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Chapter 38
Notes
| Question | Answer |
|---|---|
| Radiography | referred to as dental imaging |
| dental diseases and conditions with no clinical signs or symptoms and are typically discovered only with the use of | dental imaging. |
| The term image receptor | is used when referring to either a digital imaging sensor or to film because the image is recorded on one or the other, depending on the system being used. |
| USES OF DENTAL IMAGES | Detects dental caries on any surface of tooth structure, especially interproximal surfaces and beneath existing restorations that cannot be visually seen. |
| USES OF DENTAL IMAGES | Identifies periodontal disease involving bone loss in the early stages. |
| USES OF DENTAL IMAGES | Locates pathological abnormalities in surrounding hard and soft tissues. |
| USES OF DENTAL IMAGES | Evaluates growth and development of teeth. |
| USES OF DENTAL IMAGES | Provides clinical status during a dental procedure (such as root canal therapy). |
| USES OF DENTAL IMAGES | Is a legal document of a patient’s condition at a specific time. |
| Radiation | which is a useful tool to produce all types of dental images, also has the ability to cause damage to all types of living tissues. |
| Any exposure to | radiation, no matter how small, has the potential to cause harmful biologic changes to the operator and the patient if the principles of safety when working with radiation is not thoroughly understood. |
| Wilhelm Conrad Roentgen | discovered the x-ray in 1895 |
| Roentgen had experimented with the production of | cathode rays (streams of electrons). |
| What was used when roentgen discovered x-rays | He used a Crookes tube (vacuum tube), an electrical current, and special screen covered with a material that glowed (fluoresced) when exposed to x-rays |
| The symbol x | is used in mathematics to represent the unknown |
| Many of his colleagues referred to x-rays as | roentgen rays |
| radiology | roentgenology |
| radiographs | roentgenographs. |
| In 1896, German dentist Otto Walkhoff made the first | dental radiograph |
| Otto Walkhoff | placed a glass photographic plate wrapped in black paper and rubber in his mouth and submitted himself to 25 minutes of x-ray exposure. |
| C. Edmund Kells is credited with the first | practical use of radiographs in dentistry in 1896. |
| William D. Coolidge, an electrical engineer, developed the first | hot-cathode x-ray tube, a high-vacuum tube that contained a tungsten filament This was the prototype for modern x-ray tubes. |
| In 1923, a miniature version of the x-ray tube... | was placed in the head of an x-ray machine and immersed in oil |
| dental x-ray machine changed very little until... | a variable kilovoltage machine was introduced in 1957. |
| In 1966, | a recessed long-beam tubehead was introduced. |
| Energy | is defined as the ability to do work. Although energy cannot be created or destroyed, it can change form. |
| Atoms | are the basic form of matter, and they contain energy. |
| Matter | is anything that occupies space and has form or shape. |
| 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 atom consists of two parts: | a central nucleus and orbiting electrons |
| The nucleus, | is composed of particles known as protons and neutrons. |
| Protons carry | positive electrical charges |
| neutrons carry | no charge. |
| Dental x-rays do not affect the tightly bound nucleus of atoms,... | however, they can be scattered or change directions and have the ability to remove electrons, which orbit around the nucleus. |
| Dental x-rays cannot | make atoms radioactive; |
| The orbital path of an electron around the nucleus is called an | electron shell. |
| Electrons are maintained in orbit by electron binding energy, | a force similar to gravity |
| Bremsstrahlung radiation | is the primary kind of radiation produced in the dental x-ray tubehead |
| Bremsstrahlung radiation is produced when | an electron from the cathode directly hits the nucleus of a target atom, causing it to stop suddenly, |
| Bremsstrahlung radiation is produced when | passes so close to the nucleus of a target atom that the negatively charged (–) electron is pulled off course by the positively charged (+) nucleus, slowing it down considerably |
| Energy lost by deceleration | of the electron is emitted in the form of either heat or radiation. |
| The incoming electron (from the cathode).... | slows as it is drawn to the nucleus of the atom. |
| Some of the energy lost.... | in the deceleration is emitted as an x-ray photon with energy equal to that lost by the electron. |
| Electrons remain stable in their orbit around the nucleus until... | radiograph photons collide with them. |
| A photon is | a minute (tiny) bundle of pure energy that has no weight or mass. |
| Ions are | atoms that gain or lose an electron and become electrically unbalanced. |
| X-rays have enough energy to produce ions because of a process called | ionization. |
| electrons are removed from the | orbital shells of electrically stable atoms through collisions with x-ray photons |
| Ionization occurs when | electron is removed from the orbital shell of the electronically stable atom |
| CHARACTERISTICS OF X-RAYS | Invisible and undetectable by the senses • No mass or weight • No charge • Travel at speed of light |
| CHARACTERISTICS OF X-RAYS | Travel in short-wavelength, high-frequency waves • Travel in straight line and can be deflected or scattered • Absorbed by matter • Cause ionization |
| CHARACTERISTICS OF X-RAYS | Can cause certain substances to fluoresce • Can produce image on photographic film • Cause changes in living cells |
| X-rays are a form of | energy that can penetrate matter. |
| X-rays belong to a group classified as | electromagnetic radiation |
| Visible light, radar, radio, and television waves are also classified as | electromagnetic radiation |
| Electromagnetic radiation is believed to be made up of | small particles called photons |
| photons travel through space with a .... | wavelike motion |
| The shorter the wavelength of the x-ray, | the greater is its energy. |
| short wavelengths can penetrate.... | matter more easily than longer wavelengths |
| making shorter wavelengths especially useful | in dentistry |
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alejac0360