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
rad review #2
Image production 4.1 (quiz.98)
| Question | Answer |
|---|---|
| beam filtration exits in the form of _______ and ________ filtration | inherent added |
| How would the introduction of a 6 inch OID affect analog image contrast? | --Contrast would increase -Because due to the 6 inch air gap between the part and the IR, much of the scattered radiation emitted from the body will not reach the IR -Thus OID is acting like a low ratio grid and is increasing analog image contrast |
| To produce higher contrast in abdominal radiography, _______ kvp can be used. | lower |
| The likely cause of a grainy appearance (quantum noise/ mottle) is: | Low mAs and high kVp |
| Focal spot blur is greatest toward the __________ end ofthe xray beam | Cathode |
| The CR should be directed to the center of the part of greatest interest to avoid; | rotation distortion because anatomic details placed away from the path of the CR will be exposed by more divergent rays |
| Disadvantages of using lower kVp with higher mAs to compensate are: | -insufficient penetration(lower kvp) -increased patient dose (higher mAs) |
| T/F: Beam intensity/quantity/mAs is not related to differential absorption | True |
| Because 3-phase equipment has much higher effective voltage than single phase equipment, the 3-phase radiographwill have _______ contrast | lower |
| What type of xray imaging uses an area beam and a photostimulable phosphor as the IR? | CR |
| Spatial resolution is directly related to: | SID Because as SID increases so does spatial resolution because magnification decreases. |
| Spatial resolution is inversely (indirectly) related to: | Focal spot size because as focal spot size increases, spatial reolution decreases. |
| What is the relationship between tube current and spatial resolution? | Unrelated because tube current affects receptor exposure and is unrelated to spatial resolution |
| The factors that affect the sharpness of image detail are: | -focal spot size -SID -OID -Motion |
| Which law states that a particular mAs value, regardless of the miliamperage and exposre time used, will provide identical receptor exposure. | Reciprocity law |
| A pathologic condition is categorized as either __________ or ___________ | destructive (decrease is mass density in body) additive (increase in mass density in body (tumor)) |
| As kV increase, exposure latitude ( margin of error in exposure) | also increases |
| As kV increases, scatter radiation : | also increases |
| As kV increases, _____er scale contrast is produced | Longer |
| Resolution can be expressed as which units? | -Line-pairs per mm, -LIne spread function -Modulation transfer function |
| A magnified image that is diagnostic can be obtained only buy using a fractional spot of __mm or smaller | 0.3 mm |
| Exposure rate increases with an increase in | mA kVp |
| Exposure rates dcreases with an increase in ______ | SID |
| Shape distortion is influenced by the relationship between the ______, ______ and ________ | the tube body part IR |
| Single most important factor controlling size distortion? | OID |
| The use of a grid prevents much scattered radiation fog from reaching the radiograph, but its use does need an increase in patient _______ | Dose/exposure |
| In fluoroscopy, the larger the input phosphor field size, the ________ patient dose | Less Because larger field size produces little or no magnification of the anatomical areas being evaluated |
| T/F: OID is directly related to spatial resolution | false |
| T/F: SID is directly related to spatial resolution | True |
| The “anode heel effect” results in fewer photons at the _____ and more photons at the _________ | Anode cathode |
| When increasing kilo voltage, radiographic contrast will ________ | decrease |
| what will increase magnification more? a.) 44 in SID to 36 in SID b.)4 in OID | b.4 in OID Because although both increase magnification, it requires an increase of 7 inch in SID to compensate for very inch of OID |
| What term/units is used to express RESOLUTION of a diagnostic image? | Lines pairs per millimeter (lp/mm) |
| T/F: the mAs selection has no impact on scattered radiation production or cleanup | true |
| T/F: Low ratio grids allow a greater percentage of scattered radiation to reach the IR while high ratio grids will clean up a greater amount of scattered radiation before it reaches the IR | Truie |
| Quantum mottle (noise) manifests within an image because __________________ was captured by the image receptor | a poor signal |
