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86 Cards in this Set
- Front
- Back
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Introduction |
* The term image receptor is used in this text 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 Dental imaging enables the dentist to see conditions that are not visible in the oral cavity and to find conditions uses |
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Uses of dental images |
Detect caries in early stages, identify bone loss in the early stages, locate abnormalities in surrounding hard/soft tissues,evaluate growth/development, provide info during procedures, document patients condition at a certain time |
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Dental imagines |
To understand how dental images are produced the RDA must first understand the fundamental concepts of atomic structure and have a working knowledge of ionizing radiation and the components of X-ray equipment. Radiation which is used to produce all type of dental images has the ability to cause all types of damage to all types of living tissues. Any exposure to radiation no matter how small has the potential to cause harmful biological changes in the operator and patient. |
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Discovery of X-Radiation |
Wilhelm Conrad Roentgen discovered the X-ray in 1895. The monumental discovery revolutionized diagnostic capabilities and changed the practice of medicine and dentistry forever. He experimented with the production of cathode rays(streams of electrons). He used a crookes rube (vacuum tube) an electrical current and special screens covered with a material that glowed fluorescent when exposed to xrays. His wife’s hand was the first ever X-ray. Xrays are named after him. |
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Heights in the history of dental radiology |
Discovery of X-rays - Roentgen First dental radiograph - Walkhoff First skull X-ray - Morton First live patient - Kelland First paper on danger of xrays - Rollins Into of bisecting technique- Price First dental text - raper First prewrapped films - Eastman First X-ray tube - Coolidge First machine made film packs - Eastman Intro of bitewing - Raper Cone paralleling - Fitzgerald First variable kilo voltage dental X-rays machine - general lettuce Oral/Max radiology speciality - ADA F speed - Eastman |
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Radiation physics |
All thing in the worlds are composed of energy and matter. Energy is defined as the ability to do works although encryption 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 has many forms including solids, liquids, and gases. Matter is composed of atoms grouped together in specific arrangement called molecules. A molecule is the smallest particle substance that retains the property of the original substance. The fundamental unit of matter for discussion in this chapter is Atom. |
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Atomic structure |
Consists of two parts 1. Central nucleus 2. Orbiting electrons An atom is identified by composition of its nucleus and arrangement of its orbiting electrons. The arrangement within a atom is to that of a solar system. The atom has a nucleus (sun) as its center and the electrons (plants) revolve (orbit) around the nucleus. Electrons remains stable in their orbit unless disturbed or moved. X-rays can disturb orbiting electrons. |
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Atomic photo |
Back (Definition) |
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Nucleus |
Composed of particles called protons and neutrons. Protons carry possible charge and neutrons carry a no charge. X-rays don’t affect tightly bond nucleus of the atom and are changed only in direction or scattered. X-rays cannot makes atoms radioactive that is patients do not give of X-rays after X-ray machine stops |
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Electrons |
Tiny negatively charged particles that have very little mass. The orbital path of an electron around the nucleus is called an electron shell. Each shell can contain a certain number of electrons. Electrons are maintained in orbit by electron binding energy. A force similar to gravity |
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Bremsstrahlung radiation |
Produced with an electron passes near the nucleus of an atom. The negative charge electron is deflected by a positive charge nucleus . Energy lost by declaration of the electron is emitted in the form a photon radiation called Bremsstrahlung. Braking radiation is the primary kind of radiation produced in the dental X-ray head. |
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Ionization |
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 a electron and become electrically unbalanced. X-rays have enough energy to produce ions because of a process called ionization. In this process electrons are removed from the obit shells of electrically stable atoms though collisions with X-ray photons. * ionization occurs when an electron is removed from the orbital shell of a stable atom. |
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Properties of X-rays |
X-rays are a form of energy that can penetrate matter. X-ray belong to a group classified as electromagnetic radiation. Visible light, radar, radiology and TV waves are also. It’s made up of photons that travel through space at the speed of light in a straight line with a wavelike motion. The shorter the wavelength of the X-ray the greater it’s energy. Because of their high energy short wavelengths can penetrate matter more easily than longer wavelengths. Short is used in dentistry |
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Characteristics of X-rays |
Invisible and undetectable by senses, no mass or weight, no charge, travel as the speed of light, travel in short wave lengths and high frequency, travel in a straight line but can be deflected or scattered, absorbed by matter, cause ionization, can cause certain substances to fluorescence, can produce image on film, causes changes in living cells. |
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Dental X-ray machine |
