IEC TR 62926:2019
(Main)Medical electrical system - Guidelines for safe integration and operation of adaptive external-beam radiotherapy systems for real-time adaptive radiotherapy
Medical electrical system - Guidelines for safe integration and operation of adaptive external-beam radiotherapy systems for real-time adaptive radiotherapy
IEC TR 62926:2019 provides guidelines for safe integration and operation of an adaptive external-beam RADIOTHERAPY system (AEBRS) for intra-fractionally moving rigid TARGET VOLUMEs, where required equipment can be sourced from one or several MANUFACTURERs. In particular it addresses guidelines to help ensure safe integration and operation for the PATIENT, OPERATOR, other persons and sensitive devices in the vicinity. In this document, the word “system” is hereafter used to refer to an AEBRS.
This document specifies the safety guidelines for a MANUFACTURER or RESPONSIBLE ORGANIZATION who integrates the AEBRS for intra-fractionally moving rigid TARGET VOLUMEs. If a RESPONSIBLE ORGANIZATION integrates an AEBRS, then it takes the role of MANUFACTURER and will be referred to as a MANUFACTURER throughout this document.
This document includes reference models of the AEBRS for intra-fractionally moving rigid TARGET VOLUMEs and HAZARDs which, at a minimum, are considered during the RISK ANALYSIS.
Although TARGET VOLUMES and OARs can deform during motion, adaptations in response to deformations of the TARGET VOLUME are out of the scope of this document. The scope is limited to rigid TARGET VOLUMEs exhibiting intra-fractional movements, both translational and rotational. While technical HAZARDs are discussed in this document, the RESPONSIBLE ORGANIZATION is reminded that clinical judgement is always employed when determining clinical usability and reviewing TREATMENT PARAMETER changes.
This document does not specifically address HAZARD mitigations for each of the HAZARDs mentioned in the document; however, some mitigations are given as examples in Clauses 4 and 5. All guidelines in this document are intended to be implemented in accordance with the general standard IEC 60601-1:2005 and IEC 60601-1:2005/AMD1:2012, with special attention to 4.2 of IEC 60601-1:2005 and IEC 60601-1:2005/AMD1:2012.
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IEC TR 62926 ®
Edition 1.0 2019-05
TECHNICAL
REPORT
colour
inside
Medical electrical system –
Guidelines for safe integration and operation of adaptive external-beam
radiotherapy systems for real-time adaptive radiotherapy
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IEC TR 62926 ®
Edition 1.0 2019-05
TECHNICAL
REPORT
colour
inside
Medical electrical system –
Guidelines for safe integration and operation of adaptive external-beam
radiotherapy systems for real-time adaptive radiotherapy
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 11.040.50 ISBN 978-2-8322-6911-4
– 2 – IEC TR 62926:2019 © IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 9
4 General safety guidelines for an AEBRS for intra-fractionally moving rigid TARGET
VOLUMEs . 12
4.1 TARGET VOLUMEs addressed in this document . 12
4.2 Relationship between system configuration of an AEBRS, existing standards,
and this document. 13
4.2.1 General . 13
4.2.2 Representative configurations of AEBRSs, their relationships to existing
standards, and this document . 13
4.2.3 Representative AEBRS reference models . 16
4.3 RISK MANAGEMENT of an AEBRS . 17
4.3.1 General . 17
4.3.2 RISK ANALYSIS of an AEBRS . 18
4.3.3 RISK EVALUATION . 18
4.3.4 RISK control . 18
4.3.5 Evaluation of overall RESIDUAL RISK acceptability . 18
4.3.6 RISK MANAGEMENT report . 19
4.3.7 Examples of RISK MANAGEMENT of an AEBRS . 19
5 Guidance for design elements that should be considered for safe integration of an
