A Pilot Research On SFDI-based Method For In Vivo Evaluation Of Photodynamic Therapy Of Non-melanoma Skin Cancer

Non-melanoma skin cancer is a common malignant skin cancer disease.Photodynamic therapy(PDT),as a new treatment for non-melanoma skin cancer,has been attracted much attention in recent years.However,a real-time,noninvasive and in vivo evaluation method is still need to be determined,for the therapeutic effects varies from person to person.In clinical,the critical factor to determine the curative effect of PDT is whether the yield and accumulation of toxic singlet oxygens(TSO)during treatment time in lesion tissue can be met.Based on this,a noninvasive and in vivo evaluation model of PDT efficacy is discussed here focusing on the solution of yield and accumulation of TSO.To solve the model,both the distribution of light dose and the photo sensitizer dose in vivo are the premise.Therefore,a single-pixel spatial frequency domain imaging(SFDI)system based on lock-in photon-counting detection is developed firstly for obtaining the raw data of distribution information of optical parameters and the fluorescence yield in real-time for the solution of the light dose and the photo sensitizer dose under the tissue.System validation results show that the developed SFDI system realizes the parallel signal acquisition used for reconstruction of optical parameters and fluorescence yield.Then,a pilot and simulated exploration for the developed accurate evaluation model of PDT efficacy focusing on TSO yield is made here,which is based on the predefined normal and cancerous skin tissue optical model and initial values of photo sensitizers commonly used clinically.Firstly,a perturbation and mesh based Monte-Carlo method is used to solve the light dose distribution under the cancer skin model using the information of optical parameters.In this way,the efficiency of light dose evaluation is improved and the requirement of computing power is reduced compared with traditional MC method.Later,according to the distribution of the light dose and initial values of photo sensitizer,the photosensitizer dose,the normal oxygen dose,the yield,productivity and accumulation of TSO at different times in the model are all be determined successfully.