prEN IEC 63440:2025

SLOVENSKI STANDARD
01-december-2025
Ultrazvok - Merjenje dviga temperature, ki ga povzroča medicinska ultrazvočna
oprema
Ultrasonics - Measurement of temperature rise produced by medical ultrasonic
equipment
Ultrasons - Mesurage de l'élévation de température produite par les appareils médicaux
à ultrasons
Ta slovenski standard je istoveten z: prEN IEC 63440:2025
ICS:
17.140.50 Elektroakustika Electroacoustics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

87/916/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 63440 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-10-24 2026-01-16
SUPERSEDES DOCUMENTS:
87/883/CD, 87/889A/CC
IEC TC 87 : ULTRASONICS
SECRETARIAT: SECRETARY:
United Kingdom Mr Petar Luzajic
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
SC 62B,SC 62D
ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
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the final stage for submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Ultrasonics - Measurement of temperature rise produced by medical ultrasonic equipment

PROPOSED STABILITY DATE: 2029
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IEC CDV 63440 © IEC 2025
1 CONTENTS
3 FOREWORD . 5
4 INTRODUCTION . 7
5 1 Scope . 8
6 2 Normative references . 8
7 3 Terms and definitions . 8
8 4 List of Symbols . 11
9 5 Measurement of patient contact surface temperature for Diagnostic Ultrasound . 12
10 5.1 12
11 5.1.1 Thermal sensor types . 12
12 5.1.2 Spatial averaging and heat dissipation . 12
13 5.1.3 Measurement resolution and measurement uncertainties . 13
14 5.1.4 Positioning of thermal sensor . 13
15 5.1.5 Environmental chamber and ambient temperature monitoring . 15
16 5.1.6 Sampling Rate . 16
17 5.1.7 Measurement Duration . 16
18 5.1.8 Data to Record . 16
19 5.1.9 Temperature Rise with One-Sensor or Two-Sensor Methods . 17
20 5.1.10 Extrapolation Protocol . 20
21 5.2 Measurements in still air . 24
22 5.2.1 Measurement setup description . 24
23 5.2.2 Calculation of measurement result . 24
24 5.3 Measurements in contact with test object– TMM or BMF (blood mimicking
25 fluid) . 25
26 5.3.1 Measurement setup description . 26
27 5.3.2 Calculation of the measurement result . 33
28 6 Temperature measurements for Physiotherapy Equipment . 34
29 6.1 Treatment Head Test Methods . 34
30 6.1.1 Simulated Use . 34
31 6.1.2 Test Methods . 35
32 6.1.3 Still air . 35
33 6.1.4 Operating Settings . 35
34 6.1.5 Temperature Measurement . 35
35 Annex A (informative)  Reference Temperature Chamber . 37
36 A.1 General . 37
37 Annex B (informative)  Measurement uncertainty and accuracy . 39
38 Annex C (informative)  TMM and BMF Recipes . 40
39 C.1 General . 40
40 C.2 Preparation of the soft TMM [17] . 40
41 C.2.1 Recipe to prepare the soft TMM and the set-up . 41
42 C.2.2 Maintenance . 41
43 C.3 Preparation of glycerol blood-mimicking fluid BMF . 42
44 C.3.1 Recipe to prepare the blood-mimicking fluid and setup . 42
45 C.3.2 Maintenance . 43
46 C.4 Preparation of polyurethane blood-mimicking fluid BMF [15] . 43
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47 C.4.1 Recipe to prepare the polyurethane blood-mimicking fluid and setup . 43
48 C.4.2 Maintenance . 43
49 Annex D (informative)  Measurement procedure of the transducer surface temperature
50 in still air using an infra-red camera . 46
51 D.1 General . 46
52 D.2 Measurement setups . 46
53 D.3 Procedures . 47
54 Annex E (informative)  Measurement Methods a) and b) at Different Ambient
55 Temperatures . 50
56 E.1 General . 50
57 E.2 Figures for Further Clarification. 50
58 Annex F (informative)  Workflow for Temperature or Temperature Rise Measurement . 54
59 F.1 General . 54
60 F.2 Temperature Measurement Workflow . 54
61 F.3 F.3 Key Points of Temperature Measurement in Each Process . 55
62 F.3.1 General . 55
63 F.3.2 The Type of Measurement Required in Each Process . 55
64 F.3.3 Report of Measurement Required . 56
65 F.3.4 Summary . 56
66 F.4 How to Use Estimation Methods for Determining Thermal Steady State . 56
67 F.4.1 General . 56
68 F.4.2 Features of Estimation Methods . 56
69 F.4.3 How to Use Estimation Methods . 57
70 Annex G (informative) Future Considerations . 59
71 G.1 General . 59
72 Bibliography . 60
74 Figure 1 – hot spot location determination with infrared camera image . 15
75 Figure 2 – off-centered hot spot location . 16
76 Figure 3 – still-air measurement setup example . 17
77 Figure 4 – visualization of measurement methods and measurement evaluation
78 methods . 20
79 Figure 5a – Example of three consecutive measurements using the two-sensor
