In each blank, try to type in the
word that is missing. If you've
typed in the correct word, the
blank will turn green.
If your not sure what answer should be entered, press the space bar and the next missing letter will be displayed. When you are all done, you should look back over all your answers and review the ones in red. These ones in red are the ones which you needed help on. Question: The major reason that image intensified fluoroscopy is is that is allows for:Answer: dynamic viewing (to see in motion) Question: Portable intensified fluoroscopy used for diagnostic purposes must not exceed _______ at the table top?Answer: 5R/min (do not assume ABC unless ) Question: Which type of vision is most commonly during conventional fluoroscopic exams?Answer: photopic Question: as the illumination of the light source increases, visual acuity __________?Answer: Question: the time over which the human eye can store a visual image is termed ________ time.Answer: Question: of the following structures is first to intercept light incident on the eye:
a. rod
b. iris
c. cornea
d. conesAnswer: c. cornea Question: the normal view distance for vision is:Answer: 12-15 Question: in general, during conventional examinations, the preferred technique is:
a. high kVp, low Ma
b. high kVp, low mAs
c. low kVp, high mAs
d. low kVp, high mAAnswer: a. high kVp, low Question: which of the following properties are associated with cones rather than rods?
a. contrast . color detection
c. visual acuity
d. all of the aboveAnswer: d. all the Question: how long does it take the fluoro to move from the horizontal to the vertical position?Answer: 20-30 Question: visible light:
a. is not part of the electromagnetic spectrum
b. has higher energy than x-rays
c. is the only part of the spectrum we can see
d. has lower energy than radio waves.Answer: c. is the only part of the electromagnetic spectrum we can Question: most modern image intensifiers use an input fluorescent layer that is composed of:Answer: cesium Question: the of light energy into a proportional amount of electrons is accomplished by a/an:Answer: photocathode Question: the acceleration of the stream inside the image intensifier requires a potential different(voltage) of :Answer: 25 Question: the output screen of an image intensifier functions to convert ________ into _______.Answer: electrons; Question: the target-to-panel and -to-skin distance shall not be less than:Answer: 12 Question: the squared of input screen to output screen size is called:Answer: Question: a 9-in input screen and a 1-in output screen increase brightness _______ times.Answer: 81 (9 squared/1 squared) Question: the point in the image intensifier tube the electrons cross over is termed the:Answer: focal point Question: in order to prevent light from scattering back to the photo-cathode of the image intensifier, a thin sheet of aluminum is placed onto the:Answer: output phosphor (so that light does not emit back to the -cathode. only e- can get through to excite the phosphor) Question: which of the following can be used to brightness gain?
a. a higher x-ray beam intensity
b. decrease minification ratio
c. increase accelerating voltage
d. increase minificationAnswer: d. increase Question: the focus of the electron stream in the image intensifier tube is accomplished by placing a ______ charge on the electrostatic lens.Answer: Question: distortion which with an image intensifier tube that demonstrates a dimmer density image at the periphery is called:Answer: vingnetting Question: the random pattern of scattered , which often results in an image intensifier tube that has the appearance of "snow" or "crawling ants" is:Answer: noise Question: the ratio of the luminescence in candelas of the phosphor t the input exposure rate in mR/sec defines:Answer: conversion Question: the output phosphor electrons into:Answer: light Question: the light exposure rate at the output phosphor will increase with increased _________. Answer: x-ray tube current (increase mA=increase xray photons striking phosphor=increase light photons given off by output phoshor Question: proper collimation of the fluoroscopic x-ray beam will:
a. decrease patient exposure
b. reduce scatter radiation
c. improve image . all the aboveAnswer: d. all the Question: for fluoro equipment with automatic exposure rate control, the x-ray tube current and potential shall be monitored at :Answer: once a Question: statistical fluctuations in the radiographic image which result in a appearance is called:Answer: quantum Question: the resolution of cesium iodide tubes is approximately __ lp/mm.Answer: 4 lp/mm Question: which of the following cannot reduce patient exposure AND operator exposure?
a. restricting the x-ray beam "on" time to a .
b. lowest mA and highest kVp
c. restricting the x-ray beam to the smallest size.
