In this episode, Lisa and Mike discuss the concept of thermal relaxation time (TRT) and its relevance in laser treatments. They explore the historical context of TRT, tracing its origins back to discussions between physicist Dr. John Parrish and dermatologist Dr. Rox Anderson in the 1980s. The conversation highlights the importance of understanding how heat affects blood vessels and hair follicles during laser procedures. Lisa and Mike also introduce the concept of thermal diffusion time (TDT) and emphasise that the key to effective treatments lies in the denaturation time of stem cells, rather than solely focusing on TRT or TDT.
KEY TAKEAWAYS
This is the time it takes for the temperature of a target (like blood vessels) to drop to 50% of its peak temperature. It is crucial for determining how to effectively use lasers for treatments.
The concept developed by John Parrish and Rox Anderson, which emphasises the importance of matching the laser wavelength to the target's absorption characteristics to achieve effective treatment outcomes.
This is the time required to heat stem cells to a temperature that effectively destroys them. It is more critical than TRT or Thermal Diffusion Time (TDT) when it comes to ensuring the success of hair removal treatments.
The effectiveness of a treatment depends not only on the temperature reached but also on how long that temperature is maintained. Higher temperatures can reduce the necessary time for effective treatment.
Most of the denaturation and chemical processes occur after the laser pulse has finished, meaning that the effects of the treatment can continue even after the energy delivery has stopped.
BEST MOMENTS
"The whole point of the thermal relaxation time calculation was to say, let's confine the thermal energy within the blood so that it doesn't spread out everywhere during the pulse."
"If you're trying to kill a hair follicle, we know that you have to basically kill the stem cells."
"We don't care about TRT. Herein lies the problem. If you're basing your timings on a relaxation time, which is a cooling time of the hair, they are irrelevant."
"The higher the temperature, the shorter the time you need to cook. So at 80 degrees, you might need one millisecond. 90 degrees, you might need 0.1 millisecond."
"Most of the actual chemical process of denaturation and cooking occurs after the pulses, not during."
ABOUT THE HOSTS
Mike began his career in medical lasers in 1986 with a physics degree and a post-grad in bioengineering. He helped develop the scar-free removal of tattoos using a Q-Switched Ruby Laser in Glasgow, and the world's first IPL system. Known well in the industry for his hard truths, no BS attitude and logical answers. As the author of three books, articles for medical journals, a well read blog, a Laser Protection Advisor and contributor to the BMLA, Mike is the Laser Guru.
Lisa's claim to laser fame is being Mike's daughter. Growing up with lasers and never avoiding a physics lesson from her Dad, it was natural to enter the industry. Leaving a corporate career with a baby to jump into self employed life came with challenges. Despite that Lisa has been well recognised for her teaching style, practical tips, bringing the compassion to the science, and laser mentoring.
Instagram: @dermalase_lasertraining
https://mikemurphyblog.com
https://www.dermalasetraining.com
This Podcast has been brought to you by Disruptive Media. https://disruptivemedia.co.uk/