SIST EN 60627:2002
(Main)Diagnostic X-ray imaging equipment - Characteristics of general purpose and mammographic anti-scatter grids (IEC 60627:2001)
Diagnostic X-ray imaging equipment - Characteristics of general purpose and mammographic anti-scatter grids (IEC 60627:2001)
Deals with the definitions, determination and indication of characteristics of anti-scatter grids used in diagnostic X-ray imaging equipment, in order to reduce the incidence of scattered radiation, produced particularly in the body of the patient, upon the image reception area and thus to improve the contrast of the X-ray pattern. Only linear grids are considered in this standard. This standard is intended to be applied for the demonstration of the characteristics of anti-scatter grids under test conditions.
Bildgebende Geräte für die Röntgendiagnostik - Kenngrößen von Streustrahlenrastern für die allgemeine Anwendung und für die Mammographie (IEC 60627:2001)
Equipements de diagnostic par imagerie à rayonnement X - Caractéristiques des grilles antidiffusantes d'usage général et de mammographie (IEC 60627:2001)
Traite des définitions, de la détermination et de l'indication des caractéristiques des grilles antidiffusantes utilisées dans les équipements de diagnostic par imagerie à rayonnement X, afin de réduire l'influence du rayonnement diffusé produit en particulier dans le corps du patient, sur la surface réceptrice de l'image et d'améliorer ainsi le contraste de l'image radiologique potentielle. Cette norme ne traite que des grilles linéaires. Il est prévu que cette norme soit appliquée à la démonstration des caractéristiques des grilles antidiffusantes dans des conditions d'essai.
Diagnostična oprema za rentgensko slikanje – Značilnosti splošnonamenske in mamografske protirazpršilne mrežice (IEC 60627:2001)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 60627:2002
01-junij-2002
1DGRPHãþD
SIST EN 61953:1998
'LDJQRVWLþQDRSUHPD]DUHQWJHQVNRVOLNDQMH±=QDþLOQRVWLVSORãQRQDPHQVNHLQ
PDPRJUDIVNHSURWLUD]SUãLOQHPUHåLFH ,(&
Diagnostic X-ray imaging equipment - Characteristics of general purpose and
mammographic anti-scatter grids (IEC 60627:2001)
Bildgebende Geräte für die Röntgendiagnostik - Kenngrößen von Streustrahlenrastern
für die allgemeine Anwendung und für die Mammographie (IEC 60627:2001)
Equipements de diagnostic par imagerie à rayonnement X - Caractéristiques des grilles
antidiffusantes d'usage général et de mammographie (IEC 60627:2001)
Ta slovenski standard je istoveten z: EN 60627:2001
ICS:
11.040.50 Radiografska oprema Radiographic equipment
SIST EN 60627:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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EUROPEAN STANDARD EN 60627
NORME EUROPÉENNE
EUROPÄISCHE NORM November 2001
ICS 11.040.50
English version
Diagnostic X-ray imaging equipment -
Characteristics of general purpose and mammographic anti-scatter grids
(IEC 60627:2001)
Equipements de diagnostic par imagerie Bildgebende Geräte
à rayonnement X - für die Röntgendiagnostik -
Caractéristiques des grilles antidiffusantes Kenngrößen von Streustrahlenrastern
d'usage général et de mammographie für die allgemeine Anwendung
(CEI 60627:2001) und für die Mammographie
(IEC 60627:2001)
This European Standard was approved by CENELEC on 2001-11-01. CENELEC 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 Central Secretariat or to any CENELEC 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 CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,
Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60627:2001 E
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EN 60627:2001 - 2 -
Foreword
The text of document 62B/436A/FDIS, future edition 2 of IEC 60627, prepared by SC 62B, Diagnostic
imaging equipment, of IEC TC 62, Electrical equipment in medical practice, was submitted to the IEC-
CENELEC parallel vote and was approved by CENELEC as EN 60627 on 2001-11-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2002-08-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2004-11-01
Annexes designated "normative" are part of the body of the standard.
In this standard, annexes A, B and ZA are normative.
Annex ZA has been added by CENELEC.
