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Radiology I
Final Exam Review
| Question | Answer |
|---|---|
| DICOM standards refers to: | The international standard for transmission of medical images. |
| Film Exposure Index is an estimate of: | Technique: x-ray exposure |
| Computed Radiology is susceptible to which artifacts? | Scatter, Movement, Time (fading of unprocessed image) |
| The digital technology we use in our on-campus lab is: | Indirect Digital Radiography - CR - Computed Radiography |
| Digital radiograph image quality is dependent on correct settings for: | mAs |
| Advantages of digital radiographs over traditional screen-film radiography include: | Easier image transport, storage, and ability to alter contrast. |
| True or False: CR resolution is always better than conventional film resolution. | False |
| True or False: Digital radiography has a wide latitude. What does this mean for image quality? | kVp has virtually no effect in image quality. Detail of bone/soft tissue in same exposure. |
| Name three advantages of CR (Computed Radiography) | Existing radiology rooms can use the technology. The learning curve is shorter due to similarities with film radiography. The computer can adjust technique decreasing the need for retakes. (contrast) |
| What is Moire effect? | Caused by interference between frequency of matrix and spiral. |
| The konica system uses an inversely proportional number system from 0 - 2000. "0" represents extreme ______ exposure, while "2000" is ______ detectable exposure. What is the optimal range? ______ being dark and _____ being light. | Extreme over exposure, no detectable exposure, 150 - 300, 150 = dark 300 = light |
| Name six possible CR artifacts: | Fading, light leak, physical damage to image plate (cracks, scuffs, scratches, contamination, dust/dirt). Dirt in reader, Highly sensitive to scatter radiation, upside-down insertion into bucky. |
| True or false: DDR and CR are more sensitive to scatter radiation than film. | True |
| True or False: Film radiography has a narrow latitude. What does this mean in regard to technique. | True: Minor under/over exposure will fail to provide a diagnostic image. Not possible to provide detailed image of bone and soft tissue in same view. |
| What is PACS and what does the acronym stand for? | System that allows storing, retrieving, distributing of digital images throughout your hospital or the internet. Picture Archiving & Communication System |
| X-rays only make shadow images: A small beam = | Sharp shadow. Therefore, for the sharpest image, limit the aperture or "cone down" exposure area. |
| What is the heel effect and how do we compensate for it when radiographing? | Ray intensity is higher closure to the cathode. (Due to the angle of the anode) Placing thicker body parts toward the cathode side (-) of the beam to produce a more uniform image. |
| A matter of principles: What are x-rays? | A form of electromagnetic radiation similar to: gamma rays, radio waves, visible light, T.V. waves. |
| What does the "Exposure Value Indicator" system do? | It will evaluate your technique. Is there enough blackness for the view you are attempting? Exposure indicators: computer assesses background and assigns a number. |
| Hazards of Ionizing Radiation: Name eight tissues that are sensitive to radiation. | GI, bone, lymphatic, dermis, leukopoietic, hemopoietic (blood forming), epithelial tissues, brain, lens of eye |
| How does focal spot size effect detail? | A smaller focal spot = best detail. Can be affected by repeat radiographs heating the anode. |
| Hazards of Ionizing Radiation: What rapidly dividing cells are most sensitive to ionizing radiation damage? | Growth cells, gonad cells, metabolically active cells |
| Holding patients: How do we restrain patients safely? | Lead: gloves, aprons, thyroid shield, leading goggles, keep out of primary beam, use chemical restraint on animals when possible |
| The amount of electrical energy being applied to the filament (the quantity of x-rays produced during exposure) | milliamperage (mA) mA x time (in seconds) = mAs |
| Ionizing radiation dosage is ______? | Cumulative |
| How does radiation negatively affect tissues of the body? | Radiation damages/alters DNA. Permanent mutation of DNA. |
| Lower kVp, higher mAs are used for _______ structures? | bone |
| Higher kVp and lower mAs settings are for ____ tissue? | soft |
| Name four sedatives/anesthetics that have reversal agents available. | Dexmedetomidine (Dexdomitor)- dog (IM, IV) cats (IM), All opiates, Benzodiazepines (Valium), and Xylaxine |
| What is GDV? | Gastric Dilation Volvulus (twisted stomach, gastric torsion) |
| True or False: Never use medical tape on birds | True |
| What are some uses for wooden or lucite spoons? | Flexed view studies of joints. The spoon is used to apply gentle pressure during the image. Useful as a "compression paddle" which enhances detail in specific locations like uterus and urinary bladder. Not advise if may injure: pyometra, cystic mass, etc |
| What is leveling? | Maintaining contrast and adjusting brightness. Density of Brightness |
| Define: windowing | "Grey level mapping," "contrast stretching," "contrast enhancement" Adjustment made to contrast (grayscale) Contrast range of densities |
| Controlling x-ray beam: X-rays _____ _____ be focused by a lens. | can not |
| Artifacts that are created during processing: (list five) | Dark film: poor contrast, Light film: poor contrast, Clear film: not exposed, White lines across film, browning of film |
| Ideal label for film identification is: | Clinic name/veterinarian, patient/owner name, date, species/breed/age/sex, view (for class) |
| Doubling the mAs will have what affect of film exposure. | Doubles it |
| Never place positioning aids _____ or ______ area of interest. Why? | over or under, They are not completely radiolucent |
| Every digital imaging system is equipped with an "Exposure Value Indicator" system. It measures the overall exposure received by the _______ for that particular exposure. | plate |