AEBRS for intra-fractionally moving TARGET VOLUMEs . 19
5.1 General . 19
5.2 Specific guidelines for an AEBRS . 20
5.2.1 Configuration of the AEBRS . 20
5.2.2 INTERLOCKs . 20
5.2.3 Coordinate system . 21
5.2.4 Communication between pieces of equipment. 21
5.2.5 Interactions between MDE, MCF and EBE . 22
5.2.6 Status check of each piece of equipment . 23
5.2.7 Failure state judgement . 23
5.2.8 LATENCY related to an AEBRS. 23
5.2.9 Typical verification items of the AEBRS . 25
5.2.10 Validation of AEBRS . 25
5.3 Specific guidelines for the MOTION COORDINATION FUNCTION . 25
5.3.1 PREDICTION MODEL. 25
5.3.2 Gating and tracking . 25
Annex A (informative) A minimum set of HAZARDs to consider for adaptive TREATMENT
functions . 27
A.1 Overview. 27
A.2 Reference design for adaptive TREATMENT functionality . 27
A.3 Overview of HAZARDOUS SITUATIONS . 28
Annex B (informative) An example of RISK ANALYSIS for an AEBRS with gating function
using X-RAY FLUOROSCOPE as an MDE . 32
B.1 Configuration of the example AEBRS . 32
B.2 PROCESS overview . 32
B.3 HAZARDOUS SITUATIONS and RISK fishbone diagram . 33
B.4 Failure Mode and Effect Analysis (FMEA) . 33
B.5 RISK ANALYSIS. 37
Annex C (informative) An example of RISK ANALYSIS for an AEBRS with tracking
using two different MDEs . 38
function
C.1 Configuration of the example AEBRS . 38
C.2 Failure Mode and Effect Analysis (FMEA) . 38
Annex D (informative) Dynamic phantom for validation tests . 42
D.1 Necessity of a dynamic phantom . 42
D.2 Guidelines for a simple dynamic phantom . 42
D.3 Example of dosimetric validation test using the dynamic phantom . 42
Bibliography . 44
Index of defined terms . 46
Figure 1 – Concept of AEBRS with information flow . 7
Figure 2 – Example of system configuration . 7
Figure 3 – AEBRS incorporating an MDE addressed by particular standards . 14
Figure 4 – AEBRS incorporating an MDE not addressed by a particular standard . 14
Figure 5 – AEBRS incorporating an MDE with an interface to an MCF . 14
Figure 6 – AEBRS incorporating an MCF with an interface to an EBE . 14
Figure 7 – AEBRS with a gating interface between an MCF and an EBE . 15
Figure 8 – Functions and information flow of an AEBRS . 15
Figure 9 – BEAM GATING system for intra-fractionally moving rigid TARGET VOLUMEs . 16
Figure 10 – Beam tracking system for intra-fractionally moving rigid TARGET VOLUMEs . 17
Figure A.1 – Functional decomposition of adaptive TREATMENT control for gating and
tracking functionality in the AEBRS . 28
Figure B.1 – Risk fishbone diagram for an AEBRS . 33
Figure B.2 – Tables for RISK ANALYSIS . 37
Figure D.1 – Sketch of a simple dynamic phantom . 43
Table B.1 – Failure Mode and Effect Analysis (FMEA) for an AEBRS using fluoroscope
as a MDE, gating function as an MCF, and proton beam therapy machine as an EBE . 34
Table C.1 – Failure Mode and Effect Analysis (FMEA) for an AEBRS with tracking
function as an MCF, and Infrared (IR) camera as MDE 1, x-ray fluoroscope as MDE 2,
MEDICAL ELECTRON ACCELERATOR as EBE . 39
and
– 4 – IEC TR 62926:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL SYSTEM –
GUIDELINES FOR SAFE INTEGRATION AND OPERATION OF ADAPTIVE
EXTERNAL-BEAM RADIOTHERAPY SYSTEMS FOR REAL-TIME ADAPTIVE
RADIOTHERAPY
FOREWORD
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IEC TR 62926, which is a technical report, has been prepared by subcommittee 62C:
Equipment for radiotherapy, nuclear medicine and radiation dosimetry, of IEC technical
committee 62: Electrical equipment in medical practice.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
62C/729/DTR 62C/737/RVDTR
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
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contents. Users should therefore print this document using a colour printer.