In this standard, the following print types are used:
– requirements, compliance with which can be tested, and definitions: in roman type;
– explanations, advice, notes, general statements, exceptions and references: in smaller roman type;
– test specifications: in italic type;
– TERMS DEFINED IN EN 60601-1, IN EN 60788, IN CLAUSE 3 OF THIS STANDARD OR IN OTHER IEC
PUBLICATIONS REFERENCED IN ANNEX B: IN SMALL CAPITALS.
__________
Endorsement notice
The text of the International Standard IEC 60627:2001 was approved by CENELEC as a European
Standard without any modification.
__________
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- 3 - EN 60627:2001
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60417 Series Graphical symbols for use on equipment EN 60417 Series
1) 2)
IEC 60601-1 - Medical electrical equipment EN 60601-1 1990
Part 1: General requirements for safety + corr. July 1994
+ A13 1996
1) 2)
IEC 60788 - Medical radiology - Terminology HD 501 S1 1988
1)
IEC 61223-1 - Evaluation and routine testing in --
medical imaging departments
Part 1: General aspects
1) 2)
IEC 61267 - Medical diagnostic X-ray equipment - EN 61267 1994
Radiation conditions for use in the
determination of characteristics
1)
Undated reference.
2)
Valid edition at time of issue.
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NORME CEI
INTERNATIONALE IEC
60627
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2001-08
Equipements de diagnostic par imagerie
à rayonnement X –
Caractéristiques des grilles antidiffusantes
d'usage général et de mammographie
Diagnostic X-ray imaging equipment –
Characteristics of general purpose and
mammographic anti-scatter grids
IEC 2001 Droits de reproduction réservés Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun procédé, any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission in
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
U
PRICE CODE
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue
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60627 © IEC:2001 – 3 –
CONTENTS
FOREWORD.5
INTRODUCTION.9
1 Scope and object.11
2 Normative references .11
3 Terminology .13
3.1 Degree of requirements .13
3.2 Use of terms.13
3.3 Defined terms.13
4 Structure of ANTI-SCATTER GRIDS .19
5 Measurement and determination of physical characteristics.21
5.1 Method and arrangement for measurement .21
5.2 Physical characteristics .27
6 Requirements for ANTI-SCATTER GRIDS.31
6.1 Manufacturing tolerances .31
6.2 Determination of the APPLICATION LIMITS for PARALLEL GRIDS and FOCUSED GRIDS .31
6.3 Accuracy of characteristics.31
6.4 Marking and ACCOMPANYING DOCUMENTS .33
6.5 Statement of compliance .35
Annex A (normative) Calculation of the APPLICATION LIMITS.49
Annex B (normative) Terminology – Index of defined terms.51
Bibliography.55
Figure 1 – Structure of ANTI-SCATTER GRIDS .37
Figure 2 – RADIATION DETECTOR.39
Figure 3a – Measurement arrangement for general purpose ANTI-SCATTER GRIDS
with NARROW-BEAM CONDITION (determination of the TRANSMISSION OF PRIMARY RADIATION).41
Figure 3b – Measurement arrangement for MAMMOGRAPHIC ANTI-SCATTER GRIDS with
NARROW-BEAM CONDITION (determination of the TRANSMISSION OF PRIMARY RADIATION).43
Figure 4a – Measurement arrangement for general purpose ANTI-SCATTER GRIDS
with BROAD-BEAM CONDITION (determination of the TRANSMISSION OF SCATTERED RADIATION) .45
Figure 4b – Measurement arrangement for MAMMOGRAPHIC ANTI-SCATTER GRIDS
with BROAD-BEAM CONDITION (determination of the TRANSMISSION OF SCATTERED RADIATION) .47
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60627 © IEC:2001 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIAGNOSTIC X-RAY IMAGING EQUIPMENT –
Characteristics of general purpose and mammographic
anti-scatter grids
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60627 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
This second edition cancels and replaces the first edition published in 1978, and constitutes a
technical revision. It also cancels and replaces IEC 61953 published in 1997 which is
incorporated in this standard technically unchanged.
