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RADT465 IMAGE PROD.
ARRT registry review covering image production content area
Question | Answer |
---|---|
The tonal value of a histogram? | Whites are to the left and blacks are to the right. |
Changes in window width affect change in the number of ___ | Gray shades |
Changes in window level affects change in the image ___ | Brightness |
What is an X-ray production when a high-speed electron passes near a tungsten atom, is attracted, slows down and give up part of its energy? | Bremsstrahlung radiation |
Which X-ray production that comprises 70% to 90% of the x-ray beam | Bremsstrahlung radiation |
A high speed electron encounters a tungsten atom within the anode and ejects a shell electron leaving a vacancy in that shell. An electron from other shell moves to fill the vacancy and eject ___ radiation | Characteristic |
The x-ray beam that emerges from the x-ray tube focal spot before it strikes anything? | The primary beam |
X-ray photons emerging from the part that help contribute to forming the image? | The remnant or exit beam |
What is attenuation? | The gradual decrease in exposure rate as radiation passes through tissues |
What interaction occurs when a relative low-energy x-ray photon uses all its energy to eject an inner shell electron and leaving an orbital vacancy? | Photoelectric effect |
What kind of interaction that contributes significantly to patient dose? | Photoelectric effect |
What interaction occurs when a fairly high-energy x-ray photon ejects an outer shell electron and produce scatter radiation? | Compton scatter |
Other names for coherent scatter? | Classical, unmodified, or Rayleigh scatter |
What is the only interaction between x-ray photons and matter in which no ionization occurs? | Coherent scatter |
What interaction occurs when a very low-energy x-ray photon interacts with an atom of matter and excites it; as the atom re turns to its normal state, it releases an identified x-ray photon? | Compton scatter |
Electrical current flowing through a conductor in only one direction and with constant magnitude is called? | Direct current |
Which current has the amplitude and polarity of the current vary periodically with time? | Alternating current |
In the United States, AC is generated at ___ | 60Hz |
What is AEC? | Is the device that measures the quantity of radiation that reaches the image receptor. It automatically terminates the exposure when the IR has received the required radiation intensity. |
How many diodes a full-wave-rectified x-ray imaging systems contain? | 4 |
Voltage ripple | Single-phase power has 100% voltage ripple Three-phase, six-pulse power has 14% ripple Three-phase, 12-pulse power has 4% ripple High frequency generators have 1% ripple |
How to read the radiographic rating chart? | For a given mA, any combination of kVp and time that lies below and to the left the mA curve is safe. Any combination of kVp and time that lies above the curve is unsafe |
What is the cooling chart used for? | The anode cooling chart is used to determine the length of time required for complete cooling after any level of heat input. |
What kind of radiation is produce if an x-ray tube potential of less than 69kVp is used? | Bremsstrahlung. |
What kind of x-rays has a range of energies and forms a continuous emission spectrum? | Bremsstrahlung |
What kind of x-ray has precisely fixed (discrete) energies and forms a discrete emission spectrum? | Characteristic |
What is the effect of added filtration? | The result of added filtration is an increase in the average energy of the x-ray beam with an accompany reduction in x-ray quantity. |
The thickness of metal filters of an x-ray imaging system? | 1 to 5mm of Al |
A transformer will operate only with a/an___ | Changing electric current/ Alternating current (AC) |
Faraday’s law? | Electromagnetic induction: An electric current is induced in a circuit if some part of that circuit is in a changing magnetic field. |
Three steps of an acceptable QC program? | Acceptance testing, routine performance monitoring, and maintenance |
Three tools are used for measurement of focal spot size? | The pinhole camera, the star pattern, and the slit camera |
Contrast resolution? | refers to the ability of the digital system to display subtle changes in the shade of gray. |
Spatial resolution? | the ability of the imaging system to demonstrate small details of an object |
What is Look-Up-Table? | A LUT is a table that maps the imaging gray-scale values into some visible output intensity on a monitor or film. |
Automatic rescaling | Means that images are produced with uniform brightness and contrast, regardless of the amount of exposure used to acquire the image. |
Edge enhancement | Occurs when fewer pixels in the neighborhood are included in the signal average. |
Smoothing | Occurs by averaging each pixels’s frequency with surrounding pixel values to remove high-frequency noise. The result is a reduction of noise and contrast. |
Scintillator material? | Unstructured phosphor Gadolinium oxysulfide Gd2O2S2 and structured phosphor cesium iodide CsI. |
Lenses and fiber optics | Are used to focus light onto the CCD chip |
Image stitching | When anatomy or the area of interest is too large to fit on one cassette, multiple images can be stitched together using specialized software programs. |
Exposure indicators | The exposure index refers to the amount of exposure received by the IR, not by the patient. |
Teleradiology | The process of moving image via telephone lines to and from remote location |
Indirect capture digital radiography devices | Absorb X-rays and convert them into light. The light is then collected by an area-CCD, CMOS, or TFT array and then converted into an electrical signal that is sent to the computer for processing and viewing. |
Direct capture digital radiography devices | Convert the incident X-ray energy directly into an electrical signal, typically using a photoconductor as the x-ray absorber, and send the electrical signal to a TFT and then to an ADC. |
In PSP system, which layer traps electrons during exposure? | Phosphor layer/ Active layer |
What is the phosphor layer made of? | Phosphors from the barium fluorohalide family (barium fluorohalide, chlorohalide, or bromohalide crystals) |
In PSP system, how the signal is acquired and formed the image. | By a laser reader |
Advantages of CCD system? | CCDs are relatively inexpensive compared to TFT FPD system and much more simple. They are modular, making them easy to repair, replace, and upgrade. |
What is a semiconductor? | A semiconductor is a solid chemical element or compound that conducts electricity under some conditions but not others, making it good medium for the control of electrical current. |