Dale
An Oral History of Evidence Based Medicine
Richard Smith discusses the history of Evidence-based Medicine with Iain Chalmers, Kay Dickersin, Paul Glasziou, Muir Gray, Gordon Guyatt, Brian Haynes, Drummond Rennie and David Sackett. Watch the videos at http://ebm.jamanetwork.com.
Pathological Science in Laser Medicine
“Most alternative laser medicine is not supported by basic physics, and cannot be reproduced by mainstream researchers. If it were reproducible it would not be called alternative medicine, and it would not require a belief system for it to work.”
The increased interest in Alternative Laser Medicine (ALM), predominately Low Level Laser Therapy (LLLT), and its applications is mostly a product of pathological science, and partly due to a financial incentive to sell easy solutions for difficult problems.
ALM is well established in the veterinary field where patients cannot describe their experience, and the level… Continue reading
The Myth of Photon Recycling
Photon recycling is basically an attempt to improve the efficiency of poorly designed devices. The small amount of energy provided by recycled photons can be achieved by simply turning the fluence of the device up just a few per cent. Additionally, photon recycling results in unwanted heat at the surface and almost no increase in the effectiveness at the intended target. This results in added discomfort and no increase in clinical efficacy. A best design practice for lasers and flashlamps is to reduce or eliminate this unwanted recycled light. A better choice is to increase the fluence a small amount,… Continue reading
Absorption spectrum of tissue
Beam profiles: Top hat vs. gaussian
DC-excited vs. RF-excited CO2 lases
IPL pulse shape: physics vs. marketing
There is a some of discussion on the interneet forums about IPL pulsing formats and websites with some manufacturers claiming that their IPL device delivers a square pulse that provides constant energy to tissue during the exposure, and is clinically better. This claim is not quite accurate, somewhat misleading. and an example of marketing leading the physics.
The square pulse as advertised for these devices provides a constant power level, and constant irradiance at the tissue, not constant energy. The energy or fluence delivered is accumulated over time period of the pulse, and is the integral of this… Continue reading
Ultrapulse, Superpulse or chopped?
These are marketing terms. All modern medical CO2 lasers are pulsed by electronic gating, and all can run continuously (referred to as CW) for short time periods. Chopped is a historical term that refers to mechanically gating the laser beam with a mechanical shutter of that actually chopped the beam.
All modern lasers are electronically gated or chopped. In general RF-excited lasers are designed to operate at a CW fixed power level, (240w for the Ultrapulse), and are pulsed by gating their CW power level. DC-excited lasers are also pulsed by electronic gating, but have the ability for superpulse… Continue reading
What is the best spot size fractional treatment?
Anatomy of an IPL hand piece
