Investigación de láser: Dosis, penetración, abstractos

Referencia

Photomed Laser Surg. 2012 Dec;30(12):688-94. doi: 10.1089/pho.2012.3306. Epub 2012 Oct 1.


Skin penetration time-profiles for continuous 810 nm and Superpulsed 904 nm lasers in a rat model.

Joensen J, Ovsthus K, Reed RK, Hummelsund S, Iversen VV, Lopes-Martins RÁ, Bjordal JM.

Author information

Abstract

Objectives: The purpose of this study was to investigate the rat skin penetration abilities of two commercially available low-level laser therapy (LLLT) devices during 150 sec of irradiation.

Background Data: Effective LLLT irradiation typically lasts from 20 sec up to a few minutes, but the LLLT time-profiles for skin penetration of light energy have not yet been investigated.

Methods: Sixty-two skin flaps overlaying rat's gastrocnemius muscles were harvested and immediately irradiated with LLLT devices. Irradiation was performed either with a 810 nm, 200 mW continuous wave laser, or with a 904 nm, 60 mW superpulsed laser, and the amount of penetrating light energy was measured by an optical power meter and registered at seven time points (range, 1-150 sec).

Results: With the continuous wave 810 nm laser probe in skin contact, the amount of penetrating light energy was stable at ∼20% (SEM±0.6) of the initial optical output during 150 sec irradiation. However, irradiation with the superpulsed 904 nm, 60 mW laser showed a linear increase in penetrating energy from 38% (SEM±1.4) to 58% (SEM±3.5) during 150 sec of exposure. The skin penetration abilities were significantly different (p<0.01) between the two lasers at all measured time points.

Conclusions: LLLT irradiation through rat skin leaves sufficient subdermal light energy to influence pathological processes and tissue repair. The finding that superpulsed 904 nm LLLT light energy penetrates 2-3 easier through the rat skin barrier than 810 nm continuous wave LLLT, corresponds well with results of LLLT dose analyses in systematic reviews of LLLT in musculoskeletal disorders. This may explain why the differentiation between these laser types has been needed in the clinical dosage recommendations of World Association for Laser Therapy.


Photomedicine and Laser Surgery Volume 31, Number 4, 2013

Penetration of Laser Light at 808 and 980nm in Bovine Tissue Samples

Donald E. Hudson, BSEE, Doreen O. Hudson, BS, CET, James M. Wininger, BSEE, and Brian D. Richardson, BA, JD


Abstract

Objective: The purpose of this study was to compare the penetration of 808 and 980nm laser light through bovine tissue samples 18–95mm thick.

Background Data: Low-level laser therapy (LLLT) is frequently used to treat musculoskeletal pathologies. Some of the therapeutic targets are several centimeters deep.

Methods: Laser light at 808 and 980nm (1 W/cm2) was projected through bovine tissue samples ranging in thickness from 18 to 95 mm. Power density measurements were taken for each wavelength at the various depths.

Results: For 808 nm, 1 mW/cm2 was achieved at 3.4 cm, but for 980 nm, 1 mW/cm2 was achieved at only 2.2 cm depth of tissue.

Conclusions: It was determined that 808nm of light penetrates as much as 54% deeper than 980nm light in bovine tissue.


Skin Penetration Time-Profiles for Continuous 810nm and Superpulsed 904nm Lasers in a Rat Model

Jon Joensen, P.T., M.Sc.,1,2 Knut Øvsthus, MIng, Ph.D.,3 Rolf K. Reed, M.D., Ph.D.,4, Steinar Hummelsund, P.T., M.Sc.,1 Vegard V. Iversen, Phys., Ph.D.,5, Rodrigo A´ lvaro Branda˜o Lopes-Martins, Ph.D.,6 and Jan Magnus Bjordal, P.T., Ph.D.1,2

Objective: The purpose of this study was to investigate the rat skin penetration abilities of two commercially available low-level laser therapy (LLLT) devices during 150 sec of irradiation.

Background Data: Effective LLLT irradiation typically lasts from 20 sec up to a few minutes, but the LLLT time-profiles for skin penetration of light energy have not yet been investigated.

Materials and Methods: Sixty-two skin flaps overlaying rat’s gastrocnemius muscles were harvested and immediately irradiated with LLLT devices. Irradiation was performed either with a 810 nm, 200mW continuous wave laser, or with a 904 nm, 60mW superpulsed laser, and the amount of penetrating light energy was measured by an optical power meter and registered at seven time points (range, 1–150 sec).

