IEC 61675-2:2015

IEC 61675-2 ®
Edition 2.0 2015-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Radionuclide imaging devices – Characteristics and test conditions –
Part 2: Gamma cameras for planar, wholebody, and SPECT imaging

Dispositifs d’imagerie par radionucléides – Caractéristiques et conditions
d’essai –
Partie 2: Gamma-caméras pour l'imagerie planaire, l'imagerie du corps entier et
l'imagerie SPECT
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IEC 61675-2 ®
Edition 2.0 2015-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Radionuclide imaging devices – Characteristics and test conditions –

Part 2: Gamma cameras for planar, wholebody, and SPECT imaging

Dispositifs d’imagerie par radionucléides – Caractéristiques et conditions

d’essai –
Partie 2: Gamma-caméras pour l'imagerie planaire, l'imagerie du corps entier et

l'imagerie SPECT
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 11.040.50 ISBN 978-2-8322-2819-7

– 2 – IEC 61675-2:2015 © IEC 2015
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions. 7
4 Test methods . 15
4.1 General . 15
4.2 Planar imaging . 16
4.2.1 SYSTEM SENSITIVITY . 16
4.2.2 SPATIAL RESOLUTION . 18
4.2.3 SPATIAL NON-LINEARITY. 24
4.2.4 NON-UNIFORMITY OF RESPONSE . 25
4.2.5 INTRINSIC ENERGY RESOLUTION . 28
4.2.6 Intrinsic MULTIPLE WINDOW SPATIAL REGISTRATION . 29
4.2.7 COUNT RATE performance . 31
4.2.8 Shield leakage test . 33
4.3 Wholebody imaging . 33
4.3.1 Scanning constancy . 33
4.3.2 SPATIAL RESOLUTION without scatter . 36
4.4 Tomographic imaging (SPECT) . 37
4.4.1 Test of PROJECTION geometry . 37
4.4.2 Measurement of SPECT SYSTEM SENSITIVITY . 41
4.4.3 Scatter measurement . 44
4.4.4 SPECT SYSTEM SPATIAL RESOLUTION . 48
4.4.5 Tomographic image quality . 50
5 Accompanying documents . 57
5.1 General . 57
5.2 General parameters for GAMMA CAMERAS . 58
5.2.1 COLLIMATORS . 58
5.2.2 Shield leakage values . 58
5.2.3 Pre-set PULSE AMPLITUDE ANALYSER WINDOWS . 58
5.2.4 INTRINSIC ENERGY RESOLUTION . 58
5.2.5 COLLIMATOR dependent quantities . 58
5.2.6 COUNT RATE CHARACTERISTICS . 58
5.2.7 Measured COUNT RATE that is 80 % of the corresponding TRUE COUNT
RATE . 58
5.2.8 Dimensions of the DETECTOR FIELD OF VIEW . 58
5.2.9 Non-uniformity characteristics . 58
5.2.10 INTRINSIC SPATIAL RESOLUTION (FWHM and EW) of the DETECTOR HEAD
COLLIMATOR . 58
without
5.2.11 INTRINSIC SPATIAL NON-LINEARITY . 58
5.2.12 Intrinsic MULTIPLE WINDOW SPATIAL REGISTRATION . 59
5.3 GAMMA CAMERA based wholebody imaging system . 59
5.3.1 Scanning constancy . 59
5.3.2 SPATIAL RESOLUTION . 59
5.4 SPECT . 59

5.4.1 Calibration measurements of COR . 59
5.4.2 Measurement of head tilt . 59
5.4.3 Measurement of COLLIMATOR hole misalignment . 59
5.4.4 TRANSVERSE RESOLUTION (radial and tangential) . 59
5.4.5 AXIAL RESOLUTION . 59
5.4.6 Axial PIXEL size . 59
5.4.7 Transaxial PIXEL size . 59
5.4.8 DETECTOR POSITIONING TIME . 59
5.4.9 NORMALIZED VOLUME SENSITIVITY . 59
5.4.10 SCATTER FRACTIONS SF and SF . 59
i
5.4.11 Scan set up and phantom ACTIVITY concentration . 59
5.4.12 Image quality . 59
5.4.13 Accuracy of ATTENUATION correction and scatter correction . 59
5.4.14 Accuracy of SPECT and CT image registration . 59
Index of defined terms . 60
Bibliography . 62