The text of this standard is based on the following documents:
FDIS Report on voting
62B/436A/FDIS 62B/441/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
Annexes A and B form an integral part of this standard.
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60627 © IEC:2001 – 7 –
In this standard, the following print types are used:
– requirements, compliances with which can be tested, and definitions: in roman type;
– explanations, advice, notes, general statements, exceptions and references: in smaller roman type;
– test specifications: in italic type;
– TERMS DEFINED IN IEC 60601-1, IN IEC 60788, IN CLAUSE 3 OF THIS STANDARD OR IN OTHER IEC
PUBLICATIONS REFERENCED IN ANNEX B: IN SMALL CAPITALS.
The committee has decided that the contents of this publication will remain unchanged
until 2007. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
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60627 © IEC:2001 – 9 –
INTRODUCTION
The first edition of IEC 60627 was intended for ANTI-SCATTER GRIDS used in general radio-
graphy and is not appropriate for ANTI-SCATTER GRIDS used in mammography. As a
consequence, a complementary standard IEC 61953 was published. During the preparation of
this latter standard, it became clear that a revision of IEC 60627 itself was necessary, and it
was decided to merge together the two standards covering ANTI-SCATTER GRIDS. Wherever
possible, a harmonized approach has been used. Where there are differences in this standard
between general purpose ANTI-SCATTER GRIDS and MAMMOGRAPHIC ANTI-SCATTER GRIDS, these
are listed as items a) and b) respectively.
Some of the differences for general purpose ANTI-SCATTER GRIDS between this second edition
and the first edition of IEC 60627 are outlined below:
– some definitions have been modified and others added to improve clarity, harmonization
or generality;
– the concept of a reference ANTI-SCATTER GRID is now omitted. It was found that such ANTI-
SCATTER GRIDS were little used. It should be sufficient to define unambiguously the
RADIATION DETECTOR and the measuring procedure;
–the same PHANTOM is used for measurements of TRANSMISSION OF PRIMARY RADIATION and
TRANSMISSION OF SCATTERED RADIATION;
–the RADIATION QUALITIES used for the measurement have been changed and are now
qualities specified in IEC 61267;
– a lower energy X-RAY SPECTRUM than before is used to measure the performance of
general purpose ANTI-SCATTER GRIDS. This was considered to be more appropriate than the
spectrum previously used;
– where a general purpose ANTI-SCATTER GRID is specified for low-energy use, additional
measurements have now to be made with appropriate, specified RADIATION QUALITIES;
– the diameter of the measuring field is reduced;
–the TRANSMISSION OF PRIMARY RADIATION is now given on the ANTI-SCATTER GRID or in the
ACCOMPANYING DOCUMENTS;
– information on the nature of the material used for the grid interspace and on the nature of
the grid covers is now given in the ACCOMPANYING DOCUMENTS;
– application limits are now given for PARALLEL GRIDS;
– the position of the grid centre is now indicated.
Special laboratory provisions and carefully controlled test conditions are needed for the
measurements described here.
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60627 © IEC:2001 – 11 –
DIAGNOSTIC X-RAY IMAGING EQUIPMENT –
Characteristics of general purpose and mammographic
anti-scatter grids
1 Scope and object
This International Standard deals with the definitions, determination and indication of
characteristics of ANTI-SCATTER GRIDS used in diagnostic X-ray imaging equipment, in order to
reduce the incidence of SCATTERED RADIATION, produced particularly in the body of the
PATIENT, upon the IMAGE RECEPTION AREA and thus to improve the contrast of the X-RAY
PATTERN.
In this standard only LINEAR GRIDS are considered.
Since at present only FOCUSED GRIDS are used in mammography, this standard is restricted to
FOCUSED GRIDS for MAMMOGRAPHIC ANTI-SCATTER GRIDS.
This standard is not intended to be applied for ACCEPTANCE TESTS.
This standard does not cover the homogeneity of performance over the area of a grid.
