A device for applying targeted phototherapy to an area of diseased skin to place a skin condition into remission and a method of determining a maximum tolerable dose of phototherapy applied to a treatment area of diseased skin to determine an optimum therapeutic dose to quickly place a skin condition into remission. The device can include a housing and an optical matrix arranged within the housing that are attached to a dosimetry device. The optical matrix includes a plurality of at least one of absorptive, reflective and/or partially transmissive regions or arrays of perforations that each permits a different percentage of light to be delivered to an individuals skin. Jigs can be included to arrange a plurality of varying exposures to be placed on the patients skin. An assessment can then be made as to the maximum tolerable dose of phototherapy that can be applied to the individuals skin in order to place a skin condition into remission.
