Chapter 2: Radiation Physics

Question 1

What is matter?

Answer 1

Matter is anything that occupies space and has mass

Question 2

When matter is altered, ______ results

Answer 2

Energy

Question 3

Define mass number (atomic weight)

Answer 3

The number of protons (+) AND neutrons (no electric charge) located in the nucleus

Question 4

Define Atomic Number

Answer 4

The number of protons inside the nucleus

Question 5

An atom contains a max of 7 shells. Each shell has a max number of electrons it can hold. How are these electrons maintained in their orbits?

Answer 5

Electrostatic force, or attraction;

Also known as binding energy, or binding force of an electron

Question 6

What is a molecule and what TWO ways are they formed?

Answer 6

A molecule is two or more atoms joined by chemical bonds.

They are formed (1) by the transfer or electrons or (2) by the sharing of electrons between the outermost shells of atoms

Question 7

Describe a neutral atom

Answer 7

Contains an equal number of protons (+) and electrons (-)

Question 8

What is an ion?

Answer 8

An atom that gains or loses an electron (-) and becomes electrically unbalanced

Question 9

Ionization?

Answer 9

The production of ions, or the process of converting an atom into ions

Question 10

Radiation and Radioactivity is sometimes confused. What is the difference between radiation and radioactivity?

Answer 10

Radiation: is a form of energy carried through space or a substance in the form waves or particles

Radioactivity: a process by which unstable atoms or elements undergo spontaneous disintegration, or decay, in an effort to attain a more balanced nuclear state

Question 11

Define Ionizing radiation and name it’s two classifications

Answer 11

Radiation that is capable of producing ions by removing or adding an electron to an atom.

It can be classified as either particulate or electromagnetic

Question 12

What results when an electron is removed from an atom in the ionization process?

Answer 12

An ion pair results!

The atom becomes the positive ion, and the ejected electron becomes the negative ion.

Question 13

Where is the strongest binding energy found?

Answer 13

Closest to the nucleus (K shell)

Question 14

Define Molecule

Answer 14

Defined as two or more atoms joined by chemical bonds.

Can be formed (1) by the transfer of electrons or (2) by the sharing of electrons between the outermost shells of atoms

Question 15

Define particulate radiation and name the four types:

Answer 15

tiny particles of matter that possess and travel in straight lines and at high speeds:

• electrons:
• -beta particles
• –cathode rays
• alpha particles
• protons
• neutrons

Question 16

Define electromagnetic radiation and give examples

Answer 16

Propagation of wavelike energy (without mass) through space or matter

Examples include: cosmic rays, gamma rays, x-rays, ultraviolet rays, visible light, infrared light, radar waves, microwaves, and radio waves

Question 17

Name some properties of x-rays

Answer 17

Invisible; no mass or weight; no charge; travel @ the speed of light; short wavelengths and high frequencies; cannot be focused to a point; travel in a straight line, but can be deflected or scattered; can penetrate liquids, solids, and gasses; absorbed by matter; can cause ionization; CAUSE biological changes in living cells

Question 18

What is a lead collimator?

Answer 18

restricts the size of the x-ray beam

Question 19

Where are electrons produced?

Answer 19

Electrons are produced in the tungsten filament, when heated. Tungsten filament is found in the cathode (negative)

Question 20

Where do the electrons travel to from the cathode (-)?

Answer 20

Anode (positive) consists of a tungsten target where electrons are converted into x-ray photons

Question 21

What is a circuit?

Answer 21

A path of electrical current

Question 22

Compton scatter?

Answer 22

Accounts for 62% of the scatter that occurs in diagnostic radiography.
Ionization takes place

Question 23

Coherent scatter?

Answer 23

NO loss of energy and NO ionization occurs.

Accounts for 8% of the interactions of the dental x-ray beam with matter.