Radiology Lecture 19.docx

Lecture 19 Chapter 17: Quality Assurance in the Dental Office Quality assurance refers to special procedures that are used to ensure the production of high-quality diagnostic images. A quality assurance plan includes both quality control tests and quality administration procedures Quality contro...

Lecture 19 Chapter 17: Quality Assurance in the Dental Office Quality assurance refers to special procedures that are used to ensure the production of high-quality diagnostic images. A quality assurance plan includes both quality control tests and quality administration procedures Quality control tests are necessary to monitor dental x-ray machines, dental x-ray film, screens and cassettes, and viewing equipment. To produce diagnostic-quality images consistently, dental x-ray equipment and supplies must always function properly and be kept in good repair. All dental x-ray machines must be inspected and monitored periodically. A qualified technician must calibrate dental x-ray equipment to ensure consistent x-ray machine performance and the production of diagnostic radiographs. The calibration test checks kilovoltage and milliamperage readings, checking that the x-ray machine is working correctly. The American Academy of Oral and Maxillofacial Radiology (AAOMR) recommends a number of annual tests for dental x-ray machines. The dental x-ray film must be properly stored, protected, and used before the expiration date. For quality control purposes, when each box of film is opened, it should be tested for freshness. Fresh Film Test 1. Prepare the film. Unwrap one unexposed film from a newly opened box. 2. Process the film. Use fresh chemicals to process the unexposed film. • Fresh film. If the processed film appears clear with a slight blue tint, the film is fresh and has been properly stored and protected. Proceed with the use of this film. • Fogged film. Film that has expired, has been improperly stored, or has been exposed to radiation appears fogged. If the film is fogged, it should not be used. Screens should be cleaned on a monthly basis with commercially available cleaners recommended by the screen manufacturer. After the screen is cleaned, an antistatic solution should be applied to it. Screens that have scratches or visible wear should be replaced. Screen-film Contact Test 1. Load the cassette. Insert one film between the screens in the cassette holder and close. 2. Place test object. Place a wire mesh test object on top of the loaded cassette. 3. Position the PID. Position the position-indicating device (PID) using a 40-inch target-receptor distance while directing the central ray perpendicular to the cassette. 4. Expose the cassette. Expose the cassette using 10 mA, 70 kV, and 0.25 seconds. 5. Process the film. Process the exposed film 6. View. Check the film on a viewbox in a dimly lit room at a distance of 6 ft. • Adequate contact. If the “wire mesh” image seen on the film exhibits a uniform density, good screen-film contact has taken place. Proceed with cassette and screen use. • Inadequate contact. If the wire mesh image seen on the film exhibits varying densities, poor screen-film contact has taken place. Areas of poor screen-film contact appear darker than good contact areas. Cassettes that provide inadequate screen-film contact must be repaired or replaced. This test is used to check the extraoral film cassette holder. View box The view box should emit a uniform and subdued light when it is functioning properly. Permanently discolored Plexiglas surfaces must be replaced. Any blackened fluorescent lightbulbs must also be replaced. Light Leak Test 1. Prepare the darkroom. Close the darkroom door, and turn off all lights, including the safelight. 2. Examine the darkroom. Once your eyes become accustomed to the darkness, observe the areas around the door, the seams of the walls and ceiling, the vent areas, and the keyhole for light leaks. • No light leaks. If the darkroom is light-tight, no visible light is seen. Proceed with film processing. • Light leaks. Light leaks, if present, are seen around the door, through the seams of the walls or ceiling, or through a vent or keyhole. Light leaks must be eliminated by using weather stripping or black tape before proceeding with film processing. Safe Light Test (Coin Test) 1. Prepare the darkroom. Turn off all the lights in the darkroom, including the safelight. 2. Prepare the film. Unwrap one unexposed film. Place it on a flat surface at least 4 feet from the safelight. Place a coin on top of the film. 3. Turn on the safelight. Allow the film and the coin to be exposed to the safelight for 3 to 4 minutes. 4. Process the film. Remove the coin, and process the film. Automatic Processor Test 1. Prepare the films. Unwrap two unexposed films; expose one to light. 2. Process both films in the automatic processor. • Functioning processor. If the unexposed film appears clear and dry, and if the film exposed to light appears black and dry, the automatic processor is functioning properly. Proceed with processing. • Nonfunctioning processor. If the unexposed film does not appear clear and dry, and if the exposed film does not appear completely black and dry, the processing solutions and dryer temperature must be checked. Corrections must be made before proceeding with processing. An easy way to check the strength of the developer solution is to compare film densities to a standard. One of the following tests can be used: • Reference radiograph • Step wedge radiographs • Normalizing device Reference Radiograph 1. Prepare the film. Use fresh film to make a reference radiograph. Place an aluminum step wedge on top of the film. 2. Expose the film, using correct exposure factors. With INSIGHT film, use 65 kV, 7 mA, and an exposure time of 0.13 to 0.14 seconds. 