80 method. The time, t, corresponds to 30 min per measurement with no cooling between
81 measurements. . 21
82 Figure 5b – Example of three consecutive measurements (orange lines) using the two-
83 sensor method with no cooling between measurements and shortened measurement
84 times and extrapolated values. 22
85 Figure 5c – Example of three consecutive measurements using the two-sensor
86 method. The time, t, corresponds to 30 min per measurement with transition periods of
87 1 min between transmit conditions. . 23
88 Figure 5d – Example of three consecutive measurements (orange lines) using the two-
89 sensor method with transition periods of 1 min between transmit conditions and
90 showing shortened measurement times and extrapolated values. . 24
91 Figure 6 – measurement cycle with output hold at the beginning and a 30-minutes
92 measurement after the initial thermal steady state condition is reached for several
93 consecutive measurements using one or two sensors . 24
94 Figure 7 – Graphical depiction of calculation of ∆T (t) . 26
3,X
95 Figure 8 – Example of temperature measurement for a closed-loop system that
96 decreases output during a measurement, with (a) 30-minute measurement, and (b) 24-
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97 minute measurement and extrapolation. In both cases, the maximum temperature is
98 43,0°C. . 28
99 Figure 9 – Example of shear wave elastography temperature measurement with
100 significant fluctuations . . 29
101 Figure 10 – Example of different amount of coupling gel used for large footprint and
102 small footprint transducer assemblies . 33
103 Figure 12 – Example of a setup with a heated TMM for external transducer assemblies . 35
104 Figure 13 – Example of a setup with heated TMM for internal transducer assemblies . 35
105 Figure 14 – Example of a setup with unheated TMM for external transducer
106 assemblies; left: one-sensor method; right: two-sensor method . 36
107 Figure 15 – Example of a setup with unheated TMM for internal transducer assemblies;
108 left: one-sensor method; right: two-sensor method . 36
109 Figure 16 – Set up of a heated TMM with an internal transducer assembly and two-
110 sensor method (left sensor is the dummy sensor and the right sensor is the sensor on
111 the applied part) . 37
112 Figure 16 – Example of a setup with a single unheated flat-shaped TMM in two-sensor
113 method for intraoperative transducer assemblies . 38
114 Figure 17 – Example of a setup with unheated TMM using two TMMs in two-sensor
115 method . 39
116 Figure A.1 – Illustration of a thermocouple . 45
117 Figure A.2 – Ice point chamber [12] . 45
118 Figure A.3 – Isothermal chamber [12] . 46
119 Figure C.1 – Set-up of an example test object to measure the surface temperature of
120 externally applied transducers . 50
121 Figure C.2 – Example of a BMF measurement setup with flow and no heating . 52
122 Figure C.3 – Example of a BMF measurement setup with flow and heating . 53
123 Figure D.1 – Measurement setup for the transducer surface-temperature test in still air
124 using an infrared camera . 54
125 Figure D.2 – A cardboard box used as a shield against drafts during actual
126 measurement . 55
127 Figure D.3 – Flow chart of the transducer surface temperature test in still air using an
128 infrared camera . 57
129 Figure E.1 – left: method b) for an external transducer assembly with heat sources;
130 right: method b) for an external transducer assembly without heat sources . 58
131 Figure E.2 – left: method a) for an external transducer assembly with heat sources;
132 right: method a) for an external transducer assembly without heat sources . 59
133 Figure E.3 – left: method b) for an external transducer assembly with heat sources at
134 room temperature; right: method b) for an external transducer assembly without heat
135 sources at room temperature . 60
136 Figure F.1 – The workflow of Series of Temperature Measurement Processes . 62
138 Table 1 – Temperature Change Threshold Criteria for earliest Stop Time (during the
139 heating period). 27
140 Table 2 – Temperature Extrapolation Protocols for ∆T3,X and m3,X. 27
141 Table C.1 – Acoustic and thermal properties of tissues & materials [17] . 48
142 Table C.2 – Weight % pure components [17]. 49
143 Table C.3 – Weight % pure components . 51
144 Table F.1 – The Key Points of Temperature Measurement in Each Process . 64
145 Table F.2 – Features of Estimation Methods . 65
IEC CDV 63440 © IEC 2025
146 Table F.3 – How to Use Estimation Methods . 66
IEC CDV 63440 © IEC 2025
149 INTERNATIONAL ELECTROTECHNICAL COMMISSION
150 ____________
152 ULTRASONICS – MEASUREMENT OF TEMPERATURE RISE PRODUCED
