Chapter 15 Essentials Fluoroscopic Imaging
The original fluoroscopic image was very a. dim b. bright c. clear d. fuzzy
ANS: A A major problem with the original fluoroscopic image was that it was very dim and hard to see.
If a 30/23/15 cm image intensifier is operated in the 23-cm mode, the fluoroscopic image will be magnified by a factor of a. 1.3 b. 1.5 c. 1.7 d. 2
ANS: A Based on the formula, the MF = the full size of the input phosphor (30 cm)/the selected input phosphor size (23 cm).
An expression of the ability of an image intensifier tube to convert x-ray energy into light energy and increase the brightness of the image in the process is the a. brightness gain b. flux gain c. minification gain d. conversion factor
ANS: A Brightness gain is an expression of the ability of an image intensifier tube to convert x-ray energy into light energy and increase the brightness of the image in the process.
This allows the film to be divided into 2, 4, or more images. a. Cassette spot filming with masking shutters b. Film cameras for spot filming c. Videotape d. Flat panel detector
ANS: A Cassette spot filming with masking shutters can be set up to record two images per film (two on one), four on one, or more.
Fluoroscopic imaging systems operate at: ________ a. 2-5 mA b. 15-20 mA c. 200-500 mA d. Unlimited mA
ANS: A Fluoroscopic imaging systems operate at 2-5 mA.
The difference between geometric magnification and electronic magnification is a. geometric magnification is where the patient is placed closer to the x-ray tube to create a larger OID and electronic magnification involves the selection of a smaller field of view b. electronic magnification is where the patient is placed closer to the x-ray tube to create a larger OID and geometric magnification involves the selection of a smaller field of view c. there is no difference between geometric magnification and electronic magnification
ANS: A Geometric magnification is where the patient is placed closer to the x-ray tube to create a larger OID and electronic magnification involves the selection of a smaller field of view.
A fluoroscopic feature that automatically turns the x-ray beam on and off rapidly during operations is known as: a. Pulsed fluoroscopy b. Frame averaging c. Intermittent fluoroscopy d. Pulse rate
ANS: A Pulsed fluoroscopy is simply a design of the unit that rapidly turns the x-ray beam on and off during operation.
A face plate, signal plate, and target are all components of the a. anode of the camera tube b. charge coupled device (CCD) c. cathode of the camera tube d. x-ray tube
ANS: A The anode end of a camera tube includes a face plate, signal plate, and target.
The electrostatic focusing lenses have a ___________ charge. a. negative b. positive c. neutral d. changing
ANS: A The electrostatic focusing lenses have a negative charge.
The __________________________ absorbs x-rays and emits light. a. input phosphor b. output phosphor c. photocathode d. accelerating anode
ANS: A The input phosphor absorbs x-rays and emits light.
This part of the image intensifier is made of cesium iodide. a. Input phosphor. b. Output phosphor. c. Photocathode. d. Accelerating anode.
ANS: A The input phosphor is made of cesium iodide.
The formula to determine the amount of magnification created when in magnification mode, the formula is a. MF = full size input phosphor / selected input phosphor b. MF = full size input phosphor2 / selected input phosphor2 c. MF = selected input phosphor / full size input phosphor d. MF = selected input phosphor2 / full size input phosphor2
ANS: A The magnification factor during fluoroscopy = full size input phosphor / selected input phosphor.
Increasing the mA is the way to correct a fluoroscopic image that has a. noise b. pincushion appearance c. vignetting d. magnification
ANS: A When a fluoroscopic image has noise, or is noisy, the quantity of radiation (mA) must be increased because the issue is too few photons being used to create the image
Which of the following recording systems require the x-ray-beam to be in radiographic mode? a. Cassette spot filming. b. Film cameras for spot filming. c. Cine filming. d. Flat panel detector.
ANS: A When the spot-film exposure button is pressed, the cassette is moved into position between the patient and image intensifier and the machine shifts from fluoroscopic to radiographic mode and exposes the film.
