Already a subscriber? 
MADCAD.com Free Trial
Sign up for a 3 day free trial to explore the MADCAD.com interface, PLUS access the
2009 International Building Code to see how it all works.
If you like to setup a quick demo, let us know at support@madcad.com
or +1 800.798.9296 and we will be happy to schedule a webinar for you.
Security check
Please login to your personal account to use this feature.
Please login to your authorized staff account to use this feature.
Are you sure you want to empty the cart?
PD IEC/TR 62799:2013 Models for evaluation of thermal hazard in medical diagnostic ultrasonic fields, 2013
- 30290917-VOR.pdf [Go to Page]
- CONTENTS
- FOREWORD
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 Background [Go to Page]
- 4.1 General
- 4.2 Limitations of the existing standard [Go to Page]
- 4.2.1 Linear display
- 4.2.2 Equilibrium temperature
- 4.2.3 Tissue parameters
- 4.2.4 Transducer self-heating
- 4.2.5 Safety limits
- 5 Options for improvement of the existing standard [Go to Page]
- 5.1 General
- 5.2 Exponential display of the current TI [Go to Page]
- 5.2.1 Theory
- 5.2.2 Illustrative results for the new thermal index display
- 5.2.3 Advantages of the new display
- 5.2.4 Shortcomings of the new display
- 5.3 Replacement of the TI with the thermally equivalent time index (TETI) [Go to Page]
- 5.3.1 Theory
- 5.3.2 Illustrative results for the TETI
- 5.3.3 Advantages of the TETI
- 5.3.4 Shortcomings of the TETI
- 5.4 Replacement of the TI with the time to threshold (TT) [Go to Page]
- 5.4.1 Theory
- 5.4.2 Illustrative results for the TT
- 5.4.3 Advantages of the TT
- 5.4.4 Shortcomings of the TT
- 5.5 Replacement of the TI with the safe use time (SUT) [Go to Page]
- 5.5.1 Theory
- 5.5.2 Illustrative results for the SUT
- 5.5.3 Advantages of the SUT
- 5.5.4 Shortcomings of the SUT
- 5.6 Replacement of the TI with the thermally equivalent time displayed (TETD) [Go to Page]
- 5.6.1 Theory
- 5.6.2 Illustrative results for the TETD
- 5.6.3 Advantages of the TETD
- 5.6.4 Shortcomings of the TETD
- 6 Summary
- 7 Recommendations [Go to Page]
- 7.1 General
- 7.2 Thermally equivalent time index
- 7.3 Other models
- Bibliography
- Figures [Go to Page]
- Figure 1 – Comparison of the values of thermal index that would be displayed under the proposed definition, TInew, with that displayed currently, TIcur
- Figure 2 – Expanded view of the comparison of Figure 1 for smaller values of TIcur
- Figure 3 – Thermal-equivalent core temperature elevations vs time
- Figure 4 – Temperature-time curve (solid line) that represents a conservative boundary for non-foetal exposure durations, particularly for exposure durations of less than 5 s
- Figure 5 – Thermally equivalent time index (solid curves) vs foetal exposure duration for TI = 1, 2, 3 and 4
- Figure 6 – Temperature rise for distance (z0 > 3 cm) for four models
as a function of US exposure time
- Figure 7 – Relation between TT (time to threshold) and power parameters that give a
temperature rise of ΔTthr = 4 °C
- Figure 8 – The ratio of temperature rise to acoustic absorption coefficient, ΔT/μ , vs exposure duration for the non-scanning soft tissue model with Pa = 100 mW
- Figure 9 – A typical example of temperature rise due to diagnostic ultrasound
- Figure 10 – Values of temperature rise as a function of insonation time
- Figure 11 – The thermal load as a function of time and f-number
- Figure 12 – A comparison of thermally equivalent times (t43) for the temperature profiles shown in Figure 6
- Figure 13 – Probability of birth defect or kidney necrosis as a function of thermally equivalent time (t43)
- Figure 14 – Probabilities of kidney necrosis estimated for the thermally equivalent times (t43) shown in Figure 12
- Figure 15 – Probabilities of birth defect estimated for the thermallyequivalent times (t43) shown in Figure 12
- Tables [Go to Page]
- Table 1 – Thermally equivalent time thresholds for chronic damage in various tissues, t43; see [21].
- Table 2 – Foetal exposure durations for a thermally equivalent time index value of 1
- Table 3 – Non-foetal exposure durations for a thermally equivalent time index value of 1
- Table 4 – SUT values when including and ignoring the contribution of
temperatures lower than ΔTmax for the four exposure conditions and
the corresponding values of ΔTmax
- Table 5 – Values of W, Wa, and ΔTmax for the case of SUT = 500 s.
- Table 6 – Comparison of significant characteristics of the possible replacements for the TI. [Go to Page]
