ARRT practice 2

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ARRT practice 2
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2013-02-19 12:36:06
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  1. The CR should be directed to the center of the part of greatest interest to avoid
    Rotation Distortion

    Image details placed away from the path of the CR will be exposed by more divergent rays, resulting in rotation distortion. This is why the CR must be directed to the midpoint of the part of greatest interest. For example, if bilateral hands are requested, they should be examined individually; if imaged simultaneously, the CR will be directed to no anatomic part (between the two hands) and rotation distortion will occur.Magnification occurs when an OID is introduced, or with a decrease in SID. Foreshortening and elongation are the two types of shape distortion—caused by nonalignment of the x-ray tube, part/subject, and IR.
  2. A film emerging from the automatic processor exhibits excessive density. This might be attributable what?
    Developer temeprature too high and chemical fog because excessive developer temeprature results in exvessive density resulting in chemical fog.

    It also can be caused by over replenishment and faulty microswitches.
  3. The ridge that marks the bifurcation of the trachea into the right and left primary bronchi is the
    Carina.

    Carina: Internal ridge located at the seperation of the trachae into right and left primary bronchi.

    Epiglottis: Flap of elsastic cartilage that prewvents fluids/solids from going on the the respratiory tract.

    Root: Attaches the lunchs to the mediastanum.

    Hilum/Hilus: opening on hte miedial aspect of the lung through which arteries, veins and so forth enter and exit
  4. Which of the following information is necessary to determine the maximum safe kilovoltage using the appropriate x-ray tube rating chart?

    MA and exposure time
    FOcal Spot Size
    Imaging system
    1 and 2 

    Given the milliamperage and exposure time, a radiographic rating chart enables the radiographer to determine the maximum safe kilovoltage for a particular exposure. Because the heat load an anode will safely accept varies with the size of the focal spot and the type of rectification, these variables must be identified. Each x-ray tube has its own radiographic rating chart. The speed of the imaging system has no impact on the use of a radiographic rating chart.
  5. What time would be the safest interval of time for a fertile woman to undergo abdominal radiography without significant concern for irradiating a recently fertilized ovum?
    The first 10 days following the onset of menstruation

    • The most hazardous time for abdominal irradiation is in the earliest stages of pregnancy, when many women are unaware that they are pregnant. For this reason, it is recommended that elective radiologic procedures be performed within the first 10 days following the onset of the menses. It is during this time that the danger of irradiating a recently fertilized ovum is most unlikely. About 14 days before the onset of menses is when the ovarian follicle ruptures and liberates an ovum
    •  
  6. What are photoimers used for?
    To terminate the x-ray exposure once hte IR is correctly exposed.
  7. As grid ratio decreases... what happens to the scale of contrast?
    Scale of contrast becomes longer

     Because lead content decreases when grid ratio decreases, a smaller amount of scattered radiation is trapped before reaching the IR. More grays, therefore, are recorded, and a longer scale of contrast results.Radiographic density would increase with a decrease in grid ratio. Grid ratio is unrelated to distortion.
  8. In what order should the following exams be scheduled?

    Upper GI
    IVP
    Barium Enema
    IVP -> Barium Enema -> Uppper GI

    Because its important ot avoid the possibiltiy of residual contrast medium covering areas of interest on later examinations.

    IVP is first because contrast medium used is excreted rapidly

    BE should be next because any previous barium left should not interfere with the stomach orduodenum images but the contrast from the Upper GI will because it wil lbemaking its way down.
  9. How do you calculate grid ratio?
    Height of lead strip divided by the width of interspace material.

    Example: Height = 5 , width of interspace metarial .5 

    5/.5 = 10

    10:1 grid ratio
  10. To demonstrate esophageal varices, patient must be examined in what position?
    Recumbent position 

    Esophageal varices are tortuous dilatations of the esophageal veins. They are much less pronounced in the erect position and must always be examined with the patient recumbent. The recumbent position affords more complete filling of the veins, as blood flows against gravity
  11. According to The Law Of Bergonie and Tirbondue, which cells are most radiosenseitive?
    Precursor cells found in the bone marrow such as red blood cell precursors ( erythroblasts )

    The least radiosensitive are myeocytes  because they are the most mature
  12. Which of the following delivers the alrgest thyroid dose?

