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VDI #1 Exam #2
Diagnostic Imagining Exam #2 Weeks 4-7
| Question | Answer |
|---|---|
| X-Rays are capable of penetrating what types of materials? | Tissues thru which the rays can pass |
| True or False: X-Rays are visible. | False |
| The source of the x-rays used in radiology is: | the x-ray tube |
| List the steps that occur in the x-ray tube to produce an x-ray. | 1. Filaments heat up->2.Release electrons->3.accelerate toward the anode->4. exit tube verticle as an x-ray beam |
| What does the "kilovoltage" control? | Kilovoltage peak or kVp |
| What does the "milliamperage" control? | Milliamperage Per Second |
| Why is tungsten used as a target material? | Its very heat tolerant |
| Describe the difference between the stationary anode and the rotating anode. | SA=>fixed RA=>rotates on a spindle to allow for distribution of heat |
| What is the "heel effect" and how does it affect radiographs? | When all the energy paced in rapidly moving electrons comes to an abrubt stop when encountering the target in the x-ray tube. |
| What is scatter radiation? | Produced by x-ray beam bouncing off the patient. |
| Why is scatter radiation a concern? | It bounces back up off of the patient, frequently into the area where the x-ray tech is restraining animal. |
| How can scatter radiation be reduced? | Standing uprigh position and turn face away while beam is on. |
| What are 3 variables to be set to create/provide a diagnostic radiograph? | milliamperage, exposure time and kilovoltage |
| The milliamperage setting will control the number of x-rays produced. What would the result be if you increase the mA? What about if you decrease the mA? | Radiographic density-film blackness is increased. A reduction in radiographic density= lighter film |
| How does the exposure time effect the amount of electrons produced? | Is how long the anode is positively charged. The longer the exposure time, the more electrons flow to the anode. |
| Why should you always use the highest mA setting and the lowest time setting available when calculating mA's? | to take a quick and clear x-ray |
| Calculate mA's for the following: a. 20mAx 1/2 sec=______ mAs b. 100 mA x 1/10 sec = ______ mAs c. 1000 mA x 1/10 sec= _______mAs d. 300 mAx 1/160 sec = ______mAs | A. 10 mAs B. 10 mAs C. 100 mAs D. 48 mAs |
| How does the kilovotage affect eh quality of a radiograph? | regulates voltage differential applied between the anode and the cathode in the tube. Higher voltage=faster electrons are accelerated and greater energy of x-ray beam. |
| What type of mAs and kVp setting is used for soft tissue radiographic examinations? | |
| What types of settings would you use for bone structure? | the distance between the target in the x-ray tube and the surface of the x-ray detector |
| What is the standard if you increase the FFD? | # of x-rays reaching the film decreases |
| What is the standard if you decrease the FFD? | # of x-rays reaching the film increases |
| How would you increase radiographic density? | turn up mAp or increase kV |
| Radiographic detail | degree of sharpness that defines edge of an aatomic structure |
| Radiographic Contrast | Desnisty or opacity |
| Radiographic density | degree of blackness of the film |
| List factors that may affect radiographic Detail | FFD, Movement, OFD, Size of focal spot |
| Which exposure factor has the greatest influence on radiographic contrast? | Kilovoltage |
| Which exposure factor has the greatest impact on radiographic density? | mAs setting |
| How is the technique of magnification used to produce a diagnostic radiograph? | object is placed halfway between the film and focal spot of x-ray tube to produce a radiograph twice as large as life size |
| X-Ray Cassette | A lightproof encasement designed tohold x-ray film and intesifying screens in close contact. |
| Intensifying screen | Sheets of luminsecent phosphor crystals bound together and mounted on a cardboard or plastic base. |
| Screen Speed | Refers to its ability to convert absorbed x-ray energy into visible light |
| Nonscreen film | film that is more sensititve to ionizing radiation than to fluorescent light |
| Reflective layer | A layer of an intesifying screen that reflects the light from the phosphor layer toward the film |
| Screen film | Film with silver crystals that is more sensitive to fluorescent light emitted from intesifying screens than to ionizing radiation |
| What are the 2 types of cassettes that are used in Vet medicine? | Nonscreen cassette or direct-exposure in a cardboard cassette Image intesifying screen in a rigid cassette |
| Which of the 2 cassette types is most common? | image intesifying screen in a rigid cassette |
| What are the benefits of using intesifying screens? | 1. It prolongs the life of the tube 2. decreases the amount of exposre to patients and technicians 3. Reduces the risk of patient motion |
| how often should intesifying screens be cleaned? | At least once a month |
