Content area
Full Text
Faced with pressure of work and limited resource, hospital doctors frequently use the nearest available light source, often a window, to examine and interpret patients' x -ray films. Arguably, diagnostic inaccuracies may result from such practice. Indeed it was recently suggested that daylight from a hospital window provides suboptimal illumination when compared with the light intensity from an x -ray viewing box. 1
The British Institute of Radiology guidelines quote values of 1500 to 3000 candelas as the ideal range of light intensity required to view and interpret x -rays. 2 The aim of this study was to examine the relative intensities of the light sources that are commonly available in hospitals, with which to view x -ray films, and to compare the intensities of these light sources with the light intensity levels recommended by the British Institute of Radiology.
METHODS
Light intensity was measured using a standard light meter (Profisix, Gossen Foot-un, Lichtmebtecnik, Nurnberg, Germany) at a constant 30 cm from the source. A control group of 10 individual x -ray viewing boxes (Wardray Premise Limited, Hampton Court Estate, Surrey, UK), each (four 18 watt bulbs) part of a bank of eight, present in the offices of 10 consultant radiologists, were compared with six other light sources (10 of each type) available on a district general hospital ward (Royal Gwent Hospital, Newport, South Wales, UK, longitude 3° west, latitude 51°35' north). The light sources were as follows: ward x -ray viewing boxes (H A West [X-ray] Limited, 41 Watson Crescent, Edinburgh, UK, four 18 watt bulbs), ward ceiling lights (36 watts...