© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
1
James Carroll, THOR Photomedicine Ltd
This work is distributed under license under a Creative Commons
Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Original file located here
http://en.wikipedia.org/wiki/Creative_Commons_licenses
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Background
• LLLT is commonly used for treating musculoskeletal pain• Some of the targets are several cm deep
• How much light at the surface of the skin is required to produce adequate irradiance at the target
• What is the effect of pressure
2
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Objective
• To measure the irradiance in the region of a thoracic facet joint in a pig
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© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Materials & Methods
4
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
810nm 200mW laser penetration depth
Part 1. Single point vs cluster
Part 2. The effect of spot size
Part 3. LED vs laser
Part 4. The effect of pressure
5
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Part 1. Single point vs cluster
Are 5 x single point laser treatments the same as 5 lasers at once?
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© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Materials
7
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Methods
8
6mm dia0.28cm2
Power meter detector Various layer of bacon
Bacon thickness confirmed with digital vernier
Single vs laser cluster
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM9
0
1
2
3
Bacon thickness 30mm
0.62
2.95
5 x 200mW laser Cluster200mW single laser
Irra
dian
ce m
W/c
m2
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Part 2. The effect of spot size
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© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM11
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Smaller spot size = greater penetration
12
Irra
dian
ce m
easu
red
thro
ugh
3cm
bac
onm
W/c
m2
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
66.6 8 3.4 .9 .2
0.530.57
0.65
0.74
0.93
810nm W/cm2
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Part 3. Laser vs LED
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© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Results
14
0
1
2
3
Bacon thickness 30mm
1.7
0.62
2.95
Laser ClusterLaser SingleLED Cluster
Irra
dian
ce m
W/c
m2
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Part 3. The effect of pressure
15
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM16
Fibre0.9mm dia0.0063cm2
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM17
Fibre0.9mm dia0.0063cm2
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Power Density @ 3cm
18
0
2.5
5
7.5
10
4.7
3.1
7.5
Irra
dian
ce m
W/c
m2
810nm 5 x 200mW 5W./cm2 810nm 200mW 5W./cm256 x 660nm 10mW/50mWcm2 35 x 48 x 850nm/150mW/cm2
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Power Density @ 3cm
19
0
2.5
5
7.5
10
6.2
4.7
5.6
3.1
10.2
7.5
Irra
dian
ce m
W/c
m2
No
Pres
sure
Pres
sure
No
Pres
sure
Pres
sure
No
Pres
sure
Pres
sure
810nm 5 x 200mW 5W./cm2 810nm 200mW 5W./cm256 x 660nm 10mW/50mWcm2 35 x 48 x 850nm/150mW/cm2
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Power Density @ 5cm
20
Irra
dian
ce m
W/c
m2
No
Pres
sure
Pres
sure
No
Pres
sure
Pres
sure
No
Pres
sure
Pres
sure
810nm 5 x 200mW 5W./cm2 810nm 200mW 5W./cm256 x 660nm 10mW/50mWcm2 35 x 48 x 850nm/150mW/cm2
0
1
2
3
1.4
1
2.4
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Power Density @ 5cm
21
0
1
2
3
2
1.4
1.8
1
3.1
2.4
Irra
dian
ce m
W/c
m2
No
Pres
sure
Pres
sure
No
Pres
sure
Pres
sure
No
Pres
sure
Pres
sure
810nm 5 x 200mW 5W./cm2 810nm 200mW 5W./cm256 x 660nm 10mW/50mWcm2 35 x 48 x 850nm/150mW/cm2
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Conclusion
• Pressure increases irradiance • 5 lasers are better than 1 (the power density accumulates due to
combined effect of scatter)
• 810nm 1W (5 x 200mW) achieves 10mW/cm2 @ 3cm• 810nm 1W (5 x 200mW) achieves 1mW/cm2 @ 5cm• Uncertain how much irradiance or fluence required at the facet
joints
22
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
Limitations
• No accounting for W/cm3 (≈ ten times higher readings expected had isotropic detector been used)
• Fibre movement• Pig not a human
23
© 2010 THOR Photomedicine Ltd WWW.THORLASER.COM
24
James Carroll, THOR Photomedicine Ltd
This work is distributed under license under a Creative Commons
Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Original file located here
http://en.wikipedia.org/wiki/Creative_Commons_licenses