EN 61674:1997

SLOVENSKI STANDARD
01-september-1998
Medical electrical equipment - Dosimeters with ionization chambers and/or semi-
conductor detectors as used in x-ray diagnosis imaging (IEC 61674:1997)
Medical electrical equipment - Dosimeters with ionization chambers and/or semi-
conductor detectors as used in X-ray diagnostic imaging
Medizinische elektrische Geräte - Dosimeter mit Ionisationskammern und/oder
Halbleiterdetektoren für den Einsatz an diagnostischen Röntgeneinrichtungen
Appareils électromédicaux - Dosimètres à chambres d'ionisation et/ou à détecteurs à
semi-conducteurs utilisés en imagerie de diagnostic à rayonnement X
Ta slovenski standard je istoveten z: EN 61674:1997
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
Première édition
STANDARD
First edition
1997-10
Appareils électromédicaux –
Dosimètres à chambres d'ionisation et/ou
à détecteurs à semi-conducteurs utilisés
en imagerie de diagnostic à rayonnement X
Medical electrical equipment –
Dosimeters with ionization chambers and/or
semi-conductor detectors as used in X-ray
diagnostic imaging
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61674 © IEC:1997 – 3 –
CONTENTS
Page
FOREWORD . 7
INTRODUCTION . 9
Clause
1 Scope and object . 11
1.1 Scope. 11
1.2 Object . 11
2 Normative references. 11
3 Terminology and definitions . 13
4 General requirements. 27
4.1 Performance requirements. 27
4.2 REFERENCE VALUES and STANDARD TEST VALUES . 27
4.3 General test conditions . 29
4.3.1 STANDARD TEST CONDITIONS. 29
4.3.2 Statistical fluctuations. 29
4.3.3 STABILIZATION TIME. 29
4.3.4 Adjustments during test . 29
4.3.5 Batteries. 29
4.4 Constructional requirements as related to performance . 29
4.4.1 Components. 29
4.4.2 Display. 31
4.4.3 Indication of battery condition . 31
4.4.4 Indication of polarizing voltage failure . 31
4.4.5 Over-ranging. 31
4.4.6 Indication of reset or other inactive condition . 33
4.4.7 MEASURING ASSEMBLIES with multiple DETECTOR ASSEMBLIES . 33
4.4.8 Radioactive STABILITY CHECK DEVICE. 33
4.5 Uncertainty of measurement . 35
5 Limits of PERFORMANCE CHARACTERISTICS . 35
5.1 RELATIVE INTRINSIC ERROR . 35
5.2 Repeatability. 35
5.2.1 Repeatability in the ATTENUATED BEAM. 37
UNATTENUATED BEAM
5.2.2 Repeatability in the . 37
5.3 RESOLUTION of reading. 37
5.4 STABILIZATION TIME . 37
5.5 Effect of pulsed radiation on AIR KERMA and AIR KERMA LENGTH measurements . 37
5.6 Reset on AIR KERMA and AIR KERMA LENGTH ranges . 39
5.7 Effects of LEAKAGE CURRENT. 39
5.7.1 On all AIR KERMA RATE ranges. . 39
5.7.2 On all AIR KERMA and AIR KERMA LENGTH ranges. 39
5.8 Stability. 39
5.8.1 Long term stability . 39
5.8.2 Accumulated dose stability . 39
5.9 Measurements with a radioactive STABILITY CHECK DEVICE. 41

61674 © IEC:1997 – 5 –
Clause Page
6 LIMITS OF VARIATION for effects of INFLUENCE QUANTITIES . 41
6.1 Energy dependence of RESPONSE. 41
6.2 AIR KERMA RATE dependence of AIR KERMA and AIR KERMA LENGTH
measurements. 43
6.2.1 MEASURING ASSEMBLY . 43
6.2.2 IONIZATION CHAMBER – Recombination losses . 43
6.3 Dependence of DETECTOR RESPONSE on angle of incidence of radiation . 45
6.3.1 For non-CT DETECTORS. 45
6.3.2 For CT DETECTORS. 45
6.4 Operating voltage. 45
6.4.1 For mains-operated DOSIMETERS. 45
6.4.2 For battery-operated DOSIMETERS. 45
6.4.3 For mains rechargeable, battery-operated DOSIMETERS . 45
6.5 Air pressure. 47
