Which interaction primarily produces the continuous spectrum in diagnostic x-ray beams?

• A. Bremsstrahlung
• B. Compton
• C. Photoelectric
• D. Characteristic

Answer: (A)

The wide, continuous x-ray spectrum in diagnostic beams comes from Bremsstrahlung. When fast electrons collide with the target nuclei, they slow down due to the strong electric field and emit photons in the process. Each deceleration event can release a photon with a different energy, so the emitted photons fill a broad range from near zero up to about the electron’s initial energy (the tube potential). That variety creates a smooth, continuous spectrum.

The other interactions don’t produce this broad beam. Characteristic radiation results in photons with specific, discrete energies tied to the target atoms’ electron energy levels. The photoelectric effect similarly leads to absorption and characteristic emission rather than a continuous range. Compton scattering changes photon energy after interaction and mainly contributes to scattered radiation rather than forming the primary continuous beam.