1、DRAFT FOR DEVELOPMENTDD IEC/TS 62306:2006Ultrasonics Field characterisation Test objects for determining temperature elevation in diagnostic ultrasound fieldsICS 11.040.55g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g
2、40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58DD IEC/TS 62306:2006This Draft for Development was published under the authority of the Standards Policy and Strategy Committee on 29 February 2008 BSI 2008ISBN 978 0 580 55052 2National forewordThis Draft for Development is the
3、UK implementation of IEC/TS 62306:2006. This publication is not to be regarded as a British Standard.It is being issued in the Draft for Development series of publications and is of a provisional nature. It should be applied on this provisional basis, so that information and experience of its practi
4、cal application can be obtained.Comments arising from the use of this Draft for Development are requested so that UK experience can be reported to the international organization responsible for its conversion to an international standard. A review of this publication will be initiated not later than
5、 three years after its publication by the international organization so that a decision can be taken on its status. Notification of the start of the review period will be made in an announcement in the appropriate issue of Update Standards.According to the replies received by the end of the review p
6、eriod, the responsible BSI Committee will decide whether to support the conversion into an international Standard, to extend the life of the Technical Specification or to withdraw it. Comments should be sent to the Secretary of the responsible BSI Technical Committee at British Standards House, 389
7、Chiswick High Road, London W4 4AL.The UK participation in its preparation was entrusted to Technical Committee EPL/87, Ultrasonics.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisio
8、ns of a contract. Users are responsible for its correct application.Amendments/corrigenda issued since publicationDate CommentsIECTECHNICAL SPECIFICATION TS 62306First edition2006-03Ultrasonics Field characterisation Test objects for determining temperature elevation in diagnostic ultrasound fields
9、Reference number IEC/TS 62306:2006 DD IEC/TS 62306:2006CONTENTS 1 2 3 4 5 5.1 6 6.1 6.2 7 7.1 7.2 Annex E (informative) Derivation of perfused temperature history from unperfused Figure 3 Schematic representation of a thermal test assembly at two different distances and of the transmission loss, L,
10、required by the selected physical tissue Table A.1 Ratio of unperfused temperature to perfused temperature for a type A soft tissue target region of perfusion time constant 32 s to 3 160 s after 180 s insonation by Table A.2 Ratio of unperfused temperature to perfused temperature for a type C fetal
11、bone target region of perfusion time constant 32 s to 3 160 s after 180 s insonation by Table B.2 Specification of target tissue materials for use in thermal sensor test 2 DD IEC/TS 62306:2006INTRODUCTION.3 Scope.4 Normative references4 Terms and definitions .4 List of symbols8 Thermal test assembly
12、8 Specification of a thermal test assembly 9 Specification of a thermal sensor 11 Thermal sensor .11 Sensing electronics .12 Use of a thermal test assembly .12 General .12 Perfusion.13 Annex A (informative) Rationale .16 Annex B (informative) Clinical and physical tissue models 19 Annex C (informati
13、ve) Construction of an example thermal test assembly.25 Annex D (informative) Procedures for validating performance .28 temperature history .31 Annex F (informative) Guidance on measurement procedures 32 Annex G (informative) Instructions for making example soft tissue mimicking material 34 Bibliogr
14、aphy36 Figure 1 Schematic representation of a thermal test assembly14 Figure 2 Schematic representation of a thermal sensor test object15 model in each case .15 an unfocused Gaussian beam of 6 dB radius 0,1 mm to 10 mm .18an unfocused Gaussian beam of 6 dB radius 0,1 mm to 10 mm .18 Table B.1 Clinic
15、al models .19 objects20 Table B.3 Standard physical tissue models.22 INTRODUCTION This Technical Specification specifies the design and performance characteristics of test objects for determining temperature rise in medical diagnostic ultrasound fields. It also describes how such test objects can be
16、 used to determine ultrasonically-induced temperature rises from diagnostic equipment. This standard specifically relates to test objects which contain an embedded thermal sensor (such as a thermocouple or thermistor) although some parts may also be relevant to alternative method of temperature dete
17、rmination. The test objects are for the measurement of temperature rise and not for the determination of thermal index which is, by definition, an algebraic combination of acoustical field quantities and is therefore not a physically measurable quantity. 3 DD IEC/TS 62306:2006ULTRASONICS FIELD CHARA
