抄録
We set up in our hospital a new type of teletherapy unit with pneumatic transference containing one hundred curies of cobalt-60 coin typed sources.
After a repetition of tests, a considerable amount of radioactive contamination was found on various parts of the unit and on the floor of the room in which the unit had been set up.
We surveyed the contamination of the unit and found that this had occured because of a leakage of cobalt-60 dust from the source capsule, namely by its incomplete encapsulation. We also made a survey on some telecobalt units of a conventional type, and got some positive findings.
In this report causes and countermeasures are discussed concerning the leakage of cobalt-60 which caused a considerable amount of contamination.
To prevent radiation hazards because of radioactive contamination, periodical wipe tests should be made on the cobalt-60 units.
