2. Chapter 9 Concepts you already know!!!

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

4. HALF VALUE LAYER l What is penetrability? l HIGH QUALITY VS LOW QUALITY X-RAYS l HVL See last green box on pg 155

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

6. Chapter 10 Interaction with Matter

7. X-RAYS AND INTERACTION WITH MATTER

8. l Low energy l Medium energy l High energy l interact with whole atom l interact with electrons l interact with nuclei

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

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

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

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

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

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

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

16. WHAT IS MASS DENSITY?

17. Contrast examination l Barium l Iodine l Air

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