1.2 X-ray Interaction

Question 1

photoelectric nobel prize

Answer 1

Einstein-1921

Question 2

Compton shared nobel with

Answer 2

1 more person in 1927

Question 3

attenuation means

Answer 3

gradual loss of intensity

Question 4

attenuation can be caused by

Answer 4

absorption
coherent or incoherent scattering
reflection
refraction

Question 5

attenuation coef depends on

Answer 5

material (density and composition)
incoming x-ray energy

Question 6

lambert-beer law states

Answer 6

attenuation as a function of thickness and att coeff
N(x) = N0 exp(-mu x)

Question 7

mu in lambert-beer law is

Answer 7

Ro times delta
atomic density * cross section

Question 8

mu depends on 3 things

Answer 8

energy
atomic number z
mass density

Question 9

which event mostly happens at inner / outer shell respectively

Answer 9

photoelectric: inner

compton: outer

Question 10

full energy loss: ?

partial energy loss: ?

no energy loss: ?

Answer 10

photoelectric

compton - incoherent

thompson scattering - coherent

Question 11

mu = ? + ? + ?

Answer 11

mu = tau + delta + kappa
att coef /// photoelectric /// compton /// pair production

Question 12

photoelectric triggers two process

Answer 12

1 characteristic x-ray
2 photoelectron

Question 13

photoelectrons kinetic energy is equal to

Answer 13

incoming photon energy - binding anergy

Question 14

mass att coefficient is proportional to

Answer 14

1/E^3 : incoming photon xray

z^3: atomic number

Question 15

max energy transfer in compton happens at

Answer 15

180 degrees, backscattering, photon goes to where it comes from

Question 16

probability of compton depends on

Answer 16

scattering angle and incoming photon energy

Question 17

scattering angle probability given by

Answer 17

klein-nishima equation

Question 18

threshold energy for pair production

Answer 18

> 2 emc^2
1.022 MeV minimum

Question 19

for higher domination by photoelectric efefct, one needs to change

Answer 19

higher atom number required

Question 20

30-40 kVp
50-100 kVp
80-120 kVp
which modalities

Answer 20

mammograpghy
angiography
computed tomography