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Huang J, Jia M, Li Y, Yan M, Wang K, Li X. Finite element simulation and experimental validation of thermal damage to isolated porcine skin tissue by femtosecond laser welding. JOURNAL OF BIOPHOTONICS 2024:e202400224. [PMID: 39049557 DOI: 10.1002/jbio.202400224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 06/12/2024] [Accepted: 07/05/2024] [Indexed: 07/27/2024]
Abstract
The welding effect of the laser on skin tissue is reduced by thermal damage to skin tissue, and greater thermal damage to skin tissue caused by the laser is prevented by predicting thermal damage. In this paper, a finite element model is established for the temperature field of skin tissue scanned by a femtosecond laser to obtain the influence of laser process parameters and scanning path on the thermal damage parameters of skin tissue and the thermal damage area, and verified experimentally. The results show that the established finite element model is accurate and can accurately reflect the temperature distribution during the process of femtosecond laser welding of porcine skin tissues; used to predict the thermal damage parameters of the skin tissues and the thermal damage area; and provide guidance for the study of the femtosecond laser welding of the skin tissues process to obtain the optimal process parameters.
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Affiliation(s)
- Jun Huang
- School of Material Science and Technology, Nanjing University of Science and Technology, Nanjing, China
| | - Mengshi Jia
- School of Material Science and Technology, Nanjing University of Science and Technology, Nanjing, China
| | - Yanyu Li
- School of Material Science and Technology, Nanjing University of Science and Technology, Nanjing, China
| | - Mintao Yan
- School of Material Science and Technology, Nanjing University of Science and Technology, Nanjing, China
| | - Kehong Wang
- School of Material Science and Technology, Nanjing University of Science and Technology, Nanjing, China
| | - Xiaopeng Li
- School of Material Science and Technology, Nanjing University of Science and Technology, Nanjing, China
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2
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Sander MY, Zhu X. Infrared neuromodulation-a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:066701. [PMID: 38701769 DOI: 10.1088/1361-6633/ad4729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 05/03/2024] [Indexed: 05/05/2024]
Abstract
Infrared (IR) neuromodulation (INM) is an emerging light-based neuromodulation approach that can reversibly control neuronal and muscular activities through the transient and localized deposition of pulsed IR light without requiring any chemical or genetic pre-treatment of the target cells. Though the efficacy and short-term safety of INM have been widely demonstrated in both peripheral and central nervous systems, the investigations of the detailed cellular and biological processes and the underlying biophysical mechanisms are still ongoing. In this review, we discuss the current research progress in the INM field with a focus on the more recently discovered IR nerve inhibition. Major biophysical mechanisms associated with IR nerve stimulation are summarized. As the INM effects are primarily attributed to the spatiotemporal thermal transients induced by water and tissue absorption of pulsed IR light, temperature monitoring techniques and simulation models adopted in INM studies are discussed. Potential translational applications, current limitations, and challenges of the field are elucidated to provide guidance for future INM research and advancement.
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Affiliation(s)
- Michelle Y Sander
- Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, MA 02215, United States of America
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215, United States of America
- Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, MA 02446, United States of America
- Photonics Center, Boston University, 8 Saint Mary's Street, Boston, MA 02215, United States of America
- Neurophotonics Center, Boston University, 24 Cummington Mall, Boston, MA 02215, United States of America
| | - Xuedong Zhu
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215, United States of America
- Photonics Center, Boston University, 8 Saint Mary's Street, Boston, MA 02215, United States of America
- Neurophotonics Center, Boston University, 24 Cummington Mall, Boston, MA 02215, United States of America
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Jean M, Schulmeister K. Laser-induced injury of the skin: validation of a computer model to predict thresholds. BIOMEDICAL OPTICS EXPRESS 2021; 12:2586-2603. [PMID: 34123490 PMCID: PMC8176813 DOI: 10.1364/boe.422618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/25/2021] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
The exposure and emission limits of ICNIRP, IEC 60825-1 and ANSI Z136.1 to protect the skin are based on a limited number of in-vivo studies. To broaden the database, a computer model was developed to predict injury thresholds in the wavelength range from 400 nm to 20 µm and was validated by comparison with all applicable experimental threshold data (ED50) in the wavelength range from 488 nm to 10.6 µm and exposure durations between 8 µs and 630 s. The model predictions compare favorably with the in-vivo data with an average ratio of computer prediction to ED50 of 1.01 (standard deviation ± 46%) and a maximum deviation of 2.6. This computer model can be used to improve exposure limits or for a quantitative risk analysis of a given exposure of the skin.
