AEC/APR
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| Why was AEC originally developed? | To provide consistency in exposure and images
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| Which AED works by using a gas-filled chamber? | Ionization chamber system
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| Where is the sensor located in an AED with a gas filled chamber? | Between the patient and the IR
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| Where is the sensor located in an AED that converts light to electrical signals? | Behind the IR
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| AED that convert light to electrical signals are considered? | Exit type
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| AED that use gas filled chambers are considered what type of AED? | Entrance type
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| AEC controls what factor? | Time only
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| Which AED works by converting photons to light and then electrical signals? | Phototimers
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| Which AED is considered the first generation device? | Phototimers
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| What would happen if film screen radiography exam required an exposure time faster than the minimum response time of the AEC sensors? | Image would be overexposed, because it would continue to to accept photons until the MRT was reached
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| With film screen radiography which factor would be adjusted to manipulate the contrast? | KVP
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| In digital radiography which factor would be adjusted to manipulate the contrast? | None, KVP does provide change, but it is not consistent. It is mainly controlled by computer-processing
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| What is the appropriate setting for backup time/mAs? | 150%-200% of the expected exposure
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| What is the purpose of backup time/mAs? | Safety feature in the event the equipment malfunctions of the tech does not use the appropriate technical factors
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| When using film screen, what happens when an outside detector is selected for an AP thoracic spine? | The system shuts off prematurely and the image appears underexposed
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| When doing a film screen study using AEC, what will happen to the density in the area of interest when changing from -1 to +1 density? | Density is increased by 50%
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| The typical minimum response time on modern x-ray equipment: | 1 ms
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| What is the most common cause for repeating images done with film screen and AEC: | Patient centering
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| What is the optimal KVP starting point for small extremities? | 60 kVp
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| How does increased kVp affect density (film screen) or exposure (digital imaging)? | There is no change to density
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| What are the basic functions of AEC: | -Radiation is transmitted thru pt. -Exit radiation is converted to electrical signal -Once predetermined amt of radiation is reached exposure is terminated
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| The predetermined amount of radiation reaching the detector is known as being _________ and who sets it? | Calibrated Service personnel
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| Who determines the standards for calibration of machine? | Department
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| The two basic types of AEC systems: | -Phototimers -Ionization chamber
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| Most common type of AEC system used today? | Ionization chamber
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| Most reliable type of AEC system is ________: | Ionization chamber
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| Type of AEC system least prone to failure: | Ionization chamber
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| Phototimer AEC systems use ________? | PMT or PD
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| Which AEC system uses a fluorescent screen and a device that converts the light to electricity? | Phototimers
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| Phototimers are also known as __________ type devices: | Exit
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| _______ detectors are light paddles coated in fluorescent material: | Phototimers or Exit-type devices
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| The fluorescent material used in phototimer systems is comprised of what two materials? | Lucite with phosphors
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| What component of the phototimer (Exit type) system converts light to electrical signals: | Photomultiplier or photodiode
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| Basic function of phototimer systems: | -Radiation interacts with paddles & produces light -Light is transmitted to remote PMT or PD -Light is converted to electric current & then amplified to electrical charge -Timer is tripped and exposure stops -
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| The electrical charges are __________ to the radiation received by light paddles: | Proportional
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| All AEC systems use ________, they are also called what other names: | Detectors Sensors Cells
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| The AEC devices that measure the amount of radiation transmitted: | Sensors or cells
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| Basic function of ionization chamber system: | -Ionization chamber is exposed to exit radiation -Air in chamber is ionized creating an electrical charge -Charge travels along wire to timer circuit -Timer is tripped and exposure stops when calibrated limit is reached
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| Electrical charge is proportional to the radiation received in the ______ _______: | Ion chamber
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| AEC affects what factor reaching the IR: | Quantity
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| kVp controls what three factors: | -Contrast -Penetration -Patient Exposure
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| A decrease mA can be used for what two reasons? | -Increase time -Change FSS
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| When kVp is decreased what will happen to time, mAs & patient exposure? | All increase
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| When kVp increases all other factors ________? | Decrease
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| Adequate kVp must be selected to ______ & _______? | -Penetrate the anatomical part -Produce adequate contrast
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| Increased mA does what to time? | Decreases
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| Increased time ________ mA? | decreases
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| The shortest exposure time a system can produce is known as: | Minimum response time
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| Minimum response time is used for: | -Pediatrics -Motion control
