You mother will get through it. But do let her know that she has to keep up with her fluid intake and put cream on her face and neck are (NOT before radiation, but immediately after radiation). My husband had a few double sessions during his treatment because of the Christmas holidays. It was a bit of a drag because we had to go to the hospital twice in a day, but it did not seem to make a significant difference to how he was feeling.

Gloria
She stood in the storm, and when the wind did not blow her way, she adjusted her sails... Elizabeth Edwards

Wife to John,dx 10/2012, BOT, HPV+, T3N2MO, RAD 70 gy,Cisplatinx2 , PEG in Dec 6, 2012, dx dvt in both legs after second chemo session, Apr 03/13 NED, July 2013 met to lungs, Phase 1 immunotherapy trial Jan 18/14 to July/14. Taxol/carboplatin July/14. Esophagus re-opened Oct 14. PEG out April 8, 2015. Phase 2 trial of Selinexor April to July 2015. At peace Jan 15, 2016.