North American Scientific Inc. completed the previously announced sale of its Nomos Radiation Oncology business to privately-held Best Medical International Inc. The sale by the Chatsworth-based company allows it to better concentrate on breast cancer treatments and prostate brachytherapy products, said North American Scientific President and Chief Executive Officer John Rush. “We believe these products will allow us to address an $800 million market opportunity in the U.S. and we are excited to pursue this strategy,” Rush said.