Medical electrical equipment - X-ray tube assemblies for medical diagnosis - Characteristics of focal spots

This International Standard applies to focal spots in medical diagnostic x-ray tube assemblies for medical use, operating at x-ray tube voltages up to and including 200 kV. This International Standard describes the test methods for evaluating focal spot characteristics and the means for indicating compliance.

Medizinische elektrische Geräte - Röntgenstrahler für medizinische Diagnostik - Kennwerte von Brennflecken

Appareils électromédicaux - Gaines équipées pour diagnostic médical - Caractéristiques des foyers

S'applique aux foyers des gaines équipées à usage médical, pour diagnostic médical, fonctionnant à des potentiels d'accélération de tubes radiogènes inférieurs ou égaux à 200 kV. Décrit les méthodes d'essai pour l'évaluation des caractéristiques des foyers et les moyens d'indiquer la conformité.

Medicinska električna oprema – Rentgenske naprave za medicinsko diagnostiko – Značilnosti žariščnih točk (IEC 60336:2005)

General Information

Status
Published
Publication Date
31-Dec-2005
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Jan-2006
Due Date
01-Jan-2006
Completion Date
01-Jan-2006

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SLOVENSKI SIST EN 60336:2006
STANDARD
januar 2006
Medicinska električna oprema – Rentgenske naprave za medicinsko
diagnostiko – Značilnosti žariščnih točk (IEC 60336:2005)
(istoveten EN 60336:2005)
Medical electrical equipment - X-ray tube assemblies for medical diagnosis -
Characteristics of focal spots (IEC 60336:2005)
ICS 11.040.50; 11.040.55 Referenčna številka
SIST EN 60336:2006(en)

© Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD EN 60336
NORME EUROPÉENNE
EUROPÄISCHE NORM July 2005
ICS 11.040.50 Supersedes EN 60336:1995
English version
Medical electrical equipment –
X-ray tube assemblies for medical diagnosis –
Characteristics of focal spots
(IEC 60336:2005)
Appareils électromédicaux – Medizinische elektrische Geräte -
Gaines équipées pour diagnostic médical - Röntgenstrahler für medizinische
Caractéristiques des foyers Diagnostik –
(CEI 60336:2005) Kennwerte von Brennflecken
(IEC 60336:2005)

This European Standard was approved by CENELEC on 2005-06-01. 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, Cyprus, Czech

Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, 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

© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 60336:2005 E
---------------------- Page: 2 ----------------------
EN 60336:2005 - 2 -
Foreword

The text of document 62B/554/FDIS, future edition 4 of IEC 60336, 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 60336 on 2005-06-01.
This European Standard supersedes EN 60336:1995.
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) 2006-03-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2008-06-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 60336:2005 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following note has to be added for the standard indicated:

IEC 60601-2-28 NOTE Harmonized as EN 60601-2-28:1993 (not modified).
__________
---------------------- Page: 3 ----------------------
- 3 - EN 60336:2005
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE Where 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 database Graphical symbols for use on - -
equipment
1) 2)
IEC 60613 - Electrical, thermal and loading EN 60613 1990
characteristics of rotating anode X-ray
tubes for medical diagnosis
IEC/TR 60788 2004 Medical electrical equipment - - -
Glossary of defined terms
Undated reference.
Valid edition at date of issue.
---------------------- Page: 4 ----------------------
NORME CEI
INTERNATIONALE
IEC
60336
INTERNATIONAL
Quatrième édition
STANDARD
Fourth edition
2005-04
Appareils électromédicaux –
Gaines équipées pour diagnostic médical –
Caractéristiques des foyers
Medical electrical equipment –
X-ray tube assemblies for medical diagnosis –
Characteristics of focal spots
 IEC 2005 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 any

utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including

électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from

microfilms, sans l'accord écrit de l'éditeur. the publisher.

