CH3: EM Radiation and Particulate Radiation

Question 1

How is all EM Radiation is similar?

Answer 1

no mass
carries energy in waves of electric and magnetic disturbances through space
travels at speed of light

Question 2

EM spectrum varies in…

Answer 2

energy, wavelength, frequency

Question 3

all energy on the EM spectrum have the same…

Answer 3

velocity or speed

Question 4

What is the speed of light?

Answer 4

3 x 10^8 m/s

Question 5

What occurs to cause EM radiation to be emitted?

Answer 5

radioactive decay - atom with excess energy in it’s nucleus emits particles and energy to regain stability

Question 6

Define a half-life

Answer 6

the time it takes for half the atoms of an element to decay

Question 7

How long does radioactive decay take?

Answer 7

depends, may happen in seconds or billions of years

Question 8

Describe particulate radiation

Answer 8

able to ionize atoms (alpha and beta)

Question 9

Equation to calculate EM energy

Answer 9

E = hf
E – energy measured in eV
h – 4.135 x 10^-15 (Plank’s constant)
f = frequency of photon, measured in Hertz

Question 10

Plank’s Constant, what is it and how is it used

Answer 10

used to calculate photon energies based on frequency
4.135 x 10^(-15)

Question 11

EM radiation may exhibit properties of waves of particles. This is referred to as…

Question 12

List three (3) characteristics exhibited by X rays and gamma rays that are also properties of a particle?

Answer 12

can burn the skin
intensity varies according to inverse square law
able to ionize matter

Question 13

There are five types of non-ionizing EM radiation. List them from low to high. Briefly describe each

Answer 13

radiowaves - radio stations and MRI
Microwaves - cell phones, heating food
Infrared light - signal between remote and TV
Visible light - colors visible to the human eye
Ultraviolet light - higher energies, tanning beds

Question 14

What are the two radiation types on the EM spectrum that are ionizing? How are they used in healthcare?

Answer 14

X-rays - medical imaging
Gamma Rays - nuclear medicine

Question 15

Write the formula for calculating wavelength or frequency.

Answer 15

Velocity = frequency x wavelength

Question 16

A high frequency sine wave would have _____ (long, short) wavelength

Answer 16

short

Question 17

A sine wave with long wavelength would have ___ (high, low) energy

Answer 17

low

Question 18

From one crest a wave to the next crest of a wave is called….

Answer 18

wavelength

Question 19

The height of a wave is called the _____

Answer 19

amplitude

Question 20

How would you describe a photon?

Answer 20

massless package of energy
no mass or charge
speed of light

Question 21

define wave frequency

Answer 21

number of wave cycles per second

Question 22

What is responsible for determining the differences in energy of EM radiation?

Answer 22

wavelength and frequency

Question 23

If an xray beam is polyenergetic, what does that mean?

Answer 23

has various energy levels

Question 24

a majority of photons in the xray beam are created through what process

Answer 24

Bremsstrahlung radiation

Question 25

What is the average energy of the xray beam called?

Answer 25

beam quality

Question 26

What term describes a beam that diverges equally in all directions?

Answer 26

isotropic

Question 27

What are three reasons to know about EM radiation in xray?

Answer 27

1) be able to answer patient questions and assure them of safety
2) to be knowledgeable of the equipment and radiation you use every day
3) dispel misconceptions or myths about x-rays

Question 28

Who is James Maxwell?

Question 29

define velocity in EM radiation

Answer 29

speed of light

Question 30

What uses more energy - higher frequency (short wavelength) or lower frequency (long wavelength)

Answer 30

Higher frequency/short wavelength

Question 31

_____ (high/low) frequency is associated with higher KVP

Answer 31

high

Question 32

A ____ (high/low) frequency wave has more penetrating power in xray.

Answer 32

high

Question 33

What is the overall concept of the inverse square law?

Answer 33

as you move closer to the source, the intensity will increase and vice versa

Question 34

Inverse Square Law Formula

Answer 34

(Intensity 1 / Intensity 2) = (Distance 2^2 / Distance 1^2)

intensity diminishes by a factor of the square of the distance as you move away from the source

Question 35

Differentiate between gamma and xrays

Answer 35

Gamma - originates in the nuclei of atoms when giving off excess energy
X-ray - originates through interaction between atoms and electrons (Brems, Characteristic, Compton, photoelectric)

Question 36

Describe Alpha particles

Answer 36

two protons bound to two neutrons with a net positive charge
LARGE - cannot penetrate most things, cannot travel far
Quickly pick up electrons b/c of positive charge

Question 37

Describe beta particles

Answer 37

an electron emitted from an unstable nucleus
smaller, lighter
can penetrate light materials
longer range and can ionize atoms in its path
positive or negative