Phototherapy units: Comparison of fluorescent ultraviolet B and ultraviolet A units with a high-pressure mercury system

Comparison in ultraviolet (UV) dosimetry is reported for three different phototherapy machines. Two of the machines used UV-emitting fluorescent tubes in a standard upright cabinet formation. One of these machines was equipped with predominately UVB-emitting fluorescent tubes and the other with predominately UVA-emitting tubes. The third machine consisted of a series of vertically mounted high-pressure mercury halide lamps equipped with two different filters for selection of wavelengths between 295 and 400 nm or 320 and 400 nm. The horizontal UV output of the mercury halide and UVB fluorescent units was reduced between the UV-emitting areas, and it is advised that patients rotate when using these units. It was determined that the vertical uniformity and intensity of UV emission was superior in the mercury halide unit compared with the fluorescent tubed units.