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CA Fluoro Review
California Flurorscopy Exam Review
| Question | Answer |
|---|---|
| The major reason that image intensified fluoroscopy is employed is that is allows for: | dynamic viewing (to see anatomy in motion) |
| Portable intensified fluoroscopy used for diagnostic purposes must not exceed _______ at the table top? | 5R/min (do not assume ABC unless stated) |
| Which type of vision is most commonly employed during conventional fluoroscopic exams? | photopic |
| as the illumination of the light source increases, visual acuity __________? | increases |
| the time over which the human eye can store a visual image is termed ________ time. | integration |
| which of the following structures is first to intercept light incident on the eye: a. rod b. iris c. cornea d. cones | c. cornea |
| the normal view distance for binocular vision is: | 12-15 inches |
| in general, during conventional fluoroscopic examinations, the preferred technique is: a. high kVp, low Ma b. high kVp, low mAs c. low kVp, high mAs d. low kVp, high mA | a. high kVp, low mA |
| which of the following properties are associated with cones rather than rods? a. contrast perception b. color detection c. visual acuity d. all of the above | d. all the above |
| how long does it take the fluoro table to move from the horizontal to the vertical position? | 20-30 sec |
| visible light: a. is not part of the electromagnetic spectrum b. has higher energy than x-rays c. is the only part of the electromagnetic spectrum we can see d. has lower energy than radio waves. | c. is the only part of the electromagnetic spectrum we can see |
| most modern image intensifiers use an input fluorescent screen layer that is composed of: | cesium iodide |
| the conversion of light energy into a proportional amount of electrons is accomplished by a/an: | photocathode |
| the acceleration of the electron stream inside the image intensifier requires a potential different(voltage) of : | 25 kilovolts |
| the output screen of an image intensifier functions to convert ________ into _______. | electrons; light |
| the target-to-panel and target-to-skin distance shall not be less than: | 12 inches |
| the squared ratio of input screen to output screen size is called: | minification |
| a 9-in input screen and a 1-in output screen increase brightness _______ times. | 81 times (9 squared/1 squared) |
| the point in the image intensifier tube where the electrons cross over is termed the: | electron focal point |
| in order to prevent light from scattering back to the photo-cathode layer of the image intensifier, a thin sheet of aluminum is placed onto the: | output phosphor (so that light does not emit back to the photo-cathode. only e- can get through to excite the phosphor) |
| which of the following can be used to increase brightness gain? a. a higher x-ray beam intensity b. decrease minification ratio c. increase accelerating voltage d. increase minification | d. increase minification |
| the focus of the electron stream in the image intensifier tube is accomplished by placing a ______ charge on the electrostatic lens. | negative |
| distortion which occurs with an image intensifier tube that demonstrates a dimmer density image at the periphery is called: | vingnetting |
| the random pattern of scattered radiation, which often results in an image intensifier tube that has the appearance of "snow" or "crawling ants" is: | quantum noise |
| the ratio of the luminescence in candelas of the output phosphor t the input exposure rate in mR/sec defines: | conversion factor |
| the output phosphor converts electrons into: | light photons |
| the light exposure rate at the output phosphor will increase with increased _________. | x-ray tube current (increase mA=increase xray photons striking input phosphor=increase light photons given off by output phoshor |
| proper collimation of the fluoroscopic x-ray beam will: a. decrease patient exposure b. reduce scatter radiation c. improve image quality d. all the above | d. all the above |
| for fluoro equipment with automatic exposure rate control, the x-ray tube current and potential shall be monitored at least: | once a week |
| statistical fluctuations in the radiographic image which result in a grainy appearance is called: | quantum mottle |
| the resolution of cesium iodide image tubes is approximately __ lp/mm. | 4 lp/mm |
| which of the following cannot reduce patient exposure AND operator exposure? a. restricting the x-ray beam "on" time to a minimum. b. lowest mA and highest kVp c. restricting the x-ray beam to the smallest size. d. patient-screen distance to a maximum | d. keeping patient-screen distance to a maximum |
| a photocell located between the image intensifier and the television camera system that is designed to maintain a range of brightness is a: | photomultiplier |
| in order to maintain image clarity, the path of electron flow from the photo-cathode to the output phosphor is controlled by: | electrostatic lens |