| What is the normal life span of a rare earth screen? | 10-12 years |
| True or False: Nonscreen film requires greater exposure. | True |
| T or F: Screen film is more sensitive to ionizing radiation. | F |
| T or F: Nonscreen film produces poorer detail. | F |
| T or F: Nonscreen film is highly sensitive to fluorescent light emitted from intesiifying screens. | F |
| Describe the components of x-ray film | Light sensitive emulsion containing silver halide crystals. |
| Can you use any combination of intesifying screens and x-ray film? Why or why not? | No- size |
| What is film latitude? | The exposure range of a film that iwll produce acceptable densities. |
| How should unexposed film be stored and handled? | Stored verticle so no pressure spots Store in low humidity and cool area Store away from radiation, vapors, formalin, peroxide, or ammonia Handle on edges only |
| A processed film that has not been exposed to ionizing radiation or visible light will apear? | Black |
| Which of the film-screen systems is most commonly used in vet medicine? | Medium Speed or par speed. |
| What is a Technique chart and how is it used in radiography? | provides suggested exposure factors to use based on the anatomic part being radiographed, the thickness of the tissue, and the position of the patient |
| What is Santes' rule? How does it apply to producing a radiograph? | alternative method of developing a variable kV technique chart. useful only if mA and time factors are limited on the radiography unit and only on a single phase unit |
| What is the formula for Santes' rule? | (body measurement in cm) x2=_______+(sid+grid factor) |
| How is a technique chart created? | Trial and error |
| What factors will influence the technique chart? | types of cassette and intesifying screen, type of x-ray film and FFD must be consistant |
| What type of patient should be used for creating a technique chart? | Cooperative or sedated adult dog moderate size (50 lbs) and muscle clean and coat should be either medium or short |
| Any body part exceeding this measurement requires the use of a grid to reduce fog-producing scatter radiation? | 10cm |
| If an initial radiograph is too light, how should the kVp and mAs be adjusted? | increase kVp by 10-15% or increase mAs by 30-50% |
| If the initial radiograph is too dark, how should the kVp and mAs be adjusted? | decrease kVp by 10-15% of decrease mAs by 30-50% |
| What is the formula to calculate mAs? | time x MA=mAs |
| What is a Technique chart and how is it used in radiography? | provides suggested exposure factors to use based on the anatomic part being radiographed, the thickness of the tissue, and the position of the patient |
| What is Santes' rule? How does it apply to producing a radiograph? | alternative method of developing a variable kV technique chart. useful only if mA and time factors are limited on the radiography unit and only on a single phase unit |
| What is the formula for Santes' rule? | (body measurement in cm) x2=_______+(sid+grid factor) |
| How is a technique chart created? | Trial and error |
| What factors will influence the technique chart? | types of cassette and intesifying screen, type of x-ray film and FFD must be consistant |
| What type of patient should be used for creating a technique chart? | Cooperative or sedated adult dog moderate size (50 lbs) and muscle clean and coat should be either medium or short |
| Any body part exceeding this measurement requires the use of a grid to reduce fog-producing scatter radiation? | 10cm |
| If an initial radiograph is too light, how should the kVp and mAs be adjusted? | increase kVp by 10-15% or increase mAs by 30-50% |
| If the initial radiograph is too dark, how should the kVp and mAs be adjusted? | decrease kVp by 10-15% of decrease mAs by 30-50% |
| What is the formula to calculate mAs? | time x MA=mAs |
| What is screen craze? | Very old screens may result in a white speckled pattern artifact. |
| T or F: Dropping a film cassette on a hard surgace may result in loss of contact between the intesifying screens and film, which will result in a blurred image. | True |
| Intesifying screens | Made of layers of tiny crystals bonded together on a plastic support and convered with a protective coating |
| If a commercially produced screen cleaner is not available to clean intesnsigying screens, what can you use? | 70% alcohol or distilled water |
| The reflective layer of an intesifying screen: | reflects light from the phosphor layer of the screen towards the film |
| A rare earth screen is advantageous for vet radiography as they: | reduce mothion artifacts, require fewer x-rays to produce an image, and reduce patient radiation dose |
| The main disadvantage of rare earth screens is? | cost |
| For trial exposure, a normal dog witha lateral measurement of ____ should be selected. | 11-16 cm |
Created by:
gina.baker
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