. Any such special definitions should be regarded as applying only to this standard.
Any terms not defined in this standard have the meanings defined in the above publications or are assumed to be
in general scientific usage.
Throughout this standard:
– if no material is specified, the term "ABSORBED DOSE" or "dose" means "ABSORBED DOSE TO
WATER (in water)" and the term "KERMA" means "AIR KERMA (in air)";
– when the quantity "AIR KERMA (in air)" in units "Gy" is used, the quantity "EXPOSURE" in
units "C/kg" is also allowable;

60731 © IEC:2011 – 11 –
– the term “heavy ion“ addresses the range of nuclides from 2-He to 18-Ar in accordance
1)
with IAEA Technical Report 398 [2] .
3.1
RADIOTHERAPY DOSIMETER
equipment, consisting of a MEASURING ASSEMBLY and one ore more CHAMBER ASSEMBLIES, for
the measurement of AIR KERMA, ABSORBED DOSE, or their corresponding rates or spatial
distributions, in PHOTON, ELECTRON, proton and heavy ion radiation as used in RADIOTHERAPY
NOTE A RADIOTHERAPY DOSIMETER may include the following components:
– one or more STABILITY CHECK DEVICES;
– one or more PHANTOMS or build-up caps.
– one or more extension cables;
3.1.1
CHAMBER ASSEMBLY
IONIZATION CHAMBER and all other parts to which the chamber is permanently attached, except
the MEASURING ASSEMBLY
NOTE It includes the electrical fitting and any permanently attached cable.
3.1.1.1
IONIZATION CHAMBER
IONIZING RADIATION detector consisting of a chamber filled with air, in which an electric field
insufficient to produce gas multiplication, is provided for the collection at the electrodes of
ELECTRONS produced in the measuring volume of the
charges associated with the ions and the
detector by IONIZING RADIATION
NOTE 1 For this standard, the IONIZATION CHAMBER is considered to consist of the measuring volume, the
collecting electrode, the guard electrode (if any), the outer electrode (which consists of the chamber wall and
possibly a conducting coating), those parts of the insulator adjacent to the measuring volume, the build-up cap and
water-proof housing (if any).
NOTE 2 There are several categories of IONIZATION CHAMBER (see 3.1.1.1.1 to 3.1.1.1.7).
3.1.1.1.1
SHELL CHAMBER
3 3
IONIZATION CHAMBER with a measuring volume of between 0,1 cm and 1,0 cm bounded by a
rigid outer electrode mounted on a supporting stem
NOTE 1 The measuring volume is usually symmetrical about the axis of the stem and the chamber is intended to
be used with the axis of symmetry perpendicular to the axis of the RADIATION BEAM.
NOTE 2 There are two types of SHELL CHAMBER: THIMBLE CHAMBER and SPHERICAL CHAMBER (see 3.1.1.1.1.1 and
3.1.1.1.1.2).
3.1.1.1.1.1
THIMBLE CHAMBER
SHELL CHAMBER whose outer electrode takes the form of a rigid cylindrical wall closed at one
end and mounted at the other on the supporting stem
3.1.1.1.1.2
SPHERICAL CHAMBER
SHELL CHAMBER whose outer electrode takes the form of a rigid spherical wall mounted on the
supporting stem
—————————
1)
Figures in square brackets refer to the Bibliography.

– 12 – 60731 © IEC:2011
3.1.1.1.2
PARALLEL-PLATE CHAMBER
3 3
IONIZATION CHAMBER with a measuring volume of between approximately 0,01 cm and 0,5 cm
bounded by parallel electrodes
NOTE The chamber is intended to be used with the electrodes perpendicular to the axis of the RADIATION BEAM.
3.1.1.1.3
VENTED CHAMBER
IONIZATION CHAMBER constructed in such a way as to allow the air inside the measuring volume
to communicate freely with the atmosphere such that corrections to the RESPONSE for changes
in air density need to be made
3.1.1.1.4
SEALED CHAMBER
IONIZATION CHAMBER constructed in such a way as to restrict the pathway between the air
inside the measuring volume and the atmosphere sufficiently to ensure that the RESPONSE of
the chamber is independent of changes in ambient conditions over a period of time stated by
the MANUFACTURER
3.1.1.1.5
UNGUARDED IONIZATION CHAMBER
IONIZATION CHAMBER in which the guard conductor in the cable surrounding the centre (signal)
conductor terminates in the cable and does not extend into the stem or body of the CHAMBER
ASSEMBLY
3.1.1.1.6
PARTIALLY GUARDED IONIZATION CHAMBER
IONIZATION CHAMBER in which the guard conductor in the cable surrounding the centre (signal)
conductor extends well into the stem or body of the CHAMBER ASSEMBLY but does not enter the
air in the chamber
3.1.1.1.7
GUARDED IONIZATION CHAMBER
IONIZATION CHAMBER in which the guard conductor in the stem or body of the CHAMBER
ASSEMBLY is continuous with a guard electrode that is in contact with the air inside the
chamber
3.1.2
MEASURING ASSEMBLY
device to measure the charge (or current) from the IONIZATION CHAMBER and convert it into a
form suitable for displaying the values of dose or KERMA or their corresponding rates
3.1.3
STABILITY CHECK DEVICE
device which enables the stability of RESPONSE of the MEASURING ASSEMBLY and/or CHAMBER
ASSEMBLY to be checked
NOTE The STABILITY CHECK DEVICE may be a purely electrical device, or a RADIATION SOURCE, or it may include
both.
3.2
INDICATED VALUE
value of a quantity derived from the reading of an instrument together with any scale factors
indicated on the CONTROL PANEL of the instrument
NOTE The INDICATED VALUE is equivalent to the "uncorrected observations" shown in Figure A.1.

