Partial Breast Irradiation Using Interstitial Permanent Palladium-103 Seed Implant

25 women with low stage (pT1pN0) breast cancer, grade 1 or 2, will be accrued for adjuvant partial breast radiotherapy using PBSI and prospectively followed for 5 years. The primary aims is to evaluate implant quality according to recognized dosimetric parameters. Secondary aims include elaboration of approaches to different technical scenarios imposed by variation in seroma size, shape and location within the breast (expanding the technical manual to include recommended approaches to implants in different sectors of the breast and in different size breasts), incorporation of the use of live 3D ultrasound in the procedure (as opposed to current use of 2D US), assessment of patient acceptance and quality of life, physician assessment of cosmesis, assessment of toxicity, and recording of cost to the patient and health care system compared to alternate forms of breast radiotherapy.