Chapter 38 Lesson 38.1 Chapter 38 Lesson 38.2 Chapter 38 Lesson 38.3

Chapter 38 Lesson 38.1 Chapter 38 Lesson 38.2 Chapter 38 Lesson 38.3 www.phwiki.com

Chapter 38 Lesson 38.1 Chapter 38 Lesson 38.2 Chapter 38 Lesson 38.3

Reed, Gary, Forum Editor has reference to this Academic Journal, PHwiki organized this Journal Foundations of Radiography, Radiographic Equipment, in addition to Radiologic Safety Chapter 38 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Chapter 38 Lesson 38.1 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Learning Objectives Pronounce, define, in addition to spell the Key Terms. Describe the uses of dental radiographs. Describe the discovery of x-radiation. Name the highlights in the history of dental radiography. Explain what happens during ionization. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

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Introduction The dental assistant must have a thorough knowledge in addition to underst in addition to ing of the importance in addition to uses of dental radiographs. The dental assistant must underst in addition to the fundamental concepts of atomic in addition to molecular structure in addition to have a working knowledge of ionizing radiation in addition to the properties of x-rays. (Cont’d) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Introduction (Cont’d) Radiation used to produce dental radiographs has the capacity to cause damage to all types of living tissues. Any exposure to radiation, no matter how small, has the potential to cause biologic changes to the operator in addition to the patient. The dental assistant must have a thorough underst in addition to ing of the characteristics of radiation to minimize radiation exposure to both the dental patient in addition to the operator. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Discovery of Radiation Wilhelm Conrad Roentgen (pronounced rent-ken), a Bavarian physicist, discovered the x-ray on November 8, 1895. For many years x-rays were referred to as roentgen rays, radiology was referred to as roentgenology, in addition to radiographs were known as roentgenographs. During his lifetime, Roentgen was awarded many honors in addition to distinctions, including the first Nobel Prize ever awarded in physics, in 1901. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fig. 38-1 A, Wilhelm Conrad Roentgen (1845–1923), discoverer of x-rays. (From Frommer HH, Stabulas-Savage J: Radiology as long as the dental professional, ed 8, St Louis, 2005, Mosby.) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Fig. 38-1 B, Crookes tube, which Roentgen worked with at the time of the discovery of x-rays in 1895. (From Frommer HH, Stabulas-Savage J: Radiology as long as the dental professional, ed 8, St Louis, 2005, Mosby.) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Pioneers in Dental Radiography Otto Walkoff made the first dental radiograph. Dr. C. Edmund Kells, a New Orleans dentist, is credited with the first practical use of radiographs in dentistry, in 1896. Dental radiography has progressed from these early discoveries to the science it is today. New technology continues to improve our diagnostic abilities. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Radiation Physics All things in this world are composed of energy in addition to matter. Energy is defined as the capacity to do work. Matter is anything that occupies space in addition to has as long as m or shape. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Energy Although energy can neither be created nor destroyed, it can change as long as m. Atoms contain energy. The energy that holds the nucleus together is called nuclear-binding energy. The energy holding electrons, negatively charged particles, in their shells is known as electron-binding energy. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Matter Matter has many as long as ms, including solids, liquids, in addition to gases. Matter is composed of atoms grouped together in specific arrangements called molecules. A molecule is the smallest particle of substance that retains the property of the original substance. The fundamental unit of matter as long as discussion in this chapter is the atom. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Atomic Structure The atom consists of two parts: Central nucleus Orbiting electrons An atom is identified by the composition of its nucleus in addition to the arrangement of its orbiting electrons; at present, 105 different atoms are known to exist. (Cont’d) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Atomic Structure (Cont’d) The arrangement within the atom is similar to that of the solar system. The atom has a nucleus as its center or sun, in addition to the electrons revolve (orbit) around it like planets. The electrons remain stable in their orbit unless disturbed or moved. Orbiting electrons can be disturbed by x-rays. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Fig. 38-3 Diagrammatic representation of an oxygen atom. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Nucleus The nucleus, or dense core, of the atom is composed of particles known as protons in addition to neutrons. Protons carry positive electrical charges; neutrons carry no electrical charge. Dental x-rays do not affect the tightly bound nucleus of the atom in addition to are only changed in direction or scattered. Dental x-rays cannot make atoms radioactive; there as long as e patients do not give off x-rays after the x-ray machine stops producing x-rays. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Electrons Electrons are tiny negatively charged particles with very little mass. Electrons orbit around the nucleus of an atom. The orbit path of an electron is called an electron shell. Each shell can contain only a specific number of electrons. The electrons are maintained in orbit by electron-binding energy, a as long as ce similar to the as long as ce of gravity on earth. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Ionization The electrons remain stable in their orbits around the nucleus until x-ray photons collide with them. (A photon is a minute bundle of pure energy that has no weight or mass.) X-rays have enough energy to push an electron out of its orbit, producing an ion (an atoms that gains or lose an electron in addition to becomes electrically unbalanced) in a process called ionization. (Cont’d) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Ionization (Cont’d) Ionization is the process by which electrons are removed from the orbital shells of electrically stable atoms through collisions with x-ray photons. When an electron is removed from the atom, an ion pair results. The harmful ionizing effect of x-rays in human beings can result in a disruption of cellular metabolism in addition to can cause permanent damage to living cells in addition to tissues. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Fig. 38-4 A molecule of water (H2O) consists of two atoms of hydrogen connected to one atom of oxygen. (From Haring JI, Jansen L: Dental radiography: principles in addition to techniques, ed 2, Philadelphia, 2000, Saunders.) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Chapter 38 Lesson 38.2 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Learning Objectives Describe the properties of x-radiation. Label the parts of the dental x-ray tubehead in addition to tube. Explain how radiographs are produced. Identify the range of kilovoltage in addition to milliamperage required as long as dental radiography. (Cont’d) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Learning Objectives (Cont’d) Describe the effect of the kilovoltage on the quality of the x-ray beam. Describe how the milliamperage affects the quality of the x-ray beam. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Properties of X-Rays The dental assistant must be familiar with the unique characteristics of x-rays. X-rays are a as long as m of energy that can penetrate matter. Like visible light, radar, radio, in addition to television waves, they belong to a group called electromagnetic radiation. Electromagnetic radiation is made up of photons that travel through space at the speed of light in a straight line with a wavelike motion. (Cont’d) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