Vary in size + appearance slightly. All machines of 3 primary components - tube head, extension arm, control panel. |
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Tube head |
Tightly sealed, heavy metal housing that contains the radiograph tube. Components are - - the housing is a metal body that contains X-ray Tube - insulating oil fills the housing and surrounds the X-ray tube. Oil prevents overheating by absorbing the heart created by the production of X-rays - the tube head seal made of leaded glass or aluminum keeps the oil in the tube head and acts as a filter for the X-ray beam -X-ray tube is where X-rays are produced - transformer alters the voltage of incoming electrical current. The lead collimator is a metal disc with a snaking opening in the centre. It is located inside the position indicator device (PID) in the path of the X-ray beams the small open forms the size and shape of the X-ray beam as it leaves the tube head. Collimator limits the size of the X-ray beam to a circular 2inch opening at the PID. When size and shape of the beam are changed to rectangle only slightly larger than the film the amount of tissue expose to radiation can be reduced by more than half. Aluminum filer is 0.5 thick sheet located inside the PID (open end) |
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X-ray tube |
Heart of the X-ray generating system. Made of glass and 6 by 1 inches. Air has been removed from the tube to create a vacuum. The environment allows electrons to flow with minimal resistance between the electrodes (cathode and anode) Cathode is a negative electrode and anode is positive. Cathode - supply the electrons necessary to generate X-rays Anode - acts as a target for the electrons. It is composed of a tungsten target (a small block of tungsten) serves as SoCal spot and coverts electrons into X-ray photons. Oil absorbs 99% of the X-ray generated by this process and this energy is giving off as heat. The remaining 1% exits the tube head though the port(opening) as a divergent beat toward the patient |
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Position indicator device(PID) |
The lead lined PID is used to rain the X-ray beam at the film in the patients mouth. Open end is placed close to patients face during film exposure. Circle or rectangle |
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Position indicator device(PID) |
The lead lined PID is used to rain the X-ray beam at the film in the patients mouth. Open end is placed close to patients face during film exposure. Circle or rectangle |
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Extension arm |
The site between the tube head and control panels is enclosed in the collie extension arm. This arm also has an important function in positioning the tube head. Can be turned 360 degrees horizontally. (Side to side as well as vertically(up/down) the arm fold up and can be swiveled. NEVER leave arm in extended position when machine is not in use because weight wears it down and cause it to drift. Also cause a cone cut if damaged meaning it can ruin the picture. |
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Position indicator device(PID) |
The lead lined PID is used to rain the X-ray beam at the film in the patients mouth. Open end is placed close to patients face during film exposure. Circle or rectangle |
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Extension arm |
The site between the tube head and control panels is enclosed in the collie extension arm. This arm also has an important function in positioning the tube head. Can be turned 360 degrees horizontally. (Side to side as well as vertically(up/down) the arm fold up and can be swiveled. NEVER leave arm in extended position when machine is not in use because weight wears it down and cause it to drift. Also cause a cone cut if damaged meaning it can ruin the picture. |
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Control panel |
Located on a wall outside the X-ray area to prevent radiation exposure to the operator while the film is exposed. The control panel contains the master switch, indicator light, selector buttons and exposure button. Selector button is used to select exposure time (Ma) and (KV) thereby regulating the X-ray beam. A single centrally located control panel may be used to operate several tube heads located in separate treatment rooms. |
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Master switch and indicator lights |
Master switch is to turn the machine on/off An orange indicator light shows with the switch is on. The machine can be left on all day because it does NOT produce radiation unless exposure button is pushed. The red emission light comes on only when exposure button is being pushed and X-rays are being emitted. |
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Exposure button |
Controls the flow of electricity to generate the X-rays. Timer is electronically controlled to provide the precise exposure time and X-rays and generated only while the exposure timer is pressed. Exposure time is measure in fractions of a second called impulses ( 60 impulses = 1 second or 30 impulses = .5 of a second) |
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Exposure button |
Controls the flow of electricity to generate the X-rays. Timer is electronically controlled to provide the precise exposure time and X-rays and generated only while the exposure timer is pressed. Exposure time is measure in fractions of a second called impulses ( 60 impulses = 1 second or 30 impulses = .5 of a second) |
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Milliamperage selector (mA) |
Measure of electrical current that passes through the tungsten filament. Controls the number of electrons produced. Increasing then increases the quantity of electrons available for the production of X-rays. |
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Exposure button |
Controls the flow of electricity to generate the X-rays. Timer is electronically controlled to provide the precise exposure time and X-rays and generated only while the exposure timer is pressed. Exposure time is measure in fractions of a second called impulses ( 60 impulses = 1 second or 30 impulses = .5 of a second) |
