1、 NEMA NU 2-2012 Performance Measurements of Positron Emission Tomographs NEMA NU 2-2012 Performance Measurements of Positron Emission Tomographs Published by: National Electrical Manufacturers Association 1300 N. 17th Street Rosslyn, VA 22209 www.nema.org www.medicalimaging.org/ Copyright 2013 by th
2、e 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, and the International and Pan American Copyright Conventions. NU 2-2012 P
3、age ii Copyright 2013 by 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 time it was developed. Consensus does not neces
4、sarily mean that there is unanimous agreement among every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consensu
5、s standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not writ
6、e the document and it does not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal injury, property, or other damages of any nature w
7、hatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, express or implied, as to the accuracy or completeness of any information
8、published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or sellers products or services by virtue of this standard or guide.
9、In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her
10、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 from other sources, which the user may wish to
11、 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 installations for safety or health purposes. Any ce
12、rtification 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. NU 2-2012 Page iii Copyright 2013 by National Electrical Manufacturers Association
13、 FOREWORD Reason for Changes The regulations regarding the maintenance of standards by NEMA requires that the standards be reviewed and, if necessary, updated every five years. This standards publication was developed by the Coincidence Imaging Task Force chartered by the Nuclear Standards and Regul
14、atory Committee. Committee approval of the standard does not necessarily imply that all committee members voted for its approval or participated in its development. At the time it was approved, the task force was composed of the following members: Siemens Healthcare Knoxville, TN GE Healthcare Princ
15、eton, NJ Bracco Diagnostics Princeton, NJ Lantheus Medical Imaging North Billerica, MA Bayer Healthcare Pharmaceuticals Berlin, Germany Naviscan, Inc. San Diego, CA Philips Healthcare Highland Heights, OH GE Healthcare Waukesha, WI Toshiba Medical Research Institute USA, Inc. Vernon Hills, IL In the
16、 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 by contacting the: Vice President Medical Imaging but, the value
17、 of 1.830 hours (or 109.8 minutes or 6588 seconds) used in previous versions of this standard may continue to be used with negligible impact on measured results. rate (Rxxx): A coincidence event rate measured in events per second, defined as the coincidence counts divided by the time interval Tacq:
18、a) RROI : rate in a planar region of interest b) RTOT : total event rate c) RFit : fit event rate d) Rt : true event rate e) Rs : scatter event rate f) Rr : random event rate g) Rt,peak : peak true event rate h) RNEC : noise equivalent count rate i) RNEC,peak : peak noise equivalent count rate j) RC
19、ORR : decay-corrected count rate time (Txxx): A time measured in seconds: 1 NIST standard reference database 12. Tilley, D. R., H. R. Weller, et al. (1995). “Energy levels of light nuclei A = 18-19.“ Nuclear Physics A 595(1): 1-170. NU 2-2012 Page 3 Copyright 2013 by National Electrical Manufacturer
20、s Association a) Tacq : duration of an acquisition b) Tj : starting time of acquisition j c) Tcal : time of well counter measurement volume (V): A physical volume measured in milliliters. 1.3 REFERENCED PUBLICATIONS Daube-Witherspoon ME, Karp JS, Casey ME, DiFilippo FP, Hines H, Muehllehner G, Simci
21、c V, Stearns CW, Adam L-E, Kohlmyer S and Sossi V. “PET Performance Measurements Using the NEMA NU 2-2001 Standard.” Journal of Nuclear Medicine 43, no. 10 (2002): 1398-1409. Daube-Witherspoon ME and Muehllehner G. “Treatment of axial data in three-dimensional PET.” Journal of Nuclear Medicine 28, n
22、o. 11 (1987): 1717-1724. Strother SC, Casey ME and Hoffman EJ. “Measuring PET Scanner Sensitivity: Relating Countrates to Image Signal-to-Noise Ratios using Noise Equivalents Counts.”IEEE Transactions on Nuclear Science 37, no. 2 (1990): 783-788. Tilley, D. R., H. R. Weller, et al. (1995). “Energy l
23、evels of light nuclei A = 18-19.“ Nuclear Physics A 595(1): 1-170. Watson CC, Casey ME, Eriksson L, Mulnix T, Adams D and Bendriem B. “NEMA NU 2 Performance Tests for Scanners with Intrinsic Radioactivity.” Journal of Nuclear Medicine 45, no. 5 (2004): 822-826. IEC 61675-1 Radionuclide Imaging Devic
24、esCharacteristics and Test Conditions. Part 1: Positron Emission Tomographs, 1998. NIST Standard Reference Database 120: Radionuclide Half-life Measurements. Online www.nist.gov/pml/data/halflife.cfm. Accessed 23 February 2012. NU 2-2012 Page 4 Copyright 2013 by National Electrical Manufacturers Ass
25、ociation NU 2-2012 Page 5 Copyright 2013 by National Electrical Manufacturers Association Section 2 GENERAL 2.1 PURPOSE The intent of this standards publication is to specify procedures for evaluating performance of positron emission tomographs. The resulting standardized measurements can be cited b
26、y manufacturers to specify the guaranteed performance levels of their tomographs. As these measures become available throughout the industry, potential customers may compare the performance of tomographs from various manufacturers. The standard measurement procedures can be used by customers for acc
27、eptance-testing of tomographs before and after installation of the equipment. In defining this standard, language referring to levels of standard such as class standard versus performance standard or typical values versus meet or exceed has been avoided. Determining the frequency of sampling of syst
28、ems for each test is left to the manufacturer. Because both the difficulty of performing the various measurements and the accuracy of each tests results vary, the decision of quoting a result as a typical or met/exceeded value is also left to the manufacturer. 2.2 PURVIEW It is assumed that every sy
29、stem to be tested under this standard is able to create sinograms and transverse slice images, define and manipulate two-dimensional regions of interest with circular and rectangular boundaries, and extract such parameters as coincidence event counts detected within specified intervals of time. The
