X-ray energy spectrum - DOE-HDBK-1141-2001

Radiological Assessor Training

DOE-HDBK-1141-2001

Instructor's Guide

When electrons strike and excite target atoms,

When the accelerated electrons

simply decelerate (brake) as they

the kinetic energy of the electrons is deposited in

come near the large, positively

the target as heat. When electrons ionize target

charged nucleus of a target atom, the

atoms, characteristic x-rays will be emitted as

change in energy resulting from the

electrons from outer shells fill vacancies created

deceleration is emitted as a

by ejected electrons.

bremsstrahlung photon. If the

accelerated electron loses all of its

energy and essentially comes to rest,

then the energy of the bremsstrahlung

photon will be equal to the initial

kinetic energy of the electron.

Show OT 12.6.

B. X-ray energy spectrum

Bremsstrahlung is German for

The energy of the x-ray photons coming out of

"braking radiation."

the x-ray machine is of interest to the users of

the machine. The typical energy spectrum from

an x-ray machine consists of the characteristic x-

rays from the target, which have discrete

energies, and the bremsstrahlung photons which

have a whole range of energies, the maximum

energy depending on the potential difference

across the tube. For a typical x-ray machine, the

bremsstrahlung photons far outnumber the

characteristic x-rays.

Module 12 5