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Fig. 38-6 Electromagnetic spectrum, showing the various wavelengths of radiation typically used. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Properties of X-Rays (Cont’d) The shorter the wavelength, the greater its energy. The high energy of short wavelengths means that they can penetrate matter more easily than longer wavelengths can. X-rays have unique properties that make them especially useful in dentistry. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. A B Fig. 38-7 A, Wavelength is the distance between the crest (peak) of one wave in addition to the crest of the next. B, The shorter the wavelength, the greater the energy in addition to penetration, the longer the wavelength, the less energy in addition to less penetration. (From Haring J, Jansen L: Dental radiography: principles in addition to techniques, ed 2, Philadelphia, 2000, Saunders.) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Components of the Dental X-Ray Machine Dental x-ray machines may vary somewhat in size in addition to appearance, but all machines will have three primary components: The tubehead An extension arm The control panel Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. Fig. 38-8 Dental x-ray machine in addition to arm. A, Tubehead. B, Position-indicator device (PID). C, Extension arm. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. The Tubehead The x-ray tubehead is tightly sealed; heavy metal housing contains the x-ray tube that produces dental x-rays. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Patient Questions (Cont’d) Here are some examples of comments you can make to patients during in as long as mal discussions: “The doctor orders x-rays on the basis of your individual needs.” “Our office takes every step possible to protect you from unnecessary radiation.” “We use a lead apron in addition to thyroid collar to protect your body from stray radiation.” “We use a high-speed film that requires only minimal amounts of radiation.” “Do you have any questions be as long as e we begin” Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

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