IEC 60601-2-44:2009
(Main)Medical electrical equipment - Part 2-44: Particular requirements for the basic safety and essential performance of X-ray equipment for computed tomography
Medical electrical equipment - Part 2-44: Particular requirements for the basic safety and essential performance of X-ray equipment for computed tomography
IEC 60601-2-44:2009 applies to the basic safety and essential performance of CT scanners. The scope of IEC 60601-2-44:2009 is limited to CT scanners intended to be used for both head and body characterised by an enclosure of the X-ray source(s) and imaging detector(s) in a common protective cover in the shape of a toroid. It includes safety requirements for the X-ray generators used in CT scanners, including those where high-voltage generators are integrated with an X-ray tube assembly. This third edition cancels and replaces the second edition published in 2001 and its Amendment 1 (2002). This edition constitutes a technical revision primarily related to radiation protection and control. The contents of the corrigendum of May 2010 have been included in this copy.
Appareils électromédicaux - Partie 2-44: Exigences particulières pour la sécurité de base et les performances essentielles des équipements à rayonnement X de tomodensitométrie
La CEI 60601-2-44:2009 s'applique à la sécurité de base et aux performances essentielles des tomodensitomètres. Le domaine d'application de la CEI 60601-2-44:2009 est limité aux tomodensitomètres destinés à être utilisés pour les examens de la tête et du corps caractérisés par une enveloppe de la (des) source(s) de rayonnement X et du (des) détecteur(s) d'imagerie dans un couvercle de protection commun de forme toroïdale. Cette norme comprend les exigences de sécurité des générateurs radiologiques utilisés dans les tomodensitomètres, y compris celles pour les générateurs haute tension lorsqu'ils sont intégrés avec une gaine équipée. Cette troisième édition annule et remplace la deuxième édition parue en 2001 et son Amendement 1 (2002). La présente édition constitue une révision technique qui traite essentiellement de la protection contre les rayonnements et de leur contrôle. Le contenu du corrigendum de mai 2010 a été pris en considération dans cet exemplaire.
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IEC 60601-2-44 ®
Edition 3.0 2009-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Medical electrical equipment –
Part 2-44: Particular requirements for the basic safety and essential performance
of X-ray equipment for computed tomography
Appareils électromédicaux –
Partie 2-44: Exigences particulières pour la sécurité de base et les performances
essentielles des équipements à rayonnement X de tomodensitométrie
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IEC 60601-2-44 ®
Edition 3.0 2009-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Medical electrical equipment –
Part 2-44: Particular requirements for the basic safety and essential
performance of X-ray equipment for computed tomography
Appareils électromédicaux –
Partie 2-44: Exigences particulières pour la sécurité de base et les
performances essentielles des équipements à rayonnement X de
tomodensitométrie
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
X
CODE PRIX
ICS 11.040.50 ISBN 978-2-88910-224-2
– 2 – 60601-2-44 © IEC:2009
CONTENTS
FOREWORD.3
201.1 Scope, object and related standards.5
201.2 Normative references .7
201.3 Terms and definitions .7
201.4 General requirements.12
201.5 General requirements for testing of ME EQUIPMENT.13
201.6 Classification of ME EQUIPMENT and ME SYSTEMS .13
201.7 ME EQUIPMENT identification, marking and documents.14
201.8 Protection against electrical HAZARDS from ME EQUIPMENT.16
201.9 Protection against mechanical HAZARDS of ME EQUIPMENT and ME SYSTEMS .19
201.10 Protection against unwanted and excessive RADIATION HAZARDS .22
201.11 Protection against excessive temperatures and other HAZARDS.22
201.12 Accuracy of controls and instruments and protection against hazardous
outputs .22
201.13 Hazardous situations and fault conditions.23
201.14 PROGRAMMABLE ELECTRICAL MEDICAL SYSTEMS (PEMS) .23
201.15 Construction of ME EQUIPMENT .23
201.16 ME SYSTEMS.23
201.17 ELECTROMAGNETIC COMPATIBILITY of ME EQUIPMENT and ME SYSTEMS.24
203 General requirements for RADIATION protection in diagnostic X-ray equipment .24
Annexes .39
Annex AA (informative) Choosing LOADING FACTORS for tests .39
Annex BB (informative) Estimating CTDI for scan projection RADIOGRAPHY (SPR) .40
vol
Bibliography.41
Index of defined terms used in this particular standard.42
Figure 201.101 – Coordinate system.9
Figure 203.101 – Zone of extra-focal RADIATION .29
Figure 203.102 – Minimum dimensions for STRAY RADIATION measurement.32
Table 203.101 − Test pattern for CTDI .36
free air
60601-2-44 © IEC:2009 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-44: Particular requirements for the basic safety and essential
performance of X-ray equipment for computed tomography
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
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. 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 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
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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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
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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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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 60601-2-44 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
This third edition cancels and replaces the second edition published in 2001 and its
Amendment 1 (2002). This edition constitutes a technical revision primarily related to
RADIATION protection and control.
The text of this particular standard is based on the following documents:
FDIS Report on voting
62B/727/FDIS 62B/734/RVD
Full information on the voting for the approval of this particular standard can be found in the
report on voting indicated in the above table.
– 4 – 60601-2-44 © IEC:2009
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this standard, the following print types are used:
– Requirements and definitions: roman type.
– Test specifications: italic type.
– Informative material appearing outside of tables, such as notes, examples and references: in smaller type.
Normative text of tables is also in a smaller type.
ERMS DEFINED IN CLAUSE 3 OF THE GENERAL STANDARD, IN THIS PARTICULAR STANDARD OR AS
– T
NOTED: SMALL CAPITALS.
In referring to the structure of this standard, the term
– “clause” means one of the seventeen numbered divisions within the table of contents,
inclusive of all subdivisions (e.g. Clause 7 includes subclauses 7.1, 7.2, etc.);
– “subclause” means a numbered subdivision of a clause (e.g. 7.1, 7.2 and 7.2.1 are all
subclauses of Clause 7).
References to clauses within this standard are preceded by the term “Clause” followed by the
clause number. References to subclauses within this particular standard are by number only.
In this standard, the conjunctive “or” is used as an “inclusive or” so a statement is true if any
combination of the conditions is true.
The verbal forms used in this standard conform to usage described in Annex H of the ISO/IEC
Directives, Part 2. For the purposes of this standard, the auxiliary verb:
– “shall” means that compliance with a requirement or a test is mandatory for compliance
with this standard;
– “should” means that compliance with a requirement or a test is recommended but is not
mandatory for compliance with this standard;
– “may” is used to describe a permissible way to achieve compliance with a requirement or
test.
A list of all parts of the IEC 60601 series, published under the general title Medical electrical
equipment, can be found on the IEC website.
The committee has decided that the contents of this particular standard will remain
unchanged until the maintenance result 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.
NOTE The attention of National Committees is drawn to the fact that equipment MANUFACTURERS and testing
organizations may need a transitional period following publication of a new, amended or revised IEC publication in
which to make products in accordance with the new requirements and to equip themselves for conducting new or
revised tests. It is the recommendation of the committee that the content of this publication be adopted for
implementation nationally not earlier than 3 years from the date of publication.
The contents of the corrigendum of May 2010 have been included in this copy.
60601-2-44 © IEC:2009 – 5 –
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-44: Particular requirements for the basic safety and essential
performance of X-ray equipment for computed tomography
201.1 Scope, object and related standards
1)
Clause 1 of the general standard applies, except as follows:
201.1.1 Scope
Replacement:
This International Standard applies to the BASIC SAFETY and ESSENTIAL PERFORMANCE of CT
SCANNERS, hereafter also referred to as ME EQUIPMENT.
If a clause or subclause is specifically intended to be applicable to ME EQUIPMENT only, or to
ME SYSTEMS only, the title and content of that clause or subclause will say so. If that is not the
case, the clause or subclause applies both to ME EQUIPMENT and to ME SYSTEMS, as relevant.
NOTE 1 See also 4.2 of the general standard.
The scope of this document is limited to CT SCANNERS intended to be used for both head and
body characterised by an ENCLOSURE of the X-ray source(s) and imaging detector(s) in a
common protective cover in the shape of a toroid. It includes safety requirements for the X-
RAY GENERATORS used in CT SCANNERS, including those where HIGH-VOLTAGE GENERATORS are
integrated with an X-RAY TUBE ASSEMBLY.
NOTE 2 Requirements for X-RAY GENERATORS and for ASSOCIATED EQUIPMENT, which were previously specified in
IEC 60601-2-7 and IEC 60601-2-32, have been included in either IEC 60601-1:2005 (Ed3) or this edition of
rd
IEC 60601-2-44. Therefore IEC 60601-2-7 and IEC 60601-2-32 are not part of the 3 edition scheme for COMPUTED
TOMOGRAPHY.
201.1.2 Object
Replacement:
The object of this particular standard is to establish particular BASIC SAFETY and ESSENTIAL
PERFORMANCE requirements for CT SCANNERS as defined in 201.3.201, to ensure safety, and to
specify methods for demonstrating compliance with those requirements, for CT SCANNERS.
NOTE 1 Requirements for reproducibility, linearity, constancy and accuracy are given because of their
relationship to the quality and quantity of the IONIZING RADIATION produced and are confined to those considered
necessary for safety.
NOTE 2 Both the levels for compliance and the tests prescribed to determine compliance reflect the fact that the
safety of HIGH-VOLTAGE GENERATORS is not sensitive to small differences in levels of performance. The
combinations of LOADING FACTORS specified for the tests are therefore limited in number but chosen from
experience as being appropriate in most cases. It is considered important to standardize the choice of
combinations of LOADING FACTORS so that comparison can be made between tests performed in different places on
different occasions. However, combinations other than those specified could be of equal technical validity.
NOTE 3 The safety philosophy on which this standard is based is described in the introduction to the general
standard and in IEC TR 60513.
—————————
1)
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic safety and essential
performance.
– 6 – 60601-2-44 © IEC:2009
NOTE 4 Concerning RADIOLOGICAL PROTECTION, it is assumed that MANUFACTURERS and RESPONSIBILE
ORGANIZATIONS accept the general principles of justification, optimisation, and application of dose limits of the
2)
International Commission on Radiological Protection as stated in ICRP 103, 2007, paragraph 203, [ 12] namely:
(a) “The principle of justification: Any decision that alters the RADIATION exposure situation should do more good
than harm.”
(b) “The principle of optimisation of protection: The likelihood of incurring exposures, the number of people
exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable, taking
into account economic and societal factors.”
(c) “The principle of application of dose limits: The total dose to any individual from regulated sources in planned
exposure situations other than medical exposure of PATIENTS should not exceed the appropriate limits
recommended by the Commission.”
(d) "Application of dose limits for the PATIENT dose might be to the PATIENT’S detriment. Therefore dose limits
should not be applied to medical exposures. However, considerations should be given to the use of dose
constraints or investigation levels for some common diagnostic procedures. This concept, now renamed as
diagnostic reference levels, has been introduced in a large number of countries."
NOTE 5 It is recognized that many of the judgements necessary to follow the ICRP general principles have to be
made by the RESPONSIBLE ORGANIZATIONS and not by the MANUFACTURER of the ME EQUIPMENT.
201.1.3 Collateral standards
Addition:
This particular standard refers to those applicable collateral standards that are listed in
Clause 2 of the general standard and Clause 201.2 of this particular standard.
IEC 60601-1-3 applies as modified in Clause 203. IEC 60601-1-8, IEC 60601-1-9 and
3)
IEC 60601-1-10 do not apply. All other published collateral standards in the IEC 60601-1
series apply as published.