This standard is intended to be applied for the demonstration of the characteristics of ANTI-
SCATTER GRIDS under test conditions. These conditions are not usually available at the USER's
site.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60417 (all parts), Graphical symbols for use on equipment
IEC 60601-1, Medical electrical equipment – Part 1: General requirements for safety
IEC 60788, Medical radiology – Terminology
IEC 61223-1, Evaluation and routine testing in medical imaging departments – Part 1: General
aspects
IEC 61267, Medical diagnostic X-ray equipment – Radiation conditions for use in the
determination of characteristics
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60627 © IEC:2001 – 13 –
3 Terminology
3.1 Degree of requirements
In this standard, certain terms which are not printed in SMALL CAPITALS have particular
meanings:
– "shall" indicates a requirement that is mandatory for compliance;
– "should" indicates a strong recommendation that is not mandatory for compliance;
– "may" indicates a permitted manner of complying with a requirement or of avoiding
the need to comply;
– "specific" is used to indicate definitive information stated in this standard or
referenced in other standards, usually concerning particular operating
conditions, test arrangements or values connected with compliance;
– "specified" is used to indicate definitive information stated by the MANUFACTURER in
ACCOMPANYING DOCUMENTS or in other documentation relating to the
EQUIPMENT under consideration, usually concerning its intended purpose, or
the parameters or conditions associated with its use or with testing to
determine compliance.
3.2 Use of terms
In this standard, terms printed in SMALL CAPITALS are used as defined in IEC 60601-1, in
IEC 60788, in 3.3 of this standard or in other IEC publications referenced in annex B.
NOTE Attention is drawn to the fact, that in cases where the concept addressed is not strongly confined to the
definition given in one of the publications listed above a corresponding term is printed in lower-case letters.
An index of defined terms used in this standard is given in annex B.
3.3 Defined terms
For the purpose of this International Standard, the following definitions apply.
NOTE Some of the defined terms given in this standard deviate from those given in the current edition of
IEC 60788.
3.3.1
ANTI-SCATTER GRID
device with a fixed periodic arrangement of materials with different X-ray ATTENUATION
properties to be placed in front of the IMAGE RECEPTION AREA in order to reduce the incidence
of SCATTERED RADIATION upon that area and thus increase the contrast in the X-RAY PATTERN
3.3.2
LINEAR GRID
ANTI-SCATTER GRID composed of highly absorbing strips and highly transmitting interspaces
which are parallel in their longitudinal direction
3.3.3
PARALLEL GRID
LINEAR GRID in which the planes of the absorbing strips are parallel to each other and
perpendicular to the incident face
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60627 © IEC:2001 – 15 –
3.3.4
FOCUSED GRID
LINEAR GRID in which the planes of the absorbing strips converge to a straight line at the
FOCUSING DISTANCE
3.3.5
TAPERED GRID
LINEAR GRID in which the height of the absorbing strips decreases as the distance between the
absorbing strips and the TRUE CENTRAL LINE increases. This decrease is symmetrical about
the TRUE CENTRAL LINE
3.3.6
CROSS-GRID
ANTI-SCATTER GRID composed of two LINEAR GRIDS built together in such a way that the
directions of their absorbing strips form an angle
3.3.6.1
ORTHOGONAL CROSS-GRID
CROSS-GRID in which the directions of the absorbing strips form an angle of 90°
3.3.6.2
OBLIQUE CROSS-GRID
CROSS-GRID in which the directions of the absorbing strips form an angle other than 90°
3.3.7
STATIONARY GRID
ANTI-SCATTER GRID used in such a way that it does not move in relation to the RADIATION BEAM
3.3.8
MOVING GRID
ANTI-SCATTER GRID used in an ACCESSORY that enables the ANTI-SCATTER GRID to be moved,
when irradiated by a RADIATION BEAM, in order to avoid the imaging of the absorbing strips and
the consequent loss of information
3.3.9
MAMMOGRAPHIC ANTI-SCATTER GRID
FOCUSED GRID specially designed for mammography
NOTE In this standard the term "general purpose ANTI-SCATTER GRID" is used to describe any ANTI-SCATTER GRID
not specially designed for mammography.
