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Q: Why do I need a control dosimeter?
Q: How does a radiation film badge work?
Q: How long can I wear my Film or TLD Dosimeter?
Q: How long can I keep my Film or TLD Dosimeter before I need to have it processed?
Q: What happens if I lose my dosimetry badge?
Q: How is the film analyzed to determine whether or not exposure was received
during an occupational exposure?
Q: What does an asterisk mean on my dose report?
Q: How are exposure levels classified so I know I am within safe limits?
Q: What does it mean if I receive a dose of 10 or 11 mrem?
Q: How do I get a copy of my dose report?
Q: What is my lifetime dose or my dose history?
Q: What is the difference between TLDs and Electronic Personal Dosimeters?
Q: What type of Dosimeter is best for Nuclear Medicine Departments?
Q: Why do I need a control dosimeter?
A control badge is used to subtract background radiation exposure during transit and while the badge is stored at the customer's facility.
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Q: How does a radiation film badge work?
Radiation exposes (darkens) a piece of monitoring film similar to the way ordinary light exposes a piece of photographic film. Images appear on either type of film. Embedded in a film holder are rectangular filters made up of different thicknesses of plastic, lead and copper in order to capture appropriate radiation levels.
A calibrated light source and sensitive detectors are used to measure the amount of light that can pass through the film in each of the filtered areas. That information determines the type and energy of radiation exposing the film, and how much radiation is present. Without the filter patterns, there is not enough information available to determine the radiation type or how much was there.
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Q: How long can I wear my Film or TLD Dosimeter?
While TLD dosimeters have a practical useful life of up to twelve months, the maximum wear period for the film dosimeter is typically four months. After that time, it will be necessary for you to have a replacement badge sent.
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Q: How long can I keep my Film or TLD Dosimeter before I need to have it processed?
All dosimeters should be sent back for processing immediately after the end of the wear period. Listed below are the guidelines for determining how long you may keep your dosimeter before you must return it for accurate processing.
FILM: Monthly -180 days from the end of the wear period. Quarterly -120 days from the end of the wear period.
TLD: Monthly - 335 days from the end of the wear period. Quarterly - 270 days from the end of the wear period. Annually - Fixed date which may be changed manually (generally processed for up to three months past the end of the wear period).
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Q: What happens if I lose my dosimetry badge?
If your dosimetry badge is lost, the supervisor or person who supplies you with the dosimetry badge should be notified. Another dosimetry badge may then be ordered and received in the next few days as a replacement. For large institutions, the Radiation Safety Officer (RSO) or Health Physicist may have spare badges and they can issue a new one immediately. The RSO or employer can estimate a dose for the lost badges and that amount can be added to your dose history so that your dose history is always current.
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Q: How is the film analyzed to determine whether or not exposure was received during an occupational exposure?
A film dosimeter is comprised of a film packet, filters and a holder.
Film dosimetry is unique, in that each processor can use a specific type of film with varying number of filters and thicknesses. GDS utilizes Kodak Type 2 film that contains five specific areas of filtration for accurate assessment of exposures captured during a wear period.
Dose from film is assessed in many ways. GDS's film algorithm is based on approximately 2,000 irradiations at Battelle Pacific Northwest Laboratories. This is a very sophisticated dose algorithm, and provides very accurate and precise dose determinations.
An unirradiated film packet is clear, similar to film used in an X-ray facility in a medical office. When film is irradiated, there is a darkening of the film, and based on each of the five filtered areas, exposure levels are assessed.
If a film is irradiated while not in the holder, there is a uniform darkening across the entire film packet. If a film is worn during times of radiation exposure, the filter image on the film will be distinct, but blurred. If the film is irradiated in a stationary position, when the person was not occupationally exposed, the filter patterns are very distinct, crisp and no blurring whatsoever.
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Q: What does an asterisk mean on my dose report?
Global Dosimetry places an asterisk when the calculated dose is less than the "minimum reported dose" which signifies that the calculated dose has no statistical relevance, for example:less than 10 mrem whole body film or TLD. Global Dosimetry reports the actual dose when the dose is greater than the minimum reportable dose.
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Q: How are exposure levels classified so I know I am within safe limits?
Radiation workers adhere to the concept of ALARA that means, "As Low As Reasonably Achievable". When you have a dose of 10 to 20 mrem or even 100 mrem you are significantly below the maximum amount of radiation you can receive by state and federal regulations in one year. The Deep Dose Equivalent (Whole Body) limit is 5,000 mrem/year. So receiving a dose over the year of 100 mrem is only 2% of the regulated dose limit you can receive. Practicing safe radiological procedures is the best practice you can do.
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Q: What does it mean if I receive a dose of 10 or 11 mrem?
A dose of 10 or 11 mrem is not that significant. However, if you have previously seen only asterisks, a dose of 10 or 11 mrem may be unsettling. One of the reasons you may have received a higher dose is that the control badge might not have been shipped back to GDS with your used personal badges.
A control badge measures any "background" exposure which is separate from the exposure a person receives from occupational work. The control badge is read like any other badge and that amount of radiation found on your control badge (includes natural background and any transit dose) is subtracted from your badge reading. So if your badge reads 19 mrem and the control badge is 10 mrem then your total dose is 9 mrem. If that is the case then an asterisk will show up in your dose column. If your control badge is not sent back then the full dose from your badge will report the total 19 mrem dose and not an asterisk. Therefore you should always send the control badge back so that we can report an accurate measurement.
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Q: How do I get a copy of my dose report?
Your radiation safety officer or in the case of small office practitioners, the dentist, the veterinarian or physician in charge can supply you with a copy of your dose report. Also the account owner should be able to explain the report to you and the amount of dose you have received. If the owner does not have a current copy, they may request a current copy from Global Dosimetry customer service.
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Q: What is my lifetime dose or my dose history?
The last four columns of the report deal with your lifetime to date deep dose equivalent. The lifetime column reports the amount of dose or exposure you have received over your lifetime as a radiation worker. A radiation worker is defined as any person who works in a radiation or radiation-producing environment. This definition includes people who take X-rays in dentist or veterinary office.
If you change employment from one office to another, you can have your previous records forwarded to your new employer, who can have their current dosimetry service updated your records on the dose report. Under federal regulation 10CFR20.2104 your previous employer may provide your current employer your lifetime dose. Keeping your records up to date protects you and your current employer.
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Q: What is the difference between TLDs and Electronic Personal Dosimeters?
The TLD accumulates dose from the time it is first used until the time it is processed. An ED only measures exposure while the unit is on and captures radiation exposure on a real time basis.
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Q: What type of Dosimeter is best for Nuclear Medicine Departments?
All of GDS’s whole body dosimeters, film and TLD, are fully accredited by NVLAP and meet all of the testing requirements per ANSI N13.11-2001. This includes all gamma, X-ray, beta and neutron energies, per the Standard. The GDS film badge is routinely worn in Nuclear Medicine facilities accurately assessing the dose received by Nuclear Medicine employees. As with all dosimeters, in certain radiation work environments, specific dosimeter types may be more advantageous than others. GDS recommends that in those radiation work environments where the film badge is not the most advantageous for the type of work performed, that the TLD be considered as an alternative whole body dosimeter. GDS health physicists will be happy to discuss the department’s monitoring requirements in order to wear the most appropriate dosimeter.
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