1、NEMA Standards Publication National Electrical Manufacturers Association NEMA NU 2-2018 Performance Measurements of Positron Emission Tomographs (PET)NEMA Standards Publication NU 2-2018 Performance Measurements of Positron Emission Tomographs (PET) Published by: National Electrical Manufacturers As
2、sociation 1300 N. 17 thStreet, Suite 900 Rosslyn, VA 22209 www.nema.org 2018 National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works
3、, and the International and Pan American Copyright Convention. 2018 National Electrical Manufacturers Association. NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the tim
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10、ing this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available fr
11、om other sources, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or install
12、ations for safety or health purposes. Any certification or other statement of compliance with any health or safetyrelated information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. NEMA NU 2-2018 Page i 2018 National El
13、ectrical Manufacturers Association. CONTENTS Foreword iv Definitions, Symbols, and Referenced Publications . 1 Section 1 1.1 Definitions 1 1.2 Standard Symbols . 1 1.3 Referenced Publications 3 General . 4 Section 2 2.1 Purpose . 4 2.2 Purview 4 2.3 Units of Measure . 5 2.4 Consistency . 5 2.5 Equiv
14、alency . 5 Spatial Resolution . 7 Section 3 3.1 General 7 3.2 Purpose . 7 3.3 Method . 7 3.3.1 Radionuclide 7 3.3.2 Source Distribution 7 3.3.3 Data Collection 8 3.3.4 Data Processing 8 3.4 Analysis . 8 3.5 Report 9 Scatter Fraction, Count Losses, and Randoms . 10 Section 4 4.1 General 10 4.2 Purpos
15、e . 10 4.3 Method . 10 4.3.1 Symbols . 11 4.3.2 Radionuclide 11 4.3.3 Source Distribution 11 4.3.4 Data Collection 12 4.3.5 Data Processing 12 4.4 Analysis . 13 4.4.1 Analysis with Randoms Estimate 14 4.4.2 Alternative Analysis with No Randoms Estimate 15 4.5 Report 16 4.5.1 Count Rate Plot . 16 4.5
16、.2 Peak Count Values 16 4.5.3 System Scatter Fraction 16 4.5.4 Table and Phantom Positioning, and Projection Alignment 16 Sensitivity . 17 Section 5 5.1 General 17 5.2 Purpose . 17 5.3 Method . 17 5.3.1 Symbols . 17 5.3.2 Radionuclide 17 5.3.3 Source Distribution 18 5.3.4 Data Collection 18 5.4 Calc
17、ulations and Analysis 18 5.4.1 System Sensitivity . 18 5.4.2 Axial Sensitivity Profile 19 5.5 Report 19 NEMA NU 2-2018 Page ii 2018 National Electrical Manufacturers Association. Accuracy: Corrections for Count Losses and Randoms 21 Section 6 6.1 General 21 6.2 Purpose . 21 6.3 Method . 21 6.3.1 Sym
18、bols . 21 6.3.2 Radionuclide 21 6.3.3 Source Distribution 21 6.3.4 Data Collection 21 6.3.5 Data Processing 21 6.4 Analysis . 21 6.5 Report 22 Image Quality, Accuracy of Corrections . 23 Section 7 7.1 General 23 7.2 Purpose . 23 7.3 Method . 23 7.3.1 Symbols . 23 7.3.2 Radionuclide 23 7.3.3 Source D
19、istribution 24 7.3.4 Data Collection 24 7.3.5 Data Processing 25 7.4 Analysis . 25 7.4.1 Image Quality 25 7.4.2 Accuracy of Corrections 26 7.5 Report 26 Time-of-Flight Resolution . 30 Section 8 8.1 General 30 8.2 Purpose . 30 8.3 Method . 30 8.3.1 Symbols . 30 8.3.2 Radionuclide 31 8.3.3 Source Dist
20、ribution 31 8.3.4 Data Collection 31 8.3.5 Data Processing 31 8.4 Analysis . 32 8.4.1 2-D Histogram formation . 32 8.4.2 Scatter and Random Removal 33 8.4.3 FWHM Analysis . 33 8.5 Report 33 PET-CT Coregistration Accuracy . 35 Section 9 9.1 General 35 9.2 Purpose . 35 9.3 Method . 35 9.3.1 PET-CT Fid
21、ucial Marker 35 9.3.2 Fiducial Marker and Mass Distribution 35 9.3.3 Data Collection 36 9.3.4 Data Processing 37 9.4 Analysis . 37 9.4.1 PET and CT Image Fusion 37 9.4.2 Processing of Data 37 9.4.3 Location of Maximum Voxel Value in the PET and CT Data . 37 9.4.4 Dimensions of the Volume Used in the
22、 Calculation of the Centroid . 38 9.4.5 PET and CT Centroids 39 9.4.6 Verification of Fiducial Marker Dimension and Pixel Size . 39 NEMA NU 2-2018 Page iii 2018 National Electrical Manufacturers Association. 9.4.7 Coregistration Error . 40 9.5 Report 41 NEMA NU 2-2018 Page iv 2018 National Electrica
