Feasibility and accuracy of a newly developed hand‐held device with a flat‐type fluorescent lamp for measuring the minimal erythema dose for narrow‐band UVB therapy

Abstract

Narrow-band ultraviolet B (NB-UVB) for the treatment of refractory skin diseases, such as psoriasis and atopic dermatitis, requires an adequate irradiation protocol based on the minimal erythema dose (MED) to establish an optimal dosage schedule. Although MED can be measured using a systemic-type irradiation unit, there are difficulties associated with this device. There is no standardized device available to determine the MED for NB-UVB. Here, we compared a conventional device with a newly developed device for measuring MED. MED was measured in 16 psoriasis patients using both a conventional measuring device and the newly developed device, which comprised a hand-held NB-UVB (311-313 nm) flat-type fluorescent lamp with neutral density filters having different transmittances ranging from 10% to 90%. This device was designed to be stably maintained on the skin surface and to provide a highly accurate measurement with only one UV irradiation exposure while also preventing UV radiation from leaking to nonirradiated areas. The MED values obtained from each patient were the same using both devices. One-time irradiation using the new hand-held device with the NB-UVB flat-type fluorescent lamp is feasible and accurate for determining the MED to use in calculating the UV irradiation treatment dose.