ISO 12749-4:2015

Nuclear energy, nuclear technologies, and radiological protection — Vocabulary — Part 4: Dosimetry for radiation processing

ISO 12749-4:2015 lists unambiguous terms and definitions for concepts for dosimetry related to radiation processing using gamma radiation, X-radiation, or accelerated electrons. It is intended to facilitate communication and promote common understanding.

Energie nucleaire, technologies nucleaires, et pmtection radiologique — Vocabulaire — Partie 4: Dosimetrie pour processue de radiation

General Information

• Status: Published
• Publication Date: 10-Aug-2015
• ICS: 01.040.13 - Environment. Health protection. Safety (Vocabularies)
• ICS: 13.280 - Radiation protection
• Technical Committee: ISO/TC 85 - Nuclear energy, nuclear technologies, and radiological protection
• Drafting Committee: ISO/TC 85 - Nuclear energy, nuclear technologies, and radiological protection
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 10-Dec-2020

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 12749-4
First edition
2015-08-15
Nuclear energy, nuclear technologies,
and radiological protection —
Vocabulary —
Part 4:
Dosimetry for radiation processing
Energie nucleaire, technologies nucleaires, et pmtection
radiologique — Vocabulaire —
Partie 4: Dosimetrie pour processue de radiation
Reference number
ISO 12749-4:2015(E)
©
ISO 2015

---------------------- Page: 1 ----------------------
ISO 12749-4:2015(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, 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
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2015 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 12749-4:2015(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Structure of the vocabulary . 1
3 Terms and definitions . 1
3.1 Terms related to dosimetry, dosimetry systems and ionizing radiation . 2
3.2 Terms related to dosimeters . 5
3.3 Terms related to radiation processing . 9
3.4 Terms related to measurement .15
Annex A (informative) Methodology used in the development of the vocabulary .19
Bibliography .25
Alphabetical Index .26
© ISO 2015 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 12749-4:2015(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 (see 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 (see 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/TC85 Nuclear energy, nuclear technologies, and
radiological protection.
ISO 12749 consists of the following parts, under the general title Nuclear energy, nuclear technologies,
and radiological protection — Vocabulary:
— Part 2: Radiological protection
— Part 3: Nuclear fuel cycle
— Part 4: Dosimetry for radiation processing
The following part is under preparation:
— Part 5: Nuclear reactors
The following part is planned:
— Part 1: General terminology
iv © ISO 2015 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 12749-4:2015(E)

Introduction
This part of ISO 12749 provides terms and definitions for concepts for dosimetry related to radiation
processing using gamma radiation, X-radiation, or accelerated electrons. Concepts related to the
calibration and use of dosimetry systems for operational qualification and performance qualification
of commercial radiation processing facilities and for dose monitoring for quality assurance during the
routine processing of products are defined. Terminological data are taken from the ISO/ASTM standards
developed by ISO TC 85 and ASTM International Committee E61. Care is taken to ensure definitions are
consistent with other technically validated documents such as VIM, ICRU and GUM.
Unambiguous communication of nuclear energy concepts is crucial since serious consequences can arise
from misunderstandings with regard to standards related to equipment and materials used in nuclear
energy activities. Concepts dealing with dosimetry related to radiation processing and procedures for
preparation, testing, and using dosimetry systems to determine the absorbed dose are present in all
of the ISO/ASTM standards developed by WG3. To avoid misunderstandings, these concepts need to be
designated by common terms and described by harmonized definitions.
Conceptual arrangement of terms and definitions is based on concepts systems that show corresponding
relationships among nuclear energy concepts. Such arrangement provides users with a structured view
of the nuclear energy sector and will facilitate common understanding of all related concepts. Besides,
concepts systems and conceptual arrangement of terminological data will be helpful to any kind of user
because it will promote clear, accurate and useful communication.
© ISO 2015 – All rights reserved v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 12749-4:2015(E)
Nuclear energy, nuclear technologies, and radiological
protection — Vocabulary —
Part 4:
Dosimetry for radiation processing
1 Scope
This part of ISO 12749 lists unambiguous terms and definitions for concepts for dosimetry related to
radiation processing using gamma radiation, X-radiation, or accelerated electrons. It is intended to
facilitate communication and promote common understanding.
2 Structure of the vocabulary
The terminology entries are presented in the conceptual order of the English preferred terms. Both a
systematic index and an alphabetical index are included at the end of the standard. The structure of
each entry is in accordance with ISO 10241-1.
All the terms included in this part of ISO 12749 deal exclusively with dosimetry for radiation processing.
When selecting terms and definitions, special care has been taken to include the terms that need to
be defined, it means, either because the definitions are essential to the correct understanding of the
corresponding concepts or because some specific ambiguities need to be addressed.
The notes appended to certain definitions offer clarification or examples to facilitate understanding of
the concepts described. In certain cases, miscellaneous information is also included, for example, the
units in which a quantity is normally measured, recommended parameter values, references, etc.
According to the title, the vocabulary deals with concepts belonging to the general nuclear energy field
within which concepts in the dosimetry for radiation processing subfield are taking into account.
nuclear energy
dosimetry for radiation
processing
3.1 3.4
3.2  3.3
Terms related to
Terms related to dosimetry, Terms related to Terms related to
dosimetry systems, and measurement
dosimeters radiation processing
ionization radiation facilities
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
© ISO 2015 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO 12749-4:2015(E)

