B. Radiation physics

Question 1

___ is the number of waves that pass a given point in one second.

Answer 1

Frequency

Question 2

wavelength

Answer 2

the measured distance between two specific points of the wave

ex - peak to peak
- valley - valley

Question 3

velocity

Answer 3

how fast the wave is traveling

• x-rays travel at the speed of light (c) in a vacuum

Question 4

Si unit for velocity is _____

Answer 4

3 x 10^8 m/sec

Question 5

Amplitude

Answer 5

half of the distance from one crest to one valley

• photons have both wave and particles distances
• photons have no mass or charge and low LET

Question 6

wavelength is measured in

Answer 6

meters

Question 7

wavelength and frequency are inverse relationship

Answer 7

wavelength will be short and frequency will be long and vice versa

Question 8

the beams intensity will ______ more as the thickness of attenuating material ______

Answer 8

decreases , increases

Question 9

what is the formula for attenuation of matter

Answer 9

I(X) = I e^-ux

I = initial intensity
u = linear attenuation coefficient
x = thickness of absorption material

Question 10

As the radiation beam travels through matter, it will diverge and decrease in intensity because of the

Answer 10

inverse square effect

Question 11

As the radiation beam travels through matter, it will diverge and decrease in intensity because of the

Answer 11

direction than it travels through matter

Question 12

____ is inversely proportional to square of distance from source

Answer 12

beam intensity

Question 13

Different types of radiation have different beam qualities and can produce different ____

Answer 13

amounts of response

Question 14

Quality factor (QF) are assigned to describe the type of

Answer 14

Radiation

Question 15

x-rays, gamma rays , beta particles , electrons

Answer 15

Quality factor = 1

Question 16

protons

Answer 16

quality factor = 2

Question 17

neutrons

Answer 17

Quality factor = 3-10

Question 18

heavy particles

Answer 18

quality factor = 20

Question 19

____________ is when the photon interacts occurs with an outer shell atomic electron and the photon becomes REDIRECTED OR SCATTERED from its original path without any CHANGE IN ENERGY

Answer 19

Coherent (or elastic) scattering

Question 20

coherent occurs with ______ energies and _____ z# (atomic number

usually occurs with energies less than ____

Answer 20

low energies and materials with high z#

usually occurs with energies less than 10 Kev

Question 21

Photoelectric effect occurs more with low energy photons interacting with material with a

Answer 21

high z number

Question 22

________ is when the photon interacts with the inner shell electron and is then absorbed by this electron, and its energy is transfered

• results in a photoelectron being ejected from the atom

Answer 22

photoelectric effect

Question 23

Photoelectric effect occurs in diganostic energy ranges more than

Answer 23

therapy energy ranges

Question 24

helps to create contrast on an x-ray image (black and white due to absorption)

Question 25

the photon interacts with an OUTER SHELL ATOMIC ELECTRON and GIVES UP PARTIAL ENERGY BEFORE CHANGES DIRECTION

Answer 25

Compton scaterring

Question 26

compton scattering interacts in ______ ________ in radiation therapy

• occurs in energy from _______

Answer 26

• soft tissues
• 25 kv - 10 MV

Question 27

_______ incoming photon disappear and then reappears as an electron positron pair

Answer 27

pair production

Question 28

IN pair production the electron pair become two

Answer 28

.511 MeV photons

Question 29

threshold energy needed for pair production

Answer 29

> 1.022 MeV

Question 30

_______ photon goes in to nucleus and neutron comes out

Answer 30

photon nuclear reactions (photon disintegration):

Question 31

occurs in high Z# material such as collimating jaws

occurs in ______

Answer 31

7-15 MeV

Question 32

neutron radiation occurs in the treatment room with energies greater than

Answer 32

10 MV

Question 33

Common electron energies in linacs are

Answer 33

5-20 MeV

Question 34

_______ is describes that some kinetic energy is lsot and reappears in another form of energy like excitation, ionization, bremsstrahlung, etc.

Answer 34

inelastic collision

Question 35

______ the total kinetic energy before the collision is the same as the total kinetic energy after the collision

Answer 35

elastic collision

Question 36

the differences in density will affect how the beam ______ though the matter and how it _____ as well (dose distribution)

Answer 36

pentrates

• scatters

Question 37

Electron travel in a _______ path

Answer 37

“zigzag” or “tortured”

Question 38

Electrons are easily scattered by high Z number material because

Answer 38

of their low mass

Question 39

Electron interactions are

Answer 39

bremsstrahlung and characteristic

Question 40

protons are 2,000 times heavier than

Answer 40

electrons

Question 41

The body is made up of tissues with different

Answer 41

densities

Question 42

The difference in the density of tissue will effect how the beam penetrates through matter and how i

Answer 42

scatters as well

Question 43

The lungs density is about

Answer 43

0.25-0.33 g/cm^3 ( beam will penetrate easier)

Question 44

Bone density is about

Answer 44

1.8 g/cm^3 ( beam will attenuate more)

Question 45

Answer 45