SIST EN 60789:2007
(Main)Medical electrical equipment - Characteristics and test conditions of radionuclide imaging devices - Anger type gamma cameras
Medical electrical equipment - Characteristics and test conditions of radionuclide imaging devices - Anger type gamma cameras
This International Standard specifies test methods for declaring the characteristics of Anger type GAMMA CAMERAS. The latter are composed of a collimator, a detector shield and a radiation detector assembly, together with recording and display devices. It is not within the scope of this standard to address the safety requirements to be followed by manufacturers according to IEC 60601-1.
Medizinische elektrische Geräte - Merkmale und Prüfbedingungen für bildgebende Systeme in der Nuklearmedizin - Einkristall-Gamma-Kameras
Appareils électromédicaux - Caractéristiques et conditions d'essai des dispositifs d'imagerie par radionucléides - Gamma caméras de type Anger
Spécifie les méthodes d'essai en vue d'annoncer les caractéristiques des gamma caméras de type Anger. Ces dernières sont constituées d'un collimateur, d'un blindage du détecteur et d'un ensemble détecteur de rayonnement associés à des dispositifs d'enregistrement et de visualisation. Les exigences de sécurité à suivre par les fabricants conformément à la EN 60601-1 ne rentrent pas dans le domaine d'application de la présente norme.
Medicinska električna oprema - Karakteristike in preskusni pogoji za naprave za slikanje z radionuklidi - Kamere z žarki gama tipa Anger (IEC 60789:2005)
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EUROPEAN STANDARD
EN 60789 NORME EUROPÉENNE EUROPÄISCHE NORM
December 2005 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 60789:2005 E
ICS 11.040.50 Supersedes EN 60789:1993
English version
Medical electrical equipment –
Characteristics and test conditions of radionuclide imaging devices - Anger type gamma cameras (IEC 60789:2005)
Appareils électromédicaux - Caractéristiques et conditions d'essai
des dispositifs d'imagerie
par radionucléides –
Gamma caméras de type Anger (CEI 60789:2005)
Medizinische elektrische Geräte - Merkmale und Prüfbedingungen für bildgebende Systeme in der Nuklearmedizin –
Einkristall-Gamma-Kameras (IEC 60789:2005)
This European Standard was approved by CENELEC on 2005-11-01. 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, 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.
EN 60789:2005 - 2 - Foreword The text of document 62C/388/FDIS, future edition 3 of IEC 60789, prepared by SC 62C, Equipment for radiotherapy, nuclear medicine and radiation dosimetry, of IEC TC 62, Electrical equipment in medical practice, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60789 on 2005-11-01. This European Standard supersedes EN 60789:1993. With respect to EN 60789:1993, the measurement of intrinsic point source sensitivity variation has been removed, the subclauses SYSTEM SENSITIVITY (4.2), SPATIAL RESOLUTION (4.3), NON-UNIFORMITY OF RESPONSE (4.5), INTRINSIC MULTIPLE WINDOW SPATIAL REGISTRATION (4.7) and COUNT RATE CHARACTERISTIC (4.8) have been reformulated (although the procedures are mostly unchanged) and some small editorial changes have been made. 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)
2006-08-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2008-11-01 In this standard the following print types are used: – requirements, compliance with which can be tested, and definitions: in roman type; – notes, explanations, advice, introductions, general statements, exceptions and reference: in smaller roman type; – test specifications: in italic type; – TERMS DEFINED IN CLAUSE 3 OF THIS STANDARD LISTED IN ANNEX B: SMALL CAPITALS. The requirements are followed by specifications for the relevant tests. Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 60789:2005 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60601-1 NOTE Harmonized as EN 60601-1:1990 (not modified).
IEC 61675-1 NOTE Harmonized as EN 61675-1:1998 (not modified).
