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Physics Fluoro Exam

QuestionAnswer
Photoelectric emission: is the emission of electrons from an illuminated surface
at what stage of image intensified fluoroscopy is the number of image-forming photons lowest? entering the input phosphor
image intensifier brightness gain increases with increasing: flux gain
when an image intensifier receives x-rays at the input phosphor what is emitted at the output phosphor? visible light
which of the following is the input phosphor of image intensifiers? cesium iodide
which of the following is the output phosphor of image intensifiers? zinc cadmium sulfide
which of the following is the component of the image intensifier responsible for focusing the electron beam?` electrostatic lens
The ability of an image intensifier to enhance image illumination is called: brightness gain
the magnification gain of an image intensifier increases with increasing: input phosphor size
which of the following is a representative brightness gain for an image intensifier? 20,000
if an image intensifier is described as a 25/12 tube, 25/12 refers to which of the following? diameter of the input phosphor in centimeters
when a multi focus image intensifier is operated in the magnification mode: the electron focal point is closer to the input phosphor
an image that displays vignetting: is dim around the periphery
with a multi focus image intensifier in the magnification mode: spatial resolution is improved
What is the photoemissive component of image intensified fluoroscopy? electrons from light
which of the following is photoconductive? target
what is the principal disadvantage of coupling the television camera to the image intensifier with the use of fiber optics? photospot camera cannot be used
which of the following refers to the image intensifier input phosphor? cesium iodide
which is a critical component in optically coupling an image intensifier with a photospot camera? objective lens
what is the most important component of a television monitor? cathode ray tube
vertical television resolution is limited principally by which of the following? lines per frame
the electron beam in a television camera tube is produced by which of the following means? thermionic emission
what is the camera tube most used in television fluoroscopy? vidicon
place the following in proper sequence for image intensified fluoroscopy: 1. electric signal to light 2. electrons to light 3. light to electric signal 4. light to electrons 5. xray to light 5,4,2,3,1
which of the following applies to the output phosphor? light emitted
the bucky slot covers of a fluoroscopic unit is a: a. cassette holder b. film changer c. film support device d. protective device d. protective device
the ratio of the number of light photons at the output phosphor to the number of X-rays at the input phosphor is the: a. brightness gain b. illumination gain c. flux gain c.
_________ refers to the time delay of moving the II and seeing the new image on the monitor. a. film delay b. image lag c. phosphorescence b.
warping and distortion at outer region of II due to a repulsion of electrons and the curvature of the II is called a : a. brightness gain b. minification c.electrostatic charge d. pincushion artifact d. pincushion artifact
The II input phosphor is made of: a. NaI b. ZnCdS c. TLD d. CsI d.
the II output phosphor is made of: a. NaI b. ZnCdS c. TLD d. CsI B
the brightness gain of an II tube does NOT depend on the: a. patient dose b. efficiency of the photocathode c. voltage across the tube A
Typical values for modern IIs do not include: a. minification gains of 100 b. flux gains of 50 c. contrast ratios of 2:1 d. brightness gains of 5000 C
If the entrance skin exposure rate of an II operated in the 30-cm mode is 1 R/min, the ESE rate in the 15-cm mode would be: A. 1/4 R/min B. 1/2 R/min C. unchanged D. 2 R/min E. 4 R/min E
if a 25-cm diameter II has a brightness gain of 5,000 then the flux gain is approximately: a. 500 b. 50 c. 5 B
changing the magnification mode of an image intensifier from 30cm to 15cm in fluoroscopy will normally increase: a. entrance skin exposure b. distortion c. vignetting d. image brightness a
the reason for interlacing two fields to form one frame in a conventional TV system is to reduce the: a. patient dose b. motion artifacts c. quantum mottle d. flicker d
Vertical resolution of a standard north american TV is: a. >horizontal resolution b. .7x60 fields per second c. .7x262.5 line pairs c
the horizontal resolution of a TV system is primarily determined by the: a. image brightness b. bandwidth c. number of TV lines b.
the vertical resolution of a TV system is primarily determined by the: a. image brightness b. bandwidth c. number of TV lines c
in 35-mm cardiac cine, for a constant film density, patient entrance skin exposure is reduced by increasing the: a. acquisition frame rate b. kV c. mA d. grid ratio b. kV
The limiting spatial resolution in fluoroscopy can be improved by increasing the: a. grid ratio b. II input size c. radiation dose level d. kV e. none of the above e
T or F? fluoroscopic xray tubes are designed to operate for longer periods of time at much lower mA, as compared to a typical diagnostic tube true
T or F? fluoroscopy doesn't require the use of a grid false
T or F? angiographic xray tubes are different from general diagnostic imaging tubes in that the tubes must be able to withstand increased heat units while providing excellent detail true
T or F? states are permitted to have a more strict regulatory requirement on X-ray equipment than the federal government requires true
T or F? exceeding 10R/min is permitted by federal and state law in certain circumstances true
t or f? for an image intensifier, the composition of the output phosphor is typically the same as the composition of the input phosphor false
t or f? the typical kV range in a fluoroscopic tube as compared to a diagnostic tube, is similar true
t or f? the fluoroscopic tube is typically below the patient's table true
t or f? quantum mottle is a blotchy or grainy appearance caused by excessive radiation to create a uniform image false, caused by not enough radiation
t or f? the patient's table is the greatest source of scatter in a fluoroscopic procedure false, the patient is
The input screen absorbs ____ and emits ________. xray photons, light photons
electrostatic lenses are used to accelerate and focus: a. light photons b. xray photons c. electrons c
the II output phosphor is made of : a. NaI b. TLD c. ZnCdS c
standard fluoroscopic mA range is commonly: a. .5-5.0 b. 5-10 c. 10-100 a
the photocathode absorbs ______ and emits ________. light photons; electrons
the edge distortion problem in image intensification tubes is called: A. magnification b. minification c. vignetting c
for a stationary fluoro xray unit, the focal spot of the X-ray tube must be at least ____ away from the entrance point of the patient 12" (30cm)
for a c-arm fluoro X-ray unit, the focal spot of the X-ray tube must be at least ____ away from the entrance point of the patient 12" (30cm)
for lead aprons, the minimum allowed lead equivalency thickness required by law is _____mm 0.25 mm
in fluoroscopy, when the image intensifier button is selected for magnification, the method by which magnification is accomplished is by: moving the focal point of the electrons accelerated in the II away from the output phosphor
the purpose and function of an image intensifier as used in fluoro is to: a. convert X-rays to electrons b. act as a phosphor to expose film c. convert one X-ray at the input into thousands of light photons at the output c
this type of camera operated by recording a series of static images at high speed: a. cine camera b. cinema-type c. photomulitplier d. image intensifier a
the input phosphor of an image intensifier is composed of _____ and the output phosphor is composed of ______. a. CsI; CsI b. CsI; ZnCdS c. ZnCdS; Csl b
________ refers to the time delay of moving the II and seeing the new image on the monitor. a. flicker b. cine c. lapse d. lag d
fluoroscopy is a _______ radiographic examination. a. dynamic b. screening c. static d. more than one of the above a
fluoroscopy is mainly operated by the: a. radiographer b. radiologist c. physicist a
Created by: taylos84