Figure 1 – Geometry of PROJECTIONS . 9
Figure 2 – Cylindrical phantom . 14
Figure 3 – Cuvette . 17
Figure 4 – Slit phantom . 19
Figure 5 – Source arrangement for intrinsic measurements . 20
Figure 6 – Calculation of FWHM . 22
Figure 7 – Evaluation of equivalent width (EW) . 23
Figure 8 – Uniform source . 26
Figure 9 – Small shielded liquid source . 29
Figure 10 – Source positions for scanning constancy for wholebody imaging . 35
Figure 11 – Cylindrical phantom . 43
Figure 12 – Phantom insert with holders for the scatter source . 45
Figure 13 – Evaluation of scatter fraction . 47
Figure 14 – Reporting transverse resolution . 49
Figure 15 – Cross-section of body phantom . 51
Figure 16 – Phantom insert with hollow spheres . 52
Figure 17 – Placement of ROIs in the phantom background . 55

Table 1 – RADIONUCLIDES and ENERGY WINDOWS to be used for performance
measurements . 16

– 4 – IEC 61675-2:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RADIONUCLIDE IMAGING DEVICES –
CHARACTERISTICS AND TEST CONDITIONS –

Part 2: Gamma cameras for planar, wholebody,
and SPECT imaging
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
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6) All users should ensure that they have the latest edition of this publication.
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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 61675-2 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 second edition of IEC 61675-2 cancels and replaces the first edition published in 1998 and
its Amendment 1 published in 2004, as well as IEC 60789:2005, IEC 60789:2005/COR1:2009,
and IEC 61675-3:1998. It has been reformatted, updated, and partly aligned with NEMA NU 1-
2007. Due to the lack of market share of SPECT-systems operated in coincidence mode all
such tests have been removed.
The text of this standard is based on the following documents:
FDIS Report on voting
62C/616/FDIS 62C/623/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:
– TERMS DEFINED IN CLAUSE 2 OF THIS STANDARD OR LISTED IN THE INDEX OF DEFINED TERMS:
SMALL CAPITALS.
The requirements are followed by specifications for the relevant tests.
Annex A is for information only.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC website 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.
– 6 – IEC 61675-2:2015 © IEC 2015
INTRODUCTION
The test methods specified in this part of IEC 61675 have been selected to reflect as much as
possible the clinical use of GAMMA CAMERAS for planar imaging, PLANAR WHOLEBODY IMAGING
EQUIPMENT, and SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY (SPECT). It is intended that
the test methods are carried out by manufacturers thereby enabling them to describe the
characteristics of the systems on a common basis.

