EN 60731:1997

SLOVENSKI STANDARD
01-september-1998
Medical electrical equipment - Dosimeters with ionization chambers as used in
radiotherapy (IEC 60731:1997)
Medical electrical equipment - Dosimeters with ionization chambers as used in
radiotherapy
Medizinische elektrische Geräte - Dosimeter mit Ionisationskammern zur Anwendung in
der Strahlentherapie
Appareils électromédicaux - Dosimètres à chambre d'ionisation utilisés en radiothérapie
Ta slovenski standard je istoveten z: EN 60731:1997
ICS:
11.040.50 Radiografska oprema Radiographic equipment
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME
CEI
INTERNATIONALE
IEC
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
1997-07
Appareils électromédicaux –
Dosimètres à chambres d’ionisation
utilisés en radiothérapie
Medical electrical equipment –
Dosimeters with ionization chambers
as used in radiotherapy
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60731 © IEC:1997 – 3 –
CONTENTS
Page
FOREWORD . 11
INTRODUCTION . 13
Clause
1 Scope and object. 15
2 Normative references . 17
3 Terminology and definitions . 19
4 General requirements . 31
4.1 Performance requirements . 31
4.2 REFERENCE VALUES and STANDARD TEST VALUES . 31
4.3 General test conditions and methods . 33
4.3.1 STANDARD TEST CONDITIONS . 33
4.3.2 Test of components. 33
4.3.3 RATED or EFFECTIVE RANGE of DOSE (or KERMA) RATES. 33
4.3.4 Uncertainty of measurement . 35
4.3.5 Adjustments during test . 35
4.3.6 Test conditions particular to CHAMBER ASSEMBLIES. 35
4.3.7 Test conditions particular to MEASURING ASSEMBLIES. 35
4.3.8 Test conditions particular to STABILITY CHECK DEVICES . 37
4.3.9 Use of STABILITY CHECK DEVICES. 37
4.4 Summary tables . 37
Table 1 – REFERENCE CONDITIONS and STANDARD TEST CONDITIONS
1a – CHAMBER ASSEMBLY . 39
1b – MEASURING ASSEMBLY . 39
Table 2 – Limits of PERFORMANCE CHARACTERISTICS at STANDARD TEST CONDITIONS
2a – CHAMBER ASSEMBLY . 41
2b – MEASURING ASSEMBLY . 41
Table 3 – LIMITS OF VARIATION of PERFORMANCE CHARACTERISTICS for effects of
INFLUENCE QUANTITIES and INSTRUMENT PARAMETERS
3a – CHAMBER ASSEMBLY . 43
3b – MEASURING ASSEMBLY . 47
3c – CHAMBER and MEASURING ASSEMBLIES combined . 49
4.5 Classification of equipment according to LIMITS OF VARIATION. 49
4.5.1 FIELD-CLASS DOSIMETER. 49
4.5.2 REFERENCE-CLASS DOSIMETER. 49

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Clause Page
5 CHAMBER ASSEMBLY performance requirements. 51
5.1 General performance requirements for (RADIOTHERAPY) IONIZATION CHAMBERS . 51
5.1.1 CHAMBER ASSEMBLY LEAKAGE CURRENT without irradiation . 51
5.1.2 Stability. 51
5.1.3 STABILIZATION TIME . 53
5.1.4 Post-irradiation leakage. 53
5.1.5 RATED or EFFECTIVE RANGE of DOSE RATE (continuous radiation) . 55
5.1.6 Maximum RATED DOSE per pulse (pulsed radiation) . 57
5.1.7 STRAY RADIATION . 59
5.1.8 Guard/collector insulation. 61
5.1.9 Cable microphony . 61
5.1.10 Polarity of polarizing voltage effect . 61
5.1.11 Electromagnetic compatibility . 63
5.2 Performance requirements particular to SHELL CHAMBERS . 63
5.2.1 Dependence on radiation quality. 65
5.2.2 RATED RANGE of field sizes . 69
5.2.3 CHAMBER orientation. 73
5.3 Performance requirements particular to PARALLEL-PLATE CHAMBERS . 73
5.3.1 Dependence on radiation quality. 75
5.3.2 RATED RANGE of field sizes. 77
HAMBER
5.3.3 C orientation. 77
5.4 Performance requirements particular to VENTED CHAMBERS. 79
5.4.1 Atmospheric pressure change . 79
5.4.2 Temperature . 79
