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162 Cards in this Set
- Front
- Back
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What is a Crookes tube?
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cathode ray tube; forerunner for fluorescent lamp and neon sign
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What else did the Crookes tube produce but no one detected them?
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x-rays
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When were x-rays discovered? By whom?
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November 8, 1895 by Wilhelm Conrad Roentgen
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What caught Roentgen's attention across the room (not relate to his light experiment)?
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a plate coated with barium platinocyanide crystals began to glow
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What and why did Roentgen name this phenomenon?
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x-rays, x being the symbol for the unknown
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Wheen and where was the first medical use for x-rays?
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February 1896 at Dartmouth College on a youn boy's fractured wrist.
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What significance did H.C. Snook and William Coolidge play?
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Snook worked with alternating current generators and developed the interrupterless transformer. Coolidge designed the "hot cathode" to work with Snook's generator and was the prototype for the x-ray tubes of today.
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What contribution did Pupin make?
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Demonstrated the radiographic use of fluorescent screens called intensifying screens to expose to phographic plates
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What contribution did Thomas Edison make?
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invented first fluoroscope and discovered many of the fluorescent chemicals used today
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Why did Edison stop his work with x-rays?
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His assistant and friend, Clarence Dally, burned his arms on x-rays to the point of being amputated
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Who was recorded as the first recorded x-ray fatality in the US?
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Clarence Dally
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Who and what did George Eastman contribute?
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He was the founder of Eastman Kodak Company. He developed a cellulose nitrate, a base for emulsions for photographic film.
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What was occurring in doctors and patients in the 20th century?
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skin burns, hair loss and anemia
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what is anemia?
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A decrease of hemoglobin in the blood level below normal
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Who was called an "x-ray technician?"
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physician assistants trained to develop and assist in x-ray examinations
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How were "techinicians" trained prior to WWII?
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on the job with minimal formal education
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Describe the path that x-rays take from exposure of the x-ray tube to the film.
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Pass from out of the tube through the patient and table and onto the film
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What happens to the x-rays when they go through the patient?
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Some are absorbed by the patient's boy and some are not, resulting in a patter of varying intensity (densities) the exists on the film.
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What are they called if they do not contact the film?
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scatter radiation
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What is a latent image?
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an exposed radiographic film that has not been processed
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How do you make a latent image visible?
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a vacuum
source of electrons a target for the electrons high potential difference (voltage) between electron source and the target |
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What is the x-ray tube "glass envelope" make out of? Why? Why is the air removed?
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pyrex glass to withstand heat and so gas molecules will not interfere with the x-ray production
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What is the source of electrons and what is it made of?
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a wire filament made of tungsten
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How are "free electrons," called the space charge made?
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the tungsten is heated to separate electrons from the nucleus forming and "electron cloud"
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Where are x-rays generated?
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at the target, the other end of the tube when the free electrons hit it
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The filament or cathode end has a ______ charge?
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negative
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The target of anode end has a ______ charge
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positive
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How does the transformer cause an electron stream?
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the transformer connects the circuit during an exposure
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How many x-rays are made when the electrons hit the target?
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less than 1%
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Other than x-rays, what is made when the electrons hit the target?
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heat
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What does the anode do to cool down?
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rotates
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What is amplitude?
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the distance between the crest and valley of the wave
HEIGHT OF THE WAVE |
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What is wavelength?
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the distance from one crest to the other
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What is frequency?
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the number of times per second that a crest passes a given point
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The more energy the wave has, the _______ frequency and the ______ its wavelength.
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greater; shorter
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In radiology, wavelength is often used to describe?
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the energy of the x-ray beam
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What has sufficient energy to remove and electron from its atomic orbit?
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ionizing radiation, in wich the x-rays are one type
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What is a photon?
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a miniature "bullet" of energy
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What arethe characteristics of x-rays?
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travel in straight lines, have an effect on photographic emulsions, have a biologic effect on living organisms, can not be detected by human senses, can penetrate matter that is opaque to light, cause certain crystals to fluoresce, cannot be refracted by a lens
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What does opaque mean?
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a substance that will not allow the passage of light
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X-rays that have passed through air, oil, water, muscle , or bone and expose the film are called what?
