IEC 60601-2-68:2014

Medical electrical equipment - Part 2-68: Particular requirements for the basic safety and essential performance of X-ray-based image-guided radiotherapy equipment for use with electron accelerators, light ion beam therapy equipment and radionuclide beam therapy equipment

IEC 60601-2-68:2014 applies to the basic safety and essential performance of X-ray based image-guided radiotherapy (IGRT) equipment for use with External Beam Equipment (EBE). This particular standard covers safety aspects of kilovoltage and megavoltage X-ray imaging devices in a known geometrical relationship with EBE for the purpose of IGRT. It covers aspects of communication and relationships between the EBE and X-ray imaging devices, attached or not directly attached to, but in the same radiation shielded area as, and dedicated for use only with, the EBE. This particular standard deals with equipment for real-time X-IGRT, online X-IGRT and offline X-IGRT. It covers procedures to reduce the risk of over-reliance on the X-IGRT EBE systems. For example the manufacturer will provide an interactive interface for user interaction with the correction suggested by the system.

Appareils électromédicaux - Partie 2-68: Exigences particulières pour la sécurité de base et les performances essentielles des appareils de radiothérapie à rayonnement X assistée par imagerie médicale, destinés à être utilisés avec les accélérateurs d'électrons, les appareils de thérapie par faisceau d'ions légers et les appareils de thérapie par faisceau de radionucléides

L'IEC 60601-2-68:2014 s'applique à la sécurité de base et aux performances essentielles des appareils de radiothérapie assistée par imagerie médicale (IGRT) destinés à être utilisés avec les appareils de radiothérapie externes (EBE). La présente norme particulière couvre les aspects de sécurité des dispositifs d'imagerie à rayonnement X sous kilotension et sous mégatension dans une relation géométrique connue avec les EBE à des fins de IGRT. Elle couvre les aspects de communication et les relations entre les EBE et les dispositifs d'imagerie à rayonnement X fixés ou non directement fixés, mais présents dans la même zone protégée contre le rayonnement que les EBE, et dédiés à être utilisés uniquement avec ces appareils. La présente norme particulière traite des appareils de radiothérapie assistée par imagerie médicale en temps réel, en ligne et hors ligne. Elle couvre les procédures de réduction du risque de confiance excessive envers le système d'appareils de radiothérapie assistée par imagerie médicale. Par exemple, le fabricant fournit une interface interactive destinée à l'interaction des utilisateurs avec la correction proposée par le système.

General Information

• Status: Published
• Publication Date: 03-Sep-2014
• ICS: 11.040.60 - Therapy equipment
• Technical Committee: SC 62C - Equipment for radiotherapy, nuclear medicine and radiation dosimetry
• Drafting Committee: WG 1 - TC 62/SC 62C/WG 1
• Current Stage: DELPUB - Deleted Publication
• Start Date: 04-Feb-2025
• Completion Date: 14-Aug-2020

Relations

• Revised: IEC 60601-2-68:2025 - Medical electrical equipment - Part 2-68: Particular requirements for the basic safety and essential performance of X-ray-based image-guided radiotherapy equipment for use with electron accelerators, light ion beam therapy equipment and radionuclide beam therapy equipment
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60601-2-68 ®
Edition 1.0 2014-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Medical electrical equipment –
Part 2-68: Particular requirements for the basic safety and essential performance
of X-ray-based image-guided radiotherapy equipment for use with electron
accelerators, light ion beam therapy equipment and radionuclide beam therapy
equipment
Appareils électromédicaux –
Partie 2-68: Exigences particulières pour la sécurité de base et les performances
essentielles des appareils de radiothérapie à rayonnement X assistée par
imagerie médicale, destinés à être utilisés avec les accélérateurs d’électrons, les
appareils de thérapie par faisceau d’ions légers et les appareils de thérapie par
faisceau de radionucléides
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IEC 60601-2-68 ®
Edition 1.0 2014-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Medical electrical equipment –