153 BY MEDICAL ULTRASONIC EQUIPMENT
158 FOREWORD
159 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
160 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
161 co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
162 in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
163 Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
164 preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
165 may participate in this preparatory work. International, governmental and non-governmental organizations liaising
166 with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
167 Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
168 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
169 consensus of opinion on the relevant subjects since each technical committee has representation from all
170 interested IEC National Committees.
171 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
172 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
173 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
174 misinterpretation by any end user.
175 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
176 transparently to the maximum extent possible in their national and regional publications. Any divergence between
177 any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
178 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
179 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
180 services carried out by independent certification bodies.
181 6) All users should ensure that they have the latest edition of this publication.
182 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
183 members of its technical committees and IEC National Committees for any personal injury, property damage or
184 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
185 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
186 Publications.
187 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
188 indispensable for the correct application of this publication.
189 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
190 rights. IEC shall not be held responsible for identifying any or all such patent rights.
191 IEC 63440 has been prepared by IEC technical committee 87: Ultrasonics. It is an International
192 Standard.
193 The text of this International Standard is based on the following documents:
FDIS Report on voting
XX/XX/FDIS XX/XX/RVD
195 Full information on the voting for the approval of this International Standard can be found in the
196 report on voting indicated in the above table.
197 This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
198 In this particular standard, the following print types are used:
IEC CDV 63440 © IEC 2025
199 – requirements, compliance with which can be tested, and definitions: in roman type
200 – NOTEs, explanations, advice, introductions, general statements, exceptions, and references: in
201 smaller type
202 – test specifications: in italic type
203 - words in bold are defined terms in Clause 3
204 The committee has decided that the contents of this document will remain unchanged until the
205 stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
206 the specific document. At this date, the document will be
207 • reconfirmed,
208 • withdrawn,
209 • replaced by a revised edition, or
210 • amended.
212 The National Committees are requested to note that for this document the stability date
213 is 20XX.
214 THIS TEXT IS INCLUDED FOR THE INFORMATION OF THE NATIONAL COMMITTEES AND WILL BE DELETED
215 AT THE PUBLICATION STAGE.
IEC CDV 63440 © IEC 2025
217 INTRODUCTION
218 This International Standard applies to medical ultrasonic equipment, including diagnostic
219 ultrasound and ultrasound physiotherapy equipment. This standard specifies the measurement
220 methods, calculations, requirements and guidelines for validating that maximum patient-applied
221 part temperature complies with limits in safety standards or regulatory guidances. It describes
222 how temperature sensors and test objects can be used to determine ultrasonically induced
223 temperature rise. This standard allows the determination and use of extrapolated temperature
224 in order to reduce measurement time in-lieu of measuring to the standard 30 minutes. For
225 medical ultrasonic equipment operating conditions meeting requirements herein, extrapolation
226 can begin once the temperature rise has reached stability thresholds. It also describes
227 determining temperature rise using one or two sensors. The characteristics of tissue-mimicking
228 and blood-mimicking phantoms to be used in this testing are described.
