SIST EN ISO 16645:2019
(Main)Radiological protection - Medical electron accelerators - Requirements and recommendations for shielding design and evaluation (ISO 16645:2016)
Radiological protection - Medical electron accelerators - Requirements and recommendations for shielding design and evaluation (ISO 16645:2016)
ISO 16645:2016 is applicable to medical electron linear accelerators i.e. linear accelerators with nominal energies of the beam ranging from 4 MV to 30 MV, including particular installations such as robotic arm, helical intensity modulated radiotherapy devices and dedicated devices for intra operative radiotherapy (IORT) with electrons.
The cyclotrons and the synchrotrons used for hadrontherapy are not considered.
The radiation protection requirements and recommendations given in ISO 16645:2016 cover the aspects relating to regulations, shielding design goals and other design criteria, role of the manufacturers, of the radiation protection officer or qualified expert and interactions between stakeholders, radiations around a linear accelerator, shielding for conventional and special devices (including shielding materials and transmission values, calculations for various treatment room configurations, duct impact on radiation protection) and the radiological monitoring (measurements).
Strahlenschutz - Medizinische Elektronenbeschleuniger-Anlagen - Anforderungen und Empfehlungen an die Ausführung der Abschirmung und deren Bewertung (ISO 16645:2016)
Diese Internationale Norm gilt für medizinische lineare Elektronenbeschleuniger, d. h. lineare Beschleuniger mit Nennstrahlenergien von 4 MV bis 30 MV einschließlich spezieller Installationen wie robotergestützter Geräte, helikaler fluenzmodulierter Strahlentherapiegeräte und spezieller Geräte für die intraoperative Strahlentherapie (IORT) mit Elektronen.
Für die Hadrontherapie eingesetzte Zyklotrone und Synchrotrone werden nicht berücksichtigt.
Die Strahlenschutzanforderungen und -empfehlungen in dieser Internationalen Norm behandeln die Aspekte in Bezug auf Verordnungen, die Ziele der Abschirmungsgestaltung und anderer Gestaltungskriterien, die Rolle der Hersteller, des Strahlungsschutzbeauftragten oder qualifizierten Experten und die Interaktionen zwischen Stakeholdern, Strahlungen im Umfeld eines linearen Beschleunigers, die Abschirmungen für konventionelle und spezielle Geräte (einschließlich Abschirmungsmaterialien und Übertragungswerte, Berechnungen für verschiedene Behandlungsraumkonfigurationen, die Auswirkung von Kanälen auf den Strahlenschutz) und die radiologische Überwachung (Messungen).
ANMERKUNG 1 Anhang A enthält Übertragungswerte für die häufigsten Abschirmungsmaterialien.
ANMERKUNG 2 Anhang B enthält unterstützende Daten für die Berechnung der Abschirmung.
ANMERKUNG 3 Anhang C enthält ein Beispiel für die Berechnung konventioneller Geräte und eines Standard-Labyrinths.
Radioprotection - Accélérateurs médicaux d'électrons - Exigences et recommandations pour la conception et l'évaluation du blindage (ISO 16645:2016)
L'ISO 16645:2016 s'applique aux accélérateurs linéaires d'électrons médicaux, c'est-à-dire aux accélérateurs linéaires avec des énergies nominales de faisceau dans la gamme de 4 MV à 30 MV, y compris les installations particulières telles que le bras robotisé, les appareils de radiothérapie hélicoïdale avec modulation d'intensité et les appareils dédiés à la radiothérapie peropératoire (IORT) avec électrons.
Les cyclotrons et les synchrotrons utilisés pour l'hadronthérapie ne sont pas considérés.
Les exigences et recommandations en matière de radioprotection données dans l'ISO 16645:2016 couvrent les aspects liés aux réglementations, aux objectifs de conception de la protection radiologique et autres critères de conception, au rôle des fabricants, de la personne compétente en radioprotection ou de l'expert qualifié et aux interactions entre les parties prenantes, aux rayonnements autour d'un accélérateur linéaire, à la protection pour les appareils conventionnels et spéciaux (y compris les matériaux de protection et les valeurs de transmission, les calculs pour différentes configurations de salle de traitement, l'impact des conduits sur la radioprotection) et à la surveillance radiologique (mesurages).