What fluoroscopic feature allows the position of the collimator plates to be viewed on the monitor without exposing the patient to radiation? a. last image hold b. frame averaging c. digital subtraction d. electronic magnification
ANS: A With the newest units, lines will appear on the last image hold (LIH) displayed on the monitor, indicating the position of the collimator plates.
A typical high-resolution monitor has a. 825 line systems b. 1024 line systems c. 525 line systems d. 2034 line systems
ANS: B A typical high-resolution monitor has 1024 line systems.
The _____________ is a diode tube contained in a glass envelope to maintain a vacuum, and is connected to the output phosphor of the image intensifier by either a fiberoptic bundle or an optical lens system. a. television monitor b. Vidicon camera tube c. charge coupled device (CCD) d. liquid crystal display (LCD)
ANS: B A vidicon camera tube is a diode tube contained in a glass envelope to maintain a vacuum, and is connected to the output phosphor of the image intensifier by either a fiberoptic bundle or an optical lens system.
The CCDs electric charge from the capacitors is sent to the a. output phosphor b. television monitor c. x-ray tube d. image intensifier
ANS: B After being briefly stored in the capacitor, the charge travels by wire to the television monitor.
Early versions of digital fluoroscopy used the conventional fluoroscopic chain and added a. a different camera b. an analog-to-digital converter (ADC) c. videotape d. a digital-to-analog converter (DAC)
ANS: B Early digital fluoroscopy systems added an analog-to-digital converter between the camera and monitor.
This recording system uses 70-mm or 105-mm film. a. Cassette spot filming b. Film cameras for spot filming c. Videotape d. None of these
ANS: B Film cameras use either 105-mm "chip" film or 70-mm roll film to record the fluoroscopic image.
The ratio of the number of light photons at the output phosphor as compared with the input phosphor is the a. brightness gain b. flux gain c. minification gain d. conversion factor
ANS: B Flux gain is the ratio of the number of light photons at the output phosphor as compared with the input phosphor.
Inspecting the protective curtain, Bucky slot cover, and fluoroscopic timer are part of the a. performance quality control testing b. operational quality control testing c. supervisory d. performance quality control testing and operational quality control testing
ANS: B Inspecting the protective curtain, Bucky slot cover, and fluoroscopic timer are part of the operational quality control testing.
When operated in magnification mode, the electrostatic lenses have ________ of a negative charge. a. less b. more c. the same amount as usual d. one half
ANS: B Magnification of the fluoroscopic image occurs when the electrostatic lenses have more voltage applied, creating a more negative charge.
The formula for minification gain is a. minification gain = input phosphor diameter / output phosphor diameter b. minification gain = input phosphor diameter2 / output phosphor diameter2 c. minification gain = output phosphor diameter / input phosphor diameter d. minification gain = output phosphor diameter2 / input phosphor diameter2
ANS: B Minification gain = input phosphor diameter2 / output phosphor diameter2.
Performance quality control testing should be done by a a. radiographer b. medical physicist c. radiologist d. student radiographer
ANS: B Performance quality control testing should be done by a medical physicist.
Distortion of the fluoroscopic image that appears as unequal magnification is a. noise b. pincushion appearance c. vignetting d. magnification
ANS: B Pincushion appearance is the distortion of the fluoroscopic image that appears as unequal magnification.
A light-sensitive semiconducting device that generates an electrical charge when stimulated by light and stores this charge in a capacitor is the a. anode of the camera tube b. charge coupled device (CCD) c. cathode of the camera tube d. x-ray tube
ANS: B The CCD is a light-sensitive semiconducting device that generates an electrical charge when stimulated by light and stores this charge in a capacitor.
Semiconductor capacitors made of metal oxide are components of the a. camera tube b. CCD c. image intensifier d. x-ray tube
ANS: B The charge-coupled device (CCD) includes metal oxide semiconductor capacitors.
The commercial fluoroscope was developed by a. Rutherford b. Edison c. Newton d. Einstein
ANS: B The commercial fluoroscope was invented by Thomas Edison in 1896.
Which of the following has a rectangular field of view and a wider dynamic range? a. Conventional image intensifier. b. Flat-panel detector in place of image intensifier. c. There is no difference between the two.
ANS: B The flat-panel detector has a rectangular field of view and a wider dynamic range.