d. patient-screen distance to a maximumAnswer: d. keeping patient-screen distance to a Question: a photocell located between the image intensifier and the television camera system that is to maintain a range of brightness is a:Answer: Question: in order to maintain image clarity, the path of electron flow from the -cathode to the output phosphor is controlled by:Answer: lens Question: image intensifier input phosphor differs from the output phosphor in that the phosphor:
a. is much larger than output
b. emits electrons, output emits light
c. absorbs electrons, output absorbs light photons
d. is a fixed size, output size veryAnswer: a. is much larger than the Question: the total brightness gain of an image intensifier is a result of (1) flux gain, (2) minification ratio, (3) focusing gain.
a. 1
b. 2
c. 1 & 2
d. 1 & 3
e. 1, 2, & Answer: c. 1 and Question: the image which is produced at the input side of the TV camera is scanned by means of a/an:Answer: electron Question: each from of a TV picture consists of _________ scanninng linesAnswer: 525 lines Question: the screen of the TV camera tube converts the light image from the image intensifier into a/an:Answer: electronic Question: the electronic signal which carries the info from the TV camera to the is termed the:Answer: video Question: in the TV monitor, an electron gun repeats the pattern of the TV camera tube's onto a/an:Answer: screen Question: in order to ensure the proper eye integration a frame must be completed every _____ secondsAnswer: 1/30 seconds. 30 per second Question: in order to prevent the flicker effect during viewing of the TV image, a technique called __________ is used.Answer: scanning Question: which of the following are TV tubes?
a. vidicon
b. image orthicon
c. plumbicon
d. all the aboveAnswer: d. all of the Question: the beam in the TV camera is produced by:
a. thermionic emission
b. photoemission
c. electoemission
d. photoconductionAnswer: a. thermionic Question: the electron beam in the TV is controlled by the:
a. deflecting coils
b. electrostatic coils
c. focusing coils
d. all the aboveAnswer: d. all the above. all listed are the same thing Question: the target assembly of the TV camera tube consists of:
a. . target
c. signal plate
d. all the aboveAnswer: d. all the Question: which of the following will send the video signal?
a. window
b. target
c. signal plate
d. Answer: c. signal Question: in the optical coupling arrangement, which is nearest the TV camera tube?
a. objective lens
b. camera leans
c. beam splitter
d. Answer: b. camera Question: when the video signal is modulated, that means that its ___________ is changing in a controlled fashion.
a. intensity
b. frequency
c. amplitude
d. all the aboveAnswer: d. all the Question: the electron beam of the camera is _______ with the TV monitor.Answer: Question: one TV frame is equal to:
a. 1 TV field
b. 2 TV fields
c. 252.5 . 17 milisecondsAnswer: b. 2 TV Question: the fluoroscopic TV at a frame rate of:Answer: 30 /sec
Question: horizontal TV resolution is limited principally by the:
a. frame rate
b. field rate
c. . lines per frameAnswer: c. bandpass Question: the recording head of the video tape recieves a changing electronic signal which is transformed into a changing:
a. magnetic field
b. electronic pulse
c. video signal
d. Answer: a. magnetic field. anything to do with VHS uses magnetism Question: the exposure rate shall be measured ____ above the table.
a. 1 in
b. 1 cm
c. 1 ft
d. none of the aboveAnswer: d. none of the Question: the minimum height of the barrier is:Answer: 7 feet Question: secondary barriers are only necessary for:
a. radiographic units
b. combined R/F units
c. tomographic units
d. all the above
e. none of the Answer: d. all the Question: if the x-ray tube is above the table, the exposure rate shall be measured at________ above the table.Answer: 12 (30 cm) Question: when the automatic exposure rate control is used, the useful beam exposure rate shall be measured with a phantom equivalent to________ intercepting the useful beam.
a. 12 in of water
b. 7 7/8 in of water
c. 9 in of water
d. 12 in of luciteAnswer: c. 9 in of Question: when the TPD is increased from 12in to 18in, the skin entrance exposure will be reduced by:
a. 30%
b. 60%
c. 40%
d. none of the Answer: b. 60% Question: fluoroscopic operators shall restrict the beam "on" time to a minimum. doubling the exposure time will also _______ the exposure to the patient.