Part 2-68: Particular requirements for the basic safety and essential performance

of X-ray-based image-guided radiotherapy equipment for use with electron

accelerators, light ion beam therapy equipment and radionuclide beam therapy

equipment
Appareils électromédicaux –
Partie 2-68: Exigences particulières pour la sécurité de base et les performances

essentielles des appareils de radiothérapie à rayonnement X assistée par

imagerie médicale, destinés à être utilisés avec les accélérateurs d’électrons, les

appareils de thérapie par faisceau d’ions légers et les appareils de thérapie par

faisceau de radionucléides
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XB
ICS 11.040.60 ISBN 978-2-8322-1839-6

– 2 – IEC 60601-2-68:2014 © IEC 2014
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
201.1 Scope, object and related standards . 7
201.2 Normative references . 9
201.3 Terms and definitions. 10
201.4 General requirements . 18
201.5 General requirements for testing ME EQUIPMENT . 19
201.6 Classification of me equipment and me systems . 19
201.7 ME EQUIPMENT identification, marking and documents . 19
201.8 Protection against electrical HAZARDS from ME EQUIPMENT . 25
201.9 Protection against MECHANICAL HAZARDS of ME EQUIPMENT and ME SYSTEMS . 28
201.10 Protection against unwanted and excessive radiation HAZARDS . 32
201.11 Protection against excessive temperatures and other HAZARDS . 34
201.12 Accuracy of controls and instruments and protection against hazardous
outputs . 34
201.13 Hazardous situations and fault conditions for me equipment . 34
201.14 PROGRAMMABLE ELECTRICAL MEDICAL SYSTEMS (PEMS) . 35
201.15 Construction of me equipment. 35
201.16 ME SYSTEMS . 35
201.17 Electromagnetic compatibility of ME EQUIPMENT and ME SYSTEMS . 35
201.101 Reference data for X-IGRT . 36
201.102 X-IGRT IMAGING . 40
201.103 IGRT analysis and correction . 47
203 RADIATION protection in diagnostic X-RAY EQUIPMENT . 51
206 Usability . 52
Annex B (informative) Sequence of testing . 54
Annex I (informative) ME SYSTEMS aspects . 54
Annex AA (informative) Particular guidance and rationale . 55
Annex BB (informative) Measuring CTDI . 57
free air
Bibliography . 58
Index of defined terms used in this standard . 59

Figure 201.101 – PATIENT SUPPORT movements . 53

Table 201.101 – Data required in the technical description . 22
Table 201.102 – Clauses and subclauses in this particular standard that require the
provision of information in the ACCOMPANYING DOCUMENTS, INSTRUCTIONS FOR USE and
the technical description . 23
Table 201.103 – Example test pattern for CTDI
for kV . 45
free air
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL EQUIPMENT –

Part 2-68: Particular requirements for the basic safety and essential
performance of X-ray-based image-guided radiotherapy equipment
for use with electron accelerators, light ion beam therapy equipment
and radionuclide beam therapy equipment

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
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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.
International standard IEC 60601-2-68 has been prepared by IEC subcommittee 62C
Equipment for radiotherapy, nuclear medicine and radiation dosimetry of IEC technical
committee 62: Electrical equipment in medical practice.
The text of this particular standard is based on the following documents:
FDIS Report on voting
62C/595/FDIS 62C/602/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

