Calcium Cation Ca-47 is a rare calcium radioactive isotope which used in orthopaedics for bone formation evaluation. Calcium-47 has a half-life of about five days, which is long enough for numerous biological investigations and short enough to ensure that the person subjected to the investigation is not under prolonged irradiation. It emits gamma rays in addition to beta rays, and since the gamma rays are capable of penetrating many centimeters of tissue, determination of calcium-47 in the body is possible by external measurements. Unfortunately, calcium-47 is difficult to produce and did not use in routine medical practice