The electronic vacuum tube that converts the remnant x-ray beam to light, then to electrons, then back to light, increasing the light intensity in the process is the a. x-ray tube b. image intensifier c. recording system d. mirror optics
ANS: B The image intensifier is an electronic vacuum tube that converts the remnant beam to light, then to electrons, then back to light, increasing the light intensity in the process
The image intensifier was introduced in the a. 1920s b. 1950s c. 1970s d. 1980s
ANS: B The image intensifier was introduced in the 1950s.
The diameter of the input phosphor typically measures between a. 5 and 10 cm b. 15 and 30 cm c. 40 and 65 cm d. 75 and 100 cm
ANS: B The input phosphor typically measures between 15 and 30 cm, or approximately 6-12 inches across.
In LCD monitors, the number of TFTs is equal to the a. number of crystals in the liquid crystal layer b. number of pixels displayed c. Lp/mm of resolution d. display line system
ANS: B The number of TFTs is equal to the number of pixels displayed
The __________________ absorbs electrons and emits light. a. input phosphor b. output phosphor c. photocathode d. accelerating anode
ANS: B The output phosphor absorbs electrons and emits light.
This part of the image intensifier is made of silver-activated zinc cadmium sulfide. a. Input phosphor. b. Output phosphor. c. Photocathode. d. Accelerating anode.
ANS: B The output phosphor is made of zinc cadmium sulfide.
The diameter of the output phosphor is approximately a. 1 cm b. 2.5 cm c. 5 cm d. 25 cm
ANS: B The output phosphor measures approximately 2.5 cm or 1 inch in diameter.
The recording device that "photographs" the image off of the output phosphor is the a. cassette spot filming b. film cameras for spot filming c. videotape d. flat panel detector
ANS: B The photospot (film) camera is a static imaging system that is used with an optical lens system incorporating a beam-splitting mirror. When the spot-film exposure switch is pressed, the beam-splitting mirror is moved into place, diverting some of the beam toward the photospot camera and exposing the film.
The radiographer may be responsible for the ________________ inspection of the fluoroscopic equipment for quality control purposes. a. performance b. operational c. supervisory d. performance and operational
ANS: B The radiographer may be responsible for the operational inspection of the fluoroscopic equipment for quality control purposes.
The television is capable of resolving approximately ___________. a. 0.5-.75 Lp/mm b. 1-2 Lp/mm c. 3 Lp/mm d. 5 Lp/mm
ANS: B The television monitor can resolve approximately 1-2 Lp/mm.
In terms of resolution, the weakest part of the fluoroscopic system is the a. image intensifier b. television monitor c. camera tube d. CCD
ANS: B The television monitor has the least amount of spatial resolution of all the components of the fluoroscopic system.
Typical fluoroscopic systems have spatial resolution capabilities in the range of a. 2-3 Lp/mm b. 4-6 Lp/mm c. 7-9 Lp/mm d. 10-12 Lp/mm
ANS: B Typical fluoroscopic systems have spatial resolution capabilities in the range of 4-6 Lp/mm.
Magnification of the fluoroscopic image results in improved a. brightness b. spatial resolution c. contrast d. exposure
ANS: B Using the magnification mode improves spatial resolution of the fluoroscopic image.
A large fill factor refers to a. the entire detector being filled with x-rays b. the entire detector needing a large amount of x-rays to produce an image c. a large area of the pixel being sensitive to x-rays d. a small area of the pixel being sensitive to x-rays
ANS: C A large fill factor refers to a large area of the pixel being sensitive to x-rays. This is important to flat panel fluoroscopy.
When the electron beam sweeps the anode and travels back and forth across, from top to bottom, it is moving in a ___________ pattern. a. sweep b. brush c. raster d. rooster
ANS: C A raster pattern sweeps the anode in a path from left to right, from the top to the bottom.
A disadvantage of using magnification mode during fluoroscopy is a. the image has less resolution b. the image brightness is inconsistent c. the patient receives additional dose d. the image has increased noise
ANS: C Additional x-ray photons must leave the patient and be absorbed by the image intensifier when magnification mode is used, resulting in increased patient dose.
