UNIT 1: Radiation Types, Sources, and Doses

Question 1

What are some characteristics of the frequencies on the electromagnetic spectrum?

Answer 1

Higher frequencies are associated with shorter wavelengths and higher energies; therefore, as the wavelength ranges from largest to smallest, frequencies and energy cover the corresponding smallest to largest ranges.

Question 2

What types of radiation are classified as ionizing?

Answer 2

• X-rays
• Gamma rays
• Ultraviolet radiation with an energy greater than 10 eV

Question 3

What types of radiation are classified as non-ionizing?

Answer 3

• Ultraviolet radiation with energy less than 10 eV
• Visible light
• Infrared rays
• Microwaves
• Radio waves

Question 4

What is the difference between ionizing and non-ionizing radiation?

Answer 4

Ionizing radiation can produce damage in biological tissue and are capable transferring sufficient energy to remove orbital electrons from the atoms to which they were attached, non-ionizing radiation does not remove orbital electrons or damage biological tissue

Question 5

Define Particulate Radiation

Answer 5

-Subatomic particles that are ejected from the nucleus of atoms at very high speeds
-Another category of ionizing radiation, includes the following:
• Alpha particles
• Beta particles
• Neutrons
• Protons

Question 6

Describe alpha particles

Answer 6

Alpha particles, also known as alpha rays, are emitted from nuclei of very heavy elements, such as uranium and plutonium, during their radioactive decay

Usually harmless as an external source of radiation, except If emitted from a radioisotope that was deposited in the body—for example, in the lungs—alpha particles will be absorbed in the relatively radiosensitive epithelial tissue and be extremely damaging to that tissue.

Question 7

Describe beta particles

Answer 7

also known as beta rays, are identical to high-speed electrons except for their origin. Electrons originate in atomic shells (Appendix F) outside of the nucleus, whereas beta particles, like alpha particles, are emitted from within the nuclei of radioactive atoms

Can penetrate deeper than Alpha particles but with less damage to surrounding tissue

Question 8

What is a proton?

Answer 8

Protons are positively charged components of an atom

Question 9

What is a neutron?

Answer 9

the electrically neutral components of an atom and have approximately the same mass as a proton

Question 10

Define absorbed dose and what is its unit of measure.

Answer 10

absorbed dose (often just called “dose”), is defined to be the amount of energy per unit mass that has been absorbed in a material due to its interaction with ionizing radiation. It is usually measured in units called gray (Gy) or fractions of a gray called centigray (cGy).

1 cGy =.01 Gy.

Question 11

Define equivalent dose and what is its unit of measure

Answer 11

Equivalent dose (EqD) takes into account the type of ionizing radiation that was absorbed. The EqD provides an overall dose value that includes the different degrees of tissue interaction that could be caused by the different types of ionizing radiation.

The most common unit of measure of EqD is the millisievert (mSv). 1 mSv = 1/1000th of a Sievert.

Question 12

Define effective dose and identify its unit of measure.

Answer 12

The effective dose is intended to be the best estimate of overall harm that might be produced by a given absorbed dose of radiation in human tissue. It takes into account both the type of radiation and the part of the body irradiated.

The standard unit of effective dose is the same as that of the equivalent dose, the mSv

Question 13

Describe how potential damage can result from ionizing radiation.

Answer 13

While penetrating body tissue, ionizing radiation primarily causes biologic damage by ejecting electrons from the atoms, composing the tissue. Destructive radiation interaction at the atomic level results in molecular change, and this in turn, can cause cellular damage, leading to abnormal cell function or even complete loss of cell function.

Question 14

What are the sources of radiation?

Answer 14

• Natural:
• Terrestrial radiation from radioactive materials in the crust of the Earth
• Cosmic radiation from the sun (solar) and beyond the solar system (galactic)
• Internal radiation from radioactive atoms, also known as radionuclides, which make up a small percentage of the body’s tissue
• Human-made (artificial)

• Manmade (artificial):
•Consumer products containing radioactive material
• Nuclear fuel for the generation of power
• Atmospheric fallout from nuclear weapons testing
• Nuclear power plant accidents
• Nuclear power plant accidents as a consequence of natural disasters
• Medical radiation

Question 15

What is the average annual background radiation exposure people receive?

Answer 15

3.1 mSv

Question 16

What is the average annual exposure people receive from medical imaging?

Answer 16

2.3 mSv