| Name two disadvantages of CR (Computed Radiography) | Cost of plates is expensive, Increased exposure compared to film and DDR. (2x the mAs) |
| Advantages of DDR - Direct Digital Radiography | No cassette, Image capture device embedded in table-top, increased productivity due to elimination of processing cassette. No film costs. No darkroom space or process maintenance. No films to file or look for. Decreased retakes. Can see image immediately. |
| A quality factor that regulates the energy of the x-ray beam. The higher the ____, the faster electrons are accelerated, the greater energy of the x-ray beam. | kilovoltage (kVp), voltage (force) |
| Technical Factors: Use of a higher _____ with an appropriate reduction in ______ results in less radiation dose. | kVp, mAs kVp must be appropriate for the study. 70 kVp @ 15 mAs = less dose than 60 kVp @ 30 mAs |
| Describe growth plates. | Young animals have areas on joints/bone that look like fractures. Varies with larger breeds. Neuturing accelerates closure. Sexual maturing = growth plate closure. |
| How does DR compensate for radiofrequency interference? | The detector is shielded. |
| Increasing kVp by 20% has what affect on film radiographs? | It doubles blackness of patient image. |
| _____ _____ is the contrast and detail of the image and is controlled by four exposure factors. Name them: | Image Quality: Contrast, mAs & kVp. Detail: Focal film distance (40 inches), Object film distance (as close as possible. Parallel to cassette. Perpendicular to beam. |
| True or false: Different combinations of mA and seconds will equal the same mAs? | True. Which do you choose? Lowest time for most effective image. 300 mA x 1/30 sec = 10 mAs or 100 mA x 1/10 sec = 10 mA. |
| True or false: Digital radiography is particularly sensitive to time and scatter? | True. Process images right away. 3-5 days image will be gone. |
| What are two major types of Digital Radiography receptors? | Computed Radiography (CR), and Direct Digital Radiography (DDR) |
| What is DICOM and what does the acronym mean? | Standardized imaging "language" that allows multiple pieces of equipment to communicate digital images. (Digital Imaging and Communications in Medicine) |
| Exposure Artifact: VERY high exposures can result in saturation. Name four results. | Maximum detector response reached. No response to increased dose. Uniformly dark. Cannot be windowed/leveled |
| Radiographic views: Minimum standard of care? | Two views of any body region. Three views if evaluating lungs for tumors. Recommended: identical views of opposite limb are done for comparison. Smallest image window possible for maximum detail. (cone down) |
| Digital: What are four ways you can reduce scatter that reaches the image plate? | Collimate, Reduce kVp, Air gap technique, add a grid |
| A technique chart has what information on it? | Thickness (cm), Study type (Thorax, Abdomen, Bone), Exposure time (sec), Quantity (mA), Energy setting (kVp), Film type and grid status |
| The radiographic appearance of an object. It is related to how many x-rays can pass through the object. | Opacity |
| What is the period during which x-rays are permitted to leave the x-ray tube called? | Exposure time (in seconds) |
| Hazards of Ionizing Radiation: All living cells are susceptible to ionizing radiation damage. True or false. | True |
| Hazards of Ionizing Radiation: True or False, persons younger than 18 and pregnant women should NOT be actively involved in taking x-rays. | True |
| When unloading film from cassettes, we should avoid using _____, and handle film only at corners/edges to avoid _______ and _______. | Fingernails, fingerprints and creases (from flexing or bending the film) |
| How do x-rays behave? | They travel in straight lines: through water, vacuum, air. Act like waves traveling through space. |
| How do we chose technique? | Measure (twice) expose once Consult chart |
| Setting x-ray technique: How do we measure the patient? | Always use calipers, Measure in correct body position (cat abdomen will be twice as thick in cage -ventral recumbency. Chest should be measured at widest point. Usually 7th rib, behind shoulders. Abdomen measured just behind last rib. |
| True or false: charts should be developed specific to each machine. (and developer) | True |
| What is mAs? | Milliamperage per second. mA x sec = mAs Any combination of mA and seconds that equal the same mAs will appear the same to the eye. In veterinary medicine we generally choose the technique with the shortest seconds to yield the goal mAs due to motion |
| Objects that allow many x-rays to pass through are black. (lungs) This is called: | radiolucent |
| What objects are whiter than bone? | Rocks and Metal |
| What determines exposure and by extension contrast? | mAs and kVp |
| What two exposure factors determine level of contrast? | mAs and kVp |
| What does a diaphragm look like in a radiograph for R lateral? | Creates a parallel line |
| Object - Film Distance: The _____ the object is to the film, the _____ the image. | Closer, sharper |
| Name five radiographic artifact origins (digital or not) | Poor positioning, motion, incorrect patient ID, double exposure, grid cut-off |
| What is latitude? | Exposure parameters that will yield a diagnostic image (shades of gray) |
| How does focal-film distance affect detail? | The closure the film is to the x-ray tube, the more magnification and loss of detail |
| What is an artifact? | Any optical density that is not anatomy. An unwanted density on the radiograph. Interferes with diagnosis. |
| Film Storage Unit: Film must be stored properly to protect it from: (list four) | Light, Heat, Moisture, Radiation |
| What is Uberschwinger Artifacts? | "over shoot" Causes appearance of fine black halo. Result of implementation of edge enhancement. Can be mistaken for evidence of loosening of orthopedic device. Can mimic pneumothorax (collapsed lung) |
| Thoracic Radiographs: Left Lateral | Measuring at highest area........ |
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Raevyn1
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