NOTE 1 L'Annexe A procure des valeurs de transmission pour les matériaux de protection les plus courants.
NOTE 2 L'Annexe B fournit des données servant au calcul de la protection radiologique.
NOTE 3 L'Annexe C donne un exemple de calcul pour un appareil conventionnel et une chicane standard.
Radiološka zaščita - Medicinski elektronski pospeševalniki - Zahteve in priporočila za snovanje in ocenjevanje zaščitnih zaslonov (ISO 16645:2016)
Standard ISO 16645:2016 se uporablja za medicinske elektronske linearne pospeševalnike, tj. linearne pospeševalnike z nominalnimi energijami žarka od 4 MV do 30 MV, vključno s posebnimi instalacijami, kot so robotska roka, radioterapevtske naprave, ki so modulirane s spiralno intenziteto, in naprave, namenjene za medoperacijsko radioterapijo (IORT) z elektroni.
Ciklotroni in sinhrotroni, ki se uporabljajo pri hadronski terapiji, niso upoštevani v tem dokumentu.
Zahteve in priporočila za radiološko zaščito, ki so podani v standardu ISO 16645:2016, obravnavajo vidike, povezane s predpisi, cilji snovanja zaščitnih zaslonov in drugih kriterijev snovanja, vlogo izdelovalcev, pooblaščenega izvedenca varstva pred sevanji ali usposobljenega strokovnjaka ter interakcijami med deležniki, sevanjem okoli linearnega pospeševalnika, zaščito za konvencionalne in posebne naprave (vključno z zaščitnimi materiali in vrednostmi transmisije, izračuni za različne konfiguracije ambulant, vpliv cevi na radiološko zaščito) ter nadzorom sevanja (meritve).
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2019
Radiološka zaščita - Medicinski elektronski pospeševalniki - Zahteve in priporočila
za snovanje in ocenjevanje zaščitnih zaslonov (ISO 16645:2016)
Radiological protection - Medical electron accelerators - Requirements and
recommendations for shielding design and evaluation (ISO 16645:2016)
Strahlenschutz - Medizinische Elektronenbeschleuniger-Anlagen - Anforderungen und
Empfehlungen an die Ausführung der Abschirmung und deren Bewertung (ISO
16645:2016)
Radioprotection - Accélérateurs médicaux d'électrons - Exigences et recommandations
pour la conception et l'évaluation du blindage (ISO 16645:2016)
Ta slovenski standard je istoveten z: EN ISO 16645:2019
ICS:
11.040.99 Druga medicinska oprema Other medical equipment
13.280 Varstvo pred sevanjem Radiation protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 16645
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2019
EUROPÄISCHE NORM
ICS 13.280
English Version
Radiological protection - Medical electron accelerators -
Requirements and recommendations for shielding design
and evaluation (ISO 16645:2016)
Radioprotection - Accélérateurs médicaux d'électrons - Strahlenschutz - Medizinische
Exigences et recommandations pour la conception et Elektronenbeschleuniger-Anlagen - Anforderungen
l'évaluation du blindage (ISO 16645:2016) und Empfehlungen an die Ausführung der
Abschirmung und deren Bewertung (ISO 16645:2016)
This European Standard was approved by CEN on 8 March 2019.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16645:2019 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
The text of ISO 16645:2016 has been prepared by Technical Committee ISO/TC 85 "Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 16645:2019 by Technical Committee CEN/TC 430 “Nuclear
energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by December 2019, and conflicting national standards
shall be withdrawn at the latest by December 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 16645:2016 has been approved by CEN as EN ISO 16645:2019 without any modification.