– 4 – IEC 60601-2-68:2014 © IEC 2014
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.
An asterisk (*) as the first character of a title or at the beginning of a paragraph or table title
indicates that there is guidance or rationale related to that item in Annex AA.
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 publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
Modern RADIOTHERAPY practices utilize information from various imaging modalities, acquired
prior to initiating administration of the therapy, to plan the treatment. The imaging provides
information about the location of the TARGET VOLUME and other anatomical features so that a
treatment plan can be developed that provides an optimal dose distribution to have the best
chance of achieving the intended effect of treatment while minimizing side effects.
However, difficulties arise when trying to administer the RADIATION, since TARGET
VOLUMES/critical structures are constantly moving within the body. For example, in parts of the
body moving with respiration, the TARGET VOLUMES/critical structures may change position or
shape during the RADIATION BEAM delivery throughout any given fraction. Furthermore, a
course of therapy may extend over many days, during which the TARGET VOLUME/PATIENT may
shrink or grow and/or move. Hence, the exact location of the TARGET VOLUME/critical
structures may change between the time of treatment planning imaging and the actual
administration of a treatment.
IMAGE-GUIDED RADIOTHERAPY (IGRT) combines planar or volumetric imaging during the course
of RADIOTHERAPY in order to adjust the treatment delivery based on the PATIENT anatomy and
PATIENT position. This enables the OPERATOR and/or EXTERNAL BEAM EQUIPMENT (EBE) to adjust
the RADIATION BEAM delivery based on the imaging information, such as the position of the
TARGET VOLUME, critical organs and/or other reference features, to compensate for anatomical
changes including internal organ motions and/or treatment setup uncertainties. The increased
accuracy and precision achieved allows higher doses of RADIATION to be delivered to the
TARGET VOLUME and a reduction in the margin of healthy cells affected by the RADIATION. This
is often used in conjunction with other monitoring equipment.
This particular standard establishes requirements to be complied with by MANUFACTURERS in
the design and construction of X-RAY IGRT EQUIPMENT (X-IGRT).
This particular standard covers safety aspects of kilovoltage (kV) and megavoltage (MV) X-ray
imaging devices in a known geometrical relationship with an EXTERNAL BEAM EQUIPMENT such
as an ELECTRON ACCELERATOR, medical light ion beam equipment or RADIONUCLIDE BEAM
THERAPY EQUIPMENT, for the purpose of IGRT. It covers aspects of communication and
relationships between the EXTERNAL BEAM EQUIPMENT and X-ray imaging devices, attached or
not directly attached to but in the same RADIATION shielded area as, and dedicated for use
only with, the EXTERNAL BEAM EQUIPMENT.
This particular standard applies to X-ray based IGRT equipment used in-room for IGRT
purposes. This particular standard does not apply to standard CT scanners, which are not
used for IGRT. However if a CT scanner is used in-room with a linear (electron) accelerator
(linac) for IGRT then this particular standard applies.
When performing a HAZARD ANALYSIS, the MANUFACTURER should consider relevant diagnostic
standards. For example, IMAGE DISPLAY DEVICE quality is specified in IEC documents in
regards to diagnostic use (e.g. IEC 62563-1:2009, Ed. 1.0). However, since IGRT usage may
or may not require such high requirements it is left to the MANUFACTURER to specify what is
required for use with their X-IGRT EQUIPMENT.
This particular standard deals with the safety aspect of image acquisitions, image analysis,
data transfer and treatment replanning or EBE/PATIENT repositioning.
This particular standard deals with equipment for REAL-TIME X-IGRT, ONLINE X-IGRT and OFFLINE
X-IGRT.
X-IGRT EQUIPMENT is also related to the following current standards:
– IEC 62083, Medical electrical equipment – Requirements for the safety of radiotherapy
treatment planning systems
– 6 – IEC 60601-2-68:2014 © IEC 2014
– IEC 61217, Radiotherapy equipment – Coordinates, movements and scales
– IEC 62274, Medical electrical equipment – Safety of radiotherapy record and verify
systems
– IEC 60976, Medical electrical equipment – Medical electron accelerators – Functional
performance characteristics
– IEC TR 60977, Medical electrical equipment – Medical electron accelerators – Guidelines
for functional performance characteristics.
This particular standard may give rise to amendments to some of the above standards.
This particular standard will focus on the safety aspects of the primary function of X-IGRT. It
will not focus on emerging technologies within the field so as to not hinder progress, yet it will
define a safe way of achieving X-IGRT.