3. Process the film, using fresh chemicals (fixer and developer) at the recommended time and temperature. • Matched densities. If the densities seen on the reference radiograph match the densities seen on the daily radiographs, the developer solution strength is adequate. Proceed with processing. • Unmatched densities. If the densities seen on the daily radiographs appear lighter than those seen on the reference radiograph, the developer solution is either weak or cold. If the densities seen on the daily radiographs appear darker than those seen on the reference radiograph, the developer solution is either too concentrated or too warm. Weakened or concentrated developer solution must be replaced. If the developer solution is too cool or too warm, the temperature must be adjusted. A step wedge is a device constructed of layered aluminum steps. When a step wedge is placed on top of a film and then exposed to x-rays, the different steps absorb varying amounts of x-rays. When processed, different film densities are seen on the dental radiograph as a result of the step wedge  Step wedge Radiographs 1. Prepare the films. Use a total of 20 fresh films to create a 1-month supply of films for daily testing. Place an aluminum step wedge on top of one film. 2. Expose the film. Repeat with the remaining films using the same step wedge, same target-receptor distance, and same exposure factors. With INSIGHT film, use 65 kV, 7 mA, and an exposure time of 0.13 to 0.14 seconds. 3. Using fresh chemicals, process only one of the exposed films. This processed radiograph is known as the standard step wedge radiograph. 4. Store the remaining 19 exposed films in a cool, dry area protected from x-radiation. 5. Each day, after the chemicals have been replenished, process one of the exposed step wedge films. This film is known as the daily radiograph. 6. View the standard radiograph and the daily radiograph side by side on a step wedge. Compare the densities seen on the daily radiograph with the densities seen on the standard radiograph. • Matched densities. Use the middle density seen on the standard step wedge radiograph for comparison. If the density seen on the standard radiograph matches the density seen on the daily radiograph, the developer solution strength is adequate. Proceed with processing. Unmatched densities. If the density on the daily radiograph differs from that on the standard radiograph by more than two steps on the step wedge, the developer solution is depleted. The developer solution must be changed before proceeding with processing. • Proper step wedge. If no visible image is seen on the processed film, the safelight is correct. Proceed with film processing. • Improper step wedge. If the image of the coin and a fogged background appear on the processed film, the safelight is not safe to use with that type of film. To avoid step wedge problems, the dental radiographer must use the film manufacturer’s recommended safelight filters and bulb wattages. In addition, the film must be unwrapped at least 4 feet away from the safelight. Step wedge problems must be corrected before proceeding with film processing. WHAT TECHNIQUES ARE USED TO TEST DEVELOPER STRENGTH? REFERENCE RADIOGRAPH, STEP WEDGE RADIOGRAPH, NORMALIZING TECHNIQUE When the fixer solution loses strength, the film takes a longer time to clear or becomes transparent in the unexposed areas. When the fixer is at full strength, a film should clear within 2 minutes, without agitation. Clearing Test. 1. Prepare the film. Unwrap one film and immediately place it in the fixer solution. 2. Check the film for clearing. Measure the amount of time the film takes to clear. • Fast clearing. If the film clears in 2 minutes, the fixer is of adequate strength. Proceed with processing. • Slow clearing. If the film is not completely clear after 2 minutes, reimmerse it in the fixer solution. If the film does not completely clear in 3 to 4 minutes, the fixer solution is depleted. The fixer solution must be replaced before proceeding with processing. WHAT DOES THE CLEARING TEST MONITOR? FIXER STRENGTH Digital Imaging Performance testing and monitoring of digital imaging equipment must be done in accordance with equipment manufacturer specifications. Quality Administration Procedures A record-keeping log of all quality control tests, including the specific test performed, the date performed, and the test results, should be carefully maintained and kept on file in the dental office. In addition, a log for processing solutions, which lists the dates of solution replacement, replenishment, and processor or tank cleaning, should be maintained. A written plan for the periodic evaluation and revision of the existing quality assurance program should also be part of the quality administration plan.  Retakes should be monitored and kept in a retake log to identify recurring problems and to improve the quality of images. Chapter 30: Introduction to Image Interpretation Image interpretation is an essential part of the diagnostic process. The ability to evaluate and recognize what is revealed by a dental image enables the dental professional to play a vital role in the detection of those diseases, lesions, and conditions of jaws that cannot be identified clinically.  