Unapproved Minutes – 8 August 2019 TC95 SC6 Meeting
Approved Minutes
IEEE/ICES TC95 Subcommittee 6 EMF Dosimetry Modeling
0900 – 1130 h
Thursday, 23 January 2020
Motorola Solution
8000 West Sunrise Blvd, Plantation, FL 33322
1. Call to Order
Chairman called the meeting to order at 0906 h.
2. Introduction of those Present
Each of the attendees introduced her/himself. (See Attachment 1 for the list of attendees.)
3. Approval of Agenda
Following a motion by Colville that was seconded by Chou, the agenda was approved as presented (see
Attachment 2).
4. Approval of the Minutes (January 2018 Meeting)
Following a motion by Ziskin that was seconded by Bailey, the minutes of the 8 August 2019 meeting
have been approved.
5. Chairman’s Report
Hirata began the Chairman’s report on the TF2: Uncertainty of Low-Frequency Dosimetry in Segmented
Models.
6. Working Group Reports
WG1 Report (See Attachment 3)
Co-chair of WG1, Alexandre Legros, provided a progress report on the activities of WG1. First he
introduced the activities of SC6 WG1 and SC3 TF1 and how both are complementary. He proceeded to summarize recommendations/findings of SC6 WG1. One important issue is to distinguish between
stimulation and subthreshold when referring to electro-stimulation. Also, it is needed reconsideration of
phosphenes as a basis of CNS limits, where there is a difference between retinal and brain neuron modulation mechanism. Also, he mentioned the literature review efforts of experimental CNS that may be
a basis to derive rheobase and corner frequencies. Alex also explained the most sensitive frequency for
phosphenes (current studies agreed in the frequency range 16-22 Hz) for transcranial current stimulation.
However, magneto stimulation may have a different sensitive frequency. He suggested that this difference needs to be investigated and clarified. He later summarized ongoing work on vestibular stimulation,
thresholds for magnetophosphenes at different conditions, and EEG source connectivity. Alex mentioned
that experimental thresholds of PNS stimulation will be considered. Also, working memory is an expression for synaptic effects and is a potential key unlock and understand more CNS thresholds. Kuster
commented on difficulties on how these experiments in brain stimulation may be translated to the
safety/standards limits of protection and that may be difficult to come out with thresholds for safety.
Legros said that the mechanisms still needs to be understand (e.g., effects of neuroplasticity of brain network changes by transcranial current stimulation) and could be eventually used. CK commented the
mission of the standard to promote safe use of electromagnetics.
WG4: Exploring the Electrostimulation Threshold in Brain (See Attachment 4)
Unapproved Minutes – 8 August 2019 TC95 SC6 Meeting
Co-Chair, Jose Gomez-Tames, reported recent activities including the consistency of E-field computation and consistency of neuronal models for brain stimulation by transcranial magnetic stimulation exposure.
Also, dosimetry and exposure reference levels were derived using these verified models. The work was
presented at IEEE EMC2019 in Sapporo and published in IEEE T-EMC. An extended inter-comparison is
on-going, where a larger number of conditions are considered (nerve models, head models). Hirata commented that this study showed the conservativeness of the standard when considering CNS activation
in axonal response.
WG5: Definition of Incident Power Density (See Attachment 5)
Walid El Hajj (chair) gave a presentation introducing the definition of incident power density to correlate
surface temperature elevation from 6 GHz to 300 GHz to bridge the gap between IEEE C95.1 standard and the current activity of the JWG12. Also, the uncertainty that originated from the measurement’s
protocol was discussed. Preliminary results of the comparison of power density with measurements were
presented. All the results have been obtained and a technical report is under preparation. Technical report
may be published as IEEE Guidance and general paper.
Hirata further clarified that WG5 motivation is that there is not a clear definition of the power density (i.e., normal component or strength value) and clarification is worth discussing. The technical committee
responsible for Guidance should be further discussed; dependent on the content, scenarios etc. If TC95
committee is responsible for this, more members from TC95 should be involved.
TF2: Uncertainty of Low-Frequency Dosimetry in Segmented Models (See Attachment 6)
Co-chair of TF2, Rashed provide activity progress report that demonstrate the research activities since the
assignment in Aug. 2019. The main result was the study of the induced electric field within skin-to-skin contact region. The present measurement data using magnetic stimulation of the hand in different postures
demonstrate skin-to-skin touching/non-touching. Measurements demonstrate almost consistent values in
the sensation threshold values. Also, he demonstrates modeling algorithm that can be used to change
finger positions in static human models to represent skin touching/non-touching positions. Using different anatomical models, computation results of simulated magnetic stimulation demonstrate significant
increase in the computed electric field at the skin-to-skin regions. From this result inconsistency, it may be
concluded that increase of the electric field can be referred to the poor modeling and limited resolution of
the human skin in the current used human models, therefore, it might not be included within the standard.
7. New Business
SC6 will work together with SC6.
8. Time and Place of Next Meeting
The next SC6 meeting will be held on 20 Jun. 2020 in Oxford.
9. Adjourn
There being no further business, the meeting was adjourned at 11:40 h.
Unapproved Minutes – 8 August 2019 TC95 SC6 Meeting
Attendance List
TC95 SC6 (EMF Modeling and Dosimetry): 25 January 2019, 0900-1100 h
Last Name First Name Affiliation Country IEEE SA Member?
