Photosensitizers can dynamically concentrate in abnormal growth tissues (e.g., tumors, age-related macular degeneration, macular nevus, acanthosis, etc.), and they can produce reactive oxygen species such as singlet oxygen under the excitation of appropriate wavelengths of light, which can destroy target cells. The development and application of PDT were gradually improved with the development of photosensitizer research. The advantages of photodynamic therapy are different from the three traditional treatments of surgery, radiotherapy and chemotherapy in that it is selective to the target tissue and the degree of damage, and can reduce the damage to normal tissues. Compared with the conventional treatments such as surgery, chemotherapy and radiotherapy, photodynamic therapy has the following important advantages: 1. minimal trauma: with the help of fiber optics, endoscope and other interventional techniques, laser can be guided deep into the body for treatment, avoiding the trauma and pain caused by open-chest and open-abdomen surgeries. 2. 2.Low toxicity: The photosensitive drug entering the tissue will trigger photodynamic reaction and kill tumor cells only when it reaches a certain concentration and is irradiated by sufficient amount of light, which is a local treatment method. The part of human body that is not irradiated by light does not produce such reaction, and the organs and tissues in other parts of human body are not damaged, nor does it affect the hematopoietic function, so the toxic side effects of photodynamic therapy are very low. 3, selective good: photodynamic therapy is the main target of the light irradiation area of the lesion tissue, the normal tissue around the lesion damage is slight, this selective killing effect is difficult to achieve many other treatment means. 4.Good applicability: Photodynamic therapy is effective for different cell types of cancer tissues and has a wide range of applicability; while the sensitivity of different cell types of cancer tissues to radiotherapy and chemotherapy can vary greatly and the application is restricted. 5.Repeatable treatment: Cancer cells are not resistant to photosensitive drugs, and patients will not increase toxic reactions due to multiple photodynamic treatments, so treatment can be repeated. 6.Can be palliative treatment: For patients with advanced tumor, or tumor patients who cannot receive surgery due to advanced age, cardiopulmonary, hepatic and renal insufficiency and hemophilia, photodynamic therapy is a palliative treatment that can effectively relieve pain, improve quality of life and prolong life. 7.It can improve the efficacy in cooperation with surgery: for some tumors, surgical resection is performed first, and then photodynamic therapy is administered, which can further destroy the residual cancer cells, reduce the chance of recurrence and improve the thoroughness of surgery; for some other tumors, it is possible to do photodynamic therapy first to make the tumor shrink before resection, which can expand the indications for surgery and improve the success rate of surgery. 8.It can eliminate the hidden cancer lesions: clinically, some tumors, such as bladder metastatic cell carcinoma, may have scattered tiny cancer nests invisible to the naked eye outside the main lesion, conventional treatment can only remove the main lesion and can do nothing about the hidden cancer nests, but with photodynamic therapy, it takes the method of surface irradiation after the whole bladder is filled to eliminate all the tiny lesions that may exist, thus greatly reducing the chance of tumor recurrence. 9.Protecting appearance and important organ functions: For skin cancer of face, oral cancer, penile cancer, cervical cancer, retinoblastoma, etc., the application of photodynamic therapy may effectively kill cancer tissues while minimizing damage to epithelial structure and collagen scaffold of the organ of pathogenesis, so that the appearance will be less affected after the wound heals and the organ shape and normal physiological functions will be kept intact. The application of photodynamic therapy is very promising. In recent years, great progress has been made at home and abroad in the application of photodynamic therapy for the treatment of non-tumor diseases, such as acanthosis, nevus, fundus macular degeneration, rheumatoid arthritis, psoriasis, atherosclerotic plaques, and post-angioplasty restenosis. In particular, the new topical photosensitizer’s – Aminoketovaleric Acid Hydrochloride (Aila, ALA) was marketed and creatively used for the treatment of acromegaly, pushing the photodynamic treatment of acromegaly with Aminoketovaleric Acid Hydrochloride to clinical research for the first time in the international arena. The results of clinical trials showed that ALA-photodynamic therapy for intra-urethral warts had a 95% wart clearance rate and was well tolerated by patients; for extra-urethral warts, the wart clearance rate was 98.42%. The recurrence rate is only 10.77%. At the same time, the safety is high: no scars, the incidence of adverse reactions is only 7.67%. Experts agree that Ira photodynamic therapy will become the first choice for intra-urethral warts and the first line of treatment for extra-urethral warts. The process of photodynamic therapy is simple, the main operational steps are the application of medicine and light, and the treatment process is painless: 1, first by the medical staff to configure fresh medicine, to be used during treatment. 2, with fresh liquid wet dressing of the affected area for 3 hours, and depending on the specific situation for sealing. 3, photodynamic irradiation of the lesion local, irradiation time is usually 20 minutes. 4. When the course of treatment is over the warts become flaky and dry and fall off on their own. The Urethral Warts ALA-PDT treatment before and after, who is suitable to receive photodynamic therapy? 1, special anatomical site treatment: such as warts occurring in the urethral orifice, urethra, vulva around the opening of the glands of patients. 2, sensitive parts of the treatment: such as warts occurring in the mucous membrane parts of the patient. 3. Patients who have relapsed after trying other treatments. 4. Patients who are being treated for the first time. 5. Patients with single or small number of warts, i.e. patients with concentrated latent lesions. 6, after the treatment of other traditional therapies to consolidate the effect of treatment to prevent the recurrence of warts.