– 6 – IEC TR 62926:2019 © IEC 2019
INTRODUCTION
Recent developments in RADIOTHERAPY using EXTERNAL BEAM EQUIPMENT (EBE) allow the
delivery of doses to TARGET VOLUMEs with greater precision and accuracy than before, while
also sparing surrounding critical structures to a higher degree. Three-dimensional or four-
dimensional volumetric images are increasingly being used as PATIENT ANATOMY MODELs in
RADIOTHERAPY TREATMENT PLANNING SYSTEMs (RTPSs) when simulating a dose distribution. The
intended dose distribution is achievable when the four-dimensional location and shape of the
TARGET VOLUME and organs at RISK (OARs) during TREATMENT match those of the TARGET
VOLUME and OARs at the time of TREATMENT PLANNING. PATIENT anatomy and related
physiology are subject to continuous changes as may result from respiration, cardiac motion,
and digestive motion, both in the short and long term perspective during RADIOTHERAPY. These
include changes in position, orientation, and deformation of the TARGET VOLUME.
Consideration for changes in anatomy or physiology during the course of RADIOTHERAPY, as
well as during each fraction, is an important issue in modern RADIOTHERAPY. For example, lung
tumours can exhibit translational and rotational changes which may result in underdosage of
the TARGET VOLUME and overdosage of OARs. Techniques have been developed to reduce these
RISKS by adapting the TREATMENT to the tumour as it moves in real-time. This can be achieved by
instructing the EBE to perform a BEAM HOLD during translational motion of the TARGET VOLUME, by
repositioning the PATIENT using a robotic PATIENT POSITIONER, by tilting or moving the RADIATION HEAD,
by dynamically adapting the MULTILEAF COLLIMATORs (MLCs) of the EBE, or by changing the scanning
field of LIGHT ION BEAM equipment operating in scanning mode.
During delivery of ADAPTIVE RADIOTHERAPY, the PATIENT anatomy or physiology is monitored
and changes to TREATMENT PARAMETERS are allowed throughout the course of TREATMENT
based upon the monitored information (see definition of ADAPTIVE RADIOTHERAPY). ADAPTIVE
RADIOTHERAPY is increasingly being used to assure delivery of the prescribed ABSORBED DOSE
distribution during intra-fractional changes of TARGET VOLUMEs. There are many different types
of MOTION DETECTION EQUIPMENT (MDE) used to monitor intra-fractional organ changes. Some
of these use imaging techniques, e.g. X-RAY BASED IMAGE-GUIDED RADIOTHERAPY, ULTRASOUND
EQUIPMENT, and MAGNETIC RESONANCE EQUIPMENT, while others use surrogate parameters.
Examples of equipment that use surrogate parameters include air flow meters, STRAIN GAUGEs,
infrared sensors, optical surface mapping devices, and magnetic field sensors. In some cases,
multiple MDEs are combined with a single EBE to monitor intra-fraction motion of multiple
organs.
When ADAPTIVE RADIOTHERAPY includes intra-fraction monitoring of the TARGET VOLUME
position and shape using an MDE, coordination between the MDE and the EBE is crucial to
apply TREATMENT PARAMETER changes at the correct time. A MOTION COORDINATION FUNCTION
(MCF) ensures that information about position and shape is appropriately linked to the
TREATMENT PLAN, selects TREATMENT PARAMETERS, and sends ADAPTATION INSTRUCTIONs to the
EBE. Integration and operation of the MDE, EBE, and MCF is essential to perform ADAPTIVE
RADIOTHERAPY safely for a PATIENT with an intra-fractionally changing TARGET VOLUME. There
are many possible combinations of EBEs, MDEs and MCFs. Each one can function
independently or be integrated as a part of another. Because each function could be an
independent piece of MEDICAL ELECTRICAL EQUIPMENT (MEE) and since the safety discussed in
this document depends upon the safe integration and operation of the EBEs, MDEs, and MCFs,
this combination will be dealt with as a MEDICAL ELECTRICAL SYSTEM. An adaptive external-
beam RADIOTHERAPY system (AEBRS) consists of these three main pieces of equipment and
respective functions.
The MCF part of an AEBRS can be software or a PROGRAMMABLE ELECTRICAL MEDICAL SYSTEM,
and should be subject to the requirements of IEC 62304 or IEC 60601-1. The MDE can be
components or systems which are not necessarily compliant with IEC 60601-1.