IEC 61675-2 NOTE Harmonized as EN 61675-2:1998 (not modified). __________
- 3 - EN 60789:2005
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/TR 60788 2004 Medical electrical equipment -Glossary of defined terms
- -
NORME INTERNATIONALECEIIEC INTERNATIONAL STANDARD 60789Troisième éditionThird edition2005-10 Appareils électromédicaux – Caractéristiques et conditions d'essai des dispositifs d'imagerie par radionucléides – Gamma caméras de type Anger
Medical electrical equipment – Characteristics and test conditions of radionuclide imaging devices – Anger type gamma cameras
Pour prix, voir catalogue en vigueur For price, see current catalogue IEC 2005
Droits de reproduction réservés
Copyright - all rights reserved Aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit de l'éditeur. 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 the publisher. International Electrotechnical Commission,
3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, SwitzerlandTelephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch
Web: www.iec.ch CODE PRIX PRICE CODE U Commission Electrotechnique InternationaleInternational Electrotechnical Commission
60789 IEC:2005 – 3 – CONTENTS
FOREWORD.5 INTRODUCTION.9
1 Scope.11 2 Normative references.11 3 Terms and definitions.11 4 Test methods.17 4.1 General requirements.17 4.2 SYSTEM SENSITIVITY.17 4.3 SPATIAL RESOLUTION.21 4.4 SPATIAL NON-LINEARITY.25 4.5 NON-UNIFORMITY OF RESPONSE.27 4.6 INTRINSIC ENERGY RESOLUTION.31 4.7 INTRINSIC MULTIPLE WINDOW SPATIAL REGISTRATION.31 4.8 COUNT RATE CHARACTERISTIC.35 4.9 Shield leakage test.37 5 ACCOMPANYING DOCUMENTS.39
Bibliography.53 Index of defined terms.55
Figure 1 – Cuvette.39 Figure 2 – Cylindrical phantom.41 Figure 3 – Uniform source.41 Figure 4 – Slit phantom for measurement of intrinsic resolution and SPATIAL NON-LINEARITY.43 Figure 5 – Source arrangement for intrinsic measurements (4.3.5, 4.4.1, 4.5.4 and 4.6).45 Figure 6 – Small shielded liquid source.47 Figure 7 – Measurement of FWHM.49 Figure 8 – Evaluation of EQUIVALENT WIDTH (EW).51
Table 1 – Radionuclides and energy windows
to be used for performance measurements.17
60789 IEC:2005 – 5 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
MEDICAL ELECTRICAL EQUIPMENT – CHARACTERISTICS AND TEST CONDITIONS OF
RADIONUCLIDE IMAGING DEVICES –
ANGER TYPE GAMMA CAMERAS
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 60789 has been prepared by subcommittee 62C: Equipment for radiotherapy, nuclear medicine and radiation dosimetry, of IEC technical committee 62: Electrical equipment in medical practice. This third edition cancels and replaces the second edition published in 1992. It constitutes a technical revision. With respect to the second edition, the measurement of intrinsic point source sensitivity variation has been removed, the subclauses SYSTEM SENSITIVITY ( 4.2), SPATIAL RESOLUTION ( 4.3),NON-UNIFORMITY OF RESPONSE ( 4.5), INTRINSIC MULTIPLE WINDOW SPATIAL REGISTRATION ( 4.7) and COUNT RATE CHARACTERISTIC ( 4.8) have been reformulated (although the procedures are mostly unchanged) and some small editorial changes have been made.
60789 IEC:2005 – 7 – The text of this standard is based on the following documents: FDIS Report on voting 62C/388/FDIS 62C/392/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. In this standard the following print types are used: – requirements, compliance with which can be tested, and definitions: in roman type; – notes, explanations, advice, introductions, general statements, exceptions and reference: in smaller roman type; – test specifications: in italic type; – TERMS DEFINED IN CLAUSE 3 OF THIS STANDARD LISTED IN ANNEX B: SMALL CAPITALS.
The requirements are followed by specifications for the relevant tests. 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.
