The Lodger - S5-E11
Continuity mistake: When the Doctor is flipping through a book while talking with Amy on his earpiece, in the close-up shot he's using his right hand, but in the wide shot is using his left hand, going through the pages the other way. (00:12:10)
Chosen answer: 1) When Stephen Moffat took over he ignored a lot of what had been developed before (there is not in-universe answer). 2) It would have killed Rose, so the Doctor absorbed the energy. His body regenerated before the energy could do a significant amount of damage that would prevent regeneration.