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Affiliation(s)
- Mathieu Jean
- Seibersdorf Labor GmbH, Seibersdorf 2444, Austria
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Jiao L, Wang C, Zhang K, Wang J, Yang Z. Porcine skin damage threshold from mid-infrared optical parametric oscillator radiation at 3.743 µm. BIOMEDICAL OPTICS EXPRESS 2020; 11:7165-7174. [PMID: 33408987 PMCID: PMC7747919 DOI: 10.1364/boe.409387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 11/09/2020] [Accepted: 11/11/2020] [Indexed: 06/12/2023]
Abstract
There is increasing use of mid-infrared optical parametric oscillator radiation operating in the wavelength range of 3-5 µm. To expand existing damage data for skin exposure to lasers in this wavelength region, the in-vivo damage threshold at the wavelength of 3.743 µm was determined in a Guizhou miniature pig model for an exposure duration of 1.0 s. The irradiance of the laser spot was nearly Gaussian-distributed and the 1/e2 beam diameter on the animal skin surface was fixed at 0.94 and 0.88 cm along horizontal and vertical directions. Damage lesion determinations were performed at 1- and 24-hour post-exposure. The probit analysis was employed to establish the ED50 values. The ED50 expressed in peak radiant exposure for the Gaussian spot was 4.04 J/cm2 at the 24-hour post-exposure. Sufficient margin existed between the damage threshold and MPE from the current laser safety standard. The obtained data may contribute to the knowledge base for refinement of laser safety standard in the wavelength range of 2.6-1000 µm.
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Affiliation(s)
- Luguang Jiao
- Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Chao Wang
- Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Kaizeng Zhang
- Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Jiarui Wang
- Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Zaifu Yang
- Beijing Institute of Radiation Medicine, Beijing 100850, China
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Ma Q, Fan Y, Luo Z, Cui Y, Kang H. Quantitative analysis of collagen and capillaries of 3.8-μm laser-induced cutaneous thermal injury and wound healing. Lasers Med Sci 2020; 36:1469-1477. [PMID: 33185748 DOI: 10.1007/s10103-020-03193-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/09/2020] [Indexed: 11/26/2022]
Abstract
The biological effects of cutaneous thermal injury and wound healing after 3.8-μm laser radiation were investigated by observing the effects of different radiation doses on in vivo cutaneous tissue. A 3.8-μm laser with a radiation dose that changes from small (5.07) to large (15.74 J/cm2) was used to irradiate mouse skin with the 2 × 4 grid array method. The healing progress of laser-injured spots, pathological morphology (H&E staining), and collagen structure changes (Sirius Red staining) were dynamically observed from one hour to 21 days after laser radiation, and the capillary count and collagen content were quantitatively and comparatively analyzed. When the radiation doses were 5.07, 6.77, 8.21, and 9.42 J/cm2, a white coagulation spot predominantly occurred, and when the radiation doses were 11.09 12.23, 14.13, 15.74 J/cm2, a small injured spot predominantly occurred. One hour after radiation, the collagen structure was obviously damaged. Three to fourteen days after radiation, the hyperplasia and morphology of the collagen in the 5.07 J/cm2 group were significantly better than those in the other dose groups. The number of capillaries in the 5.07 J/cm2 and 6.77 J/cm2 groups was significantly higher than that in the normal group (P < 0.01 or P < 0.05). Twenty-one days after radiation, only the collagen in the 5.07 J/cm2 group was densely arranged, and it was basically close to the normal group level. The collagen content in the 5.07 J/cm2 group was approximately 10.7%, but it was still lower than that in the normal group (with a collagen content of approximately 14.1%). The collagen in the other dose groups was diminished and had not returned to the normal group level. As the dose of the 3.8-μm laser increased, skin thermal injury gradually increased, the full-thickness skin increased, and the collagen content decreased, showing better dose-dependent and time-dependent effect relationships. The increase in capillaries in the early stage of laser radiation and the significant increase in collagen content in the middle and late stages of laser radiation were two important factors that promoted wound healing.