60789 IEC:2005 – 9 – INTRODUCTION The test methods specified in this standard have been selected to reflect as much as possible the clinical use of GAMMA CAMERAS. It is intended that the test methods be carried out by manufacturers, thereby enabling them to describe the characteristics of GAMMA CAMERAS on a common basis.
60789 IEC:2005 – 11 – MEDICAL ELECTRICAL EQUIPMENT – CHARACTERISTICS AND TEST CONDITIONS OF
RADIONUCLIDE IMAGING DEVICES –
ANGER TYPE GAMMA CAMERAS
1 Scope This International Standard specifies test methods for declaring the characteristics of Anger type GAMMA CAMERAS. The latter are composed of a collimator, a detector shield and a radiation detector assembly, together with recording and display devices. It is not within the scope of this standard to address the safety requirements to be followed by manufacturers according to IEC 60601-1. 2 Normative references The following referenced documents are 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 60788:2004, Medical electrical equipment – Glossary of defined terms 3 Terms and definitions For the purposes of this document, the definitions given in IEC 60788 (see Index of defined terms) and the following apply.
3.1
ENERGY WINDOW range defining the energy signals accepted by the device for further processing 3.2
DETECTOR FIELD OF VIEW FOV region of the detector within which events are included in the display image, and for which all performance specifications are provided
3.3
COLLIMATOR FRONT FACE surface of the COLLIMATOR which is closest to the object being imaged 3.4
COLLIMATOR BACK FACE surface of the COLLIMATOR which is closest to the RADIATION DETECTOR ASSEMBLY 3.5
ENTRANCE FIELD OF A COLLIMATOR area bounded by the shortest line which is tangential to the outside edges of the peripheral COLLIMATOR apertures on the COLLIMATOR FRONT FACE
60789 IEC:2005 – 13 – 3.6
EXIT FIELD OF A COLLIMATOR area bounded by the shortest line which is tangential to the outside edges of the peripheral COLLIMATOR apertures on the COLLIMATOR BACK FACE 3.7
COLLIMATOR AXIS straight line which passes through the geometrical centre of the EXIT and ENTRANCE FIELDS of the COLLIMATOR 3.8
PARALLEL HOLE COLLIMATOR COLLIMATOR with a number of apertures, the axes of which are parallel 3.9
PIN-HOLE COLLIMATOR COLLIMATOR with one small aperture in a plane in front of the RADIATION DETECTOR ASSEMBLY 3.10
ADDRESS PILE UP false address calculation of an artificial event which passes the ENERGY WINDOW, but is formed from two or more events by the PILE UP EFFECT 3.11
PILE UP EFFECT
false measurement of the pulse amplitude, due to the absorption of two or more gamma rays, reaching the same radiation detector within the RESOLVING TIME
[IEC 61675-1, definition 2.7.4.1] 3.12
SYSTEM SENSITIVITY with a specified COLLIMATOR and ENERGY WINDOW, the ratio of the COUNT RATE of the DETECTOR HEAD to the ACTIVITY of a plane source of specific dimensions and containing a specified radionuclide placed perpendicular to and centred on the COLLIMATOR AXIS under specified conditions NOTE See also Figure 2. 3.13
INTRINSIC LINE SPREAD FUNCTION line spread function measured with a collimated line source in front of the DETECTOR HEAD without COLLIMATOR 3.14
DETECTOR HEAD LINE SPREAD FUNCTION line spread function measured with an uncollimated line source at a specified distance Z from the COLLIMATOR FRONT FACE 3.15
EQUIVALENT WIDTH EW width of a rectangle having the same area as the LSF and a height equal to the maximum value of the LSF
60789 IEC:2005 – 15 – 3.16
SPATIAL RESOLUTION ability to concentrate the count density distribution in the image of a POINT SOURCE to a point
[IEC 61675-1, definition 2.4] 3.17
SYSTEM SPATIAL RESOLUTION SPATIAL RESOLUTION in a scattering medium for a specified COLLIMATOR, or a specified radionuclide, and at a specified distance from the COLLIMATOR FRONT FACE 3.18
