Radiation Physics & Principles Flashcards

What is the approximate threshold kVp at which pair production becomes possible?

Answer: 1,022 kVp (equivalent to 1.02 MeV)

Pair production requires a minimum photon energy of 1.02 MeV (equivalent to ~1,022 kVp), far above diagnostic imaging ranges.

Which material is most commonly used as the target (anode) in a diagnostic x-ray tube?

Answer: Tungsten

Tungsten is used as the anode target because of its high atomic number, high melting point, and high thermal conductivity.

What does the effective atomic number (Z) of a material indicate in radiography?

Answer: The material's ability to attenuate x-rays

The effective atomic number indicates how strongly a material will attenuate x-rays; higher Z materials attenuate more at diagnostic energies.

Which interaction is responsible for the majority of patient radiation dose in diagnostic radiography?

Answer: Photoelectric effect

The photoelectric effect results in complete absorption of photon energy by tissue, making it the primary contributor to patient dose.

As kVp increases in diagnostic radiography, what generally happens to patient dose?

Answer: Patient dose decreases because higher energy photons penetrate more efficiently

Higher kVp photons penetrate tissue more efficiently (more Compton scatter, less photoelectric effect), reducing overall patient dose when mAs is adjusted accordingly.

What is the purpose of the rotating anode in a diagnostic x-ray tube?

Answer: To distribute heat over a larger target area

The rotating anode spreads heat over a larger surface area of the anode disc, allowing higher heat loading without damage.