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In general, the larger the area of the body that is exposed, the greater the biological effects for a given dose. Extremities are less sensitive than internal organs because they do not contain critical organs. That is why the annual dose limit for extremities is higher than for a whole body exposure that irradiates the internal organs. Table 3 lists the exposure limits for different regions of the body.
Type of Body Area | Description | Allowable Limit (rem/year) |
Whole Body | The whole body is measured from the top of the head to just below the elbow and just below the knee. The limit is the sum of both internal and external exposure | 5 |
Extremities | The hands, arms below the elbows, the feet, and legs below the knees | 50 |
Skin | The entirety of the skin | 50 |
Organs or Tissues | All organs and tissues, including the brain | 50 |
Lens of the Eye | The cornea (the internal eye and retina are included in organs or tissues) | 15 |
Declared Pregnant Worker | If a worker declares their pregnancy (formally and in writing), their radiation exposure limits are reduced by a factor of 100; the exposure limit for the embryo/fetus is as shown | 0.5 |
Table 3: Dose Limits by Body Area
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This document originated from Word document XRF_Safety_374.doc (see Archived Versions below for a pdf copy) that was written by N. Lawler and A.Armstrong. Credits for subsequent changes to this document are given in the page history.
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