ISO 7004:2002

Photography - Industrial radiographic films - Determination of ISO speed, ISO average gradient and ISO gradients G2 and G4 when exposed to X- and gamma-radiation

ISO 7004:2002 specifies methods for determining sensitometric curve shape, ISO speed, ISO average gradient and ISO gradients G2 and G4 for industrial radiographic systems consisting of film and film processing when exposed directly to X-rays and gamma-rays. The measurement of characteristics of film systems used in industrial radiography with fluorescent intensifying screens is not specified in this International Standard.

Photographie — Films pour radiographie industrielle — Détermination de la sensibilité ISO, du contraste moyen ISO et des contrastes ISO G2 et G4 après exposition à des rayons X ou gamma

Fotografija - Industrijski radiografski filmi - Določanje splošne občutljivosti ISO, povprečnega gradienta ISO in ISO-gradientov G2 in G4 pri ekspoziciji z X- in gama sevanjem

Ta mednarodni standard določa metode za določanje oblike senzitometrične krivulje, splošne občutljivosti ISO, povprečnega gradienta ISO in ISO-gradientov G2 in G4 za industrijske radiografske sisteme, sestavljene iz filma in procesiranja filma pri neposredni ekspoziciji z rentgenskimi žarki in žarki gama. Ta mednarodni standard ne določa merjenja značilnosti filmskih sistemov, ki se uporabljajo pri industrijski radiografiji z zasloni s fluorescenčno ojačitvijo. Enote za izmerjeno energijo so informativno navedene v dodatku A.

General Information

• Status: Published
• Publication Date: 02-Oct-2002
• ICS: 37.040.25 - Radiographic films
• Technical Committee: ISO/TC 42 - Photography
• Drafting Committee: ISO/TC 42/WG 3 - Image measurement, viewing and sensitometry
• Current Stage: 9093 - International Standard confirmed
• Start Date: 05-Jun-2021
• Completion Date: 13-Dec-2025
• Ref Project: SIST ISO 7004:2011 - Photography - Industrial radiographic films - Determination of ISO speed, ISO average gradient and ISO gradients G2 and G4 when exposed to X- and gamma-radiation

Relations

• Consolidated By: ISO 16017-2:2003 - Indoor, ambient and workplace air - Sampling and analysis of volatile organic compounds by sorbent tube/thermal desorption/capillary gas chromatography - Part 2: Diffusive sampling
• Effective Date: 06-Jun-2022
• Revises: ISO 7004:1987 - Photography - Industrial radiographic film - Determination of ISO speed and average gradient when exposed to X- and gamma-radiation
• Effective Date: 15-Apr-2008

Overview

ISO 7004:2002 - "Photography - Industrial radiographic films - Determination of ISO speed, ISO average gradient and ISO gradients G2 and G4 when exposed to X- and gamma-radiation" defines standardized test methods for measuring the sensitometric behavior of industrial radiographic film systems (film + processing) exposed directly to X‑ and γ‑radiation. The standard covers how to obtain a sensitometric curve and derive ISO speed, ISO average gradient, and point gradients G2 and G4. It does not apply to film systems used with fluorescent intensifying screens.

Key topics and requirements

• Scope and definitions - film system, system type, radiation quality, net and minimum density, gradients, etc.
• Sampling and storage - evaluate representative batches and store samples per manufacturer recommendations to reflect typical consumer use.
• Handling - films must be handled in complete darkness (no safelight exposure) during exposure and processing.
• Environmental conditions - samples exposed at 23 °C ± 5 °C and 50% ± 20% relative humidity.
• Exposure and radiation quality - four representative sources (two X‑ray, two γ‑ray) are specified to reflect practical use. X‑ray generator requirements (per ISO 4037‑1) include constant-voltage operation and high-voltage stability within ±1%.
• Filtration and tube specs - example X‑ray filtration requirements: low‑potential source with total filtration equivalent to 2.0 mm ± 0.1 mm Cu and half‑value layer adjustment (approx. 120 kV); high‑potential source with 8.00 mm ± 0.05 mm Cu equivalent (approx. 220 kV). (See standard for full radiation-quality details.)
• Processing and densitometry - film development must be defined when reporting results; density measurements follow ISO density standards (ISO 5‑2, ISO 5‑3).
• Evaluation and calculations - procedures to derive ISO speed, ISO average gradient, point gradients (G2, G4), uncertainty assessment, product classification, and marking/labeling requirements.
• Informative annexes - units of measured energy, scattered radiation measurement, ionization chamber calibration, and radiation quality codes.