201.1.4 Particular standards
Replacement:
In the IEC 60601 series, particular standards may modify, replace or delete requirements
contained in the general standard and collateral standards as appropriate for the particular
ME EQUIPMENT under consideration, and may add other BASIC SAFETY and ESSENTIAL
PERFORMANCE requirements.
A requirement of a particular standard takes priority over the general standard.
For brevity, IEC 60601-1 is referred to in this particular standard as the general standard.
Collateral standards are referred to by their document numbers.
The numbering of clauses and subclauses of this particular standard corresponds to that of
the general standard with the prefix “201” (e.g. 201.1 in this standard addresses the content
of Clause 1 of the general standard) or applicable collateral standard with the prefix “20x”
where x is the final digit(s) of the collateral standard document number (e.g. 202.4 in this
particular standard addresses the content of Clause 4 of the 60601-1-2 collateral standard,
203.4 in this particular standard addresses the content of Clause 4 of the 60601-1-3 collateral
standard, etc.). The changes to the text of the general standard are specified by the use of
the following words:
—————————
2)
Figures in square brackets refer to the Bibliography.
3)
IEC 60601-1-10, Medical electrical equipment – Part 1-10: General requirements for basic safety and essential
performance – Collateral Standard: Requirements for the development of physiologic closed-loop controllers
60601-2-44 © IEC:2009 – 7 –
"Replacement" means that the clause or subclause of the general standard or applicable
collateral standard is replaced completely by the text of this particular standard.
"Addition" means that the text of this particular standard is additional to the requirements of
the general standard or applicable collateral standard.
"Amendment" means that the clause or subclause of the general standard or applicable
collateral standard is amended as indicated by the text of this particular standard.
Subclauses, figures or tables which are additional to those of the general standard are
numbered starting from 201.101. However, due to the fact that definitions in the general
standard are numbered 3.1 through 3.139, additional definitions in this standard are
numbered beginning from 201.3.201. Additional annexes are lettered AA, BB, etc., and
additional items aa), bb), etc.
Subclauses, figures or tables which are additional to those of a collateral standard are
numbered starting from 20x, where “x” is the number of the collateral standard, e.g. 202 for
IEC 60601-1-2, 203 for IEC 60601-1-3, etc.
The term "this standard" is used to make reference to the general standard, any applicable
collateral standards and this particular standard taken together.
Where there is no corresponding section, clause or subclause in this particular standard, the
section, clause or subclause of the general standard or applicable collateral standard,
although possibly not relevant, applies without modification; where it is intended that any
parts of the general standard or applicable collateral standard, although possibly relevant, is
not to be applied, a statement to that effect is given in this particular standard.
201.2 Normative references
NOTE Informative references are listed in the bibliography beginning on page 41.
Clause 2 of the general standard applies, except as follows:
Replacement:
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
Addition:
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic
safety and essential performance
IEC 61223-3-5, Evaluation and routine testing in medical imaging departments – Part 3-5:
Acceptance tests – Imaging performance of computed tomography X-ray equipment
ISO 12052, Health informatics – Digital imaging and communication in medicine (DICOM)
including workflow and data management
201.3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60601-1:2005, IEC
60601-1-3:2008 and IEC 60788:2004 apply, except as follows:
– 8 – 60601-2-44 © IEC:2009
NOTE 101 An index of defined terms is to be found at the end of this document.
NOTE 102 In accordance with the definitions in IEC 60601-1-3, in this standard unless otherwise indicated:
– values of X-RAY TUBE VOLTAGE refer to peak values, transients being disregarded;
– values of X-RAY TUBE CURRENT refer to average values.
Addition:
201.3.201
CT SCANNER
X-RAY EQUIPMENT intended to generate cross-sectional images of the body by computer
reconstruction of X-ray transmission data obtained at different angles, which may include
signal analysis and display equipment, PATIENT SUPPORT, support parts and ACCESSORIES
NOTE 1 The scope of this document is limited to CT SCANNERS intended to be used for both head and body
characterised by an ENCLOSURE of the X-ray source(s) and imaging detector(s) in a common protective cover in the
shape of a toroid.
NOTE 2 Secondary imaging processing is not included in the scope of this standard.
201.3.202
CT CONDITIONS OF OPERATION
all selectable parameters governing the operation of a CT SCANNER
NOTE 1 Examples of such conditions include NOMINAL TOMOGRAPHIC SECTION THICKNESS, CT PITCH FACTOR,
FILTRATION, peak X-RAY TUBE VOLTAGE and either X-RAY TUBE CURRENT and LOADING TIME or CURRENT TIME PRODUCT.
NOTE 2 Some CT CONDITIONS OF OPERATION may vary during the exposure.
201.3.203
COMPUTED TOMOGRAPHY DOSE INDEX 100
CTDI
integral of the DOSE PROFILE produced in a single axial scan along a line perpendicular to
the TOMOGRAPHIC PLANE from –50 mm to +50 mm, divided by the product of the number of
TOMOGRAPHIC SECTIONS N and the NOMINAL TOMOGRAPHIC SECTION THICKNESS T, or divided by
100 mm, whichever is less:
+50 mm
D (z)
= dz
CTDI100
∫
min{N × T,100 mm}
−50 mm
where
D(z) is the DOSE PROFILE along a line z perpendicular to the TOMOGRAPHIC PLANE, where
dose is reported as ABSORBED DOSE in air and is evaluated within a
polymethylmethacrylate (PMMA) dosimetry PHANTOM (203.108);
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-ray
source;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS.
NOTE 1 The dose is reported as ABSORBED DOSE in air. Air is explicitly designated the reference medium for dose
in order to avoid potential confusion, since some MANUFACTURERS of CT SCANNERS express dose values calculated
as ABSORBED DOSE to air and others as ABSORBED DOSE to PMMA.
Although CTDI refers to ABSORBED DOSE in air, for practical purposes the evaluation of ABSORBED DOSE to air
within a PMMA dosimetry PHANTOM is well approximated by measurement of the AIR KERMA with an ionization
chamber in the PHANTOM. Generally there is traceability of ionization chambers to AIR KERMA.
NOTE 2 This definition assumes that the DOSE PROFILE is centred on z = 0.
NOTE 3 A single axial scan is typically a 360° rotation of the X-ray source.
NOTE 4 When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with “flying FOCAL SPOT”, the product
N × T needs to be adjusted for overlap.
60601-2-44 © IEC:2009 – 9 –
NOTE 5 Typically the z-axis is the axis of rotation.
NOTE 6 If N × T is greater than 100 mm, the physical meaning of CTDI changes from the average dose at the
centre of a 100 mm scan length to the average dose over the central 100 mm region for a single axial scan.
NOTE 7 The value of CTDI will be lower if the length of the dosimetry PHANTOM is less than N × T + 100 mm,
since the contribution from scattered RADIATION will be underestimated.
y
T
x
z
IEC 369/09
1 TOMOGRAPHIC PLANE
2 PHANTOM
Figure 201.101 – Coordinate system
201.3.204
CT PITCH FACTOR
in helical scanning the ratio of the PATIENT SUPPORT travel Δd along the z-direction per rotation
of the X-ray source divided by the product of the NOMINAL TOMOGRAPHIC SECTION THICKNESS T
and the number of TOMOGRAPHIC SECTIONS N:
Δd
CT pitch factor =
N ×T
where
Δd is the PATIENT SUPPORT travel along the z-direction per rotation of the X-RAY SOURCE;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS;
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-RAY
SOURCE.
NOTE 1 Although the CT PITCH FACTOR is associated with helical scanning, its definition refers to parameters T
and N that are defined only for axial scanning. Definition 201.3.204 presumes that these axial-scanning parameters
T and N correspond to the same collimation and active-detector configuration as that of the helical scanning for
which the CT PITCH FACTOR is being evaluated.
NOTE 2 When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with “flying FOCAL SPOT”, the product
N × T needs to be adjusted for overlap.
NOTE 3 CT PITCH FACTOR will be a function of time when Δd or N × T are variable during the exposure.
NOTE 4 The terms “helical” is used in this document as a synonym for the term “spiral”.
201.3.205
DOSE PROFILE
representation of the dose as a function of position along a line
– 10 – 60601-2-44 © IEC:2009
201.3.206
NOMINAL TOMOGRAPHIC SECTION THICKNESS
in CT SCANNERS the TOMOGRAPHIC SECTION THICKNESS which is selected and indicated on the
CONTROL PANEL
NOTE In helical scanning the thickness of a section associated with the reconstructed image depends on the
helical reconstruction algorithm and pitch. This thickness might or might not be equal to the NOMINAL TOMOGRAPHIC
SECTION THICKNESS.
201.3.207
SENSITIVITY PROFILE
relative response of a system for COMPUTED TOMOGRAPHY as a function of position along a line
perpendicular to the TOMOGRAPHIC PLANE
201.3.208
TOMOGRAPHIC PLANE
geometric plane perpendicular to the axis of rotation at the centre of the X-RAY FIELD in z (see
Figure 201.101)
201.3.209
TOMOGRAPHIC SECTION
for CT SCANNERS with a single detector row, the volume over which TRANSMISSION data of
X-RADIATION are collected in a single axial scan; for CT SCANNERS with multiple detector rows
along the z-axis, the volume over which data are collected by a single acquisition channel
representing a single row or a selected grouping of rows
201.3.210
TOMOGRAPHIC SECTION THICKNESS
FULL WIDTH AT HALF MAXIMUM of the SENSITIVITY PROFILE taken at the ISOCENTRE of a
TOMOGRAPHIC SECTION
201.3.211
WEIGHTED CTDI
CTDI
w
value defined as
1 2
CTDI = CTDI + CTDI
W 100(centre ) 100(peripheral)
3 3
where CTDI is the value of CTDI measured in the centre of a dosimetry PHANTOM,
100(centre) 100
and where CTDI is the average of the four values of CTDI measured around
100(peripheral) 100
the dosimetry PHANTOM periphery according to 203.109.1 a)2) and 3)
201.3.212
VOLUME CTDI
w
CTDI
vol
a) for axial scanning
N ×T
CTDI = CTDI
vol w
Δd
where
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-
ray source;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS;
Δd is the PATIENT SUPPORT travel in z-direction between consecutive scans.
NOTE 1 For axial scanning with a total table travel of less than N × T this definition may overestimate the dose.
60601-2-44 © IEC:2009 – 11 –
NOTE 2 For the selected CT CONDTIONS OF OPERATION, but irrespective of any scanning length that may be used
clinically, the VOLUME CTDI (CTDI ) is an index of dose based on a convention of 100 mm range of integration
w vol
along the z-axis. For axial scanning, CTDI corresponds to the average dose that would accrue in the PHANTOM
vol
central section of volume equal to the cross sectional area × Δd .
b) for helical scanning
CTDI
w
CTDI =
vol
CT pitch factor
NOTE 1 CT PITCH FACTOR will be a function of time when Δd or N × T are variable during the exposure.
NOTE 2 For helical scanning with a small number of rotations and a table travel per rotation of less than N × T
this definition may overestimate the dose.
NOTE 3 For the selected CT CONDTIONS OF OPERATION, but irrespective of any scanning length that may be used
clinically, the VOLUME CTDI (CTDI ) is an index of dose based on a convention of 100 mm range of integration
w vol
along the z-axis. For helical scanning, CTDI corresponds to the average dose that would accrue in the PHANTOM
vol
central section of volume equal to the cross sectional area × Δd.
c) for scanning without movement of the PATIENT SUPPORT
CTDI = n × CTDI
vol w
where n is equal to the number of rotations.
