Health Dictionary
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Iodine-125
Introduction
Iodine-125 is a radioisotope of iodine which has uses in biological assays and in radiation therapy to treat prostate cancer and brain tumors. Its half-life is around 60 days and it emits gamma-rays with maximum energies of 35 keV, some of which are internally converted to x-rays. Iodine-125 is created by the electron capture decay of Xenon-125, which is a synthetic isotope of Xenon, itself created by neutron capture of the slightly radioactive Xenon-124, which occurs naturally with an abundance of around 0.1%. Because of the synthetic production route of Iodine-125 and its short half-life, the natural abundance is effectively 0%.
Physical Data
Physical Data
- Element: Iodine
- Z: 54
- A: 125
- Atomic Mass:
- Density:
- Physical state: Solid at room temperature
- Isotopic abundance: 0%
- Radioactive: Yes
- T(1/2): 59.4 days
- Decay: Electron capture to Tellurium-125
- Emissions: Gamma-rays at 35.5 keV. 7% emitted, 93% internally converted to:
- 27.0 keV (113% abundance relative to 7% gamm emission)
- 31.0 keV (26%)
- 27-32 keV (14%)
- Half-value layer: 0.025 mm Pb
References
References
- Harper, P.V. ; Siemens, W.D. ; Lathrop, K.A. ; Brizel, H.E. ; Harrison, R.W. Iodine-125. Proc. Japan Conf. Radioisotopes; Vol: 4th Jan 01, 1961
- ORCBS