Lmrt state review – Flashcards
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indicator number
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how much radiation was absorbed into the phosphors
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image stitching
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stitching together multiple images - useful for scoliosis studies of the spine, long bone studies or angiographic imaging of peripheral vasculature. - to view as a single image.
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image annotation
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allow the technologist to inset preset text or manual text on the image
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contrast resolution (digital)
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Ability to distinguish anatomic structures having similar subject contrast
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spatial resolution
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Refers to the amount of detail present in any image.Phosphor layer thickness and pixel size determines resolution in CR.
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pixel
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A single square within a matrix
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matrix
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a series of very small boxes that form a digital image
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direct conversion
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one step process in DR where flat panel detectors convert the x-ray energy directly to an electric signal using an amorphous selenium detector for immediate viewing
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charged coupled device
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component which light enters and is converted into video or electronic signal
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thin film transistor
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used to read charges collected during an exposure
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photodiode
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A silicon solid state device sensitive to light. Converts light into an electrical signal.
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scintillator
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Amorphous silicon requires a _____ such as cesium iodide or a rare earth intensifying screen composed of gadolinum and lanthanum with oxysulfides. This also converts x-rays to visible light.
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flat panel detector
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a type of digital detector employing amorphous silicon or selenium detector material, bonded with thin-film transistor technology for digital image creation and amplification
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density
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It is the degree of blackening of a radiograph resulting from radiation exposure and processing and one of the two photographic properties that comprise visibility of detail.
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automatic exposure controll
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a device that measures the quantity of radiation that reaches the image receptor and automatically terminates the exposure when the image receptor has received the required radiation intensity
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high frequency generator
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, What uses AC and DC power converters to change the incoming line from 60Hz to 6000Hz?
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three phase generator
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single phase generator
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produce a pulsating current that alternates from positive to negative and are power by a single source of ac
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diode
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A device that permits current to flow through it in only one direction
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rectification
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The process of converting AC to DC.
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filament circuit
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low-voltage circuit; uses 3-5 volts, regulates the flow of electrical current to the filament of the x-ray tube; controlled by mA settings
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high voltage circuit
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Purpose is to provide high electrical potential needed to accelerate electrons from cathode to the anode. Controlled by kVp.
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autotransformer
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Provides a variable yet predetermined voltage to the high-voltage step-up transformer. It acts as the kilovoltage selector.
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exposure switch
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closes the circuit and allows current to flow though primary side of step up transformer
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recorded detail
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Sharpness of the structural edges of the radiographic image. Describes the degree of geometric sharpness or accuracy of the structural lines recorded in the image.
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exposure time
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sid
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OID
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quantom mottle
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refers to the random nature by which x-rays interact with IR, under the control of radiographer and is principal contributor to radiographic noise (the use of high mAs, low kVp settings and slower IR's reduces ____)
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control consol
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The unit inside the control booth, where the operator sets all of the exposure techniques, such as: kilovolts peak, milliampheres, and exposure time.
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contrast
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shades of gray on an image
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x ray generator
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heat units
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The formula, mA x kVp x time, is used to determine what
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the maximum heat capacity of the anode of the x-ray is rated in terms of:
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heat units
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back up timer
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what is set in case of failure in AEC
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phototimer
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umbra
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actual anatomical area on a film
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penumbra
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The blurred/ indistinct area that surrounds an image
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prime factors
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What is the term for the three principal factors that affect xray emission that are under direct control of radiographer?
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prime factors
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kvp ma time SID
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anode heel effect
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It alters the intensity of radiation and therefore the density between the anode and cathode ends of the x-ray tube. Due to the geometry of an angled anode target, the radiation intensity is greater on the cathode side.
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thermionic emission
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The process of "boiling off" of electrons from the filament coils
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focusing cup
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small oval depression in the cathode assembly, the negative charge of the focusing cup helps direct electrons toward the anode in a straighter less divergent path.
