"I don't know. Twenty-three hours? Thirty-six? No more than thirty-six. And that's just until I can't hold back anymore. The amount of time before the effects of the radiation are irreversible ... " He shook his head. "It may be less. I've never tried to delay a regeneration like this before. There used to be rules for this sort of thing. There used to be Time Lords I could have asked for help."
He scrubbed his face with his hands, as though that would wash away the frustration and the hurt. "If I could just get the TARDIS close ... She doesn't have to dematerialize. If I could just ... " He broke off, then, eyes widening.
"Wait a minute. I have a phone. I have a phone. Donna, you're brilliant! The phone. Martha's phone. The one on the console. The cell phone. Hand it to me. Quick!"