NOTE 1 c) includes situations where the PATIENT SUPPORT may be moved manually, for example, during an
interventional procedure.
NOTE 2 For scanning without movement of the PATIENT SUPPORT and for situations where the PATIENT SUPPORT
may be moved manually, this definition overestimates the dose as it includes assumed scatter contribution from
adjacent slices.
NOTE 3 For scanning without movement of the PATIENT SUPPORT, CTDI corresponds to the dose that would
vol
accrue in the PHANTOM central section of volume equal to the cross sectional area × N × T were there n congruent
sequences of contiguous scanning, each sequence of length 100 mm.
201.3.213
GEOMETRIC EFFICIENCY IN THE Z-DIRECTION
integral of the DOSE PROFILE determined at the ISOCENTRE without any object in the X-RAY BEAM,
over the acquisition range in the z-direction, expressed as percentage of the total integral of the
DOSE PROFILE in the z-direction, where the acquisition range is the length along the z-axis
spanned by the selected detector elements, or it is the z-axis length of the post-patient collimation,
whichever is less and where z-axis lengths are given as equivalent lengths at the ISOCENTRE
NOTE Detector ‘combs’ or grids will reduce geometric efficiency.
201.3.214
DOSE-LENGTH PRODUCT
DLP
index characterizing the product of the CTDI and the total length scanned
vol
a) For axial scanning
DLP = CTDI × Δd × n
vol
where
Δd is the PATIENT SUPPORT travel in z-direction between consecutive scans;
n is the number of scans in the series.
b) For helical scanning
DLP = CTDI × L
vol
where
L is the table travel during the entire LOADING.
– 12 – 60601-2-44 © IEC:2009
NOTE 1 L might be longer than the programmed scan length.
NOTE 2 The time weighted average of CTDI is to be used if CTDI is variable.
vol vol
c) For scanning without movement of the PATIENT SUPPORT
DLP = CTDI × N × T
vol
where
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-ray
source;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS.
201.3.215
COMPUTED TOMOGRAPHY DOSE INDEX FREE-IN-AIR
CTDI
FREE AIR
integral of the DOSE PROFILE produced in a single axial scan along a line perpendicular to
the TOMOGRAPHIC PLANE from –50 mm to +50 mm, divided by the product of the number of
TOMOGRAPHIC SECTIONS N and the NOMINAL TOMOGRAPHIC SECTION THICKNESS T, or divided by
100 mm, whichever is less
+50 mm
D (z)
= dz
CTDI FREE AIR
∫
min{N × T,100 mm}
−50 mm
where
D(z) is the DOSE PROFILE along a line z perpendicular to the TOMOGRAPHIC PLANE, where
dose is reported as ABSORBED DOSE in air and is evaluated free-in-air in the absence
of a PHANTOM and the PATIENT SUPPORT;
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-ray
source;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS.
NOTE 1 This definition assumes that the DOSE PROFILE is centred on z = 0.
201.4 General requirements
Clause 4 of the general standard applies, except as follows:
201.4.3 ESSENTIAL PERFORMANCE
Addition:
For CT SCANNERS for which the INTENDED USE includes COMPUTED TOMOGRAPHY as the
principal means of guidance in invasive procedures (involving the introduction of a device,
such as a needle or a catheter into the body of the PATIENT), any ESSENTIAL PERFORMANCE
related to such use shall be identified.
Compliance is checked by inspection of the RISK MANAGEMENT FILE.
201.4.5 Equivalent Safety for ME EQUIPMENT or ME SYSTEMS
Addition:
NOTE Because state of the art technology changes for CT SCANNERS may result in the inability to strictly comply
with all clauses of this particular standard, alternate means of addressing risks via risk management are acceptable.
Alternate means are acceptable only when the residual risks resulting from application of the alternative are equal
to or less than the RESIDUAL RISKS that would ensue when the particular standards requirements are met.
60601-2-44 © IEC:2009 – 13 –
201.4.10.2 SUPPLY MAINS for ME EQUIPMENT and ME SYSTEMS
Addition:
The internal impedance of a SUPPLY MAINS is to be considered sufficiently low for the operation
of a CT SCANNER if the value of the APPARENT RESISTANCE OF SUPPLY MAINS does not exceed
the value specified in the ACCOMPANYING DOCUMENTS.
Either the APPARENT RESISTANCE OF SUPPLY MAINS or the proper gauge/length of supply cables
or other appropriate SUPPLY MAINS specifications used in a facility shall be specified in the
ACCOMPANYING DOCUMENTS.
NOTE If a NOMINAL voltage is claimed for a mains power supply system, it is assumed that there is no voltage of a
higher value between any of the conductors of the system or between any of these conductors and earth.
An alternating voltage is considered in practice to be sinusoidal if any instantaneous value of the waveform
concerned differs from the instantaneous value of the ideal waveform at the same moment by no more than ±2 % of
the peak value of the ideal waveform.
SUPPLY MAINS is considered to have a practical symmetry if it delivers symmetrical voltages and
A three-phase
produces, when loaded symmetrically, symmetrical currents.
The requirements of this standard are based upon the assumption that three-phase systems have a symmetrical
configuration of the MAINS VOLTAGE with respect to earth. Single-phase systems may be derived from such
three-phase systems. Where the supply system is not earthed at the source it is assumed that adequate measures
have been provided to detect, limit and remedy any disturbance of symmetry within a reasonably short time.
A CT SCANNER is considered to comply with the requirements of this standard only if its specified NOMINAL ELECTRIC
POWER can be demonstrated at an APPARENT RESISTANCE OF SUPPLY MAINS having a value not less than the
APPARENT RESISTANCE OF SUPPLY MAINS specified by the MANUFACTURER in the ACCOMPANYING DOCUMENTS.
Compliance is checked by inspection of the ACCOMPANYING DOCUMENTS.
201.5 General requirements for testing of ME EQUIPMENT
Clause 5 of the general standard applies, except as follows:
201.5.7 Humidity preconditioning treatment
Addition:
For those CT SCANNERS that are to be used only in controlled environments, as to be specified
in the ACCOMPANYING DOCUMENTS, no humidity preconditioning is required.
The ACCOMPANYING DOCUMENTS shall include the time period that the room environmental
operating conditions must be maintained prior to powering the system on.
Compliance is checked by inspection of the ACCOMPANYING DOCUMENTS.
201.6 Classification of ME EQUIPMENT and ME SYSTEMS
Clause 6 of the general standard applies, except as follows:
201.6.2 Protection against electric shock
Replacement:
HIGH-VOLTAGE GENERATORS in CT SCANNERS shall be CLASS I ME EQUIPMENT or INTERNALLY
POWERED ME EQUIPMENT.
– 14 – 60601-2-44 © IEC:2009
201.6.6 MODE OF OPERATION
Replacement:
Unless otherwise specified, CT SCANNERS or sub-assemblies thereof shall be classified as
suitable for continuous connection to the SUPPLY MAINS in the STAND-BY STATE and for
specified LOADINGS.
201.7 ME EQUIPMENT identification, marking and documents
Clause 7 of the general standard applies, except as follows:
201.7.2.15 Cooling conditions
Addition:
The cooling requirements for the safe operation of a CT SCANNER, or a sub-assembly thereof,
shall be indicated in the ACCOMPANYING DOCUMENTS, including as appropriate the maximum
heat dissipation.
201.7.8.1 Colours of indicator lights
Addition after the first paragraph:
For CT SCANNERS, the colours to be used for indicator lights shall be as follows:
– the colour green shall be used at the CONTROL PANEL to indicate the state from which one
further action leads to the LOADING STATE; see 203.103;
– the colour yellow shall be used at the CONTROL PANEL to indicate the LOADING STATE; see
203.6.4.2.
NOTE 101 The colours of indicator lights need to be chosen according to the message to be given. Thus, the
same operational state of an X-RAY EQUIPMENT can have simultaneous indications in different colours depending
upon the place of indication, for example green at the CONTROL PANEL and red at the entrance to the examination
room.
201.7.9 ACCOMPANYING DOCUMENTS
201.7.9.2.2 Warning and safety notices
Addition:
For risks not sufficiently mitigated in 201.9.2, warnings shall be given in the ACCOMPANYING
DOCUMENTS, or markings provided on the equipment to mitigate the RISK of injuries that could
result from collision of power driven equipment parts with other moving or stationary items
likely to be in the environment.
201.7.9.2.9 Operating instructions
Addition:
Electric output data shall be stated in the instructions for use in terms of LOADING FACTORS as
required in 201.12.1.103.
For CT SCANNERS in which part of the HIGH-VOLTAGE GENERATOR is integrated with the X-RAY
TUBE ASSEMBLY (for example X-RAY TUBE HEADS) the stated values shall refer to the complete
device.
60601-2-44 © IEC:2009 – 15 –
The following combinations and data shall be stated:
1) the corresponding NOMINAL X-RAY TUBE VOLTAGE together with the highest X-RAY TUBE
CURRENT obtainable from the HIGH-VOLTAGE GENERATOR when operated at that X-RAY TUBE
VOLTAGE;
2) the corresponding highest X-RAY TUBE CURRENT together with the highest X-RAY TUBE
VOLTAGE, obtainable from the HIGH-VOLTAGE GENERATOR when operating at that X-RAY TUBE
CURRENT;
3) the corresponding combination of X-RAY TUBE VOLTAGE and X-RAY TUBE CURRENT which
results in the highest electric output power;
4) the NOMINAL ELECTRIC POWER given as the highest constant electric output power in
kilowatts which the HIGH-VOLTAGE GENERATOR can deliver, for a LOADING TIME of 4 s at an
X-RAY TUBE VOLTAGE of 120 kV, or if these values are not selectable, with an X-RAY TUBE
VOLTAGE nearest to 120 kV and the value of LOADING TIME nearest to but not less than 4 s.
The NOMINAL ELECTRIC POWER shall be given together with the combination of X-RAY TUBE
VOLTAGE and X-RAY TUBE CURRENT and the LOADING TIME which are used in the CT SCANNER.
201.7.9.3 Technical description
201.7.9.3.1 General
Addition:
The technical description shall contain information about the combination or, if necessary, the
combinations of sub-assemblies and ACCESSORIES of a CT SCANNER.
Additional subclause:
201.7.9.101 Reference to ACCOMPANYING DOCUMENTS
Clauses and subclauses of this standard, in which additional requirements concerning the
content of ACCOMPANYING DOCUMENTS are given:
– APPARENT RESISTA
...