Interpret: To offer an explanation. Interpretation: An explanation. Image interpretation: An explanation of what is viewed on a dental image; the ability to read what is revealed by a dental image. Diagnosis: The identification of a disease by examination or analysis. In the dental setting, the dentist is responsible for establishing a diagnosis. All dental images must be carefully reviewed and interpreted. A great deal of information about teeth and supporting bone is obtained from interpretation. Consequently, image interpretation is of paramount importance to the dental professional. The dental radiographer plays an important role in the preliminary interpretation of dental images. The dental radiographer acts as an additional pair of eyes examining the images and can direct the attention of the dentist to any areas of question or concern. To interpret images, the dental radiographer must be confident in the identification and recognition of the following: • Normal anatomy • Dental restorations, dental materials, and foreign objects • Dental caries • Periodontal disease • Trauma, pulpal lesions and periapical lesions • Lesions of bone and bone anomalies • Common artifacts and errors In the dental setting, the terms interpretation and diagnosis are often confused; it is important to note that these terms have very different meanings and should not be used synonymously.  Interpretation refers to an explanation of what is viewed on a dental image, whereas diagnosis refers to the identification of disease by examination or analysis. In dentistry, a diagnosis is made by the dentist after a thorough review of the medical history, dental history, clinical examination, imaging examination, and clinical or laboratory tests. Although any dental professional with training in interpretation may examine dental images, the final interpretation and diagnosis are the responsibilities of the dentist. Dental hygienists and assistants are restricted by law from rendering a diagnosis. To benefit the patient optimally, dental images must be exposed at the beginning of the dental appointment, mounted, interpreted, and then used for diagnostic, therapeutic, and educational purposes. Ideally, dental images should be reviewed and interpreted immediately after placement in a mount, and in the presence of the patient. Digital images are typically viewed by the dental professional on a computer monitor in the operatory. Mounted dental radiographs are usually examined on the viewbox in the operatory and are best interpreted in a room with dimmed lighting All dental images must be reviewed and interpreted. The interpretation must be documented in the patient record and include the following: • Date of exposure • Number and type of images • Evaluation of diagnostic quality • List of limiting factors, retakes, or additional images needed • Description of teeth • Description of bone and supporting structures of the teeth • Description of artifacts • Indication of any areas that require additional imaging or clinic evaluation/confirmation Interpretation of dental images can be used as an educational tool in the professional setting. In addition to providing a preliminary interpretation, the dental radiographer can educate the patient by identifying and discussing what is normally found on a dental image. Chapter 31: Descriptive Terminology. To interpret dental images, the dental professional must be able to describe what is observed in accurate and succinct terms. A working knowledge of descriptive terminology is important for communication and documentation and is essential in interpretation. In dental imaging, a number of different terms can be used to describe the appearance, location, and size of a lesion; these terms represent what is called descriptive terminology. This information should be documented for all lesions viewed on dental images. Descriptive terminology allows dental professionals to intelligently describe and discuss what is seen on dental images and to communicate using a common language. Descriptive terminology also allows the dental professional to document what is seen on a dental image in the patient record in terms of appearance, location, and size. Documentation of what is viewed on dental images is essential for legal purposes. If a notation of interpretation is not included in the patient record, no legal documentation exists that the dental images were reviewed. Descriptive terminology allows the dental professional to describe what is seen on a dental image without implying a diagnosis.  The terms radiolucent and radiopaque are used to describe the appearances of all the structures seen on a dental image. A dental image appears radiolucent (black or dark) where the tissues are soft or thin, and it appears radiopaque (white or light) where the tissues are thick or dense. Most structures do not exhibit uniform thickness and therefore appear gray instead of black or white. Radiolucent refers to that portion of a processed dental image that is dark or black. Dental caries appears radiolucent because the area of tooth with dental caries is less dense than surrounding structures and therefore readily permits the passage of the x-ray beam Radiopaque refers to that portion of a dental image that appears light or white. A metallic restoration appears radiopaque because it is very dense and absorbs the radiation Examples of other radiopaque structures include amalgam, enamel, dentin, and bone. Specific terms are used to describe the appearance of a radiolucent lesion versus the appearance of a radiopaque lesion. In contrast, the terms related to location of a lesion may describe either a radiolucent or a radiopaque lesion, with the exception of alveolar bone loss. The location of a lesion is important for communication and documentation purposes.  In regard to the size of lesions, the preferred unit of measurement is the millimeter or centimeter. Documentation of the size of a lesion is important for treatment considerations as well as for future comparisons.  