    AP skull
    PA Skull
    PA Esophagus
    PA CHest
    Ap SKull 

     Exposure dose to patients can be expressed as entrance skin exposure (ESE), sometimes referred to as skin entrance exposure (SEE). Exposure can also be expressed in terms of organ dose. Organ doses to the gonads, bone marrow, breast, thyroid, lens, and lung can be determined. Patient position and beam restriction often make a significant difference in patient dose. Examinations performed PA, rather than AP, often decrease exposure to sensitive organs. This is so because the lower energy x-ray photons will be absorbed by the anatomic structures closer to the x-ray source, and the higher energy photons will penetrate and exit the part (penetrating the sensitive part rather than being absorbed by it). PA abdomen radiographs deliver less quantity dose to the reproductive organs than do AP abdomen radiographs. An AP skull projection (80 kVp) delivers about 90 mrad to the thyroid, whereas a PA skull (80 kVp) radiograph delivers 8 mrad; the PA esophagus (110 kVp) radiograph delivers 9 mrad, and the PA chest (120 kVp) radiograph delivers about 1 mrad. (Bontrager and Lampignano, 6th ed., p. 67)
  13. Window width vs window level
    • Windwo width - affects the gray shades.
    • Window level - affects the brightness of the image.
  14. Where is the "sterile corridor" located?
    Between draped patient and instrument table.

    When radiographs in the surgical suite are required, the radiographer is responsible for ensuring that surgical asepsis is maintained. This requires proper dress, cleanliness of equipment, and restricted access to certain areas. An example of a restricted area is the "sterile corridor," which is located between the draped patient and the instrument table and is occupied only by the surgeon and the instrument nurse.
  15. Are anticeptics considered chemical substances htat kill patohgenic bacteria?
    No. Theyre for sterilziation which inhibit hte growth/spread of pathgoenic microorganisms.

    Germicides and iinfectants are specifically used to kill germs.

    Some chemical agents used in health-care facilities function to kill pathogenic microorganisms, while others function to inhibit the growth/spread of pathogenic microorganisms. Germicides and disinfectants are used to kill pathogenic microorganisms, whereas antiseptics (like alcohol) are used to stop their growth/spread. Sterilization is another associated term; it refers to the killing of all microorganisms and their spores. (
  16. Which radiologic examinations can demonstrate ureteral reflux?
    • Voiding cystourethrogram
    • Ureteral reflux is best demonstrated during voiding. It can occur even when the bladder is only partially filled with a contrast medium. Thevesicourethral orifice, as well as other sphincter muscles, relaxes during urination; however, the vesicoureteral orifices may also relax and cause reflux

     
  17. A type of cancerous bone tumor occurring in children and young adults and arising from bone marrow is
    E wing sarcoma

    Ewing sarcoma is a (primary) malignant bone tumor that arises from bone marrow and occurs in children and young adults. The disease is characterized by new bone formation in a layering effect—giving the bone the characteristic "onion peel" appearance radiographically. Multiple myeloma is also a cancerous bone tumor usually affecting adults between the ages of 40 and 70 years. Bone undergoes osteolytic changes, and radiographic demonstration appears as circular areas of bone loss. As their name implies (chondr),enchondroma and osteochondroma involve cartilage—they are both benign conditions
  18. What is the most the most poisterioyl located part of the stomach?
    • Fundus lies posteiroly.
    • Body, pylorus and duodenum angles anteriorly.
  19. For magnification factor, what is the formula?
    How do you get SOD?
    SID/SOD

    SOD = SID-OID
  20. What is anaphylaxis?
    aphylaxis is an acute reaction characterized by the sudden onset of urticaria, respiratory distress, vascular collapse, or systemic shock, sometimes leading to death. It is caused by ingestion or injection of a sensitizing agent such as a drug, vaccine, contrast agent, or food, or by an insect bite.
  21. What is the spinning-top test?
    The spinning-top test is used to evaluate timer accuracy orrectifier failure. With single-phase, full-wave-rectified equipment
  22. Battery powered mobile vs Capacitator-discharge.
    Capacitator-discharge - light and easy to maneuver.

    battery-powereed mobile unit: very heavy but capable of storing a large mas capacity for extended periods of time and have te abiltiy to store enregy for a nextended periods of time.
  23. The type of x-ray tube designed to turn on and off rapidly, providing multiple short, precise exposures, is
    Grid-controlled x-ray tubes.

