DOI: 10.1002/lsm.1900090414. Time constants in thermal laser medicine

Time constants in thermal laser medicine

10.1002/lsm.1900090414

Crossref journal-article

Wiley

Lasers in Surgery and Medicine (311)

Abstract

AbstractTemperature rise of laser‐irradiated tissue due to direct absorption of laser light is related to laser parameters (power, spot size, irradiation time, and repetition rate) and tissue parameters (absorption and scattering coefficients, density, heat capacity, and thermal conductivity). Solutions to the bio‐heat equation are approximated by introducing axial (z) and radial (r) time constants for heat conduction that represent two parallel channels for heat conduction. These axial (τz) and radial (τr) time constants are found proportional to squared distances (zO2, rO2) that represent the extent of axial and radial temperatures respectively. For convenience, zO and rO are approximated to the axial and radial extent of laser light in the tissue. The resulting solution of the bioheat equation, expressed as temperature rise as function of time and position, is obviously exact for irradiation times short compared to τz, τr (adiabatic heating), but is also a quite reasonable approximation up to irradiation times three times the overall time constant. Comparison with (exact) numerical computations show that this holds for all ratios of (light) penetration depth to laser‐beam radius; for strongly scattering materials, smaller laser beams give better predictions than do larger laser beams. Several examples of clinical relevance are discussed, such as multiple‐laser‐pulse irradiation of high‐ and low‐absorbing tissues and laser treatment of port‐wine stains, with some unexpected results that also show potential clinical relevance.

Bibliography

van Gemert, M. J. C., & Welch, A. J. (1989). Time constants in thermal laser medicine. Lasers in Surgery and Medicine, 9(4), 405â421. Portico.

Authors 2

Martin J. C. van Gemert (first)
A. J. Welch (additional)

References 20 Referenced 168

10.1007/BF02030737
10.1007/978-1-4684-8285-0_4
10.1109/TBME.1980.326619
10.1109/TBME.1979.326509
10.1109/JQE.1987.1073238
10.1109/TBME.1976.324632
10.1007/978-1-4684-8550-9_5
{'key': 'e_1_2_1_9_2', 'first-page': '634', 'article-title': 'Development of criterion for skin burns', 'volume': '45', 'author': 'Takata AN', 'year': '1974', 'journal-title': 'Aerospace Med'} / Aerospace Med / Development of criterion for skin burns by Takata AN (1974)
10.1088/0031-9155/27/9/001
{'key': 'e_1_2_1_11_2', 'volume-title': 'Wave Propagation and Scattering in Random Media', 'author': 'Ishimaru A', 'year': '1978'} / Wave Propagation and Scattering in Random Media by Ishimaru A (1978)
KeijzerM JacquesSL PrahlSA WelchAJ.Light distributions in artery tissue: Monte Carlo simulations for finite‐diameter laser beams. Submitted.
10.1175/1520-0469(1976)033<2452:TDEAFR>2.0.CO;2
MotamediM. Private communication.
10.1002/bjs.1800740539
10.1002/lsm.1900060116
{'key': 'e_1_2_1_16_3', 'first-page': '218', 'article-title': 'Treatment of port‐wine stains at 577nm: Clinical results', 'volume': '21', 'author': 'Tan OT', 'year': '1987', 'journal-title': 'Med Instrum'} / Med Instrum / Treatment of port‐wine stains at 577nm: Clinical results by Tan OT (1987)
10.1111/1523-1747.ep12535052
10.1002/lsm.1900040410
10.1088/0031-9155/30/6/007
10.1002/lsm.1900010310

Dates

Type	When
Created	18 years, 6 months ago (March 3, 2007, 6:01 a.m.)
Deposited	1 year, 10 months ago (Oct. 22, 2023, 1:24 a.m.)
Indexed	1 month ago (July 31, 2025, 11:47 p.m.)
Issued	36 years, 8 months ago (Jan. 1, 1989)
Published	36 years, 8 months ago (Jan. 1, 1989)
Published Online	19 years, 10 months ago (Oct. 19, 2005)
Published Print	36 years, 8 months ago (Jan. 1, 1989)

Funders 0

None

BibTeX

@article{van_Gemert_1989, title={Time constants in thermal laser medicine}, volume={9}, ISSN={1096-9101}, url={http://dx.doi.org/10.1002/lsm.1900090414}, DOI={10.1002/lsm.1900090414}, number={4}, journal={Lasers in Surgery and Medicine}, publisher={Wiley}, author={van Gemert, Martin J. C. and Welch, A. J.}, year={1989}, month=jan, pages={405–421} }

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