IEC 60601-2-44 ®
Edition 3.2 2016-03
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Medical electrical equipment –
Part 2-44: Particular requirements for the basic safety and essential performance
of X-ray equipment for computed tomography
Appareils électromédicaux –
Partie 2-44: Exigences particulières pour la sécurité de base et les performances
essentielles des équipements à rayonnement X de tomodensitométrie
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IEC 60601-2-44 ®
Edition 3.2 2016-03
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Medical electrical equipment –
Part 2-44: Particular requirements for the basic safety and essential
performance of X-ray equipment for computed tomography
Appareils électromédicaux –
Partie 2-44: Exigences particulières pour la sécurité de base et les
performances essentielles des équipements à rayonnement X de
tomodensitométrie
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 11.040.50 ISBN 978-2-8322-3290-3
IEC 60601-2-44 ®
Edition 3.2 2016-03
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Medical electrical equipment –
Part 2-44: Particular requirements for the basic safety and essential performance
of X-ray equipment for computed tomography
Appareils électromédicaux –
Partie 2-44: Exigences particulières pour la sécurité de base et les performances
essentielles des équipements à rayonnement X de tomodensitométrie
– 2 – IEC 60601-2-44:2009+AMD1:2012
+AMD2:2016 CSV IEC 2016
CONTENTS
FOREWORD. 4
Introduction to Amendment 1 . 7
Introduction to Amendment 2 . 8
201.1 Scope, object and related standards . 9
201.2 Normative references . 11
201.3 Terms and definitions . 12
201.4 General requirements . 20
201.5 General requirements for testing of ME EQUIPMENT . 21
201.6 Classification of ME EQUIPMENT and ME SYSTEMS . 21
201.7 ME EQUIPMENT identification, marking and documents . 22
201.8 Protection against electrical HAZARDS from ME EQUIPMENT . 24
201.9 Protection against mechanical HAZARDS of ME EQUIPMENT and ME SYSTEMS . 27
201.10 Protection against unwanted and excessive RADIATION HAZARDS . 30
201.11 Protection against excessive temperatures and other HAZARDS . 31
201.12 Accuracy of controls and instruments and protection against hazardous
outputs . 31
201.13 Hazardous situations and fault conditions . 32
201.14 PROGRAMMABLE ELECTRICAL MEDICAL SYSTEMS (PEMS) . 32
201.15 Construction of ME EQUIPMENT . 32
201.16 ME SYSTEMS . 32
201.17 ELECTROMAGNETIC COMPATIBILITY of ME EQUIPMENT and ME SYSTEMS . 32
201.101 Requirements for CT SCANNERS providing images for RADIOTHERAPY
TREATMENT PLANNING (RTP) . 32
202 Electromagnetic compatibility – Requirements and tests . 38
203 General requirements for RADIATION protection in diagnostic X-ray equipment . 38
Annexes . 56
Annex AA (informative) Choosing LOADING FACTORS for tests . 56
)
Annex BB (informative) Estimating CTDI for scan projection RADIOGRAPHY (SPR) . 57
vol
Annex CC (informative) The CTDI concept in IEC 60601-2-44: Relationship
between CTDI and CTDI . 58
100 ∞
Annex DD (informative) Measuring CTDI . 62
free air
Bibliography . 64
Index of defined terms used in this particular standard . 66
Figure 201.101 – Coordinate system . 14
Figure 201.102 – Illustration of N × T, R and (N × T) + R. 17
Figure 201.103 – Vertical alignment of the PATIENT SUPPORT . 33
Figure 201.104 – Z-axis alignment of the PATIENT SUPPORT in the horizontal plane . 35
Figure 203.101 – Zone of extra-focal RADIATION . 44
Figure 203.102 – Minimum dimensions for STRAY RADIATION measurement . 47
Figure CC.1 – CTDI versus beam width along z . 59
w
+AMD2:2016 CSV IEC 2016
Table 203.101 − Test pattern for CTDIfree air . 52
Table CC.1 – Ratios of CTDI by phantom length . 61
– 4 – IEC 60601-2-44:2009+AMD1:2012
+AMD2:2016 CSV IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-44: Particular requirements for the basic safety and essential
performance of X-ray equipment for computed tomography
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
This consolidated version of the official IEC Standard and its amendments has been prepared
for user convenience.
IEC 60601-2-44 edition 3.2 contains the third edition (2009-02) [documents 62B/727/FDIS and
62B/734/RVD] and its corrigendum (May 2010), its amendment 1 (2012-08) [documents 62B/879/
FDIS and 62B/890/RVD] and its amendment 2 (2016-03) [documents 62B/976/CDV and 62B/994/
CDV].
In this Redline version, a vertical line in the margin shows where the technical content is
modified by amendments 1 and 2. Additions are in green text, deletions are in strikethrough
red text. A separate Final version with all changes accepted is available in this publication.
+AMD2:2016 CSV IEC 2016
International standard IEC 60601-2-44 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this standard, the following print types are used:
– Requirements and definitions: roman type.
– Test specifications: italic type.
– Informative material appearing outside of tables, such as notes, examples and references: in smaller type.
Normative text of tables is also in a smaller type.
– TERMS DEFINED IN CLAUSE 3 OF THE GENERAL STANDARD, IN THIS PARTICULAR STANDARD OR AS
NOTED: SMALL CAPITALS.
In referring to the structure of this standard, the term
– “clause” means one of the seventeen numbered divisions within the table of contents,
inclusive of all subdivisions (e.g. Clause 7 includes subclauses 7.1, 7.2, etc.);
– “subclause” means a numbered subdivision of a clause (e.g. 7.1, 7.2 and 7.2.1 are all
subclauses of Clause 7).
References to clauses within this standard are preceded by the term “Clause” followed by the
clause number. References to subclauses within this particular standard are by number only.
In this standard, the conjunctive “or” is used as an “inclusive or” so a statement is true if any
combination of the conditions is true.
The verbal forms used in this standard conform to usage described in Annex H of the ISO/IEC
Directives, Part 2. For the purposes of this standard, the auxiliary verb:
– “shall” means that compliance with a requirement or a test is mandatory for compliance
with this standard;
– “should” means that compliance with a requirement or a test is recommended but is not
mandatory for compliance with this standard;
– “may” is used to describe a permissible way to achieve compliance with a requirement or test.
A list of all parts of the IEC 60601 series, published under the general title Medical electrical
equipment, can be found on the IEC website.
– 6 – IEC 60601-2-44:2009+AMD1:2012
+AMD2:2016 CSV IEC 2016
The committee has decided that the contents of the base publication and its amendments 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.
NOTE The attention of National Committees is drawn to the fact that equipment MANUFACTURERS and testing
organizations may need a transitional period following publication of a new, amended or revised IEC publication in
which to make products in accordance with the new requirements and to equip themselves for conducting new or
revised tests. It is the recommendation of the committee that the content of this publication be adopted for
implementation nationally not earlier than 3 years from the date of publication.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
+AMD2:2016 CSV IEC 2016
Introduction to Amendment 1
The main topic addressed in this amendment is an extended concept of CTDI to
accommodate CT SCANNERS with very large z-coverage. The other principal subject areas
include:
1) a dose-check feature associated with a pre-scanning alert if expected values of dose
indices exceed user-configurable DOSE NOTIFICATION VALUES or DOSE ALERT VALUES and
2) requirements covering the use of CT data in radiotherapy treatment planning (RTP).
The CT dose metric in use has been based on the CTDI , i.e. measurement of dose in
PHANTOMs and limited integration of scattered radiation, and it is used in many countries’
legislation to define "dose reference values" (also called "diagnostic reference levels") for CT
examinations. Many people use these indices, CTDI and DLP, to derive estimates for
vol
effective dose via conversion factors. CTDI is also part of CT acceptance and constancy
testing. The introduction of a new dose index would change all CT SCANNERS’ CTDI values.
Therefore the intention is to stay with the CTDI , i.e. the integration of primary radiation and
scatter over 100 mm, but adapt the way of measuring and reporting the dose index to
incorporate large collimations and to rate all collimations the same way, i.e. to reflect
approximately the same percentage of CTDI for all collimations.
∞
As defined in the amendment, CTDI is to be measured only for collimations up to 40 mm
with the current equipment, i.e. the PMMA PHANTOMs and a 100-mm chamber, or other
suitable methods that use a RADIATION DETECTOR. For these collimations there is no significant
change of the ratio CTDI / CTDI according to published data. For larger collimations at
100 ∞
the same CT CONDITIONS OF OPERATION, the z-efficiency may be different and must be
evaluated in the dose measurement. This can be accomplished by the measurement of dose
‘free air’. Based on these considerations CTDI and the CTDI have been refined. Both
100 free air
types of measurement are combined now to determine the CTDI values for larger collimations
and they are explained in detail in informative Annexes CC and DD.
Some additional requirements and refinements related to dose have been added: CTDI and
vol
DLP are defined for a new type of scan mode (‘shuttle mode’). In body CT EXAMINATION it is
clarified that the CTDI and DLP always be reported for the 32-cm diameter PHANTOM. In the
vol
amendment it is now required that CT SCANNERS support user-configurable DOSE NOTIFICATION
VALUES and DOSE ALERT VALUES.
A new subject area in this Amendment 1 covers requirements for CT SCANNERS providing
images for radiotherapy treatment planning. With this amendment begins the implementation
of this important CT application into the CT safety standard with a set of requirements that is
considered to be safety relevant. It mainly covers scanner hardware adjustments, accuracy of
CT image data, and the conversion of HU to electron and mass density.
– 8 – IEC 60601-2-44:2009+AMD1:2012
+AMD2:2016 CSV IEC 2016
Introduction to Amendment 2
The main topics addressed in this amendment are editorial corrections and implementation of
the last publications of the general and collateral standards as normative references.
Given the degree and significance of the changes to the normative references cited in this
amendment, the committee has determined that a 4 year transition period is warranted and
appropriate.
+AMD2:2016 CSV IEC 2016
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-44: Particular requirements for the basic safety and essential
performance of X-ray equipment for computed tomography
201.1 Scope, object and related standards
1)
Clause 1 of the general standard applies, except as follows:
201.1.1 Scope
Replacement:
This International Standard applies to the BASIC SAFETY and ESSENTIAL PERFORMANCE of CT
SCANNERS, hereafter also referred to as ME EQUIPMENT.
If a clause or subclause is specifically intended to be applicable to ME EQUIPMENT only, or to
ME SYSTEMS only, the title and content of that clause or subclause will say so. If that is not the
case, the clause or subclause applies both to ME EQUIPMENT and to ME SYSTEMS, as relevant.
NOTE 1 See also 4.2 of the general standard.
The scope of this document is limited to CT SCANNERS intended to be used for both head and
body characterised by an ENCLOSURE of the X-ray source(s) and imaging detector(s) in a
common protective cover in the shape of a toroid. It includes safety requirements for the X-
RAY GENERATORS used in CT SCANNERS, including those where HIGH-VOLTAGE GENERATORS are
integrated with an X-RAY TUBE ASSEMBLY.
NOTE 2 Requirements for X-RAY GENERATORS and for ASSOCIATED EQUIPMENT, which were previously specified in
IEC 60601-2-7 and IEC 60601-2-32, have been included in either IEC 60601-1:2005 (Ed3) or this edition of
rd
IEC 60601-2-44. Therefore IEC 60601-2-7 and IEC 60601-2-32 are not part of the 3 edition scheme for COMPUTED
TOMOGRAPHY.
The scope of this International Standard excludes RADIOTHERAPY SIMULATORS and systems
where the image is created by a source other than an X-RAY TUBE.
201.1.2 Object
Replacement:
The object of this particular standard is to establish particular BASIC SAFETY and ESSENTIAL
PERFORMANCE requirements for CT SCANNERS as defined in 201.3.201, to ensure safety, and to
specify methods for demonstrating compliance with those requirements, for CT SCANNERS.
NOTE 1 Requirements for reproducibility, linearity, constancy and accuracy are given because of their
relationship to the quality and quantity of the IONIZING RADIATION produced and are confined to those considered
necessary for safety.
NOTE 2 Both the levels for compliance and the tests prescribed to determine compliance reflect the fact that the
safety of HIGH-VOLTAGE GENERATORS is not sensitive to small differences in levels of performance. The
combinations of LOADING FACTORS specified for the tests are therefore limited in number but chosen from
experience as being appropriate in most cases. It is considered important to standardize the choice of
combinations of LOADING FACTORS so that comparison can be made between tests performed in different places on
different occasions. However, combinations other than those specified could be of equal technical validity.
—————————
1)
The general standard is IEC 60601-1:2005 and IEC 60601-1:2005/AMD1:2012, Medical electrical equipment –
Part 1: General requirements for basic safety and essential performance.