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remnant radiation
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What pattern is recorded on the film?
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the patter of intensity that reflects the penetration characteristics of the subject
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How many x-rays show as remnant exiting the air?
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5
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How many x-rays show as remnant exiting oil/fat?
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4
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How many x-rays show as remnant exiting water or muscle?
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2 or 3
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How many x-rays show as remnant exiting bone?
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1
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What do crystals in intensifying screens do?
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The crystals convert x-rays into visible film that can be viewed directly as in fluroscopy or recorded film
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Of what benefit are intensifying screens?
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they greatly reduce the quantity of radiation needed thereby decreasing the patient's dose
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How long do x-rays stay in the air (space)?
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til they are absorbed by matter
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Define radiation field.
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the entire field (area) that the x-rays are covering
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Define central ray.
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the imaginary cen of the beam that is perpendicular to the table
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What is beam divergence?
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The point of origin of the x-rays is very small and widens as they emerge.
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The beam is restricted by the ___ and a ___ that is controlled by the radiographer.
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port and collimator
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Defind secondary or scattered radiation.
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partially absorbed within a substance, has less energy and is difficult to control
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What does dual focus mean?
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x-ray tubes contain two filaments, one large and one small
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What is the purpose of the focusing cup?
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it directs electrons toward the target
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THe small filament and small focal spot provide what?
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smal focus with small-finer image detail (lower mA)
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The large filament and large focal spot provide what?
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large focus with more electrons, more heat absorption, butt less image and detail (higher mA)
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What four functions does the x-ray tube housing provide?
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shielding from radiation not part of the useful beam.
protects and insulates the tube. provides a base for manipulation of attachments. and the means to control the size and shape of the x-ray beam. |
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The x-ray tube can either ____ mounted or ____ mounted.
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ceiling or floor
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Describe the tube motion for longtitudinal.
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along the long axis of the table
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Describe the tube motion for vertical.
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up or down
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Describe the tube motions for roll.
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angles the tube side to side. table or wall
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Describe the tube motions for rotation.
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turns the tube stand on its axis
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what does a detent do?
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stops (locks) the moving part (tube) in specific locations
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What function does the centering line perform?
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aligns the cassette tray tothe tube
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What benefit is a vertival table motion (motorized) to patients and the radiographer?
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allows lowering the table so the patient can sit easily and rising to a comfortable work height for the radiographer. match stretcher height for patient transfers
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What benefits are associated with a tilting table?
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patients' positions from horizontal to vertical or angle in between without moving the patient.
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What is the Tredelenburg position?
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patient is placed to where the head is 15 degrees lower than the feet
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What should you check before tilting the patient in any position and the table?
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the footboard or shoulder guards for the patients' safety and objects , like footstools or chairs are out from under the table.
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What does a floating table top accomplish?
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allows the patient to move independantly of the remainder of the table for ease in aligning the patient part to the tube and film
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Define the use of a bucky.
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holds the cassette tray that holds the film and can be moved the length of the base of the table and locked in postition
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Define the use of a grid.
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a grid is between the table top and the film attached to the top of the bucky device. Made of tissue-thin strips of lead, with a radiolucent interspacing material. Protects the film from secondary radiation (fog) from the patient.
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Grids can be ___ to blur its own image so it's not visible; ____that don't move or incorporated (built in) a special cassette called a ____.
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moving, stationary, grid-cassettes.
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Are grid-cassettes moving or stationary?
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stationary
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When do you use a grid?
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when a body part is over 10-12 cm thick
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List the controls on a typical control console.
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off/on, mA, kVp, timer, mAs, bucky switch, automatic exposure controls, meters or digital displays, exposure prep and switch
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What does exposure time measure and for how long?
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measures how long the exposure with last and is measured in seconds, fractions of seconds, and milliseconds.
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What determines the total quantity of radiation?
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time and milliamperage
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What was the fluoroscope designed for?
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a direct viewing of the x-ray image and permits direct viewing in motion
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What does R/F mean?
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radiographic/ fluoroscopic unit
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What is the purpose and function of the image intensifier?
