Phototherapy and Photochemotherapy

Human diseases have been treated with the sun's rays since antiquity. 1 It is a form of phototherapy, which is defined as the direct use of nonionizing radiation to treat disease. The use of ultraviolet B radiation (290 to 320 nm) in the treatment of psoriasis, with or without the additive effect of coal-tar products, is an excellent example of phototherapy. The effects of ultraviolet B rays on this disease appear to result from a direct inhibition of DNA synthesis and mitosis in the hyperproliferating epidermal cells that are characteristic of psoriasis. 2 However, direct effects on dermal blood vessels and infiltrating . . .