Phototherapy methods and systems

Abstract

The invention features methods and systems for treating inflammatory, proliferative skin disorders such as psoriasis, with ultraviolet phototherapy. The methods and systems use optical techniques to scan a patient's skin, designate areas of affected skin, and selectively deliver high doses of phototherapeutic ultraviolet radiation to the designated areas. To insure that only affected areas of skin affected are designated for the high doses of UV radiation, the methods and systems use one or more optical diagnostics that relate to independent physiological features of affected skin.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from provisional application 60 / 061,487, filed Oct. 8, 1997, the contents of which are incorporated herein by reference.FIELD OF THE INVENTION [0002] This invention relates to treatment of psoriasis and other proliferative skin disorders using phototherapeutic techniques. BACKGROUND OF THE INVENTION [0003] Psoriasis is a chronic, incurable, inflammatory skin condition affecting two to four percent of the world's population. Severity ranges from minor to life-threatening, and often fluctuates. Pathogenesis is unknown, but involves hereditary abnormalities of the immune system, with lymphocyte and neutrophil-mediated inflammation combined with hyperplasia of the epidermis. The epidermis proliferates at about ten times the normal rate. People with psoriasis literally leave a trail of skin flakes, and suffer from chronic itchy lesions, poor temperature regulation, fatigue from constant protein loss, and soci...

AI Technical Summary

Benefits of technology

[0024] Embodiments of the invention include many advantages. For example, the methods and systems selectively deliver radiation to only those areas of skin affected by psoriasis, thereby reducing risks such as sunburn (acute risk) and skin cancer (chronic risk), which are inherent in present phototherapy methods. For example, scrotal cancer is about 200 times higher in patients subject to present phototherapy methods.

[0025] Furthermore, the methods and systems allow large doses of radiation to be delivered to the affected areas, which increases the effectiveness of the phototherapy. Furthermore, for these affected areas, skin cancer risk is reduced since only a few high-dose radiation treatments are used in place of many low-dose radiation treatments. Epidemiologic studies suggest that skin cancer risk is lower when a higher dose-per-treatment and lower cumulative dose is used.

[0026] Also, the methods and systems greatly reduce the number of treatments necessary to clear the psoriasis, from about 25 to about 5 to 10. The cost of psoriasis phototherapy is dominated by the number of treatments needed for clearing. As a result, in the United States, for example, the invention could save over one half of the annual phototherapy cost of about one billion dollars. The methods and systems also reduce the space and time required for each individual treatment, further reducing phototherapy costs. For example, since only affected areas are being treated, a doctor need not need be concerned about sunburning unaffected skin. Thus, before each treatment, the doctor need not determine the amount of radiation corresponding to one MED, as in traditional phototherapy.

Problems solved by technology

These dose levels are very effective at treating affected areas of skin, but would badly damage unaffected areas of skin, e.g., normal skin.

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