The Depth of Thermal Necrosis AfterSureTouchTM (SoftScanTM) CO2 Laser Scanner

Abstract

BACKGROUND: SureTouch^TM (SoftScan^TM) CO₂ laser scanner has recently been introduced for laser skin resurfacing. It is optomechanical flarshscaner that can be used in conjunction with a lower power CO₂ laser in the continuous mode. The scanner achieves high power by focusing the CO₂ laser beam to a small spot size of 200 µm, and rapidly scans the focused beam over a variety of scan pattern. The scan size can be variable up to 20 mm. dwelling time can be adjustable from 396 to 1000 µsec. There were no previous studies for human tissue effect of this scanner.

OBJECTIVES: To define the optimum laser parameters for maximum aesthetic effect of the scanner and to determine the depth of ablation and the depth of residual thermal injury produced with one to three passes of the optimum laser parameters.

METHODS: Normal skin from both ends of fusiform excision at perioral area for a total of 12 specimens were treated with one pass of the following three different power setting. Square- pattern, 2x2 mm. scan area was set with three different power settings of 11, 15, 20 watts, continuous wave CO2 laser mode. Four

different dwelling times, 396, 485, 591 and 698 µsec were used for each power setting. The distal end of

postauricular donor skin from another patient requiring full thickness skin grafts following Mohs micrographic surgery for a total of 6 specimens were treated with one to three passes of 11 watts and 2 dwelling times, 396 and 485 µsec. Histologic studies were evaluated by light microscopy and micrometer.

RESULTS: The depth of thermal necrosis after one pass of SureTouch™co2 laser scanner are between

5 and 100 µm. The constant ablation depth after one pass of all parameters measured about 20-50 µm. Increasing the dwelling time and power setting resulted in a corresponding increase in the depth of thermal necrosis. The depth of ablation and residual thermal injury after treated with one to three passes of I1 watts and 2 dwelling time, 396 and 485 µsec are about 20-50 µm and 25-150 µm, respectively.

CONCLUSION: Every parameters in this study can be used for skin resurfacing. The recommended optimum parameters are the power setting of 11 watts and dwelling time of less than 485 µsec because they produced the least residual thermal necrosis. The recommended optimum parameters for maximum aesthetic effect can be use only one pass because the subsequent passes produced the constant ablation depth but increasing the depth of residual thermal necrosis and increasing the risk of scarring.