Applications and users

ISO 7004:2002 is intended for practical use in:

• Radiographic film manufacturers reporting standardized film characteristics (ISO speed, contrast metrics).
• Non‑destructive testing (NDT) laboratories validating film performance for industrial radiography.
• Quality assurance and procurement teams specifying film systems for X‑ray and gamma radiography.
• Calibration and test laboratories performing sensitometric evaluations and comparative studies.
• Standards committees and regulatory bodies aligning national test methods with international practice.

When publishing ISO speed or gradient values, users must specify the radiation quality and film processing used, since results depend on both.

Related standards

• ISO 4037‑1: X and gamma reference radiation (radiation characteristics and production)
• ISO 5579: Radiographic examination - basic rules
• ISO 5‑2 / ISO 5‑3: Density measurements (geometric and spectral conditions)

Keywords: ISO 7004:2002, industrial radiographic films, ISO speed, ISO average gradient, G2 G4 gradients, X‑ray radiography, gamma‑ray radiography, sensitometric curve, film processing, NDT.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2011
)RWRJUDILMD,QGXVWULMVNLUDGLRJUDIVNLILOPL'RORþDQMHVSORãQHREþXWOMLYRVWL,62
SRYSUHþQHJDJUDGLHQWD,62LQ,62JUDGLHQWRY*LQ*SULHNVSR]LFLML];LQJDPD
VHYDQMHP
Photography - Industrial radiographic films - Determination of ISO speed, ISO average
gradient and ISO gradients G2 and G4 when exposed to X- and gamma-radiation
Photographie - Films pour radiographie industrielle - Détermination de la sensibilité ISO,
du contraste moyen ISO et des contrastes ISO G2 et G4 après exposition à des rayons
X ou gamma
Ta slovenski standard je istoveten z: ISO 7004:2002
ICS:
37.040.25 Radiografski filmi Radiographic films
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 7004
Second edition
2002-10-01
Photography — Industrial radiographic
films — Determination of ISO speed, ISO
average gradient and ISO gradients G2
and G4 when exposed to X- and
gamma-radiation
Photographie — Films pour radiographie industrielle — Détermination de la
sensibilité ISO, du contraste moyen ISO et des contrastes ISO G2 et G4
après exposition à des rayons X ou gamma

Reference number
©
ISO 2002
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2002
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.ch
Printed in Switzerland
ii © ISO 2002 – All rights reserved

Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 Sampling and storage. 3
5 Method of test. 3
5.1 Principle . 3
5.2 Safelights . 3
5.3 Exposure . 3
5.4 Processing . 5
5.5 Densitometry . 5
5.6 Evaluation . 6
6 Product classification. 6
6.1 Speed calculation. 6
6.2 Average gradient calculation . 9
6.3 Point gradient determination . 9
6.4 Uncertainty. 10
7 Marking and labelling. 10
7.1 ISO speed. 10
7.2 ISO average gradient . 10
7.3 ISO gradients G2 and G4. 11
7.4 General . 11
Annex A (informative) Units of measured energy . 12
Annex B (informative) Scattered radiation measurement . 13
Annex C (informative) Calibration of ionization chambers . 14
Annex D (informative) Improvement of the reproducibility of measurement of X-radiation. 15
Annex E (informative) Derivation of the relationship used in the determination of G2 and G4 . 16
Annex F (informative) Radiation quality code. 17
Bibliography. 18

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 7004 was prepared by Technical Committee ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 7004:1987), of which it constitutes a technical
revision.
Annexes A to F of this International Standard are for information only.
iv © ISO 2002 – All rights reserved

