compton

Question 1

how does compton happen?

Answer 1

x ray comes in and gives up part of energy to electron

electron ejected

x ray carries on with less energy and in a different direction (scattered)

energy of photon divided between scattered photon and secondary electron

electron will interact with other tissue

scattered photon ultimately absorbed photoelectrically

Question 2

compton facts

Answer 2

dependant on electron density

4-12MeV

changes direction and reduces energy

kinetic energy of scattered x ray is equal to difference between the energy of the incidence x ray and the energy imparted to the electron

occurs with outer shell loosely bound electrons

doesnt differentiate well between bone and soft tissue

Question 3

importance of angle of deflection

Answer 3

any direction

0- no energy loss

180 - energy transferred to electron

forward scatter at high energies as low angle events happen

Question 4

3 things that happen as x ray energy increases

Answer 4

increases penetration through tissue without interaction

increased compton relative to pee

reduced total compton scatter

Question 5

what happens as atomic no of absorber increases

Answer 5

no effect

Question 6

what happens as mass density of absorber increases

Answer 6

proportional increase in compton scatter

Question 7

advantages of compton

Answer 7

higher energy

greater penetration

less dose disappearing to side

all absorbed even if travelling through bone