Physical Data:

Radiological Data:

• Critical organ:  thyroid
• Internal exposure through inhalation, ingestion, or absorption are primary concerns

Shielding:

• Lead 1/32 in for >1 mCi

Dose Information (assume point source):

• 100 cm from 1mCi - 0275 mr/hr
• 10 cm from 1mCi - 27.5 mr/hr
• 1 cm from 1mCi - 2750 mr/hr

Survey Instrumentation:

• NaI scintillation probe
• Liquid scintillation counter (LSC)
  • Ls window:  0 to 850
  • LS efficiency:  78%

Regulatory Compliance:

Special Considerations:
Volatilization of iodine is the most significant problem with this isotope.  Simply opening a vial of sodium [I-125] iodide at high radioactive concentration can cause minute droplets of up to 100Bq to become airborne.  Solutions containing iodide ions should not be made acidic nor stored frozen: both lead to formation of volatile elemental iodine.  As some iodocompounds can penetrate surgical rubber gloves it is advisable to wear two pairs, or polyethylene gloves over rubber.  In the event of suspected or actual significant contamination of personnel the thyroid should be blocked by administration of stable iodine as, for example, tablets of potassium iodate (170mg) or potassium iodide (130mg).  To render any spilled iodine-125 chemically stable the area of the spill should be trated with alkaline sodium thiosulfate solution prior to commencing decontamination.