INTRINSIC SPATIAL RESOLUTION SPATIAL RESOLUTION in air for a specified radionuclide excluding the COLLIMATOR 3.19
INTRINSIC ENERGY SPECTRUM measured histogram of pulse heights for the DETECTOR HEAD without COLLIMATOR NOTE The pulse height should be expressed as corresponding energy. 3.20
INTRINSIC ENERGY RESOLUTION FULL WIDTH AT HALF MAXIMUM of the full energy absorption peak in the INTRINSIC ENERGY SPECTRUM for a specified radionuclide 3.21
MULTIPLE WINDOW SPATIAL REGISTRATION measured position of a source as a function of the ENERGY WINDOW setting 3.22
INTRINSIC NON-UNIFORMITY OF RESPONSE NON-UNIFORMITY OF RESPONSE of the DETECTOR HEAD without COLLIMATOR 3.23
SYSTEM NON-UNIFORMITY OF RESPONSE NON-UNIFORMITY OF RESPONSE of the DETECTOR HEAD with COLLIMATOR 3.24
SPATIAL NON-LINEARITY deviations of the image of a straight line source from a straight line 3.25
INTRINSIC SPATIAL NON-LINEARITY SPATIAL NON-LINEARITY of the DETECTOR HEAD without COLLIMATOR 3.26
COUNT LOSS difference between measured COUNT RATE and TRUE COUNT RATE, which is caused by the finite RESOLVING TIME of the instrument [IEC 61675-1, definition 2.7.1]
60789 IEC:2005 – 17 – 3.27
COUNT RATE number of counts per unit of time [IEC 61675-1, definition 2.7.2] 4 Test methods 4.1 General requirements All measurements shall be performed with the energy window settings specified in Table 1. Table 1 – Radionuclides and energy windows
to be used for performance measurements Radionuclide Energy window
keV 99mTc 141, with a tolerance of ± 7,5 % 131I 364, with a tolerance of ± 10 % 67Ga 93, 184, 300,
with a tolerance of ± 20 % 68Ga 511, with a tolerance of ± 10 % NOTE Because the characteristics of a gamma camera may change noticeably between 122 keV (57Co) and 141 keV (99mTc), the former is not included as a suitable radionuclide. However, it may be useful in some circumstances, e.g. for quality control.
Additional measurements with other settings, as specified by the manufacturer, can be performed. Before the measurements are performed, the camera shall be adjusted by the procedure normally used by the manufacturer for an installed unit and shall not be adjusted specially for the measurement of specific parameters. Unless otherwise specified, measurements shall be carried out at count rates not exceeding 20 000 counts per second. 4.2 SYSTEM SENSITIVITY 4.2.1 General Sensitivity is a parameter that characterizes the effectiveness of a system to identify the radiation emitted from a RADIOACTIVE SOURCE, i.e. the rate at which events are detected in the presence of a RADIOACTIVE SOURCE in the limit of low ACTIVITY where COUNT LOSSES are negligible. The measured COUNT RATE for a given ACTIVITY and RADIONUCLIDE depends on many factors, including the detector material, its size and thickness, the size and shape of the RADIOACTIVE SOURCE including its absorption and scatter properties, and instruments dead time, energy thresholds and COLLIMATOR. 4.2.2 Purpose The purpose of this measurement is to determine the detected rate of events per unit of ACTIVITY for a standard volume source of given dimensions and a specified COLLIMATOR. 4.2.3 Method The SYSTEM SENSITIVITY test places a known amount of ACTIVITY of a specified RADIONUCLIDE within the DETECTOR FIELD OF VIEW of the GAMMA CAMERA and observes the resulting COUNT RATE. From these values the SYSTEM SENSITIVITY is calculated. The test is critically dependent
60789 IEC:2005 – 19 – upon accurate assays of RADIOACTIVITY as measured in a dose calibrator or well counter. It is difficult to maintain an absolute calibration with such devices to accuracies better than ±10 %. Absolute reference standards of the appropriate RADIONUCLIDE should be considered if higher degrees of accuracy are required. 4.2.4 Radionuclide The RADIONUCLIDE used for this measurement shall be appropriate for the COLLIMATOR design energy and chosen from Table 1.
