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IMAGE FINAL
Preassessment 4
| Question | Answer |
|---|---|
| Quantum noise seen in digital image with | severely lower than needed mAs |
| exposure time will ___ using AEC when pt thickness decreases | decrease |
| In CR reader unit, the IP is scanned with a(n): | neon helium laser |
| Lossy compression can be used for: | video recordings |
| An increase in mAs would ___ the ___ of the emission spectrum. | 1. increase 2. amplitude |
| Most target xrays are: | bremsstrahlung |
| difference in brightness levels or densities: | image contrast |
| What is the industry standard formula for calculating high voltage generator power? | Power = max mA (@100 kvp and 100 ms)*100kvp |
| Magnification always results in reduced ___. | spatial resolution |
| As spatial frequency increases, the object size ___ and the spatial resolution ___. | 1. decreases 2. increases |
| With digital imaging, exposure factors (do/do not) need to be adjusted in order to visualize soft tissue. | do not |
| HVL is lowered by a decrease in: | kVp |
| ISL has rhe same effect on optical density and xray: 1. intensity 2. exposure 3. quantity | 1, 2, 3 |
| ISL is the relationship between ___ and XR beam intensity. | distance |
| Accuracy of structural lines is determined by the images: | spatial resolution |
| The ___ image occurs first on the IR and the ___ image occurs following proper image development/processing. | 1. latent 2. manifest |
| During selection of the FSS the RT is really determining the: | actual size of filament used |
| Once the part has been penetrated, doubling the mAs results in ___ the exposure to the IR. | two times |
| CR reader sequence: 1. analog electrical signal sampled and digitized 2. Stored energy is released as visible light 3. PMT converts light energy to electrical signal | 2, 3, 1 |
| Image forming XRs include those which have been ___. | transmitted without interaction and scattered throughout compton interaction |
| optical density (overall blackness on an image) is primarily controlled by changing the ___. | mAs |
| With a fixed matrix CR reader system, changing a larger IP for the same FOV will result in: | larger pixels |
| 2 principal caracteristics of a medical image: | 1. spatial resolution (accuracy) 2. contrast resolution (visibility) |
| Post processing technique improves the visibility of small, high contrast structures. | edge enhancement (?) |
| What is the result of imaging a thicker part or pt? | more compton interactions |
| How often the analog signal is digitized is the: | sampling frequency |
| As compared to 3 phase XR unit, a single phase unit requires ___ exposure factors. | higher |
| high kVp results in: 1. less absorption and more transmission 2. less variation in XR intensities exiting pt 3. increased compton interactions 4. low contrast image | 1, 2, 3, 4 |
| Aplitude of emission spectrum with a ___ generator is ___ it is with a 3 phase generator | 1. single phase 2. lower than |
| An increase in kVp would ___ the ___ of the emission spectrum | 1. increase 2. amplitude and shift position of emission spectrum to the right |
| FS blur can be reduced by using: 1. small focal spot 2. shorter SID 3. longer OID | 1, 2, 3 |
| Increasing window width will result in: | lower contrast |
| In digital imaging, spatial resolution is limited by: | pixel size |
| How does added filtration affect the emission spectrum? | reduces amplitude and shifts to the right |
| Modern XR equipment the AEC systems minimum response time is typically: | 1 ms |
| decreasing the window level will result in an image with: | increased brightness |
| Lowering kVp ___ pt dose and ___ image contrast | 1. increases 2. increases |
| Recording detail is the term commonly used in digital imaging to describe the accuracy of structural lines for ___ imaging. | film-screen |
| The quality control standard for flat panel displays was released by___ in 1998 | VESA |
| The most accurate type of timer is the ___ timer. | electronic |
| beam attenuation is increased with a ___ energy XRB. | decreased |
| europium is the activator of the ___ | photostimulable phosphor |
| At energys below 40 keV the predominant XR interaction in soft tissue and bone is ___. | photoelectric absorption |
| radiographic contrast would be standardized with the: | fixed kv/ variable mas technique chart |
| Which factor affects exposure to the IR by altering the amount and penetrating ability of the XRB? | kVp |
| which auto exposure device works by converting XR photons first into light and then into an electrical signal? | Phototimer |
| The 3 main parts of the XR imaging system are the XR tube, ___ and ___ | 1. operating console 2. high voltage generator |
| The ___ is the source of radiation in th XR tube. | focal spot |
