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Susan
Chapter 38 Radiography
| Question | Answer |
|---|---|
| ALARA concept | Concept of radiation protection that states that all exposures should be kept “as low as reasonably achievable.” |
| Anode | The positive electrode Consists of a wafer-thin tungsten plate embedded in a solid copper rod Converts electrons into x-ray photons The tungsten target is a focal spot and converts electrons into photons The copper stem dissipates heat away from the t |
| Atom | The basic unit of matter. |
| Bremsstrahlung radiation | “Braking radiation.” The sudden deceleration of electrons as they interact with highly positively charged nuclei. |
| Cathode | The negative electrode Consists of a tungsten wire filament in a cup-shaped holder made of molybdenum Supplies the electrons necessary to generate x-rays The tungsten filament produces electrons when heated The molybdenum cup focuses electrons into a |
| Central ray | X-rays at the center of the beam. |
| Contrast | Differences in degrees of blackness on an image. |
| Control panel | The portion of the x-ray unit that contains the master switch, the indicator light, the selector buttons, and the exposure button. |
| Density | The overall darkness or blackness of an image. |
| Dental radiography | The process of recording images of the teeth and adjacent structures by exposure to x-radiation. |
| Digital imaging | A filmless method of capturing an image and displaying it by using an image receptor, an electronic signal, and a computer to process and store the image. |
| Distortion | Change in the size of an image caused by incorrect vertical angulation. |
| Dose of radiation | The amount of energy absorbed by tissues. |
| Dosimeter | A device used to detect and measure an accumulated dosage of radiation. |
| Electron | A negatively charged particle in the atom. |
| Energy | The ability to do work. |
| Extension arm | Flexible arm that is attached to the x-ray tubehead. |
| Image | Film-based or digitally produced recordings of anatomic structures. |
| Image receptor | A recording medium for an image, normally film, phosphor storage plate (PSP), or a digital sensor. |
| Intensity | The total energy of the x-ray beam. |
| ion | An electrically charged particle. |
| ionization | Process by which electrons are removed from atoms, causing the harmful effects of radiation in humans. |
| ionizing | radiation Radiation that produces ionization, resulting in harmful effects. |
| Kilovoltage peak (kVp) | Highest voltage of x-ray tube used during an exposure and it is used to control the penetrating power of the x-ray beam It is used to control the penetrating power of the x-ray beam. Dental x-ray machines generally operate at 70 or 90 kVp |
| Latent period | Time between exposure to ionizing radiation and appearance of symptoms. |
| Lead apron | Device used to protect the reproductive and blood-forming tissues from scatter radiation. |
| Magnification | The proportional enlargement of an image. |
| Master switch, indicator light, selector buttons, exposure button | Components of control panel. |
| Matter | Anything that occupies space and has form or shape. |
| Milliampere (mA) | One one-thousandth (1/1000) of an ampere; a unit of measurement used to describe the intensity of an electrical current. |
| Penumbra | The blurred or indistinct area that surrounds an image. |
| Personal radiation monitoring badge | A device that measures exposure of personnel to ionizing radiation by measuring the intensity of visible light emitted from a crystal in the detector when heated. The intensity of light emitted is dependent upon the radiation exposure. |
| Photon | A minute (tiny) bundle of pure energy that has no weight or mass. |
| Primary beam | The most penetrating beam produced at the target of the anode. |
| Primary radiation | Same as primary beam. |
| Quality of x-ray beam | The mean energy or penetrating ability of the x-ray beam. |
| Quantity of x-ray beam | The number of x-rays produced in the dental unit; the quantity of x-rays produced is controlled by milliamperage. |
| Radiation | Forms of waves of energy emission through space or material. |
| Radiograph | Image produced on photosensitive film by exposing the film to radiation and then processing it. |
| Radiology | The science or study of radiation as used in medicine. |
| Scatter radiation | A form of secondary radiation that occurs when an x-ray beam has been deflected from its path by interaction with matter. |
| Secondary radiation | X-radiation that is created when the primary beam interacts with matter. |
| Sensor | A solid-state image receptor that contains a silicon chip with an electric circuit. |
| Sharpness | A measure of how well an image reproduces the fine details or outline of an object. |
| Somatic | effects Effects of radiation that cause illness and are responsible for poor health (such as cancer, leukemia, and cataracts) but are not passed on to offspring. |
| Thyroid collar | A flexible lead shield that is placed securely around the neck. |
| Tubehead | The part of the x-ray unit that contains the x-ray tube, the high-voltage and low-voltage transformers, and insulating oil. |
