Although both flashlamp-pumped pulsed dye laser and vascular-targeted photodynamic therapy have demonstrated safety and efficacy for port wine stains (PWS), the clinical results of these methods may be limited because the laser parameters used are virtually identical for all PWS patients despite their variations from site to site. A method that combines digital color-image processing with clustering segmentation based on color similarity and spatial proximity is proposed to refine the severity grading of PWS lesions. The evaluation in the color spaces of CIE-L*a*b*, value of a*, and erythema index are analyzed and compared, and the severity level grading is refined with the reference of a 10-level red color bar. The proposed clustering method can be used as a detailed objective assessment for PWS with a low-cost camera.
Planning of irradiance distribution (PID) is one of the foremost factors for on-demand treatment of port wine stains (PWS) with photodynamic therapy (PDT). A weighted optimization method for PID was proposed according to the grading of PWS with a three dimensional digital illumination instrument. Firstly, the point clouds of lesions were filtered to remove the error or redundant points, the triangulation was carried out and the lesion was divided into small triangular patches. Secondly, the parameters such as area, normal vector and orthocenter for optimization of each triangular patch were calculated, and the weighted coefficients were determined by the erythema indexes and areas of patches. Then, the optimization initial point was calculated based on the normal vectors and orthocenters to optimize the light direction. In the end, the irradiation can be optimized according to cosine values of irradiance angles and weighted coefficients. Comparing the irradiance distribution before and after optimization, the proposed weighted optimization method can make the irradiance distribution match better with the characteristics of lesions, and has the potential to improve the therapeutic efficacy.
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