Comparison of Physical Data of Commonly Used Radioisotopes

Radionuclide H-3 C-14 S-35 P-33 P-32 I-125 I-131
Physical Half Life 12.3y 5730y 87.4d 25.4d 14.3d 60d 8.04d
Maximum Beta Energy 19keV 156keV 167keV 249keV 1710keV n/a 606keV
Range of Maximum Energy Beta Particle (in air) 4.7mm 22 cm 24 cm 46 cm 6m n/a
Dose Rate at 1 cm from a 1mCi BetaPoint 0 300rad/h 300rad/h 300rad/h 300rad/h n/a
Most Prominent Gamma Photons n/a n/a n/a n/a n/a 27keV
Gamma Ray Exposure Rate at 1 cm from a 1mCi PointSource n/a n/a n/a n/a n/a 1.4R/h 2.16R/h
Annual Limit on Intake - ALI (Oral)* 80mCi 2mCi 6mCi 3mCi 0.4mCi 0.02mCi 0.03mCi
Type and Thickness of Shielding Recommended for mCi Amounts None None None None Plexiglass
3/8 inch
1/8 inch
2 inch

*ALI-intake of a given radionuclide which would result in a committed effective dose equivalent of 5 rems or a committed dose equivalent of 50 rems to an organ or tissue.

For further information concerning Physical Data of Radioisotopes contact William Fendt or call 831-1434.