Abstract
Abstract The radiopharmaceuticals used in positron emission tomography(PET) are very short lived and generally must be produced in the hospital using a medical cyclotron. An essential byproduct during the cyclotron operation, from the point of health concern on medical personnel, is neutron emitted from (x,yn) reactions. So neutron for medical personnel health reasons cannot be ignored. The neutron dose rate in maze pathway of the Tzu Chi Medical Cyclotron was measured using bubble neutron dosemeters with various sensitivity during cyclotron operation, resulting a various intensity up to 3650μSv/h. Spatial distribution of neutron dose rate in the maze pathway is visualized by use of MATLAB graphical representation, reflecting the weakness of neutron shield on the slide door at the far end of the cyclotron maze pathway. The BF3 proportional neutron counter was also utilized for measure the neutron doses in the adjacent pharmacy room, maze pathway, utility room and Director's office. We discovered neutron dose rate is surging up during cyclotron operation. In Hualien from July of 2005 to October, five typhoons passed, we also used BF3 proportional counter to measure cosmic neutron in typhoon in order to find the relation to atmospheric pressure and rainfull.