RADIONUCLIDE IMAGING DEVICES –
CHARACTERISTICS AND TEST CONDITIONS –

Part 2: Gamma cameras for planar, wholebody,
and SPECT imaging
1 Scope
This part of IEC 61675 specifies terminology and test methods for describing the character-
istics of GAMMA CAMERAS equipped with PARALLEL HOLE COLLIMATORS for planar imaging.
Additional tests are specified for those GAMMA CAMERAS that are capable of planar wholebody
imaging (PLANAR WHOLEBODY IMAGING EQUIPMENT) or SINGLE PHOTON EMISSION COMPUTED
TOMOGRAPHY (SPECT). These GAMMA CAMERAS consist of a gantry, single or multiple DETECTOR
HEADS, and a computer for data acquisition, processing, storage, and display. The DETECTOR
HEADS may contain single or multiple scintillation crystals or solid state detectors.
No test has been specified to characterize the uniformity of reconstructed images because all
methods known so far will mostly reflect the noise of the image.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. 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
IEC 61675-1:2013, Radionuclide imaging devices – Characteristics and test conditions –
Part 1: Positron emission tomographs
3 Terms and definitions
For the purposes of this document the terms and definitions given in IEC 60788 and
IEC 61675-1 (some of which are repeated here for convenience), and the following terms and
definitions apply.
3.1
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
3.2
AXIAL FIELD OF VIEW
dimensions of a slice through the TOMOGRAPHIC VOLUME parallel to and including the SYSTEM
AXIS
Note 1 to entry: In practice it is specified only by its axial dimension given by the distance between the centres of
the outermost defined IMAGE PLANES plus the average of the measured AXIAL SLICE WIDTH measured as EQUIVALENT
WIDTH (EW).
– 8 – IEC 61675-2:2015 © IEC 2015
3.3
AXIAL RESOLUTION
for tomographs with sufficiently fine axial sampling fulfilling the sampling theorem, SPATIAL
RESOLUTION along a line parallel to the SYSTEM AXIS
3.4
CENTRE OF ROTATION
COR
origin of that coordinate system, which describes the PROJECTIONS of a transverse slice with
respect to their orientation in space
Note 1 to entry: The CENTRE OF ROTATION of a transverse slice is given by the intersection of the SYSTEM AXIS with
the mid-plane of the corresponding OBJECT SLICE.
Note 2 to entry: The second note to entry concerns the French text only.
3.5
COLLIMATOR AXIS
straight line which passes through the geometrical centre of the exit field and entrance field of
the COLLIMATOR
3.6
COLLIMATOR FRONT FACE
surface of the COLLIMATOR which is closest to the object being imaged
3.7
COORDINATE SYSTEM OF PROJECTION
Cartesian system of the IMAGE MATRIX of each two-dimensional PROJECTION with axes X and
p
Y
p
Note 1 to entry: Axes X and Y are defined by the axes of the IMAGE MATRIX.
p p
Note 2 to entry: The Y axis and the PROJECTION of the SYSTEM AXIS onto the detector front face have to be in
p
parallel.
Note 3 to entry: The origin of the COORDINATE SYSTEM OF PROJECTION may be the centre of the IMAGE MATRIX (see
Figure 1).
IEC
NOTE The FIXED COORDINATE SYSTEM X, Y, Z has its origin at the centre of the TOMOGRAPHIC VOLUME (shown as a
cylinder), the Z-axis being the SYSTEM AXIS. The COORDINATE SYSTEM OF PROJECTION X , Y is shown for a
p p
PROJECTION ANGLE θ. For each θ, the one-dimensional PROJECTION of the marked OBJECT SLICE has the address
range shown (hatched). Within this range the CENTRE OF ROTATION is projected onto the address X (offset).
p
Figure 1 – Geometry of PROJECTIONS
3.8
COUNT LOSS
difference between measured COUNT RATE and TRUE COUNT RATE, which is caused by the finite
RESOLVING TIME of the instrument
[SOURCE: IEC 61675-1:2013, 3.8.1]
3.9
COUNT RATE
number of counts per unit of time
[SOURCE: IEC 61675-1:2013, 3.8.2]
3.10
COUNT RATE CHARACTERISTIC
COUNT RATE and TRUE COUNT RATE
function giving the relationship between observed

