I recently read an excellent article entitled “Effects of picosecond laser on the multi-colored tattoo removal using Hartley guinea pig: A preliminary study” by some researchers in South Korea.
You can obtain a copy here.
In it, they compare the use of two picosecond lasers and a nanosecond Nd:YAG laser. In all, they use three wavelengths – 532, 755 and 1064 nm, with a range of spot diameters and fluences (see table 1).
They tattooed some guinea pigs and then treated them only once with these lasers, and compared the results.
They show a series of photos of various coloured inks before and after treatment. They then calculated a percentage loss in ink after a three week period and present them in a table.
I have taken this data and drawn up another table showing the order of effectiveness of each wavelength/pulsewidth combination on the coloured inks – see table 2:
I have colour-coded the results to make them easier to interpret.
Clearly, for all colours, the picosecond lasers work more efficiently than their nanosecond counterparts (top row). However, interestingly, the 532 nanosecond output appears to be very useful in treating red, orange, yellow, green and blue inks (row 2) – although, not so good at black!
The picosecond lasers then come in strongly in row 3 for all colours.
But, perhaps most interesting, is that the alexandrite laser (755 nm) appears to be poor for all colours, except green and blue, when compared with the other systems (including the nanosecond laser).
These are very interesting results. I think they show that picosecond lasers are ‘generally’ better at inducing ink removal than nanosecond lasers. But, the 532 nanosecond output appears to do very well for most colours – except black!
I have two comments on this study:
- The range of fluences is quite large, from 0.8 to 3.4 J/cm^2. It would have been better if they had used the same fluence across the study;
- I think they should have left a longer period following the treatment. Anecdotal evidence indicates that there is more clearance around six to eight weeks post-treatment.
Given the extortionate cost of picosecond lasers, the above study might suggest that a good, reliable nanosecond laser might be ‘nearly as good’ as a very expensive picosecond laser…
What do you think?
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