As ionizing radiation passes through matter, the intensity of the radiation is diminished.  Shielding is the placement of an “absorber” between you and the radiation source. An absorber is a material that reduces radiation from the radiation source to you. Alpha, beta, or gamma, x-ray radiation can all be stopped by different thicknesses of absorbers. Know the best source of shield for the radiation to which you are exposed. Radiation safety training, your supervisor, or a health physicist are all good resources to determine the proper shielding for the type of radiation you are exposed to. Shielding examples are shown in the below table:

Type of Radiation Permanent Temporary
beta radiation (e.g., Y90, Sm153) Aluminum, plastics Aluminum, plastics, wood, rubber, plastic, cloth
Gamma, x-rays, positrons (e.g., I131, F18) Lead, iron, lead glass, heavy aggregate concrete, ordinary concrete, water Lead, iron, lead glass, concrete blocks, water, lead equivalent fabrics such as gloves (for diagnostic x-ray machines only)