a. quadruple
b. one-half
c. double
d. one-fourthAnswer: c. Question: the intensity of the x-ray beam at the table top of a fluoroscope should not exceed _______R/min for each mA of tube current operating at 80 kVp.Answer: 2.2 R/min Question: a certain x-ray tube, at some given kilovoltage peak, delivers 4 milliroentgen per 1 second at 40in of distance. At 20 inch distance, the radiation output from the x-ray beam will be:
a. 16mR/mAs
b. 8mR/mAs
c. 2mR/mAs
d. 1mR/mAsAnswer: a. 16mR/mAs half distance=4 times the Question: during fluoroscopic image intensification, the technologist should restrict the x-ray beam to the smallest size practicable. doubling the field will result in the patient exposure:Answer: Question: the intensity of radiation to the square of the distance. as one moves away from the x-ray source, he/she will receive less radiation because:Answer: the x-ray beam diverges from its source Question: which of hte following is directly proportional to the delivered to the patient?Answer: Question: if 3gm of tissue absorb 300ergs of x-ray , what is the dose?Answer: 1 Rad Question: provisions regarding mobile fluoro are: (1)machine cannot be operated at a skin distance <18in (2)image intensification must be provided (3)conventional screens are not permitted (4) impossible to operate when collimator/diaphragm is not in placeAnswer: 2, 3, & Question: fluoroscopic equipment with an AEC control shall not be operable at any combination of tube and current in excess of:Answer: 10R/min Question: women : (1)1st 3 mo of preg most important (2)actual dose received by fetus<mother (3)risks to unborn baby considered small (4)no worry about sterility/child bearingAnswer: 1,2,3,4 Question: fluoro operator exposure to scattered is directly proportional to:Answer: patient Question: isoexposure contours during fluoroscopy will show that at a distance of 3 ft from the head of the table, the radiographer will :Answer: 50mR/hr Question: Compton scatter is the interaction of:
a. the incident photon and the valence electron
b. the high-speed electron and k-shell electron
c. the incident photon and the k-shell the scattered photon and the k-shell electronAnswer: a. the incident and the valence electron Question: advantage of using a film badge: (1)inexpensive (2)reusable (3)provides a record (4)can detect problems (5)provides an objective review
a. 1,2,3
b. 1,2,4
c. 2,3,4
d. 1,3,4,5Answer: d. 1,3,4,5 Question: possible disadvantages of pocket dosimeter: (1)no permanent record(2)frequent recharging required (3)subject to discharge (4)range of measurement limited.
a. 1,2
b. 1
c. 1,3,4
d 1,3
e 1,2,3,4Answer: e. 1,2,3,4 Question: when the c-arm for an anteroposterior chest in high direction from the tube is there the most radiation?Answer: 135 degrees fro the beam Question: which method of shielding is best during fluoroscopy?Answer: shaped, contact Question: increasing fluoroscopic x-ray tube current is mA will (1) provide brighter image (2)increase the patient exposure (3)decrease the operator exposure (4)increase exposure rate at the output phosphor.
a. 1,2
b. 1,2,3
c. 1,2,4
d. 1,2,3,4Answer: c. 1,2,4 Question: increasing the peak voltage will (1) increase penetrating power of x-ray beam(2)reduce pt skin exposure (3)decrease radiation exposure at the output phosphor(4)allow for the use of x-ray tube current
a. 1,2
b. 1,2,3
c. 1,2,4
d. 1,3,4
e. 1,2,3,4Answer: c. 1,2,4 Question: when x-rays are toward the patient, most are:Answer: absorbed by the Question: the dead-man type exposure switch (1)terminates the exposure when pressure is (2)operates by circuit closing contact maintained by continuous pressure(3)circuit will be closed when the operator dies (4)is an electromagnetic relay contact.
