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An image intensifiers photocathode causes ___ to be given off in direct proportion to the intensity of the fluorescent light
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What fluoroscopic television system device decodes the video signal into a visible image?
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Fluoro
| Question | Answer |
|---|---|
| An image intensifiers photocathode causes ___ to be given off in direct proportion to the intensity of the fluorescent light | Electrons |
| What fluoroscopic television system device decodes the video signal into a visible image? | Television Monitor |
| Which of the following materials are used in the construction of a fluoroscopic tabletop? | Aluminum Bakelite Carbon fiber |
| Shape distortion is caused primarily by | Geometric factors in the shape of the image intensification tube |
| If the entrance skin dose is measured from the surface of the tabletop, the x-ray source is located | Under the table |
| The mottle level of an image can be adjusted by | 1. changing mA 2. changing kVp 3. changing the exposure factors 4. increasing the number of available x-ray photons |
| During a fluoroscopic exam, the main source of scattered radiation is produced from | The Patient |
| Excessive lighting in the fluoroscopy room: | May result in increasing the technical operating factors |
| For fluoroscopic installations, the primary barrier is considered to be the | Image intensifier assembly |
| The input phosphor of an image intensification tube | 1. absorbs x-rays 2. is a layer of fluorescent material |
| Images produced with photo spot film cameras ___ spot films taken with conventional cassettes | require about 1/2 to 1/3 the dose of |
| When the magnification mode is used, an increase in image intensifier resolution will increase from | 4 lp/mm to about 6 lp/mm |
| Remnant, exit, or imaging forming radiation consists of | Non-interacting photons Small-angle scattered photons |
| The overall resolution of the imaging system is expressed in terms of its | modulation transfer function (MTF) |
| Size distortion is primarily caused by | Object-to-image distance (OID) |
| Why is it important to coordinate the video signal between the TV camera and the TV monitor | To avoid unnecessary flicker in the television picture |
| The ability of an imaging system to differentiate small objects that are closely spaced as separate objects is referred to as: | Resolution |
| The exposure rate at the tabletop may not exceed five rads per minute except | 1. when using the ABC on large patients 2. during magnification mode 3. where higher exposure rates are allowed |
| How will the fluoroscopic image brightness be affected as the fluoroscopic field of view (FOV) is reduced with tighter collimation? | Image brightness will not change |
| When the fluoroscopy beam-on time has exceeded a predetermined limit, the cumulative manual-reset timer must either | 1.Produce an audible signal 2.Interrupt the x-ray beam |
| The greatest distribution of fluoroscopic examinations (approximately 53%) are performed on which body part? | GI Tract |
| The Input phosphor of an image intensification tube | 1. absorbs x-rays 2. is a layer of fluorescent material |
| By selecting ___ one can achieve obtain maximum differential absorption of the tissues in order to produce a high-quality fluoroscopic image | Peak kilovolts |
| The “visibility” of mottle in the virtual image is determined by the ___ of the system in use: | a. Resolution b. Sensitivity c. Contrast level |
| What fluoroscopic television system device decodes the video signal into a visible image | Television Monitor |
| Which device serves to coordinate the events to retrace the exact image on the television monitor as viewed on the output phosphor via the vidicon camera | Camera Control Unit |
| The television monitor used for viewing the fluoroscopic image contains | 1. Cathode Ray Tube (CRT) 2. Control for regulating contrast 3. Control for regulating brightness |
| Fluoroscopic protective curtains must be made of at least ___ equivalent material. | 0.25mm lb |
| Shape Distortion is caused primarily by: | Geometric factors in the shape of the image intensification tube |
| The statistical image quality of a fluoroscopic imaging system is primarily determined by the number of: | X-ray photons |
| Suitable gonad shields must be used: | When shielding of gonads does not interfere with the diagnosis |
| Which of the following are true concerning cine film? | The larger the film size the better the image quality |
| The photoconductive target in a television camera pick-up tube: | Allows a proportional electron charge to be generated at a particular position |
| The overall luminescence of the TV image may be properly adjusted by | 2. adjusting the brightness and contrast control button on the TV monitor |