| image intensifier input phosphor differs from the output phosphor in that the input 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 very | a. is much larger than the output |
| 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, & 3 | c. 1 and 2 |
| the electronic image which is produced at the input side of the TV camera is scanned by means of a/an: | electron gun |
| each from of a TV picture consists of _________ scanninng lines | 525 scanning lines |
| the input screen of the TV camera tube converts the light image from the image intensifier into a/an: | electronic image |
| the electronic signal which carries the info from the TV camera to the monitor is termed the: | video signal |
| in the TV monitor, an electron gun repeats the pattern of the TV camera tube's image onto a/an: | fluorescent screen |
| in order to ensure the proper eye integration a frame must be completed every _____ seconds | 1/30 seconds. 30 frames per second |
| in order to prevent the flicker effect during viewing of the TV image, a technique called __________ is used. | interlaced scanning |
| which of the following are TV camera tubes? a. vidicon b. image orthicon c. plumbicon d. all the above | d. all of the above |
| the electron beam in the TV camera is produced by: a. thermionic emission b. photoemission c. electoemission d. photoconduction | a. thermionic emissions |
| the electron beam in the TV camera is controlled by the: a. deflecting coils b. electrostatic coils c. focusing coils d. all the above | d. all the above. all coils listed are the same thing |
| the target assembly of the TV camera tube consists of: a. window b. target c. signal plate d. all the above | d. all the above |
| which of the following will send the video signal? a. window b. target c. signal plate d. photomultiplier | c. signal plate |
| in the optical coupling arrangement, which is nearest the TV camera tube? a. objective lens b. camera leans c. beam splitter d. mirror | b. camera lens |
| 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 above | d. all the above |
| the electron beam of the camera is _______ with the TV monitor. | syncronized |
| one TV frame is equal to: a. 1 TV field b. 2 TV fields c. 252.5 lines d. 17 miliseconds | b. 2 TV fields |
| the fluoroscopic TV operates at a frame rate of: | 30 frames/sec |
| horizontal TV resolution is limited principally by the: a. frame rate b. field rate c. bandpass d. lines per frame | c. bandpass |
| 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. current | a. magnetic field. anything having to do with VHS uses magnetism |
| the exposure rate shall be measured ____ above the table. a. 1 in b. 1 cm c. 1 ft d. none of the above | d. none of the above |
| the minimum height of the primary barrier is: | 7 feet |
| 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 above | d. all the above |
| if the x-ray tube is above the table, the exposure rate shall be measured at________ above the table. | 12 inches (30 cm) |
| 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 lucite | c. 9 in of water |
| 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 above | b. 60% |
| 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-fourth | c. double |
| 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. | 2.2 R/min |
| a certain x-ray tube, at some given kilovoltage peak, delivers 4 milliroentgen per 1 milliampere 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/mAs | a. 16mR/mAs half distance=4 times the dose |
| during fluoroscopic image intensification, the technologist should restrict the x-ray beam to the smallest size practicable. doubling the exposure field will result in the patient exposure: | doubling |
| the intensity of radiation varies to the square of the distance. as one moves away from the x-ray source, he/she will receive less radiation because: | the x-ray beam diverges from its point source |
| which of hte following is directly proportional to the exposure delivered to the patient? | mA |
| if 3gm of tissue absorb 300ergs of x-ray energy, what is the dose? | 1 Rad |
| provisions regarding mobile fluoro are: (1)machine cannot be operated at a skin distance <18in (2)image intensification must be provided (3)conventional fluoro screens are not permitted (4) impossible to operate when collimator/diaphragm is not in place | 2, 3, & 4 |
| fluoroscopic equipment with an AEC control shall not be operable at any combination of tube potential and current in excess of: | 10R/min |
| women employees: (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 bearing | 1,2,3,4 |
| fluoro operator exposure to scattered radiation is directly proportional to: | patient exposure |
| isoexposure contours during fluoroscopy will show that at a distance of 3 ft from the head of the table, the radiographer will recieve: | 50mR/hr |
| 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 electron d the scattered photon and the k-shell electron | a. the incident photon and the valence electron |
