A new method of phototesting before narrowband UVB therapy.

Narrowband UVB therapy is versatile and generally preferred to broadband sources. Recently, a convenient device has been described which gives 10 different doses simultaneously to the forearm to determine the minimal erythema dose (MED). It is known there is no relation between sun reactive skin type and MED. Twenty-four individuals were tested using 26% increments giving a range of MED of between 0.38 J/cm2 and over 1.5 J/cm2. When compared to conventional window testing in 15 cases, it was found to be identical or within one increment.