1. Bailey Bill Exponent US Y
2. Bit- Babik Goga Motorola Solutions US Y
3. Bushberg Jerrold UC Davis US Y
4. Butcher Matt Sublight Engineering US Y
5. Chou C-K Independent Consultant US Y
6. Cleveland Robert EMF Consulting US Y
7. Colville Frank US Army PHC US Y
8. Cotton David Waterford Consultants US Y
9. Cvekovic Mario University of Split HR N
10. Diao Yingliang South China Agriculture Univ. CN N
11. Escobar Roel Air Force US Y
12. El Hajj Walid Intel FR
13. Faraone Antonio Motorola Solutions, Inc. US Y
14. Futch James Fla. Dept. Health, Radiation Contrl US N
15. Giles Olin Omni Vision Assoc. US Y
16. Glembo Tyler Intel US Y
17. Gomez-Tames Jose Nagoya Inst of Technology JP
18. Graf Kevin FCC US Y
19. Haes Donald Consultant US Y
20. Harmon Ray DoD/Navy US
21. Hirata Akimasa Nagoya Inst of Technology JP Y
22. Johnson Robert EME Safety US Y
23. Kavet Rob Kavet Consulting LCC US Y
24. Krebs Paul Verizon US
25. Kuster Niels IT’IS Foundation CH Y
26. Laakso Ilkka Aalto University FI
27. Legros Alexandre LHRI CA
28. Maxon David Istrope US Y
29. Miyagi Hiroaki HM Research & Consulting Ltd JP Y
30. Paquin Josee National Defence Canada CA N
31. Poljak Dragan University of Split HR
32. Rashed Essam British University in Egypt EG N
33. Roder Patricia IEEE SA US Staff Liaison
34. Sliney David Johns Hopkins Univ. US Y
35. Tanghe Emmeric Ghent University BE
36. Tarnaud Thomas Ghent University US
ATTACHMENT 1
ATTACHMENT 1
月
Unapproved Minutes – 8 August 2019 TC95 SC6 Meeting
37. Tech Darang Dtech Communications US
38. Tell Ric Richard Tell Associates, Inc. US Y
39. Tong Zijun NEMA US
40. Visser Auke Royal Netherlands Navy NL N
41. Wessel Marvin Global RF Solutions US N
42. Zhao Xun DND/QETE CA
43. Ziskin Marvin Temple University US Y
44. Zollman Peter PZC UK
Unapproved Minutes – 8 August 2019 TC95 SC6 Meeting
Agenda
IEEE/ICES TC95 Subcommittee 6 EMF Dosimetry Modeling
0900 – 1130 h
Thursday, 23 January 2020
Motorola Solutions
8000 West Sunrise Blvd, Plantation, FL 33322
1. Call to Order Hirata
2. Introduction of those Present All
3. Approval of Agenda Hirata
4. Approval of the Minutes (Jan 2019 Meeting) Hirata
5. Call for Patents* Hirata
6. Chairman’s Reports Hirata
7. Working Group Report Hirata
WG1: Uncertainties Related to Electrostimulation Threshold Legros/Laakso
WG4: Exploring the Electrostimulation Threshold in Brain Joseph/Gomez
WG5: Definition of Incident Power Density El Hajj
TF2: Uncertainty of Low-Frequency Dosimetry in Segmented Models Rashed/Diao
8. New Business
9. Date and Place of Next Meeting
10. Adjourn
Participants have a duty to inform the IEEE of holders of essential patent claims if they or their affiliations hold such claims. Check the web link on the agenda for more details. If anyone in this meeting is personally
aware of any patent claims that are potentially essential to implementation of the proposed standard(s) under
consideration by this group and that are not already the subject of an Accepted Letter of Assurance, please
speak to the committee chair today.
ATTACHMENT 2
月
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
IEEE-ICES TC95 Winter Meeting
TF-1 – CNS Magnetic Field Exposure Limits - LFSubcommittee 6 - EMF Dosimetry Modeling
Alexandre Legros – [email protected]
Motorola Solutions Inc.Plantation, Florida21–23 January 2020
Attachment 3
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
Last report in Chandler winter meeting 2018
Status
For SC6 - Uncertainties Related toElectrostimulation Threshold in theELF range
§ Ilkka Laakso (co-chair)§ Alexandre Legros (co-chair)§ Akimasa Hirata§ Hideyuki Matsumoto§ Valerio De Santis§ Pat Reilly§ Tongning Wu§ Dragan Poljak§ Esra Neufeld§ Julien Modolo§ SangWook Park§ Leonardo Angelone§ Maria Iacono§ Kevin Graf
For SC3 - TF1 - CNS MagneticField Exposure Limits - LF
§ Bill Bailey§ Aki Hirata§ Ilkka Laakso§ Julien Modolo§ Alex Legros
Coordinators :
§ JP Reilly§ Rob Kavet
White paper reviewing14 electrophosphene,2 magnetophospheneand 5 dosimetrystudies
Recommendations toreduce uncertainties in
the future
Recommendations on astrategy to update LF
standards
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Document and reduce variability in experimental thresholds for electrophosphene and magnetophosheneperceptions in the entire ELF frequency range
§ Address the heterogeneity in the methods, protocols and exposure characteristics
§ Systematic macro- and micro-dosimetry integrated to experimental studies
§ Use realistic mathematical neuronal models to question the possible mechanisms of action
§ New studies allowing a better understanding of phosphene mechanisms will reduce uncertainty
§ A clarification of the term “electrostimulation” needed:
è Stimulation refers to triggering action potentialsèModulation refers to a (subthreshold) change in membrane potential or a change in oscillation
phase for exampleè subthreshold refers to the incapability of triggering an action potential but NOT to an incapability of
eliciting biological effects
Extensive tDCS/tACS literature to take into account: measurable effects for in situ E-fields < 1 V/m (compilingdosimetry, reported neurophysiological and behavioral effects for example)
Recommendations to reduce uncertainty
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Document experimental thresholds and mechanisms (identify meaningfulvariables/outcomes/biomarkers for reliable response to in situ E-fields)
§ Detailed dosimetry based on anatomical models
§ In situ neuro-computational models verifying the hypotheses
Phosphenes ThresholdBrain NeuromodulationThreshold (determine if
achievable)
Recommendations to reduce uncertainty
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Phosphene synapse modulation = mechanisms specific to the retina (graded potential neurons andribbon synapses) and not corresponding similar effects in the cortex of the brain - structural andfunctional differences
§ Outside of phosphene data, experimental evidence shows CNS effects from electro-stimulation onthe brain at levels well below demonstrable neuro-excitation in situ thresholds
§ Subthreshold CNS effectsè CNS limits should include the review of tDCS and tACS experimentaland clinical studies
§ The short deadline for editing C95.1 precludes adequate review of this literature
§ Therefore, hold CNS revision of C95.1 for implementation, and a longer-term review anddevelopment, with the objective of a more comprehensive CNS revision
Recommendations towards LF revisionShort term
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Reconsider phosphenes as a basis for CNS limits in C95.1:
§ Differences between retinal vs. brain neuro-modulation mechanisms - rationale describing theneurophysiological retinal specificities (in structure and function)
§ Reconsider whether phosphenes per se are adverse, and whether other possibly adversereactions during phosphene experiments are credible (e.g., as suggested by Lövsund and Silny)
§ Further efforts to revise CNS limits should focus on the brain itself whether or not phosphenes arekept as the most sensitive basis for setting limits - Review should be addressed by a continuation ofTF-1 (tDCS/tACS literature), additional membership as needed – Pat contacts Marom Bikson
§ A working definition of “adverse reaction” with respect to CNS exposure is needed. A conservativedefinition might include any demonstrable CNS effect firmly established in-vivo (especially inhumans). A more focused definition of “adverse reaction” for CNS reactions should also beconsidered
Recommendations towards LF revisionLong term
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Note: recent large sample human data the Lawson Group exhibits maximum sensitivity at 20 Hz,compared to 50, 60 and 100 Hz, although lower frequencies untested yet. However, threshold at20 Hz 2-4 times greater compared to Lövsund
§ Further development of CNS limits might result in substantial changes in C95.1 – possiblyinvolving an increase in the limits. This requires a long-term comprehensive review: anysubstantial change will require strong evidence in support of such change
§ The literature review of experimental CNS electrostimulation studies from which one can deriverheobase and corner frequency parameters.
