<p> CHARACTERISTICS OF COMMONLY USED RADIONUCLIDES</p><p>Radionuclide Radiation(s) emitted and energy Radiological Biological Effective Critcal Maximum Shielding Special Half-Life Half-life Half-life Organ Permissible Required Considerations Body Burden H-3 Beta particle: Emax – 18.6 keV 12.3 years 12 days 12 days whole body 1 mCi whole body None None Emean – 5.7 keV C-14 Beta particle Emax – 156 keV 5730 years 10 days 10 days whole body .4 mCi whole body None Do not generate carbon Emean – 49 keV fat .3 mCi fat dioxide which can be inhaled. P-32 Beta particle: Emax – 1709 keV 14.3 days 1155 days 14.1 days bone .006 mCi bone 1 cm P-32 is highest energy Emean – 690 keV .030 mCi whole Plexiglass radionuclide used in body research labs. Avoid bremstrahlung x-ray production by shielding with plexiglass and not Lead. P-33 Beta particle: Emax – 246 keV 24.4 days 1155 days 23.9 days bone .032 mCi whole 1 cm None body Plexiglass S-35 Beta particle: Emax – 167 keV 87.4 days 623 days 76 days whole body .4 mCi whole body None Open vials in ventilated Emean – 49 keV testes .090 mCi testes enclosures to prevent inhalation Ca-45 Beta particle: Emax – 257 keV 165 days 49.3 days 162 days bone .030 mCi whole 1 cm None Emean – 86 keV body Plexiglass .01 inch Al foil Cr-51 Gamma photon: 320 keV 28 days 616 days 27 days lower large .800 mCi whole 3.2 mm Lead None X-ray: 5 keV intestines body Co-57 Gamma photons: 122 keV (85.5%) 270.9 days 276 days 9.2 days lower large .200mCi whole 3.2 mm Lead None 136 keV (10.8%) intestines body 14 keV (9.5%) 692 keV (.16%) I-125 Gamma photon: 35 keV (7%) 60 days 138 days 41.8 days thyroid .00115 mCi .25 mm Lead May be volatile when X-ray: 27-32 keV thyroid opening vial; therefore .006 mCi whole open vials in ventilated body enclosures such as certified hoods. Do not make I-125 solutions acidic or do not store frozen; both lead to formation of volatile elemental iodine I-131 Beta particle: Emax – 806 keV 8.04 days 138 days 7.6 days thyroid .00014 mCi 12.7 mm Same as 1-125. Additional Emean – 180 keV thyroid Lead requirements for gamma Gamma photons: 364 keV (81.8%) .050 mCi whole radiation shielding 637 keV (7.2%) body 284 keV (5.9%) 80 keV (2.4%) 723 keV (1.8%) http://ehs.unc.edu/radiation/characteristics.doc January 2003 </p>