5.4.3 Humidity. 81
5.5 Performance requirements particular to SEALED CHAMBERS . 81
5.5.1 Atmospheric pressure change . 81
5.5.2 Temperature . 83
6. MEASURING ASSEMBLY performance requirements. 83
6.1 General performance requirements for (RADIOTHERAPY) DOSIMETERS . 85
6.1.1 EFFECTIVE RANGES . 85
6.1.2 RESOLUTION of the display. 85
6.1.3 Repeatability . 87
6.1.4 Long-term stability. 87
6.1.5 STABILIZATION TIME. 89
6.1.6 Electromagnetic compatibility . 89
6.2 Performance requirements particular to DOSIMETERS . 91
6.2.1 ZERO DRIFT . 91
6.2.2 ZERO SHIFT . 93
6.2.3 NON-LINEARITY . 95

60731 © IEC:1997 – 7 –
Clause Page
6.2.4 Range changing . 97
6.2.5 Dead time . 99
6.2.6 Temperature . 99
6.2.7 Humidity. 101
6.2.8 STRAY RADIATION effect. 101
6.2.9 Charge leakage. 103
6.2.10 DOSE RATE dependence of DOSIMETERS . 103
6.3 Performance requirements particular to DOSE RATEMETERS . 105
6.3.1 ZERO DRIFT . 105
6.3.2 ZERO SHIFT . 107
6.3.3 NON-LINEARITY . 109
6.3.4 Range changing . 111
6.3.5 RESPONSE TIME . 113
6.3.6 Temperature . 115
6.3.7 Humidity. 115
6.3.8 STRAY RADIATION effect. 117
6.4 Performance requirements particular to battery-operated MEASURING ASSEMBLIES 119
6.4.1 Operating battery life. 119
MEASURING
6.5 Performance requirements particular to supply mains-operated
ASSEMBLIES . 119
6.5.1 Mains voltage – static. 119
6.5.2 Mains voltage – variation during a measurement . 119
7 STABILITY CHECK DEVICE performance requirements . 121
7.1 General performance requirements for STABILITY CHECK DEVICES . 121
7.1.1 Long-term stability. 121
7.1.2 Repeatability . 121
8 Constructional requirements as related to PERFORMANCE CHARACTERISTICS . 123
8.1 Constructional requirements on CHAMBER ASSEMBLIES . 123
8.2 Constructional requirements on MEASURING ASSEMBLIES . 123
8.2.1 Adjustment of RESPONSE . 123
8.2.2 Display device. 123
8.2.3 Battery indication and compensation . 125
8.2.4 Input current threshold . 125
8.2.5 Automatic termination of measurement in the DOSE mode. 125
8.3 Constructional requirements on STABILITY CHECK DEVICES . 127
8.3.1 General constructional requirements on STABILITY CHECK DEVICES . 127
8.3.2 Constructional requirements particular to a radioactive type STABILITY
CHECK DEVICE . 127
8.3.3 Constructional requirements particular to an overall STABILITY CHECK
DEVICE. 127

60731 © IEC:1997 – 9 –
Clause Page
8.4 Constructional requirements on PHANTOMs and build-up caps. 127
8.4.1 PHANTOMs . 127
9 Marking . 129
9.1 Marking required on CHAMBER ASSEMBLY . 129
9.2 Marking required on MEASURING ASSEMBLY . 129
9.3 Marking required on STABILITY CHECK DEVICE . 131
9.4 Marking required on PHANTOM or build-up cap . 131
10 ACCOMPANYING DOCUMENTS . 133
10.1 ACCOMPANYING DOCUMENTS for CHAMBER ASSEMBLY. 133
10.1.1 INSTRUCTIONS FOR USE of CHAMBER ASSEMBLY. 133
10.1.2 Test sheet for CHAMBER ASSEMBLY . 137
10.1.3 Calibration certificate for CHAMBER ASSEMBLY . 137
10.2 ACCOMPANYING DOCUMENTS for MEASURING ASSEMBLY. 139
10.2.1 INSTRUCTIONS FOR USE of MEASURING ASSEMBLY. 139
10.2.2 Test sheet for MEASURING ASSEMBLY . 141
10.2.3 Calibration certificate for MEASURING ASSEMBLY . 143
10.3 ACCOMPANYING DOCUMENTS for STABILITY CHECK DEVICE. 143
10.3.1 INSTRUCTIONS FOR USE of STABILITY CHECK DEVICE . 143
STABILITY CHECK DEVICE
10.3.2 Test sheet for . 145
10.3.3 Measurement certificate for STABILITY CHECK DEVICE . 145
10.4 ACCOMPANYING DOCUMENTS for PHANTOMs and build-up caps. 147
10.4.1 INSTRUCTIONS FOR USE of PHANTOMs and build-up caps . 147
