External beam radiation therapy uses high-energy photons delivered by a linear accelerator. The radiation treatment sessions are short and are given on weekdays for up to 9 weeks. When used together with brachytherapy, the external beam sessions are for 5 weeks. The treatment itself is painless and lasts only several minutes per day.
A new technique called Intensity Modulated radiation therapy (IMRT) delivers higher doses of radiation than conventional external radiation without contributing to added toxicity. Data from this technique of delivering radiation is early, but shows improved cancer control as compared to the conventional doses.
Side effects from external beam radiation may include fatigue, skin reaction in the treatment area, frequent and/or uncomfortable urination, a change in bowel habits and rectal irritation. Most of these side effects will improve after the treatment stops. Your radiation oncologist will discuss any possible long-term side effects with you.