60731 © IEC:2011 – 13 –
3.3
TRUE VALUE
value of the physical quantity to be measured by an instrument
NOTE The TRUE VALUE is equivalent to the "value of MEASURAND" shown in Figure A.1.
3.4
CONVENTIONAL TRUE VALUE
value used instead of the TRUE VALUE when calibrating or determining the performance of an
instrument, since in practice the TRUE VALUE is unknown and unknowable
NOTE 1 The CONVENTIONAL TRUE VALUE will usually be the value determined by the WORKING STANDARD with which
the instrument under test is being compared.
NOTE 2 The possible bounds within which the CONVENTIONAL TRUE VALUE will lie are equivalent to the "values of
MEASURAND due to incomplete definition" shown in Figure A.1.
3.4.1
STANDARD
instrument which defines, represents physically, maintains or reproduces the unit
of measurement of a quantity (or a multiple or submultiple of that unit) in order to transfer it to
other instruments by comparison
3.4.1.1
NATIONAL STANDARD
STANDARD recognized by an official national decision as the basis for fixing the
values and UNCERTAINTIES in that country of all other STANDARDS of the given quantity
3.4.1.2
WORKING STANDARD
STANDARD which is traceable to the NATIONAL STANDARD
3.5
MEASURED VALUE
best estimate of the TRUE VALUE of a quantity, being derived from the INDICATED VALUE of an
instrument together with the application of all relevant CORRECTION FACTORS and the
CALIBRATION FACTOR
NOTE The MEASURED VALUE is the "final result of measurement" shown in Figure A.1.
3.5.1
ERROR OF MEASUREMENT
difference remaining between the MEASURED VALUE of a quantity and the TRUE VALUE of that
quantity
3.5.2
OVERALL UNCERTAINTY
UNCERTAINTY associated with the MEASURED VALUE
NOTE 1 I.e. it represents the bounds within which the ERROR OF MEASUREMENT is estimated to lie.
NOTE 2 For the purpose of this standard the OVERALL UNCERTAINTY may be taken as the EXPANDED UNCERTAINTY
corresponding to a confidence level of 95 % (see Annex A).
3.5.3
EXPANDED UNCERTAINTY
quantity defining an interval about the result of a measurement that may be expected to
encompass a large fraction of the distribution of values that could reasonably be attributed to
the MEASURAND
[ISO/IEC GUIDE 98-3:2008, 2.3.5]

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3.6
CORRECTION FACTOR
dimensionless multiplier which corrects the INDICATED VALUE of an instrument from its value
when operated under particular conditions to its value when operated under stated REFERENCE
CONDITIONS
3.7
INFLUENCE QUANTITY
any external quantity that may affect the performance of an instrument
NOTE See Table 5, Table 6 and Table 7 for examples of INFLUENCE QUANTITIES.
3.8
INSTRUMENT PARAMETER
any internal property of an instrument that may affect the performance of this instrument
NOTE See Table 5, Table 6 and Table 7 for examples of INSTRUMENT PARAMETERS.
3.9
REFERENCE VALUE
particular value of an INFLUENCE QUANTITY or INSTRUMENT PARAMETER chosen for the purposes
of reference
NOTE I.e. the value of an INFLUENCE QUANTITY (or INSTRUMENT PARAMETER) at which the CORRECTION FACTOR for
dependence on that INFLUENCE QUANTITY (or INSTRUMENT PARAMETER) is unity.
3.9.1
REFERENCE CONDITIONS
conditions under which all INFLUENCE QUANTITIES and INSTRUMENT PARAMETERS have their
REFERENCE VALUES
3.10
STANDARD TEST VALUES
value, values, or range of values of an INFLUENCE QUANTITY or INSTRUMENT PARAMETER, which
are permitted when carrying out calibrations or tests on another INFLUENCE QUANTITY or
INSTRUMENT PARAMETER
3.10.1
STANDARD TEST CONDITIONS
conditions under which all INFLUENCE QUANTITIES and INSTRUMENT PARAMETERS
...