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to reduce radiation and brightens and enhances the image
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What sounds after 5 minutes on an R/F unit?
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an alarm alerting the radiologist that the fuoroscopic init has been in use for 5 minutes
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Explain how with just time, what the effects on a radiograph and the patients does would be if they are increased and decreased?
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more time=increased exposure=darker film=greater dosage.
less time=decreased exposure=lighter film=a lesser dose. |
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What does mA determine?
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The rate at which x-rays are produced. An indication of the number of x-ray photons produced per second.
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Specific mA stations control what?
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the large or small filament
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mA settings of 150 or less control which filament and focal spot?
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small
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mA settings of 200 or more control wich filament and focal spot?
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large
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Define kVp.
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measurement of the potential difference across the tube to determine the speed of electrons and determines the kinetic energy each electron has when it collides with the target and thus the amount of energy in the x-ray beam, expressed by the wavelength of the photons.
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An increase in kVp has____ wavelengths and produces a ____ film.
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shorter, darker
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kVp has ___ wavelengths and produces a ____ film.
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longer. lighter
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Changing the kVp will alter the ___ on the film.
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contrast
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Typical kVp settings for small body parts range from ____ to ______; and for the spine from _____ to ______ and for the chest or barium from _____.
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50 to 60; 75 to 100; 100+
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Define SID
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the source of image distance between the tube target and the film
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How is SID a factor in exposure?
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the intensity of the beam decreases between the tuve target and the film.
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What happens due to divergence to the size of the exposed area when the SID is decreased?
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The beam area gets smaller and there are more photons in any given area.
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What happens due to divergence to the size of the exposed area when the SID is increased?
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The beam area gets larger and there are less photons in any given area.
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The inverse square law states:
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The intensity of the radiation is inversely proportional to the square of the distance
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Define the use of technique charts.
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provides a list of mAs and kVp settings and SID for various body parts
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What is inside the light-tight, rigid cassettes?
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the film and two intensifying screens on either side of the film.
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Most departments have what two types of screens?
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"fast" with large crystals for routine imaging
"slow" with small crystals for small detail imaging. |
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Why is a small portion of the cassette not covered by the screens?
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It is reserved for the photographic imprint of the patient's identification
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Can a green sensitive film be used on screens that emit blue light?
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no
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Is there a wrong side to single-emulsion film and only one intensifying screen?
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yes. they ahe to be together touching the cassette
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Why must your hands be dry and clean when handling film?
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to prevent artifacts, fog, smudges and fingernail marks on the image
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What is a film bin?
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A storage unit located in the dark room that holds unexposed film
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What is a safe light?
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A light that emits just enough light ina different light spectrum that allows you to see in the darkroom
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What device allows cassettes to be passed to and from the darkroom without allowing light into the darkroom?
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a pass box or rolling circular darkroom door
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What is computed radiography?
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an imaging system that does not use film, but an IR inside a special cassette
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What four features make up the four elements of radiographic quality?
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density, contrast, resolution, distortion
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Define radiographic density?
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the overall blackness of the image
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What is the primary control factor for density?
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mAs
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Define radiographic contrast.
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The differencee in the densities of adjacent structures on the film.
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What is the primary control factor of contrast?
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kVp
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What appearance is seen on a high contrast image?
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black and white
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What appearance is seen on a low contrast image?
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structures blending and over lapping. black-grayish, white
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If you want to produce a high contrast the kVp is____?
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decreased
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IF you want to produce low contrast, the kVp is ___?
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increased
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Define radiographic definition.
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refers to the size and shape of the structures represented on the image when compared to the object
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Size distortion is always in the form of?
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magnification
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What factors affect definition?
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SID, OID, size of intensifying screen crystals, thickness of phosphor layer, motion
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What two factors cause magnification?
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SID OID
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In relation to just reducing magnification, we would want to use a (longer or shorter) SID and (increase or decrease) the OID?
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longer, decrease
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What is abbreviated R?
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Roentgen, a measurement of radiation intensity in air.
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RAD stands for and is used for?
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Radiation absorbed dose. measures therapeutic radiation doeses and specific tissue doeses received in diagnostic exams
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REM stands for?