IEC CDV 63440 © IEC 2025
231 ULTRASONICS – MEASUREMENT OF TEMPERATURE RISE PRODUCED
232 BY MEDICAL ULTRASONIC EQUIPMENT
237 1 Scope
238 This International Standard is applicable to medical ultrasonic equipment capable of inducing a
239 temperature rise at the patient contact surface.
240 This International Standard is meant to support the safety standards through providing the
241 details of temperature measurements necessary to confirm with safety requirements therein
242 and establishes:
243 • the important characteristics, calculations and terminology for determining temperature
244 rise for diagnostic and physiotherapy ultrasound equipment;
245 • requirements for temperature rise measurements for each type of medical ultrasound
246 equipment;
247 • general test methods for still air and using test objects to determine standardized
248 temperature;
249 • validation procedures.
250 This International Standard does not address methods for simulation of temperature.
251 2 Normative references
252 The following documents are referred to in the text in such a way that some or all of their content
253 constitutes requirements of this document. For dated references, only the edition cited applies.
254 For undated references, the latest edition of the referenced document (including any
255 amendments) applies.
256 IEC 60601-2-37:2024 Medical electrical equipment – Part 2-37: Particular requirements for the
257 basic safety and essential performance of ultrasonic medical diagnostic and monitoring
258 equipment
259 IEC 60601-2-5:2009, “Medical electrical equipment - Part 2-5: Particular requirements for the
260 basic safety and essential performance of ultrasonic physiotherapy equipment.
261 IEC 60601-2-62:2013, “Medical electrical equipment - Part 2-62: Particular requirements for the
262 basic safety and essential performance of high intensity therapeutic ultrasound (HITU)
263 equipment”
264 3 Terms and definitions
265 For the purposes of this document, the following terms and definitions apply.
266 For the purposes of this document, the terms and definitions given in IEC 60601-2-5, IEC 60601-
267 2-37 and IEC 60601-2-62 apply.
IEC CDV 63440 © IEC 2025
268 ISO and IEC maintain terminological databases for use in standardization at the following
269 addresses:
270 • IEC Electropedia: available at http://www.electropedia.org/
271 • ISO Online browsing platform: available at http://www.iso.org/obp
272 3.1
273 ambient temperature
274 temperature of air in the vicinity of the device under test
o
276 Note 1 to entry: Ambient temperature is expressed in degree Celsius ( C).
277 Note 2 to entry: During the measurement of the ambient temperature, the measuring instrument or transducer
278 assembly should be shielded from draughts and radiant heating.
279 [Source: from IEV 845-27-110]
280 3.2
281 applied part
282 part of medical ultrasonic diagnostic equipment or medical ultrasonic physiotherapy
283 equipment that in NORMAL USE necessarily comes into physical contact with the
284 PATIENT to perform its function
285 [SOURCE: IEC 60601-1 ed, modified: ME EQUIPMENT or ME SYSTEM is replaced by medical
286 ultrasonic diagnostic equipment and medical ultrasonic physiotherapy equipment]
287 3.3
288 average three-minute temperature change
289 ∆T3,X(t)
290 the average temperature rise or fall over a specified time of not less than 3 minutes, calculated
291 from at least 10 samples, where the time, X, shall be greater than or equal to 1 minute and be
292 specified, and time t is in the center of the time window t ± (3+X)/2
293 Note 1 to entry: An X value greater than or equal to 1 minute corresponds to a data calculation window of greater
294 than or equal to 4 minutes
296 3.4
297 Closed-loop power adjustment system
298 The ultrasound system, independent of the operator, automatically adjusts transmit-related
299 parameters which affect acoustic or thermal output.
301 Note 1 to entry: Examples include ultrasound systems which monitor probe temperature and automatically increase
302 or decrease Tx voltage or other Tx-related parameters to increase or decrease probe temperature.
303 Note 2 to entry: Refer to subclause 5.1.10 for specific instructions on the use of extrapolation on closed loop
304 adjustment systems.