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Milliamperage selector (mA) |
Measure of electrical current that passes through the tungsten filament. Controls the number of electrons produced. Increasing then increases the quantity of electrons available for the production of X-rays. |
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Kilovoltage (kvp) |
Used to control the power of the X-ray beams. Normally 70-90. |
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Exposure button |
Controls the flow of electricity to generate the X-rays. Timer is electronically controlled to provide the precise exposure time and X-rays and generated only while the exposure timer is pressed. Exposure time is measure in fractions of a second called impulses ( 60 impulses = 1 second or 30 impulses = .5 of a second) |
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Milliamperage selector (mA) |
Measure of electrical current that passes through the tungsten filament. Controls the number of electrons produced. Increasing then increases the quantity of electrons available for the production of X-rays. |
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Kilovoltage (kvp) |
Used to control the power of the X-ray beams. Normally 70-90. |
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X-ray production |
When the X-ray machine is plugged in and the machine is one the electrical current enters control panel and the following things occur instantly - current travels from control panel to the tube head through electrical wires in the arm - the currents travel through the step down transformer to the filament or the cathode. The purpose of step down transformer is to decrease the voltage from the incoming 110-220 volts to 3-5 volts The 3-5 is used to hear the tungsten filament in the cathode potion of the X-ray tube. Results in thermionic emission ( release of elections from the tungsten when the electrical current passes through it heats up. The electrons stay in a cloud around the tungsten within the focusing up until high voltage is activated by pushing the exposure buttons after exposure button is pushed X-rays are produce in an instant in the following way. Push button activates high voltage Circuit. The electrons in the cloud are shot across the X-ray tube to the anode. The molybdenum cup in the cathode directs the electrons to the tungsten target in the anode. The electrons speed from the cathode to the anode. When the electrons trike the target their energy of motion creates X-ray and heat. Less than 1% of the energy is converted to the X-rays with 99% lost as heat. The heat is carried away from the copper stem and is absorbed by insulating oil in the tube head. The X-rays travel through unleaded glass window of the tube, tube head seal, aluminium filter. The aluminum removes longer wavelength X-rays from the beam. The X-ray beam then travels through the collimator where it’s size is restricted. It travels down the PID and exits at opening |
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Types of radiation |
Primary, secondary and scatter Primary - made up of the X-rays that come from the target of the X-ray sometimes referred to as useful beam - comes in contact with patients tissue Secondary - refers to x radiation that is created when primary beam interacts with matters - not useful - creates fog on radiographs Scatter is a form of secondary that occurs when X-ray beam has been deflected from its path though interaction with matter. Deflected in all directions by patients tissues and travel to all parts of body and to all areas of dental clinic. Dangerous to patient and operator |
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Radiolucent and radiopaque characteristics |
Body structures that radiation can easily pass through is dark (radiolucent) - air spaces, soft tissues, abscess, tooth decay, pulp Body structures that radiation do not easily pass through appear white/light grey (radio plaque) - enamel, dense areas of bone, restorations |
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Radiolucent and radiopaque characteristics |
Body structures that radiation can easily pass through is dark (radiolucent) - air spaces, soft tissues, abscess, tooth decay, pulp Body structures that radiation do not easily pass through appear white/light grey (radio plaque) - enamel, dense areas of bone, restorations |
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Characteristics of X-ray beam |
Quality, quantity, intensity These characteristics determine the contrast, density, image details. Required for a good radiograph |
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Radiolucent and radiopaque characteristics |
Body structures that radiation can easily pass through is dark (radiolucent) - air spaces, soft tissues, abscess, tooth decay, pulp Body structures that radiation do not easily pass through appear white/light grey (radio plaque) - enamel, dense areas of bone, restorations |
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Characteristics of X-ray beam |
Quality, quantity, intensity These characteristics determine the contrast, density, image details. Required for a good radiograph |
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Quality |
Used to describe the energy penetrating ability of the X-ray beam. Quality/wave length and energy of the X-ray are determined by kilovoltage 85-100 produces more penetrating X-ray with more energy and shorter wavelengths . The use of 65-75 produces less penetrating dental X-rays with less energy and longer wavelengths. High should be used when the area is dense or thick. Density is the overall darkness or blackness of a image. A chance in KP results in a change in the density |
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Radiolucent and radiopaque characteristics |
Body structures that radiation can easily pass through is dark (radiolucent) - air spaces, soft tissues, abscess, tooth decay, pulp Body structures that radiation do not easily pass through appear white/light grey (radio plaque) - enamel, dense areas of bone, restorations |
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Characteristics of X-ray beam |
