Presently, many variations of light treatment are used in health care. Prime examples are the in-vivo or ex-vivo photodynamic treatment (PDT) of skin diseases, cancer/tumors, psoriasis, mood disorders, bladder infections, promoting wound closure, recovering spinal cord injuries, and countering muscle/bone atrophy. PDT is a treatment that uses a drug, called a photo-sensitizer or photosensitizing agent, and a particular type of light. The invention relates to an improved PDT device.