International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland

Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch

CODE PRIX
PRICE CODE
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue
---------------------- Page: 5 ----------------------
60336  IEC:2005 – 3 –
CONTENTS

FOREWORD...........................................................................................................................7

1 Scope.............................................................................................................................11

2 Normative references .....................................................................................................11

3 Terms and definitions .....................................................................................................11

4 Determinations for the evaluation of the FOCAL SPOT characteristics................................11

4.1 Statement of the FOCAL SPOT characteristics ..........................................................11

4.2 Longitudinal axis of the X-RAY TUBE ASSEMBLY........................................................11

4.3 REFERENCE AXIS of the X-RAY TUBE ASSEMBLY .........................................................13

4.4 Direction of evaluation for the FOCAL SPOT length...................................................13

4.5 Direction of evaluation for the FOCAL SPOT width ....................................................13

5 FOCAL SPOT camera set-up ..............................................................................................13

5.1 Overview ...............................................................................................................13

5.2 Test equipment .....................................................................................................13

5.3 Test arrangement ..................................................................................................17

5.4 Total uncertainty of the camera set-up ..................................................................23

6 Production of RADIOGRAMS ..............................................................................................23

6.1 Overview ...............................................................................................................23

6.2 Operating conditions .............................................................................................23

6.3 Production of FOCAL SPOT SLIT RADIOGRAMS or FOCAL SPOT PINHOLE

RADIOGRAMS...........................................................................................................25

6.4 Statement of compliance .......................................................................................27

7 Determination of the LINE SPREAD FUNCTION.....................................................................27

7.1 Overview ...............................................................................................................27

7.2 Measuring equipment and measuring arrangement................................................27

7.3 Measurement of the density distribution ................................................................29

7.4 Determination of the LINE SPREAD FUNCTION ...........................................................29

7.5 Statement of compliance .......................................................................................29

8 Determination of FOCAL SPOT dimensions........................................................................31

8.1 Overview ...............................................................................................................31

8.2 Measurement and determination ...........................................................................31

8.3 Specified NOMINAL FOCAL SPOT VALUES ...................................................................33

8.4 Statement of compliance .......................................................................................37

8.5 Marking of compliance...........................................................................................37

9 Determination of the MODULATION TRANSFER FUNCTION .....................................................37

9.1 Overview ...............................................................................................................37

9.2 Specified MODULATION TRANSFER FUNCTION.............................................................37

9.3 Calculation of the MODULATION TRANSFER FUNCTION ................................................39

9.4 Evaluation of compliance of the MTF.....................................................................41

9.5 Statement of compliance .......................................................................................41

10 FOCAL SPOT STAR RADIOGRAMS.........................................................................................41

10.1 Overview ...............................................................................................................41

10.2 Test equipment .....................................................................................................43

11 STAR PATTERN RESOLUTION LIMIT ......................................................................................47

11.1 Overview ...............................................................................................................47

---------------------- Page: 6 ----------------------
60336  IEC:2005 – 5 –

11.2 Specified STAR PATTERN RESOLUTION LIMIT ..............................................................47

11.3 Measurement ........................................................................................................49

11.4 Determination of the STAR PATTERN RESOLUTION LIMIT .............................................49

11.5 Evaluation and statement of compliance................................................................51

12 BLOOMING VALUE..............................................................................................................53

12.1 Overview ...............................................................................................................53

12.2 Determination of the BLOOMING VALUE ....................................................................53

12.3 Evaluation and statement of compliance................................................................53

13 Alternate measurement methods ....................................................................................55

Annex A (informative) Alignment to the REFERENCE AXIS.......................................................57

Annex B (informative) Application of digital X-ray image detectors for determination of

the FOCAL SPOT characteristics ..............................................................................................61

Annex C (informative) Historical background........................................................................63

Bibliography..........................................................................................................................73

Index of defined terms ..........................................................................................................75

Figure 1 – Essential dimensions of the slit diaphragm...........................................................15

Figure 2 – Essential dimensions of the pinhole diaphragm ....................................................17

Figure 3 − Position of the centre of the slit or pinhole diaphragm (marked as x in the

figure) with respect to the REFERENCE AXIS ............................................................................19

Figure 4 – Reference dimensions and planes........................................................................21