The function of the fluoroscopic unit that maintains the overall appearance of the fluoroscopic image (contrast and brightness) by automatically adjusting the kilovoltage peak (kVp), milliamperage (mA), or both is a. DQE b. APR c. ABC d. AEC
ANS: C Automatic brightness control (ABC) maintains the brightness and contrast of the fluoroscopic image during the study.
The formula for brightness gain is a. brightness gain = minification gain - flux gain b. brightness gain = minification gain / flux gain c. brightness gain = minification gain × flux gain d. None of these
ANS: C Brightness gain = minification gain × flux gain.
Each capacitor in a CCD represents a(n) a. line b. image c. pixel d. electric charge
ANS: C Each capacitor in a CCD briefly stores an electric charge that represents a pixel in the digital image.
Flat panel detector fluoroscopy units operate at what mA? a. 2- 5 mA b. 10-30 mA c. 50-1200 mA d. 1500-2000 mA
ANS: C Flat panel detector fluoroscopy units operate at 50-1200 mA.
Fluoroscopic equipment should be inspected every a. week b. month c. 6 months d. year
ANS: C Fluoroscopic equipment should be inspected every 6 months.
___________ imaging is used to view the human body in real time, accomplished with fluoroscopy as opposed to radiography. a. Static b. Still c. Dynamic d. Colorized
ANS: C Fluoroscopy allows imaging of anatomy in motion, dynamic imaging.
Before the image intensifier, the operator may have worn _____ goggles to make it easier to see the dim fluoroscopic image. a. blue b. green c. red d. yellow
ANS: C Goggles with red lenses allowed the operator's eyes to adjust to the dark, making it easier to see the dim image from the fluoroscope.
When the electron beam is sweeping the anode, if the electron beam and light from the output phosphor are incident on the same place at the same time, _____________ through the target to the signal plate. a. x-rays are produced b. the image is magnified c. electrons are transmitted d. light photons are transmitted
ANS: C If the electron beam encounters light as it sweeps across the target plate, electrons (an electric current) will be transmitted.
The term that means an expression of the degree to which the image is made smaller from input phosphor to output phosphor. is the a. brightness gain b. flux gain c. minification gain d. conversion factor
ANS: C Minification gain is an expression of the degree to which the image is minified (made smaller) from input phosphor to output phosphor. This characteristic makes the image appear brighter because the same number of electrons are being concentrated on a smaller surface area.
More advanced fluoroscopy systems use a flat-panel detector a. to record the spot images during fluoroscopy b. to record the overhead images following fluoroscopy c. in place of the image intensifier d. in addition to the image intensifier
ANS: C More advanced fluoroscopy systems use a flat-panel detector in place of the image intensifier.
Photoemission occurs at the a. input phosphor b. output phosphor c. photocathode d. accelerating anode
ANS: C Photoemission, when electrons are emitted in response to the presence of light, occurs at the photocathode
______________ refers to how long each exposure lasts. a. Pulsed fluoroscopy b. Pulse rate c. Pulse width d. Dose rates
ANS: C Pulse width refers to the length of each pulse. Think of this as how long each exposure lasts.
In fluoroscopy, shape distortion is caused by a. angling the x-ray tube b. angling the image intensifier in the fluoroscopic tower c. inaccurate control or focusing of the electrons released at the periphery of the photocathode, and the curved shape of the photocathode d. inaccurate control or focusing of the electrons released at the periphery of the photocathode, and the flat shape of the photocathode
ANS: C Shape distortion during fluoroscopy is the result of inaccurate control or focusing of the electrons released at the periphery of the photocathode, and the curved shape of the photocathode.
The purpose of a beam-splitting mirror is to a. view the fluoroscopic image on more than one television b. reduce the intensity of the image from the output phosphor c. allow spot filming to be done during fluoroscopy d. all of these
ANS: C The beam-splitting mirror is used during fluoroscopy when a spot image is to be recorded on a photospot or cine camera.