INTERNATIONAL ISO
STANDARD 16645
First edition
2016-10-01
Corrected version
2016-11-15
Radiological protection — Medical
electron accelerators — Requirements
and recommendations for shielding
design and evaluation
Radioprotection — Accélérateurs médicaux d’électrons — Exigences
et recommandations pour la conception et l’évaluation du blindage
Reference number
ISO 16645:2016(E)
©
ISO 2016
ISO 16645:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
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ii © ISO 2016 – All rights reserved
ISO 16645:2016(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Quantities . 1
3.2 Definitions . 4
4 Shielding design goals and other design criteria . 6
4.1 Shielding design goals. 6
4.2 Shielding design assumptions . 7
5 Role of the manufacturers, of the radiation protection officer or qualified expert
and interactions between stakeholders . 8
5.1 General . 8
5.2 Linear accelerator manufacturer . 8
5.3 Shielding material vendor . 9
5.4 Architectural firm/general contractor .10
5.5 Radiation protection officer or qualified expert .10
5.6 The licensee .11
6 Radiation fields around a linear electron accelerator .11
6.1 General .11
6.2 X-ray radiation .11
6.2.1 Primary X-ray beam .11
6.2.2 Primary electron beam bremsstrahlung .12
6.2.3 Secondary X-ray radiation .12
6.2.4 Tertiary X-ray radiation.13
6.3 Neutron radiation .13
6.3.1 General.13
6.3.2 Direct neutron radiation .14
6.3.3 Scattered and thermal neutron radiation.14
6.3.4 Primary barrier neutron radiation .15
6.4 γ radiation .15
6.4.1 General.15
6.4.2 Maze γ radiation . .15
6.4.3 Door γ radiation.15
6.4.4 Primary barrier γ radiation .15
6.4.5 Air γ radiation .16
7 Shielding materials and transmission values .16
8 General formalism for shielding calculation .18
9 Shielding calculation for conventional devices .20
9.1 General .20
9.2 Primary barriers .20
9.2.1 Radiation components .20
9.2.2 Barrier with a unique material .21
9.2.3 Barrier with multiple layers . .21
9.3 Secondary barriers .22
9.3.1 Radiation components .22
9.3.2 Barrier with a unique material .23
9.3.3 Barriers with multiple layers .24
10 Doors and mazes .24
10.1 General .24
ISO 16645:2016(E)
10.2 Radiation components .25
10.3 Standard maze .25
10.3.1 Maze X-ray scatter calculations .25
10.3.2 X-ray direct Leakage . . .30
10.3.3 Maze neutron and capture gamma calculations .31
10.4 Two legged maze .33
10.5 No maze - Direct-shielded doors .34
10.5.1 General.34
10.5.2 Shielding at the far side of a direct-shielded door entrance .35
10.5.3 Shielding at the near side of a direct-shielded door entrance .37
10.6 No door at maze entrance .39
10.7 Door Calculations .40
10.7.1 General.40
10.7.2 Maze door calculations .40
10.7.3 Direct Shielded Door Calculations .41
11 Shielding calculations for special devices .41
11.1 General .41
11.2 Robotic arm accelerator .41
11.3 Helical intensity modulated radiotherapy .42
11.4 Dedicated device for intra operative radiotherapy with electrons .42
12 Ducts .43
12.1 Duct impact on radiation protection .43
12.2 Recommended location and geometry .43
12.3 Additional shielding .44
12.3.1 General.44
12.3.2 Neutron and capture gamma radiation passing through the interior of the
shielded duct .44
12.3.3 X scattered radiation passing through the interior of the shielded duct .45
12.3.4 Scattered radiation passing through the walls of the duct shielding .46
12.3.5 Dose equivalent at HVAC duct exterior opening .46
13 Special considerations .46
13.1 Skyshine .46
13.1.1 General.46
13.1.2 X-ray skyshine radiation .46
13.1.3 Neutron skyshine radiation .48
13.2 Groundshine radiations .49
13.3 Joints and junctions .49
14 Shielding evaluation (experimental verification) .49
14.1 General .49
14.2 Measuring equipment and methodology .50
14.3 Evaluation .50
15 Indication, warning signs, interlocks .52
Annex A (informative) Tenth value layers for the most common shielding materials .53
Annex B (informative) Supporting data for shielding calculations .66
Annex C (informative) Example of calculation for conventional device and standard maze .68
Bibliography .75
iv © ISO 2016 – All rights reserved
ISO 16645:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT), see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 85, Nuclear energy, nuclear technologies, and
radiological protection, Subcommittee SC 2, Radiological protection.
