2. Production of Electromagnetic
waves
When a charged particle is accelerated:
Electromagnetic wave / stream of photons
(Bremmstrahhung radiation/ braking) is produced
The larger the acceleration or deceleration of charged
particle, the higher is frequency (or lower the
wavelength) of penetration of the produced e-m waves
or emitted photons
3. Production of X-rays: High
frequency e-m waves / photons
X-Ray photons are produced by:
Bombarding high speed cathode rays (beam of
electrons) against a mental target
Cause of production
Sudden stoppage and change in direction of the
beam of electrons / cathode rays which is nothing
but a very large deceleration /retardation
Note: A lot of thermal energy / heat is also produced in
the process
4. Diagram of X-Ray Tube
Diagram with numbered parts Label for the parts
1. Evacuated glass envelope
2. Low voltage source
3. Heated filament as cathode
4. X-ray window
5. Cooled metallic anode
6. Target metal
7. High voltage source
8. Cathode rays
9. X-rays
5. X-Ray spectrum: Variation in X-ray
wavelengths
Spectrum description
Curve for typical wave length
variation
Two typical X-Ray spectrum
components
Continuous distribution
accelerating cathode rays of
wavelengths interrupted by
line spectrum of target metal
Two sharp cut-offs at short
wavelength side of spectrum
as line spectrum of target
metal
Sharp spectrum cut-offs
produce X-Rays
6. Applied formula for cut-off
wavelength of X-rays
Cut-off wavelength of X-rays is given by the following
formula
hc/eV
Where
h is Plank’s constant
c is velocity of light
e is charge on electron
V is PD across electrodes
7. Diagram of X-ray image formation
Numbered Diagram Labels for parts
1. Beam of X-rays
2. Soft tissues
3. Bone
4. X-ray film
5. Developed film parts
a. White for the bone
b. Dark or black for the bone
8. Absorption and penetration of X-
rays through human body
Barium meal is given for investigating stomach
ailments
Barium sulphate is a good absorber of X-rays to give a
clear image of the stomach
By injecting a radio-opaque dye into the into the
blood stream, blood vessels can be imaged on X-ray
film
9. X-rays imaging of bones
Curve: A common X-ray spectrum parts
X-axis: wavelength
Y-axis: Intensity of X-rays
Peak-1 as line spectrum of
target
Peak-2 as line spectrum of
target
Note : cut-off wavelength formula
of X-rays
hc/eV
10. Attenuation (change of intensity) of X-rays for diagnosis
Attenuation Curve Application
Principle: When X-rays pass
through a medium, their
intensity is reduced
The %age of intensity
transmitted with thick has the
typical curve
It has been seen that same
thickness produces half of the
variation of intensity
With a parallel beam, linear
attenuation coefficient of tissues
is calculated for diagnostic
purposes
Formula is given on the curve
