I am trying to work out radiation intensity at points along a transect with an increasing distance from the source. Despite having virtually no high school maths, I understand that by applying the inverse-square law (I = P / 4[itex]\pi[/itex]r2) to points < 1m from my radiation source is going to give readings which are higher than the intensity of the emitting object, and therefore false. The embarrassing part is that a) I don't fully understand WHY this is the case and b) I'm not sure how to correct for it. I still need to calculate the radiation intensity at 0.1, 0.25, 0.5 and 0.75m away from the target source. Is there a simple way of correcting it? This may seem obvious to everyone else, but unfortunately not to me.