§ This thorough review process needs to allow to reinforce/redefine DRLs and ERL forconsideration in an updated revision
Recommendations towards LF revisionLong term
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ BioEM 2019 in Montpelier
§ D’Arsonval presentation from Pat Reilly
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ BioEM 2019 in Montpellier
§ Plenary on Non-Invasive Brain Stimulation – Bikson and GrossmanMarom Bikson by Pat Reilly on IEEE ICES TF1
§ Workshop on Differences of exposure limits between the new ICNIRPGuidelines and IEEE C95.1 Standard (C-K and Eric conveners, presentationsfrom Chou, Croft, Hirata, Foster and Tell)
§ BioEM2020 in Oxford
§ Plenary on Brain Stimulation from Giulio Ruffini: Towards model-driven transcranial currentstimulation (tES 3.0): physics, physiology, modeling, and clinical applications
§ Plenary on ICNIRP / IEEE A comparison between the recently released IEEE and ICNIRPradiofrequency guidelines/standards: What are the differences, and do they make adifference? – C-K and Rodney
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Recent new relevant activities from WG members§ Ilkka Laakso co-author of published paper:
“To validate the method, Bayesian optimization wasemployed using participants’ binary judgements aboutthe intensity of phosphenes elicited through tACS(0.25 to 1 mA)”
They used different tACS montages and confirmed a most sensitive frequency between 16 Hz and 22 Hzdepending on the montage and a given phase difference in the signals.
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Published paper by R. Croft group involvingLegros
§ Most sensitive frequency a little above 16 HzRemark: frequency preference not consistent between electrically and magnetically induces phosphenes
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ IRPA invitation to chair of the Task Group (TG) on Non-Ionizing Radiations (NIR) of the IRPA(International Radio Protection Association - http://www.irpa.net). The general objective is topromote NIR research from national Associate Societies (AS) towards an internationalRadioprotection audience
§ Ongoing Research projects at Lawson:
§ Vestibular responses to ELF exposures up to 100 mT
§ Subjective Visual Vertical (SVV)§ Whole head exposure and posture§ Local vestibular exposure and posture (study 1 and 2)
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Threshold for magnetophosphene perception
§ Study thresholds - analyses completed, plan to submit to Nature Biomedical engineering§ Paper 2 EEG HR source reconstruction and source connectivity submitted – Journal of
Neural engineering (lead Julien Modolo)§ Frequency response§ Adaptation to the darkness
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Upcoming project in Rennes/Montpellier
§ Grant application to study EEG sourceconnectivity under non-invasive brainstimulations (electric and magnetic) inresting, cognitive and motor tasks (leadJulien Modolo)
§ Upcoming projects at Lawson:
§ Vestibular responses to ELF exposures up to100 mT: Vestibulo-ocular response (pupildilation and/or eyeball rotation, whole headand or Local vestibular exposure, up to 100mT (0-300 Hz)
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Threshold for magnetophosphene perception: Replication study conducted in Montpellier-France
§ Extrapolation to synaptic processes: Test of Working Memory and associated EEG as indicatorsof modulations in synaptic plasticity (through action on LTP and LDP within the STDP paradigm)
§ Experimental Threshold for PNS stimulation a power frequencies (50 and 60 Hz)
SC6 WG1 and SC3 TF1 - common effort to conduct
Integrate recent scientific literature, results from ongoingprojects and the strength of committee members to
reduce scientific uncertainty and to methodicallyreinforce the bases of the rationale for LF standards
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
Thank you for your attention andhappy to be more involved with
SC3!
Alexandre Legros - [email protected]
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
IEEE-ICES TC95 Winter Meeting
TF-1 – CNS Magnetic Field Exposure Limits - LFSubcommittee 6 - EMF Dosimetry Modeling
Alexandre Legros – [email protected]
Motorola Solutions Inc.Plantation, Florida21–23 January 2020
Attachment 3
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
Last report in Chandler winter meeting 2018
Status
For SC6 - Uncertainties Related toElectrostimulation Threshold in theELF range
§ Ilkka Laakso (co-chair)§ Alexandre Legros (co-chair)§ Akimasa Hirata§ Hideyuki Matsumoto§ Valerio De Santis§ Pat Reilly§ Tongning Wu§ Dragan Poljak§ Esra Neufeld§ Julien Modolo§ SangWook Park§ Leonardo Angelone§ Maria Iacono§ Kevin Graf
For SC3 - TF1 - CNS MagneticField Exposure Limits - LF
§ Bill Bailey§ Aki Hirata§ Ilkka Laakso§ Julien Modolo§ Alex Legros
Coordinators :
§ JP Reilly§ Rob Kavet
White paper reviewing14 electrophosphene,2 magnetophospheneand 5 dosimetrystudies
Recommendations toreduce uncertainties in
the future
Recommendations on astrategy to update LF
standards
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Document and reduce variability in experimental thresholds for electrophosphene and magnetophosheneperceptions in the entire ELF frequency range
§ Address the heterogeneity in the methods, protocols and exposure characteristics
§ Systematic macro- and micro-dosimetry integrated to experimental studies
§ Use realistic mathematical neuronal models to question the possible mechanisms of action
§ New studies allowing a better understanding of phosphene mechanisms will reduce uncertainty
§ A clarification of the term “electrostimulation” needed:
è Stimulation refers to triggering action potentialsèModulation refers to a (subthreshold) change in membrane potential or a change in oscillation
phase for exampleè subthreshold refers to the incapability of triggering an action potential but NOT to an incapability of
eliciting biological effects
Extensive tDCS/tACS literature to take into account: measurable effects for in situ E-fields < 1 V/m (compilingdosimetry, reported neurophysiological and behavioral effects for example)
Recommendations to reduce uncertainty
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Document experimental thresholds and mechanisms (identify meaningfulvariables/outcomes/biomarkers for reliable response to in situ E-fields)
§ Detailed dosimetry based on anatomical models
§ In situ neuro-computational models verifying the hypotheses
Phosphenes ThresholdBrain NeuromodulationThreshold (determine if
achievable)
Recommendations to reduce uncertainty
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Phosphene synapse modulation = mechanisms specific to the retina (graded potential neurons andribbon synapses) and not corresponding similar effects in the cortex of the brain - structural andfunctional differences
