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University of Pittsburgh

Dosimetry

Any individual who is occupationally exposed to ionizing radiation and is likely to receive a dose in excess of 10 percent of the applicable annual allowable limit will be issued a radiation monitoring device (radiation dosimeter). The radiation dosimeter is worn by the individual to monitor and track external radiation exposures. Individuals working with volatile or large quantities of unsealed radioactive material are required to undergo in vivo or in vitro bioassay measurements to assess the intake of radioactive material and determine the corresponding radiation dose. Thyroid probes are performed on workers handling I-131 and I-125 as sodium iodide, and urine bioassays are performed on workers handling high activities of beta emitters. In addition, bioassays are performed as part of the response to spills or accidental releases.

Reports of the personnel exposures and bioassay measurements are reviewed monthly by the Radiation Safety Office (RSO) to look for unusual or unexpected levels. In accordance with the as low as reasonably achievable (ALARA) philosophy, any exposures greater than 10 percent of the maximum permissible dose are investigated and reported to the University Radiation Safety Committee.

Guidelines for the Wearing of Personal Dosimetry

Purpose:  Dosimeters are issued to measure and record the amount of occupational radiation dose an individual receives as required by state and federal regulations.  Dosimeters are required to be issued if an individual is likely to receive greater than 10 percent of maximum permissible dose.

Types of dosimeters:  Whole body dosimeters are issued to monitor radiation exposure to the head and torso.  Ring dosimeters are issued to monitor radiation exposure to the hands.  The sensitivity is 1 mrem for the whole body dosimeter and 40 mrem for the ring dosimeter.

How to apply for radiation dosimetry: An application for personal dosimetry is required to be submitted to the Radiation Safety Office before dosimetry will be issued. The dosimeter form is below:

New Dosimeter Application

Frequency and process for exchange: Dosimeters are issued for either a one month or three month wear period. At the end of the wear period, replacement dosimeters will be distributed to you through the designated badge coordinator. Dosimeter holders are reused and are not to be returned with the used dosimeter.

Radiation exposure reports: A written report is issued by the dosimeter vendor, listing each individual and the exposure recorded. The reports are kept by the Radiation Safety Office for review and inspection by regulatory agencies.  You have the right to know what your measured radiation exposure is at any time.  Copies of the reports may be issued to the badge coordinators so that individuals may see their exposure.  Each individual is issued an annual report.

Lost or damaged dosimeter: If your dosimeter is damaged or lost, promptly contact the badge coordinator or the Radiation Safety Office so that a replacement dosimeter can be issued.

Pregnancy and fetal dosimeters: Declared pregnant workers may be issued a designated fetal dosimeter. Declaration of pregnancy involves the completion of a Pregnancy Declaration form and an interview with a health physicist from the Radiation Safety Office. Fetal dosimeters have a monthly frequency, and should be worn at the waist level underneath any lead garments.  Care should be taken to not switch the location of the fetal and collar dosimeters.

Where to wear your dosimeter:  Whole body dosimeters should be worn on the front of the body, in the area of the main torso, anywhere from waist to neck.  Individuals who wear lead garments should position the whole body dosimeter at the collar level, outside of any lead protection. Ring dosimeters should be worn on the hand most likely to be exposed, that is, the hand the closest to the sources of radiation.

General information:

Dosimeters do not protect you.

When not wearing the dosimeter, it should be stored in an area away from any radiation sources.

Dosimeters are issued to an individual.  Do not lend your dosimeter to another person, and do not wear another person’s dosimeter.

Do not wear your dosimeter for any personal medical procedures involving diagnostic

x-rays or nuclear medicine isotopes.