3.3.10
Geometric characteristics
3.3.10.1
GRID RATIO, r
ratio between the height of the absorbing strips and the distance between the absorbing strips
in the centre of a LINEAR GRID
3.3.10.2
FOCUSING DISTANCE, f
0
distance between the incident face of a FOCUSED GRID and the line into which the planes of the
absorbing strips of the grid converge (unit: cm)
NOTE Attention is drawn to the differences between "FOCUSING DISTANCE", "FOCAL SPOT to grid distance" and
"FOCAL SPOT to film distance".
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60627 © IEC:2001 – 17 –
3.3.10.3
APPLICATION LIMITS, f , f
1 2
lower, f , and upper, f , limits of the distance from the FOCAL SPOT to the incident face of a
1 2
FOCUSED GRID or a PARALLEL GRID between which the obtained radiological information can be
considered acceptable for many purposes (unit: cm)
NOTE See annex A for details on the calculation of the APPLICATION LIMITS.
3.3.10.4
TRUE CENTRAL LINE
–for a PARALLEL GRID: line on the incident face in the direction of the absorbing strips
and passing through the centre of the grid area
–for a FOCUSED GRID: perpendicular projection onto the incident face of the grid, of the
line into which the planes of the absorbing strips converge
–for a TAPERED GRID: line on the incident face in the direction of the absorbing strips
and lying within a symmetry plane of the grid structure
NOTE A CROSS-GRID has two TRUE CENTRAL LINES.
3.3.10.5
CENTRAL LINE INDICATION
marking on the incident face of a LINEAR GRID, which is intended to indicate the position and
direction of the TRUE CENTRAL LINE
NOTE In most cases, this marking coincides with the geometric centre line of the grid's incident face.
3.3.10.6
STRIP FREQUENCY, N
–1
number of absorbing strips per unit length of a LINEAR GRID (unit: cm )
NOTE This term replaces the previous term "STRIPS PER CENTIMETRE".
3.3.11
Physical characteristics
3.3.11.1
TRANSMISSION OF PRIMARY RADIATION, T
p
characteristic of an object, evaluated as the ratio of the MEASURED VALUE of the quantity or
rate of PRIMARY RADIATION with the object placed in a RADIATION BEAM to that with the object
removed from the beam, under specific measuring conditions
3.3.11.2
TRANSMISSION OF SCATTERED RADIATION, T
s
characteristic of an object, evaluated as the ratio of the MEASURED VALUE of the quantity or
rate of SCATTERED RADIATION with the object placed in a RADIATION BEAM to that with the object
removed from the beam, under specific measuring conditions
3.3.11.3
TRANSMISSION OF TOTAL RADIATION, T
t
characteristic of an object, evaluated as the ratio of the MEASURED VALUE of the quantity or
rate of total RADIATION with the object placed in a RADIATION BEAM to that with the object
removed from the beam, under specific measuring conditions
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60627 © IEC:2001 – 19 –
3.3.11.4
GRID SELECTIVITY, ΣΣΣΣ
characteristic of an ANTI-SCATTER GRID, evaluated as the ratio of the TRANSMISSION OF PRIMARY
RADIATION to the TRANSMISSION OF SCATTERED RADIATION, under specific measuring conditions
3.3.11.5
CONTRAST IMPROVEMENT RATIO, K
characteristic of an ANTI-SCATTER GRID, evaluated as the ratio of the TRANSMISSION OF PRIMARY
RADIATION to the TRANSMISSION OF TOTAL RADIATION, under specific measuring conditions
3.3.11.6
GRID EXPOSURE FACTOR, B
characteristic of an ANTI-SCATTER GRID, evaluated as the ratio of the MEASURED VALUE of the
quantity or rate of total RADIATION without the ANTI-SCATTER GRID in a RADIATION BEAM to that
with the ANTI-SCATTER GRID placed in the beam, under specific measuring conditions
3.3.12
Other terms
3.3.12.1
DECENTRING OF A FOCUSED GRID
distance from the FOCAL SPOT of an X-RAY TUBE to the plane through the TRUE CENTRAL LINE of
a FOCUSED GRID and perpendicular to the incident face of the grid
3.3.12.2
DEFOCUSING OF A FOCUSED GRID
difference between the distance from the FOCAL SPOT of an X-RAY TUBE to the incident face of
a FOCUSED GRID and the FOCUSING DISTANCE of that grid
4 Structure of ANTI-SCATTER GRIDS
ANTI-SCATTER GRIDS usually consist of strips of highly absorbent material, of thickness d and
height h, arranged at a regular distance D from each other; see figure 1.
