Base physics

Question 1

Coulomb interaction

Answer 1

F=kq1q2/r2

Question 2

Kinetic energy

Answer 2

KE = mc2 – mc02

Question 3

Force on a charged particle in magnetic field

Answer 3

F = qvB 
r = mv/qB

Question 4

Exponential decay of a radioactive isotope

Answer 4

N = N0e-λt 
λ = 0.693/T1/2
N = N0 x 2-t/T1/2
Tavg = 1.44 T1/2

Question 5

Activity

Answer 5

A = N0 λ e-0.693/T1/2 = A0 e-0.693/T1/2 = A0/2t/T1/2

Question 6

Transient equilibrium

Answer 6

Ad=Ap*Tp/(Tp-Td)

Question 7

Secular equilibrium

Answer 7

Ad=Ap

Question 8

Photo electric effect

Answer 8

Eelectron=hv-Ebind

P~(Z/E)^3

Question 9

Compton electron

Answer 9

Eelectron=hv-hv’=hv*a(1-cosx)/(1+a(1-cosx))

Question 10

Compton photon

Answer 10

hv’=hv/(1+a(1-cosx))

Question 11

probability of compton

Answer 11

1/e
~electrondencity
~dencity

Question 12

Compton Scattered photon at 90deg

Answer 12

energy = 0.511 MeV

Question 13

Compton Scattered photon at 180deg

Answer 13

Energy = 255

Question 14

Pair production energy threshold

Answer 14

Energy threshold > 1.022 MeV

Question 15

Pairproduction probability

Answer 15

~Z^2

~ln(E)

Question 16

KERMA

Answer 16

non-stochastic quantity applied to indirectly ionizing radiations = kinetic energy released in matter (per unit mass)

Question 17

CEMA

Answer 17

non-stochastic quantity applicable to directly ionizing radiation (electrons, protons) = converted energy per unit mass

Question 18

TERMA

Answer 18

total energy released in matter

Question 19

Initial dose build-up

Answer 19

Caused by kerma that generates secondary

electrons and releases energy in the medium

Question 20

equivalent square

Answer 20

eq=2ab/(a+b)

Question 21

Tissue-Air Ratio

Answer 21

TAR=Dd/Dfs

Question 22

Back scatter factor

Answer 22

TAR at dmax

Question 23

Scatter-Air Ratio

Answer 23

Used to calculate scattered dose in the medium

SAR=TAR(d,r)-TAR(d,0)

Question 24

Resistance

Answer 24

R=v/I

Question 25

Capacitance

Answer 25

C=q/V

Question 26

inductance

Answer 26

V_L=Ldi/dt