6.6 Air pressure EQUILIBRATION TIME of the RADIATION DETECTOR . 47
6.7 Temperature and humidity . 47
6.8 Electromagnetic compatibility. 49
6.8.1 Electrostatic discharge. 49
6.8.2 Radiated electromagnetic fields . 49
6.8.3 Conducted disturbances induced by bursts and radio frequencies . 51
6.8.4 Voltage dips, short interruptions and voltage variations . 51
6.9 Field size. 51
6.10 EFFECTIVE LENGTH and spatial uniformity of RESPONSE of CT DOSIMETERS . 53
7 Marking. 53
7.1 DETECTOR ASSEMBLY . 53
7.2 MEASURING ASSEMBLY. 53
7.3 Radioactive STABILITY CHECK DEVICE . 55
8 ACCOMPANYING DOCUMENTS . 55
Tables
EFERENCE STANDARD TEST CONDITIONS
1R and . 57
2 Number of readings required to detect true differences Δ (95 % confidence level)
between two sets of instrument readings. 59
3RELATIVE INTRINSIC ERROR, I, for measurements in the ATTENUATED BEAM. 59
4RELATIVE INTRINSIC ERROR, I, for measurements in the UNATTENUATED BEAM and
in mammography. 61
5 Maximum values for the COEFFICIENT OF VARIATION, v . 61
max
6 Maximum values for the COEFFICIENT OF VARIATION, v . 61
max
7LIMITS OF VARIATION for the effects of INFLUENCE QUANTITIES . 63
Figure 1 – Limits on the RELATIVE INTRINSIC ERROR for AIR KERMA RATE measurements
in the ATTENUATED BEAM. 65
Annexes
A Bibliography . 67
B Index of defined terms . 69

61674 © IEC:1997 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_________
MEDICAL ELECTRICAL EQUIPMENT –
DOSIMETERS WITH IONIZATION CHAMBERS AND/OR
SEMI-CONDUCTOR DETECTORS AS USED
IN X-RAY DIAGNOSTIC IMAGING
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 61674 has been prepared by subcommittee 62C: Equipment for
radiotherapy, nuclear medicine and radiation dosimetry, of IEC technical committee 62:
Electrical equipment in medical practice. The text of this standard is based on the following
documents:
FDIS Report on voting
62C/195/FDIS 62C/207/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
Annexes A and B are for information only.

61674 © IEC:1997 – 9 –
INTRODUCTION
Diagnostic radiology is the largest contributor to man-made ionizing radiation to which the
public is exposed. The reduction in the exposure received by PATIENTS undergoing medical
radiological examinations or procedures has therefore become a central issue in recent years.
The PATIENT dose will be minimized when the X-ray producing equipment is correctly adjusted
for image quality and radiation output. These adjustments require that the routine
measurement of AIR KERMA, AIR KERMA LENGTH and/or AIR KERMA RATE be made accurately. The
equipment covered by this standard plays an essential part in achieving the required accuracy.
The DOSIMETERS used for adjustment and control measurements must be of satisfactory quality
and must therefore fulfil the special requirements laid down in this standard.

61674 © IEC:1997 – 11 –
MEDICAL ELECTRICAL EQUIPMENT –
DOSIMETERS WITH IONIZATION CHAMBERS AND/OR
SEMI-CONDUCTOR DETECTORS AS USED
IN X-RAY DIAGNOSTIC IMAGING
1 Scope and object
1.1 Scope
This International Standard specifies the performance and some related constructional
requirements of DIAGNOSTIC DOSIMETERS, as defined in 3.1, intended for the measurement
of AIR KERMA, AIR KERMA LENGTH or AIR KERMA RATE, in photon radiation fields used
in RADIOGRAPHY, including MAMMOGRAPHY, RADIOSCOPY and COMPUTED TOMOGRAPHY (CT), for
X-rays with generating potentials not greater than 150 kV.
