| 摘要 |
PROBLEM TO BE SOLVED: To shield radiation leaked from a ring part and to improve the weight balance of a plunger, by forming at least two spots of the tip end part and the rear end part of the plunger out of a composite material prepared by mixing tungsten powder into plastic resin. SOLUTION: At least two spots of this plunger, which are the tip end part 3 connected to a screw part 2 and the rear end part 4 to be in contact with fingers, are constituted of a radiation shield material formed of a composite material prepared by mixing tungsten powder into plastic resin. The shape of the radiation shield material constituting the rear end part is preferably a disk with a diameter larger than the inner diameter of a radiation shield container to be mounted when radioactive drug solution is administered from a pre-filled syringe. Parts of the plunger other than the radiation shield material are constituted of plastic resin and the border part with a different material is joined together by fusing plastic resin stronger than that in a case by only mechanical joining in combined forming of the plunger. |