Which of the following is true about the CCD used in digital fluoroscopy? I. The CCD is more light sensitive with a higher DQE value. II. The CCD exhibits less noise and no spatial distortion. III. The CCD has higher spatial resolution. IV. The CCD requires more radiation to create an image. a. the CCD is more light sensitive with a higher DQE value and CCD exhibits less noise and no spatial distortion only. b. the CCD is more light sensitive with a higher DQE value and the CCD has higher spatial resolution only. c. the CCD is more light sensitive with a higher DQE value, CCD exhibits less noise and no spatial distortion, and the CCD has higher spatial resolution only. d. the CCD is more light sensitive with a higher DQE value, CCD exhibits less noise and no spatial distortion, and the CCD requires more radiation to create an image only. e. the CCD is more light sensitive with a higher DQE value, CCD exhibits less noise and no spatial distortion, the CCD has higher spatial resolution, and the CCD requires more radiation to create an image.
ANS: C The charge-coupled device is more sensitive to the light from the output phosphor as it has a higher DQE. The CCD exhibits less noise with no spatial distortion. The CCD has higher spatial resolution and requires less radiation to create an image (less dose).
The fiberoptic bundle or optical lens system is used to a. deliver the image from the camera to the television monitor b. record the fluoroscopic image c. link the output phosphor and camera or CCD d. none of these
ANS: C The fiberoptic bundle or optical lens system is used to link or couple the camera or CCD to the output phosphor of the image intensifier.
In image-intensified fluoroscopy units the method for viewing the fluoroscopic image is by a. using a handheld device b. looking directly at the output phosphor c. using a television monitor d. using a mirror-optics system
ANS: C The fluoroscopic image is viewed by looking at a television monitor.
This part of the image intensifier absorbs light and produces electrons. a. Input phosphor. b. Output phosphor. c. Photocathode. d. Electrostatic focusing lenses.
ANS: C The photocathode absorbs light and produces electrons.
The _______________________ is bonded directly to the input phosphor. a. input phosphor b. output phosphor c. photocathode d. accelerating anode
ANS: C The photocathode is attached directly to the input phosphor.
This part of the image intensifier is made of cesium and antimony compounds. a. Input phosphor. b. Output phosphor. c. Photocathode. d. Electrostatic focusing lenses.
ANS: C The photocathode is made of cesium and antimony compounds.
Which of the following contains a thin layer of pixels instead of a liquid crystal layer, with each pixel containing three neon and xenon gas-filled cells? a. Cathode ray tube monitor. b. Liquid crystal display (LCD) monitor. c. Plasma monitor. d. Radiographic film.
ANS: C The plasma monitor contains a thin layer of pixels instead of a liquid crystal layer, with each pixel containing three neon and xenon gas-filled cells.
The purpose of the________________________ is to convert the electronic signal from the camera tube or CCD into a visible image. a. image intensifier b. fiberoptic bundle c. television monitor d. anode of the vidicon tube
ANS: C The purpose of the television monitor is to convert the electronic signal from the camera tube or CCD back into a visible image.
The target layer is a photoconductive layer made of antimony trisulfide in ______ tubes. a. x-ray b. CCD c. vidicon d. plumbicon
ANS: C The target layer is a photoconductive layer made of antimony trisulfide in vidicon tubes.
Typical television monitors are a. 300 line systems b. 450 line systems c. 525 line systems d. 875 line systems
ANS: C Typical television monitors are 525 line systems.
A loss of brightness around the edge of the fluoroscopic image caused by the curve of the photocathode is a. noise b. pincushion appearance c. vignetting d. magnification
ANS: C Vignetting is the loss of brightness around the periphery of the fluoroscopic image.
Digital fluoroscopy is improved by using a. a vidicon camera b. videotape c. a beam-splitting mirror d. a charge-coupling device (CCD)
ANS: D A CCD used for converting the light image to an electronic image greatly improved digital imaging.
An electron gun can be found in the a. television monitor b. CCD c. vidicon camera d. television monitor and vidicon camera
ANS: D A camera tube and a television monitor both use electron guns.
