TY - JOUR T1 - Unnecessary exposure? JF - Canadian Medical Association Journal JO - CMAJ SP - 500 LP - 500 DO - 10.1503/cmaj.1050211 VL - 174 IS - 4 AU - Mithu Sen AU - Daniel Gregson AU - James Lewis Y1 - 2006/02/14 UR - http://www.cmaj.ca/content/174/4/500.1.abstract ER -