Introduction
This International Standard specifies methods for measuring the ISO speed, ISO average gradient and ISO
gradients G2 and G4 of industrial radiographic film systems when exposed directly to X- and γ-radiation. Many
countries have had national standards relating to this subject for many years and may provide values which are
different from those obtained by following the procedure specified in this International Standard. Because the
photographic characteristics of a film system are dependent on the energy distribution in the wavelength spectrum,
four representative sources are specified for determining sensitometric characteristics. To minimize the differences
between national standards and this International Standard, the minimum requirements for X-ray tubes and X-ray
generators have been considered mandatory and have been clearly specified in the subclause on radiation quality
(5.3.3). This International Standard imposes limiting specifications on the thickness of the metallic screens often
used in conjunction with the film as specified in the basic rules for good radiographic practice in ISO 5579.
Photographic results are also dependent on the chemical process used to develop the film. This International
Standard does not attempt to specify the processing method; therefore, when ISO speed or ISO gradient values
are given for a film system, it is necessary to specify not only the radiation quality used but also the process. This
will permit the comparison of systems consisting of film and film processing.

INTERNATIONAL STANDARD ISO 7004:2002(E)

Photography — Industrial radiographic films — Determination of
ISO speed, ISO average gradient and ISO gradients G2 and G4
when exposed to X- and gamma-radiation
1 Scope
This International Standard specifies methods for determining sensitometric curve shape, ISO speed, ISO average
gradient and ISO gradients G2 and G4 for industrial radiographic systems consisting of film and film processing
when exposed directly to X-rays and γ-rays. The measurement of characteristics of film systems used in industrial
radiography with fluorescent intensifying screens is not specified in this International Standard.
NOTE Units of measured energy are given for information in annex A.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 5-2: 2001, Photography — Density measurements — Part 2: Geometric conditions for transmission density
ISO 5-3:1995, Photography — Density measurements — Part 3: Spectral conditions
ISO 4037-1:1996, X and gamma reference radiation for calibrating dosemeters and doserate meters and for
determining their response as a function of photon energy — Part 1: Radiation characteristics and production
methods
ISO 5579: 1998, Non-destructive testing — Radiographic examination of metallic material by X- and gamma
rays — Basic rules
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
radiographic film
transparent plastic sheet coated on one or both sides with a photographically sensitive layer
3.2
film system
system consisting of a radiographic film, the film processing and, when in use, the lead foil(s) and film holder
3.3
system type
all film systems manufactured in the same way and of the same specification, but without consideration of the
format
NOTE A particular system type is specified by the type of film, type of processing and, when in use, the type of lead foil(s)
and film holder.
3.4
film/screen combination
radiographic film in direct contact with metallic screen(s) during exposure to X- or g-radiation
NOTE Within the scope of this International Standard, the screens are lead foils.
3.5
radiation quality
characteristic of ionizing radiation, determined by its spectral distribution with respect to energy
3.6
exposure technique
radiation source and filtration of the radiation beam in order to obtain a specified radiation quality at the source side
of the film or film/screen combination holder
3.7
minimum density
D
min
ISO standard visual diffuse transmission density, D , of an unexposed and processed sample of the film under test
T
3.8
net density
D
N
ISO standard visual diffuse transmission density, D , of an exposed and processed film minus the minimum
T
density, D , of the film under test
min
3.9
speed
quantitative measure of the response of the photographic material to radiant energy for specified conditions of
exposure, processing and image measurement
3.10
average gradient
G
slope of the straight line joining two specified points on a sensitometric curve
3.11
gradient
Gx
slope dD/d log K of the tangent to the sensitometric curve at a specified net density D = x
N
NOTE It is a measure of the contrast obtainable with the film system.
3.12
gray
Gy
special name for the unit of air kerma and the unit of absorbed dose, which is joule per kilogram
NOTE 1 Gy = 1 J/kg of air. 1 Gy is equivalent to 114,5 R or is equivalent to 0,029 5 C/kg.
2 © ISO 2002 – All rights reserved