What feature automatically adjusts the tube current (mA), voltage (kVp), filtration, and pulse width to maintain radiation exposure to the flat panel detector? a. Pulsed fluoroscopy b. Last image hold c. Frame averaging d. None of these
ANS: D AERC automatically adjusts the tube current (mA), voltage (kVp), filtration, and pulse width to maintain radiation exposure to the flat panel detector.
____________ is measured in cd/m2/mR/s. a. Brightness gain b. Flux gain c. Minification gain d. Conversion factor
ANS: D Conversion factor is an expression of the luminance at the output phosphor divided by the input exposure rate, and its unit of measure is the candela per square meter per milliroentgen per second (cd/m2/mR/s).
Frame averaging is a. an operation that reduces overall patient dose b. an operation that increases overall patient dose c. an operation that reduces image noise by averaging multiple image frames together d. an operation that reduces overall patient dose and an operation that reduces image noise by averaging multiple image frames together
ANS: D Frame averaging is an operation that reduces overall patient dose and image noise by averaging multiple image frames together.
In LCD monitors, the liquid crystal layer sandwiched between polarizing layers contains crystals that are in an unorganized and twisted state, but become __________ when electric current is applied. a. unorganized and twisted b. unorganized and untwisted c. organized and twisted d. organized and untwisted
ANS: D In LCD monitors, the liquid crystal layer sandwiched between polarizing layers contains crystals that are in an unorganized (twisted) state, but become organized (untwisted) when electric current is applied
If the input phosphor measures 30 cm and the output phosphor measures 2.5 cm, what is the minification gain? a. 8.3 b. 12 c. 69.2 d. 144
ANS: D Minification gain = input phosphor diameter2/output phosphor diameter2. In this case, minification gain = 302/2.52.
The analog-to-digital converter a. takes the video (analog) signal and divides it into binary language that the computer "understands." b. determines the contrast resolution of the system c. is necessary for the computer to process and display the image d. all of these
ANS: D The ADC converts analog data (electrical current) to digital data (1s and 0s). Each ADC has a set number of bits that determine image contrast resolution and is necessary for the computer to process and display the image.
What information during fluoroscopy should be documented in the patient's record? 1. Total amount of fluoroscopy time 2. Cumulative air kerma 3. Dose-area product a. total amount of fluoroscopy time and cumulative air kerma only b. total amount of fluoroscopy time and dose-area product only c. cumulative air kerma and dose-area product only d. total amount of fluoroscopy time, cumulative air kerma, and dose-area product
ANS: D The DAP/KAP and cumulative air kerma provide radiation exposure data and need to be recorded in the patient's medical record.
The _____________________ is designed to set the electron stream in motion at a constant velocity, and is located very close to the output phosphor. a. input phosphor b. output phosphor c. photocathode d. accelerating anode
ANS: D The anode is located very close to the output phosphor.
Which of the following is required in the indirect-capture detector? a. Amorphous silicon photodetector. b. Thin film transistor (TFT) array. c. A scintillator that uses cesium iodide or gadolinium oxysulfide as the phosphor. d. All of these.
ANS: D The cesium iodide amorphous silicon indirect-capture detector requires a scintillator with cesium iodide or gadolinium oxysulfide as the phosphor, an amorphous silicon photodetector, and a TFT array layered onto a glass substrate that include the readout, charge collector, and light-sensitive elements.
The ________________ is (are) found along the entire length of the image intensifier. a. input phosphor b. output phosphor c. photocathode d. electrostatic focusing lenses
ANS: D The electrostatic focusing lenses are located at various locations along the length of the image intensifier tube.
The image intensifier improved fluoroscopy by a. making the image easier to see because it is brighter b. making the image easier to see because it is bigger c. allowing indirect viewing of the fluoroscopic image d. making the image easier to see because it is brighter and allowing indirect viewing of the fluoroscopic image
ANS: D The fluoroscopic process was improved when the image intensifier made the image significantly brighter and allowed the operator to view the image without standing in the path of the x-ray beam.
The image intensifier is located a. next to the x-ray tube used for fluoroscopy b. beneath the x-ray table c. on a shelf just inside the room d. inside the fluoroscopic tower
ANS: D The image intensifier is located inside the fluoroscopic tower; whereas the x-ray tube used during fluoroscopy is located beneath the x-ray table.