The reader’s attention is drawn to ASTM F-2761 (a publication of the American Society for
Testing and Materials) which describes an integrated clinical environment (ICE). The general
requirements and the conceptual model of an ICE are described in F-2761. This document
uses similar concepts and presents guidance for AEBRS RISK MANAGEMENT.
The reader’s attention is also drawn to RADIATION PROTECTION N° 181 which contains
general guidelines on RISK MANAGEMENT in external beam radiotherapy.
The concept of an AEBRS with representative information flow is shown in Figure 1.
Figure 1 – Concept of AEBRS with information flow
This document provides guidelines for the safe integration and operation of an AEBRS for
REAL-TIME ADAPTIVE RADIOTHERAPY. Since real-time monitoring of deformations of TARGET
VOLUMEs is still a work-in-progress at this moment, this document addresses rigid TARGET
VOLUMEs exhibiting intra-fractional translations and rotations. Deformations of TARGET
VOLUMEs are not considered.
This document covers systems, whose configuration may be represented by Figure 2, where
potential use of multiple MDEs in one AEBRS is reflected.
Figure 2 – Example of system configuration
Some EQUIPMENT for image or data acquisition and motion coordination is not covered by
existing standards. Therefore, there are safety aspects that arise from the integration of
EQUIPMENT into an AEBRS that should be considered and that are not addressed by
various
existing standards. Based on the considerations discussed above, guidelines should be
developed to mitigate the RISKs arising from the integration and operation of ME EQUIPMENT
and other various equipment (including non-ME EQUIPMENT) into an AEBRS, as shown in
Figures 1 and 2.
– 8 – IEC TR 62926:2019 © IEC 2019
This document discusses potential RISKs to be considered during the RISK ANALYSIS and
provides recommendations for the safe integration and operation of an AEBRS. Since not all
equipment may have an IEC/ISO standard, or an existing standard may not cover the use of
the equipment as part of an AEBRS, this document also provides guidelines for individual
pieces of EQUIPMENT that are part of the AEBRS. These guidelines are meant to enhance and
not supersede requirements that may already exist.
Regarding existing standards, IEC 60601-2-68 includes requirements for X-ray-based MDE in
an AEBRS. Requirements and recommendations in IEC 60601-2-68 are often applicable to an
AEBRS where the MDE is other than an X-ray-based imaging device, such as optical,
ULTRASOUND, or MAGNETIC RESONANCE IMAGING devices. For example, requirements
addressing protection against electrical, mechanical, and RADIATION HAZARDs, or requirements
X-IGRT LATENCY, which is the time between initiation of image acquisition to
addressing
delivery of the output signal by an MDE, are also applicable to non X-ray-based imaging
devices. MANUFACTURERS or RESPONSIBLE ORGANIZATIONs who integrate an AEBRS for intra-
fractionally moving rigid TARGET VOLUMEs should use IEC 60601-2-68 as guidance even when
they utilize non X-ray-based imaging devices as MDE in the AEBRS.
Finally, this document addresses safety issues of the AEBRS without assuming specific
RESPONSIBLE
clinical procedures. As with any testing within a clinical environment, the
ORGANIZATION should consider its clinical workflows and practices when devising tests for its
facility.
MEDICAL ELECTRICAL SYSTEM –
GUIDELINES FOR SAFE INTEGRATION AND OPERATION OF ADAPTIVE
EXTERNAL-BEAM RADIOTHERAPY SYSTEMS FOR REAL-TIME ADAPTIVE
RADIOTHERAPY
1 Scope
This document provides guidelines for safe integration and operation of an adaptive external-
RADIOTHERAPY system (AEBRS) for intra-fractionally moving rigid TARGET VOLUMEs,
beam
where required equipment can be sourced from one or several MANUFACTURERs. In particular it
addresses guidelines to help ensure safe integration and operation for the PATIENT, OPERATOR,
other persons and sensitive devices in the vicinity. In this document, the word “system” is
hereafter used to refer to an AEBRS.
This document specifies the safety guidelines for a MANUFACTURER or RESPONSIBLE
who integrates the AEBRS for intra-fractionally moving rigid TARGET VOLUMEs. If
ORGANIZATION
a RESPONSIBLE ORGANIZATION integrates an AEBRS, then it takes the role of MANUFACTURER
and will be referred to as a MANUFACTURER throughout this document.
