Which dosimeter stores dose using phosphor crystals?

Which dosimeter stores dose using phosphor crystals?

• A. Ionization chamber
• B. Film badge
• C. Thermoluminescent dosimeter
• D. Geiger-Muller counter

Answer: (C)

The concept here is storage of absorbed radiation dose in a solid-state material that can later be read out. A thermoluminescent dosimeter uses phosphor crystals (for example LiF doped with Mg and Ti) to store energy from ionizing radiation. When exposure happens, some electrons get trapped in defect sites in the crystal lattice. The amount of trapped energy is proportional to the dose received. Later, heating the crystal releases that stored energy as light—the brighter the glow, the greater the dose. This light is measured to determine the absorbed dose. This is why thermoluminescent dosimeters are the best choice: they specifically store dose information in the phosphor crystals and require a readout by heating to release the light signal. Other options don’t store dose in this way: an ionization chamber measures current produced by ion pairs in air, a film badge records exposure by a chemical change in the film, and a Geiger-Müller counter detects radiation events without storing dose information.

The concept here is storage of absorbed radiation dose in a solid-state material that can later be read out. A thermoluminescent dosimeter uses phosphor crystals (for example LiF doped with Mg and Ti) to store energy from ionizing radiation. When exposure happens, some electrons get trapped in defect sites in the crystal lattice. The amount of trapped energy is proportional to the dose received. Later, heating the crystal releases that stored energy as light—the brighter the glow, the greater the dose. This light is measured to determine the absorbed dose.

This is why thermoluminescent dosimeters are the best choice: they specifically store dose information in the phosphor crystals and require a readout by heating to release the light signal. Other options don’t store dose in this way: an ionization chamber measures current produced by ion pairs in air, a film badge records exposure by a chemical change in the film, and a Geiger-Müller counter detects radiation events without storing dose information.