4 Sampling and storage
In determining the sensitometric curve, ISO speed, ISO average gradient and ISO gradients G2 and G4 of a film
system, it is important that the samples evaluated yield the average results obtained by users. This will require
evaluating several different batches periodically under conditions specified in this International Standard. Prior to
evaluation, the samples shall be stored according to the manufacturer’s recommendations for a length of time that
simulates the average age at which the product is normally used. Several independent evaluations shall be made
to ensure the proper calibration of equipment and processes. The basic objective in selecting and storing samples
as described above is to ensure that the film characteristics are representative of those obtained by a consumer at
the time of use.
5 Method of test
5.1 Principle
Samples are exposed and processed as specified in 5.3 and 5.4. Measurements are obtained from the resultant
images to produce a sensitometric curve from which values are taken and used to determine ISO speed, ISO
average gradient and ISO gradients G2 and G4.
5.2 Safelights
To eliminate the possibility of safelight illumination affecting the sensitometric results, all films shall be handled in
complete darkness during exposure and processing.
5.3 Exposure
5.3.1 Film holders
Film/screen combinations shall be exposed in holders which provide less than 2 % absorption of the radiation
specified (without taking into account lead screens).
5.3.2 Sample condition
During exposure, the samples shall be at a temperature of 23 °C ± 5 °C and in equilibrium with air at a relative
humidity of 50 % ± 20 %.
5.3.3 Radiation quality
5.3.3.1 General
Four specific exposing sources (two X-ray sources and two g-ray sources) are recognized in this International
Standard to cover the range of exposing conditions used in practice. The selection of which of the four sources is
used to determine ISO speed, ISO average gradient and ISO gradients G2 and G4 depends on how the film
system is used.
To improve the reproducibility of exposures when X-ray tubes are used, the X-ray generator shall fulfil the following
requirements (based on ISO 4037-1):
a) X-radiations shall be produced by an X-ray unit of the constant-voltage type;
b) during an irradiation, the main value of the high voltage shall be stable within ± 1 %; it should be possible to
display the mean value of the high voltage with a tolerance of ± 1 %;
c) the target of the X-ray tube shall be made of tungsten and shall be of the reflection type; the target angle
should be about 22°.
5.3.3.2 X-rays from a low potential source
The film/screen combination under test shall be exposed to X-rays from tungsten target tubes. Inherent filtration of
the tube, plus an additional copper filter located as close to the target as possible shall provide a filtration
equivalent to 2,0 mm ± 0,1 mm of copper. All copper filters specified in this International Standard shall be made of
99,9 % pure copper.
The potential across the X-ray tube shall be adjusted until the half-value absorption is obtained with
1,0 mm ± 0,1 mm of copper (i.e. the intensity of the X-ray beam with a filtration equivalent to 3,0 mm shall be one-
half the value obtained with the total filtration equivalent to 2,0 mm of copper).
A potential of approximately 120 kV generally meets this requirement. No lead screens shall be used.
This is designated source (1).
5.3.3.3 X-rays from a high potential source
The film/screen combination under test shall be exposed to X-rays from tungsten target tubes. Inherent filtration of
the tube, plus an additional copper filter located as close to the target as possible shall provide a filtration
equivalent to 8,00 mm ± 0,05 mm of copper. The potential across the X-ray tube shall be adjusted until the half-
value absorption is obtained with 3,5 mm ± 0,2 mm of co
...

INTERNATIONAL ISO
STANDARD 7004
Second edition
2002-10-01
Photography — Industrial radiographic
films — Determination of ISO speed, ISO
average gradient and ISO gradients G2
and G4 when exposed to X- and
gamma-radiation
Photographie — Films pour radiographie industrielle — Détermination de la
sensibilité ISO, du contraste moyen ISO et des contrastes ISO G2 et G4
après exposition à des rayons X ou gamma

Reference number
©
ISO 2002
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2002
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.ch
Printed in Switzerland
ii © ISO 2002 – All rights reserved

Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 Sampling and storage. 3
5 Method of test. 3
5.1 Principle . 3
5.2 Safelights . 3
5.3 Exposure . 3
5.4 Processing . 5
5.5 Densitometry . 5
5.6 Evaluation . 6
6 Product classification. 6
6.1 Speed calculation. 6
6.2 Average gradient calculation . 9
6.3 Point gradient determination . 9
6.4 Uncertainty. 10
7 Marking and labelling. 10
7.1 ISO speed. 10
7.2 ISO average gradient . 10
7.3 ISO gradients G2 and G4. 11
7.4 General . 11
Annex A (informative) Units of measured energy . 12
Annex B (informative) Scattered radiation measurement . 13
Annex C (informative) Calibration of ionization chambers . 14
Annex D (informative) Improvement of the reproducibility of measurement of X-radiation. 15
Annex E (informative) Derivation of the relationship used in the determination of G2 and G4 . 16
Annex F (informative) Radiation quality code. 17
Bibliography. 18

