spectral shift presentation

7/27/2019 Spectral Shift Presentation

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Confirmation of Spectral Jitter: A Measured

Shift in the Spectral Distribution of IntensePulsed Light Systems using a Time-Resolved

Spectrometer during Exposure and Increased

Fluence

Caerwyn Ash1, Godfrey Town2, Marc Clement, PhD1

1. School of Medicine, Swansea University, Wales, SA2 8PP

2. Laser Protection Adviser, GCG Healthcare, UK, RH16 2LT

2009


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Statement of Disclosure

The following potential conflict of interest relationshipsare germane to my presentation:

Salary and test equipment loan:CyDen Ltd., Wales

Travel grant:Swansea University, Wales

2009


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Background

Time-resolved measurement shows a

spectral distribution shift in an intense pulsed

light systemE Eadie, P Miller, T Goodman, & H Moseley.

Lasers in Medical Science 2007

Square Pulse

Clinical differences reported amongst IPL systems despite comparablesystem parameters

Spectral shift / Spectral Jitter first described in 2004

Relevance of the Structure of Time

Resolved Spectral Output to Light Tissue

Interaction Using Intense Pulsed Light (IPL)

C Ash, G Town, P Bjerring

Lasers in Surgery and Medicine 2007


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Materials and Methods

Ocean Optics HR2000+ Spectrometer

1ms Time resolved capability (0.35nm resolution)

Wavelength points from 300nm to 1000nm in 50nm intervals

Spectral distribution plotted with 1ms resolution or pulse

number in the case of multiple pulses Measurements taken with common system parameters

19 systems measured for study

System output grouped into 4 categoriesSquare pulseFree discharge

Close pulse stacking

Spaced pulse stacking


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Results - Square Pulse

Sharp 530nm filter

Single pulse 25ms in duration

Consistent distribution ofwavelengths during pulse

duration


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Results -Free Discharge

Poorly filtered emission 17%energy below 500nm

Single pulse 18ms in duration

Spectral distribution changesduring pulse duration

650nm increase

450, 500, 550, 600, 700nmdecrease


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Results -Close Pulse Stacking

Sharp 600nm filter

7 pulses stacked closelytogether, decaying fluence

900, 950nm increase

600, 650, 700nm decreasefrom first pulse to last


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Results -Close Pulse Stacking

Sharp 620nm filter

Unique analogue pulse profileof number of pulses of 1ms

separated by 3ms dwell

periods.

900, 950nm increase

650, 700nm decrease fromfirst pulse to last


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Results -Spaced Pulse Stacking

Sharp 650nm filter

5 pulses spaced apart of shortduration high fluence

Spectral distributionconsistent flashlampimpedance reverses during off

time


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Results Increasing Fluence

Square Pulse Free Discharge


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Conclusions

A change in spectral distribution both within a pulse andincreasing fluence was verified.

Spectral Shift more prominent with free discharge systems.

May not be clinically significant as fluence dosimetry is amuch greater factor. Epilation is unlikely to be effected due to

broad melanin absorption. Spectral shift could effect treatment outcomes. A systemcould be modelled and implemented, particularly where

absorption characteristics vary.


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Conclusions

Many IPL systems incorporate high cut off filters to preventepidermal absorption, thus concealing the decaying effect in

the shorter wavelengths of the flashlamp

Porphyrin and epidermal absorption possibly effected


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Acknowledgments

Swansea UniversitySingleton Park

Swansea

SA2 8PP

Wales, UK

www.swan.ac.uk

CyDen LimitedTechnium

Kings Road

Swansea

UK

SA1 8PHwww.cyden.co.uk


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Thank You

Email: [email protected]


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Prowave 770

Program A - 4 pulses total

20ms on time

Program B, 6 pulses total

36ms on time

Program C,14 pulses total

100ms on time


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