Radiologic Technologist Practice Exam

What happens to the emission spectrum when kVp is increased from 60 to 68?

1. Increased energy of characteristic photons

2. An increase in the number of characteristic photons

3. Increased quantity of bremsstrahlung photons

4. A leftward shift of the emission spectrum

The correct answer is: Increased quantity of bremsstrahlung photons

Increasing kVp (kilovoltage peak) from 60 to 68 has a significant effect on the emission spectrum, particularly in terms of bremsstrahlung radiation. When kVp is increased, the energy of the photons produced by bremsstrahlung radiation also increases. This is because the higher energy electrons interact with the target material more effectively, resulting in a greater production of high-energy photons. As the energy increases, there is also an increase in the quantity of bremsstrahlung photons emitted. This is due to a greater number of electrons having enough energy to overcome the binding energies of the target atoms, leading to the production of more radiation overall. Therefore, the emission spectrum shows an increase in the quantity of bremsstrahlung photons, producing a broader and more intense continuous spectrum. While it's true that the energy of characteristic photons is directly related to the difference in energy levels of the target material, the question specifically addresses the overall changes in the emission spectrum resulting from an increase in kVp. This increase primarily enhances the quantity of bremsstrahlung, which dominates the spectrum at higher kVps. Thus, the selected answer accurately reflects the primary outcome of increasing the kVp in this scenario.