Figures
1 Graphical illustration of values, error and uncertainty . 149
2 Test equipment for cable microphony. 151
3 Tolerance of depth in PHANTOM . 153
4 Tolerance of lateral position in PHANTOM . 153
Annexes
A Uncertainty of measurements . 155
B Bibliography . 179
C Alphabetical index of defined terms. 181

60731 © IEC:1997 – 11 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
MEDICAL ELECTRICAL EQUIPMENT –
DOSIMETERS WITH IONIZATION CHAMBERS
AS USED IN RADIOTHERAPY
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The 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 second edition cancels and replaces the first edition published in 1982 and its amend-
ment 1 (1987) and constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
62C/170/FDIS 62C/197/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.
Annex A forms an integral part of this standard.
Annexes B and C are for information only.

60731 © IEC:1997 – 13 –
INTRODUCTION
This International Standard is applicable to the performance of 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; 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 physical contact with a PATIENT the particular requirements for safety
applying to DOSIMETERS with IONIZATION CHAMBERS as used in radiotherapy are contained in
IEC 60601-2-9. These requirements supplement the General requirements for safety of
MEDICAL ELECTRICAL EQUIPMENT
given in IEC 60601-1 (1988), amendment 1 (1991) and
amendment 2 (1995);
– if it is not used in physical contact with a PATIENT, then the safety requirements
for DOSIMETERS with IONIZATION CHAMBERS as used in radiotherapy are contained in
IEC 61010-1 (1990).
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:1997 – 15 –
MEDICAL ELECTRICAL EQUIPMENT –
DOSIMETERS WITH IONIZATION CHAMBERS
AS USED IN RADIOTHERAPY
1 Scope and object
1.1 Scope
1.1.1 This International Standard specifies the performance requirements of RADIOTHERAPY
DOSIMETERS, as defined in 3.1, intended for the measurement of ABSORBED DOSE TO WATER or
AIR KERMA (and their RATES) in photon or electron radiation fields as used in radiotherapy.
NOTE – 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.
1.1.2 The dose-monitoring systems incorporated in radiotherapy treatment machines are not
covered by this standard, neither are the re-entrant ion chambers used for brachytherapy
source calibration.
1.1.3 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) DOSE PATIENTS
in vivo skin surface or intracavitary measurements of on .
b) REFERENCE-CLASS DOSIMETERS normally used for the calibration of FIELD-CLASS
DOSIMETERS.
NOTE – REFERENCE-CLASS DOSIMETERS may be used as FIELD-CLASS DOSIMETERS.
1.2 Object
1.2.1 The object of this standard is:
a) to establish requirements for a satisfactory level of performance for RADIOTHERAPY
DOSIMETERS;
b) to standardize methods for the determination of compliance with this level of
performance.
1.2.2 Two 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.

60731 © IEC:1997 – 17 –
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. At the time of publication, the editions
indicated were valid. All normative documents are subject to revision, and parties to
agreements based on this International Standard are encouraged to investigate the possibility
of applying the most recent editions of the normative documents indicated below. Members of
IEC and ISO maintain registers of currently valid International Standards.