This International Standard is applicable to the performance of DOSIMETERS with IONIZATION
CHAMBERS and/or SEMI-CONDUCTOR DETECTORS as used in X-ray diagnostic imaging.
1.2 Object
The object of this standard is:
1) to establish requirements for a satisfactory level of performance for DIAGNOSTIC DOSIMETERS,
and
2) to standardize the methods for the determination of compliance with this level of
performance.
This standard is not concerned with the safety aspects of DOSIMETERS DIAGNOSTIC
. The
DOSIMETERS covered by this standard are not intended for use in physical contact with the
PATIENT and, therefore, the requirements for electrical safety applying to them are contained in
IEC 61010-1.
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 60417: 1973, Graphical symbols for use on equipment – Index, survey and compilation of
the single sheets
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 immunity test – Basic EMC publication

61674 © IEC:1997 – 13 –
IEC 61000-4-3: 1995, Electromagnetic compatibility (EMC) – Part 4:Testing and measurement
techniques – Section 3: Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4: 1995, Electromagnetic compatibility (EMC) – Part 4:Testing and measurement
techniques – Section 4: Electrical fast transient/burst immunity test – Basic EMC publication
IEC 61000-4-5: 1995, Electromagnetic compatibility (EMC) – Part 4:Testing and measurement
techniques – Section 5: Surge immunity tests
IEC 61000-4-6: 1996, Electromagnetic compatibility (EMC) – Part 4:Testing and measurement
techniques – Section 6: Immunity to conducted disturbances induced by radio frequency fields
IEC 61000-4-11: 1994, Electromagnetic compatibility (EMC) – Part 4:Testing and measurement
techniques – Section 11: Voltage dips, short interruptions and voltage variations immunity
test – Basic EMC publication
IEC 61187: 1993, Electrical and electronic measuring equipment – Documentation
IEC 61267: 1994, Medical diagnostic X-ray equipment – Radiation conditions for use in the
determination of characteristics
3 Terminology and definitions
In this standard the auxiliary verb:
– "shall" implies that compliance with a requirement is 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 international standard are generally in agreement with those in:
– IEC 60788:1984, Medical radiology – Terminology
– ISO:1993, International vocabulary of basic and general terms in metrology, 2nd. ed.;
but some definitions have been given a more restricted meaning. Such special definitions shall
be regarded as applying only to this standard.
Terms not defined in this clause have the meanings defined in the above publications or are
assumed to be terms of general scientific usage. An alphabetical list of the defined terms is
given in annex B.
For the purpose of this international standard the following definitions apply:
3.1
(DIAGNOSTIC) DOSIMETER
Equipment which uses IONIZATION CHAMBERS and/or SEMI-CONDUCTOR DETECTORS for the
measurement of AIR KERMA, AIR KERMA LENGTH and/or AIR KERMA RATE in the beam of an X-ray
machine used for diagnostic medical radiological examinations.
A DIAGNOSTIC DOSIMETER contains the following components:
– one or more DETECTOR ASSEMBLIES which may or may not be an integral part of the
MEASURING ASSEMBLY;
–a MEASURING ASSEMBLY;
– one or more STABILITY CHECK DEVICES (optional).

61674 © IEC:1997 – 15 –
3.1.1
DETECTOR ASSEMBLY
RADIATION DETECTOR and all other parts to which the RADIATION DETECTOR is permanently
attached, except the MEASURING ASSEMBLY.
NOTE – The DETECTOR ASSEMBLY normally includes:
– the RADIATION DETECTOR and the stem (or body) on which the RADIATION DETECTOR is permanently mounted
(or embedded);
– the electrical fitting and any permanently attached cable or pre-amplifier.
3.1.1.1.