§ Outside of phosphene data, experimental evidence shows CNS effects from electro-stimulation onthe brain at levels well below demonstrable neuro-excitation in situ thresholds
§ Subthreshold CNS effectsè CNS limits should include the review of tDCS and tACS experimentaland clinical studies
§ The short deadline for editing C95.1 precludes adequate review of this literature
§ Therefore, hold CNS revision of C95.1 for implementation, and a longer-term review anddevelopment, with the objective of a more comprehensive CNS revision
Recommendations towards LF revisionShort term
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Reconsider phosphenes as a basis for CNS limits in C95.1:
§ Differences between retinal vs. brain neuro-modulation mechanisms - rationale describing theneurophysiological retinal specificities (in structure and function)
§ Reconsider whether phosphenes per se are adverse, and whether other possibly adversereactions during phosphene experiments are credible (e.g., as suggested by Lövsund and Silny)
§ Further efforts to revise CNS limits should focus on the brain itself whether or not phosphenes arekept as the most sensitive basis for setting limits - Review should be addressed by a continuation ofTF-1 (tDCS/tACS literature), additional membership as needed – Pat contacts Marom Bikson
§ A working definition of “adverse reaction” with respect to CNS exposure is needed. A conservativedefinition might include any demonstrable CNS effect firmly established in-vivo (especially inhumans). A more focused definition of “adverse reaction” for CNS reactions should also beconsidered
Recommendations towards LF revisionLong term
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Note: recent large sample human data the Lawson Group exhibits maximum sensitivity at 20 Hz,compared to 50, 60 and 100 Hz, although lower frequencies untested yet. However, threshold at20 Hz 2-4 times greater compared to Lövsund
§ Further development of CNS limits might result in substantial changes in C95.1 – possiblyinvolving an increase in the limits. This requires a long-term comprehensive review: anysubstantial change will require strong evidence in support of such change
§ The literature review of experimental CNS electrostimulation studies from which one can deriverheobase and corner frequency parameters.
§ This thorough review process needs to allow to reinforce/redefine DRLs and ERL forconsideration in an updated revision
Recommendations towards LF revisionLong term
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ BioEM 2019 in Montpelier
§ D’Arsonval presentation from Pat Reilly
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ BioEM 2019 in Montpellier
§ Plenary on Non-Invasive Brain Stimulation – Bikson and GrossmanMarom Bikson by Pat Reilly on IEEE ICES TF1
§ Workshop on Differences of exposure limits between the new ICNIRPGuidelines and IEEE C95.1 Standard (C-K and Eric conveners, presentationsfrom Chou, Croft, Hirata, Foster and Tell)
§ BioEM2020 in Oxford
§ Plenary on Brain Stimulation from Giulio Ruffini: Towards model-driven transcranial currentstimulation (tES 3.0): physics, physiology, modeling, and clinical applications
§ Plenary on ICNIRP / IEEE A comparison between the recently released IEEE and ICNIRPradiofrequency guidelines/standards: What are the differences, and do they make adifference? – C-K and Rodney
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Recent new relevant activities from WG members§ Ilkka Laakso co-author of published paper:
“To validate the method, Bayesian optimization wasemployed using participants’ binary judgements aboutthe intensity of phosphenes elicited through tACS(0.25 to 1 mA)”
They used different tACS montages and confirmed a most sensitive frequency between 16 Hz and 22 Hzdepending on the montage and a given phase difference in the signals.
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Published paper by R. Croft group involvingLegros
§ Most sensitive frequency a little above 16 HzRemark: frequency preference not consistent between electrically and magnetically induces phosphenes
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ IRPA invitation to chair of the Task Group (TG) on Non-Ionizing Radiations (NIR) of the IRPA(International Radio Protection Association - http://www.irpa.net). The general objective is topromote NIR research from national Associate Societies (AS) towards an internationalRadioprotection audience
§ Ongoing Research projects at Lawson:
§ Vestibular responses to ELF exposures up to 100 mT
§ Subjective Visual Vertical (SVV)§ Whole head exposure and posture§ Local vestibular exposure and posture (study 1 and 2)
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Threshold for magnetophosphene perception
§ Study thresholds - analyses completed, plan to submit to Nature Biomedical engineering§ Paper 2 EEG HR source reconstruction and source connectivity submitted – Journal of
Neural engineering (lead Julien Modolo)§ Frequency response§ Adaptation to the darkness
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Upcoming project in Rennes/Montpellier
§ Grant application to study EEG sourceconnectivity under non-invasive brainstimulations (electric and magnetic) inresting, cognitive and motor tasks (leadJulien Modolo)
§ Upcoming projects at Lawson:
§ Vestibular responses to ELF exposures up to100 mT: Vestibulo-ocular response (pupildilation and/or eyeball rotation, whole headand or Local vestibular exposure, up to 100mT (0-300 Hz)
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
§ Threshold for magnetophosphene perception: Replication study conducted in Montpellier-France
§ Extrapolation to synaptic processes: Test of Working Memory and associated EEG as indicatorsof modulations in synaptic plasticity (through action on LTP and LDP within the STDP paradigm)
§ Experimental Threshold for PNS stimulation a power frequencies (50 and 60 Hz)
SC6 WG1 and SC3 TF1 - common effort to conduct
Integrate recent scientific literature, results from ongoingprojects and the strength of committee members to
reduce scientific uncertainty and to methodicallyreinforce the bases of the rationale for LF standards
Selected news since last report
IEEE ICES TC95 SC3 & SC6 - January 23rd 2020, Plantation
Thank you for your attention andhappy to be more involved with
SC3!
Alexandre Legros - [email protected]
IEEE/ICES TC95
Working Group 4
Exploring the electrostimulation
threshold in brain
Co-chairs:
Wout Joseph (Ghent Univ., Belgium)
Jose Gomez-Tames (NITech, Japan)
Secretary
Emmeric Tanghe (Ghent Univ., Belgium)
ICES 2018
Chandler, USA
January 24, 2018
Slide 2
IEEE ICES
WG4 created in September 17th, 2017.
