دانلود کتاب فتوفیزیک و نانوفیزیک در درمان

Phototherapy can be broadly defined as the use of photons for the treatment of diseases without the addition of an exogenous photosensitizer. Ultraviolet B (UVB) radiations (280–320 nm) are the most biologically active radiation in sunlight and are mainly responsible for erythema. The term “phototherapy” was used as a synonym for UVB radia­tion in the management of psoriasis. Phototherapy has wide clinical applications like pityriasis lichenoides, vitiligo, atopic eczema, polymorphous light eruption, pruritus, etc. (Morison, 1993

). Recent work in phototherapy explores the selective use of UV with a narrow wavelength centered on 311 ± 1 nm. It has been proven more effective and less ery­themogenic than conventional broadband phototherapy (Larkö, 1989). Treatments are usually given three to five times a week. The most widely used initial dose is 70% of the predetermined minimal erythema dose (MED) (Green et al., 1988). Treatment is continued until the condition is resolved (Wainwright et al., 1998). Selective UV phototherapy is the treatment of choice in children, which was used in the various study. The short-term side effects of phototherapy are usually mild and consist of xerosis and erythema, partly due to occasional overexposure. Another risk can be the pho­toactivation of herpes-virus. Long-term side effects of UVB phototherapy include premature photoaging and carcino­genesis with an increased incidence of wrinkling, actinic keratoses, lentigines, telangiectasia, and basal, and squamous cell carcinomas (De Gruijl, 1986). Radiation received from UVB phototherapy is cumulative with chronic sunlight exposure. UVB in combination with UVA phototherapy (UVAB) has been shown to produce better therapeutic suc­cess than UVB per se in treating mild to moderate atopic dermatitis (Falk, 1985; Hannuksela et al., 1985; Pašić et al., 2003). Phototherapy uses UV radiation or visible light for the treatment of different diseases by the exposure of small, well-defined anatomical areas to non-ionizing radiations using dichromic lamps, fluorescent lamps, light-emitting diodes, lasers, polychromatic polarized light, or very bright, full-spectrum light for therapeutic advantages. The origin of phototherapy can be traced back to 1500 BC, when Hindus treated vitiligo, an autoimmune skin disorder, with pho­tosensitizing plant extracts and subsequent sunlight exposure. For many centuries only natural sunlight (heliotherapy) was used to treat different skin conditions. Interestingly, it is still highly popular for psoriasis and atopic dermatitis in many geographic areas in the world, especially in the Dead Sea region (Matos et al., 2016).