Answer: 1,2 Question: when the operational "boost" is , the equipment shall not be operable at any combo of tube current and potential that will result in an exposure rate in excess of:
a. 10R/min
b. 5R/min
c. 2.2R/min
d. none of the aboveAnswer: d. none of the . 20R/min Question: x-ray tube housing must be so constructed the leakable radiation at a distance of 1 from the target cannot exceed:
a. 100 mR/hr
b. 100 R/hr
c. 10 R/hr
d. 10 mR/hrAnswer: a. 100 mR/hr Question: the bucky slot cover/proctive curtain should have at least _________ equivalent materialAnswer: .25mm Question: the mA setting for fluoroscopy is less than:Answer: 5 Question: the operator must monitor the tube current and at least:Answer: once each Question: genetic dose to:Answer: effects exhibit in future offspring of who have been irradiated. Question: all of the following affect patient exposure except:
a. 3 generator
b. collimation
c. target-to-panel distance
d. exposure time
Answer: a. 3-phase Question: a high radiation area is any area accessible to individuals in which there exists radiation at such levels that an individual could receive in any 1 hour a dose to the body in excess of:Answer: d. Question: the is a unit of:Answer: Question: the genetically significant dose is a factor of which of the following parameters, (1)xray examination rate (2)mean gonadal dose per examination (3)number of chromosomes damaged (4)number of children:
a. 1,3,4
b. 2,3
c. 1,2,4
d. 1,2,3
e. 3,4Answer: c. 1,2,4 Question: radiosensitivity of the body in influenced by all of the except:
a. type of radiation and dose rate
b. size of cell
c. total dose of body receives
d. type of cell being irradiatedAnswer: b. size of Question: what is the maximum exposure a pregnant occupational worker may receive during the 9 months of .Answer: 500 Question: which type of table-top significantly reduces patient exposure:Answer: fiber Question: if the output is 128 mR/hr at 12mA of tube current, what is the intensity at 15mA?Answer: 160 mR/hr Question: If 4 grams of tissue absorb 400 ergs of x-rays, what is the dose? Answer: 1 rad
(1 rad = 100 ergs/gram; 400 ergs/4 = 1 rad) Question: Convert 4 mGy to Answer: 400 mrads
(100 rads = 1 Gy, 100 = 1 mGy) Question: 7.5 Gy to radsAnswer: 750 rads
(100 rads = 1 Gy) Question: 0.6 Sv to rem
Answer: 60 rem
(100 rem = 1 Sv) Question: Portable fluoroscopy used for diagnostic purposes must not exceed __/min at 30 cm from the input phosphor. Answer: Question: Which type of vision is most commonly employed during conventional fluoroscopic ? Answer: (cones; day vision) Question: As illumination of the light source increases, visual acuity _______.
Answer: A. Increases
(photopic range always greater acuity than ) Question: The time over which the human eye can a visual image is termed:Answer: time Question: Which of the following is first to intercept light incident on the eye?Answer: Question: In general, during conventional fluoroscopic , the preferred technique is:
A. High kVp, low mA
B. High kVp, low mAs
C. Low kVp, high mAs
D. Low kVp, high mAAnswer: A. High kVp, low mA (time is not set as a technical factor, but is dynamically) Question: Which of the following properties are associated with , rather than rods?
A. Contrast perception
B. Color detection
C. Visual acuity
D. All of the aboveAnswer: D. All of the Question: Visible light:
A. Is not a part of the electromagnetic spectrum
B. Is higher energy than x-rays
C. Is energy than radio waves
D. None of the above Answer: D. None of the Question: The conversion of light energy into a proportional amount of is accomplished by:
A. An electron gun
B. A photomultiplier tube
C. Electrostatic lenses
D. A photocathode Answer: D. photocathode Question: The of the electron stream inside the image intensifier requires a potential of about:
A. 2.5 volts
B. 25 volts
C. 2.5 kilovolts
D. 25 kilovolts Answer: D. 25 Question: The output phosphor of an image intensifier converts ________ to ________.
A. Light to electrons
B. X-rays to light
C. Electrons to light
D. X-rays to electrons Answer: C. to light Question: The -to-panel and target-to- skin distance SHALL not be less than:
A. 12”
B. 18”
C. 30”
D. 50” Answer: A. 12 Question: The squared ratio of input screen to output screen size is called:
A. Minification
B. Flux
C. Magnification
D. Answer: A. Minification Question: A 9” input screen and 1” output screen increases brightness
A. 9 times
B. 18 times
C. 81
D. None of the above Answer: C. 81 Question: Light distortion which occurs with an image intensifier that demonstrates a dimmer density at the periphery is called:
A. Interlacing
B.