– 10 – IEC 61675-2:2015 © IEC 2015
[SOURCE: IEC 60788:2004, rm-34-21]
3.11
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
Note 1 to entry: The note to entry regarding the abbreviation concerns the French text only.
3.12
DETECTOR HEAD TILT
deviation of the COLLIMATOR AXIS from orthogonality with the SYSTEM AXIS
3.13
DETECTOR POSITIONING TIME
fraction of the total time spent on an acquisition which is not used in collecting data
3.14
EMISSION COMPUTED TOMOGRAPHY
ECT
imaging method for the representation of the spatial distribution of RADIONUCLIDES in selected
two-dimensional slices through the object
3.15
ENERGY WINDOW
range defining the energy signals accepted by the device for further processing
3.16
EQUIVALENT WIDTH
EW
width of that rectangle having the same area and the same height as the response function,
e.g. the POINT SPREAD FUNCTION
[SOURCE: IEC 60788:2004, rm-34-45]
3.17
FIXED COORDINATE SYSTEM
Cartesian system with axes X, Y, and Z
Note 1 to entry: Z being the SYSTEM AXIS.
Note 2 to entry: The origin of the FIXED COORDINATE SYSTEM is defined by the centre of the TOMOGRAPHIC VOLUME
(see Figure 1).
Note 3 to entry: The SYSTEM AXIS is orthogonal to all transverse slices.
3.18
IMAGE MATRIX
arrangement of MATRIX ELEMENTS in a preferentially Cartesian coordinate system
3.19
IMAGE PLANE
plane assigned to a plane in the OBJECT SLICE
Note 1 to entry: Usually the IMAGE PLANE is the mid-plane of the corresponding OBJECT SLICE.

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
INTRINSIC ENERGY SPECTRUM
measured histogram of pulse heights for the DETECTOR HEAD without COLLIMATOR
Note 1 to entry: The pulse height should be expressed as corresponding energy.
3.22
INTRINSIC NON-UNIFORMITY OF RESPONSE
NON-UNIFORMITY OF RESPONSE of the DETECTOR HEAD without COLLIMATOR
3.23
INTRINSIC SPATIAL NON-LINEARITY
SPATIAL NON-LINEARITY of the DETECTOR HEAD without COLLIMATOR
3.24
INTRINSIC SPATIAL RESOLUTION
SPATIAL RESOLUTION in air for a specified RADIONUCLIDE measured without the
COLLIMATOR
3.25
LINE SOURCE
straight RADIOACTIVE SOURCE approximating a δ-function in two dimensions and being constant
(uniform) in the third dimension
3.26
MATRIX ELEMENT
smallest unit of an IMAGE MATRIX, which is assigned in location and size to a certain volume
element of the object (VOXEL)
3.27
MULTIPLE WINDOW SPATIAL REGISTRATION
measured position of a source as a function of the ENERGY WINDOW setting
3.28
NORMALIZED VOLUME SENSITIVITY
VOLUME SENSITIVITY divided by the AXIAL FIELD OF VIEW of the tomograph or the phantom length,
whichever is the smaller
3.29
OBJECT SLICE
slice in the object
Note 1 to entry: The physical property of this slice that determines the measured information is displayed in the
tomographic image.
3.30
OFFSET
deviation of the position of the PROJECTION of the COR (X' ) from X = 0 (see Figure 1)
p p
3.31
PARALLEL HOLE COLLIMATOR
COLLIMATOR with a number of apertures, the axes of which are parallel