RADIATION DETECTOR
Element which transduces AIR KERMA, AIR KERMA LENGTH or AIR KERMA RATE into a measurable
electrical signal. It may be either an IONIZATION CHAMBER or a SEMI-CONDUCTOR DETECTOR:
1) IONIZATION CHAMBER: Ionization detector consisting of a chamber filled with air, in which an
electric field insufficient to induce gas multiplication is provided for the collection, at the
electrodes, of charges associated with the ions and electrons produced in the sensitive
volume of the detector by ionizing radiation. The chamber is constructed in such a way as to
allow the air inside the measuring volume to communicate freely with the atmosphere so
that corrections to the RESPONSE for changes in air density need to be made.
2) 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 so that corrections
to the RESPONSE for changes in air density need to be made.
NOTE - Sealed chambers are not suitable, because the necessary wall thickness of a sealed chamber may cause
an unacceptable energy dependence of the RESPONSE and because the long term stability of sealed chambers is not
guaranteed.
3) SEMI-CONDUCTOR DETECTOR: Either a) and/or b):
a) semi-conductor device operating in the shorted junction mode that utilizes the production
and motion of excess free charge carriers in the semi-conductor for the detection and
measurement of incident ionizing radiation;
b) scintillator material optically coupled to a semi-conductor photodiode operating in the
shorted junction mode, in which assembly incident ionizing radiation is first converted to
light and then to an electrical signal.
3.1.2
MEASURING ASSEMBLY
Device to convert the output from the DETECTOR ASSEMBLY into a form suitable for the display of
the value(s) of AIR KERMA, AIR KERMA LENGTH or AIR KERMA RATE.
3.1.3
STABILITY CHECK DEVICE
Device, either separate or integral part of the DIAGNOSTIC DOSIMETER, which enables the
stability of the RESPONSE of the RADIATION DETECTOR and/or MEASURING ASSEMBLY to be
checked.
NOTE - The STABILITY CHECK DEVICE may be a purely electrical device, or a radiation source, or it may include both.
3.1.4
CT DOSIMETER
DIAGNOSTIC DOSIMETER which uses long narrow IONIZATION CHAMBERS and/or SEMI-CONDUCTOR
DETECTORS for the measurement of AIR KERMA integrated along the length of the DETECTOR
when the DETECTOR is exposed to a cross-sectional X-ray scan of a computed tomographic
machine.
61674 © IEC:1997 – 17 –
A CT DOSIMETER contains the following components:
– one or more DETECTOR ASSEMBLIES;
–a MEASURING ASSEMBLY.
3.1.5
CT DETECTOR
RADIATION DETECTOR which is used for CT dosimetry.
3.2
INDICATED VALUE
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.
3.3
TRUE VALUE
Value of the physical quantity to be measured by an instrument.
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.
NOTE - The CONVENTIONAL TRUE VALUE will usually be the value determined by the STANDARD with which the
instrument under test is compared.
3.4.1
STANDARD
Instrument which defines, represents physically, maintains or reproduces the unit of
measurement of a quantity (or a multiple or sub-multiple of that unit) in order to transfer it to
other instruments by comparison.
3.5
MEASURED VALUE
Best estimate of the TRUE VALUE of a quantity, derived from the INDICATED VALUE of an
instrument together with the application of all relevant CORRECTION FACTORS.
3.5.1
ERROR OF MEASUREMENT
Difference 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. representing the bounds within which the
ERROR OF MEASUREMENT is estimated to lie (see also 4.5).
3.5.3
EXPANDED UNCERTAINTY
Quantity defining the interval about the result of a measurement within which the values that
could reasonably be attributed to the measurand may be expected to lie with a higher degree of
confidence.
61674 © IEC:1997 – 19 –
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 (e.g. ambient
temperature, radiation quality, etc.).
3.8
INSTRUMENT PARAMETER
Any internal property of an instrument that may affect the performance of this instrument.
3.9
REFERENCE VALUE
Particular value of an INFLUENCE QUANTITY (or INSTRUMENT PARAMETER) chosen for the purpose
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
Value(s), 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
Ratio of the INTRINSIC ERROR to the CONVENTIONAL TRUE VALUE.
3.12
PERFORMANCE CHARACTERISTIC
One of the quantities used to define the performance of an instrument (e.g. RESPONSE,
LEAKAGE CURRENT).
