Off-air monitoring for PET-centers. Practical aspects

During operation of a PET-Center, the air is contaminated by radioactivity. Apart from accidents, this contamination may be caused, for example, by neutron-induced air activity during operation of a cyclotron, leaks in the chemical process units and the use of radioactive gases on patients. Therefore, the room air as well as the waste air have to be monitored. Due to lack of experience, there is still uncertainty regarding the scope and the proper layout of such measuring systems. This paper will discuss the principle of a waste air monitoring system which features adequate sensitivity as well as the required retaining capability in case the activity is exceeded. (author)