305 3.5
306 cooling period
307 the time period when the acoustic power is 'off' (i.e., the transducer elements are non-
308 energized)
309 Note to entry: a thermal offset may still remain at the end of the cooling period
310 3.6
311 extrapolated 30-minute temperature or extrapolated 30-minute temperature rise
312 T (t) or ∆ p(t)
30,LinExtrp T30,LinExtr
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313 estimated temperature or temperature rise at 30 minutes extrapolated from temperature data
314 at times earlier than 30 minutes
315 3.7
316 heating period
317 the period when the transducer assembly and all relevant electronics are being electrically
318 excited equivalent to typical clinical use of the ultrasound transducer assembly
319 3.8
320 hot spot
321 the position on the applied part of the transducer assembly where the spatial peak
322 temperature is observed
323 3.9
324 invasive transducer assembly
325 transducer which, in whole or in part, penetrates inside the body, either through a body orifice
326 or through the surface of the body
327 Note 1 to entry: Invasive transducer assemblies include cavity transducers (transoesophageal echocardiography
328 or TEE, trans vaginal or TV, transrectal, or laparoscopy), catheter transducers (intracardiac cardiac
329 echocardiography or ICE, intravascular ultrasound or IVUS, or intravascular echocardiography), and intraoperative
330 transducers used in an invasive manner.
331 [SOURCE: IEC 60601-2-37 2024, definition 201.3.207]
332 3.10
333 Linear-fit temperature slope
334 m
3,X
335 slope of a linear least-squares fit to temperature over a specified time of not less than 3 minutes,
336 where the additional time X shall be specified
337 Note 1 to entry: The linear fit equation is T=m *t + q , where T is temperature, t is time
3,X 3,X
338 Note 2 to entry: An X value greater than or equal to 1 minute corresponds to a data calculation window of greater
339 than or equal to 4 minutes
341 3.11 Linear-fit temperature intercept
342 q
3,X
343 intercept of a linear least-squares fit to temperature over a specified time of not less than 3
344 minutes, where the additional time X shall be specified
345 Note 1 to entry: The linear fit equation is T=m *t + q , where T is temperature, t is time
3,X 3,X
346 Note 2 to entry: An X value greater than or equal to 1 minute corresponds to a data calculation window of greater
347 than or equal to 4 minutes
349 3.12
350 thermal steady state
351 condition where temperature does not change over time
352 Note 1 to entry: For the purposes of this standard thermal steady state is approximated by a temperature change
353 over a three minute period that is less than or equal to 1,0% of the following values: in still air, 27,0 C; in simulated
354 use with external transducers, 10,0 C; in simulated use with invasive transducers, 6,0 C. These values come from
355 the IEC 60601-2-37 limits for air and for simulated use method B.
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356 3.13
357 thermal offset
358 ΔToffset
359 difference between a) the temperature of the APPLIED PART of the TRANSDUCER ASSEMBLY
360 at steady state in the measurement setting before transmitting begins and b) the steady state
361 temperature at the same location in the measurement setting when the TRANSDUCER
362 ASSEMBLY was not present
363 Note 1 to entry: The value of the thermal offset can be positive, negative or zero.
364 Note 2 to entry: The thermal offset is defined at the thermal steady state condition.
365 [SOURCE: IEC 60601-2-37 ed. 3]
366 3.14
367 tissue-mimicking material
368 TMM
369 a material that is constructed to have acoustic and thermal properties similar to those of human
370 tissue
371 3.15
372 transducer assembly
373 those parts of medical diagnostic ultrasonic equipment comprising the ultrasonic transducer
374 and/or ultrasonic transducer element group, together with any integral components, such as an