Quality, quantity, intensity These characteristics determine the contrast, density, image details. Required for a good radiograph |
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Quality |
Used to describe the energy penetrating ability of the X-ray beam. Quality/wave length and energy of the X-ray are determined by kilovoltage 85-100 produces more penetrating X-ray with more energy and shorter wavelengths . The use of 65-75 produces less penetrating dental X-rays with less energy and longer wavelengths. High should be used when the area is dense or thick. Density is the overall darkness or blackness of a image. A chance in KP results in a change in the density |
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Quality |
Refers to the number of X-rays produce in the dental X-ray unit. The ampere (A) is the unit of measurement used to describe the number of electrons or current following through the cathode filament. Because the number of amperes needed to operate the dental X-ray unit is very small. 1/100 of a A |
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Radiolucent and radiopaque characteristics |
Body structures that radiation can easily pass through is dark (radiolucent) - air spaces, soft tissues, abscess, tooth decay, pulp Body structures that radiation do not easily pass through appear white/light grey (radio plaque) - enamel, dense areas of bone, restorations |
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Characteristics of X-ray beam |
Quality, quantity, intensity These characteristics determine the contrast, density, image details. Required for a good radiograph |
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Quality |
Used to describe the energy penetrating ability of the X-ray beam. Quality/wave length and energy of the X-ray are determined by kilovoltage 85-100 produces more penetrating X-ray with more energy and shorter wavelengths . The use of 65-75 produces less penetrating dental X-rays with less energy and longer wavelengths. High should be used when the area is dense or thick. Density is the overall darkness or blackness of a image. A chance in KP results in a change in the density |
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Quality |
Refers to the number of X-rays produce in the dental X-ray unit. The ampere (A) is the unit of measurement used to describe the number of electrons or current following through the cathode filament. Because the number of amperes needed to operate the dental X-ray unit is very small. 1/100 of a A |
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Intensity |
Intensity is the combo of the number of X-ray photons (quantity) and energy of each photon (quality) the intensity of the beam is affected by a number of factors including the kilo park, milliamperes , exposure time and distance |
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Contrast |
Contrast the image on the radiograph appears in a range of shades from black to white also known as the grey scale. The range of shades is called contrast. The ideal contest of a fun clearly shows the radio plaque white or a metal restoration and black of air and the many shades of grey between these extremes. Higher the kilo produces more penetrating photos and lower contrast as follows 90kvp setting requires LESS exposure time and produces an image with low contrast (more grey) 70kvp setting requires a slightly longer exposure time and produces image with high contrast (fewer shades of grey) The amount of contest in a fil often reflects the dentists preference. Some dentist prefer low well others prefer high |
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Contrast |
Contrast the image on the radiograph appears in a range of shades from black to white also known as the grey scale. The range of shades is called contrast. The ideal contest of a fun clearly shows the radio plaque white or a metal restoration and black of air and the many shades of grey between these extremes. Higher the kilo produces more penetrating photos and lower contrast as follows 90kvp setting requires LESS exposure time and produces an image with low contrast (more grey) 70kvp setting requires a slightly longer exposure time and produces image with high contrast (fewer shades of grey) The amount of contest in a fil often reflects the dentists preference. Some dentist prefer low well others prefer high |
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Density |
Overall blackness or darkness to film. An image with correct enables the dentist to view black areas, white areas, and gray areas. The degrees is controlled by the amperes which control the amount of time given to exposure of the image To short = not correct overall density or will be light in appearance Other factors include distance from X-rays, developing time, body size of patient A patient who is small or thin requires less radiation then a heavy person If processing time is to long the image will appear dark |
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Table 38.2 |
Back (Definition) |
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Geometric characteristics |
3 that affect quality of an image are sharpness, magnification, distortion. Sharpness refers to how well an in image reproduces the tube details or distinct outlines of an object - fuzzy or blurred areas called penumbra. Sharpness if influenced by focal spot size as small is better, film composition as fast film results in less sharp detail, movement of patient or image no matter how slight will degrade the sharpness. Distortion refers to the disproportionate change in the size of image that is caused by excess or insufficient vertical angularion. Magnification refers to proper image enlargement or a dental image |
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Geometric characteristics |
3 that affect quality of an image are sharpness, magnification, distortion. Sharpness refers to how well an in image reproduces the tube details or distinct outlines of an object - fuzzy or blurred areas called penumbra. Sharpness if influenced by focal spot size as small is better, film composition as fast film results in less sharp detail, movement of patient or image no matter how slight will degrade the sharpness. Distortion refers to the disproportionate change in the size of image that is caused by excess or insufficient vertical angularion. Magnification refers to proper image enlargement or a dental image |