| advantage of using a film badge: (1)inexpensive (2)reusable (3)provides a permanent record (4)can detect problems (5)provides an objective review a. 1,2,3 b. 1,2,4 c. 2,3,4 d. 1,3,4,5 | d. 1,3,4,5 |
| possible disadvantages of pocket dosimeter: (1)no permanent record(2)frequent recharging required (3)subject to accidental discharge (4)range of measurement limited. a. 1,2 b. 1 c. 1,3,4 d 1,3 e 1,2,3,4 | e. 1,2,3,4 |
| when the portable c-arm for an anteroposterior chest in high direction from the tube is there the most radiation? | 135 degrees fro the primary beam |
| which method of gonadal shielding is best during fluoroscopy? | shaped, contact shield |
| 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 light exposure rate at the output phosphor. a. 1,2 b. 1,2,3 c. 1,2,4 d. 1,2,3,4 | c. 1,2,4 |
| 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 lower x-ray tube current a. 1,2 b. 1,2,3 c. 1,2,4 d. 1,3,4 e. 1,2,3,4 | c. 1,2,4 |
| when x-rays are directed toward the patient, most are: | absorbed by the patient |
| the dead-man type exposure switch (1)terminates the exposure when pressure is released(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. | 1,2 |
| when the operational "boost" is activated, 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 above | d. none of the above. 20R/min |
| x-ray tube housing must be so constructed the leakable radiation at a distance of 1 meter from the target cannot exceed: a. 100 mR/hr b. 100 R/hr c. 10 R/hr d. 10 mR/hr | a. 100 mR/hr |
| the bucky slot cover/proctive curtain should have at least _________ equivalent material | .25mm Pb |
| the mA setting for fluoroscopy is typically less than: | 5 mA |
| the operator must monitor the tube current and potential at least: | once each day |
| genetic dose refers to: | effects exhibit in future offspring of persons who have been irradiated. |
| all of the following affect patient exposure except: a. 3 phase generator b. collimation c. target-to-panel distance d. exposure time | a. 3-phase generators |
| 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 whole body in excess of: | d. 100mRem |
| the roentgen is a unit of: | exposure |
| 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 future children: a. 1,3,4 b. 2,3 c. 1,2,4 d. 1,2,3 e. 3,4 | c. 1,2,4 |
| radiosensitivity of the body in influenced by all of the following except: a. type of radiation and dose rate b. size of cell c. total dose of body receives d. type of cell being irradiated | b. size of cell |
| what is the maximum exposure a pregnant occupational worker may receive during the 9 months of gestation. | 500 mRem |
| which type of table-top material significantly reduces patient exposure: | carbon fiber |
| if the output intensity is 128 mR/hr at 12mA of tube current, what is the intensity at 15mA? | 160 mR/hr |
| If 4 grams of tissue absorb 400 ergs of x-rays, what is the absorbed dose? | 1 rad (1 rad = 100 ergs/gram; 400 ergs/4 grams = 1 rad) |
| Convert 4 mGy to mrads | 400 mrads (100 rads = 1 Gy, 100 mrads = 1 mGy) |
| Convert 7.5 Gy to rads | 750 rads (100 rads = 1 Gy) |
| Convert 0.6 Sv to rem | 60 rem (100 rem = 1 Sv) |
| Portable intensified fluoroscopy used for diagnostic purposes must not exceed __/min at 30 cm from the input phosphor. | 5R |
| Which type of vision is most commonly employed during conventional fluoroscopic exams? | photopic (cones; day vision) |
| As illumination of the light source increases, visual acuity _______. | A. Increases (photopic range always greater acuity than scotopic) |
| The time over which the human eye can store a visual image is termed: | Integration time |
| Which of the following structures is first to intercept light incident on the eye? | cornea |
| In general, during conventional fluoroscopic exams, the preferred technique is: A. High kVp, low mA B. High kVp, low mAs C. Low kVp, high mAs D. Low kVp, high mA | A. High kVp, low mA (time is not set as a technical factor, but is determined dynamically) |
| Which of the following properties are associated with cones, rather than rods? A. Contrast perception B. Color detection C. Visual acuity D. All of the above | D. All of the above |
| Visible light: A. Is not a part of the electromagnetic spectrum B. Is higher energy than x-rays C. Is lower energy than radio waves D. None of the above | D. None of the above |
| The conversion of light energy into a proportional amount of electrons is accomplished by: A. An electron gun B. A photomultiplier tube C. Electrostatic lenses D. A photocathode | D. photocathode |
| The acceleration 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 | D. 25 Kilovolts |
| 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 | C. Electrons to light |
| The target-to-panel and target-to- skin distance SHALL not be less than: A. 12” B. 18” C. 30” D. 50” | A. 12 inches |
| The squared ratio of input screen to output screen size is called: A. Minification B. Flux C. Magnification D. Conversion | A. Minification |
