1、 NEMA UD 3 STANDARD FOR REAL-TIME DISPLAY OF THERMAL AND MECHANICAL ACOUSTIC OUTPUT INDICES ON DIAGNOSTIC ULTRASOUND EQUIPMENT, REVISION 2 NEMA Standards Publication UD 3-2004 (R2009) Standard for Real-Time Display of Thermal and Mechanical Acoustic Output Indices on Diagnostic Ultrasound Equipment,
2、 Revision 2 Contains Errata Reaffirmed August 4, 2009 Published by: National Electrical Manufacturers Association 1300 North 17th Street, Suite 1752 Rosslyn, Virginia 22209-3801 www.nema.org American Institute of Ultrasound in Medicine 14750 Sweitzer Lane, Suite 100 Laurel, Maryland 20707-5906 www.a
3、ium.org Copyright 2004 by the 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 Copyri
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5、ery 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 consensus standards development process. This process brings t
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10、MA 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 own independent judgment or, as appropriate, seek th
11、e 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 consult for additional views or information not cov
12、ered 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 certification or other statement of compliance with an
13、y 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. ERRATA NEMA UD 3-2004 Standard for Real-Time Display of Thermal and Mechanical Acoustic Output Indices on Diagnostic Ultrasound Equipm
14、ent, Revision 2, has the following errata. Page 11, Subclause 4.1.3.1, second paragraph Replace “,” with “.” after “for the real-time (B-mode) mode”. Page 19, Equation 6.2.4.2-1. Replace with: () ( )()( ) =2zjcf03.0mjmj3.cmmJ10z,v,jPIIofzonmaxv,jPIImaximumspatial Page 19, Equation 6.2.4.2-2. Replace
15、 with: ()()()=23.mjPIIzjcf03.03.mjPIImjmj3.cmmJ10z,v,jPIIv,jPIImaximumspatial Page 21, Equation 6.2.5.2-2. Replace with: ()()()()=23.BmjPIIzjcf03.023.BmjPIImjmj3.BcmmJ10z,v,jPIIv,jPIImaximumspatial Page 21, Equation 6.2.5.4-2. Replace with: () ()()()=23.BmjPIIzjcf03.023.BmjPIIaTAa3.BSPTAcmmW10z,v,jI
16、v,jI Page 22, Equation 6.2.5.5-2. Replace with: ()()()()( )=4.4z,v,jW;1050z,v,jIv,jWminv,jTIB3.BmjPIIa3.3BmjPIIzjcf03.03.BmjPIIaTAaaPage 22, Equation 6.2.6.2-1 Replace with: Aaprt(j) 1 cm2Page 23, Subclause 6.2.6.20 Replace “Aaprt(j)=1cm2” with “Aaprt(j) Copyright 2004 by the National Electrical Man
17、ufacturers Association. UD 3-2004 (R2009) Page 1 Section 1 REFERENCED PUBLICATIONS 1.1 GENERAL This standards publication is classified as an AIUM standard and as a NEMA standard, unless otherwise indicated, and establishes definitions and aspects of indication/display and operator control features
18、relevant to acoustic output levels of diagnostic ultrasound equipment. 1.2 REFERENCED PUBLICATIONS In this publication, reference is made to the standards listed below. Copies are available from the indicated sources. Acoustic Output Measurement Standard for Diagnostic Ultrasound Equipment (AOMS-199
19、8) American Institute of Ultrasound in Medicine (AIUM) 14750 Sweitzer Lane, Suite 100 Laurel, MD 20707-5906 (301) 498-4100 FAX: (301) 498-4450 (NEMA UD 2-1998) National Electrical Manufacturers Association (NEMA) 1300 North 17th Street, Suite 1752 Rosslyn, VA 22209-3801 Standards are available throu
20、gh Global Engineering Documents 1-800-854-7179 FAX: 303-397-2740 Copyright 2004 by the National Electrical Manufacturers Association. UD 3-2004 (R2009) Page 2 Section 2 DEFINITIONS AND FORMULAE For the purposes of this standard, the following terms are defined in specific language which either repla
21、ces or supplements, as appropriate, the corresponding definitions in the AIUM/NEMA Acoustic Output Measurement Standard for Diagnostic Ultrasound Equipment, referenced as NEMA Standard UD 2-1998 or as AIUM Standard AOMS-1998. Unless explicitly defined in this section, all other terms retain the defi
22、nitions as described in the corresponding Section 1 of AIUM Standard AOMS-1998 or NEMA Standard UD 2-1998. For terms not covered in this document, consult the 1997 AIUM Recommended Ultrasound Terminology. Where used in this standard, the terms defined below and the terms defined in Section 1 of the