This document includes reference models of the AEBRS for intra-fractionally moving rigid
TARGET VOLUMEs and HAZARDs which, at a minimum, are considered during the RISK ANALYSIS.
Although TARGET VOLUMES and OARs can deform during motion, adaptations in response to
TARGET VOLUME are out of the scope of this document. The scope is
deformations of the
limited to rigid TARGET VOLUMEs exhibiting intra-fractional movements, both translational and
rotational. While technical HAZARDs are discussed in this document, the RESPONSIBLE
ORGANIZATION is reminded that clinical judgement is always employed when determining
clinical usability and reviewing TREATMENT PARAMETER changes.
This document does not specifically address HAZARD mitigations for each of the HAZARDs
mentioned in the document; however, some mitigations are given as examples in Clauses 4
and 5. All guidelines in this document are intended to be implemented in accordance with the
general standard IEC 60601-1:2005 and IEC 60601-1:2005/AMD1:2012, with special attention
to 4.2 of IEC 60601-1:2005 and IEC 60601-1:2005/AMD1:2012.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic safety
and essential performance
IEC 60601-1:2005/AMD1:2012
ISO 14971:2007, Medical devices – Application of risk management to medical devices
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
– 10 – IEC TR 62926:2019 © IEC 2019
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
ADAPTATION INSTRUCTION
instruction generated for TREATMENT PARAMETER ADAPTATION
3.2
ADAPTIVE RADIOTHERAPY
radiotherapy that monitors PATIENT anatomy or physiology and, based upon the monitored
information, allows changes to TREATMENT PARAMETERs throughout the course of treatment
Note to entry: IMAGE GUIDED RADIATION THERAPY (IGRT) is one form of ADAPTIVE RADIOTHERAPY.
3.3
BEAM GATING
allowance or inhibition of IRRADIATION and related equipment movements according to the
status provided by a BEAM GATING SIGNAL
[SOURCE: IEC 60601-2-64:2014, 201.3.204]
3.4
BEAM GATING SIGNAL
BEAM GATING
signal generated for the purpose of
EXAMPLE Examples include a respiratory spirometer, electrocardiogram, optical sensor, etc.
[SOURCE: IEC 60601-2-64:2014, 201.3.205]
3.5
BEAM HOLD
condition during IRRADIATION in which the MEE has minimized the TREATMENT IRRADIATION
output (approximating the IRRADIATION off condition)
NOTE 1 TO ENTRY: BEAM HOLD is not the same as INTERRUPTION OF IRRADIATION where the MEE is changed to the
beam off state
NOTE 2 TO ENTRY: BEAM HOLD is a subcondition of IRRADIATION for the purpose of rapid transition to intended
TREATMENT IRRADIATION output
Note 3 to entry: This is commonly used during gating, IMRT, etc.
[SOURCE: IEC 60601-2-1:20─, 201.3.208]
3.6
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
[SOURCE: IEC 60601-2-68:2014, 201.3.207]
3.7
IRRADIATION
exposing of a living being or matter to RADIATION
Note 1 to entry: In RADIOLOGY, exposing of a living being or matter to IONIZING RADIATION.
Note 2 to entry: Examples of ionizing radiation include: x-rays, gamma-rays, electrons, neutrons, and light ions.
[SOURCE: IEC TR 60788:2004, rm-12-09, modified – moved examples of IONIZING RADIATION
to a note.]
3.8
LATENCY
time interval between initiation of an event and its effect
[SOURCE: IEC 60601-2-1:20─, 201.3.232]
3.9
MANUFACTURER
natural or legal person with responsibility for the design, manufacture, packaging, or labelling
of ME EQUIPMENT, assembling an ME SYSTEM, or adapting ME EQUIPMENT or an ME SYSTEM,
regardless of whether these operations are performed by that person or on that person's
behalf by a third party
Note 1 to entry: ISO 13485 defines “labelling” as written, printed or graphic matter
– affixed to a medical device or any of its containers or wrappers, or
– accompanying a medical device,
related to identification, technical description, and use of the medical device, but excluding shipping documents. In
this standard, that material is described as markings and ACCOMPANYING DOCUMENTS.
Note 2 to entry: “Adapting” includes making substantial modifications to ME EQUIPMENT or an ME SYSTEM already
in use.