MEDICAL ELECTRICAL EQUIPMENT –

Part 2-68: Particular requirements for the basic safety and essential
performance of X-ray-based image-guided radiotherapy equipment
for use with electron accelerators, light ion beam therapy equipment
and radionuclide beam therapy equipment

201.1 Scope, object and related standards
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 X-ray
based IMAGE-GUIDED RADIOTHERAPY equipment for use with EXTERNAL BEAM EQUIPMENT (EBE).
This particular standard covers safety aspects of kilovoltage (kV) and megavoltage (MV) X-ray
imaging devices in a known geometrical relationship with EBE for the purpose of IGRT. It
covers aspects of communication and relationships between the EXTERNAL BEAM EQUIPMENT
and X-ray imaging devices, attached or not directly attached to, but in the same RADIATION
shielded area as, and dedicated for use only with, the EXTERNAL BEAM EQUIPMENT.
This particular standard deals with equipment for REAL-TIME X-IGRT, ONLINE X-IGRT and OFFLINE
X-IGRT. It covers procedures to reduce the risk of over-reliance on the X-IGRT EXTERNAL BEAM
SYSTEM (X-IGRT EBS). For example the manufacturer will provide an interactive interface for
user interaction with the correction suggested by the system.
If a clause or subclause is specifically intended to be applicable to X-IGRT EBE SYSTEMS the
content of that clause or subclause will say so. If that is not the case, the clause or subclause
applies only to X-IGRT EQUIPMENT.
This particular standard, with the inclusion of TYPE TESTS and SITE TESTS, applies respectively
to the MANUFACTURER and some installation aspects of X-IGRT EBE SYSTEMS intended to be
• for NORMAL USE, operated under the authority of appropriately licensed or QUALIFIED
PERSONS by OPERATORS having the required skills for a particular medical application, for
particular specified clinical purposes, e.g. STATIONARY RADIOTHERAPY or MOVING BEAM
,
RADIOTHERAPY
• maintained in accordance with the recommendations given in the INSTRUCTIONS FOR USE,
• subject to regular quality assurance performance and calibration checks by a QUALIFIED
PERSON.
NOTE In this particular standard, all references to installation refer to installation in the RESPONSIBLE
ORGANIZATION’S premises
201.1.2 Object
Replacement:
—————————
The general standard is IEC 60601-1:2005 + IEC 60601-1:2005/AMD1:2012, Medical electrical equipment –
Part 1: General requirements for basic safety and essential performance

