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RADT 312 Units 1 & 2
Fluoroscopy, Mobile Radiography
| Question | Answer |
|---|---|
| Who invented Fluoroscopy? | Thomas Edison |
| When was Fluoroscopy invented? | 1896 |
| Who invented the Image Intensifier (II) tube? | John Coltman |
| When was the Image Intensifier (II) tube invented? | 1940's |
| What are static or still images called? | Spot views |
| T/F: The exposure rate in Fluoroscopy in less than overhead radiography, but the total accumulated exposure to the patient is higher | True |
| What is the exposure rate of conventional Fluoroscopy? | 1-5 |
| Due to low exposure rate, fluoroscopic images are statistically inferior to overhead images because of: | more noise |
| ABC stands for | Automatic Brightness Control |
| What does ABC change or alter due to attenuation? | kVp and mA |
| What diameters is the input phosphor in the II available in? | 6. 9. 12. 16 inches |
| What diameter is the output phosphor in the II? | 1-3 inches |
| When you increase the physical diameter of the input phosphor, does this increase or decrease image resolution? | Increase |
| What is the input phosphor made of? | Cesium Iodide |
| What does the input phosphor do? | Absorb x-rays and re-emit the energy as light |
| What does the photocathode do? | Absorb light from the input phosphor and emits electrons |
| In the input phosphor, how many light photons are produced from each x-ray photon? | Thousands |
| Are Electrostatic Lenses positively or negatively charged? | Negatively |
| What do the electrostatic lenses do? | Focus the electron beam onto the output phosphor |
| Does concentrating electrons increase or decrease output intensity? | Increase |
| What is it called when the concentration of electrons increase output intensity? | Minification |
| What is the output phosphor made of? | Zinc cadmium |
| What happens after the light is picked up from the output phosphor? | The light image is read by a CCD |
| What is Flux Gain | (“Flow gain”), the ratio of increase in kinetic energy from acceleration of the electrons from the cathode end to the anode end of the tube |
| Overall brightness gain is a result of: | Minification Gain x Flux Gain |
| Field of View in Fluoroscopy pertains to: | The active diameter of the input phosphor |
| Does Magnification Mode increase or decrease FOV? | Reduces |
| Does the focal point move closer to the input phosphor or further away when in magnification mode. | Closer |
| Does Magnification mode improve spatial resolution? | Yes |
| Does Magnification mode improve sharpness? | Yes |
| What does ABC do? | increases the mA to compensate for the loss of minification gain |
| What does AGC stand for? | Automatic Gain Control |
| What does ABS stand for? | Automatic Brightness Stabilization |
| With AGC, what is amplified as needed by circuits due to the compensation of increasing part thickness? | Electronic signal |
| With ABS (more common), what is adjusted as needed to the compensate for increasing part thickness? | Radiographic technique factors |
| What type of ABS circuit has a set kVp but varying mA? | Variable mA, preset kVp |
| What type of ABS circuit has a varying mA and varies the kVp once the upper boundary of mA has been met? | Variable mA with kVp following |
| What type of ABS circuit is the mA set by the operator but the kVp varies? | Variable kVp with selected mA |
| What type of ABS circuit do both the mA and kVp vary as needed? | Variable kVp, Variable mA |
| Patient exposure regulations require that an ABS system must keep patient exposure to: | < 10 R/min |
| How does brightness vary with mA? | Directly |
| How does brightness vary with kVp? | To the 5th power (A 10% increase in kVp brightens the image by more than 50%) |
| True or False: No form of electronic intensification can improve the image above the statistical level of the absorbed x-ray photons. | True |
| What are small, momentary defects in the distribution of brightness (“twinkling”) in a dynamic image (similar to mottle) | Scintillation |
| What is the best solution for Scintillation? | Raise mA |
| Contrast deteriorates with aging of the intensifier – deterioration can be as high as what % per year | 10% |
| What distortion is a slight magnification and increased blur around the periphery of the image? | Pincushion Distortion |
| What causes Pincushion Distortion? | By projecting the image from a curved input phosphor to a flat output phosphor |
| True or False: Operation in magnification mode yields a sharper image because the most extreme curvature of the input phosphor at the periphery is eliminated | True |
| What distortion has Magnification and blur in an S pattern? | S - Distortion |
| What distortion has scattered random light from the output phosphor? | Veiling Glare |
| What is it called when there is loss of brightness toward the periphery of the image? | Vignetting |
| Which type of table significantly reduces skin entrance exposure to the patient? | Carbon Fiber |
| Proper collimation can help reduce what in intensified fluoroscopy? | Noise |
| On a mobile C-arm fluoroscopy unit, which lock would be used to re-center the image intensifier more toward the patient's head without changing the type of projection (PA): | Longitudinal lock |
| What is a common term or name for the C-arm Longitudinal lock | Wig-Wag |
| What does it mean when you Rainbow the c-arm? | The II is under the table (patient) and the x-ray tube is "on top" |
| With the c-arm in a lateral position, is it safer to be on the II side or the x-ray tube side for limiting occupational dose? | II side |
| When performing mobile radiography to demonstrate joint spaces, it is most important to keep the central ray perpendicular to the: | Anatomy |
| For mobile radiography, what should a radiographer use for the most accurate technique? | Technique charts |
| How long do the automatic timers take to go off during fluoroscopy / c-arm procedures? | 5 minutes |
| True/False: Pulse mode helps reduce patient dose. | True |
| What is Ceiszynski's Law of Isometry | Split the difference between two angles to minimize distortion |
| The input phosphor side of an image intensifying tube, comprises the ________ side of the tube. | Negative |
| The output phosphor side of an image intensifying tube, comprises the ________ side of the tube. | Positive |
| What views are preferred for Air-Fluid Levels? | Upright and Decubitus |
| Which sequence best defines the actions occurring in the process of image intensification from input phosphor to the CCD of the image intensifying tube? | X-ray -> Light -> Electrons -> Light |
| If a mobile device is missing a measuring tape, what can be used to measure for 72"? | Wingspan of a 6ft tall individual |
| If a mobile device is missing a measuring tape, what can be used to measure for 40"? | average person can use fingertip-to-opposite axilla |
| At what distance from the source of radiation is it considered safe? | 6 feet |
| When performing mobile radiography to demonstrate joint spaces, if you have to choose, it is most important to keep the central ray ________ to the anatomy | Perpendicular |
Created by:
rdwilliams
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