The NCRP recommends an annual lens of eye EfD limit to the occupationally exposed of

The NCRP recommends an annual lens of eye EfD limit to the occupationally exposed of

• A. 0.5 mSv.
• B. 5.0 mSv.
• C. 50 mSv.
• D. 150 mSv.

Answer: (D)

The main idea is that the lens of the eye is especially radiosensitive, so there is a tissue-specific dose limit to protect against cataracts from occupational exposure. The limit is expressed as the lens-equivalent dose (EfD) and, for photons, equals the absorbed dose in the lens in millisieverts since the radiation weighting factor is essentially 1. The NCRP set an annual EfD limit of 150 mSv for the lens to keep the risk of radiation-induced cataracts at a very low level over a worker’s year, serving as a protective ceiling for eye exposure. The numbers 0.5 mSv, 5 mSv, and 50 mSv are not used because they would either be far too low to be practical for protecting the lens or earlier guidance that has since been superseded by the 150 mSv figure for occupational eye dose. In practice, eye-dose monitoring and protective measures (like leaded eyewear and shielding) help ensure the lens dose stays below this limit.

The main idea is that the lens of the eye is especially radiosensitive, so there is a tissue-specific dose limit to protect against cataracts from occupational exposure. The limit is expressed as the lens-equivalent dose (EfD) and, for photons, equals the absorbed dose in the lens in millisieverts since the radiation weighting factor is essentially 1. The NCRP set an annual EfD limit of 150 mSv for the lens to keep the risk of radiation-induced cataracts at a very low level over a worker’s year, serving as a protective ceiling for eye exposure.

The numbers 0.5 mSv, 5 mSv, and 50 mSv are not used because they would either be far too low to be practical for protecting the lens or earlier guidance that has since been superseded by the 150 mSv figure for occupational eye dose. In practice, eye-dose monitoring and protective measures (like leaded eyewear and shielding) help ensure the lens dose stays below this limit.