抄録
Leakage neutrons were measured around the labyrinth and the entrance of the treatment room for the 10 MV X-ray linear accelerator facility of Chiba University Hospital. A neutron rem counter and a BF3-counter surrounded by paraffin moderators were used for neutron measurements. An ionization chamber was used for scattered X-ray measurements.
Relative counting rate of leakage neutrons showed an exponential attenuation with the distance in the labyrinth and passage. Furthermore, it was found that the leakage neutrons decrease at the entrance door for shielding by about 20Dose equivalent rates for leakage radiations were 0.8 mrem/hr for neutrons and 0.5mrem/hr for scattered X-ray at the outside of the door.
These results indicate that the controlled area of our facility is satisfied the regulated value of the rule without any additional shielding for leakage neutrons.