C. Pincushion effect
D. Manual effectAnswer: B. Question: Intensity of output phosphor (candelas) Intensity at input phosphor (mrad/sec)
A. Brightness gain
B. Conversion
C. Flux gain
D. Minification Answer: B. conversion Question: The intensity at the output phosphor will with:
A. Collimation
B. mA
C. Filtration
D. Rotation Answer: B. mA
(assume mode, unless specified) Question: Proper collimation will:
A. Decrease patient exposure
B. Reduce scatter radiation
C. Improve image . All of the above Answer: D. all of the Question: Statistical variations in the radiographic image which result in a grainy appearance is termed:
A. Contrast resolution
B. Edge
C. Quantum mottle
D. Tube leakage Answer: C. mottle Question: Which does not reduce patient and operator exposure?
A. Reduced “on” time
B. Low mA, high kVp
C. Decreased patient-screen distance
D. Increased patient-screen Answer: D. Increased patient-screen Question: The input and output phosphors differ in:
A. Size
B. What energy they emit
C. None of the Answer: A. size Question: The electronic produced at the input side of a television camera is scanned by a/an:
A. Photocathode
B. Photomultiplier tube
C. Electrostatic lens
D. Electron gun Answer: D. gun Question: Each frame of a television image consists of:
A. 252 lines
B. 525
C. 1050 lines
D. 2250 lines Answer: B. 525 Question: The input of a television camera tube converts the light image from the image intensifier to:
A. An x-ray image
B. An electronic image
C. Visible image
D. None of the above Answer: B. an image Question: The electrical image from the target of the vidicon tube is scanned:
A. 525 times per second
B. 0.2 times per second
C. 10 per second
D. 30 times per second Answer: D. 30 per second Question: In order to prevent flicker during television viewing, a technique called ________ is used.
A. Amplification
B. Interlacing
C. Synchronization
D. Vignetting Answer: B. Question: Which of the following are television pick-up camera tubes?
A.
B. Plumbicon
C. Image orthicon
D. All of the above Answer: D. all of the Question: The exposure rate in fluoro shall not exceed _________ measured 30 cm from the input phosphor.
A. 2.5 rads/min
B. 5 rads/min
C. 10 rads/min
D. 20 rads/min Answer: B. 5 rads/min Question: The exposure rate in fluoro is allowable up to 10 rads/min in which of the following cases?
A. Magnification mode
B. ABC mode
C. High level control
D.
E. Exposure recording Answer: B. ABC mode
(Remember 5 R/min unless: ABC (10 R/min), boost (20 R/min), (unlimited) and image acquisition (unlimited)( Question: The exposure rate in fluoro should be measured using a phantom equivalent of:
A. 12”
B. 7 7/8” water
C. 12” lucite
D. 7 7/8” lucite Answer: D. 7 7/8” Question: The intensity of the x-ray beam at the fluoroscopy table top should not exceed ________ for each mA of tube current at 80 kVp.
A. 2.2 R/min
B. 2.5 R/min
C. 5 R/min
D. 10 R/min Answer: A. 2.2 R/min Question: Which of the following is directly proportional to the patient dose?
A. kVp
B. mA
C. Filtration
D. Target to distance (SID) Answer: B. mA Question: If 1 gram of tissue absorbs 300 ergs of x- ray energy, what is the dose?
A. 1 rad
B. 3 rad
C. 30 rad
D. 300 Answer: B. 3 rad
(1 rad = 100 ergs/gram) Question: In mobile fluoroscopy, the to skin distance must be at least:
A. 9”
B. 12”
C. 30”
D. 50” Answer: B. 12 Question: Fluoroscopic operator exposure is directly proportional to:
A. Beam intensity
B. Output phosphor
C. Image brightness
D. Patient exposure
E. All of the Answer: D. exposure Question: When x-rays are toward a patient, they are mostly:
A. Absorbed by the patient
B. Scattered by the patient
C. Absorbed by the operator
D. Absorbed by the air Answer: A. by the patient Question: X-ray tube must be constructed such that radiation leakage at 1 meter of the target does not exceed:
A. 100 mR/hr
B. 100 R/hr
C. 10 R/hr
D. 10 mR/hr Answer: A. /hour Question: The slot cover must be at least:
A. 0.25 mm Al
B. 0.25 mm Pb
C. 0.5 mm Al
D. 0.5 mm Pb Answer: B. 0.25mm Question: Genetic dose refers to:
A. Dose received by the patient’s
B. Dose that penetrate gonadal shielding
C. Dose that may exhibit effects in irradiated person’s offspring
D. Population dose Answer: C. Dose that may exhibit in irradiated person’s offspring Question: A “high radiation area” refers to an area in which an individual might receive a dose of greater than ___________ at 30 cm from the source:
A. 0.1 rem/min
B. 0.1 rem/hr
C. 1 rem/min Answer: B. 0.1 rem/hour Question: Radiosensitivity of tissue or cells is influenced by all of the following except:
A. Type of radiation
B. Rate of cell division
C. Type of cell
D. Differentiation
E. None of the above Answer: E. none of the Question: The diameter of the input phosphor to diameter of the output phosphor squared is the formula for:
A. Minification gain
B. Flux gain
C.
