Staff dose calculation during a Cobalt-60 source stuck

One of the most postulated accidents in 60Co radiotherapy units is the source getting stuck, where one or more of the staff should enter the treatment room to deal with the problem. For such an accident, an emergency plan is important. A three-dimensional model of a 60Co therapy room has been done using the Monte Carlo code MCNP4B. The radiation safety measures taken and the drawings of the device are given together with suggestions for future use of the source for irradiation purposes. Moreover, the calculated results were compared with those of an experimental study dealing with this problem and were found to be in very good agreement. (author)