– 10 – IEC 60601-2-44:2009+AMD1:2012
+AMD2:2016 CSV IEC 2016
NOTE 3 The safety philosophy on which this standard is based is described in the introduction to the general
standard and in IEC TR 60513.
NOTE 4 Concerning RADIOLOGICAL PROTECTION, it is assumed that MANUFACTURERS and RESPONSIBILE
ORGANIZATIONS accept the general principles of justification, optimisation, and application of dose limits of the
2)
International Commission on Radiological Protection as stated in ICRP 103, 2007, paragraph 203, [12] namely:
(a) “The principle of justification: Any decision that alters the RADIATION exposure situation should do more good
than harm.”
(b) “The principle of optimisation of protection: The likelihood of incurring exposures, the number of people
exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable, taking
into account economic and societal factors.”
(c) “The principle of application of dose limits: The total dose to any individual from regulated sources in planned
exposure situations other than medical exposure of PATIENTS should not exceed the appropriate limits
recommended by the Commission.”
(d) "Application of dose limits for the PATIENT dose might be to the PATIENT’S detriment. Therefore dose limits
should not be applied to medical exposures. However, considerations should be given to the use of dose
constraints or investigation levels for some common diagnostic procedures. This concept, now renamed as
diagnostic reference levels, has been introduced in a large number of countries."
NOTE 5 It is recognized that many of the judgements necessary to follow the ICRP general principles have to be
made by the RESPONSIBLE ORGANIZATIONS and not by the MANUFACTURER of the ME EQUIPMENT.
201.1.3 Collateral standards
Addition:
This particular standard refers to those applicable collateral standards that are listed in
Clause 2 of the general standard and Clause 201.2 of this particular standard.
IEC 60601-1-3 applies as modified in Clause 203. IEC 60601-1-8, IEC 60601-1-9 and
3)
IEC 60601-1-10 do not apply. All other published collateral standards in the IEC 60601-1
series apply as published.
IEC 60601-1-2 and IEC 60601-1-3 apply as modified in Clauses 202 and 203. IEC 60601-1-8,
4) 5) 6)
IEC 60601-1-9, IEC 60601-1-10 , IEC 60601-1-11 and IEC 60601-1-12 do not apply. All
other published collateral standards in the IEC 60601-1 series apply as published.
For collateral standards published after this particular standard, MANUFACTURERS need to
determine the applicability in accordance with the RISK MANAGEMENT PROCESS.
—————————
2)
Figures in square brackets refer to the Bibliography.
3)
IEC 60601-1-10, Medical electrical equipment – Part 1-10: General requirements for basic safety and essential
performance – Collateral Standard: Requirements for the development of physiologic closed-loop controllers
4)
IEC 60601-1-10, Medical electrical equipment – Part 1-10: General requirements for basic safety and essential
performance – Collateral Standard: Requirements for the development of physiologic closed-loop controllers
5)
IEC 60601-1-11, Medical electrical equipment – Part 1-11: General requirements for basic safety and essential
performance – Collateral Standard: Requirements for medical electrical equipment and medical electrical
systems used in the home healthcare environment
6)
IEC 60601-1-12, Medical electrical equipment – Part 1-12: General requirements for basic safety and essential
performance – Collateral Standard: Requirements for medical electrical equipment and medical electrical
systems intended to be used in the emergency medical services environment
+AMD2:2016 CSV IEC 2016
201.1.4 Particular standards
Replacement:
In the IEC 60601 series, particular standards may modify, replace or delete requirements
contained in the general standard and collateral standards as appropriate for the particular
ME EQUIPMENT under consideration, and may add other BASIC SAFETY and ESSENTIAL
PERFORMANCE requirements.
A requirement of a particular standard takes priority over the general standard.
For brevity, IEC 60601-1 is referred to in this particular standard as the general standard.
Collateral standards are referred to by their document numbers.
The numbering of clauses and subclauses of this particular standard corresponds to that of
the general standard with the prefix “201” (e.g. 201.1 in this standard addresses the content
of Clause 1 of the general standard) or applicable collateral standard with the prefix “20x”
where x is the final digit(s) of the collateral standard document number (e.g. 202.4 in this
particular standard addresses the content of Clause 4 of the 60601-1-2 collateral standard,
203.4 in this particular standard addresses the content of Clause 4 of the 60601-1-3 collateral
standard, etc.). The changes to the text of the general standard are specified by the use of
the following words:
"Replacement" means that the clause or subclause of the general standard or applicable
collateral standard is replaced completely by the text of this particular standard.
"Addition" means that the text of this particular standard is additional to the requirements of
the general standard or applicable collateral standard.
"Amendment" means that the clause or subclause of the general standard or applicable
collateral standard is amended as indicated by the text of this particular standard.
Subclauses, figures or tables which are additional to those of the general standard are
numbered starting from 201.101. However, due to the fact that definitions in the general
standard are numbered 3.1 through 3.139, additional definitions in this standard are
numbered beginning from 201.3.201. Additional annexes are lettered AA, BB, etc., and
additional items aa), bb), etc.
Subclauses, figures or tables which are additional to those of a collateral standard are
numbered starting from 20x, where “x” is the number of the collateral standard, e.g. 202 for
IEC 60601-1-2, 203 for IEC 60601-1-3, etc.
The term "this standard" is used to make reference to the general standard, any applicable
collateral standards and this particular standard taken together.
Where there is no corresponding section, clause or subclause in this particular standard, the
section, clause or subclause of the general standard or applicable collateral standard,
although possibly not relevant, applies without modification; where it is intended that any
parts of the general standard or applicable collateral standard, although possibly relevant, is
not to be applied, a statement to that effect is given in this particular standard.
201.2 Normative references
NOTE Informative references are listed in the bibliography beginning on page 64.
Clause 2 of the general standard applies, except as follows:
– 12 – IEC 60601-2-44:2009+AMD1:2012
+AMD2:2016 CSV IEC 2016
Replacement:
IEC 60601-1-2:2014, 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 60601-1-3:2008/AMD1:2013
Addition:
IEC 60336 Medical electric equipment – X-Ray Tube assemblies for medical diagnosis –
Characteristics of focal spots
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic
safety and essential performance
IEC 60601-1:2005/AMD1:2012
IEC 61223-3-5, Evaluation and routine testing in medical imaging departments – Part 3-5:
Acceptance tests – Imaging performance of computed tomography X-ray equipment
ISO 12052, Health informatics – Digital imaging and communication in medicine (DICOM)
including workflow and data management
201.3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60601-1:2005 and
IEC 60601-1:2005/AMD1:2012, IEC 60601-1-3:2008 and IEC 60601-1-3:2008/AMD1:2013,
and IEC 60788:2004 apply, except as follows:
NOTE 101 An index of defined terms is to be found at the end of this document.
NOTE 102 In accordance with the definitions in IEC 60601-1-3, in this standard unless otherwise indicated:
– values of X-RAY TUBE VOLTAGE refer to peak values, transients being disregarded;
– values of X-RAY TUBE CURRENT refer to average values.
Addition:
201.3.201
CT SCANNER
X-RAY EQUIPMENT intended to generate cross-sectional images of the body by computer
reconstruction of X-ray transmission data obtained at different angles, which may include
signal analysis and display equipment, PATIENT SUPPORT, support parts and ACCESSORIES
NOTE 1 The scope of this document is limited to CT SCANNERS intended to be used for both head and body
characterised by an ENCLOSURE of the X-ray source(s) and imaging detector(s) in a common protective cover in the
shape of a toroid.
NOTE 2 Secondary imaging processing is not included in the scope of this standard.
201.3.202
CT CONDITIONS OF OPERATION
all selectable parameters governing the operation of a CT SCANNER
NOTE 1 Examples of such conditions include NOMINAL TOMOGRAPHIC SECTION THICKNESS, CT PITCH FACTOR,
FILTRATION, peak X-RAY TUBE VOLTAGE and either X-RAY TUBE CURRENT and LOADING TIME or CURRENT TIME PRODUCT.
+AMD2:2016 CSV IEC 2016
NOTE 2 Some CT CONDITIONS OF OPERATION may vary during the exposure.
NOTE 3 CT CONDITIONS OF OPERATION include parameters that are derived by the system from the user-selectable
parameters.
201.3.203
COMPUTED TOMOGRAPHY DOSE INDEX 100
CTDI
integral of the DOSE PROFILE produced in a single axial scan along a line perpendicular to
the TOMOGRAPHIC PLANE from –50 mm to +50 mm, divided by the product of the number of
TOMOGRAPHIC SECTIONS N and the NOMINAL TOMOGRAPHIC SECTION THICKNESS T, or divided by
100 mm, whichever is less:
+50 mm
D (z)
= dz
CTDI100
∫
min{N × T,100 mm}
−50 mm
where
D(z) is the DOSE PROFILE along a line z perpendicular to the TOMOGRAPHIC PLANE, where
dose is reported as ABSORBED DOSE in air and is evaluated within a
polymethylmethacrylate (PMMA) dosimetry PHANTOM (203.108);
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-ray
source;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS.
NOTE 1 The dose is reported as ABSORBED DOSE in air. Air is explicitly designated the reference medium for dose
in order to avoid potential confusion, since some MANUFACTURERS of CT SCANNERS express dose values calculated
as ABSORBED DOSE to air and others as ABSORBED DOSE to PMMA.
Although CTDI refers to ABSORBED DOSE in air, for practical purposes the evaluation of ABSORBED DOSE to air
within a PMMA dosimetry PHANTOM is well approximated by measurement of the AIR KERMA with an ionization
chamber in the PHANTOM. Generally there is traceability of ionization chambers to AIR KERMA.
NOTE 2 This definition assumes that the DOSE PROFILE is centred on z = 0.
NOTE 3 A single axial scan is typically a 360° rotation of the X-ray source.
NOTE 4 When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with “flying FOCAL SPOT”, the product
N × T needs to be adjusted for overlap.
NOTE 5 Typically the z-axis is the axis of rotation.
NOTE 6 If N × T is greater than 100 mm, the physical meaning of CTDI changes from the average dose at the
centre of a 100 mm scan length to the average dose over the central 100 mm region for a single axial scan.
NOTE 7 The value of CTDI will be lower if the length of the dosimetry PHANTOM is less than N × T + 100 mm,
since the contribution from scattered RADIATION will be underestimated.
integral of the DOSE PROFILE representative of a single axial scan along a line perpendicular to
the TOMOGRAPHIC PLANE divided by N x T according to the following:
for N × T less than or equal to 40 mm
+50 mm
D (z)
= dz
CTDI
∫
N × T
−50 mm
for N × T greater than 40 mm (all CT CONDITIONS OF OPERATION except collimation are kept the
same for these measurements)
+50 mm
CTDI
D (z)
Ref free air, N×T
= dz×
CTDI100
∫
(N×T) CTDI
Ref free air, Ref
−50 mm
– 14 – IEC 60601-2-44:2009+AMD1:2012
+AMD2:2016 CSV IEC 2016
where
D(z) is the DOSE PROFILE representative of a single axial scan along a line z
perpendicular to the TOMOGRAPHIC PLANE, where dose is reported as
ABSORBED DOSE in air and is evaluated within a polymethylmethacrylate
(PMMA) dosimetry PHANTOM (see 203.108);
(N × T) is a specific N × T of 20 mm or the largest N × T available not greater than
Ref
20 mm;
D (z) is the DOSE PROFILE representative of a single axial scan along a line z
Ref
perpendicular to the TOMOGRAPHIC PLANE, where dose is reported as
ABSORBED DOSE in air and is evaluated within a polymethylmethacrylate
(PMMA) dosimetry PHANTOM (see 203.108) for (N × T) ;
Ref
CTDI is the CTDI (201.3.215) for a specific value of N × T;
free air, N × T free air
CTDI is the CTDI (201.3.215) for (N × T) ;
free air, Ref free air Ref
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of
the X-ray source;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS.