4.2.5 RADIOACTIVE SOURCE The cylindrical phantom of polymethylmethacrylate as specified in Figure 2 shall be used. The source cuvette shown in Figure 1 shall be filled with the ACTIVITY and shall be placed in the cylindrical hole with the dimensions shown in Figure 2, the remainder of the hole shall then be filled by the cylindrical insert, the dimensions of which are also shown in Figure 2. The phantom, including the source, shall then be placed on the COLLIMATOR FRONT FACE (distance d = 0) and centred on the COLLIMATOR AXIS. NOTE Measurements of SYSTEM SENSITIVITY without scatter, using the source cuvette of Figure 1 placed at a distance of 10 cm from the COLLIMATOR FRONT FACE, may be carried out in addition to this test. 4.2.6 Data collection With an ENERGY WINDOW setting as specified in Table 1, at least 200 000 counts shall be acquired and the data acquisition time recorded to calculate the COUNT RATE Cs for all events collected in the image. 4.2.7 Data processing and analysis The ACTIVITY in the phantom shall be corrected for decay to determine the average ACTIVITY, Aave, during the data acquisition time interval, Tacq, by the following equation −−−=2lnexp12lnexp2ln2/1acq2/10calacq1/2calaveTTTTTTTAA where Acal is the ACTIVITY measured at time Tcal; T0 is the acquisition start time; T1/2 is the HALF LIFE of the RADIONUCLIDE. The SYSTEM SENSITIVITY S for the COLLIMATOR used shall then be found by aveACSs= and shall be expressed in counts s-1 ⋅ MBq-1. 4.2.8 Report Report the SYSTEM SENSITIVITY together with the COLLIMATOR and the RADIONUCLIDE used.
60789 IEC:2005 – 21 – 4.3 SPATIAL RESOLUTION 4.3.1 General SPATIAL RESOLUTION measurements describe partly the ability of an imaging system to reproduce the spatial distribution of a tracer in an object within an image. The measurement is performed by imaging LINE SOURCEs in air without COLLIMATOR (INTRINSIC SPATIAL RESOLUTION) and with COLLIMATOR using scattering material (SYSTEM SPATIAL RESOLUTION), respectively. The measurement of SYSTEM SPATIAL RESOLUTION including scatter is more representative of the clinical situation when measuring a patient, whereas the INTRINSIC SPATIAL RESOLUTION characterizes the DETECTOR HEAD performance excluding the COLLIMATOR. 4.3.2 Purpose The purpose of this measurement is to characterize the ability of the camera to resolve small objects by characterizing the width of the LINE SPREAD FUNCTIONs of radioactive LINE SOURCEs placed perpendicular to the direction of measurement at specified source-to-collimator distances. The width of the line spread function is measured by the FULL WIDTH AT HALF MAXIMUM (FWHM) and the EQUIVALENT WIDTH (EW). 4.3.3 Method For all systems, the SPATIAL RESOLUTION shall be measured in IMAGE PLANES parallel to the COLLIMATOR FRONT FACE. The FIELD OF VIEW and the IMAGE MATRIX size determine the PIXEL size in the IMAGE PLANE. In order to accurately measure the width of the LINE SPREAD FUNCTION, its FWHM should span at least ten PIXELs in the test image. The width of the response may be incorrect if there are fewer than ten PIXELs in the FWHM. Therefore, if possible, the PIXEL size should be made close to one-tenth of the expected FWHM and should be indicated as ancillary data for the SPATIAL RESOLUTION measurement 4.3.4 Radionuclide For the measurement of SYSTEM SPATIAL RESOLUTION the radionuclide for the measurement shall be chosen from Table 1 according to the collimator used. For the measurement of INTRINSIC SPATIAL RESOLUTION the radionuclide shall be 99mTc. 4.3.5 Radioactive source distribution For the measurement of SYSTEM SPATIAL RESOLUTION, a LINE SOURCE shall be prepared by placing a solution containing the selected RADIONUCLIDE in a tube with an inner diameter of 1 mm and covering the length of the DETECTOR FIELD OF VIEW along the major axis. For the measurement of INTRINSIC SPATIAL RESOLUTION, a multiple slit transmission phantom shall be used as shown in Figure 4. The slit transmission phantom covering the entire FIELD OF VIEW shall be placed at the centre of the detector face (COLLIMATOR removed).