Figure 5 − Alignment of the optical densitometer slit .............................................................29

Figure 6 – LINE SPREAD FUNCTION...........................................................................................31

Figure 7 – Essential dimensions of the star test pattern ........................................................43

Figure 8 – Essential dimensions of the star test pattern ........................................................45

Figure 9 – Illustration of the zones of minimum modulation ...................................................49

Figure A.1 – The REFERENCE AXIS and directions of evaluation ..............................................57

Figure A.2 – Projection of the ACTUAL FOCAL SPOT on the IMAGE RECEPTION PLANE..................59

Figure C.1 – The LSFs for a typical X-RAY TUBE with small FOCAL SPOT (< 0,3 mm) ...............65

Figure C.2 – The LSFs for a typical X-RAY TUBE with large FOCAL SPOT (≥0,3 mm).................65

Figure C.3 – The corresponding MTFs for the LSFs in Figure C.2 .........................................67

Table 1 – Enlargement for FOCAL SPOT RADIOGRAMs ..............................................................23

Table 2 − LOADING FACTORS ..................................................................................................25

Table 3 − Maximum permissible values of FOCAL SPOT dimensions for NOMINAL FOCAL

SPOT VALUES..........................................................................................................................35

Table 4 − Standard magnifications for MODULATION TRANSFER FUNCTIONS...............................39

Table 5 – Standard magnifications for STAR PATTERN RESOLUTION LIMIT..................................51

Table 6 – LOADING FACTORS for the determination of the BLOOMING VALUE..............................53

Table C.1 − Methods for evaluation of specific aspects characterising the FOCAL SPOT..........71

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60336  IEC:2005 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL EQUIPMENT –
X-RAY TUBE ASSEMBLIES FOR MEDICAL DIAGNOSIS –
CHARACTERISTICS OF FOCAL SPOTS
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of 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, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). 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. 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 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 IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 60336 has been prepared by subcommittee 62B: Diagnostic

imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.

This fourth edition cancels and replaces the third edition published in 1993 and constitutes a

technical revision. The significant changes of this fourth edition are detailed in Annex C (see

Clause C.6).
The text of this standard is based on the following documents:
FDIS Report on voting
62B/554/FDIS 62B/569/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.
---------------------- Page: 8 ----------------------
60336  IEC:2005 – 9 –

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

In this standard, the following conventions apply.

a) Terms printed in small capitals are used as defined in IEC 60788 and in Clause 3 of this

standard. Where a defined term is used as a qualifier in another defined or undefined

term, it is not printed in small capitals, unless the concept thus qualified is defined or

recognized as a “derived term without definition”.

b) Certain terms that are not printed in small capitals have particular meanings, as follows

− "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 purposes, or the parameters or
conditions associated with its use or with testing to determine compliance.

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.

The committee has decided that the contents of this publication will remain unchanged until

the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in

the data related to the specific publication. At this date, the publication will be

• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of May 2006 have been included in this copy.
---------------------- Page: 9 ----------------------
60336  IEC:2005 – 11 –
MEDICAL ELECTRICAL EQUIPMENT –
X-RAY TUBE ASSEMBLIES FOR MEDICAL DIAGNOSIS –
CHARACTERISTICS OF FOCAL SPOTS
1 Scope

This International Standard applies to FOCAL SPOTs in medical diagnostic X-RAY TUBE

assemblies for medical use, operating at X-RAY TUBE VOLTAGEs up to and including 200 kV.