| The XRB that leaves the pt in the direction of the IR | remnant |
| computer system designed to distribute, store, and display digital imgs is: | PACS |
| When an img is distorted, ___ is decreased. | Spatial resolution |
| PACS | Picture Archiving and Communication System |
| The efficiency of XR production is ___ proportional to the tube current. | directly |
| formula for heat units for a 3 phase 6 pulse machine: | 1.35 x kVp x mA x seconds |
| What is the basic photometric unit: | Lumen |
| ___ can be assessed by only turning off the monitor in ambient light. | specular reflection |
| The ___ grid ratio should always be selected in order to most improve image contrast. | highest |
| When using a fixed kvp variable mas chart, mas needs to ___ if part thickness increases by 5cm. | double |
| Each anatomical part has an img histogram with a(n) ___ shape | characterisic |
| Digital fluoroscopic dose rate is ___ than that for continuous analog fluoroscopy | lower |
| The range of histogram data set that should be included in the displayed image is determined by the: | Values of interest |
| As mas increases, the quantity of radiation reaching the IR ___. | increases |
| Contrast is a quality related to the ___ of the image. | visibility |
| in digital radiography, the brightness of the image is determined by: | pixel values |
| changes in ___ result in directly proportional changes in the amplitude of the emission spectrum. | both mA and time |
| With CR, when the XR photons are absorbed by the phosphor, the ___ atoms become ionized. | europium |
| numerical value that is displayed on the processed image to indicate the level of XR exposure received on the digital IR | exposure indicator |
| Changing from 40 to 72 SID would result in ___ brightness and ___ contrast | 1. no change 2. no change |
| Electron interactions at the inner shell of the target atoms produce ___ radiation. | characterisitc |
| The CR reader is made of ___, ___, and ___ modules. 1. mechanical 2. chemical 3. optical 4. computer | 1, 3, 4 |
| in order to image a structure that is located anteriorly the body, it is best radiographed to minimize magnification by doing a(n) ___ projection. | PA |
| Compton scatter contributes to ___. | image fog |
| a SD trans is located on the ___ circuit | filament |
| The 4 steps of creating an image with computed radiography are ___. | metastable state, stimulate, read, erase |
| number of pixels per unit area: | pixel density |
| brems XRs produced by ___ at the target | slowing electrons |
| In order to become familiar with manual technical factors with AEC it is very helpful to pay attention to the : | mas readout |
| differential absorption in Dx imaging is primarily caused by ___. | photoelectric absorption |
| text data and email are generated at a ___ workstation n PACS | Radiology information system (RIS) |
| emission of light when stimulated by a high intensity laser beam is: | photostimulable luminescence |
| characteristic XRs are produced by ___. | releasing binding energy |
| A good reason to use AEC density control is to increase the exposure to the IR to compensate for improper centering. | no. |
| The ___ are outside of the glass envelope | stators |
| spatial resolution is improved with ___ pixel density | increased |
| the scattered XR from a compton interaction usually retains ___ of the energy of the incident photon | most |
| exit rad is converted to visible light with the ___ conversion detector: | indirect |
| a CCD used in digital fluoroscopy provides high: 1. spatial resolution 2. high SNR 3. high DQE | 1, 2, 3 |
| An outer-shell electron is ejected and the atom is ionized during ___ interactions. | compton |
| Changing from 8:1 to a 12:1 along with the appropriate adjustments will result in: 1. increased pt dose 2. an image with increased contrast 3. using more mas | 1, 2, 3 |
| The DR system sends the ___ signal directly to the computer. | digital |
| The filament is made of | tungsten |
| With CR, a higher sampling frequency results in___ pixel density and ___ spatial resolution | 1. increased 2. increased |
| aperture diagram with an attached elongated tube: | cylinder |
| The Task Group Report 18 is a procedure manual for ___. | testing digital display devices |
| Radiographic image quality is improved when the ___ is increased. | SID |
| A compensating filter is used to create ___ optical density with a body part of ___ thickness. | 1. uniform 2. non uniform |
| The filament in an xray tube is about ___ cm in length | 1-2 cm |
| The science of ___ is the study of the response of the human eye to light. | photometry |
| A technique chart should be established for: | each tube |
| Where can the DAP meter be found? | embedded in the collimator |
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lipscombsomi