Uneven distribution of light in standard phototherapy.

Maldistribution of light is a potential cause of phototherapy failure in the neonate. Differences in light intensity over the surface can be measured with a radiometer as this detects the radiant energy impinging on the incubator mattress. An infant nursed on the front third of the mattress receives less than 40% of the maximal light incident on the centre of the mattress, and consequently degradation of unconjugated bilirubin will be less effective.