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Radiation effects |
All ionizing radiation is harmful and produces biological changes in living tissue. The amount of x radiation used in dental is small, biologic changes do occur. Radiation hazard sign must be uo |
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Tissue damage |
In dental radiography not all X-rays pass through the patient and reach film. The patients tissue DOES absorb some X-rays. When the energy from the X-ray photon is another chemical changes result in bio changes |
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Ionization |
Results in harmful effect of X-rays in humans. Can cause distribution of cellar metabolism and permanent damage to living cells and tissues. Atoms that lose electrons become positive ions as such that are unstable structures capable of damaging atoms, tissues, chemicals |
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Ionization |
Results in harmful effect of X-rays in humans. Can cause distribution of cellar metabolism and permanent damage to living cells and tissues. Atoms that lose electrons become positive ions as such that are unstable structures capable of damaging atoms, tissues, chemicals |
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Bio effects |
Exposure to radiation can bring changes in the body chemicals, cells, tissues, and organs. The effects of radiation may not become obvious for many years. |
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Cumulative effect |
Exposure to radiation can have a cumulative effect |
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Cumulative effect |
Exposure to radiation can have a cumulative effect |
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Acute vs chronic exposure |
Acute - when a large dose is absorbed in a short period Chronic - short doses over time |
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Cumulative effect |
Exposure to radiation can have a cumulative effect |
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Acute vs chronic exposure |
Acute - when a large dose is absorbed in a short period Chronic - short doses over time |
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Genetic and somatic effect |
Genetic cells are the reproductive and is passed on to succeeding generations - genetic mutations All other cells in body belong to somatic tissue. X rays can damage but not passed on. |
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Relative radiation sensitivity of cells and tissues |
Back (Definition) |
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Disorders |
Back (Definition) |
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Critical organs |
Although dental X-ray risk is low some tissues and organs are exposed to more radiation when images are exposed. The following organs are more sensitive. Skin Thyroid gland - if collar wasn’t used especially children’s Lens of eye Bone marrow |
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Radiation measurement |
Traditional or standard style Traditional is units of radiation measurement include 1. Reontgen(R) 2. Radiation absorbed dose (RAD) and 3. Equivalent in hu man (REM) so R RA REM Standard is (c/kg) (gy) (Sv) |
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Max permissible dose |
Denuded by the National Council of Radiation Protection and Measurements NCRP O.5 occupation 0.1 non |
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Max permissible dose |
Denuded by the National Council of Radiation Protection and Measurements NCRP O.5 occupation 0.1 non |
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Radiation safety |
We are exposed to radiation every day of our lives. Black ground radiation comes from natural sources Radioactive materials in the ground Cosmic from space |
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Units of radiation measurement |
Exposure - C/KG or R - 1kg = 3380R Dose - Gy or Rad - 1gy = 100 rad Dose equivalence - SV or Rem - 1sv = 100 rem |
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Radiation sources/exposure |
Back (Definition) |
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Protective devices |
Aluminum filter - removes low energy long wave lengths least penetrating crisis from the beam Collimator - restricts the size and shape of beam to reduce exposure PID - directs beam in round or rectangle shape to one spot - 8,12,16 inches |
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Patient protection |
Lead apron and thyroid collar Fast speed film Image receptor/ holding device - keeps patients hands and fingers from being exposed. Holds image receptor in stable position and assist operator in position of PID Exposure factor - using proper factors also limits amount expose to patient Proper technique |
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Criteria for radiograph |
Back (Definition) |
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Pregnancy |
Don’t need to be altered for pregnancy due to lead aprons but some dentists still prefer not to |
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Rules of radiation protect |
Never stand in direct line of primary beam Always stand behind lead barrier or proper thickness of drywall if not available stand at a right angle to beam Never stand closer than 6 feet unless behind barrier |
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Radiation monitoring |
Dosimeters are used to measure amount of exposure 3 Styles are film badge, pockets of the thermoluminescent device |
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Equipment monitoring |
Machines must be monitors for leakage or any radiation that is emitted from tube head. |
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Paediatric patients |
Parents can hold child if needed but both must have protective gear on |
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ALARA concept |
All exposure to radiation must me kept to a min |
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Good job |
Good job |