18、CTERISATION TEST OBJECTS FOR DETERMINING TEMPERATURE ELEVATION IN DIAGNOSTIC ULTRASOUND FIELDS 1 Scope This Technical Specification is applicable to medical diagnostic ultrasonic fields. This Technical Specification establishes: the important characteristics and terminology for test objects containi
19、ng an embedded thermal sensor to determine ultrasonic heating; requirements for defining particular types of test object for specific applications; examples of design features which will ensure that the performance specifications are achieved; validation procedures; general test methods for using te
20、st objects to determine standardised temperature rises. NOTE 1 This Technical Specification specifically relates to test objects which contain an embedded thermal sensor (such as a thermocouple or thermistor). Although it may be possible to use non-embedded methods of temperature determination to ac
21、hieve the same ends, these are outside of the scope of this Technical Specification. NOTE 2 The test objects specified in this Technical Specification are for the measurement of temperature rise and not for the determination of Thermal Index which is, by definition, an algebraic combination of acous
22、tical field quantities and is therefore not a physically measurable quantity. 2 Normative references 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 refe
23、renced document (including any amendments) applies. IEC 61102:1991, Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range of 0,5 MHz to 15 MHz IEC 61157:1992, Requirements for the declaration of the acoustic output of medical diagnostic ultrasonic equipment I
24、EC 61161, Ultrasonic power measurement in liquids in the frequency range 0,5 MHz to 25 MHz 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 4 DD IEC/TS 62306:20063.1 acoustic coupling medium material placed between different parts of a thermal tes
25、t assembly in order to maintain acoustic transmission 3.2 acoustic working frequency arithmetic mean of the frequencies f1and f2at which the amplitude of the spectrum of the acoustic signal, i.e. the output of a hydrophone placed in an acoustic field at a specified position, first becomes 3 dB lower
26、 than the peak amplitude Conforms to definition 3.4.2 of IEC 61102. Symbol: fawfUnit: megahertz, MHz. 3.3 backing region region of a thermal sensor test object between the target region and the back surface of the thermal sensor test object enclosure 3.4 calibration factor ratio of the temperature r
27、ise, measured for a particular thermal sensor test object, to the reference temperature rise for that type of thermal sensor test object Symbol: FcUnits: dimensionless 3.5 clinical model a term used to specify a clinical application of diagnostic ultrasound which is represented by a physical tissue
28、model 3.6 entrance window outer surface region of the thermal sensor test object that interfaces with the simulated tissue path 3.7 incremental transmission loss coefficient for a specified physical tissue model, the increase in transmission loss of the tissue-simulating material between the face of
29、 the probe and the point of interest per unit increase in the distance between the probe face and the point of interest, divided by the acoustic working frequency at which the transmission loss is determined Symbol: LincUnit: decibel per centimetre per megahertz, dB cm1MHz13.8 measured temperature r
30、ise temperature increase measured in a thermal sensor test object after the standard insonation time 5 DD IEC/TS 62306:20063.9 minimum distance for a specific physical tissue model, the minimum allowed value of the separation between the probe face and the point of interest. This value depends on th
31、e clinical application Symbol: doUnit: metre, m. 3.10 minimum transmission loss for a specific physical tissue model, the transmission loss at the minimum distance of the tissue-simulating material between the probe face and the point of interest Symbol: L0Unit: decibel per megahertz, dB MHz1. 3.11
32、physical tissue model a layered model representation of the physical characteristics, such as the transmission loss and the thermal conductivity, of a particular clinical model of ultrasound under reasonable worst-case conditions 3.12 point of interest the particular point in a physical tissue model
33、 at which the temperature rise is to be determined 3.13 primary junction that part of a thermocouple-based thermal sensor that converts the local temperature increase to an electrical potential. It should normally be placed at the point of interest 3.14 probe those parts of medical ultrasound diagno
34、stic equipment comprising the ultrasonic transducer and/or ultrasonic transducer element group together with any integral components, such as an acoustic lens or integral stand-off. The probe is usually separable from the ultrasonic instrument console IEC 61157, definition 3.22, modified 3.15 refere
