What is Photodynamic Therapy? Photodynamic Therapy (PDT) is a new technology that uses the photodynamic effect for diagnosis and treatment of diseases. Its action is based on the photodynamic effect. It is a photosensitization reaction with biological effects involving oxygen molecules. The process is that laser irradiation at a specific wavelength excites the photosensitizer absorbed by the tissue, and the excited state of the photosensitizer transfers energy to the surrounding oxygen, generating highly reactive monomorphic oxygen, which reacts with adjacent biological macromolecules to produce cytotoxic effects, leading to cell damage or even death. Does the patient feel pain during photodynamic therapy? The destruction of lesions caused by photodynamic therapy is quite gentle, and the physical and chemical stimulation of painful nerves is minimal, generally speaking only mildly uncomfortable. However, in order to minimize the patient’s nervousness and make the treatment go more smoothly, the doctor will still use sedation or take necessary anesthesia measures as appropriate, so the patient should not worry about this at all. Why is laser used for photodynamic therapy? In photodynamic therapy, the photosensitive drug must be activated by a specific wavelength of light in order to trigger the photodynamic effect to kill the tumor. This specific wavelength of light must be strong enough and can be efficiently transmitted through fiber optics to be directed to the internal cavity to irradiate the tumor in a wide range. Usually, in clinical work, only the light from the corresponding laser can meet the above requirements. What is meant by photosensitizer? In photochemical reactions, there is a class of molecules that only absorb photons and transfer energy to those molecules that cannot absorb photons to induce a chemical reaction, while they themselves do not participate in the chemical reaction and return to their original state, which are called photosensitizers. The photochemical reaction triggered by the photosensitizer is called the photosensitive reaction. Usually, people call the photosensitive reaction with oxygen molecules participating in the accompanying biological effect a photodynamic reaction, and drugs that can trigger a photodynamic reaction to destroy cell structures are called photodynamic drugs, i.e. photosensitizing drugs. Applicable diseases In addition to various types of tumors, they can also be used for non-tumor diseases in dermatology, such as warts, psoriasis, keloids, acne, naevus, etc. It is safe and low toxicity, protects the patient’s appearance, no obvious painful feeling, the disadvantage is that it is only suitable for small area, localized patients, and more expensive.