Electromagnetic radiation consists of energy in
small packets called photons.
They are grouped according to there wave
length and frequency.
Properties of x-rays
radiations composed of
small packets of energy
Travel at speed of light.
Travel in straight lines.
protons in nucleus.
Neutrons of no charge
also in the nucleus.
electrons in various
orbits around the
Lighter elements have fewer number of protons
such as oxygen.
Heavier elements have more such as lead.
The number of protons is called the atomic
Density of matter.
Low density matter is loosely packed with large
spaces between each atom like air.
High density matter is tightly packed with atoms
sitting close to each other like lead.
Production of radiograph
X-ray are produced in the machine.
X-ray interact with the patient.
Image is recorded in the x-ray plate.
Production of the x-ray
radiations on the
The x-ray tube.
The tube head consists of a pair of electrodes.
- A negatively charged cathode with
include a heater filaments.
- A positively charged a node with a
Steps in x-ray production.
Filament is heated and gives off cloud of
A large electrical charge is placed in the
cathode/anode space causing the electrons to
race toward the anode.
When they crush into the anode it causes x-ray
to be given off.
X-ray machine components.
The tube head where the x-rays are generated.
The control panel which regulate the strength
and amount of the x-rays produced and trigger
The power supply which provide the energy to
creates the x-rays.
X-ray tube head
Found in smaller
The target is fixed in
block of copper.
Only capable of low
mA to 30
Found in large machines.
The target is rotate in
mA up to 300
The control panel.
The three factors that can be varied during
producing radiograph are
The kilovoltage (KV) difference applied between
the anode and cathode during exposure.
The milliamperage (mA) applied to the filament.
The duration of exposure.
Higher kv attract the electrons toward the anode by
They smash the anode harder and produce x-ray with
higher energy and greater tissue penetrating power.
Increasing mA increase the number of electrons cloud
around the filament. Result in higher number of x-ray
produced per second.
As an x-ray beam leave the tube head, it fans out
and become weaker.
As the distance double, the strength is reduced.
Formation of the image
The distance from the anode target to the film is
called the film focal distance.
Changing the distance affect the quantity of the
x-ray reaching the film.
Increasing the distance means that less x-rays
reaches the film.
Formation of image
Low density or low
atomic number tissues
allow more x-rays
through causing more
blackening of film.
High density or high
atomic number tissues
allow less x-ray through
causing less blackening
of the film.
Effect of kilovoltage.
Increasing kV, increases the penetrating ability
of the x-rays photons.
More x-ray photons get through to darken film.
High kv produces darker images but poor
Effect of milliamperage and time.
Increasing the mA and mAs, increases the
number of x-rays production.
It does not affect the penetrating power of the
Increase mA will increase overall blackness of
X-ray film composition.
Polyester base that provide support has bluish
Film emulsion is a thin layer of chemicals
coating the base composed of.
- Light sensitive silver halide (mainly Bromide
- gelatins that keep the silver bromide grains
When x-ray hits the atoms in the film emulsion
it causes it to change leaving a latent (hidden),
The cassette film
Light proof container for film.
Lead backed to absorb transmitted radiations
and prevent scatter.
Intensifiers to use lower exposure.
Composed of hundreds of alternating thin lead
strips with aluminum or fiber interspaces.
X-ray can pass through the interspaces without
Lead strips absorb weak energy scatter x-ray that
Strips is encased in protective cover.