Nov 2013 radiographic exposure and processing technique sp tyagi

2. Non-recurring:
(a)Basic portable X-ray machine
(b)X-ray protection devices (e.g. lead aprons,
Gloves, Goggles)
(c)X-ray monitoring badges
(d)X-ray film storage box
(e)Different sized X-ray film cassettes (e.g. 8X10”,
10X12”, 12X15” etc)
(f)Different types Grid (e.g. 5:1, 8:1, 12:1 as per grid
ratio)
(g)Different sized X-ray film hangers (At least 4 per
size)
(h)Different sized lead blockers
(i)Lead markers (e.g. Alphabets and numbers)
(j)Animal positioning devices
(k)Safe lights (Usually low wattage red lights)
(l)Film processing tanks
(m)Film drier
(n)X-ray film viewer/illumination box
(o)X-ray record keeping files
Recurring:
(a)Different sized X-ray films
(b)X-ray film developer, replenisher
and fixing agents.
(c)Intensifying screen cleaning
solution
(d)Contrast media
(e)Tranquilizers/sedatives
(f)Anaesthetic agents
(g)Emergency drugs/items stock
(h)Animal restraining basic devices

3. Fixed type: Ceiling suspended or floor mounted Mobile type
Portable type Ultra portable (Dental)

4. Fluoroscopy CT
Digital radiographyPlain and computed radiography

5. X-ray cassettesX-ray cassettes X-ray gridsX-ray grids
X-ray films in light-proof boxesX-ray films in light-proof boxes
Lead markersLead markers

7. X-ray automatic processorX-ray automatic processor
X-ray processing tanks
Dry imager and printer

8. X-rays may be
produced
when a beam
of electrons of
sufficient
energy from
cathode
interact with
anode matter
inside the X-
ray tube.

10. The heat of cathode filament is directly proportional to the magnitude of the current
beam (mA) passed through it.
Thus more is the ma, the more will be the heat and more will be the number of electrons
released from filament atoms.
The more is the number of available electrons to interact with the target, more will be
number of X-rays produced
Another way to control the number of electrons is to increase the time for which machine is
operated. This is controlled by another knob on the control dial which select the time (S).
The kinetic energy of electrons travelling from cathode to anode in the X-ray tube is
dependent on the applied KVP.
The higher is the KVP, the higher will be energy of electrons and
The higher is the energy of incoming electrons, the higher will be the energy of resulting
X-ray photons.

11.  X-rays are directed for a brief period of time in a defined angle towards the
body part to be examined radiographically.
 An X-ray sensitive film in a light proof cassette is kept on the other side of part
to catch those X-rays that are able to penetrate the part.

12.  The X-rays are differentially absorbed in body
tissues through an interaction known as
photoelectric absorption.
 Thus its primary beam gets attenuated and
reach the X-ray film carrying useful
information about the composition of the body
part exposed.
X ray film in light-proof cassette
AirAir
Bon
e
Bon
e
Soft
tissue
• Highest
absorption
• Intermediate
absorption
• Lowest
absorption

13.  The X-ray film gets selectively modified by these X-rays*
depending upon the number of X-rays reaching to its
different parts thus forming a ‘LATENT IMAGE’ of the
part being exposed.
 *X-ray films are in fact mostly exposed by the light rays
emitted by the intensifying screen fitted inside the cassette.
(The intensifying screen convert X-rays in to light.)

15.  Such modified X-ray film can be chemically processed
to convert this latent image in to a visible one.
 The parts of AgBr grains where metallic silver atoms
have been deposited is more vulnerable to the action
of reducing solution.
 Here the Ag ions readily acquire electrons from the
developing solution and converts in to black metallic
silver.
 In the fixing and clearing solution, the part of emulsion
containing metallic silver is fixed and unaffected AgBr
grains are solubilized and removed.

16.  Thus area of X-ray film receiving greater number of X-rays
(or light rays) turn blacker than other; the area of film not
receiving the X-rays turns transparent.
 When viewed against white light, the transparent area
appears white.
 Accordingly a grayish image forms over radiograph
depicting the details of the section of the part exposed.
Thus on a radiograph bone looks whitish, lungs
look blackish and the rest of the soft tissue
appears in shades of gray.

19.  Minimum magnification of the image of structures being examined (FFD
and subject film distance)
 Least possible distortion of the same (Patient positioning and X ray beam angles)
 Sharp delineation of the structures (kVp, mAs, patient restraining, use of grid,
processing of film)
 Adequate contrast (kVp, mAs, processing of film)
 Sufficient radiographic density (kVp, mAs, processing of film)
 Necessary numbers of radiographic views
 Additionally required contrast techniques
 Absence of radiographic artifacts and processing faults (Quality of X ray
accessories, processing and storage of films)

21. Formulation of radiographic technique chartFormulation of radiographic technique chart
Thickness of part (X)
in cms
Suggestive kVp
Up to 80 kVp 80-100 kVp Above 100 kVp
X-3 A-6 A-9 A-12
X-2 A-4 A-6 A-8
X-1 A-2 A-3 A-4
X A A A
X+1 A+2 A+3 A+4
X+2 A+4 A+6 A+8
X+3 A+6 A+9 A+12
• *A is the kVp that provided best radiographic quality on trial exposures.
• ** Mas is to kept constant as per the best combination on trial exposures
• *** This technique chart will be applicable for similar kind of tissues only.

22. kVp change required with change in mAskVp change required with change in mAs
kVp range kVp change required when mAs is doubled or halved
Doubled Halved
41-50 -4 +4
51-60 -6 +6
61-70 -8 +8
71-80 -10 +10
81-90 -12 +12
91-100 -14 +14
101-110 -16 +16
mAs change required with use of grid
Grid ratio Increase required in mAs by a factor of
5:1 2
8:1 3
12:1 4

23. Exposure latitudeExposure latitude
kVp
range
Exposure latitude
46-55 ±2 kVp
56-65 ±4 kVp
66-75 ±6 kVp
76-85 ±8 kVp
86-95 ±10 kVp
Degree of
variation from the
correct exposure
factors that still
produces a
diagnostic
radiograph.
Degree of
variation from the
correct exposure
factors that still
produces a
diagnostic
radiograph.
Thumb rules
•Use higher kVp
•Use highest possible mA
•Use shortest possible exposure time (s)
•Use constant FFD (90-100 cms.)

24. Processing solution tanks
A: Developing solution tank
B: Rinsing solution tank
C: Fixing solution tank
D: Washing (running water)
tank
E: All enclosing warm water
(~200
C) tank
Processing solution tanks
A: Developing solution tank
B: Rinsing solution tank
C: Fixing solution tank
D: Washing (running water)
tank
E: All enclosing warm water
(~200
C) tank
Off to drierOff to drier
BA C DE
5 min5 min
1/2 min1/2 min
10 min10 min
20 min20 min
Timings are suggestive
only

25. 12 mAs, 16 mAs, 20 mAs, 24 mAs kVp constant at 7512 mAs, 16 mAs, 20 mAs, 24 mAs kVp constant at 75