(SC6 EMF Dosimetry Modeling)
Co-Chair: Wout Joseph (Ghent Univ., Belgium)
Co-Chair: Jose Gomez-Tames (NITech, Japan)
Secretary: Emmeric Tanghe (Ghent Univ., Belgium)
SCOPE: Assessment of brain stimulation threshold by
combined modelling of electromagnetics and CNS neuron
models in LF (“axonal potential generation thresholds”).
WG4: Thresholds in CNS
ICES 2018
Chandler, USA
January 24, 2018
Slide 3
IEEE ICES
3.3 Consistency of excitation model
“How do these models compare? If there are significant differences, on what basis can one be
recommended over another? A recent survey among users of ES models reveals large differences in
predicted excitation thresholds (Reilly 2016).”
3.4 Waveform sensitivity
“How do the existing nerve excitation models compare in this respect?
3.10 Validation
“Computational ES models must be experimentally validated under some representative conditions. It
is important to identify published sources of applicable experimental data, and to make comparisons
with ES model predictions.”
4.8 Statistical models of reaction thresholds
“The statistical distribution of experimental thresholds should be included in validation efforts.”
WG4: Thresholds in CNS
Within the general scope, WG4
considers unresolved issues raised in
the research agenda of the IEEE ICES
(Reilly and Hirata 2016)
ICES 2018
Chandler, USA
January 24, 2018
Slide 4
IEEE ICES
On-going WG4 Activities
1. Consistency of the excitation neurons for
different scenarios.
Stimulation type (TMS)
Uncertainty analysis (Nerve model type,
position/orientation, (An)isotropy, waveform
parameters)
Target (cortical motor area, skin/muscle tissue)
2. Survey of experimental thresholds in neurons.
Statistical distribution of the experimental thresholds
WG4: Thresholds in CNS
ICES 2018
Chandler, USA
January 24, 2018
Slide 5
IEEE ICES
1. Consistency of the excitation neurons for
different scenarios.
WG4: Thresholds in CNS
Two Steps: Induction Model
↓
Electrostimulation model (ES)
Consistency of the E-field computation
Consistency of the neuron models
Comparison of different neuronal models
ICES 2018
Chandler, USA
January 24, 2018
Slide 6
IEEE ICES
Aim: Intercomparison of TMS-induced EF activation for fast-
conducting thickly myelinated pyramidal fibers for corticospinal tracts
Numerical computations (E-field):
•Scalar potential finite difference (SPFD) by Nagoya Institute of Technology, Japan
•Finite element method (FEM) by Ghent University, Belgium
Numerical computations (Nerve activation)
•Spatially extended nonlinear nodal (SENN†) model
•The ionic membrane currents formulated using CRRSS
model
1. CNS thresholds: Intercomparison
† J. P. Reilly, V. T. Freeman, and W. D. Larkin, IEEE Trans. Biomed. Eng, 1985.†† J. D. Sweeney, J. T. Mortimer, and D. Durand, IEEE 97th Annu. Conf. Eng. Med. Biol. Soc. Bost., 1987.
ICES 2018
Chandler, USA
January 24, 2018
Slide 7
IEEE ICES7
1. CNS thresholds: Intercomparison
ICES 2018
Chandler, USA
January 24, 2018
Slide 8
IEEE ICES
The in-situ EF (99.9th percentile) on the gray matter of the hand motor
area was between 100 V/m and 200 V/m for activating axons with lower
thresholds (Laakso 2018, Brain Stimulation)
1. CNS thresholds: Intercomparison
ICES 2018
Chandler, USA
January 24, 2018
Slide 9
IEEE ICES
Agreement between independent model implementations (8% of error)
Difference increases with larger fibers (electric potential along bent axon)
No variation with other nerve parameters (e.g., myelin representation and
temperature)
TABLE II
VERIFICATION OF AXON ACTIVATION BY SENN AND NITECH NERVE AXON
IMPLEMENTATION (N = 90 AXONS)
Metric Value Parameter
(Table A.)
Parameter Variation
D (15 μm) gi
(0 mS/cm2)
T
(18°C)
Threshold
Relative
Error
[%]
Mean 7.7 17.1 7.5 7.6
Std 7.9 15.4 7.5 7.8
Max 24.7 43.3 24.2 24.6
Min 0.2 0.1 0.2 0.1
Position Difference
[mm]
Mean 0.6 0.9 0.6 0.5 Std 0.6 0.5 0.6 0.6
Max 2.1 3.8 2.1 2.1
Min 0.0 0.5 0.0 0.0
Table 2. VERIFICATION OF AXON ACTIVATION BY SENN AND
NITECH AXON IMPLEMENTATION (N = 90 AXONS)
1. CNS thresholds: Intercomparison
ICES 2018
Chandler, USA
January 24, 2018
Slide 10
IEEE ICES
Allowable external magnetic field strength and internal electric
field established in both guidelines/standards derived from PNS
are at least 10 times lower than the one needed for the
stimulation of the CNS
1. CNS thresholds: Intercomparison
ICES 2018
Chandler, USA
January 24, 2018
Slide 11
IEEE ICES
2. CNS thresholds:
Membrane Models Comparison
5 considered “classical” models of the active membrane
Combined with the SENN-model (†)
TMS exposure in hand motor area
Excitation
Threshold
ICES 2018
Chandler, USA
January 24, 2018
Slide 12
IEEE ICES
2. CNS thresholds:
Membrane Models Comparison Excitation thresholds for 251 cortical pyramidal axons
250
50
100
150
200
Max
imum
Inte
rnal
Ele
ctri
c F
ield
[V
/m]
ICES 2018
Chandler, USA
January 24, 2018
Slide 13
IEEE ICES
2. CNS thresholds:
Membrane Models Comparison
Excitation thresholds depend strongly on the used
membrane model
Dependence of excitability on the waveform
e.g., CRRSS model has higher rheobase than the SRB
model but lower chronaxie
Preliminary results indicate the ‘standard’ SENN-model
with HH-dynamics is relatively conservative as
compared with the CRRSS, SE and SRB membrane
models
ICES 2018
Chandler, USA
January 24, 2018
Slide 14
IEEE ICES
Extended Intercomparison
-Whole hand motor area
-Different nerve models
-Different head models
-Anisotropy effects (Electric field computation)
Summary
ICES 2018
Chandler, USA
January 24, 2018
Slide 15
IEEE ICES
Thank you
WG4: Thresholds in CNS
IICCEESS
1
Definition of incident power density to correlate surface temperature
elevation
IEEE/ICES TC95/SC6 in cooperation with TC34
23/01/2020
Dr. Walid EL HAJJ
IICCEESS
2
Outlines
Scope
Rationales behind this WG
Ad-Hoc Groups Presentation
AHG Modeling
AHG Measurement
AHG Thermographic Measurement
Next Steps and Expected Output
IICCEESS
3
Rationales behind the WG
Power Density is the metric used for exposure reference level above 6 GHz
For an exposure limit this quantity is generally spatially and time averaged.
