Personnel Monitoring

Personnel Monitoring - Dose Detectives

• Objective: Quantify individual occupational radiation doses; ensure safety.
• Principle: ALARA (As Low As Reasonably Achievable) guides all practices.
• Monitored Individuals: Radiation workers potentially exceeding 10% of annual dose limits.
• Key Annual Dose Limits (ICRP/AERB):
  • Effective Dose (Occupational):

    ⭐ Annual effective dose limit for occupational radiation workers is 20 mSv/year, averaged over 5 years (not exceeding 50 mSv in any single year).

  • Equivalent Dose (Occupational):
    • Lens of Eye: 20 mSv.
    • Skin (localised): 500 mSv.
    • Hands & Feet: 500 mSv.
  • Effective Dose (Public): 1 mSv.
  • Pregnant Worker (to foetus, post-declaration): 1 mSv for remainder of pregnancy.

Personnel Monitoring - Dosimeter Zoo

⭐ The TLD badge using Lithium Fluoride ($LiF:Mg,Ti$) is widely used in India; its main advantage is tissue equivalence and sensitivity over a wide dose range.

Personnel Monitoring - Badge Business

• Purpose: Quantify occupational radiation exposure. Mandatory if dose likely > 1 mSv/year.
• Common Types:
  • TLD (ThermoLuminescent Dosimeter): LiF; heat readout. Most common.
  • OSLD (Optically Stimulated Luminescence): Al₂O₃; laser readout; higher sensitivity.
  • Film Badge: Older; heat/humidity sensitive.
• Wearing Protocol:
  • Primary: Chest/waist, under lead apron (for effective dose $E_{eff}$).
  • Secondary: Collar, outside lead apron (lens/thyroid). Optional.
  • Ring: Hands (e.g., interventional procedures).
• Frequency: Change 1-3 monthly (typical for TLD).
• Care: No tampering/sharing; store away from radiation when not in use.

⭐ For staff wearing lead aprons, the primary dosimeter should be worn under the apron at chest or waist level to monitor effective dose; a second dosimeter may be worn at collar level outside the apron for lens/thyroid monitoring if high exposure is anticipated to these areas.

Personnel Monitoring - Safety Scorecard

• Goal: Ensure occupational exposure is ALARA & below AERB dose limits.
• Devices: TLDs, OSLDs, DIS. Monitored by RSO.
• AERB Annual Dose Limits (Worker):
  • Effective Dose: 20 mSv/year (averaged over 5 yrs, max 30 mSv in 1 yr).
  • Lens: 20 mSv/year.
  • Skin/Extremities: 500 mSv/year.
• AERB Investigation Levels (ILs) for monitoring period:
  • IL I: 3/10th of annual limit.
  • IL II: 6/10th of annual limit.
  • IL III: 10/10th of annual limit.

⭐ Investigation Level I (3/10th of annual limit for monitoring period) as defined by AERB mandates an inquiry by the Radiological Safety Officer (RSO).

• Actions on Exceeding Limits:

High‑Yield Points - ⚡ Biggest Takeaways

• TLD (Thermoluminescent Dosimeter), typically CaSO₄:Dy, is the most common personnel monitoring device in India, measuring cumulative dose.
• Worn at chest level, it's read every 3 months.
• Film badges are older; pocket dosimeters (e.g., quartz fiber) offer immediate readings.
• OSL dosimeters (Al₂O₃:C) are read by laser, offering re-read capability.
• Monitoring is mandatory if annual dose likely exceeds 1 mSv.
• Occupational effective dose limit: 20 mSv/year (averaged), max 50 mSv in one year_