Chapter 2: Interactions of Radiation with Matter

Question 1

Sigma is the ____________ which describes the probability of interaction in a certain area.

Answer 1

interaction cross section

Question 2

Lambert-Beer law describes ____________ in _________.

Answer 2

radiation attenuation/absorption
homogenous solutions

Question 3

The molar extinction coefficient for strong absorbers is around _________.

Answer 3

10^4 M-1 cm-1

Question 4

The two attenuation coefficients for radiation dosimetry are _________ and __________.

Answer 4

energy transfer coefficient
energy absorption coefficient

Question 5

Etr is _____________.
Eab is _____________.
Typically Eab ____ Etr.

Answer 5

average energy transferred to charged particles in the matter
average energy absorbed by the charged particles in the matter.
<=

Question 6

Attenuation can occur due to a number of processes such as _________ or _________.

Answer 6

absorption
scattering

Question 7

The probability/cross section for each interaction depends on ____________ and __________.

Answer 7

energy of the photon, given by hv
atomic number of attenuator

Question 8

The four types of photon interaction are ____________, ____________, ____________, and _____________.

Answer 8

coherent/elastic scattering
non-ionizing interaction
ionizing interactions
photonuclear effects

Question 9

________________ has no biological radiation effects and makes up less than a couple % of the total attenuation coefficient.
____________ is also minor.

Answer 9

coherent/elastic scattering
photonuclear effects

Question 10

____________ is a type of non-ionizing interaction.
__________, _____________, __________ are types of ionizing interactions.

Answer 10

Excitation
Photoelectric effect, Compton scattering effect, Pair production

Question 11

The three types of transitions for absorption of energy by a molecule are __________, __________ and __________.

Answer 11

electronic, vibrational and rotational

Question 12

Electronic transitions have energy ________ and result in ___________.
Vibrational transitions have energy ________ and result in ___________.
Rotational transitions have energy ________ and result in ___________.

Answer 12

1.7-10.8 eV
visual/ultraviolet light waves
0.04-0.4 eV
infrared light waves
0-0.04 eV
microwaves

Question 13

1 eV = _________ J
1 cal = _______ J

Answer 13

1.6 x 10^-19
4.18

Question 14

For ionizing interactions, the process by which x-ray photons are absorbed depends on __________ and __________.

Answer 14

energy of photons
chemical composition of absorbing material

Question 15

Ionizing photon interactions have _______ transmission through thick material, are ________ ionizing and for higher energy have __________ penetration.

Answer 15

good
indirectly
higher

Question 16

__________ is when a photon ejects an electron from an atom and all the photons energy is absorbed by the atom to remove the electron from its shell. The photon _________.

Answer 16

photoelectric effect
ceases to exist

Question 17

A ________ is a particle of EM radiation with no mass, no electric charge and carries a quantum of energy hv.

Answer 17

photon

Question 18

An _________ is when, during the photoelectric effect, when an e- drops down to fill the vacant shell, the energy released causes an outer shell e- to be ejected.

Answer 18

auger electron

Question 19

The interaction cross section for the photoelectric effect is given by _________. It is strongly dependent on Z, and n = _____ for high Z elements, and n = _____ for low Z elements.

Answer 19

sigma = Z^n / (hv)^3
3
4

Question 20

__________ is when a photon ejects an electron from its shell but not all of its energy is absorbed by the electron, causing a new photon with _______ wavelength and _______ energy. The new photon can cause __________. This interaction is also a _________ event.

Answer 20

Compton effect
shorter
less
further ionization
single electron

Question 21

The probability for compton scattering depends on __________ and is proportional to ___________ and linearly proportional to ___________.

Answer 21

number of electrons in the medium
Z/atomic number
cross section sigma

Question 22

________ is when the photon moves towards the nucleus and changes into electron-positron pair. The positron immediately joins with an electron, annihilating the positron and emitting two new photons with equal but half the energy of the original photons.

Answer 22

Pair production

Question 23

The photoelectric effect dominates at ________ energies (_______), pair production dominates at ________ energies (_______), and compton effect dominates at _______ energies (________).

Answer 23

low
0.01-0.07 MeV
high
20-100 MeV
medium
0.1 - 10 MeV

Question 23

The gap between attenuation and absorption for mass absorption is due to ___________.

Answer 23

loss of photon from Compton

Question 24

Photon radiation is ________ ionizing because ____________.

Answer 24

indirectly electrons ionize much more efficiently

Question 25

Neutrons interact with ________ of the atoms, resulting in ________ or _________ or hit an oxygen atom to produce _________.

Answer 25

recoil photons spallation products four alpha particles

Question 26

Ions interact with matter through 3 different processes depending on their energy: 1. ____________, _____ energy 2. ____________, ______ energy 3. ____________, ______ energy These are ______ ionization interactions.

Answer 26

electron capture, low collisions with atomic electrons, medium and high nuclear collisions and nuclear reactions, very high direct

Question 27

The four processes in which electrons interact with matter are _________, __________, ___________ and ___________.

Answer 27

collisions with shell electrons bremsstrahlung cherenkov radiation nuclear reactions

Question 28

_________ is emitted when a charged particle passes through a dielectric medium at a speed greater than the phase velocity of light in that medium. The charged particles polarize the molecules of the medium, which then rapidly turn back to their ground state, emitting radiation in the process.

Answer 28

Cherenkov radiation

Question 29

The speed of the propagation of light in water is ________.

Answer 29

0.75c

Question 30

For cherenkov radiation if the particle travels slowly, then ______________ as particle passes. If the particle is moving very fast , then ________________ as particle passes.

Answer 30

disturbance relaxes elastically back to mechanical equilibrium a disturbance is left behind and the energy contained in this radiates

Question 31

Cherenkov radiation has biomedical applications in ______________, _____________, and ______________.

Answer 31

detection of labelled biomolecules medical imaging of radioisotopes external beam radiotherapy

Question 32

Cherenkov radiation is emitted by ___________ for detection of labelled biomolecules.

Answer 32

phosphorus-32

Question 33

For indirectly ionizing radiation, most of the primarily absorbed energy goes to _________ which _________.

Answer 33

secondary particles cause ionizations and excitations in the matter

Question 34

In photon radiation __________ are secondary particles.

Answer 34

electrons