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Roentgen equivalent in man
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What four characteristics of a cell make them sensitive to radiation?
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age- younger cells more sensitive
differentiation- simple cells are more sensitive metabolic- cells that use energy rapidly are more sensitive mitotic rate- rate of cell division determines sensitivity |
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Based on the laws of Bergonie and Tribondeau, what tissues are more sensitive?
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Embryos, fetuses, infants, children, adolescents
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Long term effects are those....?
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referred toas latent effects, may not be apparent for as long as 20 years.
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What is the difference between Somatic and Genetic effects?
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Somatic- affect the irradiated individual
Genetic-effect the offspring o the irradiated individual |
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What is the whole body dose fatal for 50% of the population within 30 days?
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300 rad for humans, this is referred to as LD (lethal dose)
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As a radiographer, which effect, long term or short term, must you be aware of and why?
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primarily longer term because effects are random with repeated small doses
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Concerning genetic effects, why must radiographers be concerned about radiation exposure to the ovaries in females and testes in males?
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females- no new eggs are produced therefore doeses are cumulative to the eggs.
males- doses could damage stem cells that produce sperm causing mutations |
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Regarding radiation safety, you have to huard radiation exposure to whom?
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your patients, coworkers, yourself, and a parent if your patient is a child.
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Why are radiographers prohibited from activities resultingin direct primary beam exposure?
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because they are "occupationally exposed individuals"
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What type of exams does the radiographer's exposure increase?
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fluoroscopic and mobile equipment
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what are the 3 principle protection methods?
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time distance and shielding
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Primarily these 3 principle protection methods are to protect whom?
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x-ray equipment operators
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Describe how time offers radiation protection.
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time-directionally proportional to exposure therefore decreased time- decreased exposure
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Describe how distance offers radiation protection.
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increasing your distance from the exposure source decreases your exposure to the square of distance
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Describe how shielding offers radiation protection.
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placing your body behind a protectie barrier will greatly reduce or eliminate exposure to radiation
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Who is responsible for all persons before a radiation exposure is made?
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you, the radiographer
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What device is used to monitor radiation exposure to personnel?
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dosimeters
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What is the most precise device used today?
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OSL's optically stimulated luminescence
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What is the purpose of the control badge?
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It measures radiation exposure to the entire batch while in transit. This amount is subtracted from the badges for an accurate reading.
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Who is responsible for your exposure history when you leave employment?
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The employer is responsible for monitoring and maintaining the records and providing them. However, you are responsible to ask for it.
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What is MPD and what is it used for?
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Maximum permissible dose for occupationally exposed personnel is 5 rem per year
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The ALARA acronym stands for?
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As Low As Reasonably Achievable
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Why is this philosophy important?
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That radiographers not become complacent about radiation exposure
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when is gonad shielding required?
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When gonads are in or within 5cm of the primary radiation field and only when the shild will not interfere with the exam
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What are the two main types of gonad shields?
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shadow and contact
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In general, it is possible for what to occur to a developing embryo or fetus if exposed to radiation?
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spontaneous abortion congenital defects, increases risk of malignant disease and an increase of genetic abnormalities
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What is MPD in rem and mrem for a pregnant worker over the 9 month term?
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.5 rem or .0005 mrem
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Regarding the general population, which type of exams would be a cause for concern?
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Exams directly on the abdomen, pelvis, lumbar spine, fluoroscopic exams or CT scans
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How do we alert potential mothers?
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post signs in common languages and ask them if they are expecting
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When is pregnancy not considered?
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in an emergency/ trauma situation
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What is the Ten Day Rule?
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a woman is least likely to be pregnant in the 1st ten days since the beginning of her menstrual cycle
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What is the focus of your studies now and when you begin your practice
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to use x-rays safely to aid in the diagnosis of illness and injury
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What is the crisis intervention approach?
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The patient or client seeks help only when unable to manage alone
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What is the health maintenance or preventitive health system approach?
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promotes well-being and avoiding the need for medical intervention. Good nutrition, exercise, promotes self-care that avoids bad habits
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What is Medicare?
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federal medical insurance program for those over 65
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What is Medicaid?
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federal program for the medically indigent.
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