Today’s IPL Technology and
Measuring Key Parameters
Caerwyn Ash
School of Medicine, Swansea University
Aesthetics Today
Birmingham NEC
4th October 2008
Statement of Disclosure
The following potential conflict of
interest relationships are germane
to my presentation: Salary,
equipment, and travel expenses
paid by CyDen Ltd.
Intense Pulsed Light Systems
How They Work! • Flashlamp based system
• Visible light heat highly absorbing melanin in hair without
heating surrounding tissue matrix.
• Pulses within a time duration typically 10’s milliseconds
• Optical filters are used to attenuate harmful wavelengths
Intense Pulsed Light Systems
• Acne Vulgaris
• Hair management – now also on dark skin
• Photodamage Types I, II, (and III with PDT)
• Vascular lesions
• Pigmented lesions
• Psorasis
• Creams and potions
• Breast Firming
Treatments IPL systems are becoming increasingly more versatile treatment devices
Absorption of Chromophores
Absorption of Chromophores
Regulations Because there is no international standard for IPL systems,
we don’t know:
• If the stated fluence values are correct or when the IPL lamp
is out of tolerance?
• If the stated pulse durations are accurate (or relevant)?
• If the pulse ‘square’ (and the spectral ‘footprint’ constant)?
• What the IPL pulse structure means on tissue?
• If the cut-off filters are as claimed?
• If there are any potentially harmful wavelengths?
These published papers expose
some of what we don’t know:
Measuring key parameters of intense pulsed
light (IPL) devices
Town G, Ash C, Eadie E, Moseley H. J Cosmetic
Laser Therapy 2007; 9:3:148-160.
Relevance of the structure of time-resolved
spectral output to light-tissue interaction
using intense pulsed light (IPL)
Ash C, Town G and Bjerring P. Lasers in
Surgery and Medicine 2008; Vol 40:2: 83-92.
Key Parameters
Fluence – Energy density (J/cm2)
Spectral Distribution – intensities of the range of
wavelengths
Pulse duration – the total period of light emission
Beam profile – is the distribution of discharged energy
across the treatment area
Lamp discharge profile - is an important factor as it
bears importance to the change in fluence with the pulse
duration
Time resolved spectral data – shows the change in
spectral distribution and fluence with time
Measurements made for
Comparison Study • 18 different devices from 15 different manufacturers and
36 applicators (different cut-off filters) from USA, UK, Israel, Sweden, Switzerland, China and Italy were tested by the authors.
• Data on fluence, pulse duration, pulse structure, cut-off filters and UV content was gathered on-site between patient appointments over a 6-month period in clinics where devices were in daily use.
• Manufacturers’ information was collected from user manuals, company web sites and literature for verification.
Measured Fluence
• Fluence measured using an Ophir
energy meter
• Class 4 laser standard states an
industry tolerance of +/- 20%
Flashlamp Physics
• IPL light source is a handmade flashlamp
• A flashlamp deteriorates with every discharge
• Manufacturers limit shot life to prevent energy
decreasing to become clinically ineffective
Comparing Fluence Values
30 IPL applicators were measured at maximum fluence of which
11 were more than 20% below and 8 were more than 10% above
fluence levels given on the device display or claimed in user
manuals, even where brand-new lamps were tested.
Comparing Fluence Values
9 IPL devices out of 18 had applicators that were outside of the standard for medical Class 4 lasers (> +/-20%)
Filter Performance
•Good, sharp 530 nm cut-off filter
• No significant UV.
• Spectrum analysis of light contains
• Discrete line structure
• Continuum radiation.
• Filter position measured different to that
stated
Comparing Average Spectral Output
Of 29 applicators 19 (65%) with cut-off filters that were inaccurate by more than 20 nm versus the claimed cut-off value given by the manufacturer. Only 10 applicators (35%) were within 20 nm of the stated cut-off.
Filter Performance
• Patient dissatisfaction can be caused
epidermal damage caused by significant UV or
blue content.
• Dichroic filters become damaged through long
term use by high energy IPL systems
overloading a thin dichroic coating.
Filter Performance
• Epidermal damage produced by significant UV / blue spectral
content, caused by degraded filter
• Injury causes pain and discomfort - dissatisfaction to patient
• Possible legal proceeding against salon/clinic
Measurement of UV Content
Shorter wavelengths in the ultraviolet region of the spectrum may burn the patient’s skin or may be hazardous to the operator’s eyes and are therefore removed. Of the 30 applicators tested, 6 IPLs measured more than 1% and two measured more than 2% of unwanted UV output below 400 nm when cut-off filters were set significantly higher.
