Dosimetry
Exposure Limits
State and Federal regulators set low-risk annual exposure limits. Additionally, the Radiation Safety Committee set lower exposure goals based on the principle of "As Low As Reasonably Achievable" (ALARA). The annual occupational exposure limits and goals are shown below:
Annual Occupational Exposure Limits
The occupational dose limits are set so that an exposed person will not exceed the safe industry risk while working with radiation (at the annual exposure limit for a 50-year period). Declared pregnant workers have lower limits that include additional considerations for the embryo/fetus.
Most users' radiation exposures are well below Harvard's exposure goals. In addition, the RSC has set Investigation Levels, which would initiate an investigation by the RPO. Based on a review of the exposure(s), the RPO will recommend appropriate safety measures to maintain exposures ALARA. These Investigation Levels (note these are per calendar quarter) are shown in the table below along with the annual exposure goals.
ALARA Goals and Investigation Levels
| Definition of Terms | |
| Extremities: | Are those parts of the body located from the elbows and knees down. |
| Investigation Level: | Are set dose values, which, if exceeded, would prompt investigation of the exposure and safety measures by the Radiation Protection Office. |
| mrem: | Is the unit of measure for the equivalent dose (measure of effect on human tissue). It is read as "millirem". |
| Trunk: | Is that part of the body from the knees and elbows up. This includes the internal organs within, as well as the reproductive organs. |
| Whole Body: | Refers to the trunk of the body and the head. |
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