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Affiliation(s)
- Qiong Ma
- Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Yingwei Fan
- Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Zhenkun Luo
- Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Yufang Cui
- Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Hongxiang Kang
- Beijing Institute of Radiation Medicine, Beijing, 100850, China.
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Tulsawani R, Sharma P, Sethy NK, Kumari P, Ganju L, Prakash S, Chouhan S. Acute exposure of 532 nm laser differentially regulates skin tissue transcription factors. PLoS One 2020; 15:e0230175. [PMID: 32191734 PMCID: PMC7082019 DOI: 10.1371/journal.pone.0230175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 02/24/2020] [Indexed: 12/16/2022] Open
Abstract
High energy laser, particularly 532 nm, is widely used in defense and medical applications and there is need to address its occupational safety. Thermal and non-thermal effects of 532 nm high energy laser on skin are cause of concern. This study indicates impact of 532 nm laser on rat skin and first of its kind of attempt to understand transcriptional activation of genes as an early response following laser exposure. Skin of experimental rats were exposed to 532 nm radiance at 0.1, 0.25 and 0.50 W/cm2 for 10 sec. Thermographic changes of skin exposed to 532 nm laser exhibited increased Tmax temperature in radiance dependent manner. After thermal imaging, skin of experimental rats was collected 1 h post laser exposure for studying differential gene expression. The skin exposed to lower power density (0.1 W/cm2) did not show significant changes in expression of gene pathways studied. At moderate radiance (0.25 W/cm2), predominantly canonical wnt/B-catenin pathway genes notch1, axin2, ccdn1, wnt5a and redox homeostasis genes; txn1, nqo1 and txnrd1 were expressed. At higher radiance (0.5 W/cm2), significant repression of genes related to wound healing process particularly notch/wnt pathway viz. hes5, wnt1, wn3b with higher expression of dab2 was recorded. The data obtained from these studies would help in drawing safety limits for skin exposure to 532 nm laser. Further, genes expressed at moderate and high level of radiance exposure to skin were distinct and differential and provide new avenue to configure pathway to counteract laser induced delay in tissue injury and hair follicular damage.
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Affiliation(s)
| | - Purva Sharma
- Defence Institute of Physiology and Allied Sciences, Delhi, India
| | | | - Pooja Kumari
- Defence Institute of Physiology and Allied Sciences, Delhi, India
| | - Lilly Ganju
- Defence Institute of Physiology and Allied Sciences, Delhi, India
| | - Satya Prakash
- Laser Science and Technology Centre, Metcalfe House, Delhi, India
| | - Satish Chouhan
- Defence Institute of Physiology and Allied Sciences, Delhi, India
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7
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Jiao L, Wang J, Fan Y, Yang Z. Porcine skin damage thresholds and histological damage characteristics from 1319-nm laser radiation. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-9. [PMID: 31552723 PMCID: PMC6997579 DOI: 10.1117/1.jbo.24.9.095003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 09/06/2019] [Indexed: 06/10/2023]
Abstract
There is an increasing use of near-infrared lasers in biomedical applications operating in the spectrum between 1300 and 1400 nm. To corroborate and expand the existing safety data for skin exposure to lasers in this wavelength region, the in-vivo ED50 damage thresholds were determined in Guizhou miniature pigs for 1319-nm laser radiation. Exposure durations of 0.4, 1.0, and 3.0 s and 1 / e2 beam diameters of 0.98 and 1.96 cm were employed. Damage lesion determinations were performed at 1- and 24 h post exposure. The Bliss probit analysis was employed to establish the ED50 damage thresholds. Histopathological studies of skin damage were performed at 48 h after irradiation to reveal the damage characteristics. The skin damage thresholds at 1 h post exposure, given in peak radiant exposure, were 35.5, 36.1, and 37.1 J / cm2 at exposure durations of 0.4, 1.0, and 3.0 s with the spot diameter of 0.98 cm, and 28.6 J / cm2 at exposure duration of 3.0 s with the spot diameter of 1.96 cm. At 24 h post exposure, the