1. Concepts you already know!!!
Chapter 8
Concepts you already know!!!

2. INTENSITY = ROENTGENS AKA EXPOSURE
mAs and mGya or mR proportional?
kVp and mGya mR proportional?
Distance and mGya mR proportional?
How do you “harden” the beam
“The disadvantage of x-ray beam filtration is reduced image contrast owing to beam hardening.” Why?

3. HALF VALUE LAYER What is penetrability?
HIGH QUALITY VS LOW QUALITY X-RAYS
HVL See last green box on pg 142

4. FILTRATION Inherent Added Compensating
What affect does added filtration have to HVL?
Compensating

5. Interaction with Matter
Chapter 9
Interaction with Matter

6. INTERACTION WITH MATTER
X-RAYS AND
INTERACTION
WITH
MATTER

7. Low energy
Medium energy
High energy
interact with whole atom
interact with electrons
interact with nuclei

8. Low energy Classical or coherent or Thomson, Rayleigh
interacts with target atom
excites it
DOES NOT IONIZE IT
NO ENERGY TRANSFER
change of direction (scatter) but no ionization
little significance in diagnostic x-ray

9. Medium energy Photoelectric effect lower KvP (atomic #)
inner shell electrons
x-ray totally absorbed
secondary/
characteristic
Produces the brightness (white) on film
useful

10. Medium energy Scattered x-ray can go many directions not useful
Compton Effect
Increases with higher energy
interacts with outer shell electron
IONIZES ATOM
energy divided between scattered x-ray &compton electron
Scattered x-ray can go many directions
not useful
happens with all exams
backscatter

11. High energy Pair production-interaction near the nuclei
Photodisintegration-absorbed by nucleus
1.0 MeV and 10MeV respectively

12. What does all this mean in terms of images on the film?

13. COMPTON VS PHOTOELECTRIC EFFECT
Compton-produces film fog
Photoelectric effect results in no x-rays reaching the film (radioopaque)

14. DIFFERENTIAL ABSORPTION
Difference of those x-rays absorbed photoelectrically and x-rays not absorbed at all.
Radiolucent
<5% reach film
<1/2 which reach film interact
1% of x-rays emitted produce film image

15. WHAT IS MASS DENSITY?

16. Contrast examination
Barium
Iodine
Air

17. Exponential attenuation
X-ray interaction in any of the five mechanisms already note
Which are…
Exponential attenuation (pg 185 figure 12-15