A collimated source shall be positioned vertically above the centre of the phantom at a distance of at least five times the maximum linear dimension of the FIELD OF VIEW (Figure 5).
60789 IEC:2005 – 23 – 4.3.6 Measurement of SPATIAL RESOLUTION 4.3.6.1 SYSTEM SPATIAL RESOLUTION (with scatter) The GAMMA CAMERA shall be equipped with the COLLIMATOR under study. The LINE SOURCE shall be placed with its axis perpendicular to the COLLIMATOR AXIS and aligned parallel to one of the electronic axes at the depth of measurement in water or water-equivalent material covering the whole FIELD OF VIEW. The air gap between the COLLIMATOR FRONT FACE and the surface of the scattering medium shall be less than 5 mm. The depth of the scattering medium along the COLLIMATOR AXIS shall be 200 mm in total. The measurement shall be carried out in three parallel planes with the centre of the source at 50 mm, 100 mm and 150 mm from the COLLIMATOR FRONT FACE. The measurement shall be repeated with the source aligned parallel to the other electronic axis. Data shall be acquired with a pixel size equal to or less than 10 % of the FWHM at the depth of measurement. At least 10 000 counts shall be collected in the peak point of each LINE SPREAD FUNCTION. 4.3.6.2 INTRINSIC SPATIAL RESOLUTION The slit transmission phantom shall be placed on the GAMMA CAMERA, with the COLLIMATOR removed. The orientation of the slit transmission phantom shall be adjusted until its slit axis is aligned parallel to the X- or Y-electronic axis. Two sets of data shall be obtained. At least 1 000 counts shall be collected in the peak point of each LINE SPREAD FUNCTION. 4.3.7 Data processing 4.3.7.1 Data processing for SYSTEM SPATIAL RESOLUTION The SYSTEM SPATIAL RESOLUTION profiles of width 30 mm ± 5 mm shall be obtained at right angles to the LINE SOURCE. The lateral extension of profiles shall be to a point where the measured quantity is 5 % of the maximum value, or up to the edge of the DETECTOR FIELD OF VIEW, whichever lateral extension is the smaller. The profiles shall abut each other. 4.3.7.2 Data processing for INTRINSIC SPATIAL RESOLUTION For the INTRINSIC SPATIAL RESOLUTION profiles of width 30 mm ± 5 mm shall be obtained at right angles to the direction of the slit. The profiles shall abut each other. 4.3.8 Data analysis FULL WIDTH AT HALF MAXIMUM (FWHM) shall be determined by linear interpolation between adjacent PIXELS at half the maximum PIXEL value, which is the peak of the response function (see Figure 7). Values shall be converted to millimetre units by multiplication with the appropriate PIXEL size. EQUIVALENT WIDTH EW shall be measured from the corresponding response function. EW is calculated from the formula (see Figure 8) ∑×=iiCPWCEWm where ∑iiC is the sum of the counts in the profile between the limits defined by 1/20 mC on either side of the peak;
60789 IEC:2005 – 25 – mC
is the maximum PI
...
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