Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
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
PRI-II
AEC/APR
| Question | Answer |
|---|---|
| Why was AEC originally developed? | To provide consistency in exposure and images |
| Which AED works by using a gas-filled chamber? | Ionization chamber system |
| Where is the sensor located in an AED with a gas filled chamber? | Between the patient and the IR |
| Where is the sensor located in an AED that converts light to electrical signals? | Behind the IR |
| AED that convert light to electrical signals are considered? | Exit type |
| AED that use gas filled chambers are considered what type of AED? | Entrance type |
| AEC controls what factor? | Time only |
| Which AED works by converting photons to light and then electrical signals? | Phototimers |
| Which AED is considered the first generation device? | Phototimers |
| 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 |
| With film screen radiography which factor would be adjusted to manipulate the contrast? | KVP |
| 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 |
| What is the appropriate setting for backup time/mAs? | 150%-200% of the expected exposure |
| 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 |
| 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 |
| 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% |
| The typical minimum response time on modern x-ray equipment: | 1 ms |
| What is the most common cause for repeating images done with film screen and AEC: | Patient centering |
| What is the optimal KVP starting point for small extremities? | 60 kVp |
| How does increased kVp affect density (film screen) or exposure (digital imaging)? | There is no change to density |
| 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 |
| The predetermined amount of radiation reaching the detector is known as being _________ and who sets it? | Calibrated Service personnel |
| Who determines the standards for calibration of machine? | Department |
| The two basic types of AEC systems: | -Phototimers -Ionization chamber |
| Most common type of AEC system used today? | Ionization chamber |
| Most reliable type of AEC system is ________: | Ionization chamber |
| Type of AEC system least prone to failure: | Ionization chamber |
| Phototimer AEC systems use ________? | PMT or PD |
| Which AEC system uses a fluorescent screen and a device that converts the light to electricity? | Phototimers |
| Phototimers are also known as __________ type devices: | Exit |
| _______ detectors are light paddles coated in fluorescent material: | Phototimers or Exit-type devices |
| The fluorescent material used in phototimer systems is comprised of what two materials? | Lucite with phosphors |
| What component of the phototimer (Exit type) system converts light to electrical signals: | Photomultiplier or photodiode |
| 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 - |
| The electrical charges are __________ to the radiation received by light paddles: | Proportional |
| All AEC systems use ________, they are also called what other names: | Detectors Sensors Cells |
| The AEC devices that measure the amount of radiation transmitted: | Sensors or cells |
| 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 |
| Electrical charge is proportional to the radiation received in the ______ _______: | Ion chamber |
| AEC affects what factor reaching the IR: | Quantity |
| kVp controls what three factors: | -Contrast -Penetration -Patient Exposure |
| A decrease mA can be used for what two reasons? | -Increase time -Change FSS |
| When kVp is decreased what will happen to time, mAs & patient exposure? | All increase |
| When kVp increases all other factors ________? | Decrease |
| Adequate kVp must be selected to ______ & _______? | -Penetrate the anatomical part -Produce adequate contrast |
| Increased mA does what to time? | Decreases |
| Increased time ________ mA? | decreases |
| The shortest exposure time a system can produce is known as: | Minimum response time |
| Minimum response time is used for: | -Pediatrics -Motion control |
| 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 |
| The maximum exposure time allowed during an AEC examination is known as _______: | Backup time |
| Phillips uses density controls of (-) or (+) 1-4, each increment is roughly? | 10%-15% |
| If density controls are being used routinely to achieve adequate exposure, what needs to happen? | Equipment needs to be recalibrated |
| 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 |
| If more than one sensor/cell is used the measure of radiation and electrical signal is ________: | Averaged |
| Improper patient centering can result in: | Underexposure or overexposure |
| The detector size is set by ______: | Manufacture |
| Over collimation can result in _______ _______: | Prolonged exposure |
| If AEC is calibrated for a slow IR and a fast IR is used the result will be __________: | Overexposure |
| If AEC is calibrated for a fast IR and a slow IR is used the result will be _________: | Underexposure |
| Are APR and AEC the same? | No |
| APR stands for: | Anatomically programmed radiography |
| APR can include both _____ and _________ techniques: | AEC & Manual |
| APR can or can not be alter once selected: | Can be adjusted by tech once a selection has been made |
| _____ is a preprogramed set of factors: | APR |
| APR operates the _____ on all equipment: | Same |
| _____ is controlled by integrated circuit or computer chip that has been programmed with exposure factors for different exposures and projections: | APR |
| ________ are established guidelines used by the radiographer to select standardized manual or AEC exposure factors for each type of radiographic examination: | Exposure technique chart |
| Exposure technique charts are used to provide what two purposes? | Consistent quality images & reduce repeats |
| Factors on the expsoure technique chart must include: | -kVp -mAs (possibly seperated) -Type of IR -Grid -SID -Possibly FSS |
| Standardization of technique charts must be done within _________: | The dept. |
| For technique charts to work efficiently, what two things must occur? | -Equipment must be functioning properly -Proper measurements must be taken |
| Measurements should be taken from which portion of the anatomical structure being examined? | -The midpoint or -The thickest portion |
| What are the two types of technique charts? | -Variable kVp/Fixed mAs -Fixed kVp/Variable mAs |
| Baseline kVp should be increased by ____ for every _____: | -2 -1 cm |
| What are the disadvantages of a variable kVp/fixed mAs technique chart? | -Changing kVp also affect contrast -Less accuracy at extreme ends -Part penetration |
| Variable kVp/Fixed mAs charts are effective with which two types of examinations? | -Pedis -Small extremities |
| At what kVp range is more effective to change kVp rather than mAs? | Lower level |
| 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 |
| 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 |
| _____ ____ are not standardized, they are meant to provide a common range of values for different anatomical areas: | Optimal kVp ranges |
| 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 |
| 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 |
| Conventional radiography demonstrates ______? | Superimposition of structures |
| Conventional tomography demonstrates _________? | Unsuperimposed structure, by blurring structures above and below a specific plane |
| Main uses of tomography? | Nephrotomography study to visualize kidney stones |
| How does linear tomography work? | The IR and tube move in opposite directions to blur structure above and below the specific plane of interest |
| The principal advantage of tomography is ______? | Improved contrast resolution |
| A larger tomographic angle will result in _______? | More blurring of the objects above and below the fulcrum point |
| A smaller tomographic angle will result in ________? | Less blurring of the objects above and below the fulcrum point |
| The larger the tomo angle the ________ the tomographic slice: | Thinner |
| The tomo angle and the tomo slice have a ________ relationship: | Inverse |
| The smaller the tomo angle the ________ the tomo slice: | Thicker |
| 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 |
| Zonography is used what what type of examinations? | Chest and renal examinations |
Created by:
akhernandez19