Note 3 to entry: In some jurisdictions, the RESPONSIBLE ORGANIZATION can be considered a MANUFACTURER when
involved in the activities described.
Note 4 to entry: Adapted from ISO 14971:2007, definition 2.8.
[SOURCE: IEC 60601-1:2005 and IEC 60601-1:2005/AMD1:2012, 3.55]
3.10
MOTION COORDINATION FUNCTION
MCF
function that evaluates and combines information provided by one or more MDEs to derive and
adapt TREATMENT PARAMETERS
Note 1 to entry: The MCF can include a PREDICTION MODEL, a function generating ADAPTATION INSTRUCTIONS and a
function for evaluating validity and deliverability of the ADAPTATION INSTRUCTIONs.
3.11
MOTION DETECTION EQUIPMENT
MDE
equipment that acquires data for monitoring changes in PATIENT anatomy or physiology
Note 1 to entry: This includes changes in position, orientation and deformation of the TARGET VOLUME, and
changes in PATIENT setup or surface positioning.
3.12
MULTILEAF COLLIMATOR
MLC
a multi-element BLD capable of defining RADIATION FIELDS of irregular shapes
Note 1 to entry: The positions of the individual elements can either be static or can be changed dynamically
during IRRADIATION.
[SOURCE: IEC 60601-2-1:20─, 201.3.233]
– 12 – IEC TR 62926:2019 © IEC 2019
3.13
PREDICTION MODEL
algorithm that predicts changes, such as changes in PATIENT anatomy or physiology, based on
information from one or more MDEs
Note 1 to entry: This includes predicting changes in position, orientation and deformation of the TARGET VOLUME.
3.14
RADIATION HEAD
structure from which the RADIATION BEAM emerges
[SOURCE: IEC TR 60788:2004, rm-20-06]
3.15
REAL-TIME ADAPTIVE RADIOTHERAPY
radiotherapy that, throughout therapeutic IRRADIATION, monitors PATIENT anatomy or
physiology and based upon that information, allows autonomous adjustments of TREATMENT
PARAMETERs throughout the therapeutic IRRADIATION without OPERATOR intervention
3.16
TREATMENT PARAMETER ADAPTATION
change of TREATMENT PARAMETERS based on monitored changes, such as changes in PATIENT
anatomy or physiology
Note 1 to entry: BEAM GATING and tracking are examples of TREATMENT PARAMETER ADAPTATION.
3.17
X-IGRT LATENCY
time from initiation of image acquisition to delivery of output signal by X-IGRT EQUIPMENT to the
EBE
Note 1 to entry: It is expected that the EBE should also state its LATENCY time from receiving a signal to providing
the requested action.
Note 2 to entry: The X-IGRT LATENCY includes the hardware and software LATENCIES.
Note 3 to entry: Network transfer times vary from one installation to another as there are too many factors
involved that are supplied by the user. Network transfer LATENCY therefore is not considered as part of the X-IGRT
LATENCY time.
[SOURCE: IEC 60601-2-68:2014, 201.3.234, modified – In Note 1 to entry, "correction" was
replaced by "requested action".]
4 General safety guidelines for an AEBRS for intra-fractionally moving rigid
TARGET VOLUMEs
4.1 TARGET VOLUMEs addressed in this document
The effects of intra-fraction TARGET VOLUME translations, rotations and deformations on
delivered dose distributions depend not only on the extent of these changes but also on the
size and shape of the TARGET VOLUME and on changes in the surrounding tissues. For
example, the dose distribution for a rotated small spheroid shaped target (e.g. a baseball
shape) will not change much as the rotation angle increases, while the dose distribution can
change significantly for a rotated long narrow cylinder target (e.g. a cigar shape) if rotated
perpendicularly to its long axis.
The detection of TARGET VOLUME translations, rotations and deformations during the delivery
of a single fraction is difficult without real-time volumetric imaging techniques. However,
TARGET VOLUME changes can be predicted by combining 4D volumetric planning images with
information from associated surrogate detectors such as orthogonal 2D imaging with
implanted fiducial markers, spirometers, expansion belts, or PATIENT surface scanning
EQUIPMENT. Monitoring of deformations by volumetric imaging in real-time is still considered a
work-in-progress at this moment. Therefore, it will not be addressed in this document.
