Didn't the rad onc clinic give her a handout on that? WE always did that.
wash with warm H20
preferably without soap
if you feel you have to use soap try dove/neutrogena
do not rub the area even though it may become red, dry, itchy
avoid tight clothes to the area
no lotions before any treatment
ask the rad onc RN/DR about applying aloe vera gel only after rad treatment
no heating pads or ice packs
avoid the sun/cover the area
be aware that for many years afterward if you go into the sun with that area
unprotected the spot may show up again and is more sensative to damage
If the skin gets bad they may put her on a rest break/and or prescribe some
Last but not least ask your Dr. (always the disclaimer)
Does that help?