Page 23 - Mike's published articles

Fig. 4. Impact velocities on the glass slide as a function of penetration depths into the glass slides.
site glass. This may be evident in Figure 5 where the optically distorted peripheral areas appear to indicate a melting and/or fracturing of the glass. The melted ink and glass then mix forming the observed “insects,” before the glass rapidly solidifies. Note the significant degree of symmetry suggesting a fairly homogeneous diffusion of ink.
Only around 35% of the tested slides exhibited embedded ink fragments following treatments. Not all treatment sites appear to eject ink particles which may be due to deeper ink targets. These tattoos will receive less energy than superficial ones and, consequently, will generate less powerful explosive photoacoustic reactions, with lower kinetic energies within the fragments. In addition, non- black ink will generate lower kinetic energies due to their lower energy absorption. This may explain why coloured inks were not seen within the slide samples.
CONCLUSION
It appears that “splatter” includes aggregates/ particles of tattoo ink and may also carry epidermal
Fig. 5. An impact zone in a glass slide following laser treatment (⇥70 magnification). The darker areas are ink aggregates with clear evidence of alterations, probably mechanical and thermal, to the glass surrounding the central impact zone.
and dermal tissue [15,16], including blood, with the high velocity ink particles providing a transmission mode. The possibility of transmitted viable bacterial and viral particles must also be a concern for all QS and picosecond laser operators (although no evidence has been found of this to the author’s knowledge, as yet). The use of physical barriers such as Tegaderm1, Second Skin1, and Vigilon1 suggests that this concern is not new. However, the speed of ejection of these particles was not previously known and it is possible that these barriers may prove ineffective, under these conditions. It is entirely possible that the high temper- atures within the hot ink aggregates destroy the viability of any potential viruses/bacteria. Clearly, further work needs to be done to determine the potential biohazard risk from these ejected aggregates.
It appears that the glass slide method [19] may be the best way to prevent possible transmission of these particles. However, a glass “harder” than that used in this study may need to be used routinely to prevent contamination of the treatment site with glass particles from the slides. No patients reported any undue effects or irritations following the use of this technique. One downside to this technique is the extra time required to treat larger areas, using a glass slide, however, with a larger glass slide (55 ⇥ 100 mm) this was not found to be significant.
It is probable that, in some cases, ink aggregates may have become embedded in the skin of laser operators. While this may pose a very small probability of cross- infection, it is still a risk. Conventional surgical masks may not offer suitable protection due to the very small size and high speed of the ejected particles. Given that there are currently thousands of Q-switched lasers across the world today, carrying out potentially millions of tattoo removal treatments every year, the risk is very real. The same is true for the newer picosecond lasers which generate higher peak powers than the Q-switched variety.
ACKNOWLEDGMENTS
The author would like to acknowledge the important assistance of James Duncan and Aaron Carr for many fruitful discussions. In particular, the author wishes to thank Lesley Murphy for noticing the image on the slide in Figure 2. Also acknowledged is the assistance of Per-Arne Torstensson and Dr Awfa Paulina for their insights and discussions. Many thanks also to Robert Donnelly for the use of his microscope.
REFERENCES
1. Ritchie A. The Use of a Q-Switched Pulsed Ruby Laser to Treat Blue/Black Tattoo: An In Vitro and Clinical Trial. Ph.D. Thesis, Glasgow, Scotland: University of Strathclyde; 1982.
2. ReidWH,McLeodPJ,RitchieA,Ferguson-PellM.Q-switched ruby laser treatment of black tattoos. Br J Plast Surg 1983;36:455–459.
3. TaylorCR,GangeRW,DoverJS,etal.Treatmentoftattoosby Q-switched ruby laser. A dose-response study. Arch Dermatol 1990;126(7):893–899.
4. Reid WH, Miller ID, Murphy MJ, Paul JP, Evans JH. Q-switched ruby laser removal of tattoo: A 9-year review. Brit J Plast Surg 1990;43:663–669.
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