Optimal implementation of individual therapy: It is important to individualize the planning and implementation of radiotherapy. CT-based treatment planning is encouraged to outline the target area and the volume of organs at risk. Uniformity of dose to large target areas and protection of normal tissue can be achieved using compensators such as wedges, the use of segmented forward planning, and intensity-modulated radiation therapy (IMRT). Breathing control techniques, including deep inspiratory breath-hold and prone position, may be attempted to further reduce the dose to adjacent normal tissues, particularly the heart and lungs. Pusher irradiation in breast-conserving treatment situations can be achieved using superficial electron, photon or brachytherapy. When chest wall scarring is indicated for push volume irradiation, electron or photon therapy is usually used. One image per week verifies the consistency of the daily settings. In some cases, more frequent imaging may be justified. Routinely 1 time per week. 1 imaging per day is not recommended. Whole breast irradiation: The target area is defined as the entire breast tissue. The whole breast should receive 46C50Gy/23C25fr or 40C42.5Gy/15C16fr (low split preferred). All dosing schedules are given 5 days per week. Push dose irradiation to the tumor bed is recommended in patients with a higher risk of recurrence. Typical additional doses are 10-16Gy/4-8fr. Chest wall radiotherapy (including breast reconstruction): Target areas include the ipsilateral chest wall, post-mastectomy scar, and drainage sites when indicated. Depending on whether this patient has had breast reconstruction, some techniques utilizing photons and/or electrons are reasonable. CT-based treatment planning is encouraged to determine lung and heart volumes and to minimize exposure of these organs. The dose is 46-50 Gy/23-25 fr of chest wall ± 2 Gy/fr of scar push to a total dose of approximately 60 Gy. All dose schedules are given 5 days per week. Special consideration should be given to the use of padding materials to ensure that the skin dose is appropriate. Regional lymph node irradiation: Target area outlining is best accomplished by utilizing a CT-based treatment plan. For paraclinoid and axillary lymph nodes, the depth of prescription varies depending on the patient’s anatomy. For identification of the internal breast lymph nodes, the internal mammary artery and vein can be used in lieu of this lymph node location (as these lymph nodes themselves are usually not visible on the planned images). Based on randomized studies and recent trials of post-mastectomy radiotherapy, radiation treatment of the internal breast lymph nodes should be carefully considered when regional lymph node irradiation is given. When dealing with internal breast lymph node volumes, CT treatment planning should be used to assess the dose to normal tissues, especially the heart and lungs, and to give importance to dose limitations. The dose for regional lymph nodes is 46-50 Gy/23-25 fr. All dose plans are given for 5 days. Accelerated partial breast irradiation (APBI): Preliminary studies of accelerated partial breast irradiation suggest that local control rates in patients with selective early-stage breast cancer are comparable to those treated with standard whole-breast radiotherapy. However, some recent studies have demonstrated poorer cosmetic outcomes with accelerated partial breast irradiation compared to standard whole breast irradiation. Follow-up is limited and studies are ongoing. Patients are encouraged to participate in clinical trials. If not eligible for trials, patients who may be suitable for accelerated partial breast irradiation are women ≥60 years of age, non-carriers of BRCA1/2 mutations, and women with single lesion T1N0ER positive tumors treated with initial surgery according to the American Society for Radiation Oncology (ASTRO) consensus statement. The histology should be invasive ductal or a well-defined ductal subtype and without an extensive intraductal component or lobular carcinoma in situ and the margins should be negative.