Dentistry Chapter 2 Heart Generating System Alters Voltage Incoming

Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 1

Radiation Physics

Chapter 2

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Slide 2

Learning Objectives

Lesson 2.1: Atoms, Ionization, and Radiation

1. Define the key terms associated with radiation

physics.

2. Identify the structure of the atom.

3. Describe the process of ionization.

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Slide 3

Introduction

Purpose

To present the fundamental concepts of atomic

and molecular structure

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 4

Atomic and Molecular Structure

Matter

Matter is anything that occupies space and has

mass.

When matter is altered, energy results.

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Slide 5

Atomic Structure

Atom

Atom is a central nucleus and orbiting electrons.

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Slide 6

Nucleus

Nucleus is composed of protons and neutrons.

Protons have positive electrical charges.

Neutrons carry no electrical charge.

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 7

Nucleus (Cont.)

The number of protons and neutrons in the

nucleus of an atom determines its mass

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Slide 8

Electrons

Electrons are tiny, negatively charged

particles.

These have very little mass, approximately 1/1800

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Slide 9

Electrons (Cont.)

Electrons are maintained in their orbits by

electrostatic force between the positive nucleus

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 10

Molecular Structure

Atoms are capable of combining with one

another to form molecules.

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Slide 11

Molecular Structure (Cont.)

Molecules are formed in two ways.

The transfer of electrons

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Slide 12

Ionization

Ionization

Normally, most atoms are neutral.

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 13

Ionization (Cont.)

If the atom gains an electron, it has a

negative charge.

If the atom loses an electron, it has a positive

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Slide 14

Ionization (Cont.)

Ionization is the production of ions, or the

process of converting an atom into ions.

When an electron is removed from an atom in

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Slide 15

Radiation and Radioactivity

Radiation

Radiation is the emission and propagation of

energy through space or a substance in the form

of waves or particles.

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 16

Ionizing Radiation

Radiation is capable of producing ions by

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Slide 17

Particulate Radiation

Particulate radiation is tiny particles of matter

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Slide 18

Particulate Radiation (Cont.)

(1) Electrons

Beta particles are fast-moving electrons emitted

from nucleus of radioactive atoms.

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 19

Particulate Radiation (Cont.)

(3) Protons

Accelerated hydrogen nuclei

Mass of 1 and charge of +1

(4) Neutrons

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Slide 20

Electromagnetic Radiation

This is the propagation of wavelike energy

(without mass) through space or matter.

Oscillating electric and magnetic fields are

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Slide 21

Electromagnetic Radiation (Cont.)

All have common characteristics.

They may be classified as ionizing or non-ionizing.

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 22

Particle Concept

Particle concept characterizes electromagnetic

radiation in terms of discrete bundles of energy

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Slide 23

Wave Concept

Characterizes electromagnetic radiations as

waves

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Slide 24

Learning Objectives

Lesson 2.2: Dental X-Rays

7. List the properties of x-radiation.

8. Identify the component parts of the x-ray

machine.

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 25

X-Radiation

X-radiation is high-energy, ionizing

electromagnetic radiation.

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Slide 26

X-Ray Machine: Component Parts

Control panel

Extension arm

Tubehead

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Slide 27

Control Panel

Contains an on-off switch

Indicator light

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 28

Extension Arm

Suspends the x-ray tubehead

Houses the electrical wires that extend from

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Slide 29

Tubehead

A tightly sealed, heavy metal housing

Contains the x-ray tube that produces dental x-rays

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Slide 30

Tubehead (Cont.)

Tubehead seal

Permits exit of x-rays from tubehead, seals the oil,

filters x-ray beam

X-ray tube

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 31

Tubehead (Cont.)

Aluminum disks

Filter out nonpenetrating, longer wavelength x-rays

Lead collimator

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Slide 32

X-Ray Tube

A glass vacuum tube

Measures several inches long by 1 inch in diameter

Includes:

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Slide 33

Leaded-Glass Housing

A leaded-glass vacuum tube

Prevents x-rays from escaping in all directions

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 34

Cathode (−)

The negative electrode

Consists of a tungsten wire filament in a

cup-shaped holder made of molybdenum

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Slide 35

Anode (+)

The positive electrode

Consists of a wafer-thin tungsten plate embedded

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Slide 36

X-Ray Generating Apparatus

Electricity and electrical currents

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 37

Electricity and Electrical Currents

Electricity

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Slide 38

Direct current (DC)

When electrons flow in one direction through a

conductor

Electricity and Electrical Currents (Cont.)

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Slide 39

Amperage

Amperage is the measurement of the number of

electrons moving through a conductor.

Electricity and Electrical Currents (Cont.)

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 40

Milliamperage adjustment

Can increase or decrease the number of electrons

Electricity and Electrical Currents (Cont.)

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Slide 41

Circuits

Circuit

A path of electrical current

•Filament circuit

Uses 3 to 5 volts

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Slide 42

Transformers

A transformer is a device used to either

increase or decrease the voltage in an

electrical circuit.

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 43

Step-Down Transformer

Used to decrease voltage from the incoming

110– or 220-line voltage to the 3 to 5 volts

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Slide 44

Step-Up Transformer

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Slide 45

Autotransformer

A voltage compensator

Corrects for minor fluctuations in current

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 46

Production of X-Radiation

Production of dental x-rays

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Slide 47

Production of Dental X-Rays

Electricity from the wall outlet supplies the

power to generate x-rays.

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Slide 48

Production of Dental X-Rays (Cont.)

The electrons stay in an electron cloud until

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 49

Production of Dental X-Rays (Cont.)

A small number of x-rays are able to exit the

x-ray tube through the unleaded glass

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Slide 50

Types of X-Rays Produced

X-rays differ in energy and wavelength.

Two mechanisms

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Slide 51

General Radiation

Many electrons that interact with the tungsten

atoms undergo not one but many interactions

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 52

Characteristic Radiation

Characteristic radiation is produced when a

high-speed electron dislodges an inner-shell

electron from a tungsten atom and causes

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Slide 53

Definitions of X-Radiation

Primary radiation

The penetrating x-ray beam that is produced at

the target of the anode

Secondary radiation

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Slide 54

Interactions of X-Radiation

No interaction

Absorption of energy and photoelectric effect

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 55

No Interaction

The x-ray photon passes through the atom

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Slide 56

Absorption of Energy

and Photoelectric Effect

The x-ray photon is completely absorbed

within matter or the tissues of the patient.

Absorption

•The total transfer of energy from photon to the atoms of

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Slide 57

Compton Scatter

The x-ray photon is deflected from its path

during its passage through matter.

In Compton scatter, ionization takes place.

•An x-ray photon collides with a loosely bound, outer-shell

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Dental Radiography: Principles and Techniques, 5th Edition

Chapter 2 Student Handout

Slide 58

Coherent Scatter

Coherent scatter is an x-ray photon that has

its path altered by matter.

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Slide 59

Questions?

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