At what voltage is Characteristic radiation produced in dental x-ray machines?

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Multiple Choice

At what voltage is Characteristic radiation produced in dental x-ray machines?

Characteristic radiation happens when incoming electrons have enough energy to eject an inner-shell electron from the target atom. For a tungsten target, the energy needed to knock out a K-shell electron is about 69.5 keV. So the tube must be operated at around 70 kV or higher to enable inner-shell ionization. Once that threshold is reached, vacancies are filled by electrons from higher shells, emitting photons with energies specific to tungsten. If the voltage is below about 70 kV, inner-shell ionization doesn’t occur, and only bremsstrahlung (a continuous spectrum) is produced.

Characteristic radiation happens when incoming electrons have enough energy to eject an inner-shell electron from the target atom. For a tungsten target, the energy needed to knock out a K-shell electron is about 69.5 keV. So the tube must be operated at around 70 kV or higher to enable inner-shell ionization. Once that threshold is reached, vacancies are filled by electrons from higher shells, emitting photons with energies specific to tungsten. If the voltage is below about 70 kV, inner-shell ionization doesn’t occur, and only bremsstrahlung (a continuous spectrum) is produced.

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