23、l Manufacturers Association. Foreword Reason for Changes NEMA requires that its standards be reviewed and, if necessary, updated every five years. This standards publication was developed by the NU 2 Task Force chartered by the Molecular Imaging Section of MITA. Committee approval of the standard do
24、es not necessarily imply that all committee members voted for its approval or participated in its development. The task force was composed of the following members: Yanic BercierSiemens Healthineers, Knoxville, TN Michael A. MillerPhilips, Highland Heights, OH Charles W. StearnsGE Healthcare, Waukes
25、ha, WI Jeffrey KolthammerCanon Medical, Vernon Hills, IL In the preparation of this standards publication, input of users and other interested parties has been sought and evaluated. Inquiries, comments, and proposed or recommended revisions should be submitted to the concerned NEMA product section b
26、y contacting the: Senior Technical Director, Operations National Electrical Manufacturers Association 1300 North 17 thStreet, Suite 900 Rosslyn, Virginia 22209 Changes to Tests The changes made by the Task Force from the 2012 version of this standard include the addition of two new sections: a. Sect
27、ion 8, to assess the coincidence timing resolution of tome-of-flight PET systems, and b. Section 9, to assess the co-registration accuracy of hybrid PET/CT systems. Other changes to the current version are relatively minor, mostly designed to make the tests easier to conduct, more reproducible, more
28、 clearly defined, or better harmonized with other performance tests. These are the most substantial changes to the tests (note that this is not intended to be an exhaustive list): a. In Section 3, the spatial resolution test allows 22 Na as well as 18 F. b. In Section 3, the spatial resolution test
29、point source is specified in terms of point source dimensions as opposed to capillary tube dimensions. The capillary tube is specified as an option. c. In Section 4 (and in Section 6 and Section 8, which use the same acquired data), the test phantom is to be positioned so that the trough of the tabl
30、e is positioned 15 1 cm below the center of the transverse field of view (FOV). d. In Section 6, the analysis is to be conducted over the central 80% of the PET axial FOV. e. In Section 7, the 28 mm and 37 mm diameter cold spheres are replaced with 28 mm and 37 mm diameter hot spheres. All six spher
31、es are to be hot. f. In Section 7, there is no option for a hot sphere-to-background fill ratio of 8:1. g. In Section 7, the lung residual error analysis excludes slices that are within 30 mm of the axial edge of the lung insert; the previous value was 10 mm. h. In Section 7, the description of phan
32、tom positioning is clarified. If the patient table cannot center the body phantom lung insert, adjust the patient table height to center the phantom as closely as possible. The phantom shall not be elevated above the patient table surface in order to center the phantom lung insert. NEMA NU 2-2018 Pa
33、ge v 2018 National Electrical Manufacturers Association. Scope The philosophy and rationale of the standards measurements and illustrative examples of the analysis and results are presented in Journal of Nuclear Medicine, vol. 43, no. 10, 2002. Daube-Witherspoon ME, Karp JS, Casey ME, DiFilippo FP,
34、Hines H, Muehllehner G, Simcic V, Stearns CW, Adam L-E, Kohlmyer S and Sossi V. “PET Performance Measurements Using the NEMA NU 2-2001 Standard.” pp. 1398-1409. With the exceptions of Section 8 for time-of-flight systems and Section 9 for hybrid PET/CT systems, the Task Force has attempted to specif
35、y methods that can be performed on all positron emission tomographs. These include single and multiple slice, discrete and continuous detector, time-of-flight instruments, multi-planar and volume reconstruction models, and dedicated positron emission tomographs as well as other coincidence-capable i
36、maging systems. Wherever possible, future developments that could be readily anticipated were taken into account. While many PET tomographs are constructed as hybrid imaging systems such as PET/CT and PET/MR systems, the standards committee has not specified special methods to assess hybrid imaging