3.1 Terms related to dosimetry, dosimetry systems and ionizing radiation
3.1.1
dosimetry
measurement of absorbed dose by the use of a dosimetry system
[SOURCE: ISO/ASTM 52628:2013, 3.1.7]
3.1.2
absorbed dose
D
quotient of the dε by the dm, where the dε is the mean energy imparted by ionization radiation to
matter of mass dm
Note 1 to entry: It is expressed as
Dm=dε /d
Note 2 to entry: The special name for the unit of absorbed dose is gray (Gy), where 1 gray is equivalent to the
absorption of 1 J per kilogram of a specified material (1 Gy = 1 J / kg).
[SOURCE: ICRU 85a, 5.2.5, October 2011, modified]
Note 3 to entry: In most radiation processing applications, absorbed dose is in terms of absorbed dose to water.
3.1.3
dosimetry system
used for measuring absorbed dose, consisting of dosimeters, measurement instruments and their
associated reference standards, and procedures for the system’s use
[SOURCE: ISO/ASTM 52628:2013, 3.1.8, modified]
3.1.3.1
primary standard dosimetry system
designated or widely acknowledged as having the highest metrological qualities and whose value is
accepted without reference to other standards of the same quantity
[SOURCE: ISO/ASTM 52628:2013, 3.1.11, modified]
3.1.3.2
reference standard dosimetry system
generally having the highest metrological quality available at a given location or in a given organization,
from which measurements made there are derived
[SOURCE: ISO/ASTM 52628:2013, 3.1.13, modified]
3.1.3.3
routine dosimetry system
calibrated against a reference standard dosimetry system and used for routine absorbed dose
measurements, including dose mapping and process monitoring
[SOURCE: ISO/ASTM 52628:2013, 3.1.16, modified]
3.1.3.4
transfer standard dosimetry system
used as an intermediary to calibrate other dosimetry systems, usually routine dosimetry system
[SOURCE: ISO/ASTM 52628:2013, 3.1.18, modified]
2 © ISO 2015 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 12749-4:2015(E)

3.1.4
ionizing radiation
consists of charged particles or uncharged particles, or both, that as a result of physical interaction,
creates ions by primary or secondary processes
Note 1 to entry: Charged particles could be positrons or electrons, and uncharged particles could be X-radiation
or gamma radiation.
[SOURCE: ASTM E170, 14a, modified]
3.1.4.1
gamma radiation
electromagnetic radiation emitted in the process of nuclear transition
[SOURCE: IEC 60050, modified]
3.1.4.1.1
activity
A
quotient of −dN by dt, where dN is the mean change in the number of nuclei in that energy state due to
spontaneous nuclear transformations in the time interval dt
Note 1 to entry: Activity of an amount of radionuclide in a particular energy state at a given time.
Note 2 to entry: It is expressed as
A = −dN/dt
−1 10
Note 3 to entry: The special name for the unit of activity is becquerel (Bq), where 1 Bq = 1 s and 1 Ci = 3,7×10
Bq.
[SOURCE: ICRU 85a, 6.2, October 2011, modified]
3.1.4.1.2
decay constant
λ
quotient of dN/N by dt, where dN/N is the mean fractional change in the number of nuclei in that energy
state due to spontaneous nuclear transformations in the time interval dt
Note 1 to entry: Decay constant of a radionuclide in a particular energy state.
Note 2 to entry: It is expressed as
dN/ N
λ =-
dt
[SOURCE: ICRU 85a, 6.1, October 2011, modified]
3.1.4.1.3
half-life
T
1/2
time taken for the activity of an amount of radionuclide to become half its initial value
Note 1 to entry: Half-life of a radionuclide in a particular energy state.
Note 2 to entry: T = ln2/λ, where λ is the decay constant (3.1.4.1.2).
1/2
© ISO 2015 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO 12749-4:2015(E)