61674 © IEC:1997 – 21 –
3.12.1
RESPONSE
Quotient of the INDICATED VALUE by the CONVENTIONAL TRUE VALUE.
3.12.2
RESOLUTION OF THE DISPLAY
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
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
Time taken for a stated PERFORMANCE CHARACTERISTIC to reach and remain within a specified
deviation from its final steady value, after the DOSIMETER has been switched on (and, if the
RADIATION DETECTOR is an IONIZATION CHAMBER, after the polarizing voltage has been applied).
3.12.6
LEAKAGE CURRENT
Any current in the signal path arising in the DETECTOR and/or MEASURING ASSEMBLY which is not
produced by ionization in the RADIATION DETECTOR.
3.13
VARIATION
Relative difference, Δy/y, between the values of a PERFORMANCE CHARACTERISTIC, y, when one
INFLUENCE QUANTITY (or INSTRUMENT PARAMETER) successively assumes 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
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 %.

61674 © IEC:1997 – 23 –
3.15
EFFECTIVE RANGE (of INDICATED VALUES)
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 also be applied to scale readings and to related
quantities that are not directly indicated by the instrument, for example the input signal.
NOTE 1 – The EFFECTIVE RANGE of INDICATED VALUES is referred to as EFFECTIVE RANGE in this standard.
NOTE 2 – For CT DOSIMETERS the EFFECTIVE RANGE of AIR KERMA LENGTH need not be stated as the largest range of
AIR KERMA LENGTH values that it is possible to measure with the equipment. Rather, it may be restricted to the range
which is of practical interest to the USER, e.g. 1μGy·m to 2mGy·m.
3.16
RATED RANGE (of USE)
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 - The RATED RANGE of USE is referred to as RATED RANGE in this standard.
3.16.1
MINIMUM RATED RANGE
The least range of an INFLUENCE QUANTITY or INSTRUMENT PARAMETER within which the
instrument operates within the specified LIMITS OF VARIATION in order to comply with this
standard.
3.17
REFERENCE POINT (of a RADIATION DETECTOR)
Point of a RADIATION DETECTOR which, during the calibration of the DETECTOR, 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: 1988,
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: 1988, 2.12.10]
3.18.2
PATIENT
Living being (person or animal) undergoing medical investigation or treatment.
[IEC 60601-1: 1988, 2.12.4]
3.18.3
ACCESSIBLE METAL PART
EQUIPMENT TOOL
Metal part of which can be touched without the use of a .
[IEC 60601-1: 1988, 2.1.2]
61674 © IEC:1997 – 25 –
3.18.4
TOOL
Extra-corporeal object which may be used to secure or release fasteners or to make
adjustments. [IEC 60601-1: 1988, 2.12.12]
3.19
UNATTENUATED BEAM
X-ray beam incident on the PATIENT or phantom.
3.19.1
UNATTENUATED BEAM QUALITY
Radiation quality of the X-ray beam incident on the PATIENT or phantom in the absence of the
PATIENT or phantom, i.e. in free air.
3.20
ATTENUATED BEAM
X-ray beam exiting the PATIENT or phantom.
3.20.1
ATTENUATED BEAM QUALITY
Radiation quality of the X-ray beam exiting the PATIENT or phantom.
3.21
RATED LENGTH
Length along the axis of the CT DETECTOR within which the DETECTOR performs to its
specification.
3.21.1
EFFECTIVE LENGTH
Length along the axis of the CT DETECTOR between the two points at which the RESPONSE has
fallen to 50 % of its maximum value (at the centre).
3.22
AIR KERMA (letter symbol K)
Quotient of dE by dm, where dE is the sum of the initial kinetic energies of all the charged
tr tr
ionizing particles liberated by uncharged ionizing particles in air of mass dm. The unit of AIR
–1
KERMA is Gy (1 Gy = 1 J⋅kg ), (see C.6 of ICRU 33 ).
3.22.1
&
AIR KERMA RATE (letter symbol K )
Quotient of dK by dt, where dK is the increment of AIR KERMA in the time interval dt. The unit of
AIR KERMA RATE is Gy/s (Gy/min; Gy/h), (see C.7 of ICRU 33).