According if the normal component or norm of the Power Density Poyntingvector is used the final metric value will be different, specially in near field and for oblique incidence.
Correlation with the temperature elevation is necessary to decide on the best definition of incident power density
This is the scope of the WG. Output can be used as guide for Health and Safety standards
IICCEESS
4
Scope
Definition of incident power density in the near field is discussed to correlate surface temperature elevation in the frequency range from 6 GHz to 300 GHz by computer simulations to bridge the gap between IEEE C95.1 standard and the current activity of the IEC/JWG12. Additional scientific rationale of the incident power density in the IEEE C95.1 standard is discussed, as well as the contribution to the uncertainty originated from the measurement protocol.
IICCEESS
5
PD Definitions
1. Spatial-average power density flux crossing the surface
2. Spatial-average norm of Poynting vector on the surface
Non-physical overestimation
𝑆𝑛,𝑎𝑣𝑔(𝒓) =1
2𝐴𝑎𝑣
𝐴𝑎𝑣
𝑅𝑒 𝑬 × 𝑯∗ ∙ 𝒏𝑑𝐴
𝑆𝑡𝑜𝑡,𝑎𝑣𝑔(𝒓) =1
2𝐴𝑎𝑣
𝐴𝑎𝑣
| 𝑅𝑒 𝑬 × 𝑯∗ |𝑑𝐴
Which definitions are better correlate with temperature elevation in the tissue ?
IICCEESS
6
Ad-Hoc Groups
AHG Modeling
9 Participants
AHG Measurement
2 Participants
AHG Thermographic Measurement
2 Participants
IICCEESS
7
AHG Modeling
Radiating Sources
Antenna Type Frequencies
(GHz)
Exposure
Evaluation
Distance
(mm)
CAD Files
Provided
Dipole 10, 30, 60 , 90 2, 5, 10, 50 ,150 No
Patch 10, 30, 60 , 90 2, 5, 10, 50 ,150 No
Patch Array 10, 30, 60 , 90 2, 5, 10, 50 ,150 No
Dipole Array 10, 30, 60 , 90 2, 5, 10, 50 ,150 Yes
Slotted Array 10, 30, 60 , 90 2, 5, 10, 50 ,150 Yes
Computational Method and Human Model
- density: 1100 kg/m3- heat capacity: 3400 (J/kg/K)- thermal conductivity: 0.37 (W/m/K)- perfusion: 30 (ml/min/kg)- convection coefficient of 8
IICCEESS
8
AHG Modeling – Results Metrics
Heating Factors
IICCEESS
9
AHG Modeling – Statistical Analysis
Correlation Coefficient
All Data 𝒓𝒏𝟏 𝒓𝒕𝒐𝒕𝟏 𝒓𝒏𝟒 𝒓𝒕𝒐𝒕𝟒
Whole set 0,788 0,819 0,709 0,794
𝒅 ≥ 𝟓 𝒎𝒎 0,858 0,854 0,766 0,774
σ
(HFn avg. 1) σ
(HFtot avg. 1) σ
(HFn avg. 4) σ
(HFtot avg. 4) σ
(HFn avg. 1 & 4) σ
(HFtot avg. 1 & 4)
NICT 0,01107 0,00696 0,02732 0,01591 0,02306 0,01375
NITech 0,00504 0,00455 0,01949 0,01576 0,01520 0,01219
SCAU 0,00481 0,00442 0,01946 0,01603 0,01532 0,01255
3DS 0,00544 0,00501 0,01059 0,00570 0,00872 0,00551
IT'IS 0,00493 0,00422 0,02047 0,00909 0,01625 0,00791
UniSplit 0,00820 0,00501 0,02882 0,01344 0,02253 0,01092
All 0,00661 0,00503 0,01995 0,01301 0,01575 0,01041
Heating Factor Std Deviation
Definition with Norm of PD seems to correlate better
with temperature elevation
IICCEESS
10
AHG Measurement
Measurement Structure and Results
Dipole Array 10, 30, 60 , 90 2, 5, 10, 50 ,150
Slotted Array 10, 30, 60 , 90 2, 5, 10, 50 ,150
WiGig Mockup 58.32, 60.48, 62.64 2, 5, 10, 50
Dipole Array 10, 30, 60 , 90 2, 5, 10, 50 ,150
Slotted Array 10, 30, 60 , 90 2, 5, 10, 50 ,150
WiGig Mockup 58.32, 60.48, 62.64 2, 5, 10, 50
Distance
(mm)Antenna Type
Frequencies
(GHz)
IICCEESS
11
AHG Thermographic Measurement
Exposure scenario 1 Exposure scenario 2
Square averaging area [cm2]
1 4 1 4
p-sPDn [W/m2] 0.90 0.70 0.79 0.62
p-sPDtot [W/m2] 0.90 0.70 0.90 0.72
HFn [oC/(W/m2)] 0.011 0.014 0.010 0.013
HFtot [oC/(W/m2)] 0.011 0.014 0.0088 0.011
IICCEESS
12
Next Steps and expected Output
Technical report to be published as IEEE Guide
General Paper
Further studies ?
IICCEESS
13
Participants Member, Name e-mail
1 Yinliang Diao [email protected]
2 Kensuke [email protected]
3 Kun Li [email protected]
4 Kai Niskala [email protected]
5 Kenneth Foster [email protected]
6 Pan, Yi (IC) [email protected]
7Greguy Saint-
Pierre [email protected]
8 JC Chen [email protected]
9 Niels Kuster [email protected]
10 Mark Douglas [email protected]
11Valerio De
Santis [email protected]
12 Quirino Balzano [email protected]
13Alexander.PROK
14 Ae-Kyoung [email protected]
15 Yao Zhen [email protected]
16 John Roman [email protected]
17 Andreas Christ [email protected]
18 Akimasa Hirata [email protected]
19 Teruo Onishi [email protected]
20 Davide Colombi [email protected]
21 Goga [email protected]
22 Dragan Poljak [email protected]
IEEE/ICES TC95
Task Force 2
Uncertainty of low-frequency
dosimetry in segmented models
Co-chairs:
Yinliang Diao (South China Agri. Univ., China)
Essam Rashed (BUE, Egypt)
ICES 2018
Chandler, USA
January 24, 2018
Slide 2
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
TF2 created in August 23rd, 2019.