3.1.4.2
X-radiation
X-ray
ionizing electromagnetic radiation, which includes both bremsstrahlung and the characteristic
radiation emitted when atomic electrons make transitions to more tightly bound states
Note 1 to entry: In radiation processing applications, the principal X-radiation is bremsstrahlung.
[SOURCE: ISO/ASTM 51608:2015, 3.2.1]
3.1.4.2.1
bremsstrahlung
broad-spectrum electromagnetic radiation emitted when an energetic charged particle is influenced by
a strong electric or magnetic field, such as that in the vicinity of an atomic nucleus
[SOURCE: ISO/ASTM 51608:2015, 3.1.4]
3.1.4.3
electron beam
stream of electrons generated by an electron accelerator
3.1.5
calibration
set of operations that establish, under specified conditions, the relationship between values of
quantities indicated by a measuring instrument or measuring system, or values represented by a
material measure or a reference material, and the corresponding values realized by standards
[SOURCE: ISO/ASTM 52628:2013, 3.1.3]
3.1.5.1
approved laboratory
recognized national metrology institute; or has been formally accredited to ISO/IEC 17025; or has a
quality system consistent with the requirements of ISO/IEC 17025
Note 1 to entry: A recognized national metrology institute or other calibration laboratory accredited to
ISO/IEC 17025 should be used in order to ensure traceability to a national or international standard. A calibration
certificate provided by a laboratory not having formal recognition or accreditation will not necessarily be proof
of traceability to a national or international standard.
[SOURCE: ISO/ASTM 51261:2013, 3.1.1, modified]
3.1.5.1.1
accredited dosimetry calibration laboratory
dosimetry laboratory with formal recognition by an accrediting organization that the dosimetry
laboratory is competent to carry out specific activities which lead to the calibration or calibration
verification of dosimetry systems in accordance with documented requirements of the accrediting
organization
[SOURCE: ISO/ASTM 52628:2013, 3.1.2]
3.1.5.2
reference standard radiation field
calibrated radiation field, generally having the highest metrological quality available at a given location
or in a given organization, from which measurements made there are derived
[SOURCE: ISO/ASTM 52628:2013, 3.1.14]
4 © ISO 2015 – All rights reserved

---------------------- Page: 9 ----------------------
ISO 12749-4:2015(E)

3.1.5.3
charged-particle equilibrium
electron equilibrium
condition in which the kinetic energy of charged particles, excluding rest mass, entering an infinitesimal
volume of the irradiated material equals the kinetic energy of charge particles emerging from it
Note 1 to entry: This is referred to as electron equilibrium in the case of electrons set in motion by photon
irradiation of a material.
[SOURCE: ISO/ASTM 51261:2013, 3.1.4]
3.1.6
calibration curve
expression of the relation between indication and corresponding measured quantity value
Note 1 to entry: In radiation processing standards, term “dosimeter response” is generally used for “indication”.
[SOURCE: VIM:2008, 4.31]
3.1.7
verification
provision of objective evidence that a given item fulfils specified requirements
[SOURCE: VIM: 2008, 2.44]
3.2 Terms related to dosimeters
3.2.1
dosimeter
device that, when irradiated, exhibits a quantifiable change that can be related to absorbed dose in a
given material using appropriate measurement instruments and procedures
[SOURCE: ISO/ASTM 52628:2013, 3.1.4]
3.2.2
dosimeter batch
quantity of dosimeters made from a specific mass of material with uniform composition, fabricated in
a single production run under controlled, consistent conditions and having a unique identification code
[SOURCE: ISO/ASTM 51276:2012, 3.1.3]
3.2.2.1
dosimeter stock
part of a dosimeter batch held by the user
[SOURCE: ISO/ASTM 51276:2012, 3.1.5]
3.2.3
dosimeter set
one or more dosimeters used to measure the absorbed dose at a location and whose average reading is
used to determine absorbed dose at that location
[SOURCE: ISO/ASTM 51940:2013, 3.1.9]
3.2.4
dosimeter response
reproducible, quantifiable effect produced in the dosimeter by ionizing radiation
Note 1 to entry: The response value may be obtained from such measurements as optical absorbance, thickness,
mass, peak-to-peak distance in EPR spectra, or electropotential between solutions and thermoluminescent
output.
© ISO 2015 – All rights reserved 5