– 8 – IEC 60601-2-68:2014 © IEC 2014
The object of this particular standard is to establish particular BASIC SAFETY and ESSENTIAL
PERFORMANCE requirements for X-IGRT EQUIPMENT and X-IGRT EBE SYSTEMS.
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.
IEC60601-1-3 and IEC 60601-1-6 apply as modified in Clause 203 and Clause 206
respectively. IEC 60601-1-8, IEC 60601-1-9, IEC 60601-1-10 and IEC 60601-1-11 do not
apply. All other published collateral standards in the IEC 60601-1 series apply as published.
Collateral standards published after the date of publication of this standard shall only apply
subject to further amendment to this standard.
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 number.
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 particular 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 IEC 60601-1-2 collateral
standard, 203.4 in this particular standard addresses the content of Clause 4 of the
IEC 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 clause or subclause in this particular standard, the clause or
subclause of the general standard or applicable collateral standard, although possibly not
relevant, applies without modification; where it is intended that any part 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
Clause 2 of the general standard applies, except as follows:
Amendment:
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 60601-1-6:2010, Medical electrical equipment – Part 1-6: General requirements for basic
safety and essential performance – Collateral standard: Usability
IEC 60601-1-6:2010/AMD1:2013
Addition:
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic
safety and essential performance
IEC 60601-1:2005/AMD1:2012
IEC 60601-2-1:2009, Medical electrical equipment – Part 2-1: Particular requirements for the
basic safety and essential performance of electron accelerators in the range 1 MeV to 50 MeV
IEC 60601-2-4:2010, Medical electrical equipment – Part 2-4: Particular requirements for the
basic safety and essential performance of cardiac defibrillators
IEC 60601-2-44:2012, Medical electrical equipment – Part 2-44: Particular requirements for
the basic safety and essential performance of X-ray equipment for computed tomography
IEC 60731:2011, Medical electrical equipment – Dosimeters with ionization chambers as used
in radiotherapy
IEC/TR 60788:2004, Medical electrical equipment – Glossary of defined terms
IEC 60976:2007, Medical electrical equipment – Medical electron accelerators – Functional
performance characteristics
IEC 61217:2011, Radiotherapy equipment – Coordinates, movements and scales
IEC 61223-3-5:2004, Evaluation and routine testing in medical imaging departments – Part 3-
5: Acceptance tests – Imaging performance of computed tomography X-ray equipment
IEC 61262-7:1995, Medical electrical equipment – Characteristics of electro-optical X-ray
image intensifiers – Part 7: Determination of the modulation transfer function
IEC 62083:2009, Medical electrical equipment – Requirements for the safety of radiotherapy
treatment planning systems
– 10 – IEC 60601-2-68:2014 © IEC 2014
IEC 62274:2005, Medical electrical equipment – Safety of radiotherapy record and verify
systems
IEC 62366:2007, Medical devices – Application of usability engineering to medical devices
IEC 62396-1:2012, Process management for avionics – Atmospheric radiation effects – Part
1: Accommodation of atmospheric radiation effects via single event effects within avionics
electronic equipment
IEC 62563-1:2009, Medical electrical equipment – Medical image display systems – Part 1:
Evaluation methods
NOTE Informative references are listed in the bibliography beginning on page 58.
201.3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60601-2-1,
IEC 60601-1:2005 + IEC 60601-1:2005 /AMD1:2012, and IEC/TR 60788:2004 apply, except
as follows:
NOTE An index of defined terms is found at the end of the document.
Addition:
201.3.201
COMPUTED TOMOGRAPHY DOSE INDEX 100
CTDI
integral of the DOSE PROFILE representative of a single axial scan along a line perpendicular to
the TOMOGRAPHIC PLANE divided by N × T according to the following:
for N × T less than or equal to 40 mm
+50 mm
D (y)
=  dy
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 (y) free air, N×T
Ref
=  dz ×
CTDI
∫
(N ×T) CTDI
Ref free air, Ref
−50 mm
where:
D(y) is the DOSE PROFILE representative of a single axial scan along a line
perpendicular to the TOMOGRAPHIC PLANE, where dose is reported as
ABSORBED DOSE in air and is evaluated within a polymethylmethacrylate
(PMMA) dosimetry PHANTOM (see 201.102.5.2);
