Computer modeling of laser induced injury of the skin

Jean, Mathieu; Schulmeister, Karl; Stuck, Bruce E.

doi:10.2351/1.5056815

Cited by 5 publications

(5 citation statements)

References 21 publications

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“…In the discussion below, thermal damage data will be compared to thermal damage models for skin, cornea, and retina developed by Jean et al (2013, 2021) and Jean and Schulmeister (2017). These studies were done to inform development of ICNIRP exposure limits for pulsed infrared (IR) radiation (ICNIRP 2013a and b), in part to address potentially serious hazards from pulsed IR lasers.…”

Section: Reference Modelsmentioning

confidence: 99%

“…Jean et al (2013) fitted 93 sets of thermal damage data measured in vivo from pulsed IR energy to pig and human skin over a wide variety of exposure parameters and wavelengths. The exposure durations ranged from 350 μs to 70 s and wavelengths from 500 nm to 10.6 μm.…”

Section: Reference Modelsmentioning

confidence: 99%

“…Only scant thermal damage data are available from RF exposures to tissue in the considered frequency range. However, a wealth of other thermal damage data is available from tissue damage studies involving exposure to infrared energy [summarized in models by Jean et al (2013, 2021), Jean and Schulmeister (2017)] as well as from other thermal damage studies.…”

Section: Experimental Thermal Pain and Burn Thresholdsmentioning

confidence: 99%

“…For short term exposures, the data are quite extensive. Jean et al (2013, 2021), Jean and Schulmeister (2017) summarized an immense amount of thermal damage data for ocular tissues and skin, from carefully done studies by multiple investigators that were meticulously analyzed. Most of those data derive from laser hazard studies, involve exposure to brief and high intensity pulses of infrared energy, and provide a good understanding of temperature-time relations for thermal damage for short term exposures.…”

Section: Comments On Adequacy Of the Datamentioning

confidence: 99%

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Time-temperature Thresholds and Safety Factors for Thermal Hazards from Radiofrequency Energy above 6 GHz

2021

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Two major sets of exposure limits for radiofrequency (RF) radiation, those of the International Commission on Nonionizing Radiation Protection (ICNIRP 2020) and the Institute of Electrical and Electronics Engineers (IEEE C95.1–2019), have recently been revised and updated with significant changes in limits above 6 GHz through the millimeter wave (mm-wave) band (30–300 GHz). This review compares available data on thermal damage and pain from exposure to RF energy above 6 GHz with corresponding data from infrared energy and other heat sources and estimates safety factors that are incorporated in the IEEE and ICNIRP RF exposure limits. The benchmarks for damage are the same as used in ICNIRP IR limits: minimal epithelial damage to cornea and first-degree burn (erythema in skin observable within 48 h after exposure). The data suggest that limiting thermal hazard to skin is cutaneous pain for exposure durations less than ≈20 min and thermal damage for longer exposures. Limitations on available data and thermal models are noted. However, data on RF and IR thermal damage and pain thresholds show that exposures far above current ICNIRP and IEEE limits would be required to produce thermally hazardous effects. This review focuses exclusively on thermal hazards from RF exposures above 6 GHz to skin and the cornea, which are the most exposed tissues in the considered frequency range.

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Section: Reference Modelsmentioning

confidence: 99%

Section: Reference Modelsmentioning

confidence: 99%

Section: Experimental Thermal Pain and Burn Thresholdsmentioning

confidence: 99%

Section: Comments On Adequacy Of the Datamentioning

confidence: 99%

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Time-temperature Thresholds and Safety Factors for Thermal Hazards from Radiofrequency Energy above 6 GHz

2021

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“…where z is the coordinate axis normal to the skin (positive direction into skin), h is a convective heat exchange coefficient, and A is an empirical parameter that models cooling by evaporation of skin moisture. Values for h from the literature vary widely, from 1-15 W/(m 2 o C), while Jean et al [23] use 2 W/(m o C 2 ) for A. A finite element solution of Eq.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

Transient Thermal Responses of Skin to Pulsed Millimeter Waves

et al. 2020

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This study examines thermal responses of skin to pulsed millimeter wave (mm-wave) radiofrequency (RF) radiation. We review limits for pulse fluence in the IEEE Std. C95.1-2019 and the 2020 guideline of the International Commission on Nonionizing Radiation Protection (ICNIRP), as well as the recently reaffirmed guidelines of the U.S. Federal Communications Commission (FCC). The study employs a simple one-dimensional thermal model for skin and Pennes' bioheat equation (BHTE). The predicted temperature increases produced by 3-sec pulses at 94 GHz agree well with previous experimental results with no adjustable parameters in the model, and the anticipated threshold of cutaneous thermal pain and burns are consistent with the scant available data for pulsed mm-waves, as well as a larger body of data on thermal hazards from pulsed infrared radiation. The model suggests that the implicit limits on pulse fluence in present FCC guidelines might allow, in extreme (and, in practice, unrealistic) cases, transient increases in skin temperature that can approach thresholds for thermal pain but well below those anticipated to cause thermal damage. Limits on pulse fluence in the current IEEE and ICNIRP exposure guidelines would preclude such effects. For realistic exposures from wireless and other technologies that transmit pulsed RF energy that comply with time-averaged exposure limits, the pulse fluence is far too low to produce hazardous thermal transients in skin. A thermal analysis of FCC's proposed "device-based time averaging" shows that the resulting limits on device emissions will result in thermal transients in skin that are roughly an order of magnitude below much slower increases in temperature due to time-averaged exposure. An appendix discusses the applicability of two approximations to the bioheat equation that can be used to estimate temperature increases in skin from exposure to mm-waves.

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An ultrasonography‐based approach for tissue modelling to inform photo‐therapy treatment strategies

Kallepalli

Halls

James

et al. 2022

Journal of Biophotonics

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Currently, diagnostic medicine uses a multitude of tools ranging from ionising radiation to histology analysis. With advances in piezoelectric crystal technology, high-frequency ultrasound imaging has developed to achieve comparatively high resolution without the drawbacks of ionising radiation. This research proposes a low-cost, non-invasive and real-time protocol for informing photo-therapy procedures using ultrasound imaging.We combine currently available ultrasound procedures with Monte Carlo methods for assessing light transport and photo-energy deposition in the tissue. The measurements from high-resolution ultrasound scans are used as input for optical simulations. Consequently, this provides a pipeline that will inform medical practitioners for better therapy strategy planning. While validating known inferences of light transport through biological tissue, our results highlight the range of information such as temporal monitoring and energy deposition at varying depths. This process also retains the flexibility of testing various wavelengths for individual-specific geometries and anatomy.

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Computer modeling of laser induced injury of the skin

Cited by 5 publications

References 21 publications

Time-temperature Thresholds and Safety Factors for Thermal Hazards from Radiofrequency Energy above 6 GHz

Time-temperature Thresholds and Safety Factors for Thermal Hazards from Radiofrequency Energy above 6 GHz

Transient Thermal Responses of Skin to Pulsed Millimeter Waves

An ultrasonography‐based approach for tissue modelling to inform photo‐therapy treatment strategies

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