D. Brightness gain Answer: A. minification Question: Normal viewing distance for binocular vision is:
A. 4-8 inches
B. 8-10
C. 12-15 inches
D. 16-24 inches Answer: C. 12-15 Question: The primary advantage to using video disc recording is:
A. patient dose
B. Increase image resolution
C. Increase recording speed
D. Decrease examination time Answer: A. Reduce patient dose
(recording the image without using cine or spot reduces patient dose) Question: During fluoroscopy, the operator’s dose proportional to:
A. mA
B. Patient dose
C. kVp
D. Field size Answer: B. patient Question: The resolution of the fluoroscopic is calculated using:
A. Conversion factor
B. Bandpass
C. Kell factor
D. Line pair factor Answer: C. kell Question: State regulations require that all fluoroscopic tubes have a minimum of ________mm Al.
A. 0.5
B. 2.0
C. 1.5
D. 2.5 Answer: D. 2.5 Question: When the target-to-panel is increased, the patient dose is:
A. Increased
B. Decreased
C. Remains the same
D. Doubles Answer: B. decreased Question: Which of the following will decrease patient dose without affecting brightness?
A. Increasing TPD
B. Increasing kVp
C. Collimating
D. Increasing OID Answer: A. increase Question: Survey meters used to monitor exposure operate on the principle of: A. Luminscence
B. Fluorescence
C. Ionization
D. Thermal energy Answer: C. ionization Question: A strong correlation exists between and radiation dose received by the:
A. Thyroid
B. Skin
C. CNS
D. Bone marrow Answer: D. bone Question: The maximum exposure rate of a system is measured using:
A. 9” lucite
B. 7 7/8” water
C. 9” water
. Weekly fluoro phantom Answer: C. 9” water (or 7 7/8” ) Question: What are the annual occupational dose limitations for to:
- the skin & extremities ?
- the whole body ?
- the lens of the eye ?Answer: Skin: 50 Rem OR 0.5 Sv
WB: 5 Rem OR .05 Sv
Eye: 15 Rem OR .15 Question: What is/are the radiation unit(s) for?
- absorbed dose
- exposure / intensity in air
- dose equivalent / biological effectAnswer: AD: Gray / Rad
RE: Roentgen / Air : Rem / Sievert Question: ldentify radiation dose limits for occupational exposure to (a) individuals under 18 yrs of age and to (b) members of the public:Answer: 18 years of age: 10 % of Adult dose limits
Public: 0.1 Rem in a Year Question: When reporting the overexposure of individuals to (Incident Notification ), differentiate between the requirements of "lmmediate notification " and "24 hour notification" Answer: Immediate: effective dose equiv. of 25 Rems or more Call State Dept.