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bremsstrahlung
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X-rays that are produced when a projectile electron is slowed by the electric field of a target atom nucleus
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15% rule
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used to maintain exposure to the image receptor and maintain radiographic film density. Increasing kvp 15% requires mas to decrease by 50%, decreasing kvp requires mas to increase x2.
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inverse square law
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Intensity of the x-ray beam is inversely proportional to the square of the distance between the source of x-rays and the image receptor.
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characteristic radiation
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Produced when a high-speed electron dislodges an inner-shell electron from a tungsten atom and causes ionization of that atom. Occurs only at 70 kVp and above.
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focal track
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The tungsten focal area all around the beveled edge of the rotating anode
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actual focal spot
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An area on the target surface that is struck by the electron stream
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effective focal spot
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The area of the focal spot that is projected out of the tube toward the object being radiographed is the:
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target angle
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The slant of the anode surface; between 7 and 17 degrees, with 12 degrees the most common; it affects the tube's heat capacity, the sharpness of the radiographic image, and the maximum size of the x-ray beam.
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potential difference
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In order to get electrons to flow, this is required.
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frequency
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How many waves can pass a given point per second, measured in Hertz (Hz)
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circuit
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electromagnetic conduction
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when the direction of current flow is reversed,creating alternating current
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primary radiation
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X-ray beam that leaves the tube and is attenuated, except by air. It's direction and location are predictable and controllable.
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tube port
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X-rays exit the tube housing through an opening called the
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velocity
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wavelength times frequency
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atomic number
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A unique number identifying the number of protons in the nucleus of an atom. This number identifyies the atom.
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atom
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Basic unit of matter; made of three sub-atomic particles (neutrons, protons, and electrons)
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matter
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Anything that has mass and takes up space
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molecule
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A particle made of two or more atoms bonded together.
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crest
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Highest point of a wave
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amplitude
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coolidge tube
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hot cathode x-ray tube; vacuum tube that allowed x-ray intensity and energy to be selected separately and with great accuracy
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crooks tube
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What type of tube was used when x-rays were first discovered?
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electric energy
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Energy of electric charges.
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thermal energy
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Energy from heat
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potential energy
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"stored energy"
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kinetic energy
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Energy of motion
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direct current
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Current that flows through a conductor in one direction only.
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alternating current
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Current that flows through a conductor in two directions that are periodically altered.
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resistor
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A material or device of a circuit that henders or opposes the flow of electricity
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asrt
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The curriculum being taught in your radiography program is based on the national radiography curriculum written by which professional organization?
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asrt
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American Society of Radiologic Technologists
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arrt
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American Registry of Radiologic Technologists
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arrt
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Give the registry exam and your credentials upon passing the exam are: ?
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jrcert
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Joint Review Committee on Education in Radiologic Technology - educational standards and accreditation
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ionization
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process in which an atom gains or loses an electron
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rectification
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The process by which alternating current is changed to pulsating direct current
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central ray
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line that is perpendicular to the long axis of the x-ray tube and is in the center of the x-ray beam. X-Ray beam an imaginary line in center of x-ray beam and peerpendicular to long axis of the x-ray tube.
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Image receptor
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______ _______ - medium used to capture the image for recording, such as x-ray film or a digital imaging plate. An interpretation device that intercepts the x-ray photons that are able to exit the patient.
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remnant radiation
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All radiation exiting the patient during exposure and ultimately striking the receptor.
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scatter radiation
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A form of secondary radiation that occurs when an x-ray beam has been deflected from its path by interaction with matter
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wilhem conrad roentgen
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Discovered x-rays on nov 8, 1895.
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cathode
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a negatively charged electrode that is the source of electrons in an electrical device
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anode
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a positively charged electrode by which electrons leave an electrical device
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neclear energy
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chemical energy
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Energy available in molecules for release in a chemical reaction; a form of potential energy
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bucky
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step up transformer
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step down transformer
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