Characterisation of Ultraviolet (Uv) Therapy Machine (Phototherapy)

Abstract

Ultraviolet radiation therapy machine as applied in dermatology treatment has been characterised using Microsoft Excel and Surfer 8 software. The irradiance of the device was measured in both 2-dimensions and 3-dimensions. The average temperature recorded during the measurements was 210±10C. The highest irradiance measured on the 200L device was 10.00 ± 0.31 mW/cm2, and the lowest was 5.00 ± 0.44 mW/cm2. On the 180L device, the highest was 6.00 ± 0.40 mW/cm2 and the lowest was 3.00 ± 0.57 mW/cm2. The radiation intensities varied across the surface of the device with the highest values measured on top of the lamps while the lowest values were measured between the lamps. Both surface and contour maps were constructed to interpret the data, and significant variations of the intensities were observed. The results indicate that dirt on lamps, and aging lamps show varying irradiances along each tube, with the potential causes of erythema and burns on the hands and feet of patients. This suggests that, instead of using the average irradiance, of a couple of readings on the panel, as the mean dose for treatment, the maximum dose recorded should be used instead, and where the tolerance of the measured irradiance is ±10% along a tube, and, or among the tubes, the defected tube or the whole set of tubes should be replaced with new ones. Regular checks on UV lamps should be encouraged, as per local rules and the manufacturer’s manual, to avoid erythema and patient discomfort.