| Fast imaging ssytems using ____ mAs and high kV factors are most likely to be the cause of quantum mottle | Low mAs High kVp |
| a graphic diagram of signal values representing various absorption properties within the part being imaged is called a | histogram |
| if SID is too short, a _________ in receptor exposure will occur | increase |
| Phosphors classified as rare earth include____________ | Lanthanum oxybromide Gadolinium oxysulfied |
| the three geometric factors that affect radiographic quality: | Magnification Distortion focal spot blur |
| What is the term when there are unsharp edges on tiny details? | blur |
| T/F:Use of a short SID with a large-size IR causes the anode heel effect to be much more apparent | true |
| increasing grid ratio will result in a larger percentage of scattered radiation being absorbed and hence a ______ scale contrast | Shorter |
| What will improve the spatial resolution of image-intensified images? | -the smaller the input phosphor diameter, the greater the spatal resolution -a very thin coating of cesium iodid on the input phosphor |
| SOD = ____________ | SID - OID |
| The lower the kilo voltage , the __________ is the scale of contrast | Shorter |
| What exposure factors are appropriate for an IVU? | Low kvp (about 70) a higher mA with a short exposre time is generally preferable |
| radiographic contrast is the result of | differential absorption |
| What is LUT? Can it alter contrast? | Look up Table and yes it can |
| When increasing the kilo voltage there will be more high energy photons and there for ______ patient absorption | Less |
| The higher the gid ratio the ____ scatter radiation the grid will clean up,but _____ useful photons will be absorbed as well and the _____ positioning latitude will be allowed | -more -more -less |
| Greater latitude is available to the radiographer using a _____ grid ratio and using ____ kV technical factors | -low -high |
| Radio_______ contrast agents appear white on the finished image becauwse many x-ray photons are absorbed. These are referred to as positive contrast agents with high atomic numbers which absorb xray photons | Radiopaque |
| Radio_______ contrast agents appear black on the finished image becauwse many x-ray photons are not absorbed. These are referred to as negative contrast agents with low atomic numbers . | |
| The _____ the matrix size, the better is the image resolution | Larger |
| ________ represents the image aquisition contrast resolution | bit depth |
| Wide dynamic rage is _____ useful than narrow dynamic range | more |
| Field size is __________ to the exposure rate | Unrelated |
| _______ measures the percentage of X-rays absorbed by the detector | DQU (Detective quantum efficiency) |
| _______ is a method for measuring bone mineral density | DXR (Digital xray radiogarammetry) |
| _______ describes the system’s ability to display signal contrast as a function of spatial resolution | MTF (Modulation Transfer Function) |
| Combinations of milliamperage and expoure time that produce a particular milliampere-seconds value will produce identical receptor exposure. What law is this? | Reciprocity law |
| As SID increases, exposure rate __________ and receptor exposure ___________ | -decreases -decreases |
| What digital imaging characteristic is defined as the “sharpness of the structural edges rocorded in an image”? | spatial resolution |
| what term describes the number of pixels per unit area? | Pixel density |
| removing beam filtartion _____ overall xray energy | Increases |
| _____________ reuslts from an insufficient quantity of xray photons supplied to the IR | Quantum mottle (noise) |
| Short SID’s with larger IR sizes will promote the anode heel effect | True |
| during which examination should 70 kV not be exceeded? | IVU |
| what is the formula to find grid ratio? | Height of lead strips divided by the width of interspace material |
| T/F:Modulation transfer function (MTF) is used to express spatial resolution | TRUE |
| Exposure values arising from excessive kV, insufficient collimation, or thick anatomical structures are termed: | fog |
| If SID is above or below the recommended focusing distance, the primary beam will not coincide with the angled lead strips at the ____________ | lateral edges |
| Why would the pathology atelectasis require an increase in technique? | It makes the area of interest mire difficult to penetrate |
| As SID increases, magnification __________ and spatial resolution ___________ | -decreases -increases |
