Dosimetry
Radiation dosimeter is an essential component of Texas Christian University (TCU)'s program, used to monitor the occupational exposure to ionizing radiation for personnel working with radioactive materials or radio-producing devices.
TCU's dosimeter monitoring program maintains a detailed dose history for each participant and insurance compliance with the ALARA principle (As low as Reasonable Achievable), helping to minimize radiation exposure while supporting a safe research and work environment.
Questions or concerns should be directed to the EHS office at safety@tcu.edu or 817-257-5395.
What you need to know
Dosimeters measure how much radiation you are exposed to from outside sources. After they are checked, they keep a permanent record of your total radiation dose at work.
By law, the University must provide dosimeters to anyone who might receive 10% or more of the allowed yearly radiation dose. To register, please complete and submit the Request for Dosimeter Service.
Dose Limits
The University implements the following occupational radiation dose limits, as outlined in the State of Texas regulations - 25 Texas Administrative Code 289:
| Dose Definition | Dose Limit |
| Total Effective Dose Equivalent (TEDE) (Whole body dose from external and internal sources) |
5,000 mrem/yr |
| Lens Dose Equivalent (LDE) (Dose to the lens of the eye) |
15,000 mrem/yr |
| Shallow Dose Equivalent (SDE) (Skin and Extremity Dose) |
15,000 mrem/yr |
| Declared Pregnant Woman | 500 mrem/yr |
Dosimeter Available
Two main types of dosimeter are available: (1) Whole body dosimeter and (2) Extremity dosimeter
Whole body dosimeter
- Worn in the front portion of the tuck of the body between the waist and shoulder and in approximately the same location each wear period.
- If you regularly wear a lead apron, you may be assigned two whole body dosimeters. One should be worn at your waist, under the lead. The other is worn at your collar, over the lead. Be sure to check the dosimeter so that you wear the appropriate dosimeter at the correct location.
Extremity Dosimeter
A ring that should be worn on your dominant hand.
- If you are assigned two rings, they are marked and should be worn on the correct hand for accurate exposure readings.
- The ring should be worn under your gloves. Care should be taken to ensure the ring is not removed with the gloves and disposed.
Storage
When not in use, dosimeters should be kept in an area with low background radiation, such as a badge board (designated area for storage), desk drawer, or a locker.
Dosimetry Series
Personnel are assigned to a dosimetry group, called a "series", based on the lab, clinic, or group they belong to. Each series is assigned an Area Dosimetry Coordinator, who is responsible for issuing, collecting, and returning dosimetry the EHS at the end of a wear period. The coordinator must also keep Radiation Safety informed of changes to personnel assigned to the series.
Returning Dosimeters for Processing
To ensure timely notification of high exposures and compliance with regulations, please return your dosimeters to your area dosimetry coordinator before the 15th day of the month following each wear period.
Unused Dosimeters
Dosimeters that are returned without the plastic tab broken are considered unused, and the dose measured on the dosimeter will not be assigned to the individual. Therefore, please break the plastic tab on the top of the dosimeter and place it in a dosimeter holder.
Dose History Records
Participants can check their personal dose history using the TCU Individual Dose Report Instructions. Other dosimetry records can be requested from the Radiation Safety Officer (RSO) as needed.
EHS utilizes Landauer for the University's dosimeter monitoring program. Access to dose history can be viewed through myLDR.
Pregnant Worker Declaration and Undeclaration
Pregnant radiation workers have the option to declare their pregnancy in writing or initiate the more restrictive fetal does limits noted in the chart listed above. This declaration can be revoked at any time for any reason. To declare or revoke a declaration, please complete and submit the applicable form to safety@tcu.edu.
Resources & Forms
Request for Dosimeter Service
TCU Individual Dose Report Instructions (work in progress)
Declaration of Pregnancy Form (work in progress)
Undeclaration of Pregnancy Form (work in progress)
Dose Report Explanation Guide (work in progress)
Training
Assignment of online safety courses is overseen by EHS and accessible through the
online HSI/SafetySkills Learning Management System. A TCU email address and ID is
required for access. For information regarding online training, or to request in-person
training, please contact EHS at safety@tcu.edu or at 817-257-5395.
Radioactive Material Training (RAM): In-person, submit a request
4-hour Radiation Safety and Protection for Bone Density Operators: In-person, submit a request
Radiation Safety Awareness - RAD-1.2
This online course addresses the types and effects of radiation, radiation exposure
hazards, workplace controls, and controls designed to prevent radiation exposure.