| Where is the fluoroscopic grid located | Located between the patient and input layer of the image intensifier |
| One of the most important actions a fluoroscopist can take to avoid unnecessary radiation exposure to the patient is to use appropriate | Collimation |
| The increase in effective brightness due to the size reduction of the output image size is referred to as | Minification Gain |
| In a TV camera, the proportional electron charge is converted into a proportional voltage which is sent to the | Camera control unit |
| The greatest limiting factor concerning resolution for fluoroscopic systems is the | Video Monitor |
| Since the Bucky tray cover is directly in line with the fluoroscopists gonads, the opening must be automatically covered with ___ equivalent material | 0.25mm/pb eq |
| What percentage of incident photons will emerge unaffected by the patients tissues? | 5% |
| The primary purpose of protective drapes or sliding panels is to: | 1. Reduce scatter to the operator 2. Reduce radiation coming primarily from the patient |
| The components of the closed-circuit television system are | 1. vidicon camera 2. camera control unit 3. television monitor |
| The component in an image intensifier that regulates or changes the amount of magnification in the vertual image is the | Electrostatic Lenses |
| How does the focal spot size of fluoroscopic x-ray tube differ from a radiographic x-ray tube? | Often designed with a smaller focal spot |
| The best recorded resolution is obtained with use of: | Spot films using conventional cassettes |
| The total filtration used in fluoroscopic x-ray tubes operating above 125 kVp must be a least: | 3.0 mm Al equivalent |
| Fluoroscopy is defined as a radiological examination utilizing ___ for observation of the transient mage | Fluoroescence |
| The optimum source-to-skin distance is ___ for stationary fluoroscopic equipment and ___ for mobile fluoroscopy equipment | 45cm Fixed 30cm Mobile |
| When referring to a lens system, a higher ‘f-number’ will result in less ___ being available to form an image on cine film | Light |
| Two minutes of actual fluoroscopic exposure time during a UGI Fluoro study could deliver a skin entrance exposure to the patient ranging from: | 5 to 15rads |
| Image intensification refers to | The brightening of the fluoroscopy image using the image intensifier |
| The input screen is coated with a Phosphor that converts x-ray photons to | Light photons |
| The light from the input screen strikes | The photocathode |
| There photocathode emits what? | Photo electrons |
| What voltage is applied to the electrostatic lenses | 25 to 30 KV |
| The output screen converts photoelectrons into | Light |
| Minification gain formula | Diameter of input screen 2/by diameter of output screen 2 |
| Brightness gain formula | Minification gain X flux gain |
| The output phosphor is brighter at it’s ___ and it’s resolution is better at it’s ___: | center, center |
| Remnant radiation interacts with what part of the image intensifier | Input Phosphor |
| Pincushion distortion will be minimized with a ___ inch image intensifier | 6 inch II, generally in mag mode |
| The purpose of rotating the target disc in a fluroscopic x-ray tube is to | Distribute intense heat efficiently over a large area |
| When an image intensifier is operating in a magnification mode, the: | The field of view is decreased |
| When quality factor called spatial frequency is increased, so does the | Number of line pairs/mm |
| Image “lag” is generally considered to be a disadvantage, however, a latent effect of lag when using a vidicon TV camera is: | 1 Minimizes the effects of quantum mottle 2 Averages out the statistical fluctuations |
| When switching from a 6-inch magnification mode to a 9-inch mode, how will the patient’s radiation dose be altered | Decreased by 2.25 times |
| Which of the following terms refers to the size ratio between the input and output phosphor screens | Minification gain |
| The brightness gain achieved by the efficiency of an output phosphor to convert electrons to light photons is referred to as: | Flux Gain |
| Fluoroscopic magnification is made possible by varying the voltage applied to the | Electrostatic Lenses |
| The ability of the image intensifier to increase the overall illumination level of the image is called its | Brightness gain |
| The key advantage of a dual magnification mode image intensifier versus a single mode unit is | Versatility |
| Useable light from the output phosphor of an intensifier tube can be reflected and projected toward a | 1. Cine camera 2. Photospot camera 3. Spot film camera |
| What function does the output phosphor serve in an image intensifier? | Convert the energy of electrons bombarding it into visible light |
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