Thermoluminescent Dosimetry Service

What are Dosimeters?

Dosimeters are devices that store information about exposure to radiation. The crystals in Thermoluminescent dosimeters or TLD’s undergo a structural change that remains essentially stable until the crystal is heated.  When heated, the stored energy is released as light, which can be measured and related to the level of radiation exposure.

According to ANSI/HPS N13.11-2001 i.e. American National Standard Institute / Health Physics Society, it is mandatory to measure the radiation at 0 to 60 degrees angle. Panasonic TLDs are best suited for this application. The TLD captures exposure levels from various angles and does not run the risk of overestimation due to the wide range of radiation levels. The TLD badge provides a more accurate determination of exposure versus other monitoring devices.

TLD dosimeters are one of the most advanced applications of Thermoluminescent detectors. The reason for this is that, according to the new 10 CFR Part 20 Guidelines of the US NRC, modern TLD dosimeters measure the skin dose, eye dose and deep dose specified in this regulation, in addition to the dose due to other nuclear particles. Thus, modern TLD dosimeters consist of at least four separate TL detectors, which are shielded by materials of various compositions and thicknesses, to allow for discrimination of photon energies and the nature of the incident radiation.

Thermoluminescent Dosimeter badges should be worn by x-ray professionals whose work involves a direct or potential exposure to radiation.

We provide a monitoring service which processes exposed TLD Badges on a regularly scheduled basis using state-of-the-art technology and dose assessment algorithms.

The TLDs detect exposure with four independent detection elements and are capable of estimating doses at three tissue depths. The automated process for badge reading and report generation eliminates the chance of human error. All records are electronically stored for future reference.

The badges are small, lightweight and clip easily to clothing. Each badge is punch coded with an ID number for identification and tracking.

What is a Control Badge?

A control badge is provided free of charge for each cycle and plays a very important part in the monitoring system. It is used to determine background exposure readings during transit and while the badge is stored in the clinic. DO NOT WEAR THIS CONTROL DOSIMETER. This control dosimeter should be stored away from the radiation sources and/or outside of the x-ray rooms. It should be placed in an area free from radiation, high temperature and humidity. Do not keep it inside a drawer or any other container.

It is of utmost importance that the correct control be returned with the appropriate shipment.

How does the service work?

The clinic will receive new badges for every employee every three months along with a reply envelope for returning the badges for processing and reporting.

At the end of the wear period, all the old badges and the control badge MUST be returned together.

Do not allow any objects to cover the badge. Wear your badge throughout the work day. Do not take the TLDs home or expose them to high temperatures or high humidity. TLDs should be worn only by the individual whose name appears on the label. Do not share or make changes to the TLD.

Due care should be taken to avoid contamination of the dosimeters.

Our laboratory is accredited by the National Institute of Standards and Technology through the National Voluntary Laboratory Accreditation Program.

What is an Occupational Radiation Exposure Report (Dose Report)?

Once the TLDs have been returned to our laboratory, a Dose Report will be issued. A printed report will be sent to your clinic for your records. The Report shows the type and amount of exposure to each employee. The report includes the monitoring period, the dose equivalent for the current monitoring period, year-to-date and lifetime dose for each returned badge. It also mentions the annual exposure limits. If any reading should ever exceed the safety standards, the clinic will be contacted by phone by an authorized representative.  Any further copies of the dose record can be obtained by contacting the laboratory.

DOSE EQUIVALENT – product of the absorbed dose in tissue, quality factor, and all other necessary modifying factors at the location of interest.
DEEP DOSE EQUIVALENT (DDE) – incremental measurement in rem for dose equivalent at a tissue depth of 1 cm. Applies to whole body exposure.
SHALLOW DOSE EQUIVALENT (SDE) – incremental measurement in rem for dose equivalent at a tissue depth of 0.007 cm. Applies to external exposure of the skin or an extremity.
EYE DOSE EQUIVALENT (EDE) – incremental measurement in rem for dose equivalent at a tissue depth of 0.3 cm. Applies to external exposure of the lens of the eye.

Why should we use a TLD Program?

Your X-Ray staff knows that over exposure to ionized radiation can present potentially serious health problems. In addition, over exposure may impact an employee’s ability to continue working in the current environment. Without accurate monitoring, you and your employees will have no continuing way of managing their radiation exposure.

What if we are using another service?

Not a problem. After you receive our TLD badges, simply return the old ones to your provider. Then once they send you a final report, make a copy of that and send it to us so that we can include the data in our records of total lifetime exposure for each badge wearer.