The salivary glands can swell during radiation, this can start about the fourth week as the cumulative dose approaches (or exceeds) that which causes tissue damage in the gland. My husband's right parotid gland swelled at about this time -- it was visually noticable if you looked hard -- and it was also somewhat tender. His RO said this was common. The swelling went down as radiation continued.

However what others have posted is correct, you need to have your doctor look at this and determine what is going on.

Gail