The system and methods of the invention partially shields the radiation dose to the skin and/or other anatomical organs by using magnetically responsive material that blocks radiation, which may be fine grains of iron or other ferrous powder for example. The powder is typically injected into an IB applicator, along with inflating saline solution in case of MSB, when a skin spacing problem is encountered, or there is a risk of high doses being delivered to the critical organs surrounding a lumpectomy cavity, for example. A slight magnetic field of predetermined configuration will be applied externally to arrange the shielding material internally under the segment of surface of the IB applicator where the skin spacing is typically less then 7 mm, thereby protecting the skin from radiation damage. Monte Carlo studies to develop parameterizations for treatment planning with the IB applicator utilizing the suggested shielding material is also provided. In one aspect, the improvement to the IB system allows better cosmetic outcome in breast conserving therapy, and should allow more women to take advantage of BCT.