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 7004 was prepared by Technical Committee ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 7004:1987), of which it constitutes a technical
revision.
Annexes A to F of this International Standard are for information only.
iv © ISO 2002 – All rights reserved

Introduction
This International Standard specifies methods for measuring the ISO speed, ISO average gradient and ISO
gradients G2 and G4 of industrial radiographic film systems when exposed directly to X- and γ-radiation. Many
countries have had national standards relating to this subject for many years and may provide values which are
different from those obtained by following the procedure specified in this International Standard. Because the
photographic characteristics of a film system are dependent on the energy distribution in the wavelength spectrum,
four representative sources are specified for determining sensitometric characteristics. To minimize the differences
between national standards and this International Standard, the minimum requirements for X-ray tubes and X-ray
generators have been considered mandatory and have been clearly specified in the subclause on radiation quality
(5.3.3). This International Standard imposes limiting specifications on the thickness of the metallic screens often
used in conjunction with the film as specified in the basic rules for good radiographic practice in ISO 5579.
Photographic results are also dependent on the chemical process used to develop the film. This International
Standard does not attempt to specify the processing method; therefore, when ISO speed or ISO gradient values
are given for a film system, it is necessary to specify not only the radiation quality used but also the process. This
will permit the comparison of systems consisting of film and film processing.

INTERNATIONAL STANDARD ISO 7004:2002(E)

Photography — Industrial radiographic films — Determination of
ISO speed, ISO average gradient and ISO gradients G2 and G4
when exposed to X- and gamma-radiation
1 Scope
This International Standard specifies methods for determining sensitometric curve shape, ISO speed, ISO average
gradient and ISO gradients G2 and G4 for industrial radiographic systems consisting of film and film processing
when exposed directly to X-rays and γ-rays. The measurement of characteristics of film systems used in industrial
radiography with fluorescent intensifying screens is not specified in this International Standard.
NOTE Units of measured energy are given for information in annex A.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 5-2: 2001, Photography — Density measurements — Part 2: Geometric conditions for transmission density
ISO 5-3:1995, Photography — Density measurements — Part 3: Spectral conditions
ISO 4037-1:1996, X and gamma reference radiation for calibrating dosemeters and doserate meters and for
determining their response as a function of photon energy — Part 1: Radiation characteristics and production
methods
ISO 5579: 1998, Non-destructive testing — Radiographic examination of metallic material by X- and gamma
rays — Basic rules
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
radiographic film
transparent plastic sheet coated on one or both sides with a photographically sensitive layer
3.2
film system
system consisting of a radiographic film, the film processing and, when in use, the lead foil(s) and film holder
3.3
system type
all film systems manufactured in the same way and of the same specification, but without consideration of the
format
NOTE A particular system type is specified by the type of film, type of processing and, when in use, the type of lead foil(s)
and film holder.
3.4
film/screen combination
radiographic film in direct contact with metallic screen(s) during exposure to X- or g-radiation
NOTE Within the scope of this International Standard, the screens are lead foils.
3.5
radiation quality
characteristic of ionizing radiation, determined by its spectral distribution with respect to energy
3.6
exposure technique
radiation source and filtration of the radiation beam in order to obtain a specified radiation quality at the source side
of the film or film/screen combination holder
3.7
minimum density
D
min
ISO standard visual diffuse transmission density, D , of an unexposed and processed sample of the film under test
T
3.8
net density
D
N
ISO standard visual diffuse transmission density, D , of an exposed and processed film minus the minimum
T
density, D , of the film under test
min
3.9
speed
quantitative measure of the response of the photographic material to radiant energy for specified conditions of
exposure, processing and image measurement
3.10
average gradient
G
slope of the straight line joining two specified points on a sensitometric curve
3.11
gradient
Gx
slope dD/d log K of the tangent to the sensitometric curve at a specified net density D = x
N
NOTE It is a measure of the contrast obtainable with the film system.
3.12
gray
Gy
special name for the unit of air kerma and the unit of absorbed dose, which is joule per kilogram
NOTE 1 Gy = 1 J/kg of air. 1 Gy is equivalent to 114,5 R or is equivalent to 0,029 5 C/kg.
2 © ISO 2002 – All rights reserved