Comparing Electrical Discharge
• Only three systems measured possess a square pulse discharge
• Three systems proved not to have a square pulse
• Most systems utilise simple free discharge
• Others delivery methods stack pulses together to extend pulse duration
Comparing Pulse Duration &
Structure • Only 14 out of 29 pulse duration measurements were
within ±20% of the manufacturers stated or system
displayed values.
• Photodiode measurements of total pulse duration did
not disclose where the effective spectral output
occurred during the pulse.
• Several manufacturers claimed ‘square pulse’ output
without explaining its significance.
• Several manufacturers ‘stacked’ sub-pulses
to achieve a ‘biological’ square pulse.
Comparing Pulse Duration &
Structure
• These images show time resolved profiles of the pulse
durations of five well known wavelengths Dye, Ruby,
Alexandrite, Diode, and Nd:YAG
• Pulse duration is the same for all wavelengths
• Decay of energy during the pulse an important factor
Digital Revolution
Time-resolved spectrum sampled every 1 ms using an Ocean
Optics HR2000+ spectrometer and SpectraSuite software to
demonstrate the stability and efficiency of spectral output for
free-discharge vs. square pulse systems
Free Discharge Square Pulse
Comparing Time-Resolved Spectral
Output
Comparing Time-Resolved
Spectral Output
time resolved video of 1ms frame capture of the difference in
the temporal characteristics of a free discharge and partial
discharge pulse system. Slowed in time to observe changes
25ms Free Discharge Pulse 25ms Square Pulse
Free Discharge
Manufacturer claims a 25ms pulse duration but when
measured using time resolved spectrometer only circa 3ms
of useful energy is present
The anatomical target for hair
removal
• Effective pulse duration for follicular damage = 20-40ms
• Melanin heated to circa 70ºC causes destroys follicular cells
• Surrounding tissue matrix spared from heating effect
• Free discharge systems are not optimum in delivering
energy within such time regime
• Fluence is delivered evenly during the pulse duration
• A controlled square pulse can produce pulse durations that are biologically effective and efficient
• All wavelengths in the spectrum are equally represented during the exposure
• Less adverse reactions
Optimum IPL light pulse
Pulse Stacking
• Fluence decays during the pulse duration
• Pulse stacking is used by certain manufacture to extend total pulse duration
• Close stacked pulses are effectively a single pulse of decaying energy as the off time between pulses are short
• Spectral shift is highly present during exposure
Pulse Stacking
• Fluence varies of each short pulse during the pulse train due to separate capacitors
• Pulse stacking is used by certain manufacturers to extend total pulse duration but with long off times, thermal energy that is absorbed by melanosomes is dissipated to surrounding tissue within off times.
• Greatest number of adverse reactions reported
Summary
• Many manufacturers of IPLs make claims for fluence, pulse duration and spectral emission that are not substantiated as measured by this study - This may lead to increased risk of under- or over-treatment or burn injury to the IPL patient
• Manufacturers operating an ISO 9000 quality system (Medical CE-mark) showed greater consistency of stated and actual values for fluence, pulse duration and spectral cut-off filter accuracy over the stated lifetime of the applicator / lamps
• Square Pulse Systems:
Produce the lowest possible intensity for a given fluence thus minimising discomfort and other side effects such as skin burns
• Free Discharge Systems:
Produce high intensity energy in short pulse durations with spectral shift and less efficient spectral distribution
Summary
• A time-resolved ‘Spectral Footprint’ as shown in these measurements is helpful in determining the true pulse duration and spectral pattern of useful energy for optimized clinical efficiency
• This first serious attempt to measure IPL performance characteristics provides criteria that should be carried to national representatives of the competent regulatory body (IEC) to promote an international standard for measuring intense light devices
Conclusion: Characteristics of
an Optimum IPL System
• Energy output level at least within +/- 20% of stated value, medically CE marked systems have a tendency to provide such tolerance
• Cut off filter should be that stated match the absorbance spectrum of the desired skin chromophore
• Pulse duration should be within close range of the Thermal Relaxation Time, square pulse technology is greatly suited to provide this
• Constant energy level during the entire pulse duration is optimum for maximum heating for follicular structure. Lower energies are required than a variable pulse thus greater patient comfort.
• Patients and operators want professional service choose a business that provides a good experience when using their IPL system
What about home-use IPL and
laser devices?
1 Spectragenics, Tria
2 Homeskinovations, Silkn
3 Rio, Salon laser
4 Radiancy, No No
5 CyDen, MicroPulse
6 GHT Innovation, Epi Flash
What’s on the Market
1
2
3
4
5
6
Home Use Units - Comparison Data
A Review of Home Use Lasers and IPLs for Hair Removal Godfrey Town, Caerwyn Ash
Thank you !