Question

Briefly discuss some of the practical handling problems with TLD dosimeters in the extruded chip form. How are these problems solved by a TLD processor?

Answer 1

TLD (thermoluminescent dosimeter) dosimeters measures ionizing radiation exposure by measuring the intensity of visible light emitted from a crystal in the detector when the crystal is heated. It has following handling problems-

1. The signal is read only once- The signal is erased during the read-out cycle. It is easy to lose the reading.

2. TLDs are sensitive to light.

3. The storage in a TLD is not stable – Annealing heating cycle is needed.

4. Spurious TL signals are produced due to scraping of a TLD or its contamination by dirt or humidity.

5. The sensitivity is decreased or increased after a large dose received by a TLD- an additional anneal procedure is then needed.

Approximately 80 processors of personal dosimetry use thermoluminescent dosimeters (TLDs). The dosimetry processors be able to measure radiation doses to within +/- 50% of the correct value have focused attention on the reproducibility of the TL elements within each TLD.