Bäumler Wolfgang, Vural Emre, Landthaler Michael, Muzzi Francesco, Shafirstein Gal
Department of Dermatology, University of Regensburg, Regensburg, Germany.
Lasers Surg Med. 2007 Feb;39(2):132-9. doi: 10.1002/lsm.20408.
Intense pulsed light (IPL) sources have been successfully used for coagulation of blood vessels in clinical practice. However, the broadband emission of IPL hampers the clinical evaluation of optimal light parameters. We describe a mathematical model in order to visualize the thermal effects of IPL on skin vessels, which was not available, so far.
STUDY DESIGN/MATERIALS AND METHODS: One IPL spectrum was shifted towards the near infrared range (near IR shifted spectrum: NIRSS) and the other was heavily shifted toward the visible range (visible shifted spectrum: VSS). The broadband emission was separated in distinct wavelengths with the respective relative light intensity. For each wavelength, the light and heat diffusion equations were simultaneously solved with the finite element method. The thermal effects of all wavelengths at the given radiant exposure (15 or 30 J/cm2) were added and the temperature in the vessels of varying diameters (60, 150, 300, 500 microm) was calculated for the entire pulse duration of 30 milliseconds.
VSS and NIRSS both provided homogeneous heating in the entire vessel. With the exception of the small vessels (60 microm), which showed only a moderate temperature increase, all vessels exhibited a temperature raise within the vessel sufficient for coagulation with each IPL parameter. The time interval for effective temperature raise in larger vessels (diameter >60 microm) was clearly shorter than the pulse duration. In most instances, the vessel temperature was higher for VSS when compared to NIRSS.
We presented a mathematical model capable of calculating the photon distribution and the thermal effects of the broadband IPL emission within cutaneous blood vessels.
强脉冲光（IPL）光源已在临床实践中成功用于血管凝固。然而，IPL的宽带发射阻碍了最佳光参数的临床评估。我们描述了一个数学模型，以便可视化IPL对皮肤血管的热效应，而这一模型目前尚不存在。
研究设计/材料与方法：一种IPL光谱向近红外范围偏移（近红外偏移光谱：NIRSS），另一种则向可见光范围大幅偏移（可见光偏移光谱：VSS）。宽带发射被分离为具有各自相对光强的不同波长。对于每个波长，使用有限元法同时求解光和热扩散方程。将给定辐射暴露（15或30 J/cm²）下所有波长的热效应相加，并计算在30毫秒的整个脉冲持续时间内不同直径（60、150、300、500微米）血管中的温度。
VSS和NIRSS在整个血管中均提供均匀加热。除了小血管（60微米）仅显示适度的温度升高外，所有血管在每个IPL参数下血管内的温度升高均足以实现凝固。较大血管（直径>60微米）有效升温的时间间隔明显短于脉冲持续时间。在大多数情况下，与NIRSS相比，VSS时血管温度更高。
我们提出了一个能够计算光子分布以及宽带IPL发射在皮肤血管内热效应的数学模型。
