Photodynamic Therapy or PDT is a method of treatment where a chemical called Aminolevulinic acid (ALA) is applied to the skin and then activated with a light source. Sometimes this light source is a laser, sometimes it is an IPL, and sometimes it is a panel of high intensity blue lights. They all work, even the sun can activate the chemical (that is why you must avoid the sun after treatment).
PDT is used to treat acne, sun damage, and pre-cancerous lesions called actinic keratoses. It...