I. What is photodynamic? Photodynamic therapy refers to the local application of photosensitizer, due to the different absorption and metabolic rate of human tissues, after a certain period of time, the photosensitizer will accumulate a higher concentration in the target tissue; after the light source irradiation of photodynamic, it will rapidly stimulate the photodynamic reaction and produce a large amount of monomorphic oxygen in the target tissue, and the cytotoxic effect of monomorphic oxygen will lead to the necrosis or apoptosis of the target tissue cells or affect the cell function, so that the lesion The cytotoxic effect of monomorphic oxygen will lead to necrosis or apoptosis of the target tissue cells or affect the cell function, so that the lesion will fall off, restore the normal form and function, while the adjacent normal tissue is not affected by a new treatment. Second, why is photodynamic therapy a convenient and effective treatment method? 1, generally do not need anesthesia, and less trauma, less pain; 2, good drug selectivity, high safety, significant curative effect; 3, high cure rate, fast recovery, low recurrence rate; 4, the operation is simple and convenient, can be carried out in the outpatient clinic or treatment room. Third, what is the treatment process of photodynamic? Routine local disinfection, dressing photosensitizer (topical amino ketovaleric acid hydrochloride dispersion) for 3 hours, local irradiation of lesions with photodynamic therapy system for 20-30 minutes, and topical antibiotics to prevent infection after treatment. IV. What are the indications for photodynamic therapy? At present, photodynamic therapy can treat warts, acne, etc. Of course, if combined with specific photosensitizers, it can also treat various skin tumors such as squamous cell carcinoma, basal cell carcinoma, Bowen’s disease, etc.; various viral skin diseases such as flat warts, plantar warts, Bowen-like papulosis, etc.; and solar keratosis, septic sweat glanditis, etc.