---------------------- Page: 10 ----------------------
ISO 12749-4:2015(E)

[SOURCE: ISO/ASTM 51276:2012, 3.1.4]
3.2.4.1
radiation chemical yield
G(x)
quotient of n(x) by ε , where n(x) is the mean amount of substance of that entity produced, destroyed,
or changed in a system by the mean energy imparted, ε to the matter of that system
Note 1 to entry: Radiation of chemical yield of an entity x.
Note 2 to entry: It is expressed as
G(x) = n(x)/ε
−1
Note 3 to entry: SI unit: mol · J
[SOURCE: ICRU-85a, October 2011, 4.6, modified]
3.2.5
influence quantity
quantity that, in a direct measurement, does not affect the quantity that is actually measured, but
affects the relation between the indication and the measurement result
[SOURCE: VIM:2008, 2.52]
Note 1 to entry: In radiation processing dosimetry, this term includes temperature, relative humidity, time
intervals, light, radiation energy, absorbed-dose rate, and other factors that might affect dosimeter response, as
well as quantities associated with the measurement instrument.
3.2.5.1
absorbed-dose rate
Ḋ
quotient of dD by dt, where dD is the increment of absorbed dose in the time interval dt
Note 1 to entry: It is expressed as
Ḋ = dD/dt
−1
Note 2 to entry: Unit: SI Gy·s .
[SOURCE: ICRU-85a, October 2011, 5.2.6, modified]
Note 3 to entry: The absorbed-dose rate is often specified in terms of its average value over longer time intervals,
−1 −1
for example, in units of Gy·min or Gy·h .
Note 4 to entry: In electron-beam irradiators with pulsed or scanned beam, there are two types of dose rate:
average value over several pulses (scans) and instantaneous value within a pulse (scan). These two values can be
significantly different.
[SOURCE: ISO/ASTM 51650:2013, 3.1.2]
3.2.6
type 1 dosimeter
dosimeter of high metrological quality, where the response of which is affected by individual influence
quantities in a well-defined way that can be expressed in terms of independent correction factors
[SOURCE: ISO/ASTM 52628:2013, 3.1.19, modified]
6 © ISO 2015 – All rights reserved

---------------------- Page: 11 ----------------------
ISO 12749-4:2015(E)

3.2.6.1
alanine dosimeter
specified quantity and physical form of the radiation-sensitive material alanine and any added inert
substance such as a binder, where the radiation-induced change in specific stable free radicals in
alanine is related to absorbed dose
Note 1 to entry: This may be a type 1 dosimeter.
[SOURCE: Adapted from ISO/ASTM 51607:2013, 3.1.2]
3.2.6.2
ceric-cerous dosimeter
specially prepared solution of ceric sulfate and cerous sulfate in sulfuric acid, individually sealed in an
appropriate container such as a glass ampoule, where the radiation-induced changes in electropotential
or optical absorbance of the solution are related to absorbed dose
[SOURCE: ISO/ASTM 51205:2009, 3.1.3]
Note 1 to entry: This may be a type 1 dosimeter.
3.2.6.3
dichromate dosimeter
solution containing silver and dichromate ions in perchloric acid in an appropriate container such as
a sealed glass ampoule that indicates absorbed dose by change (decrease) in absorbance at a specified
wavelength
[SOURCE: adapted from ISO/ASTM 51401:2013, 4.2]
Note 1 to entry: This may be a type 1 dosimeter.
3.2.6.4
ethanol chlorobenzene dosimeter
partly deoxygenated solution of chlorobenzene (CB) in 96 volume % ethanol in an appropriate container,
such as a flame-sealed glass ampoule, used to indicate absorbed dose by measurement of the amount of
HCl formed under irradiation
[SOURCE: ISO/ASTM 51538:2009, 3.1.4]
Note 1 to entry: This is may be a type 1 dosimeter.
3.2.6.5
Fricke dosimeter
air-saturated solution of ferrous sulfate or ferrous ammonium sulfate that indicates absorbed dose by
an increase in absorbance at a specified wavelength
[SOURCE: ASTM E1026:2013, 4.2]
Note 1 to entry: This may be a type 1 dosimeter.
3.2.7
type 2 dosimeter
response is affected by influence quantities in a complex way that cannot practically be expressed in
terms of independent correction factors
[SOURCE: ISO/ASTM 52628:2013, 3.1.20, modified]
© ISO 2015 – All rights reserved 7