Terms Used to Describe Radiolucent Lesions The appearance of most radiolucent lesions can be classified as either unilocular or multilocular. Other radiolucent classifications include a “moth-eaten” pattern, a multifocal pattern, or a widened periodontal ligament space Unilocular lesions tend to be small and nonexpansile and have borders that may appear corticated or noncorticated on the dental image. This refers to a radiolucent lesion that exhibits one compartment. A unilocular radiolucent lesion with corticated borders exhibits a thin, well-demarcated radiopaque rim of bone at the periphery. A unilocular corticated lesion is usually indicative of a benign, slow-growing process. Corticated refers to the outer layer or border of a radiolucent lesion. The periphery of a unilocular noncorticated lesion appears fuzzy or poorly defined. A unilocular lesion with noncorticated borders does not exhibit a thin radio­paque rim of bone at the periphery A radiolucency with ill-defined or irregular margins may represent either a benign or malignant process. The term multilocular refers to a lesion that exhibits multiple radiolucent compartments that resemble soap bubbles A multilocular lesion with multiple compartments is typically larger than a unilocular lesion with one compartment. Such a lesion typically exhibits well-defined, corticated margins. A multilocular radiolucent lesion is frequently large and expansile and tends to displace the buccal and lingual plates of bone. The odontogenic keratocyst, ameloblastoma, and the central giant cell granuloma are examples of multilocular radiolucencies viewed on dental images. The term periapical refers to the area around the apex of a tooth  Refers to the terminal end of a tooth root. An example of a common periapical radiolucency is a periapical cyst seen secondary to pulpal necrosis. The term inter-radicular refers to the area between the roots of adjacent teeth An example of a radiolucent lesion found in an inter-radicular location is the lateral periodontal cyst. Edentulous zone refers to an area without teeth.  A variety of radiolucent lesions may occur in an edentulous zone. The term pericoronal refers to the area around the crown of an impacted tooth  A dentigerous cyst is an example of a radiolucent lesion seen in a pericoronal location. Alveolar bone loss refers to loss of maxillary or mandibular bone that surrounds and supports the teeth Alveolar bone loss appears radiolucent. Alveolar bone loss is seen not only with periodontal disease but also with systemic illnesses, such as diabetes, histiocytosis X, and leukemia. Malignant neoplasms may also cause alveolar bone loss. Terms Used to Describe Radiopaque Lesions Radiopaque lesions occur not only in bone but in soft tissue as well. A radiopaque lesion located in soft tissue can be described as a soft tissue radiopacity.  The term focal opacity refers to a well-defined, localized radiopaque lesion on a dental image Condensing osteitis is an example of a radiopaque lesion that can be described as a focal opacity. The term target lesion refers to a well-defined, localized radiopaque area surrounded by a uniform radiolucent halo. A benign cementoblastoma is an example of a radiopacity described as a target lesion. A multifocal confluent radiopaque pattern can be described as multiple radiopacities that appear to overlap or flow together. Diseases such as osteitis deformans and florid osseous dysplasia exhibit a multifocal confluent radiopaque pattern. Multifocal confluent radiopacities that involve multiple quadrants of the jaws usually represent benign fibro-osseous disorders. Irregular radiopacities may represent a malignant condition. May exhibit an irregular, poorly defined pattern Examples of irregular, ill-defined radiopaque lesions include osteosarcoma and chondrosarcoma. A ground glass appearance of bone can be described as a granular or pebbled radiopacity that resembles pulverized glass. A ground glass radiopacity is often said to resemble the texture of an orange peel. Diseases such as fibrous dysplasia, osteitis deformans, and osteopetrosis may exhibit a ground glass or orange-peel appearance. A mixed lucent-opaque lesion exhibits both radiopaque and radiolucent components. Mixed lucent-opaque lesions often represent calcifying tumors. Many such tumors appear as a radiolucent area with central opaque flecks or calcifications. An example of a mixed lucent-opaque lesion is a compound odontoma. A soft tissue opacity appears as a well-defined, radiopaque area located in soft tissue A sialolith (salivary stone) or a calcified lymph node is an example of a soft tissue opacity. Radiopaque lesions can also be described in terms of location. The location of a lesion is important for communication and documentation purposes.  The term periapical refers to the area around the apex of a tooth. An example of a periapical radiopacity is benign cementoblastoma. The term inter-radicular refers to the area between the roots of adjacent teeth. An example of a radiopaque lesion found in an inter-radicular location is sclerotic bone. The term edentulous zone refers to an area without teeth; an example of a radiopaque lesion in an edentulous zone is complex odontoma. A variety of radiopaque lesions may occur in an edentulous zone. The term pericoronal refers to the area around the crown of an impacted tooth. An adenomatoid odontogenic tumor is an example of a mixed lucent-opaque lesion seen in a pericoronal location. Radiopaque lesions can vary in size from several millimeters to several centimeters in diameter and can be easily measured on a dental image with a ruler. Documentation of the size of a lesion is important for treatment decisions as well as for comparative purposes.

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