– 12 – IEC 61675-2:2015 © IEC 2015
3.32
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
3.33
PIXEL
MATRIX ELEMENT in a two-dimensional IMAGE MATRIX
3.34
PLANAR WHOLEBODY IMAGING EQUIPMENT
GAMMA CAMERA, with one or two DETECTOR HEAD(S), in which the image of an
extended object is formed by moving the DETECTOR HEAD(S) or the object in the axial direction
relative to each other
3.35
POINT SOURCE
RADIOACTIVE SOURCE approximating a δ-function in all three dimensions
3.36
POINT SPREAD FUNCTION
PSF
scintigraphic image of a POINT SOURCE
3.37
PROJECTION
transformation of a three-dimensional object into its two-dimensional image or of a two-
dimensional object into its one-dimensional image, by integrating the physical property which
determines the image along the direction of the PROJECTION BEAM
Note 1 to entry: This process is mathematically described by line integrals in the direction of PROJECTION and
called the Radon-transform.
3.38
PROJECTION ANGLE
angle at which the PROJECTION is measured or acquired
Note 1 to entry: See Figure 1.
3.39
PROJECTION BEAM
determines the smallest possible volume in which the physical property which determines the
image is integrated during the measurement process
Note 1 to entry: Its shape is limited by the SPATIAL RESOLUTION in all three dimensions.
Note 2 to entry: In SPECT the PROJECTION BEAM usually has the shape of a long thin diverging cone.
3.40
RADIAL RESOLUTION
TRANSVERSE RESOLUTION along a line passing through the position of the source and the
SYSTEM AXIS
[SOURCE: IEC 61675-1:2013, 3.4.1.1]
3.41
RADIOACTIVE SOURCE
quantity of radioactive material having both an ACTIVITY and a specific ACTIVITY above specific
levels
[SOURCE: IEC 60788:2004, rm-20-02]
3.42
RADIUS OF ROTATION
distance between the SYSTEM AXIS and the COLLIMATOR FRONT FACE
3.43
SCATTER FRACTION
SF
ratio between the number of scattered photons and the sum of scattered plus
unscattered photons for a given experimental set-up
3.44
SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY
SPECT
EMISSION COMPUTED TOMOGRAPHY utilizing single photon detection of gamma-ray emitting
RADIONUCLIDES
Note 1 to entry: The note to entry regarding the abbreviation concerns the French version only.
3.45
SINOGRAM
two-dimensional display of all one-dimensional PROJECTIONS of an OBJECT SLICE, as a function
of the PROJECTION ANGLE
Note 1 to entry: The PROJECTION ANGLE is displayed on the ordinate, the linear PROJECTION coordinate is displayed
on the abscissa.
[SOURCE: IEC 61675-1:2013, 3.1.2.4]
3.46
SLICE SENSITIVITY
ratio of COUNT RATE as measured on the SINOGRAM to the ACTIVITY concentration in the phantom
Note 1 to entry: In SPECT the measured counts are not numerically corrected for scatter by subtracting the
SCATTER FRACTION.
[SOURCE: IEC 61675-1:2013, 3.6]
3.47
SPATIAL NON-LINEARITY
deviations of the image of a straight LINE SOURCE from a straight line
3.48
SPATIAL RESOLUTION
ability to concentrate the count density distribution in the image of a POINT
to a point
SOURCE
[SOURCE: IEC 61675-1:2013, 3.4]
3.49
SYSTEM AXIS
axis of symmetry characterized by geometrical and physical properties of the arrangement of
the system
Note 1 to entry: The SYSTEM AXIS of a GAMMA CAMERA with rotating detectors is the axis of rotation.
[SOURCE: IEC 61675-1:2013, 3.1.2.7, modified – The note to entry has been changed]