| A 9” input screen and 1” output screen increases brightness A. 9 times B. 18 times C. 81 times D. None of the above | C. 81 times |
| Light distortion which occurs with an image intensifier that demonstrates a dimmer density at the periphery is called: A. Interlacing B. Vignetting C. Pincushion effect D. Manual effect | B. Vignetting |
| Intensity of output phosphor (candelas) Intensity at input phosphor (mrad/sec) A. Brightness gain B. Conversion factor C. Flux gain D. Minification | B. conversion factor |
| The intensity at the output phosphor will increase with: A. Collimation B. mA C. Filtration D. Rotation | B. mA (assume manual mode, unless specified) |
| Proper collimation will: A. Decrease patient exposure B. Reduce scatter radiation C. Improve image quality D. All of the above | D. all of the above |
| Statistical variations in the radiographic image which result in a grainy appearance is termed: A. Contrast resolution B. Edge enhancement C. Quantum mottle D. Tube leakage | C. quantum mottle |
| 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 distance | D. Increased patient-screen distance |
| The input and output phosphors differ in: A. Size B. What energy they emit C. None of the above | A. size |
| The electronic image 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 | D. electron gun |
| Each frame of a television image consists of: A. 252 lines B. 525 lines C. 1050 lines D. 2250 lines | B. 525 lines |
| The input screen 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 | B. an electronic image |
| 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 times per second D. 30 times per second | D. 30 times per second |
| In order to prevent flicker during television viewing, a technique called ________ is used. A. Amplification B. Interlacing C. Synchronization D. Vignetting | B. interlacing |
| Which of the following are television pick-up camera tubes? A. Vidicon B. Plumbicon C. Image orthicon D. All of the above | D. all of the above |
| 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 | B. 5 rads/min |
| 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. Cineradiography E. Exposure recording | B. ABC mode (Remember 5 R/min unless: ABC (10 R/min), boost (20 R/min), magnification (unlimited) and image acquisition (unlimited)( |
| The exposure rate in fluoro should be measured using a phantom equivalent of: A. 12” water B. 7 7/8” water C. 12” lucite D. 7 7/8” lucite | D. 7 7/8” lucite |
| 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 | A. 2.2 R/min |
| Which of the following is directly proportional to the patient dose? A. kVp B. mA C. Filtration D. Target to panel distance (SID) | B. mA |
| 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 rad | B. 3 rad (1 rad = 100 ergs/gram) |
| In mobile fluoroscopy, the target to skin distance must be at least: A. 9” B. 12” C. 30” D. 50” | B. 12 inches |
| Fluoroscopic operator exposure is directly proportional to: A. Beam intensity B. Output phosphor C. Image brightness D. Patient exposure E. All of the above | D. patient exposure |
| When x-rays are directed 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 | A. Absorbed by the patient |
| X-ray tube housing 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 | A. 100mR/hour |
| The bucky 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 | B. 0.25mm Pb |
| Genetic dose refers to: A. Dose received by the patient’s gonads B. Dose that penetrate gonadal shielding C. Dose that may exhibit effects in irradiated person’s offspring D. Population dose | C. Dose that may exhibit effects in irradiated person’s offspring |
| 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 | B. 0.1 rem/hour |
| 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 stage E. None of the above | E. none of the above |
| The diameter of the input phosphor to diameter of the output phosphor squared is the formula for: A. Minification gain B. Flux gain C. Magnification D. Brightness gain | A. minification gain |
| Normal viewing distance for binocular vision is: A. 4-8 inches B. 8-10 inches C. 12-15 inches D. 16-24 inches | C. 12-15 inches |
| The primary advantage to using video disc recording is: A. Reduce patient dose B. Increase image resolution C. Increase recording speed D. Decrease examination time | A. Reduce patient dose (recording the image without using cine or spot films reduces patient dose) |
| During fluoroscopy, the operator’s dose increases proportional to: A. mA B. Patient dose C. kVp D. Field size | B. patient dose |
| The resolution of the fluoroscopic monitor is calculated using: A. Conversion factor B. Bandpass C. Kell factor D. Line pair factor | C. kell factor |
| 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 | D. 2.5 |
| When the target-to-panel distance is increased, the patient dose is: A. Increased B. Decreased C. Remains the same D. Doubles | B. decreased |