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| If mA is set too high to reach the minimum exposure time how will this affect film & digital? | -Film, will be too dark -Digital, EI #s out of range and pt. dose increased
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| The maximum exposure time allowed during an AEC examination is known as _______: | Backup time
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| Phillips uses density controls of (-) or (+) 1-4, each increment is roughly? | 10%-15%
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| If density controls are being used routinely to achieve adequate exposure, what needs to happen? | Equipment needs to be recalibrated
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| If a machine is calibrated for a 400 speed and a 200 screen speed is used, how will it affect the image and why? | It will take longer for the sensors to fill so the image will be overexposed
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| If more than one sensor/cell is used the measure of radiation and electrical signal is ________: | Averaged
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| Improper patient centering can result in: | Underexposure or overexposure
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| The detector size is set by ______: | Manufacture
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| Over collimation can result in _______ _______: | Prolonged exposure
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| If AEC is calibrated for a slow IR and a fast IR is used the result will be __________: | Overexposure
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| If AEC is calibrated for a fast IR and a slow IR is used the result will be _________: | Underexposure
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| Are APR and AEC the same? | No
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| APR stands for: | Anatomically programmed radiography
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| APR can include both _____ and _________ techniques: | AEC & Manual
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| APR can or can not be alter once selected: | Can be adjusted by tech once a selection has been made
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| _____ is a preprogramed set of factors: | APR
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| APR operates the _____ on all equipment: | Same
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| _____ is controlled by integrated circuit or computer chip that has been programmed with exposure factors for different exposures and projections: | APR
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| ________ are established guidelines used by the radiographer to select standardized manual or AEC exposure factors for each type of radiographic examination: | Exposure technique chart
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| Exposure technique charts are used to provide what two purposes? | Consistent quality images & reduce repeats
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| Factors on the expsoure technique chart must include: | -kVp -mAs (possibly seperated) -Type of IR -Grid -SID -Possibly FSS
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| Standardization of technique charts must be done within _________: | The dept.
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| For technique charts to work efficiently, what two things must occur? | -Equipment must be functioning properly -Proper measurements must be taken
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| Measurements should be taken from which portion of the anatomical structure being examined? | -The midpoint or -The thickest portion
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| What are the two types of technique charts? | -Variable kVp/Fixed mAs -Fixed kVp/Variable mAs
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| Baseline kVp should be increased by ____ for every _____: | -2 -1 cm
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| What are the disadvantages of a variable kVp/fixed mAs technique chart? | -Changing kVp also affect contrast -Less accuracy at extreme ends -Part penetration
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| Variable kVp/Fixed mAs charts are effective with which two types of examinations? | -Pedis -Small extremities
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| At what kVp range is more effective to change kVp rather than mAs? | Lower level
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| Advantages of a fixed kVp/variable mAs technique chart: | -Charts can be completed in patient groups vs individual 1 cm adjustments -every 4-5 cm increase in thickness mAs in adjusted by a factor of two
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| Optimal kVp ranges for the following anatomical parts; Chest, Neck, Abdomen, Sm. extremities, Lg. extremities, shoulder girdle, Hip/pelvis: | Chest=100-130, Neck=75-80, Abdomen=70-80, Small ext.=50-60,Large ext.=65-75,Shoulder girdle=70-80, Hip/pelvis=75-85
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| _____ ____ are not standardized, they are meant to provide a common range of values for different anatomical areas: | Optimal kVp ranges
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| Advantages to using fixed kVp/variable mAs charts: | -Easier to use -More consistency -Part penetration is mor accurate -More uniform contrast -Increased accuracy at the extreme measurement ends
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| Optimal kVp ranges for cervical, thoracic, lumbar/sacrum, coccyx, sternum/SC joints, Skull/headwork, ribs: | C-spine=70-80, T-spine=75-85, L-spine/Sacrum:AP/Obl=75-80, Lat=85-95, Spot=95-100, Coccyx=75-85, Sternum/SC joints: Obl=60-70, Lat=70-75, Skull/headwork=70-80, Ribs: Above=65-70, below=70-80
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| Conventional radiography demonstrates ______? | Superimposition of structures
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| Conventional tomography demonstrates _________? | Unsuperimposed structure, by blurring structures above and below a specific plane
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| Main uses of tomography? | Nephrotomography study to visualize kidney stones
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| How does linear tomography work? | The IR and tube move in opposite directions to blur structure above and below the specific plane of interest
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| The principal advantage of tomography is ______? | Improved contrast resolution
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| A larger tomographic angle will result in _______? | More blurring of the objects above and below the fulcrum point
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| A smaller tomographic angle will result in ________? | Less blurring of the objects above and below the fulcrum point
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| The larger the tomo angle the ________ the tomographic slice: | Thinner
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| The tomo angle and the tomo slice have a ________ relationship: | Inverse
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| The smaller the tomo angle the ________ the tomo slice: | Thicker
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| What is zonography? | When tomo angle of less than 10 degrees is used, it is utilized when subject contrst of the object is so low that a thin slice would result in poor image
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| Zonography is used what what type of examinations? | Chest and renal examinations
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