4 Sampling and storage
In determining the sensitometric curve, ISO speed, ISO average gradient and ISO gradients G2 and G4 of a film
system, it is important that the samples evaluated yield the average results obtained by users. This will require
evaluating several different batches periodically under conditions specified in this International Standard. Prior to
evaluation, the samples shall be stored according to the manufacturer’s recommendations for a length of time that
simulates the average age at which the product is normally used. Several independent evaluations shall be made
to ensure the proper calibration of equipment and processes. The basic objective in selecting and storing samples
as described above is to ensure that the film characteristics are representative of those obtained by a consumer at
the time of use.
5 Method of test
5.1 Principle
Samples are exposed and processed as specified in 5.3 and 5.4. Measurements are obtained from the resultant
images to produce a sensitometric curve from which values are taken and used to determine ISO speed, ISO
average gradient and ISO gradients G2 and G4.
5.2 Safelights
To eliminate the possibility of safelight illumination affecting the sensitometric results, all films shall be handled in
complete darkness during exposure and processing.
5.3 Exposure
5.3.1 Film holders
Film/screen combinations shall be exposed in holders which provide less than 2 % absorption of the radiation
specified (without taking into account lead screens).
5.3.2 Sample condition
During exposure, the samples shall be at a temperature of 23 °C ± 5 °C and in equilibrium with air at a relative
humidity of 50 % ± 20 %.
5.3.3 Radiation quality
5.3.3.1 General
Four specific exposing sources (two X-ray sources and two g-ray sources) are recognized in this International
Standard to cover the range of exposing conditions used in practice. The selection of which of the four sources is
used to determine ISO speed, ISO average gradient and ISO gradients G2 and G4 depends on how the film
system is used.
To improve the reproducibility of exposures when X-ray tubes are used, the X-ray generator shall fulfil the following
requirements (based on ISO 4037-1):
a) X-radiations shall be produced by an X-ray unit of the constant-voltage type;
b) during an irradiation, the main value of the high voltage shall be stable within ± 1 %; it should be possible to
display the mean value of the high voltage with a tolerance of ± 1 %;
c) the target of the X-ray tube shall be made of tungsten and shall be of the reflection type; the target angle
should be about 22°.
5.3.3.2 X-rays from a low potential source
The film/screen combination under test shall be exposed to X-rays from tungsten target tubes. Inherent filtration of
the tube, plus an additional copper filter located as close to the target as possible shall provide a filtration
equivalent to 2,0 mm ± 0,1 mm of copper. All copper filters specified in this International Standard shall be made of
99,9 % pure copper.
The potential across the X-ray tube shall be adjusted until the half-value absorption is obtained with
1,0 mm ± 0,1 mm of copper (i.e. the intensity of the X-ray beam with a filtration equivalent to 3,0 mm shall be one-
half the value obtained with the total filtration equivalent to 2,0 mm of copper).
A potential of approximately 120 kV generally meets this requirement. No lead screens shall be used.
This is designated source (1).
5.3.3.3 X-rays from a high potential source
The film/screen combination under test shall be exposed to X-rays from tungsten target tubes. Inherent filtration of
the tube, plus an additional copper filter located as close to the target as possible shall provide a filtration
equivalent to 8,00 mm ± 0,05 mm of copper. The potential across the X-ray tube shall be adjusted until the half-
value absorption is obtained with 3,5 mm ± 0,2 mm of copper.
A potential of approximately 220 kV generally meets this requirement.
Film/screen combinations shall be exposed without interleaving paper and shall be between lead-foil screens. A
trial exposure should be made to make sure that the lead-foil screens do not produce streaks or other obvious
defects.
The front and back lead-foil screens shall be between 0,020 mm and 0,150 mm thick.
It should be noted that changes in screen thickness may result in changes in the sensitometric characteristics.
Therefore, screen thickness shal
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