3.22.2
AIR KERMA LENGTH (letter symbol K.I)
For any straight line passing through the cross sectional X-ray scan of a CT machine, AIR
KERMA LENGTH is the infinite integral of the product of AIR KERMA and elemental length along
this line. The unit of AIR KERMA LENGTH is Gy·m (mGy·m).

61674 © IEC:1997 – 27 –
3.23
(X-RAY) TUBE VOLTAGE
Potential difference applied to an X-ray tube between the cathode, i.e. the electron emitter, and
the anode.
3.24
COEFFICIENT OF VARIATION
Standard deviation of a set of readings expressed as a percentage of the mean value of these
readings.
3.25
ACCOMPANYING DOCUMENTS
Documents provided with an installation, equipment, associated equipment or accessory and
containing important information for the assembler, installer and USER, particularly regarding
safety (rm-82-01 of IEC 60788).
3.25.1
INSTRUCTIONS FOR USE
Those parts of ACCOMPANYING DOCUMENTS giving the necessary information for safe and proper
use and operation of the equipment (rm-82-02 of IEC 60788 modified).
3.25.2
USER
When used in an IEC standard on electromedical equipment, organization or individual
responsible for the use and maintenance of the equipment (rm-85-01 of IEC 60788).
3.26
OPERATOR
Person utilizing an equipment individually with or without the aid of an assistant, who controls
some or all functions of the equipment in his presence (rm-85-02 of IEC 60788).
3.27
MANUFACTURER
Listed in rm-85-03 of IEC 60788 as a term without definition.
4 General requirements
4.1 Performance requirements
In clauses 5 and 6 the performance requirements are stated for a complete DIAGNOSTIC
DOSIMETER including both the DETECTOR ASSEMBLY and MEASURING ASSEMBLY. For a DOSIMETER
designed to operate with one or more DETECTOR ASSEMBLIES, each combination of the
MEASURING ASSEMBLY DETECTOR ASSEMBLY
and shall comply with the requirements in 4.4, and in
clauses 5 and 6 relevant to this combination.
4.2 REFERENCE VALUES and STANDARD TEST VALUES
These values are as given in table 1.

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4.3 General test conditions
4.3.1 STANDARD TEST CONDITIONS
The STANDARD TEST CONDITIONS listed in table 1 shall be met during the test procedure except:
a) for the INFLUENCE QUANTITY under investigation;
b) where local conditions of temperature and relative humidity are outside the STANDARD TEST
CONDITIONS. In this case the tester shall demonstrate the validity of the test results.
4.3.2 Statistical fluctuations
At low AIR KERMA and AIR KERMA RATES the magnitude of the statistical fluctuations of the
instrument’s reading due to the random nature of the radiation alone may be a significant
fraction of the VARIATION of the mean reading permitted in the test. A sufficient number of
readings shall be taken to ensure that the mean value of such readings may be estimated with
sufficient precision to demonstrate compliance or non-compliance with the test requirements.
Table 2 provides guidance on the number of readings required to determine true differences
between two sets of instrument readings at the 95 % confidence level. The number of readings,
n, required as a function of the percentage difference Δ of the mean values and the
COEFFICIENT OF VARIATION, v, of the sets of readings (assumed to be equal for each set) are
listed.
4.3.3 STABILIZATION TIME
The instrument shall be switched on for at least the STABILIZATION TIME quoted by the
manufacturer, before the start of the compliance test.
In addition, if the RADIATION DETECTOR is an IONIZATION CHAMBER then it should be allowed to
attain thermal equilibrium with the environment and should have the polarizing voltage applied
for a period of time equal to or greater than the specified STABILIZATION TIME.
4.3.4 Adjustments during test
Compliance tests shall be performed with the instrument ready for use, after the STABILIZATION
TIME
and after making any necessary preliminary adjustments. During the tests, adjustments
may be repeated at intervals as long as they do not interfere with the effect to be verified. For
example, zero setting is not permitted during tests for measuring the LEAKAGE CURRENT.