30、system is also assumed to have transverse fields of view suitable for human subjects. For all of the procedures except for the image quality test, the scanner must have an accessible diameter of at least 260 millimeters. The test phantom for all of the procedures except for the image quality test, i
31、s 70.0 cm in length and is suitable for performing measurements in all slices of tomographs with an axial field of view of less than 65 cm. The image quality test, which requires a different test phantom can only be performed on a scanner with an accessible diameter of at least 350 millimeters. Whil
32、e this precludes the performance of the image quality test on some brain-only scanners, it is important to note that the image quality test is designed to emulate whole-body imaging performance, and therefore is not appropriate for a brain-only tomograph. The intent of this standard is to provide a
33、set of measurements that permit the comparison of positron emission tomograph performance. Though it may be useful to have tests tailored to specific tasks or patient geometries, such additional tests do not add substantial value in the comparison of systems. The range of tests in this standard is n
34、ot intended to restrict or discourage alternative tests. A specific example would be the NU 2-1994 Scatter Fraction and Count Rate Test. The source geometry in this test is a better approximation to the human brain than the 70 cm source length in the current standard. However, for the purposes of ge
35、neral comparison, a system that performs better on the method in this standard will also be better on the geometry-specific test. A comprehensive comparison in different geometries is a valid topic for the research literature, but is not suitable for a test standard that may be applied to a producti
36、on environment. The measurements described in this standards publication have been designed with a primary focus on whole body imaging for oncologic applications. As such, these measurements may not accurately represent the performance of a positron emission tomograph in brain imaging applications.
37、These specifications represent a subset of measurements that define the performance of positron emission tomographs. Furthermore, the scope of this standard is limited to measurement of the performance of the positron emission tomograph component of multi-modality imaging systems. NU 2-2012 Page 6 C
38、opyright 2013 by National Electrical Manufacturers Association 2.3 UNITS OF MEASURE Systme International dUnits (SI) units shall be used in all reports of positron emission tomograph performance measurements. Customary units such as millicuries may be optionally reported as auxiliary values in paren
39、thetical statements with the standard specifications for individual performance reports. 2.4 CONSISTENCY All measurements must be performed without altering any of the instruments parameters that are mutually exclusive, unless otherwise directed for a particular measurement. These include but are no
40、t limited to the following parameters: energy discrimination windows (including the utilization of multiple energy windows in photopeak-Compton imaging modes), coincidence timing window(s), pulse integration time, reconstruction algorithm with associated parameters, pixel size, slice thickness, axia
41、l acceptance angle, and axial averaging or smoothing. If multiple operating modes are supported by the instrument, the operating mode used for each measurement shall be clearly specified. For instruments with movable detector elements the detector positions and trajectories shall be those recommende
42、d by the manufacturer and shall remain the same for all acquisitions. These motions include but are not limited to the detector separation distance, orbit trajectory around the patient to produce a full tomographic data set, and motions to increase sampling such as detector wobble or table displacem
43、ents. The reconstruction algorithm, with its associated parameters, matrix, and pixel size shall be that recommended by the manufacturer and shall remain fixed for all of the NEMA measurements of tomograph performance unless otherwise directed for a particular measurement. Most systems organize the
44、raw measurements into parallel projection matrices corresponding to transverse slices before performing a 2-D tomographic image reconstruction. This can lead to errors in positioning depending on the axial acceptance angle, particularly in the axial direction, as the radial distance from the center
45、increases. Some systems can change the axial acceptance angle by adjusting the septa shielding, while others specify the angle in software. For systems that acquire and reconstruct 3-D measurements, it is assumed that the volume imaged can be oriented into transaxial slices for data analysis. The ac
46、ceptance angle shall be that recommended by the manufacturer and shall remain fixed for all of the NEMA measurements of tomograph performance. Some measurements explicitly require volumetric data to be re-sorted into transverse sinograms using the single-slice rebinning method, as described in “Trea
47、tment of axial data in three-dimensional PET” for all other measurements, the manufacturers recommended treatment of volumetric data shall be used. The energy window or windows used for these measurements must be specified. If multiple windows are used in a photopeak-Compton imaging mode, that mode
48、shall also be specified. These window settings shall be those recommended by the manufacturer and shall remain fixed during all of the NEMA measurements of a tomographs performance. Each measurement procedure specifies the method of source support, whether the source is to be suspended in the field
49、of view or supported by some means. For those measurements in which the source is to be supported, the source shall be placed on the patient table. Unless specified otherwise in the description of a particular measurement, phantom positioning instructions carry a nominal tolerance of 5 mm in both the transaxial and the axial directions. 2.5 EQUIVALENCY 18F is specified for all of the tests. For some measurements, substitution of another radionuclide, such as 68Ga can lead to significantly different results due to such factors as positron range and activity
