Radiography
Introduction
Objectives
To describe
 Properties of x-rays
 Production of x-rays
 Formation of radiographic image
 Components of an x-ray room
 The projections
 The radiographic technique
What are x-rays?
 Kind of
electromagnetic
radiation
 Means of
propagation of
energy
Nature of x-rays
 Two theories to describe the nature
1. Wave theory (Propagate as waves)
C = f λ ; Speed = frequency x wavelength
2. Corpuscular theory (Involved in
interactions as particles)
E=hf;
Photon Energy = Plank’s constant x
Frequency
Properties/Characteristics of EM
Radiation
 Common properties
 Properties Specific to x-rays
Characteristics of X-Rays
1. X-rays are invisible.
2. X-rays are electrically neutral. They have neither
a positive nor a negative charge.
3. They cannot be accelerated or made to change
direction by a magnet or electrical field.
4. X-rays have no mass.
5. X-rays travel at the speed of light in a vacuum.
6. X-rays cannot be optically focused.
7. X-rays form a polyenergetic or heterogenous
beam.
8. The x-ray beam used in diagnostic radiography
comprises many photons that have many
different energies.
9. X-rays travel in straight lines.
10. X-rays can cause some substances to fluoresce.
11. X-rays cause chemical changes to occur in
radiographic and photographic film.
12. X-rays can be absorbed or scattered by tissues
in the human body.
13. X-rays can produce secondary radiation.
14. X-rays can cause chemical and biologic damage
to living tissue.
Properties
1.
2.
3.
4.
&
Rectilinear propagation
Penetration ability
Differential absorption
Fluorescent effect
5. Photographic effect
6. Ionization of medium
7. Biological effects
uses of x-rays
1.
2.
3.
4.
Prediction of the path
Basis of radiography
Tissue differentiation
Intensification of image
& fluoroscopy
5. Image recording on
photographic emulsions
(films)
6. Detection &
measurement of
radiation
7. Radiotherapy & Need for
radiation protection
Production of X-rays
X-rays are produced in an X-Ray tube by
two processes:
1. Deceleration of fast moving electrons
either by stopping, reducing speed or by
changing its direction
2. The transfer of an electron between two
inner orbits of an atom
Target of an X-ray tube
(Continuous spectrum)
Characteristic radiation
Lay out of an X-ray room
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Tap and sink
Hand gel
Detergent wipes
Soap and towel dispenser
Vomit bowels
Latex gloves / non latex gloves for those
with allergies
Equipment needed for IVPs
General waste bin
Sharps bin
Emergency resuscitation mask/oxygen
connectors
Oxygen outlet
Suction outlet
13.
14.
15.
16.
17.
18.
19.
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21.
22.
23.
24.
X-ray table
Overhead x-ray tube
Lead gowns
Moveable seat for patient positioning
Long leg x-ray film holder
Wall bucky
Arm extension for vertical bucky
External film holder
Contrast warmer
Filters for x-ray tube
Positioning Aids
Lead shielding
Principle of Image formation
 X-ray beam of uniform intensity falls on
object consists of structures with different
absorption properties.
 It attenuates in different amounts by different
structures
 The transmitted beam consists of different
intensities – called the ‘aerial image’
 The aerial image falls on the image receptor,
usually on a cassette containing x-ray film
& intensifying screens
X-ray tube
Plot of incident x-ray
beam intensity
Object
Invisible x-ray
image
Plot of transmitted x-ray
beam intensity
Invisible x-ray image
kV mA Sec FFD
E
B
B1
EM
E
B1
Supporting tissue (m)
B2
E
B2
T2
T1
ET1
EM
T3
Air
Invisible
X-ray
image
consists
of
different xray
intensities
ET2
ET3
EA
Focal spot
X-ray beam
Cross section
Plot of x-ray
intensities
Radiographic projections
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AP
PA
Lateral
Obliques:- RAO, LAO, RPO, LPO
Decubitus (patient lying down and the x-ray
beam horizontal)
Description of Techniques
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Position of patient
Position of body part
Position of cassette related to body part
Direction and centre of x-ray beam
Breathing status
Exposure factors
Radiographic appearance - criteria
Conclusion
 The accuracy of diagnosis depends on the
quality of the Image.
 The radiographic image should have,
– Optimum contrast
– High resolution
– Minimum unsharpness
– Less noise
– No artefacts
– High definition
END
Thank you