Dosimetry Instructions for Personal Radiation Dosimeters
What types of dosimeters are there?
Do I need a dosimeter if I am pregnant?
How do I wear my dosimeter?
When do I return my dosimeter?What do the results of the dosimeter mean?
Is there a special dose limit for pregnant workers?
How do I terminate a dosimeter?
What does the dosimeter do?
A radiation dosimeter does not provide protection but detects and measures radiation that you have been exposed to. A dosimeter will detect gamma radiation, x-radiation and and high-energy beta radiation. Dosimeters cannot detect low-energy beta radiation emitted by carbon-14, tritium or sulfur-35.
What types of dosimeters are there?
We use two types of dosimeters for radiation monitoring, aluminum oxide (trademark name Luxel) and TLDs (thermoluminescent dosimeter). The Luxel badge measures whole body dose from x-radiation, gamma radiation and beta radiation. The Luxel badge is a flat cartridge held in an hexagonal grey clip and is worn on the collar. The TLD measures extremity dose (finger, hands, etc.) from x-radiation, gamma radiation and high-energy beta radiation. The TLD chip is contained in a plastic ring which is worn on the dominant hand. For more details on the proper procedure for wearing dosimetry see the section labeled "How do I wear my dosimeter?"
Who needs a dosimeter?
Radiation workers who operate fluoroscopy units are required to wear one or more dosimeters. Other radiation workers who operate x-ray machines, administer radiation therapy, or are exposed to other sources of gamma or high energy beta radiation are generally required to wear one or more dosimeters.
The following table provides general badging guidelines for those who
handle radiation sources or dispersible isotopes. If you have not been
issued a dosimeter and feel that you should have a dosimeter please call
our office (581-6141).
| Isotope | Activity used per month |
|---|---|
| 3H | no badge issued |
| 14C | no badge issued |
| 32P | 5 mCi |
| 33P | 45 mCi |
| 35S | no badge issued |
| 86Rb | 5 mCi |
| 125I | 9 mCi |
How do I get a dosimeter?
New personnel who will use radiation sources must complete the "RADIATION USER PERSONAL DATA" form (RPR 1), if they have not done so already. When the Radiation Safety Office determines that a dosimeter is needed, it will be issued in approximately two weeks.
Do I need a dosimeter if I am pregnant?
Current occupational radiation control rules impose a special dose limit specifically for the unborn child (embryo/fetus) of any radiation worker who formally declares her pregnancy. This dose limit is 500 millirem during the entire pregnancy. It is also recommended, as a further precaution, that the dose to an embryo/fetus be further limited to no more than 50 millirem per month. Normally the dose limit for a non-pregnant radiation worker is 5000 mrem per year.
A pregnant radiation worker is not required to declare her pregnancy. However, for the RSO to apply a lower dose limit, implement any control measures or dosimetry the pregnancy must be declared in writing to the Radiation Safey Officer and the worker's supervisor.
Dosimetry is not always necessary for a pregnant radiation worker. If you would like to discuss this with a health physicist, please do not hesitate to contact our office at 581-6141.
Additional information on this website for Pregnant Workers
How do I wear my ring dosimeter?
The ring badge should be worn on a finger with the label facing the radiation source, i.e. toward the palm of the hand where the highest exposure occurs. Protect the ring badge from contamination by wearing it inside a glove. Check the badge as part of your routine survey for personal contamination. Ring badges are available in small, medium and large sizes; if a ring doesn't fit, please request a different size!
Persons issued radiation dosimeters are required
to wear them at all times when working with radiation sources. When
not being worn, they must be kept in a location protected from radiation
and heat.
How do I wear my whole body dosimeter?
Radiation users issued single whole body badges should wear them on their collar with the label facing out.
Users of fluoroscopy units should have two badges, a collar badge and a waist badge. The collar badge will have a black icon and must be worn on the collar outside of the lead apron. The waist badge will have a yellow icon and must be worn under the lead apron at waist level. The purpose of the two badges is to provide additional information for accurately determining the effective dose equivalent received by fluoroscopy users wearing protective lead aprons.
Persons issued radiation dosimeters are required
to wear them at all times when working with radiation sources. When
not being worn, they must be kept in a location protected from radiation
and heat.
When do I return my dosimeter?
Dosimeters are exchanged every month. If expected dosimeters are not received by the second working day of the month, please call Radiological Health at 581-6141.
Dosimeters must be exchanged promptly and returned to our department within 5 working days so we can mail them to the processor in a timely manner.
Dosimeters that arrive in our office after the 5th
working day of the month they are due are considered to be late and will
be assessed a $10 fee. Dosimeters returned more than 30 days late, or
damaged, or misused in any way that invalidates the reading, are considered
to be lost and will be assessed a $15 fee. The fees are billed to the
department, which is responsible for obtaining reimbursement from the
individual.
What do the results of the dosimeter mean?
The primary occupational whole body dose limit is 5,000 millirems per year, effective dose equivalent. The dose limit to the extremities (hands, fingers, etc.) is 50,000 millirems per year.
Is there a special dose limit for pregnant workers?
The embryo-fetus may be more susceptible to radiation effects than an adult and is, therefore, subject to a lower dose limit. The dose limit for the embryo-fetus is 500 millirems during the entire gestation period. As a further precaution, it is advisable to keep the monthly doses below 50 millirems. This degree of protection for the embryo-fetus can only be achieved with the cooperation of the employee, who should notify her supervisor as soon as the pregnancy is known. The limit is enforceable only if the pregnant employee gives written notice to the RSO and to her supervisor, who shall also notify the RSO. Please see our Pregnant Radiaiton Worker page
How do I terminate a dosimeter?
Responsible users should ensure that individuals leaving their group return their final dosimeters and notify Radiological Health of their termination (user termination checklist RPR 1C). Dosimeters provided beyond the month of termination due to lack of notice may be subject to an additional charge billed to the responsible user's account.
If you have any questions about dosimeter use or exchange, please contact our department at 581-6141.
If you are looking for information on Dosimetry services, look under the Product Resources tab in our Links section.
