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Overview of the Module
This module provides information about the following topics:
At the University of Utah, radiation dosimetry is provided to monitor occupational radiation exposure for those workers who use radiation sources under certain conditions. University of Utah dosimeters should not be used to measure occupational doses received at any other institution or to measure doses from non-occupational sources such as medical X-rays.
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Your radiation dose is tracked using two methods, internal and external exposure. Internal dose is calculated based on bioassays. If an uptake occurs it can be detected in your thyroid (for Iodine users) or in your urine. Of course the potential for exposure has to exist first for there to be concern for actual internal exposure. Potential exposure situations occur when significant personal contamination, injury caused by a contaminated object or airborne radioactivity may have been inhaled. These all require a bioassay to be submitted to the Radiological Health office. These bioassays are not optional. A potential exposure can also occur when an individual handles a cummulative quantity of radioactive material, in dispersable form, exceeding 1 ALI per month. A routine bioassay must be submitted to the Radiological Health dept. This bioassay may be optional if and only if records of area and personnel contamination surveys of both the user and your analyst indicate no exposure to unconfined radioactive material. For directions on completing a screening urinanalysis click here.
Routine thyroid bioassays are provided by the RSO or can be requested at any time by contacting the Radiological Health Department
External exposure is measured using a dosimeter.
State and federal regulations require that those persons who are likely to receive 10% or more of the annual radiation dose limits must be provided with radiation dosimetry. This means that federal regulations require monitoring for any person likely to receive a whole body dose of 500 millrem or more or a skin or hand dose of 5000 millirem or more.
Under University of Utah requirements, you must wear dosimetry if:
- You operate x-ray machines (including X-ray diffraction equipment)
- You are a Declared Pregnant Worker working in a lab where x-ray and gamma emitters are used
- If you use radioactive materials under the following conditions:
| P-32 (and other beta emitters with energies > 250 keV) |
Used in amounts of 5 mCi or more /month. Not required for simple aliquoting from a stock vial |
| I-125 (and other x-ray or gamma emitters with energies < 100 keV) |
Used in amounts of 10 mCi or more /month. Not required for simple aliquoting from a stock vial |
| Fe-59 and Zn-65 (and other x-ray or gamma emitters with energies > 100 keV) |
Used in amounts of 0.5 mCi or more /month Not required for simple aliquoting from a stock vial |
| We do not badge H-3, S-35 and C-14 users (low beta emitters) |
These isotopes are not energetic enough to penetrate the layers of skin |
Examples of how the dosimetry criteria are applied
- If your lab receives a 5 mCi vial of P-32 and you briefly handle the 5 mCi vial to withdraw an aliquot of 100 uCi, you are not required to wear dosimetry.
- If you order 5 mCi of P-32 and you perform a synthesis using the entire 5 mCi, you are required to wear dosimetry.
More Information about Dosimeters
Additional information about dosimeters and about using and wearing dosimeters is available here.
Dosimetry is not routinely provided to workers who do not meet the criteria described in the Required Dosimetry section. For example, you will not be routinely provided with dosimetry if:
- You only use H-3, C-14, P-33 or S-35
- You use P-32 in amounts less than 5 mCi
- You use I-125 in amounts less than 10 mCi
Temporary Dosimetry
Temporary dosimeters are available for workers whose high-level radioisotope use is sporadic. Radiological Health maintains a supply of temporary dosimeters and can supply you with a temporary badge upon verification of need. Temp badges can also be issued to users while they are waiting for their permanent badge to arrive.
If you have concerns about your radiation exposure and would like to be monitored even though you do not meet the Required Dosimetry criteria, you may contact the Radiological Health Department directly. If you request dosimetry even though you do not meet the Required Dosimetry criteria, dosimetry will be provided for you for a year. After the first year of monitoring, Radiological Health will meet with you to review your dose history and to discuss whether dosimetry should be continued.
You've completed the last of the six Radiation Basics modules. You may now go to the test or you may go to any of the previous modules:
Go to the Radiation Basics Test Registration and Test
Go to the Radiation Safety Training Introduction
Go to the Radiation Properties Module (Module #1)
Go to the Background Radiation Module (Module #2)
Go to the Biological Effects Module (Module #3)
Go to the Government Regulations Module (Module #4)
Go to the Dose Limits Module (Module #5)
Go to the Dosimetry Module (Module #6)