ED50s increased slightly. Histologically, the thermal damage characteristics at the near-threshold level included gathering of the nuclear chromatin and cell vacuolation in the epidermis and deposition of blood cells in the capillary vessels. However, at the apparently above-threshold level, the damage characteristics included obvious stretching of the nuclear chromatin in the epidermis, closing of the capillary lumen, structural change of collagen fibers, and coagulative necrosis of the hair follicle cells. The damage induced by this laser could go deep into the fatty tissue. The obtained results may contribute to the knowledge base for the damage mechanisms and expand the database for the refinement of laser safety standards in the wavelength range of 1300 to 1400 nm.
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Affiliation(s)
- Luguang Jiao
- Beijing Institute of Radiation Medicine, Beijing, China
| | - Jiarui Wang
- Beijing Institute of Radiation Medicine, Beijing, China
| | - Yan Fan
- Beijing Institute of Radiation Medicine, Beijing, China
| | - Zaifu Yang
- Beijing Institute of Radiation Medicine, Beijing, China
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8
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Evers M, Ha L, Casper M, Welford D, Kositratna G, Birngruber R, Manstein D. Assessment of skin lesions produced by focused, tunable, mid-infrared chalcogenide laser radiation. Lasers Surg Med 2018; 50:961-972. [PMID: 29799127 DOI: 10.1002/lsm.22935] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2018] [Indexed: 02/01/2023]
Abstract
BACKGROUND Traditionally, fractional laser treatments are performed with focused laser sources operating at a fixed wavelength. Using a tunable laser in the mid-infrared wavelength range, wavelength-dependent absorption properties on the ablation process and thermal damage formation were assessed with the goal to obtain customizable tissue ablations to provide guidance in finding optimized laser exposure parameters for clinical applications. METHODS Laser tissue experiments were carried out on full thickness ex vivo human abdominal skin using a mid-infrared tunable chromium-doped zinc selenide/sulfide chalcogenide laser. The laser has two independent channels: a continuous wave (CW) output channel which covers a spectrum ranging from 2.4 μm to 3.0 μm with up to 9.2 W output power, and a pulsed output channel which ranges from 2.35 μm to 2.95 μm. The maximum pulse energy of the pulsed channel goes up to 2.8 mJ at 100 Hz to 1,000 Hz repetition rate with wavelength-dependent pulse durations of 4-7 ns. RESULTS Total ablation depth, ablation efficiency, and coagulation zone thickness were highly correlated to wavelength, pulse width, and pulse energy. Using the same total radiant exposure at 2.85 μm wavelength resulted in 10-times smaller coagulation zones and 5-times deeper ablation craters for one hundred 6 ns pulses compared to one 100 ms pulse. For a fixed pulse duration of 6 ns and a total radiant exposure of 2.25 kJ/cm2 the ablation depth increased with longer wavelengths. CONCLUSION The tunable laser system provides a useful research tool to investigate specific laser parameters such as wavelength on lesion shape, ablation depth and thermal tissue damage. It also allows for customization of the characteristics of laser lesions and therefore facilitates the selection of suitable laser parameters for optimized fractional laser treatments. Lasers Surg. Med. 50:961-972, 2018.© 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Michael Evers
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Institute for Biomedical Optics, University of Lübeck, Lübeck, 23562, Germany
| | - Linh Ha
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Institute for Biomedical Optics, University of Lübeck, Lübeck, 23562, Germany
| | - Malte Casper
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Institute for Biomedical Optics, University of Lübeck, Lübeck, 23562, Germany
| | - David Welford
- Endeavour Laser Technologies, Inc., Hathorne, Massachusetts 01937
| | - Garuna Kositratna
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Reginald Birngruber
- Institute for Biomedical Optics, University of Lübeck, Lübeck, 23562, Germany
| | - Dieter Manstein