– 14 – IEC 61675-2:2015 © IEC 2015
3.50
SYSTEM NON-UNIFORMITY OF RESPONSE
NON-UNIFORMITY OF RESPONSE of the DETECTOR HEAD with COLLIMATOR
3.51
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
RADIONUCLIDE placed perpendicular to and centred on the COLLIMATOR
containing a specified
AXIS under specified conditions
Note 1 to entry: See also Figure 2.
Dimensions in millimetres
∅ 300
∅ 170
Source
COLLIMATOR FRONT FACE (GAMMA CAMERA)
Material: polymethylmethacrylate
IEC
Figure 2 – Cylindrical phantom
3.52
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
3.53
TANGENTIAL RESOLUTION
TRANSVERSE RESOLUTION in the direction orthogonal to the direction of RADIAL RESOLUTION
[SOURCE: IEC 61675-1:2013, 3.4.1.2]
3.54
TOMOGRAPHIC VOLUME
juxtaposition of all volume elements which contribute to the measured PROJECTIONS for all
PROJECTION ANGLES
20 80
d
Note 1 to entry: For a rotating GAMMA CAMERA with a circular field of view the TOMOGRAPHIC VOLUME is a sphere
provided that the RADIUS OF ROTATION is larger than the radius of the field of view. For a rectangular field of view,
the TOMOGRAPHIC VOLUME is a cylinder.
[SOURCE: IEC 61675-1:2013, 3.1.2.8, modified – A note to entry has been added.]
3.55
TRANSVERSE POINT SPREAD FUNCTION
reconstructed two-dimensional POINT SPREAD FUNCTION in a tomographic IMAGE PLANE
Note 1 to entry: In TOMOGRAPHY, the TRANSVERSE POINT SPREAD FUNCTION can also be obtained from a LINE SOURCE
located parallel to the SYSTEM AXIS.
[SOURCE: IEC 61675-1:2013, 3.3.3]
3.56
TRANSVERSE RESOLUTION
SPATIAL RESOLUTION in a reconstructed plane perpendicular to the SYSTEM AXIS
[SOURCE: IEC 61675-1:2013, 3.4.1]
3.57
VOLUME SENSITIVITY
sum of the individual SLICE SENSITIVITIES
[SOURCE: IEC 61675-1:2013, 3.7]
3.58
VOXEL
volume element in the object which is assigned to a MATRIX ELEMENT in a two- or three-
dimensional IMAGE MATRIX
Note 1 to entry: The dimensions of the VOXEL are determined by the dimensions of the corresponding MATRIX
ELEMENT via the appropriate scale factors and by the systems SPATIAL RESOLUTION in all three dimensions.
[SOURCE: IEC 61675-1:2013, 3.2.2]
4 Test methods
4.1 General
All measurements shall be performed with the PULSE AMPLITUDE ANALYSER WINDOW set as
specified in Table 1. Additional measurements with other settings as specified by the
manufacturer can be performed. Before the measurements are performed, the tomographic
system 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. If any test
cannot be carried out exactly as specified in the standard, the reason for the deviation and the
exact conditions under which the test was performed shall be stated clearly.

– 16 – IEC 61675-2:2015 © IEC 2015
Table 1 – RADIONUCLIDES and ENERGY WINDOWS
to be used for performance measurements
RADIONUCLIDE ENERGY WINDOW
keV
99m
Tc
141 (± 7,5 %)
I 364 (± 10 %)
Ga
93, 184, 300 (± 10 %)
Co
122 (± 10 %)
NOTE Because the characteristics of a GAMMA CAMERA may change noticeably between 122 keV ( Co) and
99m
141 keV ( Tc), the former is not included as a suitable RADIONUCLIDE. However, it may be useful in some
circumstances, e.g. for quality control.

Unless otherwise specified, each DETECTOR HEAD in the system shall be characterized by a full
data set.
Unless otherwise specified, SPECT characterization shall be provided for an acquisition
covering the minimal rotation required to obtain a complete set of data (e.g. 120° for a three-
headed system). If the tomograph is specified to operate in a non-circular orbiting mode
influencing the performance parameters, test results for the non-circular orbiting mode shall be
reported in addition.
Unless otherwise specified, measurements shall be carried out at COUNT RATES not exceeding
20 000 counts per second.
4.2 Planar imaging
4.2.1 SYSTEM SENSITIVITY
4.2.1.1 General
SYSTEM 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
RADIOACTIVE SOURCE with low ACTIVITY where COUNT LOSSES are negligible.
the presence of a
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 instrument’s dead time, energy
thresholds and COLLIMATOR.
4.2.1.2 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.
4.2.1.3 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
upon accurate assays of ACTIVITY 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.
4.2.1.4 RADIONUCLIDE
The RADIONUCLIDE used for this measurement shall be appropriate for the COLLIMATOR energy
specification and chosen from Table 1.
4.2.1.5 RADIOACTIVE SOURCE distribution
The cylindrical phantom of polymethylmethacrylate as specified in Figure 2 shall be used. The
source cuvette shown in Figure 3 shall be filled with the appropriate RADIONUCLIDE 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
COLLIMATOR AXIS.
(distance d = 0) and centred on the
Dimensions in millimetres
∅170
∅150
Source
Material: polymethylmethacrylate
IEC
Figure 3 – Cuvette
NOTE Measurements of SYSTEM SENSITIVITY without scatter, using the source cuvette of Figure 3 placed at a
distance of 10 cm from the COLLIMATOR FRONT FACE, may be carried out in addition to this test.
4.2.1.6 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 C for all events
s
collected in the image.
4.2.1.7 Data processing
The ACTIVITY in the phantom shall be corrected for decay to determine the average ACTIVITY,
A , during the data acquisition time interval, T , by the following equation
ave acq
 T 
A T −T   
T
acq
cal 1/2 cal 0
 