(SC6 EMF Dosimetry Modeling)
Co-Chair: Yinliang Diao (South China Agri. Univ., China)
Co-Chair: Essam Rashed (BUE, Egypt)
SCOPE: Resolve uncertainties related to numerical models
that calculate electric fields induced within the body by external
electromagnetic fields or contact currents, as well as thresholds
of human response to the spatial and temporal characteristics of
the induced fields and temperature.
ICES 2018
Chandler, USA
January 24, 2018
Slide 3
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Within the general scope, we consider unresolved issues raised in
the research agenda of the IEEE ICES (Reilly and Hirata 2016)
ICES 2018
Chandler, USA
January 24, 2018
Slide 4
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Research agenda of the IEEE ICES (Reilly and Hirata
2016) 2.2. Modeling of skin, muscle, and CNS tissue
Skin-to-skin contact
Accurate modeling of the skin thickness
2.3. Numerical artifacts Stair-case artifacts
2.4. Spatial averaging 2 mm cube vs. 5 mm line
ICES 2018
Chandler, USA
January 24, 2018
Slide 5
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
On-going TF2 Activities
1. Skin-to-skin contact
Measurement experiments (Mag. Stimulator)
Computational models (TARO, XCAT)
A question arises if potential enhancement of computed electric
field, which may be attributable to a limitation of skin modeling,
is related to the electrostimulation.
ICES 2018
Chandler, USA
January 24, 2018
Slide 6
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Measurements for stimulus threshold
abd
uct
ion
add
uct
ion
Clo
se l
oo
pO
pen
lo
op
Experiment #1 Experiment #2
TMS (figure-8 coil), 8 subjects, 3x2 (ascending/decending) MSO trials
ICES 2018
Chandler, USA
January 24, 2018
Slide 7
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Measurements for stimulus threshold
ICES 2018
Chandler, USA
January 24, 2018
Slide 8
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Skin Fat Muscle Tendon Bone
(cortical)
Bone
(marrow)
Blood
vessels
Hand models
TARO
XCAT
(Nagaoka, PMB, 2004)
(Segars, Med. Phys., 2010)
ICES 2018
Chandler, USA
January 24, 2018
Slide 9
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Customization
1. Kinematic joint labeling
2. Extract skeleton
3. Customize position
4. Bone registration
5. Remaining tissues registration
ICES 2018
Chandler, USA
January 24, 2018
Slide 10
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
p1
p2
p3q3
q2
q1
o
t1
t2
t3
𝛼
Customization
ICES 2018
Chandler, USA
January 24, 2018
Slide 11
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Customization
TARO XCAT
Close loop Open loopClose loop Open loop
ICES 2018
Chandler, USA
January 24, 2018
Slide 12
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
4.0
0.0
EF
[mV/m]
EF distribution
TARO (adduction/abduction)
Avg. %ileAbduction [mV/m] Adduction [mV/m]
All tissues skin others All tissues skin others
2 m
m3 100 3.460 3.460 2.850 38.730 38.730 17.140
99.9 2.140 2.780 1.310 15.090 23.750 2.640
99 1.190 1.990 0.990 3.340 13.930 1.060
5 m
m
100 2.970 2.970 2.200 21.740 21.740 19.290
99.9 1.940 2.360 1.250 13.870 16.420 9.910
99 1.230 1.550 0.940 6.140 10.460 2.560
SPFD & multigrid method
ICES 2018
Chandler, USA
January 24, 2018
Slide 13
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
2.0
0.0
EF
[mV/m]
EF distribution
XCAT (adduction/abduction)
Avg. %ileAbduction [mV/m] Adduction [mV/m]
All tissues skin others All tissues skin others
2 m
m3 100 4.560 4.560 2.340 21.210 21.210 10.110
99.9 1.640 3.640 1.520 15.640 19.700 3.070
99 1.140 2.020 1.120 3.140 17.430 1.240
5 m
m
100 3.090 3.100 2.000 10.390 10.390 9.030
99.9 1.810 2.370 1.540 8.980 9.840 7.000
99 1.230 1.650 1.110 5.590 8.560 2.660
ICES 2018
Chandler, USA
January 24, 2018
Slide 14
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
10.0
0.0
EF
[mV/m]
EF distribution
TARO (open/close loop)Avg. %ile
Open loop [mV/m] Close loop [mV/m]
All tissues skin others All tissues skin others
2 m
m3 100 3.780 2.250 3.780 63.370 63.370 58.620
99.9 1.300 2.050 1.300 1.030 1.540 1.020
99 0.700 1.370 0.700 0.610 1.120 0.610
5 m
m
100 5.080 5.080 4.660 72.990 72.990 69.320
99.9 1.430 2.070 1.300 1.830 5.610 1.630
99 0.760 1.260 0.700 0.920 1.470 0.860
ICES 2018
Chandler, USA
January 24, 2018
Slide 15
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
10.0
0.0
EF
[mV/m]
EF distribution
XCAT (open/close loop)Avg. %ile
Open loop [mV/m] Close loop [mV/m]
All tissues skin others All tissues skin others
2 m
m3 100 6.040 6.040 3.720 52.950 52.950 19.420
99.9 2.270 4.050 2.120 2.370 28.220 2.170
99 0.990 2.540 0.940 1.010 3.030 0.950
5 m
m
100 4.970 4.970 3.610 24.950 24.900 24.950
99.9 2.660 3.730 2.110 3.380 14.020 2.370
99 1.160 2.200 0.930 1.240 2.660 0.960
ICES 2018
Chandler, USA
January 24, 2018
Slide 16
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Conclusion TMS measurements for hand electrostimultion
threshold No significant difference for skin-to-skin
contact scenarios.
Computational models (TARO / XCAT) of 0.5 mm
High EF values at skin-to-skin regions.
Considering the complicated (inhomogeneous)
anatomy of skin high EF computed at skin-to-skin
regions is likely due to poor modeling and limited
resolution of anatomical models.
ICES 2018
Chandler, USA
January 24, 2018
Slide 17
IEEE ICES
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Thank you
IEEE/ICES TC95
Task Force 2
Uncertainty of low-frequency
dosimetry in segmented models
Co-chairs:
Yinliang Diao (SCAU, China)
Essam Rashed (BUE, Egypt)
ICES 2020
Florida, USA
January 23, 2020
Slide 2
IEEE ICES
TF2 created in August 23rd, 2019.