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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Yang JC, Dong XX, Mu ZM, Jin WD, Huang H, Lu Y, Chen ZY, Li YX. Temporal and spatial temperature distributions on glabrous skin irradiated by a 1940 nm continuous-wave laser stimulator. BIOMEDICAL OPTICS EXPRESS 2015; 6:1451-63. [PMID: 25909027 PMCID: PMC4399682 DOI: 10.1364/boe.6.001451] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/14/2015] [Accepted: 02/23/2015] [Indexed: 06/04/2023]
Abstract
For predicting pain stimulation effects and avoiding damage in 1940nm laser evoked potentials (LEPs) experiments, a 2-layer finite element model (FEM-2) was constructed. A series of experiments were conducted on ex-vivo pig skin pieces to verify temperature distribution predicted by this model. Various laser powers and beam radii were employed. Experimental data of time-dependent temperature responses in different sub-skin depths and space-dependent surface temperature was recorded by thermocouple instrument. By comparing with the experimental data and model results, FEM-2 model was proved to predict temperature distributions accurately. A logarithmic relationship between laser power density and temperature increment was revealed by the results. It is concluded that power density is an effective parameter to estimate pain and damage effect. The obtained results also indicated that the proposed FEM-2 model can be extended to predict pain and damage thresholds of human skin samples and thus contribute to LEPs study.
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Affiliation(s)
- Ji-chun Yang
- Chinese Academy of Medical Science &Peking Union Medical College, Institute of Biomedical Engineering, Laboratory of Laser Medicine, No.236, Baidi Road, Tianjin, 300192,
China
| | - Xiao-xi Dong
- Chinese Academy of Medical Science &Peking Union Medical College, Institute of Biomedical Engineering, Laboratory of Laser Medicine, No.236, Baidi Road, Tianjin, 300192,
China
- Xiao-xi Dong and Ji-chun Yang contributed equally to this work
| | - Zhi-ming Mu
- Chinese Academy of Medical Science &Peking Union Medical College, Institute of Biomedical Engineering, Laboratory of Laser Medicine, No.236, Baidi Road, Tianjin, 300192,
China
| | - Wen-dong Jin
- Chinese Academy of Medical Science &Peking Union Medical College, Institute of Biomedical Engineering, Laboratory of Laser Medicine, No.236, Baidi Road, Tianjin, 300192,
China
| | - He Huang
- Chinese Academy of Medical Science &Peking Union Medical College, Institute of Biomedical Engineering, Laboratory of Laser Medicine, No.236, Baidi Road, Tianjin, 300192,
China
| | - Yu Lu
- Chinese Academy of Medical Science &Peking Union Medical College, Institute of Biomedical Engineering, Laboratory of Laser Medicine, No.236, Baidi Road, Tianjin, 300192,
China
- Tianjin University of Technology and Education, Electronic Engineering College, No.1310, Dagu South Road, Tianjin, 300222,
China
| | - Zhu-ying Chen
- Chinese Academy of Medical Science &Peking Union Medical College, Institute of Biomedical Engineering, Laboratory of Laser Medicine, No.236, Baidi Road, Tianjin, 300192,
China
| | - Ying-xin Li
- Chinese Academy of Medical Science &Peking Union Medical College, Institute of Biomedical Engineering, Laboratory of Laser Medicine, No.236, Baidi Road, Tianjin, 300192,
China
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Baac HW, Uribe-Patarroyo N, Bouma BE. High-energy pulsed Raman fiber laser for biological tissue coagulation. OPTICS EXPRESS 2014; 22:7113-23. [PMID: 24664059 PMCID: PMC4083053 DOI: 10.1364/oe.22.007113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We demonstrate a high-energy pulsed Raman fiber laser (RFL) with an emission wavelength of 1.44 μm, corresponding to an absorption peak of water. Microsecond pulses with >20 mJ/pulse and >40 W peak power were generated, well above the threshold for tissue coagulation and ablation. Here, we focus on the optical characterization and optimization of high-energy and high-power RFLs excited by an ytterbium fiber laser, comparing three configurations that use different Raman gain fibers, but all of which were prepared with a one-side opened, free-run mode without output mirrors. We show that the free-run configuration can generate sufficiently high energy without requiring a closed cavity design. Experimental RFL characteristics corresponded well with numerical simulations. We discuss the Stokes beam generation process in our system and loss mechanisms mainly associated with fiber Bragg gratings.
