Distortion Visibility Types of Motion - Voluntary & Involuntary

1. GEOMETRIC DETAIL, VISIBILITY AND
DISTORTION OF DETAIL

2. GEOMETRIC DETAIL
A SOURCE TO IMAGE RECEPTOR DISTANCE,
ORIENTATION, THE AMOUNT OF MAGNIFICATION,
AND SIZE OF THE FOCAL SPOT.

3. DISTORTION
INDICATES AN UNDERSIRED CHANGE IN THE SIZE AND
SHAPE OF THE ANATOMIC PART HAS OCCURRED IN
THE PROCESS OF IMAGING THE PART.
MISREPRESENTS THE SIZE AND SHARPE OF THE
OBECT.

4. VISIBILITY
OF THE RECORDED DETAIL, REFERS TO THE BRIGHTNESS
DENSITY OF THE IMAGE ALONG WITH IMAGE CONTRAST.
VISIBILITY OF THE ANATOMIC STRUCTURE AND ACCURACY
OF THE STRUCTURAL LINES RECORDED TO DETERMINE THE
OVER ALL QUALITY OF THE RADIOGRAPHIC IMAGE.

5.  TYPE OF MOTION
✓ VOLUNTARY
✓ INVOLUNTARY
✓ LIMITING MOTION UNSHARPNESS
✓ ADVANTAGES OF MOTION IN RADIOGRAPHY

6. 1. VOLUNTARY MOTION
- PATIENT MOVEMENT OF BODY
-GENERALISED BLURRING OF THE LINKED STRUCTURE,
SUCHAS BLURRING OF THE THORACICBONY AND
TISSUE STRUCTURESAS EVIDENT

7. 2. INVOLUNTARY MOTION
- CARDIAC, PERISTALSIS, SPASM ANDTUMOR
- LOCALISED UNSHARPNESS OR BLURRING
- LESS OBVIOUS BUT CAN BEVISUALISED ON
ABDOMINAL IMAGESAS LOCALISED BLURRING OF THE
BOWELOUTLINES APPEARING SHARP
SENT

8. 3. LIMITING MOTION UNSHARPNESS
MOTION UNSHARPNESS IS CAUSED BY MOVEMENT OF THE
PATIENT, THE DETECTOR OR THE SOURCE OF X-RAYS,
DURING THE EXPOSURE. MOVEMENT OF THE PATIENT,
EITHER VOLUNTARY OR OTHERWISE, IS THE MOST COMMON
CAUSE AND THIS CAN BE MINIMISED IN A NUMBER OF WAYS:
IMMOBILIZING THE PATIENT, ASKING THE PATIENT TO KEEP
STILL OR TO HOLD THE BREATH AND KEEPING EXPOSURE
TIME SHORT, AND THEREBY GIVING THEM LESS TIME IN
WHICH TO MOVE, ARE THE MOST OBVIOUS.

9. 4. ADVANTAGE OF MOTION IN RADIOGRAPHY
THE ABILITY TO MEASURE SKELETAL MOTIONS IS A
KEY ASPECT TO ONE'S UNDERSTANDING OF
VERTEBRATE BIOMECHANICS, ENERGETICS, AND
MOTOR CONTROL.

10. EFFECT OF THE FOCAL SPOT SIZE TO RADIOGRAPHIC
DEFINITION
THIS DIAGRAM ILLUSTRATES THAT LARGER FOCAL SPOT SIZES INCREASE PENUMBRAL
UNSHARPNESS..

12. OBJECT TO FILM DISTANCE

13. OFD
• is the distance between the
radiation side of the test
object and the film surface,
measured along the central
axis of the radiation beam.

14. FOCAL TO FILM DISTANCE

15. FFD
• is the the distance between the
center of the anode of the x-ray
tube (the focal spot) and the film
(top of cassette). Also known as,
Source-image distance (SID) which
this measurement effects
magnification, distortion, and x-ray
beam intensity.

16. INTENSIFYINGSCREEN SPEED

17. INTENSIFYINGSCREENSPEED
• Detail (fine): A very slow system seldom used in
modern radiography, used by Podiatrists in some
instances. It has a relative speed of 50 when
used with Hi Speed Blue Film. Medium: Twice
the relative speed of Detail (100), and like Detail,
seldom used today.

18. FILM SCREEN CONTACT

19. FILM SCREENCONTACT
• Improper contact of the film screen may cause
blur and magnification. Screens are composed
of a base and emulsion layer that is made of
Gelatin and silver halide crystals (Bushong,
2013). X-rays interact with silver halide to
create light evenly dispersed throughout the
surface of the film.

20. TUBE - OBJECT- FILM ALIGNMENT

21. TUBE-OBJECT-FILM ALIGNMENT
• Alignment helps control geometric distortion and
grid cutoff, resulting in more consistent
radiographic image quality. While there is some
variability in the implementation of these tools,
most systems essentially operate in a similar way.
Operators are able to choose between tabletop
and bucky exposures.

22. END.