NOTE 1 The dose is reported as ABSORBED DOSE to air, but for practical purposes the evaluation of ABSORBED
DOSE to air within a PMMA dosimetry PHANTOM is well approximated by measurement of the AIR KERMA.
NOTE 2 This definition assumes that the DOSE PROFILE is centred on z = 0.
NOTE 3 A single axial scan is typically a 360° rotation of the X-ray source.
NOTE 4 When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with a “z-flying FOCAL SPOT”, the
denominator of the integral needs to be replaced by the total nominal width along z of overlapping tomographic
sections. For example, if the percentage of overlap is 50%, then the denominator would be replaced by 0,5 × N × T.
NOTE 5 Typically the z-axis is the axis of rotation.
NOTE 6 The CTDI is designed to include most of the scattered radiation.
NOTE 7 See Annex CC for explanation.
y
T
x
z
IEC 369/09
1 TOMOGRAPHIC PLANE
2 PHANTOM
Figure 201.101 – Coordinate system
+AMD2:2016 CSV IEC 2016
201.3.204
CT PITCH FACTOR
in helical scanning the ratio of the PATIENT SUPPORT travel Δd along the z-direction per rotation
of the X-ray source divided by the product of the NOMINAL TOMOGRAPHIC SECTION THICKNESS T
and the number of TOMOGRAPHIC SECTIONS N:
Δd
CT pitch factor =
N×T
where
∆d is the PATIENT SUPPORT travel along the z-direction per rotation of the X-RAY SOURCE;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS;
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-RAY
SOURCE.
NOTE 1 Although the CT PITCH FACTOR is associated with helical scanning, its definition refers to parameters T
and N that are defined only for axial scanning. Definition 201.3.204 presumes that these axial-scanning parameters
T and N correspond to the same collimation and active-detector configuration as that of the helical scanning for
which the CT PITCH FACTOR is being evaluated.
NOTE 2 When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with “flying FOCAL SPOT”, the product
N × T needs to be adjusted for overlap.
NOTE 3 CT PITCH FACTOR will be a function of time when ∆d or N × T are is variable during the exposure.
NOTE 4 The terms “helical” is used in this document as a synonym for the term “spiral”.
201.3.205
DOSE PROFILE
representation of the dose as a function of position along a line
201.3.206
NOMINAL TOMOGRAPHIC SECTION THICKNESS
in CT SCANNERS the TOMOGRAPHIC SECTION THICKNESS which is selected and indicated on the
CONTROL PANEL
NOTE In helical scanning the thickness of a section associated with the reconstructed image depends on the
helical reconstruction algorithm and pitch. This thickness might or might not be equal to the NOMINAL TOMOGRAPHIC
SECTION THICKNESS.
201.3.207
SENSITIVITY PROFILE
relative response of a system for COMPUTED TOMOGRAPHY as a function of position along a line
perpendicular to the TOMOGRAPHIC PLANE
201.3.208
TOMOGRAPHIC PLANE
geometric plane perpendicular to the axis of rotation at the centre of the X-RAY FIELD in z (see
Figure 201.101)
201.3.209
TOMOGRAPHIC SECTION
for CT SCANNERS with a single detector row, the volume over which TRANSMISSION data of
X-RADIATION are collected in a single axial scan; for CT SCANNERS with multiple detector rows
along the z-axis, the volume over which data are collected by a single acquisition channel
representing a single row or a selected grouping of rows
201.3.210
TOMOGRAPHIC SECTION THICKNESS
FULL WIDTH AT HALF MAXIMUM of the SENSITIVITY PROFILE taken at the ISOCENTRE of a
TOMOGRAPHIC SECTION
– 16 – IEC 60601-2-44:2009+AMD1:2012
+AMD2:2016 CSV IEC 2016
201.3.211
WEIGHTED CTDI
CTDI
w
value defined as
1 2
CTDI = CTDI + CTDI
W 100(centre ) 100(peripheral)
3 3
where CTDI is the value of CTDI measured in the centre of a dosimetry PHANTOM,
100(centre) 100
and where CTDI is the average of the four values of CTDI measured around
100(peripheral) 100
the dosimetry PHANTOM periphery according to 203.109.1 a)2) and 3)
201.3.212
VOLUME CTDI
w
CTDI
vol
a) for axial scanning
N×T
CTDI = CTDI
vol w
Δ d
where
N is
...
IEC 60601-2-44 ®
Edition 3.1 2012-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Medical electrical equipment –
Part 2-44: Particular requirements for the basic safety and essential performance
of X-ray equipment for computed tomography
Appareils électromédicaux –
Partie 2-44: Exigences particulières pour la sécurité de base et les performances
essentielles des équipements à rayonnement X de tomodensitométrie
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IEC 60601-2-44 ®
Edition 3.1 2012-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Medical electrical equipment –
Part 2-44: Particular requirements for the basic safety and essential performance
of X-ray equipment for computed tomography
Appareils électromédicaux –
Partie 2-44: Exigences particulières pour la sécurité de base et les performances
essentielles des équipements à rayonnement X de tomodensitométrie
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX CT
ICS 11.040.50 ISBN 978-2-8322-0346-0
– 2 – 60601-2-44 IEC:2009+A1:2012
CONTENTS
FOREWORD . 3
Introduction to Amendment 1 . 5
201.1 Scope, object and related standards. 6
201.2 Normative references . 8
201.3 Terms and definitions . 9
201.4 General requirements . 17
201.5 General requirements for testing of ME EQUIPMENT . 18
201.6 Classification of ME EQUIPMENT and ME SYSTEMS . 18
201.7 ME EQUIPMENT identification, marking and documents . 19
201.8 Protection against electrical HAZARDS from ME EQUIPMENT . 21
201.9 Protection against mechanical HAZARDS of ME EQUIPMENT and ME SYSTEMS . 24
201.10 Protection against unwanted and excessive RADIATION HAZARDS . 27
201.11 Protection against excessive temperatures and other HAZARDS . 28
201.12 Accuracy of controls and instruments and protection against hazardous
outputs . 28
201.13 Hazardous situations and fault conditions . 29
201.14 PROGRAMMABLE ELECTRICAL MEDICAL SYSTEMS (PEMS) . 29
201.15 Construction of ME EQUIPMENT . 29
201.16 ME SYSTEMS. 29
201.17 ELECTROMAGNETIC COMPATIBILITY of ME EQUIPMENT and ME SYSTEMS . 29
202 Electromagnetic compatibility – Requirements and tests . 35
203 General requirements for RADIATION protection in diagnostic X-ray equipment . 35
Annexes . 52
Annex AA (informative) Choosing LOADING FACTORS for tests . 52
Annex BB (informative) Estimating CTDI for scan projection RADIOGRAPHY (SPR) . 53
vol
Annex CC (informative) The CTDI concept in IEC 60601-2-44: Relationship
between CTDI and CTDI . 54
100 ∞
Annex DD (informative) Measuring CTDI . 58
free air
Bibliography . 60
Index of defined terms used in this particular standard. 62
Figure 201.101 – Coordinate system . 11
Figure 201.102 – Illustration of N × T, R and (N × T) + R . 14
Figure 201.103 – Vertical alignment of the PATIENT SUPPORT . 30
Figure 201.104 – Z-axis alignment of the PATIENT SUPPORT in the horizontal plane . 32
Figure 203.101 – Zone of extra-focal RADIATION . 41
Figure 203.102 – Minimum dimensions for STRAY RADIATION measurement . 43
Figure CC.1 – CTDI versus beam width along z . 55
w
Table 203.101 − Test pattern for CTDI . 48
free air
Table CC.1 – Ratios of CTDI by phantom length . 57
60601-2-44 IEC:2009+A1:2012 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-44: Particular requirements for the basic safety and essential
performance of X-ray equipment for computed tomography
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
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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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.
This consolidated version of IEC 60601-2-44 consists of the third edition (2009)
[documents 62B/727/FDIS and 62B/734/RVD], its amendment 1 (2012) [documents
62B/879/FDIS and 62B/890/RVD] and its corrigendum of May 2010. It bears the edition
number 3.1.
The technical content is therefore identical to the base edition and its amendment and
has been prepared for user convenience. A vertical line in the margin shows where the
base publication has been modified by amendment 1. Additions and deletions are
displayed in red, with deletions being struck through.
– 4 – 60601-2-44 IEC:2009+A1:2012
International standard IEC 60601-2-44 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this standard, the following print types are used:
– Requirements and definitions: roman type.
– Test specifications: italic type.
– Informative material appearing outside of tables, such as notes, examples and references: in smaller type.
Normative text of tables is also in a smaller type.
– TERMS DEFINED IN CLAUSE 3 OF THE GENERAL STANDARD, IN THIS PARTICULAR STANDARD OR AS
NOTED: SMALL CAPITALS.
In referring to the structure of this standard, the term
– “clause” means one of the seventeen numbered divisions within the table of contents,
inclusive of all subdivisions (e.g. Clause 7 includes subclauses 7.1, 7.2, etc.);
– “subclause” means a numbered subdivision of a clause (e.g. 7.1, 7.2 and 7.2.1 are all
subclauses of Clause 7).
References to clauses within this standard are preceded by the term “Clause” followed by the
clause number. References to subclauses within this particular standard are by number only.
In this standard, the conjunctive “or” is used as an “inclusive or” so a statement is true if any
combination of the conditions is true.
The verbal forms used in this standard conform to usage described in Annex H of the ISO/IEC
Directives, Part 2. For the purposes of this standard, the auxiliary verb:
– “shall” means that compliance with a requirement or a test is mandatory for compliance
with this standard;
– “should” means that compliance with a requirement or a test is recommended but is not
mandatory for compliance with this standard;
– “may” is used to describe a permissible way to achieve compliance with a requirement or test.
A list of all parts of the IEC 60601 series, published under the general title Medical electrical
equipment, can be found on the IEC website.
The committee has decided that the contents of the base publication and its amendments 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.
NOTE The attention of National Committees is drawn to the fact that equipment MANUFACTURERS and testing
organizations may need a transitional period following publication of a new, amended or revised IEC publication in
which to make products in accordance with the new requirements and to equip themselves for conducting new or
revised tests. It is the recommendation of the committee that the content of this publication be adopted for
implementation nationally not earlier than 3 years from the date of publication.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.
60601-2-44 IEC:2009+A1:2012 – 5 –
Introduction to Amendment 1
The main topic addressed in this amendment is an extended concept of CTDI to
accommodate CT SCANNERS with very large z-coverage. The other principal subject areas
include:
1) a dose-check feature associated with a pre-scanning alert if expected values of dose
indices exceed user-configurable DOSE NOTIFICATION VALUES or DOSE ALERT VALUES and
2) requirements covering the use of CT data in radiotherapy treatment planning (RTP).
The CT dose metric in use has been based on the CTDI , i.e. measurement of dose in
PHANTOMs and limited integration of scattered radiation, and it is used in many countries’
legislation to define "dose reference values" (also called "diagnostic reference levels") for CT
examinations. Many people use these indices, CTDI and DLP, to derive estimates for
vol
effective dose via conversion factors. CTDI is also part of CT acceptance and constancy
testing. The introduction of a new dose index would change all CT SCANNERS’ CTDI values.