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Hibst R, Saal D, Russ D, Kunzi-Rapp K, Kienle A, Stock K. Thermal effects of white light illumination during microsurgery: clinical pilot study on the application safety of surgical microscopes. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:048003. [PMID: 20799846 DOI: 10.1117/1.3475953] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Modern operating microscopes offer high power illumination to ensure optimal visualization, but can also cause thermal damage. The aim of our study is to quantify the thermal effects in vivo and discuss conditions for safe use. In a pilot study on volunteers, we measured the temperature at the skin surface during microscope illumination, including the influence of anaesthesia and the effects of staining, draping, or moistening of the skin. Irradiation within the limit given by safety regulations (200 mW/cm(2)) results in skin surface temperature of 43 degrees C. Higher intensities (forearm 335 mW/cm(2), back 250 mW/cm(2)) are tolerated, resulting in reversible hyperaemia. At a very high illumination intensity (750 mW/cm(2)), pain occurs within 30 s at temperatures of 46 degrees C+/-1 degrees C (hand and forearm), and 43 degrees C+/-2 degrees C (back), respectively. Anaesthesia has no distinct effect on the temperature, whereas staining and drapes result in much higher temperatures (>100 degrees C). Moistening at practicable flow rates can reduce temperature efficiently when combined with a light absorbing and water absorbent drape. In conclusion, surgeons must be aware that surgical microscope illumination without protective means can cause skin temperatures to rise much above pain threshold, which in our study serves as a (conservative) benchmark for potential damage.
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Affiliation(s)
- Raimund Hibst
- Universitat Ulm, Institut fur Lasertechnologien in der Medizin und Messtechnik an der Universitat Ulm, Ulm, Germany.
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12
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Schaaf D, Johnson T. Relationships of skin depths and temperatures when varying pulse repetition frequencies from 2.0-microm laser light incident on pig skin. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:045007. [PMID: 20799802 DOI: 10.1117/1.3477324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Human perception of 2.0-microm infrared laser irradiation has become significant in such disparate fields as law enforcement, neuroscience, and pain research. Several recent studies have found damage thresholds for single-pulse and continuous wave irradiations at this wavelength. However, the only publication using multiple-pulse irradiations was investigating the cornea rather than skin. Literature has claimed that the 2.0-microm light characteristic thermal diffusion time was as long as 300-ms. Irradiating the skin with 2.0-microm lasers to produce sensation should follow published recommendations to use pulses on the order of 10 to 100 ms, which approach the theoretical thermal diffusion time. Therefore, investigation of the heating of skin for a variety of laser pulse combinations was undertaken. Temperatures of ex vivo pig skin were measured at the surface and at three depths from pulse sequences of six different duty factors. Differences were found in temperature rise per unit exposure that did not follow a linear relation to duty factor. The differences can be explained by significant heat conduction during the pulses. Therefore, the common heat modeling assumption of thermal confinement during a pulse may need to be experimentally verified if the pulse approaches the theoretical thermal confinement time.
