The Scientific Foundations of Dosimetry Systems: Ensuring Reliable Radiation Monitoring

In the world of radiation-related fields, dosimeters serve as critical safeguards against radiation overexposure. A sound understanding of how these devices function is essential for professionals working in these fields. Dosimeters work by undergoing measurable and reproducible changes in their physical properties upon exposure to ionizing radiation energy. This alteration enables them to provide a quantitative measurement of the absorbed dose¹.

The Science Behind: Diverse Dosimetry Systems

Film Badges: Film badges contain a radiation-sensitive film that darkens when exposed to radiation. The degree of darkening is proportional to the radiation dose received. After wearing the badge for a specified period, it's developed, and the darkened film is analyzed to quantify the amount of exposure.
Thermoluminescent Dosimeters (TLDs): TLDs contain crystals that store energy when exposed to radiation. When the crystals are later heated, they release this energy as light. The intensity of the emitted light is directly proportional to the amount of radiation exposure, which can then be measured to determine the dose.
Optically Stimulated Luminescence (OSL) Dosimeters: In OSL dosimeters, exposure to radiation causes electrons to get trapped in the energy bands of the dosimeter's material. These trapped electrons can be released by exposure to light, and the resulting luminescence is measured to determine the radiation dose.
Diode/Electronic Dosimeters: Known for their high sensitivity and instant read-outs, diode dosimeters provide real-time dose readouts on the dosimeter screen and are commonly used in high-radiation environments for immediate monitoring. However, they must be calibrated regularly for consistent accuracy.
Direct Ion Storage (DIS) Dosimeters: Incorporating this newest and most advanced dosimetry technology, Instadose^® wireless dosimeters combine DIS technology with SmartMonitoring™ technology that enables high sensitivity, precision and accuracy for on-demand dosimetry. This makes it uniquely possible to monitor exposure levels on-demand and automatically – without having to return dosimeters for offsite processing, providing an added layer of security.

Each type of dosimeter badge has its own unique way of functioning, but they all serve the same general purpose: to measure and record exposure to ionizing radiation, thereby helping to ensure workers stay within safe exposure limits.

The Crucial Role of Calibration in Traditional Dosimetry Systems

One often overlooked aspect of effective dosimetry systems is the need for regular calibration. The calibration typically involves measuring background radiation with a control badge, which is then subtracted from the total radiation detected on each individual's badge. This ensures the most accurate readings and helps maintain compliance with state regulations. However, it's worth noting that Instadose badges are an exception to this rule. These advanced dosimeters employ proprietary algorithms that automatically compensate for background radiation, eliminating the need for manual calibration.

Frequency of Calibration

The frequency of calibration can vary based on state regulations and the type of dosimeter in use. For example, while some dosimeters may require quarterly calibration, specialized badges like fetal badges may require monthly checks. To understand the requirements for your industry, consult your Radiation Safety Officer (RSO). Failing to properly calibrate dosimeters can have serious repercussions, including hefty fines, machine shutdowns, or in extreme cases, business closure.

Technological Advancements

The field is continually evolving to reduce the need for frequent calibrations. For instance, the Mirion Instadose wireless dosimeter badge does not require manual calibration; its algorithm automatically compensates for background radiation. This feature allows for on-demand report generation without the need for mailing badges back for processing.

For more information on our Instadose brand of dosimetry badges and other products, visit www.instadose.com or call us at 1-800-251-333.

References:

1. ScienceDirect, "Comprehensive Biomedical Physics, Chapter 7," https://www.sciencedirect.com/referencework/9780444536334/comprehensive-biomedical-physics

2. E. Tchistiakova, A. Kim, W. Y. Song, and G. Pang, "MR-safe personal radiation dosimeters," https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874943/

3. Wrya Parwaie, Soheila Refahi, Mahdieh Afkhami Ardekani, and Bagher Farhood, "Different Dosimeters/Detectors Used in Small-Field Dosimetry: Pros and Cons," https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116321/