23、AIUM Standard AOMS-1998 and NEMA Standard UD 2-1998 are in bold letters. 2.1 GENERAL DEFINITIONS acoustic output: The ultrasound emitted from the transducer assembly into the body. In normal usage, this ultrasound is directed into the body of the patient being examined. For most cases, this acoustic
24、 output is estimated by measurements in a water medium, with a derating factor included. active aperture: The aperture defined by the entrance beam dimensions for unscanned cases or entrance dimensions of the scan for scanned cases defined in Section 1 of NEMA Standard UD 2-1998 or AIUM Standard AOM
25、S-1998. In cases with nonuniform excitation of the transducer elements in contact with the skin, the area (in cm2) of the active aperture at the beam entrance shall be taken as the maximum dimensions at which the rms excitation voltage, varmsper unit transducer area exceeds 12 dB, relative to the sp
26、atial maximum varmsper unit transducer area. This definition for nonuniform excitation is intended to cover phased arrays, linear, and curved arrays in both scanned and unscanned modes. This definition is also applicable to annular array-based mechanical probes in both scanned and unscanned modes. b
27、eam axis: A straight line joining the points of maximum pulse intensity integral (PII), measured at several different distances in the far field. This line, calculated according to regression rules, is to be extended back to the transducer assembly surface. bone thermal index (TIB): The thermal inde
28、x for applications, such as fetal (second and third trimester) or neonatal cephalic (through the fontanelle), in which the ultrasound beam passes through soft tissue and a focal region is in the immediate vicinity of bone. (See Tables 21, 22, 23, and 24 for thermal index categories and formulae.) ce
29、nter frequency (fc): (f1+ f2)/2, where f1and f2are frequencies defined in bandwidth. center frequency for jthtransmit pattern (fc(j) in MHz): The center frequency, as defined in the NEMA Standard UD 2-1998 or in AIUM Standard AOMS-1998, for the jthtransmit pattern, except that the subject acoustic w
30、aveform is measured at the point of free-field spatial-maximum pulse intensity integral (PII), and the transmit pattern is operated at its maximum drive voltage amplitude. cranial bone thermal index (TIC): The thermal index for applications, such as pediatric and adult cranial applications, in which
31、 the ultrasound beam passes through bone near the beam entrance into the body. (See Tables 21, 22, 23, and 24 for thermal index categories and formulae.) combined mode (combined operating mode): Any combination of two or more of the discrete operating modes operating simultaneously. Copyright 2004 b
32、y the National Electrical Manufacturers Association. UD 3-2004 (R2009) Page 3 default setting: A system control state which is pre-set by the manufacturer or operator. derating factor: A multiplicative factor applied to acoustic output parameters intended to account for ultrasonic attenuation of tis
33、sue between the source and a particular location in the tissue. In the calculation of all mechanical and thermal indices in this standard, the average ultrasonic attenuation is assumed to be 0.3 dB/cmMHz along the beam axis in the body. discrete operating mode: One of the following system operations
34、: A-Mode, M-Mode, static B-Mode, real-time B-Mode, CW Doppler, pulsed Doppler, static flow mapping, real-time flow mapping, or any other single display format for presenting clinical information. display accuracy: As used in this standard, is a manufacturers specification of how closely the displaye
35、d index values correspond to actual index values, i.e., values computed using formulae and values of acoustic output quantities measured per methodology as specified in this standard. drive voltage amplitude (va): The temporal-peak amplitude of an electrical drive waveform applied to a transducer or
36、 array of transducer elements. entrance beam dimensions: The dimensions of the 12dB beam width where the beam enters the patient. For contact transducers, these dimensions can be taken as the dimensions of the radiating element, if so stated. entrance dimensions of the scan: For autoscan systems, ar