35、nce temperature rise a temperature increase specified for a particular type of thermal sensor test object, used in calibrating a practical implementation of the thermal sensor test object under specified insonation conditions Symbol: TrefUnits: degree Celsius, C. 3.16 reference transducer transducer
36、 with specified properties and output characteristics that is used for validating the conformance of a thermal sensor test object with its specification 6 DD IEC/TS 62306:20063.17 residual transmission loss for a specified physical tissue model, the transmission loss at the minimum distance of the t
37、issue-simulating material between the probe face and the surface of a thermal sensor test object Symbol: LrUnit: decibel per megahertz, dB MHz1. 3.18 secondary junctions any part (except for the primary junction) of a thermocouple-based thermal sensor that converts the local temperature increase to
38、an electrical potential. For certain thermocouple configurations, including thin-film thermocouples, the secondary junctions are the connections between the thermocouple and the main leads that conduct the signal away from the thermocouple assembly 3.19 simulated target tissue any tissue-simulating
39、material in the target region of a physical tissue model 3.20 simulated tissue path path of variable depth between the face of a probe and the surface of the target region which has a transmission loss determined from the residual transmission loss and the incremental transmission loss coefficient o
40、f a particular physical tissue model 3.21 standard insonation time the period over which the reference temperature rise is to be measured, defined here as 3 min (180 s) 3.22 target plane plane within the target region, normally perpendicular to the direction of propagation of the ultrasound beam, in
41、 which the point of interest lies 3.23 target region region that surrounds the point of interest (normally within 5 mm to 10 mm of the point of interest). The target region may contain one or more simulated target 3.24 thermal sensor device that measures a temperature increase, usually by converting
42、 it to an electrical signal NOTE An effective thermal sensor in diagnostic ultrasound fields needs to introduce minimal interaction with the ultrasound beam and have a suitably small spatial and thermal resolution. 3.25 thermal sensor test object test object containing the target region and a therma
43、l sensor NOTE The thermal sensor test object may also contain other components, for example, the backing region. 7 DD IEC/TS 62306:20063.26 thermal sensor test object enclosure outer enclosure of the thermal sensor test object, which includes the entrance window 3.27 thermal test assembly apparatus
44、incorporating a thermal sensor test object and a simulated tissue path and configured to a specified physical tissue model or worst-case model 4 List of symbols d distance between the face of a probe and the point of interest. d0minimum distance between the face of a probe and the point of interest.
45、 fawfacoustic working frequency. Fccalibration factor. h thickness of material used to provide the attenuation for a simulated tissue path. k0thermal conductivity of medium in target region. k1, k2thermal conductivities of thermocouple leads. thermal diffusivity of the target region. lpdistance betw
46、een the face of a probe and the point of maximum pulse pressure squared integral. L transmission loss of material used for a simulated tissue path. Lctransmission loss coefficient for material used for a simulated tissue path. Lincincremental transmission loss coefficient of a specified physical tis
47、sue model L0minimum transmission loss of a specified physical tissue model. Lrresidual transmission loss. Lwtransmission loss of an acoustic window as part of a thermal sensor test object. s thermal spatial resolution. T temperature rise. Trefreference temperature rise 5 Thermal test assembly The ge
48、neral configuration for the thermal test assembly is shown in Figure 1. Acoustic coupling between the face of the probe, the simulated tissue path and the thermal sensor test object shall be achieved using water or any other acoustic coupling medium with a characteristic acoustic impedance close to
49、that of water. Different combinations of a thermal sensor test object and a simulated tissue path shall be assembled in order to simulate an appropriate physical tissue model: recommendations are given in Annex B. NOTE 1 If the simulated tissue path is fluid or semi-fluid, there may be no need for separate layers of acoustic coupling medium. 8 DD IEC/TS 62306:2006NOTE 2 Although this Technical Specification considers the simulated tissue path and the thermal sensor test object as being separate, there may be some
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