24: Total effective dose exceeding 5 Rems
Call State Dept within 24 hrs Question: List the levels that require either "immediate" or "twenty-four hour" notification be made to the CA
State, Dept of Health Services for: lmmediate / 24 hr
- whole body/ total effective dose
- eye dose
- shallow dose (skin/extremities)Answer: WB: Immediate = 25 Rems or More
24 hrs = Exceeding 5 Rems
Eye: = 75 Rems or More
24 hrs = Exceeding 15 Rems
SD: Immediate = 250 Rads or More
24 hrs = Exceeding 50 Rads Question: Records of radiation dose equivalents received by individuals must be kept / preserved for how long (what of time)?Answer: Question: X Ray must be registered within __ Days of acquisitionAnswer: 30 Question: If the dose is 5 mRem/min at a distance of 2’ from the source, what is the occupational dose at 4’?Answer: 1.25 mrem/min
- First recognize that the distance has , which means the dose is now 1/4th. – Divide 5 by 4
– Answer = 1.25 mrem/min Question: If the occupational dose is 5 mrem/min at a of 2’ from the source, what is the occupational dose at 3’? Answer: 2.22 mrem/min
– Set up the equation and solve for “x”:
• Intensity 1 / 2 = Distance 2 2 / Distance 1 2
• 5 mrem / x = 3 feet 2 / 2 feet 2
• 5 mrem / x = 9 / 4 feet
• 4/9) (5) = x • 2.22 = x
• Answer: 2.22 mrem/min Question: If the occupational dose is 4 mrem/min at 2.5’ away from the source, at what distance the technologist stand to reduce it their dose to 3 mrem/min? Answer: 2.88 ft
– Set up the equation and solve for “x”: • Int 1 / Int 2 = Dist2 2 / Dist 1 2
• 4 mrem/3 mrem = x 2 / 2.5 feet 2
• 1.33= x 2/6.25
• 1.33*6.25 =x2
• 8.31 = x 2
• √8.31 =x
• x=Answer: 2.88 Question: If the occupational dose during a 12 minute fluoroscopy procedure is 37 mrem at 2.5’ away from the source, what will it be at 5’ away from the ?
–Put your answer in mrem/minAnswer: 0.77 mrem/min
– , put the original dose rate in mrem/min
• 37 mrem/12 min = 3.08 mrem/min
– Then, recognize that the distance has doubled, which decreases the dose to 1/4th. • (3.08 mrem/min) / 4 = 0.77 mrem/min Question: The output of a fluoroscopy machine is measured to be 4.2 R/min at 80 kVp and 3 mA at the . Is this in compliance with the CA allowable exposure rate? Answer: YES
– First, remember that the maximum allowable exposure rate is 2.2 R/min per mA at 80 kVp. – At 3 mA, the max rate would be 6.6 R/min
– 4.2 R/min is less than the max allowable rate
– Answer: yes Question: In order to reduce a 100 mrad/min dose rate to 25 mrad/min, how many half-value must be added to the primary beam? Answer: 2 half-value layers
– One “half-value” layer would bring the dose to 50 mrad/min.
– One more -value” layer would bring the dose to 25 mrad/min.
– Answer: Two “half-value” layers Question: A 525-line monitor has a vertical resolution of actual 467 lines. What is the Kell Factor for this system? Answer: 0.89
– Kell factor = vertical resolution/total lines
– K = 467 / 525
– K = 0.89 Question: A 1000-line monitor system has a Kell Factor of 0.79. How many are resolved? Answer: 790 lines
• Kell factor = actual vertical resolution/total lines
• 0.79 = x / 1000
• 0.79 * 1000 = x
• 790 = x
• : 790 line Question: A patient’s dose was 6.2 rads during a 10- minute fluoroscopy exam in 12” mode. If the was done entirely in 9” magnification mode, what would have been the patient’s dose?
– Give your answer in rads/min Answer: 1.1 rads/min
•Put in rads/min
–6.2rads/10min=0.62rads/min
•Set up mag equation to find the factor:
–Dose Factor=Normal mode2/Mag mode2
-DF=12”2/9”2=144/81=1.77
•Multiply DF and original dose= mag mode dose:
– 1.77*0.62 rads/min=1.1rads/min Question: The input phosphor of an image intensifier is 6” and the phosphor is 1”. What is the minification gain? Answer: 36
–Mini gain = Input phos2/ Output gain = 6”2 / 1”2
–Min gain = 36 / 1
–Answer: Minification Gain = 36 Question: What is the gain of an image intensifier with a 12” input phosphor, 1” output phosphor and a flux gain of 3090?Answer: 444,960
•Brightness gain=min. gain * flux gain=(Input pho2/Output phos2) * flux gain
•Brightness gain = (122 / 12) * 3090
• Brightness gain = (144/1) * 3090
• Total brightness gain = 444,960 |
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Created by:
ingallsac
Popular Radiology sets