37、e the dimensions of the area of the surface through which the scanned ultrasound beams enter the patient, consisting of all points located within the 12 dB beam width of any beam passing through that surface during the scan. equipment: The combination of a specific ultrasound console and a specific
38、transducer assembly. full software control of acoustic output: The means by which the equipment establishes values of the acoustic output quantities independent of direct operator control. indication/display: The means by which the operator is informed of equipment operation or characteristics. Thes
39、e means may include either dynamic displays or on-equipment labeling. indication/display increment: The discrete range step between adjacent displayed levels. maximum drive voltage amplitude (vmj): The largest drive voltage amplitude that is applied to any element in the jthtransmit pattern in any o
40、perating condition allowed in clinical use by a specific system including both hardware and software configurations. Copyright 2004 by the National Electrical Manufacturers Association. UD 3-2004 (R2009) Page 4 mechanical index (MI) formula: The spatial-peak value of the peak rarefactional pressure,
41、 derated by 0.3 dB/cmMHz at each point along the beam axis, divided by the square root of the center frequency, that is: ( )csp3.rfzpMI = (2.11) where: pr.3(zsp) is the peak rarefactional pressure (in MPa) derated by 0.3 dB/cmMHz to the point on the beam axis, zsp, pulse intensity integral (PII.3) i
42、s maximum, and fcis the center frequency (in MHz). To make the mechanical index unitless, the righthand side of equation 2.11 is multiplied by (1 MHz)0.5/(1 MPa). For combined modes, the mechanical index for the discrete operating mode with the largest derated peak rarefactional pressure is reported
43、. operator: The person who performs the ultrasound examination. NOTEThe physician is always responsible for the ultrasound examination, but is not the only person who performs examinations. operator control feature: The means by which the operator may modify the operation of the equipment. peak rare
44、factional pressure (prin MPa): The temporal peak rarefactional pressure amplitude at a specified point. prudent use statement: An affirmation of the principle advising the use of acoustic output levels and exposure times, as low as reasonably achievable (ALARA principle), while acquiring necessary c
45、linical information. pulse intensity integral (PII): The time integral of instantaneous intensity, for any specific point and pulse, integrated over the time in which the envelope of acoustic pressure or hydrophone signal for the specific pulse is non-zero. It is equal to the energy fluence per puls
46、e. For a transducer assembly operating in a nonautoscanning mode, it is equal to the product of temporal average intensity and pulse repetition period. scanned mode (auto-scanning): The electronic or mechanical steering of successive ultrasonic pulses or series of pulses, through at least two dimens
47、ions. soft tissue thermal index (TIS): The thermal index related to soft tissues. (See Tables 21, 22, 23, and 24 for thermal index categories and formulae.) system control feature: A means by which the equipment automatically modifies its operation. thermal index (TI): A quantity related to calculat
48、ed or estimated temp rise under certain defined assumptions. The thermal index is the ratio of total acoustic power to the acoustic power required to raise tissue temp by 1C under defined assumptions. In the calculation of all thermal indices in this standard, the average ultrasonic attenuation is a
49、ssumed to be 0.3 dB/cmMHz along the beam axis in the body (see Tables 21, 22, 23, and 24 for thermal index categories and formulae). Copyright 2004 by the National Electrical Manufacturers Association. UD 3-2004 (R2009) Page 5 transducer assembly: The transducer(s), the transducer housing (probe), any associated electronic circuitry and any liquids contained in the housing, and the integral cable which connects the transducer probe to an ultrasound console. transmit pattern (j): The combination, denoted by t