4.3.5 Batteries
Battery-operated instruments shall be equipped with fresh batteries, of the type specified by the
MANUFACTURER.
4.4 Constructional requirements as related to performance
4.4.1 Components
DIAGNOSTIC DOSIMETER DETECTOR DOSIMETER
If a has several ranges or scales or if the consists
of several components, all ranges, scales and components shall be unmistakably and
unambiguously identified.
Compliance with the constructional requirement on components shall be checked by
inspection.
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4.4.2 Display
4.4.2.1 Units
The indicated unit shall be that of the measuring quantity: AIR KERMA, AIR KERMA LENGTH or AIR
KERMA RATE i.e. Gy, Gy·m or Gy/s respectively, with SI prefix e.g. m or μ.
Compliance with the constructional requirement on components shall be checked by
inspection.
4.4.2.2 Analogue displays
Analogue displays shall have a linear scaling which is designed such that the ratio of the full-
scale values of two subsequent measurement ranges does not exceed a ratio of 10:3.
Compliance with the constructional requirement on components shall be checked by
inspection.
4.4.2.3 Digital display
Digital displays whose improper function can result in non-perceptible faults (e.g. no light
emission from certain segments of a segment display) shall be provided with a means of
reliably checking their proper function.
Compliance with the constructional requirement on display shall be checked by inspection.
4.4.3 Indication of battery condition
Battery-operated DOSIMETERS shall be provided with a low battery indication for any battery
voltage below the RATED RANGE.
Compliance with the constructional requirement on indication of battery condition shall be
checked by inspection.
4.4.4 Indication of polarizing voltage failure
DOSIMETERS intended for use with IONIZATION CHAMBERS shall be provided with a means of
indicating if the polarizing voltage does not meet the MANUFACTURER'S requirement for
satisfactory operation.
Compliance with the constructional requirement on polarizing voltage shall be checked by
inspection.
4.4.5 Over-ranging
NOTE - When testing for compliance with the requirement on over-ranging it is not necessary to use REFERENCE
CONDITIONS.
4.4.5.1 On all AIR KERMA RATE ranges, the DOSIMETER shall clearly indicate over-range when
the full scale reading is exceeded, and shall remain indicating over-range for all AIR KERMA
RATES up to 1 Gy/s.
AIR KERMA RATE
Compliance shall be checked for each allowable combination of range and
DETECTOR ASSEMBLY with a full scale reading of 10 mGy/s or less, by exposing the relevant
RADIATION DETECTOR in any suitable X-ray beam at the AIR KERMA RATE for which the display
reads just below the stated full scale, then proceeding to:
a) increase the AIR KERMA RATE slowly but continuously until the display shows over-range;
b) increase the AIR KERMA RATE further in discrete decade steps until 10 mGy/s is exceeded,
AIR KERMA RATES
checking that the display indicates over-range for each of these .

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Compliance shall be checked for each allowable combination of AIR KERMA RATE range and
DETECTOR ASSEMBLY with a full scale reading of more than 10 mGy/s as described above, or by
conducting an electrical test on the MEASURING ASSEMBLY and verifying that, for ion currents
corresponding to AIR KERMA RATES of up to 1 Gy/s or 10 times the full scale reading, the
DOSIMETER clearly indicates an over-range condition.
4.4.5.2 On all AIR KERMA and AIR KERMA LENGTH ranges, the DOSIMETER shall clearly indicate
over-range when the full scale reading is exceeded.
Compliance shall be checked on each AIR KERMA and AIR KERMA LENGTH range by exposing the
relevant RADIATION DETECTOR until the display reads just below the stated full scale. The
irradiation should then be continued in AIR KERMA or AIR KERMA LENGTH steps approximately
equal to the display RESOLUTION
for the range in use, until the display shows over-range. An
equivalent electrical test can be made on the MEASURING ASSEMBLY.
