Fundamentals of Imaging This course will provide you with the principles involved in the formation and recording of the radiologic image in both conventional and digital imaging systems as well as the principles of image quality assessment. Geometric factors - focal spot size

1. FUNDAMENTAL
S OF IMAGING
RAD 206
Geometric factors

3. What is focal spot?
and
What is effective focal spot ?

6. The smaller the beam
towards the patient
The better the detail of
image produced

8. FOCAL-SPOT BLUR
Dependent on the size of the effective
focal spot
Smaller the effective focal spot results
in:
•less Blur and
•better spatial resolution
Focal spot Blur is the most important
factor in determining spatial resolution

9. Smaller x-ray beam width will produce a
sharper image
Fine detail = small focal spot ( for small parts
of the body )
General radiography of large areas uses large
focal spot
Experiment and compare between beam from
a penlight with a beam from a flood light

10. Focal-Spot Blur is
caused by the
effective size of the
focal spot, which is
larger towards the
cathode side of the
image
Anode cathode

11. Effect of focal
spot size on:
Penumbra
And
Resolution

12. Anode cathode

13. Focal Spot Blur is
smaller when the OID
is smaller

14. OBJECT SHAPE
Objects with structures coincide
(aligned) with the x-ray beam has
maximum detail