Common Dosimetry Terminology

Fetal Badge

Badge supplied to a declared pregnant radiation worker to monitor radiation dose to the fetus for the term of the pregnancy.

Dose History

Lifetime history of occupational exposure to ionizing radiation. NRC Form-4.

Spare Badge

Extra badge sent at customer request for assignment to:

  • Visitors
  • New employees
  • Employees who have lost their normal dosimeter
  • Spiking - A customer practice of playing a little joke on dosimetry service companies by intentionally exposing a spare dosimeter to radiation to test the processor's ability to evaluate exposed dosimeters.

Area Monitor

Dosimeter used to monitor an area. Dose not assigned to a person.


Those portions of the body from the elbows to the knees, including the head.

Extremity Dosimeter

Dosimeter used to monitor dose to wrist, finger or ankle.

Millirem (mrem)

A unit of radiation dose that equates radiation exposure to biological damage. The yearly limit for occupational exposure to ionizing radiation is 5000 mrem.

Webster Calculation

When a Health Care Professional wears a protective (lead) apron to minimize radiation exposure while working in proximity to a radiation source, a badge is worn on the chest, beneath the apron, and at the collar. A Webster Calculation is then performed to determine the worker's true dose.

Minimum reportable dose

The minimum dose that can be reliably detected.