This corrected version of ISO 16645:2016 incorporates the correction of Tables A.9 and C.6.
ISO 16645:2016(E)
Introduction
Radiotherapy uses external beam radiation to kill cancer cells and shrink tumours. The use of electron
linear accelerators to administer external beam radiation has spread during recent decades and is now
common throughout the world. These accelerators deliver high energy electron and photon beams with
increasingly high dose rates. Although the use of radiotherapy is well established, irradiation techniques
have continued to evolve and are becoming increasingly complex. Examples include modulation of beam
intensity, availability of high dose rate modes, arctherapy, helical intensity modulated radiotherapy,
robotic arm accelerators, and dedicated devices for intra-operative radiotherapy. The shielding design
of treatment rooms has been evolving with these changes. The higher radiation workload associated
with most of these techniques can impact the shielding materials used. The irradiation technique can
also impact the geometry to be considered in the shielding calculations.
IEC 60601-2-1 relates to the design and the construction of the accelerators in order to ensure the
[1] [2][3]
safety of their operation . In addition, several national or international (IAEA Safety Reports
Series Report No. 47, 2006) reports propose recommendations concerning the installation and the
exploitation of these accelerators, the safety devices, the design and the calculation of protections, the
[4]
radiological control and monitoring. National standards have been established in certain countries
[5]
. Moreover national regulations impose particular rules of protection against radiation, in particular
relating to the definition of the controlled areas and the calculation of shielding.
Taking into account the developments of new irradiation techniques and of new designs of treatment
room facilities on the one hand, and the variety of guides or normative documents on the other hand,
it appeared judicious to establish an international standard to be used as a general framework. This
standard is intended to be complementary to the other international standards (IEC and IAEA).
The following items are discussed in the standard:
— types of accelerators: conventional accelerators with and without flattening filter (FF and FFF
operating modes), devices for helical intensity modulated radiotherapy and robotic arm accelerator,
dedicated machines for intra-operative radiotherapy;
— radiation fields: electrons, X photons and neutrons (direct, scattered, leakage), neutron capture
gamma rays;
— Treatment room geometry: maze without and with door, no maze with direct door;
— materials of protection: concrete (ordinary or high density), metals, laminated barriers (concrete
and metal), hydrogenated materials, earth and others;
— design of the radiotherapy facility:
— calculation methods of the shielding, including neutrons, various types of installations and shielding
geometries;
— evaluation of the impact of the maze and calculation of the protection of the entrance door;
— evaluation of the impact of the ducts (ventilation and air-conditioning, high voltage and fluids) and
additional protections;
— shielding design assumption and goals;
— Radiation survey of the completed installation to ensure national requirements have been met and
the shielding and design is fit for purpose after installation of the accelerator.
vi © ISO 2016 – All rights reserved
INTERNATIONAL STANDARD ISO 16645:2016(E)
Radiological protection — Medical electron accelerators —
Requirements and recommendations for shielding design
and evaluation
1 Scope
This International Standard is applicable to medical electron linear accelerators i.e. linear accelerators
with nominal energies of the beam ranging from 4 MV to 30 MV, including particular installations
such as robotic arm, helical intensity modulated radiotherapy devices and dedicated devices for intra
operative radiotherapy (IORT) with electrons.
The cyclotrons and the synchrotrons used for hadrontherapy are not considered.
The radiation protection requirements and recommendations given in this International Standard
cover the aspects relating to regulations, shielding design goals and other design criteria, role of
the manufacturers, of the radiation protection officer or qualified expert and interactions between
stakeholders, radiations around a linear accelerator, shielding for conventional and special devices
(including shielding materials and transmission values, calculations for various treatment room
configurations, duct impact on radiation protection) and the radiological monitoring (measurements).