This International Standard describes the test methods for evaluating FOCAL SPOT character-

istics and the means for indicating compliance.
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-DB:2002: Graphical symbols for use on equipment

IEC 60613, Electrical, thermal and loading characteristics of rotating anode X-ray tubes for

medical diagnosis
IEC 60788:2004, Medical electrical equipment – Glossary of defined terms
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60788 together with

the following apply.
3.1
STAR PATTERN RESOLUTION LIMIT

characteristic of the FOCAL SPOT of an X-RAY TUBE; highest spatial frequency that can be

resolved under specific measuring conditions
4 Determinations for the evaluation of the FOCAL SPOT characteristics
4.1 Statement of the FOCAL SPOT characteristics

The FOCAL SPOT characteristics shall be stated for two normal directions of evaluation referred

to as the length direction and width direction. An illustration for this clause can be found in

Figure A.1.
4.2 Longitudinal axis of the X-RAY TUBE ASSEMBLY

Generally, the longitudinal axis can be identified unambiguously. If the X-RAY TUBE ASSEMBLY

does not have an identifiable longitudinal axis or if it is specified otherwise by the

MANUFACTURER, the longitudinal axis shall be specified together with the FOCAL SPOT

characteristics.
———————
"DB" refers to the IEC on-line database.
---------------------- Page: 10 ----------------------
60336  IEC:2005 – 13 –
4.3 REFERENCE AXIS of the X-RAY TUBE ASSEMBLY

If not specified otherwise, the REFERENCE AXIS is normal to the longitudinal axis and intersects

both the centre of the ACTUAL FOCAL SPOT and the longitudinal axis of the X-RAY TUBE

ASSEMBLY.
4.4 Direction of evaluation for the FOCAL SPOT length

The direction of evaluation for the FOCAL SPOT length is normal to the REFERENCE AXIS in the

plane given by the REFERENCE AXIS and the longitudinal axis of the X-RAY TUBE ASSEMBLY.

4.5 Direction of evaluation for the FOCAL SPOT width

The direction of evaluation for the FOCAL SPOT width is normal to the longitudinal axis of the X-

RAY TUBE ASSEMBLY and normal to the REFERENCE AXIS.
5 FOCAL SPOT camera set-up
5.1 Overview

This clause deals with the design requirements of a camera for the production of FOCAL SPOT

SLIT RADIOGRAMs to be used for the determination of FOCAL SPOT dimensions in accordance

with Clause 8, and the determination of the modulation transfer function in accordance with

Clause 9.

This clause deals also with the design requirements of a camera for the production of FOCAL

SPOT PINHOLE RADIOGRAMs.
5.2 Test equipment
5.2.1 SLIT CAMERA

The diaphragm of the SLIT CAMERA shall be made from materials with high ATTENUATION

properties and shall have dimensions as given in Figure 1.
Suitable materials are for example:
– tungsten;
– tantalum;
– alloy of gold and 10 % platinum;
– alloy of tungsten and 10 % rhenium;
– alloy of platinum and 10 % iridium;
---------------------- Page: 11 ----------------------
60336  IEC:2005 – 15 –
Dimensions in millimetres
Not drawn to scale
Axis of symmetry
0,01 ± 0,002
8° ± 1°
≥ 5
0,002
// 0,002
IEC 526/05
Figure 1 – Essential dimensions of the slit diaphragm
≥ 1,5
≤ 0,015
≥ 5
---------------------- Page: 12 ----------------------
60336  IEC:2005 – 17 –
5.2.2 PINHOLE CAMERA

The diaphragm of the PINHOLE CAMERA shall be constructed from materials with high

ATTENUATION and shall have dimensions as given in Figure 2.
Suitable materials are for example:
– tungsten;
– tantalum;
– alloy of gold and 10 % platinum;
– alloy of tungsten and 10 % rhenium;
– alloy of platinum and 10 % iridium.
Dimensions in millimetres
Not drawn to scale
Axis of symmetry
0,03 ± 0,005
8° ± 1°
≥ 5
IEC 527/05
Figure 2 – Essential dimensions of the pinhole diaphragm
5.2.3 RADIOGRAPHIC FILM

FOCAL SPOT SLIT RADIOGRAMS or FOCAL SPOT PINHOLE RADIOGRAMS shall be made using fine-

grain radiographic film, for example dental radiographic film, without INTENSIFYING SCREENS.

5.3 Test arrangement
5.3.1 Position of the slit or pinhole diaphragm normal to the REFERENCE AXIS

The slit or pinhole diaphragm shall be positioned in such a way that the distance from its

centre to the REFERENCE AXIS is within 0,2 mm per 100 mm of m (as indicated in Figure 3).

