Statement: There is no difference in results or cohort size between cohort 1 and 2 of the primary trial, the increase in Gy has no notable effect.
Primary_evidence: Outcome Measurement:    Feasibility of PBI Directed External Radiotherapy as Measured by Percentage of Participants Achieving a Dosimetrically Satisfactory Treatment Plan   -The study will be deemed infeasible if more than 4 patients cannot be given treatment because her tumor is such that a dosimetrically satisfactory treatment plan cannot be devised for her.   Time frame: Within 1 year of protocol registration Results 1:    Arm/Group Title: Cohort 1 (36 Gy)   Arm/Group Description: 36 Gy in 9 fractions BID x 4 1/2 treatment days   Partial Breast Irradiation (PBI)   Overall Number of Participants Analyzed: 50   Measure Type: Number   Unit of Measure: percentage of participants  100 Results 2:    Arm/Group Title: Cohort 2 (40 Gy)   Arm/Group Description: 40 Gy in 10 fractions BID over 5 treatment days   Partial Breast Irradiation (PBI)   Overall Number of Participants Analyzed: 50   Measure Type: Number   Unit of Measure: percentage of participants  100