    X-ray tubes are diode tubes; that is, they have two electrodes—a positive electrode called the anode and a negative electrode called thecathode. The cathode filament is heated to incandescence and releases electrons—a process called thermionic emission. During the exposure, these electrons are driven by thousands of volts toward the anode, where they are suddenly decelerated. That deceleration is what produces x-rays. Some x-ray tubes, such as those used in fluoroscopy and in capacitor-discharge mobile units, are required to make short, precise—sometimes multiple—exposures. This need is met by using a grid-controlled tube. A grid-controlled tube uses the molybdenum focusing cup as the switch, permitting very precise control of the tube current (flow of electrons between cathode and anode)
  24. The most common cause of x-ray tube failure is
    vaporized tungsten on glass envelope.

    • Excessive heat production is a major problem in x-ray production. Of the energy required to produce x-rays, 0.2% is transformed to x-rays, and 99.8% is transformed to heat. The copper anode stem and the oil surrounding the x-ray tube help to move heat away from the face of the anode. Excessive heat can cause pitting of the anode (resulting in decreased output) or actual cracking of the anode or damage to the rotor bearings (resulting in tube failure). As the cathode filament is heated for exposure after exposure, some of its tungsten is vaporized and deposited on the inner surface of the glass envelope near the tube window. After a time, this can cause electric arcing and tube failure. This is the most common cause of tube failure because it can occur even with normal use.
    •  
  25. Which kind of exams would require an increase in exposure factors? Exams that include checking for fluid levels or air levels?
    FLuid levels.
  26. If the quantity of black metallic silver on a particular radiograph is such that it allows 10% of the illuminator light to pass through the x-ray image, that image has a density of
    1.0

    If 10% of the illuminator's light passes through the image, that image has a density of 1. If 1% of the light passes through the image, that image has a density of 2.
  27. For radiographic examinations of the skull, it is generally preferred that the skull be examined in the
    PA projection

     Because the primary x-ray beam has a poly-energetic (heterogeneous) nature, the entrance or skin dose is significantly greater than the exit dose. This principle may be employed in radiation protection by placing particularly radiosensitive organs away from the primary beam. To place the gonads further from the primary beam and reduce gonadal dose, abdominal radiography should be performed in the posteroanterior (PA) position whenever possible. Dose to the lens is decreased significantly when skull radiographs are performed in the PA position.
  28. HOw is blood pressure meassured? Pulse rate? temperature? Respiration?
    • Blood pressure 110–140 mm Hg/60–80 mm Hg
    • Pulse rate 60–100 beats/min
    • Temperature 97.7°F–99.5°
    • FRespiration rate12–20 breaths/min
  29. A controlled area is one that is
    A controlled area is one that is occupied by radiation workers; the exposure rate in a controlled area must not exceed 100 mR/week. Anuncontrolled area is one that is occupied by the general population; the exposure rate must not exceed 10 mR/week. Shielding requirements vary according to several factors, one of them being occupancy factor.
  30. All the following statements regarding CR IPs are true except

    A. IPs do not contain radiographic film.
    B. IPs use no intensifying screens.
    C. IPs must exclude all white light.
    D. IPs function to protect the PSP.
    IPs must exclude all white light.

    • Externally, IPs (Image Plates) appear very much like traditional film–screen cassettes. However, the main function of an IP is to support and protect the PSP (SPS) that lies within the IP. IPs do not contain intensifying screens or film and, therefore, do not need to be lighttight. The photostimulable PSP is not affected by light
    •  

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