---------------------- Page: 12 ----------------------
ISO 12749-4:2015(E)

3.2.7.1
calorimeter
assembly consisting of calorimetric body (absorber), thermal insulation, and temperature sensor
with wiring, that during exposure to ionizing radiation exhibits a characterizable change in absorber
temperature that can be related to absorbed dose
Note 1 to entry: This is a type 2 dosimeter.
[SOURCE: Adapted from ISO/ASTM 51631:2013, 3.2.2]
3.2.7.2
cellulose triacetate dosimeter
piece of CTA film that, during exposure to ionizing radiation, exhibits a quantifiable change in specific
net absorbance as a function of absorbed dose
[SOURCE: ISO/ASTM 51650:2013, 3.1.4]
Note 1 to entry: This is a type 2 dosimeter.
3.2.7.3
polymethylmethacrylate dosimeter
PMMA dosimeter
piece of specially selected or developed PMMA material, individually sealed by the manufacturer in an
impermeable sachet, that during exposure to ionizing radiation exhibits a characterizable change in
specific optical absorbance as a function of absorbed dose
[SOURCE: ISO/ASTM 51276:2012, 3.1.7]
3.2.7.4
radiochromic film dosimeter
specially prepared film containing ingredients that undergo change in optical absorbance under
ionizing radiation, which can be related to absorbed dose
[SOURCE: adapted from ISO/ASTM 51275:2013, 3.1.7]
3.2.7.5
radiochromic liquid dosimeter
specially prepared solution containing ingredients that undergo change in optical absorbance under
ionizing radiation, which can be related to absorbed dose
[SOURCE: adapted from ISO/ASTM 51540:2004, 3.1.7]
3.2.7.6
radiochromic optical waveguide dosimeter
specially prepared optical waveguide containing ingredients that undergo an ionizing radiation-
induced change in photometric absorbance, which can be related to absorbed dose
[SOURCE: adapted from ISO/ASTM 51310:2004, 3.1.8]
3.2.7.7
thermoluminescence dosimeter
TLD
thermoluminescence phosphor, alone or incorporated in a material, used for determining the absorbed
dose to materials
[SOURCE: ISO/ASTM 51956:2013, 3.1.13]
8 © ISO 2015 – All rights reserved

---------------------- Page: 13 ----------------------
ISO 12749-4:2015(E)

3.3 Terms related to radiation processing
3.3.1
radiation processing
intentional irradiation of products or materials to preserve, modify or improve their characteristics
[SOURCE: ISO/ASTM 52628:2013, 3.1.12]
3.3.2
radiation processing facility
establishment that uses ionizing radiation for the purpose of radiation processing
3.3.2.1
gamma facility
gamma-ray irradiation facility
gamma-ray radiation facility
establishment that uses gamma-emitting radionuclide source for the purpose of radiation processing
[SOURCE: ISO/ASTM 51608:2015, 3.2.3]
3.3.2.2
X-ray facility
X-ray (bremsstrahlung) facility
X-ray (bremsstrahlung) irradiation facility
X-ray (bremsstrahlung) radiation facility
establishment that uses X-radiation (bremsstrahlung) for the purpose of radiation processing
3.3.2.2.1
X-ray converter
X-ray (bremsstrahlung) converter
device for generating X-radiation (bremsstrahlung) from an electron beam, consisting of a target,
means for cooling the target, and a supporting structure
[SOURCE: ISO/ASTM 51608:2015, 3.1.16]
3.3.2.2.2
X-ray target
component of the X-ray converter that is struck by the electron beam and which produces X-radiation
(bremsstrahlung)
Note 1 to entry: X-ray target is usually made of metal with a high atomic number, high melting temperature, and
high thermal conductivity.
[SOURCE: adapted from ISO/ASTM 51608:2015, 3.2.4]
3.3.2.3
electron beam facility
establishment that uses electron beam accelerator for the purpose of radiation processing
3.3.3
validation
documented procedure for obtaining, recording and interpreting the results required to
establish that a process will consistently yield product complying with predetermined specifications
[SOURCE: ISO 11137-1:2006]
© ISO 2015 – All rights reserved 9