375 acoustic lens or integral stand-off
376 Note 1 to entry: A transducer assembly is also referred to as a treatment head or applicator.
377 Note 2 to entry: The transducer assembly is usually separable from the ultrasound instrument control.
378 3.16
379 two-sensor systematic temperature difference
380 temperature difference between the applied part sensor and the reference sensor used in the
381 two-sensor method, due to sensor calibration differences and location differences
383 3.17
384 ultrasound
385 acoustic oscillation whose frequency is above the high-frequency limit of audible sound (about
386 20 kHz)
387 [SOURCE: IEV 802-01-01]
388 3.18 ultrasound instrument console
389 electronic unit to which the transducer assembly is attached
391 4 List of Symbols
392 ∆T3,X  average three-minute temperature change
393 T (t) extrapolated 30-minute temperature
30,LinExtrp
395 ∆T (t) extrapolated 30-minute temperature rise
30,LinExtrp
397 m  Linear-fit temperature slope
3,X
398 q3,X  Linear-fit temperature intercept
IEC CDV 63440 © IEC 2025
400 ΔToffset  thermal offset
401 TMM  tissue-mimicking material
403 5 Measurement of patient contact surface temperature for Diagnostic
404 Ultrasound
405 Methods applicable to both air and test-object measurements
406 5.1
407 5.1.1 Thermal sensor types
408 The temperature of the applied part of the transducer assembly should be measured with a
409 thermal measurement device, such as a thermocouple or an infrared camera.
410 5.1.2 Spatial averaging and heat dissipation
411 The size of the temperature measurement area of the sensor should be such that any averaging
412 effect is minimized. For an infrared measurement system, the focus size, the pixel size of the
413 thermal images and the depth of field should be such that any averaging effect is minimized.
415 Figure 1 – hot spot location determination with infrared camera image
416 When using a scanning pyrometer, ensure that the sensor size and spatial step size are
417 sufficient to capture the hot spot and reduce spatial averaging.
418 When using a thermocouple, the impact of heat dissipation can be reduced by using thin wires
419 which are thermally isolated behind the thermocouple junction. The wire diameter shall be less
420 than 0,25 mm in case of round wires and the cross-section area should be less than 0,05 mm²
421 for non-circular wires (e.g. most thin film thermocouples). The sensor wires shall be oriented
422 such that the shortest distance is used to get off the applied part of the transducer assembly
423 (mostly in elevation direction for diagnostic ultrasound transducer assemblies).
424 NOTE 1: The use of thermocouples could result in viscous heating contributions, especially when using invasive
425 transducer assemblies due to the presence of surrounding materials (e.g., tissue -mimicking material or tissue) [1].
426 Corrections may be applied to account for viscous heating. Examples of how to estimate it can be found in [ 2-6].
IEC CDV 63440 © IEC 2025
428 5.1.3 Measurement resolution and measurement uncertainties
429 According to IEC 60601-2-37, the measurement uncertainties shall be determined and recorded
430 according to the principles established in [7]. These uncertainties shall be recorded in the test
431 report. For additional details see Annex B.
432 The measurement uncertainty shall be evaluated for absolute temperature measurements in
433 simulated use method a, and for relative temperature measurements in air and simulated use
434 method b (see clause 5.1.9 for description of methods a and b).
o
435 The temperature measurement resolution should be less than or equal to 0,1 C.
436 NOTE 1: Temperature rise measurements using the same sensors or the same acquisition
437 equipment to measure each temperature may cancel errors that occur with a single, absolute
438 measurement of temperature.
439 If uninsulated thermocouples are used in an electrically conductive liquid, the impact on
440 temperature measurement results should be evaluated because the voltage drop caused by
441 electrical conduct might affect the temperature measurement results.
442 NOTE 2: Thermocouples can be more accurate if the thermocouple offset and slope correction are performed for
443 each individual thermocouple.
444 NOTE 3: A reference temperature chamber or an isothermal cold-junction block can be used to improve measurement
445 accuracy. See Annex A- Reference temperature chamber.
446 NOTE 4: Infrared camera measurements require a correction of the material specific infrared emission spectrum for
447 accurate measurements.
448 NOTE 5: Instructions and examples for measurement uncertainty calculation can be found in [7].
449 5.1.4 Positioning of thermal sensor
450 For ultrasonic diagnostic equipment, the hot spot location may change depending on the
451 activated imaging mode. For example, some imaging devices may use a different transmit
452 aperture position of the transducer array in 2D-mode and CW-mode, respectively. When using
453 transducer assemblies with matrix transducer arrays, hot spots may not be centered in the
454 elevation direction depending on the transmission settings.