37、performance with the exception of the PET/CT registration test described in Section 9. It is expected that the PET component of a hybrid imaging system can be assessed using the methods described in this standard, and other portions of the system can be assessed using other standards appropriate to
38、that technology. The method for assessing the co-registration accuracy of hybrid PET/CT systems has the potential to be adapted to PET/MR systems. In the event a portion of any of the PET test methods described here cannot be executed in a hybrid imaging system, workaround methods may be used, but t
39、hose methods must be described in the test report. NEMA NU 2-2018 Page vi 2018 National Electrical Manufacturers Association. NEMA NU 2-2018 Page 1 2018 National Electrical Manufacturers Association. Section 1 Definitions, Symbols, and Referenced Publications 1.1 Definitions axial field of view (FOV
40、): The maximum length parallel to the long axis of a positron emission tomograph along which the instrument generates transaxial tomographic images. full-width at half-maximum (FWHM): A measure of spread of a distribution given by the difference between points where the value reaches half the maximu
41、m value. line of response (LOR): The line in 3-D space formed by a coincidence events two-end detected points. list-mode: A correlated projection data file format where each coincidence event is listed sequentially, parameter by parameter. For the purposes of this standard, the list mode data is ass
42、umed to include information describing the spatial position of the LOR, and, if the data is acquired in a time-of-flight (TOF) mode, the TOF information about each recorded coincidence event. prompt counts: Coincidence events acquired in the standard coincidence window of a positron emission tomogra
43、ph. Prompt counts include true, scattered, and random coincidence events. sinogram: A two-dimensional representation of projection space data, where one dimension refers to radial distance from the center, and the second dimension refers to projection angle. time-of-flight (TOF): Arrival time differ
44、ence of two photons in a coincidence event, from which the annihilation point along the LOR can be estimated. transverse field of view (FOV): The maximum diameter circular region perpendicular to the long axis of a positron emission tomograph within which objects might be imaged. test phantom: Compo
45、nents for each measurement are defined in the description of that measurement. 1.2 Standard Symbols Symbolic expressions for certain quantities are used throughout this standards publication. Symbols that use any one of the standard subscripts to specify further a basic quantity are identified by th
46、e subscript string “ xxx .” Symbols which represent quantities that are indexed over a series of acquisitions and/or each slice in an image or data set may have that indexing identified by further subscript strings such as “, j ” or,“ j,j ”as defined in the related text. All quantities expressed as
47、a function of some independent variable shall be symbolically represented as Q(x), where x is a lower-case letter representing the variable as defined in the related text. counts ( ): The number of coincidence events: a. events in a planar region of interest b. total number of events c. + random plu
48、s scatter event count d. event count at left edge of projection area of interest e. event count at right edge of projection area of interest f. counts in a hot region of interest NEMA NU 2-2018 Page 2 2018 National Electrical Manufacturers Association. g. C B counts in a background region of interes
49、t radioactivity (A xxx ): A nuclear decay rate in units of megabecquerels (MBq), i.e., in units of 1 million disintegrations per second, and optionally expressed in units of millicuries (mCi), i.e., in units of 37 million disintegrations per second: a. c al,me as radioactivity at time cal , as measured in the dose calibrator b. c al line source radioactivity corrected for source length c. a ve average radioactivity during an acqu