| Tungsten target | A focal spot in the anode. |
| X-radiation | High-energy ionizing electromagnetic radiation. |
| Who discovered x-rays? | Wilhem Conrad Roentgen |
| Who was the first person to make practical use of x-rays in dentistry? | Edmund Kells |
| What is ionization? | The production of removing electrons from atoms, creating ions, and causing harmful effects of radiation in humans |
| What are the primary components of an x-ray machine? | 1.Tubehead 2.Extension arm 3.Control panel |
| Name the negative electrode inside the x-ray tube | Cathode |
| Name the positive electrode inside the x-ray tube | Anode |
| What does the control panel contain? | 1.Master switch 2.Indicator light 3.Selector buttons 4.Exposure button |
| abnormality | something abnormal, usually in the body |
| Cat NAP | Cathode N- Negative A-anode P-positive |
| Wave concept | Shorter wavelengths have greater energy Because of their energy, short wavelengths can penetrate matter more easily More useful, preferred |
| Metal housing | Metal body houses the x-ray tube Filled with insulating oil |
| Tubehead seal | Made of leaded glass or aluminum Keeps the oil in the tubehead, and acts as a filter for the x-ray beam |
| X-ray tube | Produces x-rays |
| Transformer | Alters the voltage of incoming electrical current |
| Aluminum filter/Aluminum disks | aluminum sheet 0.5 mm thick |
| Lead collimator | A metal disc with a small opening in the center, 2” control the size and shape of the x-ray beam as it leaves the tubehead |
| Position Indicating Device/PID | the open-ended, lead-lined cylinder extends from the opening of the metal housing used to aim the x-ray beam |
| A glass vacuum tube | Measures about 6 inches long by 1 inch in diameter Includes: Leaded-glass housing Cathode Anode |
| Leaded-glass vacuum tube | Prevents x-rays from escaping in all directions One area has a “window” that permits the x-ray beam to exit the tube and directs the beam toward the aluminum disks, lead collimator, and PID |
| Position indicator device | Lead-lined cylinder Used to aim the tubehead Placed as close as possible to the patient’s face Cylindrical or rectangular 8 inch or 16 inch in length |
| Exposure Buttons and Selector Buttons | Exposure button controls the flow of electricity to generate the x-rays Exposure time is measured in fractions of a second, called impulses 60 impulses = 1 second; 30 impulses = 0.5 second |
| Types of radiation | Primary radiation Secondary radiation Scatter radiation |
| what is Primary radiation ? Types of Radiation | is made up of the x-rays that come from the target of the x-ray tube. Primary radiation is often referred to as the useful beam |
| What is Secondary radiation? Types of Radiation | X-Radiation that is created when the primary beam interacts with matter it is less penetrating than primary radiation and also not useful radiation because it produces fog on the radiograph, damaging the diagnostic quality. |
| What is Scatter radiation? Types of Radiation | is a form of secondary radiation that occurs when an x-ray beam has been deflected from its path through interaction with matter. it is deflected in all directions by patient tissues and travels to all parts of the patient’s body and to all areas of the d |
| IMAGE CHARACTERISTICS | IS A TERM USED TO DESCRIBE WHAT OBJECTS LOOK LIKE IN A RADIOGRAPHIC IMAGE. |
| What is Radiolucent structures? | Body structures that radiation Can Easily pass through appear radiolucent (dark) on an image. For example, air spaces, soft tissues, abscesses, tooth decay, and dental pulp appear |
| What is Radiopaque structures ? | Body structures that radiation Does Not easily pass through appear radiopaque (white or light gray) on an image For example, tooth enamel, dense areas of bone, and metal restorations |
| RADIOLUCENT | OBJECT THAT ALLOW X-RAYS TO PASS THROUGH. IMAGE APPEARS DARK. |
| RADIOPAQUE | DOES NOT ALLOW X-RAYS TO PASS THROUGH. IMAGE APPEARS LIGHT. |
| Three characteristics of the x-ray beam. | 1-quality, 2- quantity, 3- intensity this alow us to change the image of the radiopaque and the image detail as well |
| DIAGNOSTIC QUALITY IMAGES | DIAGNOSTIC QUALITY IMAGES ALLOW THE DENTIST TO LOOK AT A RADIOGRAPHIC IMAGE AND BE ABLE TO TELL WHAT EVERYTHING IS IN THE IMAGE AND BE ABLE TO MAKE AN ACCURATE DIAGNOSIS. |
| These characteristics determine the contrast, density, and image detail | the qualities necessary for a good image |
| Predetermined settings | Old machines adjusted manually |
| What is quality? | QUALITY IS PENETRATING ABILITY, OR STRENGTH, OR POWER. HOW STRONG IS YOUR BEAM IS DETERMINED BY KV. |
| What are the controlled of The quality or wavelength and energy of the x-ray beam? | They are controlled by kilovoltage. HIGH KILOVOLTAGE = HIGH POWER, STRENGTH, POWER, MORE ENEGRY 85-100 kV produces more penetrating x-rays, more energy, shorter wavelengths 65-75 kV produces less penetrating x-rays, less energy, longer wavelengths |
| when do you need to use A higher kilovoltage? | It should be used when the area to be examined is dense or thick |
