Chapter 2 - RADIATION - TYPES, SOURCES, & DOSES

Question 1

What terms (w/ units) are used to represent the electromagnetic spectrum?

Answer 1

Frequency ( Hz)
Wavelength (meters)
Energy (eV)

Velocity - speed of light (300 million meters per second in a vacuum or 186,000 miles per second)

Question 2

What is ionizing radiation ?

& examples

Answer 2

can eject orbital electrons
Can create images
Can produce biologic damage

-x-rays
-gamma rays
-UV radiation w energy greater than 10eV

Question 3

What is nonionizing radiation?

& examples

Answer 3

lack kinetic energy to eject an electron from orbit.

-UV less than 10eV
-visible light
-infrared rays
-microwaves
-radio waves

Question 4

What is particulate radiation?

Answer 4

subatomic particles ejected from the nucleus of an atom at veery high speeds

Question 5

Alpha particles

Answer 5

emitted from the nuclei of very heavy elements (uranium, plutonium) during the process of radioactive decay
-contain 2 protons and 2 neutrons
-positive charge (+2) and large mass with the potential to transfer kinetic energy
-lose energy quickly
** highest biologic effect - internal structures

Question 6

Beta particles

Answer 6

identical to high-speed electrons except origin.
-emitted from the nucleus of radioactive atoms
-nucleus relieves instability by neutron transforming into proton and energetic electron
-small mass (8000x lighter than alpha)
-negative charge (-1)
(radiation therapy oncology)

Question 7

Protons

Answer 7

positively charged components of an atom
- # of protons in nucleus = atomic #/ Z#

Question 8

Neutrons

Answer 8

electrically neutral component of an atom

Question 9

Isotope

Answer 9

when two atoms have the same number of protons, but differ in the number of neutrons

-radioisotopes used in NM

Question 10

Absorbed dose

Answer 10

kinetic energy per unit mass that has been absorbed in a material.
-patient dose-
mGy / mrad

Question 11

Equivalent dose

Answer 11

takes into account type of ionizing radiation that was absorbed as well as the variation in biologic harm produced by different types of radiation (protons, neutrons, electrons)
mSV/ mrem
- tech dose-
EqD=D x Wr

Question 12

Effective Dose

Answer 12

takes into account the type of radiation and the part of the body irradiated
- best estimate of overall harm

mSv/mrem

EfD=D x Wr x Wt

Question 13

Levels of biologic damage potential

Answer 13

1. atomic level- electrons can be knocked out of orbit, damage can be repaired by attraction of a free electron
2. Molecular level- abnormal or complete loss of cell function/ mutation
   – leukemia, cataracts –
3. organic level- tissue damage can be repaired by cell repopulation

Question 14

Sources of radiation

Answer 14

Natural
-terrestrial
-cosmic
-internal
Human-made
-consumer products
-air travel
-nuclear fuel for generation of power
-atomic fallout from nuclear weapons
-nuclear power plant accidents
** medical radiation

Question 15

average yearly total dose –
-Natural
-Human-made

Answer 15

total 5.5 mSv
natural - 3.1mSv
(terrestrial 2.3mSv, cosmic .3mSv, internal .5mSv)
human-made- 2.4mSv
medical- 2.3
CT: 1.5 of the total 2.3