Therefore the intention is to stay with the CTDI , i.e. the integration of primary radiation and
scatter over 100 mm, but adapt the way of measuring and reporting the dose index to
incorporate large collimations and to rate all collimations the same way, i.e. to reflect
approximately the same percentage of CTDI for all collimations.
∞
As defined in the amendment, CTDI is to be measured only for collimations up to 40 mm
with the current equipment, i.e. the PMMA PHANTOMs and a 100-mm chamber, or other
suitable methods that use a RADIATION DETECTOR. For these collimations there is no significant
change of the ratio CTDI / CTDI according to published data. For larger collimations at
100 ∞
the same CT CONDITIONS OF OPERATION, the z-efficiency may be different and must be
evaluated in the dose measurement. This can be accomplished by the measurement of dose
‘free air’. Based on these considerations CTDI and the CTDI have been refined. Both
100 free air
types of measurement are combined now to determine the CTDI values for larger collimations
and they are explained in detail in informative Annexes CC and DD.
Some additional requirements and refinements related to dose have been added: CTDI and
vol
DLP are defined for a new type of scan mode (‘shuttle mode’). In body CT EXAMINATION it is
clarified that the CTDI and DLP always be reported for the 32-cm diameter PHANTOM. In the
vol
amendment it is now required that CT SCANNERS support user-configurable DOSE NOTIFICATION
VALUES and DOSE ALERT VALUES.
A new subject area in this Amendment 1 covers requirements for CT SCANNERS providing
images for radiotherapy treatment planning. With this amendment begins the implementation
of this important CT application into the CT safety standard with a set of requirements that is
considered to be safety relevant. It mainly covers scanner hardware adjustments, accuracy of
CT image data, and the conversion of HU to electron and mass density.
– 6 – 60601-2-44 IEC:2009+A1:2012
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-44: Particular requirements for the basic safety and essential
performance of X-ray equipment for computed tomography
201.1 Scope, object and related standards
1)
Clause 1 of the general standard applies, except as follows:
201.1.1 Scope
Replacement:
This International Standard applies to the BASIC SAFETY and ESSENTIAL PERFORMANCE of CT
SCANNERS, hereafter also referred to as ME EQUIPMENT.
If a clause or subclause is specifically intended to be applicable to ME EQUIPMENT only, or to
ME SYSTEMS only, the title and content of that clause or subclause will say so. If that is not the
case, the clause or subclause applies both to ME EQUIPMENT and to ME SYSTEMS, as relevant.
NOTE 1 See also 4.2 of the general standard.
The scope of this document is limited to CT SCANNERS intended to be used for both head and
body characterised by an ENCLOSURE of the X-ray source(s) and imaging detector(s) in a
common protective cover in the shape of a toroid. It includes safety requirements for the X-
RAY GENERATORS used in CT SCANNERS, including those where HIGH-VOLTAGE GENERATORS are
integrated with an X-RAY TUBE ASSEMBLY.
NOTE 2 Requirements for X-RAY GENERATORS and for ASSOCIATED EQUIPMENT, which were previously specified in
IEC 60601-2-7 and IEC 60601-2-32, have been included in either IEC 60601-1:2005 (Ed3) or this edition of
rd
IEC 60601-2-44. Therefore IEC 60601-2-7 and IEC 60601-2-32 are not part of the 3 edition scheme for COMPUTED
TOMOGRAPHY.
The scope of this International Standard excludes RADIOTHERAPY SIMULATORS and systems
where the image is created by a source other than an X-RAY TUBE.
201.1.2 Object
Replacement:
The object of this particular standard is to establish particular BASIC SAFETY and ESSENTIAL
PERFORMANCE requirements for CT SCANNERS as defined in 201.3.201, to ensure safety, and to
specify methods for demonstrating compliance with those requirements, for CT SCANNERS.
NOTE 1 Requirements for reproducibility, linearity, constancy and accuracy are given because of their
relationship to the quality and quantity of the IONIZING RADIATION produced and are confined to those considered
necessary for safety.
NOTE 2 Both the levels for compliance and the tests prescribed to determine compliance reflect the fact that the
safety of HIGH-VOLTAGE GENERATORS is not sensitive to small differences in levels of performance. The
combinations of LOADING FACTORS specified for the tests are therefore limited in number but chosen from
experience as being appropriate in most cases. It is considered important to standardize the choice of
combinations of LOADING FACTORS so that comparison can be made between tests performed in different places on
different occasions. However, combinations other than those specified could be of equal technical validity.
—————————
1)
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic safety and essential
performance.
60601-2-44 IEC:2009+A1:2012 – 7 –
NOTE 3 The safety philosophy on which this standard is based is described in the introduction to the general
standard and in IEC TR 60513.
NOTE 4 Concerning RADIOLOGICAL PROTECTION, it is assumed that MANUFACTURERS and RESPONSIBILE
ORGANIZATIONS accept the general principles of justification, optimisation, and application of dose limits of the
2)
International Commission on Radiological Protection as stated in ICRP 103, 2007, paragraph 203, [12] namely:
(a) “The principle of justification: Any decision that alters the RADIATION exposure situation should do more good
than harm.”
(b) “The principle of optimisation of protection: The likelihood of incurring exposures, the number of people
exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable, taking
into account economic and societal factors.”
(c) “The principle of application of dose limits: The total dose to any individual from regulated sources in planned
exposure situations other than medical exposure of PATIENTS should not exceed the appropriate limits
recommended by the Commission.”
(d) "Application of dose limits for the PATIENT dose might be to the PATIENT’S detriment. Therefore dose limits
should not be applied to medical exposures. However, considerations should be given to the use of dose
constraints or investigation levels for some common diagnostic procedures. This concept, now renamed as
diagnostic reference levels, has been introduced in a large number of countries."
NOTE 5 It is recognized that many of the judgements necessary to follow the ICRP general principles have to be
made by the RESPONSIBLE ORGANIZATIONS and not by the MANUFACTURER of the ME EQUIPMENT.
201.1.3 Collateral standards
Addition:
This particular standard refers to those applicable collateral standards that are listed in
Clause 2 of the general standard and Clause 201.2 of this particular standard.
IEC 60601-1-3 applies as modified in Clause 203. IEC 60601-1-8, IEC 60601-1-9 and
3)
IEC 60601-1-10 do not apply. All other published collateral standards in the IEC 60601-1
series apply as published.
IEC 60601-1-2 and IEC 60601-1-3 apply as modified in Clauses 202 and 203. IEC 60601-1-8,
4) 5) 6)
IEC 60601-1-9, IEC 60601-1-10 , IEC 60601-1-11 and IEC 60601-1-12 do not apply. All
other published collateral standards in the IEC 60601-1 series apply as published.
For collateral standards published after this particular standard, MANUFACTURERS need to
determine the applicability in accordance with the RISK MANAGEMENT PROCESS.
—————————
2)
Figures in square brackets refer to the Bibliography.
3)
IEC 60601-1-10, Medical electrical equipment – Part 1-10: General requirements for basic safety and essential
performance – Collateral Standard: Requirements for the development of physiologic closed-loop controllers
4)
IEC 60601-1-10, Medical electrical equipment – Part 1-10: General requirements for basic safety and essential
performance – Collateral Standard: Requirements for the development of physiologic closed-loop controllers
5)
IEC 60601-1-11, Medical electrical equipment – Part 1-11: General requirements for basic safety and essential
performance – Collateral Standard: Requirements for medical electrical equipment and medical electrical
systems used in the home healthcare environment
6)
IEC 60601-1-12, Medical electrical equipment – Part 1-12: General requirements for basic safety and essential
performance – Collateral Standard: Requirements for medical electrical equipment and medical electrical
systems intended to be used in the emergency medical services environment
– 8 – 60601-2-44 IEC:2009+A1:2012
201.1.4 Particular standards
Replacement:
In the IEC 60601 series, particular standards may modify, replace or delete requirements
contained in the general standard and collateral standards as appropriate for the particular
ME EQUIPMENT under consideration, and may add other BASIC SAFETY and ESSENTIAL
requirements.
PERFORMANCE
A requirement of a particular standard takes priority over the general standard.
For brevity, IEC 60601-1 is referred to in this particular standard as the general standard.
Collateral standards are referred to by their document numbers.
The numbering of clauses and subclauses of this particular standard corresponds to that of
the general standard with the prefix “201” (e.g. 201.1 in this standard addresses the content
of Clause 1 of the general standard) or applicable collateral standard with the prefix “20x”
where x is the final digit(s) of the collateral standard document number (e.g. 202.4 in this
particular standard addresses the content of Clause 4 of the 60601-1-2 collateral standard,
203.4 in this particular standard addresses the content of Clause 4 of the 60601-1-3 collateral
standard, etc.). The changes to the text of the general standard are specified by the use of
the following words:
"Replacement" means that the clause or subclause of the general standard or applicable
collateral standard is replaced completely by the text of this particular standard.
"Addition" means that the text of this particular standard is additional to the requirements of
the general standard or applicable collateral standard.
"Amendment" means that the clause or subclause of the general standard or applicable
collateral standard is amended as indicated by the text of this particular standard.
Subclauses, figures or tables which are additional to those of the general standard are
numbered starting from 201.101. However, due to the fact that definitions in the general
standard are numbered 3.1 through 3.139, additional definitions in this standard are
numbered beginning from 201.3.201. Additional annexes are lettered AA, BB, etc., and
additional items aa), bb), etc.
Subclauses, figures or tables which are additional to those of a collateral standard are
numbered starting from 20x, where “x” is the number of the collateral standard, e.g. 202 for
IEC 60601-1-2, 203 for IEC 60601-1-3, etc.
The term "this standard" is used to make reference to the general standard, any applicable
collateral standards and this particular standard taken together.
Where there is no corresponding section, clause or subclause in this particular standard, the
section, clause or subclause of the general standard or applicable collateral standard,
although possibly not relevant, applies without modification; where it is intended that any
parts of the general standard or applicable collateral standard, although possibly relevant, is
not to be applied, a statement to that effect is given in this particular standard.
201.2 Normative references
NOTE Informative references are listed in the bibliography beginning on page 60.
Clause 2 of the general standard applies, except as follows:
60601-2-44 IEC:2009+A1:2012 – 9 –
Replacement:
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
Addition:
IEC 60336 Medical electric equipment – X-Ray Tube assemblies for medical diagnosis –
Characteristics of focal spots
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic
safety and essential performance
IEC 61223-3-5, Evaluation and routine testing in medical imaging departments – Part 3-5:
Acceptance tests – Imaging performance of computed tomography X-ray equipment
ISO 12052, Health informatics – Digital imaging and communication in medicine (DICOM)
including workflow and data management
201.3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60601-1:2005, IEC
60601-1-3:2008 and IEC 60788:2004 apply, except as follows:
NOTE 101 An index of defined terms is to be found at the end of this document.
NOTE 102 In accordance with the definitions in IEC 60601-1-3, in this standard unless otherwise indicated:
– values of X-RAY TUBE VOLTAGE refer to peak values, transients being disregarded;
– values of X-RAY TUBE CURRENT refer to average values.
Addition:
201.3.201
CT SCANNER
X-RAY EQUIPMENT intended to generate cross-sectional images of the body by computer
reconstruction of X-ray transmission data obtained at different angles, which may include
signal analysis and display equipment, PATIENT SUPPORT, support parts and ACCESSORIES
NOTE 1 The scope of this document is limited to CT SCANNERS intended to be used for both head and body
characterised by an ENCLOSURE of the X-ray source(s) and imaging detector(s) in a common protective cover in the
shape of a toroid.
NOTE 2 Secondary imaging processing is not included in the scope of this standard.