For detectors to produce high-quality fluoroscopic images, they must be able to a. respond very quickly b. maintain a large fill factor c. have application-specific integrated circuits for noise reduction d. all of these
ANS: D To produce quality fluoroscopic images with digital detectors, they have to be able to respond quickly to the presence of x-rays, maintain a large fill factor, and have an ASIC in place to reduce noise.
Flat-panel detectors for fluoroscopic imaging can be the a. cesium iodide amorphous silicon indirect-capture detector b. amorphous selenium direct-capture detector c. cesium and antimony direct-capture detector d. cesium iodide amorphous silicon indirect-capture detector and amorphous selenium direct-capture detector e. cesium iodide amorphous silicon indirect-capture detector and cesium and antimony direct-capture detector
ANS: D Two forms of flat-panel detectors may be used for fluoroscopic applications: the cesium iodide amorphous silicon indirect-capture detector and the amorphous selenium direct-capture detector.
The ability to adjust the size of the field of view without exposing the patient to radiation is known as: a. frame averaging b. last image hold c. digital subtraction d. virtual collimation
ANS: D Virtual collimation allows the displayed field of view to be further adjusted without exposing the patient to additional radiation.
Which of the following is an advantage of flat panel detectors used in fluoroscopy? a. Much lighter and more compact. b. Produce a digital signal directly. c. Less electronic noise. d. 60 times larger operational dynamic range because they do not exhibit veiling glare. e. All of these.
ANS: E The flat panel detectors used in fluoroscopy are much lighter and more compact, they produce a digital signal directly (no need for a camera tube or ADC), and because it is a digital system producing a digital signal, absent of the electronic components of the old II system, there is less electronic noise. The flat panel detector has 60 times larger operational dynamic range than image intensifier systems and because of this do not exhibit veiling glare.
T or F: Age has no effect on an image intensifier because everything takes place in a vacuum.
ANS: F As an image intensifier ages, it deteriorates and requires more radiation to produce the same level of image brightness.
T or F: Each electron that interacts with the output phosphor results in significantly fewer light photons being produced in comparison with the number of light photons it took to release that electron.
ANS: F Each electron that interacts with the output phosphor results in significantly more light photons being produced in comparison with the number of light photons it took to release that electron.
T or F: The electron gun in the television monitor sends out a steady stream of electrons to activate the fluorescent screen.
ANS: F The electron gun in the television monitor sends out a constantly changing stream of electrons to activate the fluorescent screen, allowing display of various levels of brightness.
T or F: The input phosphor and photocathode form a flat surface.
ANS: F The input phosphor and photocathode form a curved surface so that the electrons all travel the same distance to the output phosphor.
T or F: When using magnification mode, the operator needs to set the exposure factors higher to compensate for the reduced diameter useful input phosphor.
ANS: F The need for increased exposure to the input phosphor when using magnification mode is automatically addressed by the ABC
T or F: The purpose of a camera tube or CCD is to record the fluoroscopic image.
ANS: F The purpose of a camera tube or CCD is to convert the output phosphor image to an electronic signal that can then travel to the television monitor.
T or F: The radiographer is responsible for performance and operational quality control testing.
ANS: F The radiographer is responsible for operational quality control testing. The medical physicist is responsible for performance quality control testing.
T or F: When a CCD is exposed to light, it generates and briefly stores light energy.
ANS: F When a CCD is exposed to light, it generates and briefly stores an electrical charge.
T or F: Automatic exposure rate control (AERC) is used in digital fluoroscopy and is similar to automatic brightness control (ABC).
ANS: T Like automatic brightness control (ABC) used in older image intensified units, automatic exposure rate control (AERC) serves a similar function in modern fluoroscopy.
T or F: Pulse rate refers to how many pulses occur per second of operation.
ANS: T Pulse rate refers to how many pulses occur per second of operation. Think of this as how many exposures occur per second.
T or F: The ABC can be slow in responding, seen as a brief delay in the brightness adjustment.
ANS: T The automatic brightness control can often be seen lagging behind changes in the intensity of the x-ray exposure to the image intensifier.