The RESPONSIBLE ORGANIZATION should investigate the effects of translations, rotations and
deformations and the clinical tolerances allowed for their PATIENT population and select the
appropriate combination of sensors, software and other MEES. This document addresses
safety issues associated with integrating these combinations but does not address the clinical
applications.
4.2 Relationship between system configuration of an AEBRS, existing standards, and
this document
4.2.1 General
The RISK arising from the integration of equipment in an AEBRS should be addressed by the
MANUFACTURER and this should be done according to existing STANDARDs, where available.
Irrespective of the system configuration of an AEBRS, IEC 60601-1 and its collaterals always
apply. Particular standards may exist to cover equipment integrated in an AEBRS. Examples
of such particular standards are IEC 60601-2-1 and IEC 60601-2-64 for EBE, IEC 60601-2-68
MCF or a combination of MCF and MDE, and IEC 60601-2-33 and IEC 60601-2-44 for MDE.
for
This document provides further guidance in implementing 4.2 and Clause 14 from IEC 60601-
1:2005 and IEC 60601-1:2005/AMD1:2012.
The MANUFACTURER of an AEBRS should ask the MANUFACTURER of any MEE to be integrated to
provide applicable conditions of interoperability and requirements for acceptability.
Mitigation of AEBRS RISKS is the responsibility of the integrating party, and the mitigation
should be demonstrated by a completed Test Report Form for the IEC 60601-1 series of
standards.
Compliance of the AEBRS can be documented by referencing the corresponding clauses or
subclauses of existing standard(s) for the integrated devices.
NOTE 1 An example of MEEs covered by particular standards in the IEC 60601 series is illustrated when assessing
the RISK associated with an AEBRS using LIGHT ION BEAM equipment as an EBE and utilizing X-ray RADIOSCOPY as
an MDE. IEC 60601-2-64:2014 applies to the EBE and IEC 60601-2-68:2014 applies to the MDE and MCF.
NOTE 2 An example of an MEE not covered by IEC 60601 particular standards is illustrated when assessing the
RISK associated with an AEBRS utilizing a 3D camera as MDE. The latter is not addressed by any of the standards
in the IEC 60601-1 series.
Annexes A to C show examples of RISK MANAGEMENT of an AEBRSs as explained in 4.3.2.
4.2.2 Representative configurations of AEBRSs, their relationships to existing
standards, and this document
4.2.2.1 General
Representative configurations of AEBRSs, their relationships to existing standards and this
document are described in the following subclauses. The dotted line in each figure indicates
the function or EQUIPMENT covered by the standard cited in each of the following paragraphs
and figures. This document covers the entire system as described by the series of examples.
4.2.2.2 Relationship with standards for MOTION DETECTION EQUIPMENT (MDE)
Figure 3 shows an example of an AEBRS incorporating MDE that are addressed by particular
standards (e.g. IEC 60601-2-33 for MRI, IEC 60601-2-68 for X-IGRT).
– 14 – IEC TR 62926:2019 © IEC 2019
Figure 3 – AEBRS incorporating an MDE addressed by particular standards
Figure 4 shows an example of an AEBRS incorporating MDE (e.g. surface guided MOTION
DETECTION EQUIPMENT) which is not addressed by a particular standard.
Figure 4 – AEBRS incorporating an MDE not addressed by a particular standard
4.2.2.3 Relationship with STANDARDs for MDE with an interface to MCF
An example of MDE with an interface to an MCF is shown in Figure 5. The figure shows an
example of X-IGRT EQUIPMENT that incorporates an MCF. The particular standard addressing X-
IGRT is IEC 60601-2-68.
Figure 5 – AEBRS incorporating an MDE with an interface to an MCF
4.2.2.4 Relationship with STANDARDs for EBE with an interface to an MCF
An example of an EBE with an interface to an MCF is shown in Figure 6. The figure shows an
ELECTRON ACCELERATOR or a LIGHT ION BEAM ME EQUIPMENT which is interfaced to an MCF. The
standard addressing ELECTRON ACCELERATOR equipment is IEC 60601-2-1, and the standard
addressing LIGHT ION BEAM ME EQUIPMENT is IEC 60601-2-64.