IEC CDV 63440 © IEC 2025
456 Figure 2 – off-centered hot spot location
458 If transducer assemblies have different hot spots in different imaging modes, each mode
459 shall be measured using its hot spot. For combined modes, the overall hot spot shall be
460 measured. Possible temperature sensor types include infrared camera, thermocouple,
461 thermistor and pyrometer.
462 NOTE: For mechanically rocked transducer assemblies, the hot spot in 3D/4D mode is not always the same as in
463 2D mode.
464 The infrared camera shall be positioned orthogonal to the hot spot. In case of curved
465 transducer assemblies or transducer assemblies with more complex surface shapes where
466 an orthogonal positioning to the whole applied part of the transducer assembly is not possible,
467 the infrared camera shall be positioned approximately orthogonal to the applied part.
468 NOTE 2: The infrared emissivity of the applied part of the transducer assembly may change as a function of the
469 viewing angle to the applied part surface, with maximum emissivity at normal viewing angles to the emitting surface.
470 NOTE 3: A pyrometer can be used to determine the hot spot location, if scanning over the surface of the applied
471 part of the transducer assembly is performed.
472 The thermocouple junction, thermistor or pyrometer measurement point shall be positioned in
473 the centre of the hot spot.
474 If a thermocouple or thermistor is used for ambient temperature measurement, the
475 thermocouple or thermistor shall be positioned with minimum impact on measurement result.
476 A thin thermally isolating stick, where the sensor is positioned on top may be used to press the
477 sensor to the applied part of the transducer assembly (see Figure 3). A small amount of
478 thermal conductivity paste may be used to improve thermal contact.
479 A silicon-based thermal conductivity paste should be used carefully because this could lead to
480 colour change or damage of the transducer surface.
481 The impact on spatial averaging should be considered if a thermal conductivity paste is used.
482 A small diameter spot of paste, approximately the sensor diameter, and a thin layer, should be
483 used - just enough to wet the junction between the transducer assembly and the sensor.
484 The impact of thermal conductivity paste on measurement results should be evaluated. Some
485 thermal conductivity pastes are electroconductive, which can impact measurement results if the
486 thermocouple junction or thermocouple wires are not isolated.
487 NOTE 4: Measurement procedure of the transducer surface temperature in still air using an infrared camera is
488 described in Annex D as informative.
IEC CDV 63440 © IEC 2025
491 Figure 3 – still-air measurement setup example
493 Alternatively, a thin narrow adhesive insulating tape may be used to position the sensor at the
494 hot spot location. An air gap between the tape and sensor should be avoided.
495 In TMM measurements, a sensor may be fixed on the TMM, and the transducer assembly may
496 be positioned using the ultrasound image, if the device is able to generate 2D or 3D images
497 and the hot spot location is known in the ultrasound image.
498 5.1.5 Environmental chamber and ambient temperature monitoring
499 A direct airflow (e.g., from air conditions) may impact the measurement results and should be
500 avoided. The impact of airflow on measurement results may increase if an active cooling system
501 for the transducer assembly is used.
502 Some ultrasound instrument consoles use fan systems for cooling. If the console is located
503 close to the measurement setup, the emitted warm air could impact the measurement result.
504 The fan systems of the console should be positioned with enough margin for the measurement
505 setup.
506 If an environmental chamber, for example a cardboard or acrylic box, is used to reduce airflow,
507 the chamber may be placed around the transducer assembly.
508 The size of the chamber shall be large enough to avoid a temperature increase of the
509 environmental air due to heat generated from the transducer assembly.
510 The ambient temperature close to the transducer assembly shall be measured during the
511 temperature measurement. An additional temperature sensor may be used, but the position of
512 the sensor shall be enough distance to avoid a direct impact on temperature measurement from
513 heat generated by the transducer assembly.
514 If other parts of the transducer assembly have an impact on the applied part temperature of
515 the transducer assembly (e.g., because of active cooling devices or heat exchangers), they
516 should be in same still-air conditions.
517 The ambient temperature shall be 23,0°C ± 3,0°C.
518 NOTE: Additional heat capacity may be added to the thermocouple junction, if a thermocouple with small size and
519 low heat capacity is used for ambient temperature measurements (e.g., adding a drop of thermal conductivity paste
520 on the thermocouple junction). This reduces the variation of ambient temperature measurement results if the
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