***Chapter 3 - Interaction Of Radiation With Matter

Question 1

Amount of ionization per mass of air due to X-rays and gamma rays; SI UNIT: C kg-1 (formerly Roentgen (R))

Answer 1

Exposure (X)

Question 2

Amount of energy imparted by radiation per mass; SI UNIT: Gray(Gy); (formerly rad)

1 Gy= J kg-1
1 rad=0.01 J kg-1

Answer 2

Absorbed dose (D)

Question 3

Kinetic energy transferred to charged particles per unit mass; SI UNIT: Gray(Gy)

1 Gy= J kg-1
1 rad=0.01 J kg-1

Answer 3

Kerma (K)

Question 4

Kinetic energy transferred to charged particles per unit mass of air; SI UNIT: Gray(Gy)

1 Gy= J kg-1
1 rad=0.01 J kg-1

Answer 4

Air Kerma (K air)

Question 5

Total radiation energy imparted to matter; SI UNIT: Joule (J)

Answer 5

Imparted energy

Question 6

A measure of ABSORBED DOSE weighted for the biological effectiveness of the type(s) of radiation (relative to LET photons and electrons) to produce stochastic health effects in humans; SI UNIT: Sievert (Sv) , formerly rem

Answer 6

Equivalent dose (H)

Question 7

A measure of EQUIVALENT DOSE, weighted for the biological sensitivity of the exposed tissues and organs (relative to whole body exposure) to stochastic health effects in humans; SI UNIT: Sievert (Sv), formerly rem

Answer 7

Effective Dose (E)

Question 8

Energetic charged particles interact with matter by electrical forces and lose kinetic energy via ______ (3)

Answer 8

1. Excitation
2. Ionization
3. Radiative losses

Question 9

Occur when charged particles lose energy by interacting with orbital electrons in the medium (2)

Answer 9

Excitation and ionization

Question 10

Refer to the coulombic forces exerted in the charged particles when they pass in proximity to the electric field generated by the atom’s electron and protons

Answer 10

Interactions or collisional losses

Question 11

The transfer of some of the incident particles’ energy to electrons in the absorbing material , promoting them to electron orbits farther from the nucleus

Answer 11

Excitation

Question 12

Electron returning to a lower energy level, with the emission of the excitation energy in the form of electromagnetic radiation or Auger electrons

Answer 12

De-excitation

Question 13

Result of an ionization

• consists of the ejected electron and the positively charged atom

Answer 13

Ion pair

Question 14

Sometimes, the ejected electrons possess sufficient energy to produce further ionizations called the ______

Answer 14

Secondary ionization

*these electrons are called DELTA RAYS

Question 15

Average number of primary and secondary ion pairs produce per unit length of the charged particle’s path

Answer 15

Specific ionization

*expressed in ion pairs (IP)/mm

Question 16

As the alpha particle slows, the specific ionization increases to a maximum called the ____

Answer 16

Bragg peak

Question 17

Defined as the distance the particle travels

Answer 17

Path length

Question 18

Defined as the depth of penetration of the particle in matter

Answer 18

Range

Question 19

A measure of the average amount of energy deposited locally (near the incident particle track) in the absorber per unit path length

• expressed in units of keV or eV per um
• describes the local energy deposition density , which can have a substantial impact on the biological consequences of radiation exposure

Answer 19

Linear energy transfer (LET)

Question 20

Refers to an interaction that deflects a particle or photo from its original trajectory

Answer 20

Scattering

Question 21

A scattering event in which the total kinetic energy of the colliding particles is unchanged is called _____

Answer 21

Elastic

Question 22

Type of interaction when scattering occurs with a loss of kinetic energy

Answer 22

Inelastic

Question 23

Radiation emission accompanying electron deceleration

Answer 23

BREMSSTRAHLUNG

- “braking radiation”

Question 24

The fate of positrons (B+) that ultimately become bound to atoms

Answer 24

Positron annihilation