≥ 1,5
≤ 0,075
---------------------- Page: 13 ----------------------
60336  IEC:2005 – 19 –
EFFECTIVE FOCAL SPOT
REFERENCE PLANE
(100 mm min.)
REFERENCE AXIS
Incident face of the slit
or pinhole diaphragm
∅0,4 per
100 mm
Centre of diaphragm
IMAGE RECEPTION PLANE
IEC 528/05
Figure 3 − Position of the centre of the slit or pinhole diaphragm (marked as x
in the figure) with respect to the REFERENCE AXIS
5.3.2 Position of the slit or pinhole diaphragm along the REFERENCE AXIS

The incident face of the slit or pinhole diaphragm shall be placed at a distance from the

REFERENCE PLANE sufficient to ensure that the variation of the enlargement over the extension

of the ACTUAL FOCAL SPOT does not exceed ± 5 % along the REFERENCE AXIS (see Figure 4).

This is met when
p < 5 mm and k < 5 mm per 100 mm of distance m;
where

k is the distance from the REFERENCE PLANE to the edge of the ACTUAL FOCAL SPOT farthest

away from the slit or pinhole diaphragm;

p is the distance from the REFERENCE PLANE to the edge of the ACTUAL FOCAL SPOT closest to

the slit or pinhole diaphragm;

m is the distance from the REFERENCE PLANE to the incident face of the diaphragm;

n is the distance from the incident face of the diaphragm to the IMAGE RECEPTION PLANE;

E is the enlargement given by n/m .

The distance from the FOCAL SPOT to the slit or pinhole diaphragm shall not be less than

100 mm.
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60336  IEC:2005 – 21 –
EFFECTIVE FOCAL SPOT
REFERENCE PLANE
Incident face of the slit
or pinhole diaphragm
REFERENCE AXIS
IMAGE RECEPTION PLANE
IEC 529/05
Figure 4 – Reference dimensions and planes
5.3.3 Orientation of the slit or pinhole diaphragm

The axis of symmetry (see Figures 1 and 2) shall be aligned with the REFERENCE AXIS forming

an angle that is smaller than 1° .

For the production of a pair of FOCAL SPOT SLIT RADIOGRAMs, the slit diaphragm shall be

orientated such that the length of the slit is normal to the direction of evaluation within ±1°.

5.3.4 Position of the RADIOGRAPHIC FILM

The RADIOGRAPHIC FILM should be placed in the IMAGE RECEPTION PLANE normal to the

REFERENCE AXIS within ±1° and at a distance from the incident face of the slit or pinhole

diaphragm determined from the appropriate enlargement according to Table 1. The
enlargement E shall be determined with an accuracy to within ±3 %.
---------------------- Page: 15 ----------------------
60336  IEC:2005 – 23 –
Table 1 – Enlargement for FOCAL SPOT RADIOGRAMs
Enlargement
NOMINAL FOCAL SPOT VALUE (f)
(E = n / m)
f < 0,4 E > 3
0,4 < f < 1,1 E > 2
1,1 < f E ≥ 1
See 8.3.
See Figure 4.
5.4 Total uncertainty of the camera set-up

The uncertainty in the FOCAL SPOT measurement contributed by the set-up of the FOCAL SPOT

camera shall not exceed ±5 %.
6 Production of RADIOGRAMS
6.1 Overview

This clause deals with production of FOCAL SPOT SLIT RADIOGRAMS and FOCAL SPOT PINHOLE

RADIOGRAMS.

A method of indicating compliance with this standard of FOCAL SPOT SLIT RADIOGRAMS and

FOCAL SPOT PINHOLE RADIOGRAMS is included.
6.2 Operating conditions
6.2.1 FOCAL SPOT SLIT RADIOGRAMS and FOCAL SPOT PINHOLE RADIOGRAMS

FOCAL SPOT SLIT RADIOGRAMS and FOCAL SPOT PINHOLE RADIOGRAMS shall be produced using a

FOCAL SPOT camera according to Cl
...

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