Sounds like Hollywood is up to its old tricks again!  There was a very short period of time several years ago when radiation therapists tried using ice packs before giving radiation.  The thought was that the ice would cool the body and perhaps decrease some of the side-effects of radiotherapy.  However, this was short-lived and never proven to work.  A thorough search of the medical literature and personal conversations with local radiation oncologists reveals no evidence that this practice of ice pre-treatment is currently being used.  It's just in the movies.

It is interesting to know that radiotherapists sometimes try the opposite.  Instead of using ice, radiation oncologists will use heat to warm the skin before giving radiation treatments!  The heat helps to kill certain types of cancer cells in combination with the radiation.  This is only used in very specific types of cancer.

Regardless of ice or heat, radiation is a very effective and important part of treatment for many cancers in adolescents and young adults.  Radiation works by creating something called "oxygen radicals."  These radicals are deadly to growing cancers.  Radiation sometimes will be used to treat Acute Lymphoblastic Leukemia (ALL), like in the movie you saw.  Radiation therapy is used before bone marrow transplants to help eliminate every last leukemia cell in the body and condition the body to receive the transplant (knock down the immune system so it doesn't reject the donor stem cells).  This type of pre-transplant radiation is called TBI, or Total Body Irradiation, because the entire body will be irradiated over several days in a row.  The other time radiotherapy is commonly used in leukemia is to radiate the brain when there are leukemia cells found in the central nervous system.  Radiation is also used in ALL when there is testicular disease.  Radiation therapy has been used for many years now, and is part of the reason the cures for ALL remain so high.