1. Tri-State Regional Cancer Center; Ashland Kentucky 41101 USA
2. McGill University; Montreal General Hospital; Medical Physics Unit; Montreal QC H3G 1A4 Canada
3. Maisonneuve-Rosemont Hospital; Radiation Oncology Department; Montreal QC H1T 2M4 Canada
4. Bard Access Systems, Inc.; Salt Lake City Utah 84116 USA