James Carroll, THOR Photomedicine Ltd This work is distributed

© 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

http://www.thorlaser.com


http://creativecommons.org/licenses/by-nc-nd/3.0/




http://www.thorlaser.com/downloads/810nm_penetration.pdf





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


Objective

• To measure the irradiance in the region of a thoracic facet joint in a pig

3


Materials & Methods

4


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


Part 1. Single point vs cluster

Are 5 x single point laser treatments the same as 5 lasers at once?

6


Materials

7


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


Part 2. The effect of spot size

10



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


Part 3. Laser vs LED

13


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


Part 3. The effect of pressure

15


Fibre0.9mm dia0.0063cm2


Fibre0.9mm dia0.0063cm2


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


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



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


0

1

2

3

1.4

1

2.4


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



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


Limitations

• No accounting for W/cm3 (≈ ten times higher readings expected had isotropic detector been used)

• Fibre movement• Pig not a human

23


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












Documents

James Carroll, THOR Photomedicine Ltd This work is distributed