| WHAT IS IMGE DENSITY ? | IT IS HOW DARK IS YOUR IMAGE. A DENSE IMAGE IS VERY DARK. AN IMAGE THAT LACKS DENSITY IS TOO LIGHT. The image Too Dark because the quality of the beam too high The image Too Light because the quality of the beam too low |
| What is the number of mA use In dental radiography? | the use of 7 to 15 mA is required; a setting above 15 mA is not recommended because it would cause excessive heat production in the x-ray tube. |
| what is the different between quality and quanlity? | Kv = quaLity mA=Quanlity |
| What is Intensity? | It is Combination of quantity of photons and quality of photon energy |
| What is thh intensity of the x-ray beam is affected ? | Affected by number of factors: Kilovoltage peak Milliamperage Exposure time Distance |
| What is contrast? | The image on a radiograph appears in a range of shades from black to white with multiple shades of grayg. This range is referred to as the gray scale Referred to as grey scale |
| what is HIGH CONTRAST? | HIGH CONTRAST... DARKER BLACK AND LIGHTER WHITE, FEWER SHADES INBETWEEN. HIGH CONTRAST, SHORT SCALE CONTRAST.HIGHER KVP |
| what is LOWER CONTRAST? | LOWER CONTRAST.. BLACK ISN'T AS DARK, WHITE ISN'T AS LIGHT, MORE SHADES OF GREY BETWEEN. LOW CONTRAST, LONG GREY SCALE. LOWER KVP |
| what is the good CONTRAST for image ? | medium of high and lower contrast |
| what is a high number of HIGH CONTRAST? | 90 kVp setting Requires less exposure time Image low contrast More shades of gray |
| what is a lower number LOWER CONTRAST? | 70 kVp Requires more exposure time Image high contrast Fewer shades of gray |
| What is the density image? | is the overall blackness or darkness of a film. An image with the correct density enables the dentist to view black areas (air spaces), white areas (enamel, dentin, and bone), and gray areas (soft tissues). |
| What is controlled the degree of density? | The degree of density is controlled by the milliampere seconds (mAs). |
| what is Correct density enables the dentist to view? | Black areas (air spaces, pulp chamber, abscesses) White areas (enamel, dentin, bone) Grey areas (soft tissues) |
| what are Three geometric characteristics affect image quality? | Sharpness Distortion: Magnification |
| what is Sharpness? | -How well an image reproduces fine detail -Detail, sharpness, or definition -Penumbra |
| what is Penumbra?(important) | Fuzzy or blurred area surrounding an image |
| The sharpness of an image is influenced by the following factors.what is Influencing factors? | Focal spot size Smaller focal spot results in a sharper image Film composition Fast film speed results in less sharp detail Movement Slightest movement of patient, receptor, or PID |
| What the fuzzy or blurred area that surrounds an image is called? | is called penumbra |
| what is Distortion? | refers to the disproportionate change in the size of images that is caused by excessive or insufficient vertical angulation |
| WHat is Magnification? | refers to the proportionate enlargement of a dental image. |
| Name the types of Radiation. | Primary Radiation Secondary Radiation Scatter Radiation |
| Describe the difference between radiopaque and radiolucent. | Radiopaque does not allow passage of x-rays, images appear white/light Radiolucent does allow passage of x-rays, images appear black/dark |
| Give examples of structures that appear radiolucent on a radiograph. | Air space, soft tissues, cavities, abscesses, dental pulp |
| Give examples of structures that appear radiopaque on a radiograph. | Restorations, enamel, dense bone |
| What are the three characteristics of the x-ray beam? | Quality Quantity Intensity |
| Which exposure factor controls contrast? | Kilovoltage |
| What is meant by density on a dental radiograph? | The overall darkness or blackness of a film |
| Radiation effects | All ionizing radiation is harmful and produces biologic changes in living tissue Dental imaging is a low amount, however still harmful Entire x-ray area is a radiation hazard area Proper signage is required |
| ionizing radiation | All ionizing radiation is harmful and produces biologic changes in living tissue Dental imaging is a low amount, however still harmful Entire x-ray area is a radiation hazard area Proper signage is required |
| Tissue damage | Not all x-rays pass through the patient and reach the receptor Patient tissues absorb some x-rays When photon energy is absorbed, chemical changes result in biologic damage |
| ionization | Results in the harmful effects of x-rays in humans Can cause disruption of cellular metabolism and permanent damage to living cells and tissues Atoms that lose electrons become positive ions Unstable structures capable of interacting with and damaging |
| Biologic effects | Exposure can bring changes in body chemicals, cells, tissues, and organs Effects of radiation may not become evident for many years after absorption This is the latent period |
| Cumulative effects | Exposure to radiation has cumulative effect over a lifetime When tissues are exposed, some damage occurs Tissues can repair some damage, tissues do not return to their original state Cumulative effects of radiation can be compared with the cumulative e |
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