What test device is used for HVL measurement?

• A. Dosimeter
• B. Ionization chamber
• C. Geiger counter
• D. Film badge

Answer: (A)

For HVL measurement you need to quantify how the beam’s intensity is reduced as you insert a known thickness of absorber and read that reduction accurately in real time. An ionization chamber provides a direct, calibrated readout of the beam’s exposure (air kerma) as you change the absorber thickness. That real-time, linear response across the range used in HVL tests makes it the best choice. A dosimeter is a broad term and might refer to different detectors, but the ionization chamber is the type specifically well-suited for measuring transmitted beam intensity and calculating HVL. Geiger counters are not ideal for HVL because their response isn’t suitable for precise, dosimetric measurements over the required energy range, and film badges are passive and require processing, which isn’t practical for HVL experiments.