IEC 60051, Direct acting indicating analogue electrical measuring instruments and their
accessories
IEC 60417: 1973, Graphical symbols for use on equipment – Index, survey and compilation of
the single sheets
IEC 60601-1: 1988, Medical electrical equipment – Part 1: General requirements for safety
IEC 60601-2-9: 1987, Medical electrical equipment – Part 2: Particular requirements for the
safety, of dosimeters used in radiotherapy with electrically-connected radiation detectors
IEC 60788: 1984, Medical radiology – Terminology
IEC 61000-4-1: 1992, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 1: Overview of immunity tests – Basic EMC Publication
IEC 61000-4-2: 1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 2: Electrostatic discharge requirements – Basic EMC Publication
IEC 61000-4-3: 1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 3: Radiated electromagnetic field requirements
IEC 61000-4-4: 1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 4: Electrical fast transient /burst requirements – Basic EMC Publication
IEC 61000-4-5: 1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 5: Surge immunity requirements
IEC 61000-4-6: 1996, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 6: Conducted disturbances induced by radio frequency fields above
9 kHz
IEC 61000-4-11: 1994, Electromagnetic compatibility (EMC) – Part 4: Testing and
measurement techniques – Section 11: Voltage dips, short interruptions and voltage variation
immunity tests
IEC 61010-1: 1990, Safety requirements for electrical equipment for measurement control, and
laboratory use – Part 1: General requirements
IEC 61187: 1993, Electrical and electronic measuring equipment – Documentation
ISO, 1993, International Vocabulary of basic and general terms in metrology
ISO 3534-1: 1993, Statistics – Vocabulary and symbols – Part 1: Probability and general
statistical terms
ICRU 33: 1980, Radiation Quantities and Units

60731 © IEC:1997 – 19 –
3 Terminology and definitions
In this standard, the verbal form
– "shall" implies that compliance with a requirement is mandatory for compliance with the
standard;
– "should" implies that compliance with a requirement is strongly recommended but is not
mandatory for compliance with the standard;
– "may" implies that compliance with a requirement is permitted to be accomplished in a
particular manner for compliance with the standard.
The definitions given in this standard are generally in agreement with those in IEC 60788 and
ISO International vocabulary of basic and general terms in metrology, except that some
definitions have been made more restricted. Any such special definitions shall be regarded as
applying only to this standard.
Any terms not defined here in this clause have the meanings defined in the above publications
or are assumed to be in general scientific usage.
The defined terms are printed in SMALL CAPITALS throughout this standard.
For the purpose of this International Standard the following definitions apply:
IONIZATION CHAMBERS
3.1 (RADIOTHERAPY) DOSIMETER: Equipment which uses for the
measurement of AIR KERMA, ABSORBED DOSE, or the corresponding rates, in photon and electron
radiation as used in radiation therapy.
A RADIOTHERAPY DOSIMETER contains the following components:
– one or more CHAMBER ASSEMBLIES;
– a MEASURING ASSEMBLY (including possibly a separate display device);
– one or more STABILITY CHECK DEVICES (optional);
– one or more PHANTOMS or build-up caps (optional).
3.1.1 CHAMBER ASSEMBLY: The IONIZATION CHAMBER and all other parts to which the CHAMBER
is permanently attached, except the MEASURING ASSEMBLY. It includes the electrical fitting and
any permanently attached cable.
3.1.1.1 (IONIZATION) CHAMBER: An 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 charges associated with the ions and the electrons produced in
the measuring volume of the detector by IONIZING RADIATION.
IONIZATION CHAMBER
NOTE – For this standard, the is considered to consist of the measuring volume, the
CHAMBER
collecting electrode, the guard electrode (if any), the outer electrode (which consists of the 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).
