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IMPACT ON PEOPLE AND THE ENVIRONMENT
Dose

WORKED EXAMPLE: RADIOGRAPHY SOURCE NOT IN FULLY SHIELDED POSITION

 
  • One person, a radiation worker
  • Dose reconstruction: extremity dose in the range of 3.3–3.6 Gy
  • No deterministic effects

Scenario

A radiographer was disconnecting the source guide tube from the radiographic device and noticed that the source was not in the fully shielded position. The radiographer noticed that his pocket ion chamber was off-scale and notified the radiation safety officer (RSO). A dose reconstruction was done. The exposure device contained a 807 GBq Ir-192 sealed source. The radiographer was admitted to the hospital for observation and has been released. No deterministic effects were observed. The dose reconstruction estimated an extremity dose in the range of 3.3–3.6 Gy. Whole body dosimeter results revealed that the radiographer received a whole body dose of approximately 2 mSv.

What are the statutory annual dose limits for occupational exposure?

Whole Body 50 mSv (5 year average: 20 mSv)
Hand Dose (extremity) 500 mSv
Skin Dose (SDE) 500 mSv
Eye Dose (LDE) 150 mSv

 

INES procedure (click the highlighted flowchart items to follow the procedure)

Figure 4, page 145 of the Manual

Figure 5, page 146 of the Manual

Determine rating based on doses to individuals

Check the answer

Answer

The radiographer received an extremity dose in the range of 3.3–3.6 Gy (higher than the statutory limit for extremities)

Level 2 defines that there should be:
"Exposure of a worker in excess of statutory annual dose limits"

Level 3 defines that there should be:
"The occurrence or likely occurrence of a non-lethal deterministic effect"

Level 3 is not justified, therefore the radiography source not in fully shielded position would be rated at Level 2.