The height h of the strips is either constant over the area of the ANTI-SCATTER GRID or
decreases in TAPERED GRIDS from the highest strip – with the height h – towards two edges.
o
NOTE D and d are measured at the incident face of the grid.
The interspaces between the strips are usually filled with highly transmitting material. The grid
may have a frame and covers to protect against mechanical damage, and to ensure the
rigidity of the device.
The STRIP FREQUENCY is defined as
1
N =
(d + D)
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60627 © IEC:2001 – 21 –
The GRID RATIO is
–for a PARALLEL GRID and for a FOCUSED GRID:
h
r =
D
–for a TAPERED GRID:
h
0
r =
0
D
–for a CROSS-GRID:
h
1
r =
1
D
1
h
2
r =
2
D
2
Letter symbols without index designate general properties of a LINEAR GRID. The index "0"
designates quantities at the TRUE CENTRAL LINE. Indices "1" or "2" designate quantities for the
LINEAR GRIDS forming a CROSS-GRID.
5 Measurement and determination of physical characteristics
5.1 Method and arrangement for measurement
5.1.1 Determination of physical characteristics
For the purpose of this standard, the values of the TRANSMISSION of X-RADIATION shall be
determined as the ratio of the two MEASURED VALUES obtained with the instrumentation
described in 5.1.2.
5.1.2 Instrumentation
A RADIATION DETECTOR shall be used which incorporates a FLUORESCENT SCREEN and a photo-
detector; see figure 2. The FLUORESCENT SCREEN shall be made from a calcium tungstate
phosphor, preferably without dye.
The area density of the phosphor shall be
–2 –2
a) for general purpose ANTI-SCATTER GRIDS 75 mg ⋅ cm ± 10 mg ⋅ cm ;
–2 –2
b) for
MAMMOGRAPHIC ANTI-SCATTER GRIDS 32 mg ⋅ cm ± 2 mg ⋅ cm .
The diameter of the measuring field shall be 6,0 mm ± 0,5 mm.
The luminance produced at the FLUORESCENT SCREEN shall be measured with the photo-
detector, preferably with a photomultiplier tube.
The ADDITIONAL FILTRATION between the supporting plane of the ANTI-SCATTER GRID and the
active layer of the FLUORESCENT SCREEN shall be not more than
a) for general purpose ANTI-SCATTER GRIDS 0,5 mm Al
b) for MAMMOGRAPHIC ANTI-SCATTER GRIDS 0,1 mm Al
in quality equivalent filtration for the radiation quality in use.
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60627 © IEC:2001 – 23 –
In order to ensure that the dark current and the direct IRRADIATION of the photo-detector do not
significantly affect the result of the measurements, the following check shall be made.
The arrangement shall be as described in 5.2.2 except that the PRIMARY RADIATION blocker
and the ANTI-SCATTER GRID are removed. The MEASURED VALUES of the detector signal shall be
obtained with the detector shielded against the light excited in the FLUORESCENT SCREEN, and
with the detector unshielded.
The ratio of these values shall not exceed 0,002.
NOTE A constant dark current of the RADIATION DETECTOR may be subtracted from the MEASURED VALUES.
5.1.3 PHANTOMS
a) For general purpose ANTI-SCATTER GRIDS, the PHANTOM used for the determination of
TRANSMISSION OF PRIMARY RADIATION and for the determination of TRANSMISSION OF
SCATTERED RADIATION shall be the PHANTOM described in 8.3 of IEC 61267. This PHANTOM
shall be a water-filled container. The container shall have
– sides of outside dimensions of 300 mm ± 1 mm and height of 200 mm ± 1 mm;
– top, bottom and walls made of polymethyl-methacrylate (PMMA) or of other material
having similar ATTENUATION properties, each being 10 mm ± 2 mm thick; and
– the interior
...
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