Probably dumb phototherapy question

[JohnB]

I notice tonight the boys rear end and lower back (areas that have never had sun exposure) are quite red and verging on burnt. We are due to go in for the third treatment of the week tomorrow. I will ask at the dermatologist office but I would appreciate your thoughts on a) do we wait until Monday and only go twice this week or b) go and ask for a lower dose snd less time so he is still getting the 3x uv but not getting a burn. It seems obvious to me to skip tomorrow, but I don’t want to lose and benefits (and time spent)

From my experience it all depends on whether it's uva or uvb. If it's the b version you shouldn't be burning. They normally carry on with the incremental time increases, but make you wear some dark clothing to cover the singed area. Occasionally they do stop it if you are burning where you really need the rays :s .
If it's uva then you will be taking tablets as well to make you more sensitive, this they push to the point of just turning pink it's where it is most efficacious.
UV treatment should really be closely monitored, it can do long term damage if you overindulge.