| the number of xray photons produced (beam intensity/quantity) is controlled by _________ — which has no effect on spatial resolution | mAs |
| Decreased kVp and a ____-ratio grid would allow the least amount of scattered radiation to rach the IR, thereby producing fewer gray tones, thereby having a short scale contrast | high |
| when performing a UGI, the radiographer should use an exposure time of no more than ___ seconds for patients with normal peristaltic motility. and no more than ___ seconds for patients with hypermotility | -0.2 -0.1 |
| To produce just a perceptible increase in receptor exposure in analog imaging, the radiographer should increase the ______ by __% | mAs by 30% |
| The absorption of useful radiation by a grid is called _______ | Grid cutoff |
| The absorption of scattered radiation by a grid before it reaches the IR is called _____ | grid clean up |
| A __________ SNR(signal to noise ratio) prduces higher quality images | Higher Because signal is desirable, noise is not, therefor low SNR severly impairs contrast resolution |
| Spatial resolution is: | the ability to see shapes, outlines, and froms clearly within an image |
| In the digital age spatial resolution is controlled by_______ | pixel size |
| When changing from a single phase to a three phase(both 6 pulse and 12 pulse) equipment, what happens to the original mAs? | only 1/2 of the original mAs would be used |
| ______________ describes the system’s ability to display signal contrast as a function of spatial resolution | Modulation transfer function or MTF |
| _____________ describes the overall efficiency of converting xray signals into useful image | Detective quantum efficiency or DQE |
| _____________ is the range of exposure values that will produce an acceptable image | Exposure latitude |
| __________ determines the gray scale available for the image | Dynamic range |
| The effect that differential absorption has on radioraphc contrast of a high-subject-contrast part can be minimized by: | -using a compensating filter -using high kV factors |
| As the quantity of scattered radiation increases, receptor exposure _________ | Increases |
| More scattered radiation will be generated within a part if the : (3 factors) | -size of the field is increased -kV is increased -thickness and density of tissue increases |
| The best way to control voluntary motion is __________________ | careful explanation of the procedure |
| The relation ship between spatial resolution and SID is _______ | direct |
| The relationship between spatial resolution and focal spot size is : | inveresly related |
| What factor has the greatest effect on receptor exposure? | SID |
| As SID increases, exposure rate _______ and receptor exposure _______ | -decreases -decreases |
| _______ and ________ are candidates for magnification radiography | -Hairline fractures -Minute blood vessels |
| In magnification radiography, the problem of magnification unsharpness is overcome by using a _____________ | fractional spot size |
| Focal spot blur is caused by the use of a large ________ | focal spot |
| Shape distortion (foreshortening, or elongation) is caused by: | improper alignment of the tube, part, and IR |
| size distortionn or magnification, is caused by: | -too great OID -too short SID |
| Beam restrictor is another term for | collimator |
| Focal spot size has an impact on imgae geometry and spatial resolution but has no effect on ______________ | scattered radiation |
| in which of the following examinations woula a IR front with very low absorption properties be especially desirable ? | Mammography |
| Bakelite has long been used at the material for table tops and IR fronts, but now has been replaced largely by ___________ and _____________. | -magnesium -carbon fiber |
| If an image is darker it is said to have ________er receptor exposure | greater |
| As SID increases, exposure rate ______ and radiographic receptor exposure _______ | -decreases -decreases |
| ____________ occurs when an xray photon interacts with matter and disappears, as in the ____________ effect | Absorption; Photoelectric |
| __________ occurs when there is a partial transfer of energy to matter, as in the __________ effect | Scattering; Compton |
| The most intense portion of the beam (the ______ end) should be directed over the thickest part of the anatomy | Cathode |
| In amorphous selenium flat-panel detectors, the term amorphous refers to a : | crystalline material lacking typical crystalline structure |
| Which technique is used to evaluate the dynamics (motion) of a part? | Fluoroscopy |
Created by:
daniel.velazco004