NOTE 1 Annex A provides transmission values for the most common shielding materials.
NOTE 2 Annex B provides supporting data for shielding calculation.
NOTE 3 Annex C provides an example of calculation for conventional device and standard maze.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
IEC 60976, Medical electrical equipment — Medical electron accelerators — Functional performance
characteristics
IAEA Safety Reports Series Report No. 47, Radiation protection in the Design of Radiotherapy
Facilities (2006)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60976 and the following apply.
3.1 Quantities
3.1.1
absorbed dose
D
quotient of dε by dm, where dε is the mean energy imparted to matter of mass dm thus
dε
D =
dm
ISO 16645:2016(E)
Note 1 to entry: In this document, the absorbed dose is defined for radiation produced by a linear accelerator at a
specific location: the absorbed dose to water at the isocentre (at 1 m from the source for conventional devices) at a
reference depth in water in electron equilibrium conditions (for example at the depth of maximum absorbed dose).
−1
Note 2 to entry: The unit of absorbed dose is joule per kilogram (J·kg ), and its special name is gray (Gy).
[6]
[SOURCE: ISO 12749-2:2013, 4.1.6.7]
3.1.2
absorbed dose rate
output rate
DR
o
dose absorbed per unit of time
Note 1 to entry: In this International Standard, in the absence of specific indication, the absorbed dose rate is
defined for radiation produced by a linear accelerator at a specific location: the absorbed dose rate to water at the
isocentre (at 1 m from the source for conventional devices) at a reference depth in water in electron equilibrium
conditions (for example at the depth of maximum absorbed dose).
−1
Note 2 to entry: The unit of absorbed dose rate is gray per second (Gy·s ). The usual unit for medical accelerators
−1
is gray per hour (Gy·h ).
3.1.3
dose equivalent
H
product of D and Q at a point in tissue, where D is the absorbed dose (3.1.1) and Q is the quality factor
for the specific radiation at this point, thus: H = D × Q
−1
Note 1 to entry: The unit of dose equivalent is joule per kilogram (J·kg ), and its special name is sievert (Sv).
[6]
[SOURCE: ISO 12749-2:2013, 4.1.6.8]
3.1.4
IMRT ratio
C
I
ratio of the average monitor unit per unit prescribed absorbed dose needed for IMRT (MU ) and the
IMRT
monitor unit per unit absorbed dose for conventional treatment (MU )
conv
MU
IMRT
C =
I
MU
CONV
3.1.5
instantaneous dose-equivalent rate
IDR
–1
“ambient/personal” dose-equivalent rate (Sv·h ) as measured with the linear accelerator operating at
–1
the absorbed dose rate DR (Gy·h )
o
Note 1 to entry: This is the direct reading of the ratemeter that gives a stable reading in dose-equivalent per hour.
IDR is specified at a reference point (30 cm) beyond the penetrated barrier.
3.1.6
effective dose
E
summation of all the tissue equivalent doses, each multiplied by the appropriate tissue weighting factor
3.1.7
occupancy factor
T
fraction of time the areas adjacent to the treatment room are occupied by an individual or group during
linear accelerator operation
2 © ISO 2016 – All rights reserved
ISO 16645:2016(E)
3.1.8
orientation or use factor
U
fraction of the time during which the radiation under consideration is directed at a particular barrier
3.1.9
reflection coefficient
α
fraction of radiation (e.g., fluence, energy fluence) expressed by the ratio of the amount backscattered
to that incident
3.1.10
shielding design goal
P
practical values of dose equivalent, for a single radiotherapy source or set of sources, evaluated at a
reference point beyond a protective barrier
Note 1 to entry: The shielding design goals ensure that the respective annual values for effective dose limit
defined by national regulation or IAEA/ICRP for controlled and uncontrolled areas are not exceeded.