Figure 6 – AEBRS incorporating an MCF with an interface to an EBE
4.2.2.5 Relationship with the guideline for an interface between an MCF and an EBE
The interface between an MCF and an EBE is shown in Figure 7. The figure shows an example
of a gating interface. An existing guideline addressing a gating interface is NEMA RT-1.
Figure 7 – AEBRS with a gating interface between an MCF and an EBE
4.2.2.6 A generic reference model of an AEBRS for intra-fractionally moving rigid
TARGET VOLUMEs with information flow for a representative system
An adaptive external-beam RADIOTHERAPY system (AEBRS) for intra-fractionally moving rigid
TARGET VOLUMEs is defined as consisting of an EXTERNAL BEAM EQUIPMENT (EBE), a MOTION
DETECTION EQUIPMENT (MDE), and MOTION COORDINATION FUNCTIONs (MCFs). MDEs acquire data
TARGET VOLUME or an appropriate
for monitoring the intra-fractional movement of the rigid
surrogate; an MCF performs the TREATMENT PARAMETER ADAPTATION according to the
information provided by the MDE and sends ADAPTATION INSTRUCTIONs to the EBE; and the EBE
delivers a TREATMENT to the PATIENT accordingly. Figure 1 shows the concept of the AEBRS
and the information flow. A representative system configuration of an AEBRS is shown in
Figure 2. In Figure 8, functions and information flow are shown using the representative
Figure 2.
system configuration of
Figure 8 – Functions and information flow of an AEBRS
The AEBRS may incorporate multiple pieces of MOTION DETECTION EQUIPMENT (MDE). MDEs
acquire data for monitoring the intra-fractional movement of the rigid TARGET VOLUME or an
appropriate surrogate, which can be used to estimate the position of the TARGET VOLUME in
three dimensions, registering both translations and rotations. This positional information is
MCF. Deformations of the TARGET VOLUME are not covered in this document.
processed by the
An MCF includes a PREDICTION MODEL, a function generating ADAPTATION INSTRUCTIONs, and a
function for evaluating the validity and deliverability of the ADAPTATION INSTRUCTIONs. The MCF
– 16 – IEC TR 62926:2019 © IEC 2019
may evaluate and combine information from multiple MDEs. The selected ADAPTATION
INSTRUCTIONs are sent to the EBE.
The PREDICTION MODEL predicts the changes in rotational and translational position of the rigid
TARGET VOLUME based on information from the MDE, and prior information generated by the
PREDICTION MODEL.
The results of the prediction by the PREDICTION MODEL are used to generate ADAPTATION
INSTRUCTIONs.
The validity and deliverability of the generated ADAPTATION INSTRUCTIONs are evaluated.
ADAPTATION INSTRUCTIONs valid for TREATMENT PARAMETER ADAPTATION are selected and sent
to the EBE for TREATMENT delivery.
The EBE executes TREATMENT delivery by applying the new TREATMENT PARAMETERs according
ADAPTATION INSTRUCTIONs output by the MCF.
to the
4.2.3 Representative AEBRS reference models
4.2.3.1 General
The function performed by the MCF of the AEBRS can be classified as a gating function or a
tracking function. These are described in Figure 9 and Figure 10 respectively.
4.2.3.2 BEAM GATING system model
EAM GATING system for intra-fractionally moving rigid TARGET VOLUMEs
Figure 9 – B
Figure 9 shows an example of an AEBRS reference model; a BEAM GATING system for intra-
fractionally moving rigid TARGET VOLUMEs. The configuration parameters describing the
relationship between the location of internal fiducial markers and the rigid TARGET VOLUME at
each respiratory phase is loaded into the MCF before the treatment. Orthogonal 2D imaging of
internal fiducial markers is used as an MDE and the 3D position of a fiducial marker is
MDE to the MCF. In the MCF, a PREDICTION MODEL predicts the changes in
transferred from the
position of the rigid TARGET VOLUME based on information from the MDE. The output of the
PREDICTION MODEL is used to generate ADAPTATION INSTRUCTIONs, which are BEAM GATING
SIGNALs in this case. After evaluation of the generated BEAM GATING SI
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