A survey of the ultraviolet radiation emissions of photochemotherapy units

Abstract

Measurements have been made of the spectral emission and irradiance from whole body ultraviolet irradiation units used in the treatment of psoriasis by photochemotherapy (PUVA). A total of ten units were studied, located at nine different treatment centres in England. The results showed that within the limits of experimental accuracy there was no significant difference in the profile of all spectra measured, although the measured value of irradiance compared with each centre's own UV-A meter showed wide discrepancies. There is poor documentation provided by manufacturers of UV-A meters on the meaning of the scale reading in mWcm-2, and it would seem expedient that some agreed calibration procedure for these instruments is forthcoming.

Morphology and Frequency of Heterochromatic Nuclear Sheets in Normal Circulating Human Leucocytes and after PUVA Therapy

“…The therapy regiment was in accordance with that reported by Wolff et a1 (1976) using Sylvania FR 90T12 lamps (Diffey et al 1980) and 8-methoxy psoralen capsules (Meladinin@, Nyco, Oslo). The lamps were tested before each treatment with a Waldmann PUVA meter (Diffey et al 1980) giving an exposure time of between 4 M O min to achieve dose of 10 J/cm2. The total UVA dosage for patient E.M. at the time of sampling was 80 J/cm2, for patient E.B.…”

Personal solar UV-A doses received by patients undergoing oral psoralen photochemotherapy for psoriasis

“…Both of these sources of exposure will contribute to the photocarcinogehic risk associated with the treatment. A recent survey (Diffey, Challoner & Key, 1980) ofthe performance of UV-A meters in clinical use has shown wide variations in accuracy, which may suggest that estimates of the 'known' dose of artificial UV-A may be suspect. It is generally recognized that the patient may be exposed to solar UV-A during a period when the drug is photoactive and, for this reason, the patient is advised to wear suitable UV-A protective glasses for the remainder of the day after ingestion of the psoralen to minimise the risk of cataract induction.…”

Frequency characteristics of a mode-locked solid-state ring laser with self-pumping waves

“…The absolute calibrations varied from a 70% overestimate of irradiance to a 20% underestimate Of irradiance. This large variation is not surprising in the light of a wider survey c a 9 d Out previously (Diffey et al 1980). The sensitivity of the meters can be readily a d N W by means of a potentiometer and so it is a simple matter to ensure a much variation in UVA meter response between Centres by regular calibration.…”