3.1.11
(patient) scatter fraction
a(θ)
ratio of absorbed dose at 1 m from a tissue-equivalent scattering object to the absorbed dose measured
at the isocentre with the object removed
Note 1 to entry: This quantity is a function of the scatter angle (θ), incident beam quality, and beam area. A
scattering phantom is typically a water-equivalent volume representing a standard human being.
3.1.12
tenth-value distance
TVD
distance that a specified radiation travels under broad beam condition in order to reduce the radiation
field intensity to one-tenth of its original value
3.1.13
tenth-value layer
TVL
thickness of a specific material that reduces a specified radiation field intensity by a factor of 10 of its
original value, under broad beam condition
Note 1 to entry: TVL is expressed in m or cm of a defined material or in kg/m (thickness × density).
Note 2 to entry: TVL and TVL are the first and the second tenth-value layer thicknesses, respectively.
1 2
Note 3 to entry: TVL is the equilibrium tenth-value layer, thickness for each subsequent tenth-value layer in the
e
region in which the directional and spectral distributions of the radiation field are practically independent of
thickness.
Note 4 to entry: TVL is the cumulative tenth-value layer, approximate value based on large attenuation
c
measurements: for a given thickness t, TVL = -t/log(B).
c
3.1.14
time averaged dose-equivalent rate
TADR
barrier attenuated dose-equivalent rate averaged over a specified period of accelerator operation
Note 1 to entry: TADR is proportional to instantaneous dose-equivalent rate (IDR), and depends on the values of
workload (W) and orientation or use factor (U).
ISO 16645:2016(E)
3.1.15
transmission factor (or barrier transmission)
B
ratio of radiation field intensity at a location behind the barrier on which radiation is incident to the field
intensity at the same location without the presence of the shield, for a given radiation type and quality
Note 1 to entry: B is a measure of the shielding effectiveness of the barrier.
3.1.16
workload
W
average absorbed dose to water of radiation produced by a linear accelerator, at the isocentre at a
reference depth in water in electron equilibrium conditions, over a specified period averaged over a year
Note 1 to entry: The workload is specified in Gray (Gy).
Note 2 to entry: The time period should be consistent between shielding design goals and workload.
Note 3 to entry: The isocentre is at 1 m from the source for conventional devices.
Note 4 to entry: The reference depth in water is for example the depth of maximum absorbed dose.
3.2 Definitions
3.2.1
barrier (or protective barrier)
protective wall of radiation attenuating material(s) used to reduce the dose equivalent on the side
beyond the radiation source to an acceptable level compatible with national legislation or international
guidance
3.2.2
primary barrier
wall, ceiling, floor or other structure designed to attenuate the direct radiation emitted from the target
or source that passes though the collimator opening (useful beam) to an acceptable level compatible
with national legislation or international guidance
3.2.3
secondary barrier
wall, ceiling, floor or other structure not struck by the primary beam and designed to attenuate
the leakage and scattered radiations to an acceptable level compatible with national legislation or
international guidance
3.2.4
controlled area
defined area in which specific protection measures and safety provisions are or could be required for
controlling exposures or preventing the spread of contamination in normal working conditions, and
preventing or limiting the likelihood and magnitude of potential exposures
Note 1 to entry: This implies that access, occupancy, and working conditions are controlled for radiation
protection purposes.
[7]
[SOURCE: IAEA BSS]
3.2.5
geometrical field size
geometrical projection as seen from the centre of the front surface of the radiation source on a plane
perpendicular to the axis of the beam of the distal end of the beam limiting device or collimator
Note 1 to entry: The field is thus of the same shape as the aperture of the beam limiting device.
Note 2 to entry: The projected field size is specified at a particular distance from the target, e.g. at the isocentre
1 m from the target or at the reference distance of the device.
4 © ISO 2016 – All rights reserved
ISO 16645:2016(E)
[SOURCE: IEC 60976:2007]
3.2.6
helical intensity modulated radiotherapy
radiotherapy using a linear accelerator that delivers treatment with a slit beam adjustable by a multileaf
collimator (MLC) and that rotates continuously around patient with geometry resembling diagnostic
computed tomography (CT), with concomitant motion of the couch
Note 1 to entry: Helical intensity modulated radiotherapy is often called tomotherapy.