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Affiliation(s)
- David Schaaf
- Colorado State University, Department of Environmental and Radiological Health Sciences, Fort Collins, Colorado 80523, USA
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13
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Choi IS, Chae YS, Zemek A, Protsenko DE, Wong B. Viability of human septal cartilage after 1.45 microm diode laser irradiation. Lasers Surg Med 2009; 40:562-9. [PMID: 18798294 DOI: 10.1002/lsm.20663] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND AND OBJECTIVES Chondrocyte viability following laser irradiation and reshaping has not been established for human nasal septal cartilage. Knowledge of the relationship between thermal injury and laser dosimetry is needed in order to optimize septal laser cartilage reshaping. The objective of this study was to determine the depth and width of thermal injury in human septal cartilage following laser irradiation. STUDY DESIGN/MATERIALS AND METHODS Excess fresh nasal septal cartilage sections from rhinoplasty or septoplasty operations were irradiated using a 1.45 microm diode laser 1.25-3.6 W (2.8 mm spot diameter) with 1 second fixed exposure time, and then at exposure times of 1-4 seconds for a fixed power of 1.25 W. An infrared camera recorded surface temperature profiles during irradiation, and the temperature data were incorporated into a rate process model to numerically estimate thermal damage. Calcein AM and ethidium homodimer-1 fluorescent dyes combined with confocal laser microscopy (CLM) were used to measure thermal damage. RESULTS CLM demonstrated clear demarcation between dead and living cells following irradiation. The extent of non-viable chondrocyte distributions increased with power and exposure time. The maximum depths of injury were 1,012 and 1,372 microm after 3.6 W 1 second and 1.25 W 4 seconds irradiation respectively. The damage predictions made by the rate process model underestimated thermal injury when compared with CLM measurements. CONCLUSIONS The assay system identified regions of non-viable chondrocytes in human septal cartilage and defined how thermal injury varies with dosimetry when using a 1.45 microm diode laser.
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Affiliation(s)
- Ick-Soo Choi
- Department of Otolaryngology, Head and Neck Surgery, Seoul Paik Hospital, Inje University, 5 Mareunnae Gil, Jung Gu, Seoul 100032, Korea.
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14
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Chen B, Thomsen SL, Thomas RJ, Oliver J, Welch AJ. Histological and modeling study of skin thermal injury to 2.0 μm laser irradiation. Lasers Surg Med 2008; 40:358-70. [DOI: 10.1002/lsm.20630] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Foo JYA. Development of a temperature-controlled miniature enclosure for monitoring poor perfusion photoplethysmographic signals. Physiol Meas 2007; 28:N67-75. [PMID: 17827645 DOI: 10.1088/0967-3334/28/9/n01] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A major issue in most optical-based physiological measurements is the effect of temperature fluctuations on the reliability of the acquired data. Studies have suggested that waveforms obtained from the photoplethysmography (PPG) method are temperature sensitive. The conventional approach to tackle these temperature induced variations is to post-signal process the waveforms in the hope of optimizing them to a minimum level for signal pattern and recognition. However, it is known such an approach may alter the PPG characteristics which can be used to identify the pathogenesis and/or pathophysiology of peripheral vascular diseases. Thus, appropriate temperature settings can then facilitate prolonged comparative clinical studies and minimize pathogenic survivability. In this study, a miniature enclosure with a temperature-control feature is proposed to enhance PPG acquisition in a more consistent environment. Eight healthy adults (six male; 26.4 +/- 3.0 yr) were recruited to perform three different test trials to assess the usefulness of the proposed system. The obtained results indicated that without the activation of the temperature-control feature, PPG characteristics acquired from cold fingers can be compromised. Conversely, improvements can be observed when the temperature feature was activated. Hence, the findings herein suggest that this system can be a valuable tool in acquiring PPG waveforms from poorly perfused fingers.
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Affiliation(s)
- Jong Yong Abdiel Foo
- Biomedical Engineering Research Centre, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza 6th Storey, Xfrontiers Block, 637553 Singapore.
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