| Which of the following will decrease patient dose without affecting image brightness? A. Increasing TPD B. Increasing kVp C. Collimating D. Increasing OID | A. increase TPD |
| Survey meters used to monitor radiation exposure operate on the principle of: A. Luminscence B. Fluorescence C. Ionization D. Thermal energy | C. ionization |
| A strong correlation exists between leukemia and radiation dose received by the: A. Thyroid B. Skin C. CNS D. Bone marrow | D. bone marrow |
| The maximum exposure rate of a fluoroscopic system is measured using: A. 9” lucite B. 7 7/8” water C. 9” water . Weekly fluoro phantom | C. 9” water (or 7 7/8” lucite) |
| What are the annual occupational dose limitations for exposure to: - the skin & extremities ? - the whole body ? - the lens of the eye ? | Skin: 50 Rem OR 0.5 Sv WB: 5 Rem OR .05 Sv Eye: 15 Rem OR .15 Sv |
| What is/are the radiation unit(s) for? - absorbed dose - radiation exposure / intensity in air - dose equivalent / biological effect | AD: Gray / Rad RE: Roentgen / Air Kerma DE: Rem / Sievert |
| ldentify radiation dose limits for occupational exposure to (a) individuals under 18 yrs of age and to (b) individual members of the public: | 18 years of age: 10 % of Adult occupational dose limits Public: 0.1 Rem in a Year |
| When reporting the overexposure of individuals to radiation (Incident Notification ), differentiate between the requirements of "lmmediate notification " and "24 hour notification" | Immediate: Total effective dose equiv. of 25 Rems or more Call State Dept. 24: Total effective dose exceeding 5 Rems Call State Dept within 24 hrs |
| List the exposure 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) | WB: Immediate = 25 Rems or More 24 hrs = Exceeding 5 Rems Eye: Immediate = 75 Rems or More 24 hrs = Exceeding 15 Rems SD: Immediate = 250 Rads or More 24 hrs = Exceeding 50 Rads |
| Records of radiation dose equivalents received by individuals must be kept / preserved for how long (what period of time)? | Forever |
| X Ray equipment must be registered within __ Days of acquisition | 30 days |
| If the occupational dose is 5 mRem/min at a distance of 2’ from the source, what is the occupational dose at 4’? | 1.25 mrem/min - First recognize that the distance has doubled, which means the dose is now 1/4th. – Divide 5 by 4 – Answer = 1.25 mrem/min |
| If the occupational dose is 5 mrem/min at a distance of 2’ from the source, what is the occupational dose at 3’? | 2.22 mrem/min – Set up the equation and solve for “x”: • Intensity 1 / Intensity 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 |
| If the occupational dose is 4 mrem/min at 2.5’ away from the source, at what distance should the technologist stand to reduce it their dose to 3 mrem/min? | 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 ft |
| 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 source? –Put your answer in mrem/min | 0.77 mrem/min – First, 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 |
| The output of a fluoroscopy machine is measured to be 4.2 R/min at 80 kVp and 3 mA at the tabletop. Is this in compliance with the CA allowable exposure rate? | YES – First, remember that the maximum allowable exposure rate is 2.2 R/min per mA at 80 kVp. – At 3 mA, the max allowable rate would be 6.6 R/min – 4.2 R/min is less than the max allowable rate – Answer: yes |
| In order to reduce a 100 mrad/min dose rate to 25 mrad/min, how many half-value layers must be added to the primary beam? | 2 half-value layers – One “half-value” layer would bring the dose to 50 mrad/min. – One more “half-value” layer would bring the dose to 25 mrad/min. – Answer: Two “half-value” layers |
| A 525-line monitor system has a vertical resolution of actual 467 lines. What is the Kell Factor for this system? | 0.89 – Kell factor = actual vertical resolution/total lines – K = 467 / 525 – K = 0.89 |
| A 1000-line monitor system has a Kell Factor of 0.79. How many lines are resolved? | 790 lines • Kell factor = actual vertical resolution/total lines • 0.79 = x / 1000 • 0.79 * 1000 = x • 790 = x • Answer: 790 line |
| A patient’s dose was 6.2 rads during a 10- minute fluoroscopy exam in 12” mode. If the procedure was done entirely in 9” magnification mode, what would have been the patient’s dose? – Give your answer in rads/min | 1.1 rads/min •Put answer 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 |
| The input phosphor of an image intensifier is 6” and the output phosphor is 1”. What is the minification gain? | 36 –Mini gain = Input phos2/ Output phos2 –Min gain = 6”2 / 1”2 –Min gain = 36 / 1 –Answer: Minification Gain = 36 |
| What is the brightness gain of an image intensifier with a 12” input phosphor, 1” output phosphor and a flux gain of 3090? | 444,960 •Brightness gain=min. gain * flux gain •Brightness gain=(Input pho2/Output phos2) * flux gain •Brightness gain = (122 / 12) * 3090 • Brightness gain = (144/1) * 3090 • Total brightness gain = 444,960 |
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