(SC6 EMF Dosimetry Modeling)
Co-Chair: Yinliang Diao (South China Agri. Univ., China)
Co-Chair: Essam Rashed (BUE, Egypt)
SCOPE: Resolve uncertainties related to numerical models
that calculate electric fields induced within the body by
external electromagnetic fields or contact currents, as well as
thresholds of human response to the spatial and temporal
characteristics of the induced fields and temperature.
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Slide 3
IEEE ICES
Within the general scope, WG4
considers unresolved issues raised
in the research agenda of the IEEE
ICES (Reilly and Hirata 2016)
TF2: Uncertainty of LF dosimetry in segmented models
2.4 Spatial averaging
“Questions arise as to the propriety of averaging over a region that straddles the
boundary between two different tissues having disparate conductivities, such as
seen in the layers of skin.”
“It would also be useful to investigate the validity of LF spatial averaging
methods of the external applied field to derive a single field value for comparison
with IEEE’s maximum permissible exposures (MPEs) or ICNIRP’s reference
levels (RLs)...”
ICES 2020
Florida, USA
January 23, 2020
Slide 4
IEEE ICES
On-going TF2 Activities
1. Spatial Averaging Schemes of In Situ Electric
Field for Low-Frequency Magnetic Field Exposures IEEE specifies spatial averaging along a 5-mm line
ICNIRP specifies spatial averaging within a contiguous tissue
volume of 2 × 2 × 2 mm3
Aims: Compare the in situ electric field in the post-processing
algorithm prescribed in the international guidelines/standard.
Main emphasis:
the implementation of averaging schemes
cases in which the prescribed averaging dimensions cross a
tissue/tissue or a tissue/air interface.
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Slide 5
IEEE ICES
Models:
multi-layer sphere
skin (76-80 mm), fat (74-76 mm), muscle (72-74 mm), skull
(68-72 mm), cerebrospinal fluid (66-68 mm), and grey matter
(0-66 mm); res=0.5, 1, 2 mm
Anatomical human model TARO
res=0.5, 1, 2 mm
Exposure scenarios
Magnetic flux density: 0.1mT (uniform)
Frequency: 50Hz
Direction: anterior-posterior (AP) direction
TF2: Uncertainty of LF dosimetry in segmented models
x(LAT)
y(AP)
z(TOP)
ICES 2020
Florida, USA
January 23, 2020
Slide 6
IEEE ICES
Method
Scalar-potential finite-difference method
The scalar potential were solved iteratively using geometric
multigrid methods in NiTech.
Post-processing
Averaged over 2-mm cube
Averaged over 5-mm line segment
Percentile values
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Slide 7
IEEE ICES
Implementations of Spatial Averaging
2-mm cubic averaging
𝐸𝑉(𝒓𝑐) is arithmetic average of vector E field in a 2-mm cube
𝑉1 is target continuous tissue inside the cube
𝑝 is a factor represents the percentage of air/other tissue inside the
cube: 𝑝 = 100 × (𝑉 − 𝑉1)/𝑉
𝑝𝑚𝑎𝑥 is the max permissible percentage of air/other tissue
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Slide 8
IEEE ICES
Implementations of Spatial Averaging
5-mm linear averaging
Average E field along a line in (𝜃, 𝜙)
𝜃, 𝜙 vary from 0° to 180° in 20° intervals
The final 𝐸𝐿 𝒓𝑐 is taken as the max over 81 directions
𝐿1 is the length of the segment inside the same tissue
𝑝 is a factor represents the percentage of air/other tissue inside the
line: 𝑝 = 100 × (𝐿 − 𝐿1)/𝐿
𝑝𝑚𝑎𝑥 is the max permissible percentage of air/other tissue
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Slide 9
IEEE ICES
Multi-layer sphere
TF2: Uncertainty of LF dosimetry in segmented models
Skin Grey matter
Taro model
ICES 2020
Florida, USA
January 23, 2020
Slide 11
IEEE ICES
Electric field distributions in Taro model
1mm2mm 0.5mm
Voxel field distributions Volume-averaged Line-averaged
1mm 0.5mm 1mm 0.5mm
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Slide 12
IEEE ICES
Relative differences between volume- and line- averaging
Tissue Percentile Multi-layer sphere Taro model
Pmax=0% Pmax=20% Pmax=40% Pmax=0% Pmax=20% Pmax=40%
All
tissues
Max 1.4 0.5 0.6 21.9 15.9 4.8
99.99 0.9 0.0 0.2 8.2 9.0 6.1
99.9 0.3 0.1 0.1 3.3 10.1 7.8
99 0.6 0.9 0.9 0.7 4.1 3.2
Grey
Matter
Max 0.0 2.3 1.6 29.0 30.5 14.5
99.99 1.3 1.6 0.0 5.6 10.8 5.2
99.9 0.7 1.2 1.6 3.7 7.2 2.8
99 0.4 0.7 1.2 5.9 4.2 1.3
ref
100V L
r
E Ed
E
-= エ
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Slide 13
IEEE ICES
Air/other tissue inclusion in averaging, multi-layer sphere
TF2: Uncertainty of LF dosimetry in segmented modelsV
olu
me
ave
rag
eL
ine
ave
rag
e
ICES 2020
Florida, USA
January 23, 2020
Slide 14
IEEE ICES
Air/other tissue inclusion in averaging, Taro model
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Slide 15
IEEE ICES
Inclusion of subcutaneous tissue in volume-averaging for skin
TARO (res=1 mm)
TF2: Uncertainty of LF dosimetry in segmented models
TARO (res=0.5 mm)
𝑝: percentage of air/other
tissue inside the cube
𝑝: percentage of air
tissue inside the cube
ICES 2020
Florida, USA
January 23, 2020
Slide 16
IEEE ICES
Conclusions Percentile in situ electric fields are not radically different
between the volume- and line-averaging schemes.
Restricting the averaging volumes or linear segments
completely within a tissue will often lead to exclusion of voxels
located at the tissue boundaries. Inclusion of a percentage of
air/other tissues may be a practical compromise.
For cubic averaging in skin, a large variation of in situ electric
fields occurs if no air/other tissues are allowed in the averaging
volume. ~10% air inclusion is suggested for reproducibly
averaged electric fields with different voxel resolutions.
TF2: Uncertainty of LF dosimetry in segmented models
ICES 2020
Florida, USA
January 23, 2020
Slide 17
IEEE ICES
Thank you
TF2: Uncertainty of LF dosimetry in segmented models