Determination of minimal erythemal dose for narrow band-ultraviolet B radiation in north Indian patients: comparison of visual and Dermaspectrometer readings.
BACKGROUND
Minimal erythemal dose (MED) for narrow band-ultraviolet B radiation (NB-UVB) varies with race and skin type. The aim was to estimate the MED for NB-UVB and compare visual readings with those from a Dermaspectrometer in a north Indian patients as the available data is sparse.


METHODS
Forty one patients who visited the dermatology outpatient department were recruited for this study. Skin type was grouped as per Fitzpatrick skin type scale. Patients' upper backs were irradiated after applying a novel template with 8 windows of 2 x 2 cm each, with a test dose ladder of 250-1500 mJ/cm2 in a Waldmann (700K) TL-01 chamber. MED and erythema index were read after 24 hours, the latter by using Dermaspectrometer.


RESULTS
Forty one patients (10 males, 31 females) with mean age of 30.5 (14-65) years were recruited. 23 patients were of skin type 5, 17 of type 4 and one of skin type 3. The estimated MEDs were 1000 mJ/cm2 in 17, 750 mJ/cm2 in 19, 1100 mJ/cm2 in four and 500 mJ/cm2 in one patient. The median and mode MED was 1000 mJ/cm2. There was an exponential rise in the erythema index with increase in irradiation (17.18-26.25/250-1500 mJ/cm2). Student's t-test applied to detect differences between the visual and Dermaspectrometer readings was found to be statistically not significant.


CONCLUSIONS
The estimated MED for NB-UVB varied from 500 to 1100 mJ/cm2, the median MED being 1000 mJ/cm2. The darker skin types did not have low MED while some patients with lighter skin type displayed lower MED. There was no significant difference in MED determined by visual and Dermaspectrometer readings.
Tejasvi
Trilokraj
T
Department of Dermatology and Venereology, All India Institute of Medical Sciences, New Delhi, India.
Sharma
Vinod K
VK
Kaur
Jasleen
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D004890:Erythema / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D012867:Skin / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*