A = exp ln2 1− exp − ln2 (1)
 
ave  
 
ln2 T T T
acq  1/ 2   1/ 2 
 
where
A is the ACTIVITY measured at time T ;
cal cal
T is the acquisition start time;
T is the RADIOACTIVE HALF-LIFE of the RADIONUCLIDE.
1/2
4.2.1.8 Data analysis
The SYSTEM SENSITIVITY S for the COLLIMATOR used shall then be found by
C
s
S = (2)
A
ave
– 18 – IEC 61675-2:2015 © IEC 2015
–1 –1
⋅ MBq .
and shall be expressed in counts ⋅ s
4.2.1.9 Report
Report the SYSTEM SENSITIVITY together with the COLLIMATOR and the RADIONUCLIDE used.
4.2.2 SPATIAL RESOLUTION
4.2.2.1 General
SPATIAL RESOLUTION determines the ability of an imaging system to reproduce the spatial
distribution of a RADIONUCLIDE in an object. 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 without the COLLIMATOR.
4.2.2.2 Purpose
The purpose of this measurement is to describe the ability of the camera to characterize small
objects.
4.2.2.3 Method
For all systems, the SPATIAL RESOLUTION shall be measured in IMAGE PLANES parallel to the
COLLIMATOR FRONT FACE by characterizing the width of the LINE SPREAD FUNCTIONS using LINE
. The width of the LINE SPREAD FUNCTION is measured by the FULL WIDTH AT HALF
SOURCES
MAXIMUM (FWHM) and the EQUIVALENT WIDTH (EW). In order to accurately measure the width of
the LINE SPREAD FUNCTION, its FWHM shall span at least ten PIXELS in the test image. Some
GAMMA CAMERAS, for example GAMMA CAMERAS with detectors composed of multiple crystals,
may not be able to achieve ten PIXELS in the FWHM in the test image. In this case the matrix
used for the test shall be specified and proper interpolation shall be used and stated.
4.2.2.4 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
99m
INTRINSIC SPATIAL RESOLUTION the RADIONUCLIDE shall be Tc.
4.2.2.5 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 length at least equal to the longer detector axis.
For the measurement of INTRINSIC SPATIAL RESOLUTION, a multiple slit transmission phantom
shall be used as shown in Figure 4.

Dimensions in millimetres
D = Appropriate size and shape for different
camera fields of view and larger than
DETECTOR FIELD OF VIEW
30 30 30 30 30 30
D
Aluminium alloy 3 mm
Lead (4 % antimony) 3 mm
Aluminium alloy 0,5 mm
IEC
Towards the detector
NOTE 1 Slit width 1,0 mm ± 0,05 mm.
NOTE 2 Slit straightness ± 0,05 mm over any 30 mm length.
NOTE 3 Slit centre separation 30,0 mm ± 0,05 mm.
Figure 4 – Slit phantom
This phantom covers the entire DETECTOR FIELD OF VIEW and shall be placed at the centre of the
detector face (COLLIMATOR removed). A POINT SOU
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