There are several categories of IONIZATION CHAMBER:
a) SHELL CHAMBER: An 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. 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. There are two types of SHELL CHAMBER
:
1) THIMBLE CHAMBER: The outer electrode takes the form of a rigid cylindrical wall closed
at one end and mounted at the other on the supporting stem;

60731 © IEC:1997 – 21 –
2) SPHERICAL CHAMBER: The outer electrode takes the form of a rigid spherical wall
mounted on the supporting stem;
b) PARALLEL-PLATE CHAMBER: An IONIZATION CHAMBER with a measuring volume of between
3 3
0,01 cm and 0,5 cm bounded by parallel electrodes. The CHAMBER is intended to be used
with the electrodes perpendicular to the axis of the radiation beam;
c) VENTED CHAMBER: An 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;
d) SEALED CHAMBER: An 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;
e) UNGUARDED IONIZATION CHAMBER: An 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;
f) PARTIALLY GUARDED IONIZATION CHAMBER: An 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;
g) GUARDED IONIZATION CHAMBER: An 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: A 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: A 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: The value of a quantity derived from the scale 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 1.
3.3 TRUE VALUE: The 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 1.
3.4 CONVENTIONAL TRUE VALUE: The 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.
NOTES
1 The CONVENTIONAL TRUE VALUE will usually be the value determined by the WORKING STANDARD with which the
instrument under test is being compared.
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 1.
3.4.1 STANDARD: An 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.

60731 © IEC:1997 – 23 –
3.4.1.1 NATIONAL STANDARD: A STANDARD recognized by an official national decision as the
basis for fixing the value in that country of all other STANDARDS of the given quantity.
3.4.1.2 WORKING STANDARD: A STANDARD which is traceable to the NATIONAL STANDARD.
3.5 MEASURED VALUE: The 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 1.
3.5.1 ERROR OF MEASUREMENT: The 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, i.e. it
represents the bounds within which the ERROR OF MEASUREMENT is estimated to lie.
NOTE – 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: Defined in A.2.1.
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 (see table 3 for examples of INFLUENCE QUANTITIES).
3.8 INSTRUMENT PARAMETER: Any internal property of an instrument that may affect the
performance of this instrument (see table 3 for examples of INSTRUMENT PARAMETERS).
3.9 REFERENCE VALUE: Particular value of an INFLUENCE QUANTITY (or INSTRUMENT PARAMETER)
chosen for the purposes of reference, 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: A 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 have their STANDARD TEST VALUES.
3.11 INTRINSIC ERROR: Deviation of the MEASURED VALUE (i.e. the INDICATED VALUE, corrected
to REFERENCE CONDITIONS) from the CONVENTIONAL TRUE VALUE under STANDARD TEST
CONDITIONS.
3.11.1 RELATIVE INTRINSIC ERROR: The ratio of the INTRINSIC ERROR to the CONVENTIONAL TRUE
VALUE.
60731 © IEC:1997 – 25 –
3.12 PERFORMANCE CHARACTERISTIC: One of the quantities used to define the performance of
an instrument (e.g. RESPONSE, LEAKAGE CURRENT).
3.12.1 RESPONSE: For a CHAMBER ASSEMBLY with an associated MEASURING ASSEMBLY it is the
quotient of the INDICATED VALUE divided by the CONVENTIONAL TRUE VALUE at the position of the
REFERENCE POINT of the IONIZATION CHAMBER.
For a MEASURING ASSEMBLY on its own it is the quotient of the INDICATED VALUE divided by the
input charge or current.
For an IONIZATION CHAMBER on its own it is the quotient of the ionization charge or current
divided by the CONVENTIONAL TRUE VALUE.
3.12.1.1 SPECIFIED ENERGY RESPONSE: This is the RESPONSE of an IONIZATION CHAMBER
CHAMBER
calculated or measured for that type of as a function of radiation quality.
3.12.2 RESOLUTION (of the display): The smallest change of scale reading to which a
numerical value can be assigned without further interpolation:
– for an analogue display, the RESOLUTION is the smallest fraction of a scale interval that
can be determined by an observer under specified conditions;
– for a digital display, the RESOLUTION is the smallest significant increment of the reading.
3.12.3 EQUILIBRATION TIME: The time taken for a scale reading to reach and remain within a
specified deviation from its final steady value after a sudden change in an INFLUENCE QUANTITY
has been applied to the instrument.