201.3.202
CONDITIONS OF OPERATION
CT
all selectable parameters governing the operation of a CT SCANNER
NOTE 1 Examples of such conditions include NOMINAL TOMOGRAPHIC SECTION THICKNESS, CT PITCH FACTOR,
FILTRATION, peak X-RAY TUBE VOLTAGE and either X-RAY TUBE CURRENT and LOADING TIME or CURRENT TIME PRODUCT.
NOTE 2 Some CT CONDITIONS OF OPERATION may vary during the exposure.
– 10 – 60601-2-44 IEC:2009+A1:2012
NOTE 3 CT CONDITIONS OF OPERATION include parameters that are derived by the system from the user-selectable
parameters.
201.3.203
COMPUTED TOMOGRAPHY DOSE INDEX 100
CTDI
integral of the DOSE PROFILE produced in a single axial scan along a line perpendicular to
the TOMOGRAPHIC PLANE from –50 mm to +50 mm, divided by the product of the number of
TOMOGRAPHIC SECTIONS N and the NOMINAL TOMOGRAPHIC SECTION THICKNESS T, or divided by
100 mm, whichever is less:
+50 mm
D (z)
= dz
CTDI100
∫
min{N × T,100 mm}
−50 mm
where
D(z) is the DOSE PROFILE along a line z perpendicular to the TOMOGRAPHIC PLANE, where
dose is reported as ABSORBED DOSE in air and is evaluated within a
polymethylmethacrylate (PMMA) dosimetry PHANTOM (203.108);
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-ray
source;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS.
NOTE 1 The dose is reported as ABSORBED DOSE in air. Air is explicitly designated the reference medium for dose
in order to avoid potential confusion, since some MANUFACTURERS of CT SCANNERS express dose values calculated
as ABSORBED DOSE to air and others as ABSORBED DOSE to PMMA.
Although CTDI refers to ABSORBED DOSE in air, for practical purposes the evaluation of ABSORBED DOSE to air
within a PMMA dosimetry PHANTOM is well approximated by measurement of the AIR KERMA with an ionization
chamber in the PHANTOM. Generally there is traceability of ionization chambers to AIR KERMA.
NOTE 2 This definition assumes that the DOSE PROFILE is centred on z = 0.
NOTE 3 A single axial scan is typically a 360° rotation of the X-ray source.
NOTE 4 When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with “flying FOCAL SPOT”, the product
N × T needs to be adjusted for overlap.
NOTE 5 Typically the z-axis is the axis of rotation.
NOTE 6 If N × T is greater than 100 mm, the physical meaning of CTDI changes from the average dose at the
centre of a 100 mm scan length to the average dose over the central 100 mm region for a single axial scan.
NOTE 7 The value of CTDI will be lower if the length of the dosimetry PHANTOM is less than N × T + 100 mm,
since the contribution from scattered RADIATION will be underestimated.
integral of the DOSE PROFILE representative of a single axial scan along a line perpendicular to
the TOMOGRAPHIC PLANE divided by N x T according to the following:
for N × T less than or equal to 40 mm
+50 mm
D (z)
= dz
CTDI
∫
N × T
−50 mm
for N × T greater than 40 mm (all CT CONDITIONS OF OPERATION except collimation are kept the
same for these measurements)
+50 mm
CTDI
D (z)
free air, N×T
Ref
= dz×
CTDI
∫
(N×T) CTDI
Ref free air, Ref
−50 mm
60601-2-44 IEC:2009+A1:2012 – 11 –
where
D(z) is the DOSE PROFILE representative of a single axial scan along a line z
perpendicular to the TOMOGRAPHIC PLANE, where dose is reported as
ABSORBED DOSE in air and is evaluated within a polymethylmethacrylate
(PMMA) dosimetry PHANTOM (see 203.108);
(N × T) is a specific N × T of 20 mm or the largest N × T available not greater than
Ref
20 mm;
D (z) is the DOSE PROFILE representative of a single axial scan along a line z
Ref
perpendicular to the TOMOGRAPHIC PLANE, where dose is reported as
ABSORBED DOSE in air and is evaluated within a polymethylmethacrylate
(PMMA) dosimetry PHANTOM (see 203.108) for (N × T) ;
Ref
CTDI is the CTDI (201.3.215) for a specific value of N × T;
free air, N × T free air
CTDI is the CTDI (201.3.215) for (N × T) ;
free air, Ref free air Ref
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of
the X-ray source;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS.
NOTE 1 The dose is reported as ABSORBED DOSE to air, but for practical purposes the evaluation of ABSORBED
DOSE to air within a PMMA dosimetry PHANTOM is well approximated by measurement of the AIR KERMA.
NOTE 2 This definition assumes that the DOSE PROFILE is centred on z = 0.
NOTE 3 A single axial scan is typically a 360° rotation of the X-ray source.
NOTE 4 When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with a “z-flying FOCAL SPOT”, the
denominator of the integral needs to be replaced by the total nominal width along z of overlapping tomographic
sections. For example, if the percentage of overlap is 50%, then the denominator would be replaced by 0,5 × N × T.
NOTE 5 Typically the z-axis is the axis of rotation.
NOTE 6 The CTDI is designed to include most of the scattered radiation.
NOTE 7 See Annex CC for explanation.
y
T
x
z
IEC 369/09
1 TOMOGRAPHIC PLANE
2 PHANTOM
Figure 201.101 – Coordinate system
– 12 – 60601-2-44 IEC:2009+A1:2012
201.3.204
CT PITCH FACTOR
in helical scanning the ratio of the PATIENT SUPPORT travel Δd along the z-direction per rotation
of the X-ray source divided by the product of the NOMINAL TOMOGRAPHIC SECTION THICKNESS T
and the number of TOMOGRAPHIC SECTIONS N:
Δd
CT pitch factor =
N×T
where
∆d is the PATIENT SUPPORT travel along the z-direction per rotation of the X-RAY SOURCE;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS;
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-RAY
SOURCE.
NOTE 1 Although the CT PITCH FACTOR is associated with helical scanning, its definition refers to parameters T
and N that are defined only for axial scanning. Definition 201.3.204 presumes that these axial-scanning parameters
T and N correspond to the same collimation and active-detector configuration as that of the helical scanning for
which the CT PITCH FACTOR is being evaluated.
NOTE 2 When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with “flying FOCAL SPOT”, the product
N × T needs to be adjusted for overlap.
NOTE 3 CT PITCH FACTOR will be a function of time when ∆d or N × T are is variable during the exposure.
NOTE 4 The terms “helical” is used in this document as a synonym for the term “spiral”.
201.3.205
DOSE PROFILE
representation of the dose as a function of position along a line
201.3.206
NOMINAL TOMOGRAPHIC SECTION THICKNESS
in CT SCANNERS the TOMOGRAPHIC SECTION THICKNESS which is selected and indicated on the
CONTROL PANEL
NOTE In helical scanning the thickness of a section associated with the reconstructed image depends on the
helical reconstruction algorithm and pitch. This thickness might or might not be equal to the NOMINAL TOMOGRAPHIC
SECTION THICKNESS.
201.3.207
SENSITIVITY PROFILE
relative response of a system for COMPUTED TOMOGRAPHY as a function of position along a line
perpendicular to the TOMOGRAPHIC PLANE
201.3.208
TOMOGRAPHIC PLANE
geometric plane perpendicular to the axis of rotation at the centre of the X-RAY FIELD in z (see
Figure 201.101)
201.3.209
TOMOGRAPHIC SECTION
for CT SCANNERS with a single detector row, the volume over which TRANSMISSION data of
X-RADIATION are collected in a single axial scan; for CT SCANNERS with multiple detector rows
along the z-axis, the volume over which data are collected by a single acquisition channel
representing a single row or a selected grouping of rows
201.3.210
TOMOGRAPHIC SECTION THICKNESS
FULL WIDTH AT HALF MAXIMUM of the SENSITIVITY PROFILE taken at the ISOCENTRE of a
TOMOGRAPHIC SECTION
60601-2-44 IEC:2009+A1:2012 – 13 –
201.3.211
WEIGHTED CTDI
CTDI
w
value defined as
1 2
CTDI = CTDI + CTDI
W 100(centre ) 100(peripheral)
3 3
where CTDI is the value of CTDI measured in the centre of a dosimetry PHANTOM,
100(centre) 100
and where CTDI is the average of the four values of CTDI measured around
100(peripheral) 100
the dosimetry PHANTOM periphery according to 203.109.1 a)2) and 3)
201.3.212
VOLUME CTDI
w
CTDI
vol
a) for axial scanning
N×T
CTDI = CTDI
vol w
Δ d
where
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-
ray source;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS;
∆d is the PATIENT SUPPORT travel in z-direction between consecutive scans.
NOTE 1 For axial scanning with a total table travel of less than N × T this definition may overestimate the dose.
NOTE 2 For the selected CT CONDTIONS OF OPERATION, but irrespective of any scanning length that may be used
clinically, the VOLUME CTDI (CTDI ) is an index of dose based on a convention of 100 mm range of integration
w vol
along the z-axis. For axial scanning, CTDI corresponds to the average dose that would accrue in the PHANTOM
vol
central section of volume equal to the cross sectional area × ∆d .
NOTE 1 For the selected CT CONDITIONS OF OPERATION, but irrespective of any scanning length that may be used
clinically, the VOLUME CTDI (CTDI ) is an index of dose based on a convention of 100 mm range of integration
w vol
along the z-axis. For axial scanning, CTDI corresponds to the average dose that would accrue in the PHANTOM
vol
central section of volume equal to the cross sectional area × ∆d.
NOTE 2 For axial scanning with a total table travel much less than N × T, CTDI as defined overestimates the
vol
average dose that would accrue in the PHANTOM central section of volume equal to the cross sectional area ×Δd.
b) for helical scanning
CTDI
w
CTDI =
vol
CT pitch factor
NOTE 1 CT PITCH FACTOR will be a function of time when ∆d or N × T are is variable during the exposure.
NOTE 2 For helical scanning with a small number of rotations and a table travel per rotation of less than N × T
this definition may overestimate the dose.
NOTE 3 For the selected CT CONDTIONS OF OPERATION, but irrespective of any scanning length that may be used
clinically, the VOLUME CTDI (CTDI ) is an index of dose based on a convention of 100 mm range of integration
w vol
along the z-axis. For helical scanning, CTDI corresponds to the average dose that would accrue in the PHANTOM
vol
central section of volume equal to the cross sectional area × ∆d.
NOTE 2 For the selected CT CONDITIONS OF OPERATION, but irrespective of any scanning length that may be used
clinically, the VOLUME CTDI (CTDI ) is an index of dose based on a convention of 100 mm range of integration
w vol
along the z-axis. For helical scanning, CTDI corresponds to the average dose that would accrue in the centre of
vol
a 100 mm scan length.
NOTE 3 For helical scanning, when the product of a small number of rotations times the table travel per rotation
is much less than N × T, CTDI as defined overestimates the average dose that would accrue in the centre of a
vol
100-mm scan length.
– 14 – 60601-2-44 IEC:2009+A1:2012
c) for scanning without movement of the PATIENT SUPPORT
CTDI = n × CTDI
vol w
where n is equal to the number of rotations.
NOTE 1 c) includes situations where the PATIENT SUPPORT may be moved manually, for example, during an
interventional procedure.
NOTE 2 For scanning without movement of the PATIENT SUPPORT and for situations where the PATIENT SUPPORT
may be moved manually, this definition overestimates the dose as it includes assumed scatter contribution from
adjacent slices.
NOTE 3 For scanni
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