[Comparison of the minimal erythema dose for narrowband UV-B and broad spectrum UV-B using a new UV hand-held device].

BACKGROUND

Phototherapy requires an individually adapted therapeutic regime that is based upon the minimal erythema dose for each patient. Whereas this is well established for UV-B broadband, so far no standardized equipment existed that allowed for determination of the MED for UV-B 311 nm narrowband irradiation. Thus, the starting dose for UV-B 311 nm is usually adjusted to the clinical skin type or the MED for broad-spectrum UV-B irradiation.

PATIENTS AND

METHODS

We determined the MED for UV-B 311 nm in a cohort of 110 healthy test persons with a newly constructed hand-held UV-light source and compared it to UV-B broadband MED.

RESULTS

For UV-B broadband, the MEDs ranged from 46.2 to 210.9 mJ/cm(2) with an average value of 108.45 mJ/cm(2). For the MED of narrowband UV-B 311 nm, the values ranged from 300.9 to 1.386.0 mJ/cm(2) with an average value of 838.88 mJ/cm(2). Concerning the factor of the MED UV-B broad-spectrum related to MED UV-B 311 nm narrowband, values from 4.01 to 13.68 with a average value of 7.91 resulted. No significant differences could be detected for the MED of UV-B broad-spectrum and narrowband in correlation to age, sex or clinical skin type.

CONCLUSION

Our data emphasize the presence of extensive inter-individual differences in the MED of both UV-B-spectra and point to the necessity to test patients before the first irradiation.