Hand-held pulsed photothermal radiometry system to estimate epidermal temperature rise during laser therapy

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Hand-held pulsed photothermal radiometry system to estimate epidermal temperature rise during laser therapy
November 2006
To cite this article: Byungjo Jung, Chang-Seok Kim, Bernard Choi, J. Stuart Nelson (2006)
Hand-held pulsed photothermal radiometry system to estimate epidermal temperature rise during laser therapy
Skin Research and Technology 12 (4), 292Ò297.
doi:10.1111/j.0909-752X.2006.00175.x

Byungjo Jung1,21Beckman Laser Institute, Irvine, CA, USA, 2Department of Biomedical Engineering, Yonsei University, Wonju, Korea, and , Chang-Seok Kim1,31Beckman Laser Institute, Irvine, CA, USA, 3School of Nano Science and Technology, Pusan National University, Pusan, Korea, Bernard Choi11Beckman Laser Institute, Irvine, CA, USA, and J. Stuart Nelson1
1Beckman Laser Institute, Irvine, CA, USA, 1Beckman Laser Institute, Irvine, CA, USA, 2Department of Biomedical Engineering, Yonsei University, Wonju, Korea, and 3School of Nano Science and Technology, Pusan National University, Pusan, Korea
Address:
Byungjo Jung, Ph.D.
Department of Biomedical Engineering
Yonsei University
234 Maeji, Jeungup-myun
Wonju-si, Gangwon-do, 220-710, Korea
Tel: 82-33-760-2786
Fax: 82-33-763-1953
e-mail: bjung@dragon.yonsei.ac.kr

Abstract
Background/purpose: During laser therapy of port wine stain (PWS) birthmarks in human skin, measurement of the epidermal temperature rise (ΔTepi) is important to determine the maximal permissible light dose. In order to measure ΔTepi on a specific PWS skin site, we developed an AC-coupled hand-held pulsed photothermal radiometry (PPTR) system, which overcomes the in vivo measurement limitations of bench-top systems.

Methods: The developed hand-held PPTR system consists of an infrared (IR) lens, AC-coupled thermoelectrically cooled IR detector, laser hand-piece holder, and positioning aperture. The raw AC-coupled signal was integrated to obtain a higher signal-to-noise ratio (SNR). The experimental temperature difference (ΔT) calibration was compared with theoretical computations. In vitro and in vivo measurements of ΔT were performed with a tissue phantom as a function of radiant exposure and human subject as a function of melanin concentration, respectively.

Results: The integrated AC-coupled signal provided higher SNR as compared with the raw AC-coupled signal. The experimental ΔT calibration resulted in good agreements with the theoretical results. The in vitro and in vivo results also presented good agreements with theory.

Conclusions: A fiber-free, hand-held AC-coupled PPTR system is capable of accurate epidermis temperature rise (ΔTepi) measurements of human skin during pulsed laser exposure.

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