Which device is used to measure HVL?

Which device is used to measure HVL?

• A. Dosimeter
• B. Geiger counter
• C. Ionization chamber
• D. Densitometer

Answer: (A)

HVL is found by measuring how much the beam is attenuated as you pass it through increasing thicknesses of a filter, and identifying the thickness that reduces the beam intensity to half. To do this accurately, you need a detector that gives a direct, stable measure of the beam’s exposure (air kerma) as a function of thickness. An ionization chamber provides that precise, real-time exposure reading and has a linear response in the diagnostic X-ray range, making it ideal for HVL measurements. A dosimeter is a general dose-measuring device, but HVL requires exact transmission measurements rather than accumulated dose over time. A Geiger counter is not suitable due to its limited energy response and lower accuracy for this purpose. A densitometer measures film density, not the transmitted beam exposure, so it isn’t used for HVL.

HVL is found by measuring how much the beam is attenuated as you pass it through increasing thicknesses of a filter, and identifying the thickness that reduces the beam intensity to half. To do this accurately, you need a detector that gives a direct, stable measure of the beam’s exposure (air kerma) as a function of thickness. An ionization chamber provides that precise, real-time exposure reading and has a linear response in the diagnostic X-ray range, making it ideal for HVL measurements.

A dosimeter is a general dose-measuring device, but HVL requires exact transmission measurements rather than accumulated dose over time. A Geiger counter is not suitable due to its limited energy response and lower accuracy for this purpose. A densitometer measures film density, not the transmitted beam exposure, so it isn’t used for HVL.