(N × T) is a specific N × T of 20 mm or the largest N x T available not greater
Ref
than 20 mm;
D (y) is the DOSE PROFILE representative of a single axial scan along a line
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 201.102.5.2) for (N × T) ;
Ref
CTDI is the CTDI (201.3.202) for a specific value of N × T;
free air,N × T free air
is the CTDI (201.3.202) for (N × T) ;
CTDI
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 to entry: 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 to entry: This definition assumes that the DOSE PROFILE is centred on y = 0.
Note 3 to entry: A single axial scan is typically a 360° rotation of the X-ray source. For CBCT partial rotations are
still considered as a single axial scan.
Note 4 to entry: When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with a “y-flying FOCAL SPOT” or
with CBCT modes that merge multiple scans, the denominator of the integral needs to be replaced by the total
nominal width along y of overlapping tomographic sections. For example, if the percentage of overlap is 50%, then
the denominator would be replaced by 0,5 x N x T.
Note 5 to entry: Typically the y-axis is the axis of rotation (the y-axis corresponds to the z-axis in the DICOM
coordinate system.)
Note 6 to entry: The CTDI is designed to include most of the scattered RADIATION.
Note 7 to entry: See IEC 60601-2-44:2009/AMD1:2012, Annex CC for more explanation.
Note 8 to entry: It is assumed for MV CBCT that an appropriate calibrated pencil chamber is used.
Note 9 to entry: The note to entry concerning the origin of the abbreviation CTDI applies to the French text only.
[SOURCE: IEC 60601-2-44:2009/AMD1:2012, 201.3.203, modified – Notes 3, 4 and 5 to entry
have been extended, and Note 8 to entry added.]
201.3.202
COMPUTED TOMOGRAPHY DOSE INDEX FREE-IN-AIR
CTDI
free air
integral of the DOSE PROFILE representative of a single axial scan along a line through
ISOCENTRE and perpendicular to the TOMOGRAPHIC PLANE divided by N × T according to the
following
+L/2
D (y)
=  dy
CTDI
free air
∫
N × T
−L/2
where
D(y) is the DOSE PROFILE representative of a single axial scan along a line through
ISOCENTRE and 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;
L is at least (N × T) +40 mm, but not less than 100 mm.
Note 1 to entry: This definition assumes that the DOSE PROFILE is centered on y = 0. The y axis corresponds to the
z axis in the DICOM coordinate system
Note 2 to entry: When the TOMOGRAPHIC SECTIONS overlap, e.g. in CT SCANNERS with a “y-flying FOCAL SPOT” or
with CBCT modes that merges multiple scans, the denominator of the integral needs to be replaced by the total
nominal width along y 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 3 to entry: Typically a RADIATION DETECTOR of length L or longer is used. Annex DD provides an example for
alternate measurements.
Note 4 to entry: For CBCT the imaging is not slice based and N × T is the scan length along a line perpendicular to
the TOMOGRAPHIC PLANE with the NOMINAL collimation.
Note 5 to entry: It is assumed for MV CBCT that an appropriate calibrated pencil chamber or ion chamber, and a
build-up cap is used.
– 12 – IEC 60601-2-68:2014 © IEC 2014
[SOURCE: IEC 60601-2-44:2009/AMD1:2012, 201.3.215, modified – Note 1 and 2 to entry
have been extended and Notes 4 and 5 to entry added.]
201.3.203
CONE BEAM COMPUTED TOMOGRAPHY
CBCT
RADIATION
computed tomography performed using a cone beam of X-
201.3.204
CONTRAST TO NOISE RATIO
CNR
physical quantity describing the ability to distinguish between various contrast objects of a
digital image and the inherent noise within the image, defined as the difference of mean pixel
values of the contrast objects and image background, and divided by the standard deviation
of the image background pixel value
S – S
A B
Note 1 to entry: C =
σ
S and S are signal intensities for the signal producing structures A and B in the region of interest and σ is the
A B 0
standard deviation of the image noise. The MANUFACTURER specifies the structures defining A and B.
Note 2 to entry: The note to entry concerning the origin of the abbreviation CNR applies to the French text only.
[SOURCE: IEC 61223-3-2:2007, 3.8, modified – Two notes to entry have been added.]
201.3.205
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 y-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, adjusted for dynamic collimation modes
if applicable.
Note 1 to entry: L might be longer than the programmed scan length.
Note 2 to entry: The time weighted average of CTDI is to be used if CTDI is variable.
vol vol
