Page 64 - An Introduction to Laser Tattoo Removal

Chapter 2 – Fundamentals of Laser Tattoo Removal v1.0
While this method may assist in some cases, in reality, it is very difficult to predict the total number of treatments needed. Hence, the Kirby-Desai Scale should only be used as a rough approximation.
Cavitation bubbles
There appears to be some confusion over ‘cavitation’. Many commenters mistakenly say that the gray/white ‘frosting’ which can occurs during laser tattoo treatments is due to cavitation bubbles. This is wrong.
Figure 30: A propellor damaged by cavitation erosion.
Cavitation bubbles are generated by rapid changes in local pressure in water. They are commonly found during the operation of centrifugal pumps, water turbines and particularly in large ships’ propellors where they can cause significant erosion of the metal. These air bubbles are created when the local pressure of the water is reduced to its vapour pressure leading to a rapid expansion of the bubbles.
The bubbles then collapse under external pressure, which leads to the formation of a high- speed microjet of water. These jets impact on the metal propellors causing pitted corrosion.
Ultrasound can also create cavitation bubbles in tissues and is used for in number of treatments including cataract surgery and lithotripsy of kidney and gall stones.
Interestingly, the collapse of cavitation bubbles can generate sound and light, due to a rapid release of stored energy.
However, it is highly unlikely that the cavitation bubbles account for the frosting appearance. This is simply because cavitation bubbles exist very briefly, perhaps for milliseconds, while the frosting may be visible for up to 30 minutes.
This topic is currently part of Mike’s research studies and will be discussed in more detail in a later Chapter of this book.
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Chapter 2 LEVEL A Laser Tattoo Removal
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