4.4.5.3 On all AIR KERMA and AIR KERMA LENGTH ranges the DOSIMETER shall clearly indicate
over-range when the RATED RANGE of AIR KERMA RATE is exceeded, unless it is able to measure
AIR KERMA at an AIR KERMA RATE of at least:
– 1 Gy/s in the conventional diagnostic UNATTENUATED BEAM;
– 10 mGy/s in the conventional diagnostic ATTENUATED BEAM;
– 100 mGy/s in the mammographic UNATTENUATED BEAM;
– 500 mGy/s in the computed tomographic UNATTENUATED BEAM.
Compliance shall be checked on each AIR KERMA and AIR KERMA LENGTH range by exposing the
relevant RADIATION DETECTOR to an AIR KERMA RATE of 10 % above the RATED RANGE and
checking that the DOSIMETER clearly indicates an over-range condition.
4.4.6 Indication of reset or other inactive condition
During any period of time when the DOSIMETER is inactive, e.g. following the reset procedure,
this state shall be indicated.
Compliance with this constructional requirement shall be checked by inspection.
4.4.7 MEASURING ASSEMBLIES with multiple DETECTOR ASSEMBLIES
For MEASURING ASSEMBLIES displaying AIR KERMA or AIR KERMA RATE using multiple DETECTOR
ASSEMBLIES connected to a single display, only the signal from a single detector assembly shall
be displayed on the MEASURING ASSEMBLY at any one time.
Compliance with the constructional requirement on MEASURING ASSEMBLIES with multiple
DETECTOR ASSEMBLIES shall be checked by inspection.
4.4.8 Radioactive STABILITY CHECK DEVICE
The half-life of the radionuclide of a STABILITY CHECK DEVICE (if provided) shall be greater than
five years.
Compliance shall be checked by inspection.

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4.5 Uncertainty of measurement
When measurements of VARIATION are made to verify that an equipment complies with
specified LIMITS OF VARIATION, the OVERALL UNCERTAINTY of these measurements of VARIATION
should be less than one-fifth of the LIMITS OF VARIATION.
If this is not possible and if the OVERALL UNCERTAINTY of the measurement is less than one half
of the LIMITS OF VARIATION OVERALL UNCERTAINTY
, the of the measurement made in the
compliance test procedures shall be taken into account in the evaluation of the equipment
under test by adding the OVERALL UNCERTAINTY to the LIMITS OF VARIATION allowed.
If the OVERALL UNCERTAINTY exceeds one-fifth of the LIMITS OF VARIATION for any PERFORMANCE
CHARACTERISTIC, then this shall be stated.
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 of IEC 60731).
5 Limits of PERFORMANCE CHARACTERISTICS
5.1 RELATIVE INTRINSIC ERROR
&
The RELATIVE INTRINSIC ERROR, I, for AIR KERMA K, AIR KERMA LENGTH K·l and AIR KERMA RATE K
measurements made under STANDARD TEST CONDITIONS (as defined in table 1) shall not exceed
the values given in tables 3 and 4.
Compliance with this performance requirement shall be checked by exposing the RADIATION
DETECTOR in a radiation beam of reproducible geometry and field size. For AIR KERMA LENGTH
measurements the RADIATION DETECTOR shall be positioned with its centre in the central axis of
the beam; the irradiated length, l, of the DETECTOR should correspond to 50 % of the minimum
RATED LENGTH RELATIVE INTRINSIC ERROR
. The shall be measured for one or more points in each
decade over the EFFECTIVE RANGE (i.e. the whole stated measurement range) of AIR KERMA or
AIR KERMA LENGTH and/or AIR KERMA RATE and at the limits of the EFFECTIVE RANGE. If the
DOSIMETER is designed to measure AIR KERMA and AIR KERMA RATE, these measurements shall
be performed in both operating modes.
For AIR KERMA or AIR KERMA LENGTH measurements the average of at least five readings of the
MEASURED VALUE AIR KERMA RATE
instrument shall be taken as the . If the cannot be kept
constant for all measurements over the EFFECTIVE RANGE of AIR KERMA or AIR KERMA LENGTH,
the different AIR KERMA or AIR KERMA LENGTH ranges with different but constant AIR KERMA RATES
shall overlap at their ends for at least one measurement point to obtain CORRECT
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