Radiation Physics for Imaging: X-ray Production, Decay Processes, and Image Quality

RADIATION PHYSICS FOR IMAGING
NAME OF THE STUDENT
INSTITUION

QUESTION 1.
a)
(Fig 1. Bremsstrahlung Radiation)
(PhysicsOpenLab. (2018). Bremsstrahlung Radiation - PhysicsOpenLab. [online])
Continuous x-ray production require 3 basic things
i) A source of electrons through thermionic emission
ii) A means of accelerating the electrons (kVp)
iii) A means of decelerating the electrons produced.
Continuous x-ray production happens at the x-ray tube where the electrons are
produced at the cathode end filament. A current running through the filament

causes it to become extremely hot triggering the cathode filament to produce free
electrons, a process known as thermionic emission (Bushong, 2013, p. 107).
A current (kVp) is then passed through the electrons that gives them high kinetic
energy creating a high negatively charged electrons. This high voltage forces the
electrons through the x-ray tube.
The highly negatively charged electrons slams to the anode end of the x-ray tube
where they are decelerated. In the process of deceleration, they releases their
energy in heat form and most importantly x-rays (Meredith and Massey, 2013, p.
45).
Increase in voltage at the cathode increases the amount of electrons produced and
therefore increases the amount of x-ray (Bushong, 2013, p. 315). However,
increase in the kVp increases the energy of the electron and therefore increases the
energy of the x-rays.
b) Characteristic x-rays are called like this because the energy of radiation is
characteristic of each element in the period table. This means if you measure the
wavelength you can deduce the element that is sending out this radiation (Bushong,
2013, p. 279). In characteristic radiation, an outer electron fills an inner vacancy.
When a high energy electron is passed through the element, it ejects out one of the

atoms in the inner shells. This triggers atom from the outer shell to move to the
vacant space in the inner shell so as to stabilize the element. As a result, there is an
energy difference which results to production of x-rays. The amount of x-ray
produced can be known by calculating the energy difference between the inner a
shell and the displaced outer shell (Bushong, 2013, p. 270).
(Fig 2. X-ray)
Accessed from:
http://whs.wsd.wednet.edu/Faculty/Busse/MathHomePage/busseclasses/
radiationphysics/lecturenotes/bushong/chapter12/lecturenotes12b.html