Results: With the continuous wave 810nm laser probe in skin contact, the amount of penetrating light energy was stable at *20% (SEM – 0.6) of the initial optical output during 150 sec irradiation. However, irradiation with the superpulsed 904 nm, 60mW laser showed a linear increase in penetrating energy from 38% (SEM – 1.4) to 58% (SEM – 3.5) during 150 sec of exposure. The skin penetration abilities were significantly different ( p < 0.01) between the two lasers at all measured time points.

Conclusions: LLLT irradiation through rat skin leaves sufficient subdermal light energy to influence pathological processes and tissue repair. The finding that superpulsed 904nm LLLT light energy penetrates 2–3 easier through the rat skin barrier than 810nm continuous wave LLLT, corresponds well with results of LLLT dose analyses in systematic reviews of LLLT in musculoskeletal disorders. This may explain why the differentiation between these laser types has been needed in the clinical dosage recommendations of World Association for Laser Therapy.


The recommended dosage (WALT) for anti inflammatory effect

Laser classes 3 or 3 B, 780 -860nm GaAlAs Lasers. Continuous or pulse output less than 0.5 Watt Energy dose delivered to the skin over the target tendon or synovia

Tendinopathies Points/cm2 Joules Notes
Carpal-tunnel 2-3 12 Minimum 6 Joules per point
Lateral epicondylitis 1-2 4 Maximum 100mW/cm2
Biceps humeri c.l. 1-2 8
Supraspinatus 2-3 10 Minimum 5 Joules per point
Infraspinatus 2-3 10 Minimum 5 Joules per point
Trochanter major 2-4 10
Patellartendon 2-3 6
Tract. Iliotibialis 2-3 3 Maximum 100mW/cm2
Achilles tendon 2-3 8 Maximum 100mW/cm2
Plantar fasciitis 2-3 12 Minimum 6 Joules per point

Arthritis Points/cm2 Joules Notes
Finger PIP or MCP 1-2 6
Wrist 2-4 10
Humeroradial joint 1-2 4
Elbow 2-4 10
Glenohumeral joint 2-4 15 Minimum 6 Joules per point
Acromioclavicular 1-2 4
Temporomandibular 1-2 6
Cervical spine 2-4 15 Minimum 6 Joules per point
Lumbar spine 2-4 40 Minimum 8 Joules per point
Hip 2-4 40 Minimum 8 Joules per point
Knee medial 3-6 20 Minimum 5 Joules per point
Ankle 2-4 15

Laser classes 3 or 3B, 904 nm GaAs Lasers (Peak pulse output more than 1 Watt) Energy dose delivered to the skin over the target tendon or synovia

Tendinopathies Points/cm2 Joules Notes
Carpal-tunnel 2-3 4 Minimum 2 Joules per point
Lateral epicondylitis 1-2 1 Maximum 100mW/cm2
Biceps humeri c.l. 1-2 2
Supraspinatus 2-3 3 Minimum 2 Joules per point
Infraspinatus 2-3 3 Minimum 2 Joules per point
Trochanter major 2-3 2
Patellartendon 2-3 2
Tract. Iliotibialis 2-3 2 Maximum 100mW/cm2
Achilles tendon 2-3 2 Maximum 100mW/cm2
Plantar fasciitis 2-3 3 Minimum 2 Joules per point

Arthritis Points/cm2 Joules Notes
Finger PIP or MCP 1-2 2
Wrist 2-3 3
Humeroradial joint 1-2 2
Elbow 2-3 3
Glenohumeral joint 2-3 6 Minimum 2 Joules per point
Acromioclavicular 1-2 2
Temporomandibular 1-2 2
Cervical spine 2-3 6 Minimum 2 Joules per point
Lumbar spine 2-3 10 Minimum 4 Joules per point
Hip 2-3 10 Minimum 4 Joules per point
Knee anteromedial 2-4 6 Minimum 2 Joules per point
Ankle 2-4 6

Daily treatment for 2 weeks or treatment every other day for 3-4 weeks is recommended Irradiation should cover most of the pathological tissue in the tendon/synovia.

Tendons


Start with energy dose in table, then reduce by 30% when inflammation is under control (Does not apply for carpal tunnel tendo synovitis)

Therapeutic windows range from typically +/-50% of given values Recommended doses are based on ultrasonographic measurements of depths from skin surface and typical volume of pathological tissue and estimated optical penetration for the different laser types in caucasians.

Disclaimer: The list may be subject to change at any time when more research trials are being published. World Association of Laser Therapy is not responsible for the application of laser therapy in patients, which should be performed at the therapist/doctor`s discretion and responsibility

Revised August 2005