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Fok et al. Skin temperature of laser for Nevus of Ota

and will result in the prediction of skin temperature of photodermatoses or skin cancer; (4) concurrent
distribution and the study of skin burn injury -- important use of known photosensitizing drugs; and (5) any
issues in laser treatment. [23] However, more information therapy within the previous 2 months to the proposed
on the thermal response and temperature distribution oculodermal melanosis test sites.
during laser treatment is needed to avoid permanent
complications. For the infrared thermal imaging study, 5 QSRL test
sites were prospectively identified on each patient
Differential scanning calorimeters have been used to for treatment assignment according to the following
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evaluate the surface heat flux, temperature, and heat parameters: 6, 7, 8, 9, and 10 J/cm . Laser energy
absorption rate at the skin surface. An infrared thermal was delivered to the skin through an optical fiber and
imaging device was used in this study to measure skin lens that focused the beam onto a 3 mm spot on the
temperature in laser skin surgery. The main objectives lesion. The untreated area was assigned as a control.
of this study focus on the analysis and evaluation Sites were assigned to one-treatment regimens by
of skin temperature during laser application. This randomization. Every effort was made to place the
will in turn, assist medical practitioners in assessing test sites on optically uniform areas of the lesion to
and treating the reaction of skin to laser energy and ensure that clinically relevant oculodermal melanosis
avoiding complications. [24] A heat transfer analysis characteristics and geometry (i.e. epidermal melanin
using the thermal wave equation helps us to learn the concentration and depth) did not substantially vary
importance of the thermal wave theory of photothermal between each of the test sites on an individual patient
effects. Using an infrared thermal image instrument basis. Photographs were taken of the test sites after
and with the thermal changes obtained using a thermal treatment regimen assignment and at follow-up visits.
wave equation, the reliability of the analytic solution
will be ensured. Further discussion of the QSRL used The imaging and changes of skin temperature were
in cutaneous laser surgery is presented to provide measured in real time using an infrared thermal image
knowledge of the temperature changes of patients’ instrument (ThermaCAM™S60, FLIR System, Danderyd,
skin during laser treatment. With this, more accurate Sweden). The results of temperature distributions related
predictions of skin surface temperature can be to the energy variance were analyzed. Data of the skin
achieved which could serve as treatment references surface temperatures measured by the infrared thermal
for researchers and clinicians. image instrument was put into the analytic solutions
of the thermal wave equation with comparisons made
[26]
METHODS between the results. The clearing and fading result of
pigmentation was assessed by a DermoSpectrometer
From January 2010 to June 2012, 40 patients with (Cortex Tech., Hadsund, Denmark) to calculate the
oculodermal melanosis treated with the 694 nm QSRL melanin-index at follow-up visits for each of the test site
(Derma-Laser, Hopkinton, MA, USA) at the settings of treatment regimens. [27-29]
25 ns pulse duration, energy densities of 6-10 J/cm , with
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a spot size of 3 mm were observed in this retrospective The device emits light from diode sources at two defined
study. The age range was 18 to 54 years, with a mean wavelengths. The amount of light backscattered from
of 28 years. There were 25 females and 15 males. the skin is then used to determine the indices for
Based on pretreatment photographs, each oculodermal hemoglobin/melanin. Therefore, care was taken to
melanosis was assigned a severity grade using the make each measure with the device in contact with
Tanino classification system. [25] Patients were grouped the skin, but without the application of pressure to the
into four different clinical types: (1) mild; (2) moderate; (3) test site. The melanin index for pre-treated lesions,
intensive; and (4) bilateral. Observation was analyzed along with those of treated oculodermal melanosis,
based on the following variables: age, gender, severity, was also measured. The patients were observed after
number of treatment(s), duration of treatment(s), and treatment(s), and those calculations were used to
improvement following laser therapy. The study protocol display a better correlation with how the oculodermal
was approved by the Institutional Review Board at melanosis differed from the initial pre-treated lesion
Chang Gung Memorial Hospital. Inclusion criteria for calculations. Differences between the responses
the study was: (1) oculodermal melanosis suitable of each site before and after QSRL treatment were
for comparison testing; (2) oculodermal melanosis then determined and analyzed. Patients were also
greater than 20 cm ; and (3) apparent good health as closely monitored for any adverse effects. Each of
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documented by medical history. The following exclusion the test sites was examined for unfavourable wound
criteria was determined as: (1) inability to commit to a characteristics such as blistering, scabbing, erosion
three month follow-up period; (2) pregnancy; (3) history and scarring. The primary measure of efficacy was
Plastic and Aesthetic Research ¦ Volume 4 ¦ January 19, 2017 3