Ionizing radiation is a form of electromagnetic radiation that can produce ions or charged particles. Types of ionizing radiation include α-, β-, γ-, and x-rays. The metric unit of measure for radioactive decay is Becquerel (Bq), which is equal to one disintegration per second. One Curie (Ci), an older, nonmetric unit of measure, is equal to 3.7 × 1010 Bq.