Three-dimensional illumination procedure for photodynamic therapy of dermatology

Abstract

Abstract. Light dosimetry is an important parameter that affects the efficacy of photodynamic therapy (PDT). However, the irregular morphologies of lesions complicate lesion segmentation and light irradiance adjustment. Therefore, this study developed an illumination demo system comprising a camera, a digital projector, and a computing unit to solve these problems. A three-dimensional model of a lesion was reconstructed using the developed system. Hierarchical segmentation was achieved with the superpixel algorithm. The expected light dosimetry on the targeted lesion was achieved with the proposed illumination procedure. Accurate control and optimization of light delivery can improve the efficacy of PDT.

Optimization of irradiance for photodynamic therapy of port-wine stain

“…A treatment system consisting of a binocular vision system and an image progress unit was used for three-dimensional (3-D) reconstruction of lesion areas; this reconstructed model will serve as the objective basis to optimize the direction of the irradiation treatment. 24,25 As shown in Fig. 1(a), the proposed model for binocular digital illumination comprised a camera, digital projector, and computing unit.…”

“…Digital color images of the skin were used to segment the lesions, and 3-D lesion coordinates were indexed from the two-dimensional projector image. 24,25 Although previous studies specified that the point clouds obtained using structured light measurements with MeshLab exhibited high reconstructive accuracy, 24 error points may still exist because of incorrect lesion extraction. Processing the point clouds and calculating the characteristic parameters of the lesion surface are important in optimization to accurately characterize the surface features of lesions.…”

“…( 14) without considering the optical parameters of the lesion tissue. 24 p ¼ EHWβ 2 cos θðcos γÞ 4 η :…”

“…The areas with different colors in the head model can be separately clustered via a superpixel method. 24 The severity of lesions in a patch can also be considered as another weight coefficient in the proposed optimization function. Severely affected regions can receive increased irradiance when the irradiation distribution is improved in the optimized direction within a specific power.…”

“…21 Additional parameters must be established to accurately control illumination and develop individualized single treatment plans, thus reducing the incidence of adverse effects and improving the efficacy of PDT for treatment of PWS. [21][22][23][24][25] Precise control of the light dose is dependent on the performance of a control system rather than subjective experiences and assessments. So an intelligent irradiation system with a large coverage and flexible conformity should be designed to increase the reliability and consistency of PDT.…”