LLLT penetration in Human Achilles

Project summary

Objective: There are few LLLT studies dealing with energy penetration in biologic tissue. The penetration depth and energy loss has been investigated in some studies (Kolarova et al., 1999; Enwemeka, 2001; Topping et al., 2001; Esnouf et al., 2007). The penetration profile during an irradiation session is poorly studied. Recently we published a study on the penetration profile for energy from infrared class 3B lasers, in rat skin (Joensen et al., 2012). The purpose of this project is to investigate the penetration time-profile from LLLT irradiation in human tissue. The amount of energy penetrating joint and tendon is monitored.

Method: This project is a basic research study on in situ human tissue. The study has a single-factor experimental design and includes repeated measurements. The penetration profile of energy from LLLT is recorded during 150 seconds of irradiation.

Subjects: The first group included is a sample of 50 healthy subjects, (=100 Achilles/5.fingers).

(In the autumn 2015 we start with a group of young people). Subjects are recruited from the student population at Bergen University College.

Instruments: Two commercial infrared class 3B lasers: 810 nm wavelength laser (Thor LX2, Thor UK), operating in continuous mode with 200 mW MOP, spot size 0.0314 cm². 904 nm wavelength laser (MID-laser, Irradia Sweden), operating in a superpulsed mode: Peak power 20 W, pulse train frequency 6 kHz and pulses 100 nsec (10^-9 sec) width (=30.000 pulses per sec), 60 mW MOP, spot size 0.0364 cm².

Optical Power-meter system, (Thorlabs Instruments, NJ, USA).

Thermographic camera, ThermaCAM S65HS (Flir System, USA), and ancillary software (ThermaCAM Researcher Pro 2.8 SR-1).

Real-Timed Ultrasonography, Logiq-S8, (GE Healthcare, Minneapolis, USA).

Outcome measure: Amount of energy penetrating human Achilles during irradiation is monitored by Optical Power Meter. Tissue thickness and skin temperature are measured by RTUS and Thermography, respectively.

Study 1: The aim of this study is to investigate the effect of cooling on energy penetration from LLLT, in Achilles. Energy penetration from two lasers is measured before and after 20 minutes with ice.

Study 2: The aim of this study is to compare energy penetration from LLLT in Achilles with the tendon at rest versus stretched. Energy penetration from two lasers in Achilles is monitored in two conditions (at rest and stretched).

References:

ENWEMEKA, C. S. (2001). Attenuation and penetration depth of red 632.8 nm and invisible infrared 904 nm light in soft tissues. Laser Therapy, 13, 95-101.

ESNOUF, A., WRIGHT, P. A., MOORE, J. C. & AHMED, S. (2007). Depth of penetration of an 850nm wavelength low level laser in human skin. Acupunct Electrother Res, 32, 81-6.

JOENSEN, J., OVSTHUS, K., REED, R. K., HUMMELSUND, S., IVERSEN, V. V., LOPES-MARTINS, R. A. & BJORDAL, J. M. (2012). Skin penetration time-profiles for continuous 810 nm and Superpulsed 904 nm lasers in a rat model. Photomed Laser Surg, 30, 688-94.

KOLAROVA, H., DITRICHOVA, D. & WAGNER, J. (1999). Penetration of the laser light into the skin in vitro. Lasers Surg Med, 24, 231-5.

TOPPING, A., GAULT, D., GROBBELAAR, A., SANDERS, R., GREEN, C. & LINGE, C. (2001). Does low penetration of human skin by the normal mode ruby laser account for poor permanent depilatory success rates? Lasers Med Sci, 16, 224-9.