3.12.4 RESPONSE TIME: The time taken for a scale reading to reach and remain within a
specified deviation from its final steady value after a sudden change in the quantity being
measured.
3.12.5 STABILIZATION TIME: The time taken for a stated PERFORMANCE CHARACTERISTIC to reach
and remain within a specified deviation from its final steady value after the MEASURING
ASSEMBLY has been switched on (or the polarizing voltage has been applied to the IONIZATION
CHAMBER).
3.12.6 (CHAMBER ASSEMBLY) LEAKAGE CURRENT: Any current in the signal path arising in the
CHAMBER ASSEMBLY which is not produced by ionization in the measuring volume.
NOTE – It is distinguished from ZERO DRIFT or ZERO SHIFT which arise in the MEASURING ASSEMBLY.
3.12.7 (MEASURING ASSEMBLY) ZERO DRIFT: A continuous change in the near zero scale
reading of the MEASURING ASSEMBLY in the "measure" condition with no signal present.
3.12.8 (MEASURING ASSEMBLY) ZERO SHIFT: A sudden change in the near zero scale reading of
the MEASURING ASSEMBLY when the setting control is changed from the "zero" condition to the
"measure" condition, with no signal present.
3.12.9 NON-LINEARITY: Deviation from linearity, quantified as follows: on each range the half
full scale reading M is taken as a reference; the input signal Q required to produce this
REFERENCE SCALE READING is measured. At another scale reading m produced by an input
signal q, the percentage deviation from linearity is given by:

60731 © IEC:1997 – 27 –
100·((m·Q / M·q) – 1)
NOTES
1 For a MEASURING ASSEMBLY set to the "DOSE" mode, the input signal is electric charge;
2 For a MEASURING ASSEMBLY set to the "DOSE RATE" mode, the input signal is electric current.
3.13 VARIATION: The relative difference, Δy/y, between the values of a PERFORMANCE
CHARACTERISTIC y, when one INFLUENCE QUANTITY (or INSTRUMENT PARAMETER) assumes
successively two specified values, the other INFLUENCE QUANTITIES (and INSTRUMENT
PARAMETERS) being kept constant at the STANDARD TEST VALUES (unless other values are
specified).
3.14 LIMITS OF VARIATION: The maximum VARIATION of a PERFORMANCE CHARACTERISTIC y,
permitted by this standard. If LIMITS OF VARIATION are stated as ± L %, the VARIATION Δy/y,
expressed as a percentage, shall remain in the range from – L % to + L %.
3.15 EFFECTIVE RANGE (of INDICATED VALUES): The range of INDICATED VALUES for which an
instrument complies with a stated performance; the maximum (minimum) EFFECTIVE INDICATED
VALUE is the highest (lowest) in this range.
The concept of EFFECTIVE RANGE may, for example, also be applied to scale readings and to
related quantities not directly indicated by the instrument e.g. input current.
NOTE – Referred to as EFFECTIVE RANGE in this standard.
3.16 RATED RANGE (of USE): The range of values of an INFLUENCE QUANTITY or INSTRUMENT
PARAMETER within which the instrument will operate within the LIMITS OF VARIATION. Its limits are
the maximum and minimum RATED values.
NOTE – Referred to as RATED RANGE in this standard.
3.16.1 MINIMUM RATED RANGE: This is the least range of an INFLUENCE QUANTITY or INSTRUMENT
PARAMETER over which the instrument shall operate within the specified LIMITS OF VARIATION in
order to comply with this standard.
3.17 REFERENCE POINT (of a CHAMBER): Point of an IONIZATION CHAMBER, which during the
calibration of the CHAMBER, is brought to coincidence with the point at which the CONVENTIONAL
TRUE VALUE is specified.
