INTRODUCTION
Psoriasis is a chronic, immune-mediated disease with prevalence estimates within adult populations ranging from 0.91% in the USA to 8.5% in Norway.1 The disease mainly affects the skin and joints and has several phenotypes, of which the most common is psoriasis vulgaris (plaque-type psoriasis).2 Psoriasis vulgaris typically presents as well-defined, symmetric, erythematous scaly plaques on the scalp, trunk, nails, and extremities. Symptoms include itching, burning and soreness.3
The treatment approach for psoriasis depends on disease severity (defined by the percentage of affected body surface area), involved body areas, comorbidities, age, patient preference (including cost and convenience), and individual patient response to therapy.3,4 Limited psoriasis can often be managed with topical agents, while patients with moderate to severe disease may also need phototherapy by ultraviolet irradiation or systemic therapy.5 During phototherapy treatments, therapeutic doses of ultraviolet light may be administered by broadband ultraviolet B (UVB) radiation (290-320 nm), narrowband UVB (311-313 nm), and PUVA - photochemotherapy with psoralen followed by ultraviolet A radiation (320-400 nm).6,7
In targeted phototherapy, a high-energy 308 nm excimer laser delivers ultra-narrowband-UVB directly to the psoriasis plaque with minimal exposure of healthy skin to UVB radiation. Due to the targeted nature of the excimer laser, considerably higher doses of UVB can be administered at each treatment session when compared with traditional phototherapy since dosing is not limited by the lower light tolerance of healthy skin.8
Dosimetry for phototherapy with the excimer laser has been traditionally determined either through the induration protocol, which takes into account the patient’s Fitzpatrick skin type and the degree of plaque induration,9 or through the minimal
The treatment approach for psoriasis depends on disease severity (defined by the percentage of affected body surface area), involved body areas, comorbidities, age, patient preference (including cost and convenience), and individual patient response to therapy.3,4 Limited psoriasis can often be managed with topical agents, while patients with moderate to severe disease may also need phototherapy by ultraviolet irradiation or systemic therapy.5 During phototherapy treatments, therapeutic doses of ultraviolet light may be administered by broadband ultraviolet B (UVB) radiation (290-320 nm), narrowband UVB (311-313 nm), and PUVA - photochemotherapy with psoralen followed by ultraviolet A radiation (320-400 nm).6,7
In targeted phototherapy, a high-energy 308 nm excimer laser delivers ultra-narrowband-UVB directly to the psoriasis plaque with minimal exposure of healthy skin to UVB radiation. Due to the targeted nature of the excimer laser, considerably higher doses of UVB can be administered at each treatment session when compared with traditional phototherapy since dosing is not limited by the lower light tolerance of healthy skin.8
Dosimetry for phototherapy with the excimer laser has been traditionally determined either through the induration protocol, which takes into account the patient’s Fitzpatrick skin type and the degree of plaque induration,9 or through the minimal