3.2.7
intensity-modulated radiation therapy
IMRT
treatment procedure requiring, in general, the coordinated control of photon or electron fluence, beam
orientation relative to the patient, and beam size, either in a continuous or a discrete manner, and as
pre-determined by a treatment plan
Note 1 to entry: The primary purpose of IMRT is to improve the conformity of the dose distribution to the planned
target volume, while minimizing dose to surrounding healthy tissue.
[SOURCE: IEC 60976:2007]
3.2.8
isocentre
point defined by intersection of the gantry axis of rotation and the beam centerline of a linear accelerator
Note 1 to entry: For conventional linear accelerator, the isocentre is located at 1 m from the radiation source.
3.2.9
leakage radiation
radiation, except the useful beam, coming from the accelerator head and other beam-line components
[1]
Note 1 to entry: It is attenuated by shielding in the treatment head as specified by IEC 60601–2-1 .
3.2.10
members of the public
persons who are not occupationally exposed by a source or practice under consideration
Note 1 to entry: When being irradiated as a result of medical care, patients are not considered as members of
the public.
3.2.11
nominal energy
energy stated by the manufacturer to characterize the radiation beam
Note 1 to entry: “MV” is used when referring to accelerating voltages and the end point energy of a bremsstrahlung
spectrum, while “MeV” is used when referring to monoenergetic photons or electrons
[SOURCE: IEC 60976:2007]
3.2.12
occupied area
room or other space, indoors or outdoors, that is likely to be occupied by any person, either regularly or
periodically during the course of the person’s work, habitation or recreation, and in which an ionizing
radiation field exists because of radiation sources in the vicinity
3.2.13
radiation protection officer
person technically competent in radiation protection matters relevant for a given type of practice who
is designated by the registrant, licensee or employer to oversee the application of relevant requirements
[7]
[SOURCE: IAEA BSS]
ISO 16645:2016(E)
3.2.14
qualified expert
individual who, by virtue of certification by appropriate boards or societies, professional licence or
academic qualifications and experience, is duly recognized as having expertise in a relevant field of
specialization, e.g. medical physics, radiation protection, occupational health, fire safety, quality
management or any relevant engineering or safety specialty
[7]
[SOURCE: IAEA BSS]
3.2.15
robotic arm accelerator
device composed by a linear accelerator mounted on a 6D robotic arm allowing a multi-directional
delivery of the dose
Note 1 to entry: The robotic arm is referred to as 6 degrees of freedom because movements are made for 3
translational motions (X, Y and Z) and 3 rotational motions.
Note 2 to entry: The “geometric isocentre” is a reference point in the room that serves as the origin for several
coordinates systems related to robot and imaging calibration.
3.2.16
scattered radiation
radiation that, during passage through matter, is changed in direction, and the change is usually
accompanied by a decrease in energy and intensity
3.2.17
secondary radiation
radiation produced by scattering from the areas struck by the primary X-ray beam or leakage radiation
through the treatment head of the linear accelerator
3.2.18
supervised area
defined area in which specific protection measures and safety provisions are or could be required for
controlling normal exposures during normal working conditions, and preventing or limiting the extent
of potential exposures
3.2.19
tertiary radiation
radiation produced by scattering from areas struck by leakage radiation, secondary radiation and
primary electron beam bremsstrahlung
4 Shielding design goals and other design criteria
4.1 Shielding design goals
Shielding design goals (P) are levels of dose equivalent (H) used in the design calculations and
evaluation of barriers constructed for the protection of workers or members of the public. Different
shielding design goals shall be defined for supervised, controlled and public areas. They have to be in
accordance with existing national regulation or if not available according to IAEA basic safety standards
on radiation protection related to effective dose limits for workers and members of the public.
The P value (Sv) set by national authorities shoul
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