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Partial breast external beam radiation therapy
Source: Radiation for Breast Cancer, National Cancer Institute.
Source updated: Not stated in this source · Captured 2026-09-09.
Selected source text with whitespace normalised. This Triangle page is not an NCI PDQ summary. Independent clinical review is pending.
NCI patient treatment article for this disease Exact source article; not a clinically reviewed indication or current-standard recommendation.
Two techniques are commonly used to give external beam radiation treatment to the area where the cancer is or where it was located before it was removed by surgery:
Three-dimensional conformal external beam radiation (3DCRT) shapes the radiation beams to match the tumor’s shape, delivering a fixed dose of radiation from many directions.
Intensity-modulated radiation therapy (IMRT) also aims the radiation beams at the tumor from many directions. But IMRT also varies the intensity of radiation across the treatment area to allow higher doses of radiation to be given in areas needing more treatment and lower doses to be given in areas near sensitive organs or tissues.
Most people have treatment once a day, Monday through Friday, for 2 to 4 weeks.
Researchers are looking at other ways to adjust the radiation dose or schedule to reach the total dose of radiation more quickly or to limit damage to healthy cells.
Accelerated fractionation is treatment given in larger daily or weekly doses to reduce the number of weeks of treatment.
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Hyperfractionation is a smaller dose than the usual daily dose of radiation given more than once a day.
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Hypofractionation is larger doses given once a day or less often to reduce the number of treatments.
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Preserved source evidence · Independent clinical review pending · Not medical advice