Lec 5 Chest Radiography

Question 1

What is physics of how xray works?

Answer 1

• electrons accelerated in vaccume tube and collide with anode usually tungsten

Question 2

How are characteristic xrays generated?

Answer 2

• high energy electron collides with inner shell electron, both electrons ejected leaving hole in inner layer
• hole filled by outer layer electron

Question 3

How are bremsstrahlung x rays generated

Answer 3

• when electron passes near nucleus it is slowed down and its path is deflected

energy lost is emitted

Question 4

Are most xrays generated characteristic or bremsstrahlung

Answer 4

mostly bremsstrahlung (~80%)

Question 5

What is level of attenuation [absorption] of different tissues?

Answer 5

air < fat < soft tissue < bone < metal

black –> gray –> white

Question 6

What 3 different types of projections?

Answer 6

• frontal posterior-anterior [PA] = requires standing up
• frontal anterior-posterior [AP]
• lateral