3.18 (MEDICAL ELECTRICAL) EQUIPMENT: Electrical equipment, provided with not more than one
connection to a particular SUPPLY MAINS and intended to diagnose, treat, or monitor the PATIENT
under medical supervision and which makes physical or electrical contact with the PATIENT
and/or transfers energy to or from the PATIENT and/or detects such energy transfer to or from
the PATIENT. (IEC 60601-1, 2.2.15)
3.18.1 SUPPLY MAINS: Permanently installed power source which may also be used to supply
electrical apparatus that is outside the scope of this standard. (IEC 60601-1, 2.12.10)
3.18.2 PATIENT: Living being (person or animal) undergoing medical investigation or dental
treatment. (IEC 60601-1, 2.12.4)
3.18.3 ACCESSIBLE METAL PART: Metal part of EQUIPMENT which can be touched without the
use of a TOOL. (IEC 60601-1, 2.1.2)
3.18.4 TOOL: Extra-corporeal object which may be used to secure or release fasteners or to
make adjustments. (IEC 60601-1, 2.12.12)

60731 © IEC:1997 – 29 –
3.19 CALIBRATION FACTOR: For a CHAMBER ASSEMBLY with an associated MEASURING ASSEMBLY
it is the factor which converts the INDICATED VALUE, corrected to stated REFERENCE CONDITIONS,
to the CONVENTIONAL TRUE VALUE at the position of the REFERENCE POINT of the IONIZATION
CHAMBER.
For an IONIZATION CHAMBER calibrated on its own without a specified MEASURING ASSEMBLY, the
CALIBRATION FACTOR converts the ionization charge or current, corrected to REFERENCE
CONDITIONS, to the CONVENTIONAL TRUE VALUE at the position of the REFERENCE POINT of the
CHAMBER (this is the reciprocal of RESPONSE under REFERENCE CONDITIONS).
3.20 REFERENCE INDICATED VALUE: The INDICATED VALUE at which the CALIBRATION FACTOR of
an instrument is determined.
3.21 REFERENCE SCALE READING: The scale reading corresponding to the REFERENCE
INDICATED VALUE.
3.22 FIELD-CLASS DOSIMETER: DOSIMETER whose performance and stability are sufficient for it
to be used to make ordinary routine measurements.
REFERENCE-CLASS DOSIMETER: DOSIMETER
3.23  whose performance and stability are sufficient
for it to be used to calibrate other DOSIMETERS.
3.24 TYPE TEST: Test normally carried out on a single instrument of each design.
NOTE – The purpose of the TYPE TEST is to verify whether or not the design of the instrument renders it capable
of meeting the requirements of the specification.
3.25 ROUTINE TEST: Test carried out on all instruments of a production or delivery batch.
3.26 ABSORBED DOSE TO WATER: Letter symbol D. Following the definition in C.4 of ICRU 33,
ABSORBED DOSE TO WATER is the quotient of dε by dm where dε is the mean energy imparted
by IONIZING RADIATION to water of mass dm. The unit of ABSORBED DOSE TO WATER is Gy (where
–1
1 Gy = 1 J·kg ).
&
3.26.1 ABSORBED DOSE RATE TO WATER: Letter symbol D. Following the definition in C.5 of
ICRU 33 ABSORBED DOSE RATE TO WATER is the quotient of dD by dt, where dD is the increment
of ABSORBED DOSE TO WATER in the time interval dt. The unit of ABSORBED DOSE RATE TO WATER
–1 –1 –1
is Gy·s (Gy·min ; Gy·h ).
3.27 AIR KERMA: Letter symbol K. Following the definition in C.6 of ICRU 33 AIR KERMA is the
quotient of dE by dm where dE is the sum of the initial kinetic energies of all the charged
tr tr
AIR
ionising particles liberated by uncharged ionising particles in air of mass dm. The unit of
–1
KERMA is Gy (where 1 Gy = 1 J·kg ).
&
3.27.1 AIR KERMA RATE: Letter symbol K. Following the definition in C.7 of ICRU 33 AIR
KERMA RATE is the quotient of dK by dt, where dK is the increment of AIR KERMA in the time
–1 –1 –1
interval dt. The unit of AIR KERMA RATE is Gy·s (Gy·min ; Gy·h ).
3.28 EXPOSURE: Letter symbol X. Following the definition in C.8 of ICRU 33 EXPOSURE is the
quotient of dQ by dm where dQ is the absolute value of the total charge of the ions of one sign
produced in air when all the electrons (negatrons and p
...