Note 3 to entry: A way for obtaining L could be to use the FWHM along a line perpendicular to the
TOMOGRAPHIC PLANE at isocenter of the free-in-air DOSE PROFILE for the entire scan. In the absence of dynamic
collimation this is approximately equivalent to table travel during the entire LOADING.
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.
Note 4 to entry: For CBCT, usually only c) is applicable where N × T is the scan length along a line
perpendicular to the TOMOGRAPHIC PLANE with the NOMINAL collimation.
Note 5 to entry: Typically the y-axis is the axis of rotation. The y axis corresponds to the z axis in the DICOM
coordinate system.
d) For axial scanning without gaps and helical scanning, both involving back-and-forth
PATIENT SUPPORT movement between two positions (shuttle mode)
DLP = CTDI × ((N × T) + R)
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;
R is the distance between the two positions.
Note 6 to entry: The note to entry concerning the origin of the abbreviation DLP applies to the French text
only.
[SOURCE: IEC 60601-2-44:2009/AMD1:2012, 201.3.214, modified – Notes 4 and 5 to entry
have been added.]
201.3.206
DOSE PROFILE
representation of the dose as a function of position along a line
[SOURCE: 60601-2-44:2009/AMD1:2012, 201.3.205]
201.3.207
EXTERNAL BEAM EQUIPMENT
EBE
external RADIATION EQUIPMENT utilizing ELECTRON ACCELERATORS, light ion beam equipment or
RADIONUCLIDE BEAM THERAPY EQUIPMENT
Note 1 to entry: The note to entry concerning the origin of the abbreviation EBE applies to the French text only.
201.3.208
IGRT EQUIPMENT
ME EQUIPMENT that provides IGRT functionality
201.3.209
IMAGE-GUIDED RADIOTHERAPY
IGRT
radiotherapy process by which the location of a radiotherapy beam relative to the intended
TARGET VOLUME within a patient’s anatomy is determined by imaging of the TARGET VOLUME
and surrounding anatomical structures at the time of treatment, so as to enable any
necessary positional corrections to the intended relative location of beam to TARGET VOLUME
Note 1 to entry: The note to entry concerning the origin of the abbreviation IGRT applies to the French text only.
[SOURCE: IEC 60976:2007, 3.8]
– 14 – IEC 60601-2-68:2014 © IEC 2014
201.3.210
IMAGE RECONSTRUCTION
a method to process acquired data into an image data set that can be used for analysis
Note 1 to entry: The analysis of the reconstructed image data set can be for the purpose of IMAGE REGISTRATION
against reference data.
201.3.211
IMAGE REGISTRATION
a method for mapping or registering corresponding points from one image data set to another
Note 1 to entry: IMAGE REGISTRATION can be rigid or deformable.
201.3.212
IMAGING SESSION
the length of continuous time that images are taken of the PATIENT while the PATIENT remains
on the PATIENT positioning device
Note 1 to entry: If the PATIENT is removed from the PATIENT positioning device, the imaging session is ended.
201.3.213
KILOVOLTAGE X-IGRT EQUIPMENT
X-IGRT EQUIPMENT using kilovoltage X-RADIATION
201.3.214
MEGAVOLTAGE X-IGRT EQUIPMENT
X-IGRT EQUIPMENT using megavoltage X RADIATION
201.3.215
MODULATION TRANSFER FUNCTION
MTF
modulus of the generally complex optical transfer function, expressed as a function of SPATIAL
FREQUENCIES u and v
Note 1 to entry: The MTF can be determined in several ways, e.g. from the Fourier transforms of the point spread
function (PSF), the line spread function (LSF) and the edge spread function (ESF). Any method is acceptable if
performed correctly. (Adapted from IEC 61262-7:1995)
Note 2 to entry: The note to entry concerning the origin of the abbreviation MTF applies to the French text only.
[SOURCE: IEC 62220-1:2003, 3.9, modified – A note to entry has been added, and the
symbol for the term has been changed.]
201.3.216
NORMAL USE
operation, including routine inspection and adjustments by any OPERATOR, and STAND-BY,
according to the INSTRUCTIONS FOR USE
Note 1 to entry: NORMAL USE should not be confused with INTENDED USE. While both include the concept of use
as intended by the MANUFACTURER, INTENDED USE focuses on the medical purpose while NORMAL USE incorporates
not only the medical purpose, but maintenance, transport, etc. as well.
Note 2 to entry: NORMAL USE is all functions performed by the OPERATOR. This includes warmup, calibration and
other testing “physics” modes.
[SOURCE: IEC 60601-1:2005/AMD1:2012, definition 3.71, modified – Note 2 has been
added.]
201.3.217
OFFLINE IGRT
IGRT for the purpose of PATIENT setup and/or treatment plan adjustment to be applied in
subsequent treatment delivery
201.3.218
ONLINE IGRT
IGRT for the purpose of PATIENT setup or tr
...