---------------------- Page: 14 ----------------------
ISO 12749-4:2015(E)

3.3.4
installation qualification
IQ
process of obtaining and documenting evidence that equipment has been provided and installed in
accordance with its specifications
[SOURCE: ISO/ASTM 51702:2013, 3.1.8]
3.3.4.1
electron beam spot
cross section of an unscanned beam in the reference plane
3.3.4.1.1
beam length
dimension of the irradiation zone, perpendicular to the beam width and direction of the electron beam
at a specified distance from the accelerator window
[SOURCE: ISO/ASTM 51649:2015, 3.1.4]
3.3.4.1.2
beam width
dimension of the irradiation zone perpendicular to the direction of product movement, at a specified
distance from the accelerator window
[SOURCE: ISO/ASTM 51649:2015, 3.1.5]
3.3.4.2
electron beam power
product of the average electron beam energy and the average beam current
[SOURCE: ISO/ASTM 51649:2015, 3.1.4]
3.3.4.2.1
average beam current
time-averaged electron beam current; for a pulsed accelerator, the averaging shall be done over a large
number of pulses
[SOURCE: ISO/ASTM 51649:2015, 3.1.2]
3.3.4.2.2
electron energy spectrum
particle fluence distribution of electrons as a function of energy
[SOURCE: ISO/ASTM 51649:2015, 3.1.12]
3.3.4.2.3
electron beam energy
kinetic energy of the accelerated electrons in the beam
Note 1 to entry: Unit: J.
−19
Note 2 to entry: Electron volt (eV) is often used as the unit for electron beam energy, where 1 eV = 1,602×10 J.
Note 3 to entry: In radiation processing, where beams with a broad electron energy spectrum are frequently
used, the terms most probable energy (E ) and average energy (E ) are common. They are linked to the practical
p a
electron range R and half-value depth R by empirical equations, respectively.
p 50
Note 4 to entry: Electron beam energy can be determined using established relationships between electron beam
energy and depth-dose distribution parameters. The method used for energy calculation must be specified.
[SOURCE: ISO/ASTM 51649:2015, 3.1.10. modified]
10 © ISO 2015 – All rights reserved

---------------------- Page: 15 ----------------------
ISO 12749-4:2015(E)

3.3.4.3
electron beam range
penetration distance in a specific, totally absorbing material along the beam axis of the electrons
incident on the material, equivalent to practical electron range, R
p
Note 1 to entry: R can be measured from experimental depth-dose distributions in a given material.
p
Note 2 to entry: Other forms of electron range are found in the dosimetry literature, for example, extrapolated
range derived from depth-dose data and the continuous-slowing-down-approximation range (the calculated
path length traversed by an electron in a material in the course of completely slowing down).
−2
Note 3 to entry: Electron range is usually expressed in terms of mass per unit area (kg·m ), but sometimes in
terms of thickness (m) for a specified material.
[SOURCE: ISO/ASTM 51649:2015, 3.2.5]
3.3.4.3.1
half-entrance depth
R
50e
depth in homogeneous material at which the absorbed dose has decreased down to 50 % of the absorbed
dose at the surface of the material
[SOURCE: ISO/ASTM 51649:2015, 3.2.7]
3.3.4.3.2
half-value depth
R
50
depth in homogeneous material at which the absorbed dose has decreased down to 50 % of its maximum
value
[SOURCE: ISO/ASTM 51649:2015, 3.2.8]
3.3.4.3.3
practical electron range
R
p
depth in homogeneous material to the point where the tangent at the steepest point (the inflection
point) on the almost straight descending portion of the depth-dose distribution curve meets the
extrapolated X-ray background
[SOURCE: ISO/ASTM 51649:2015, 3.2.10]
3.3.4.3.
...