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
Image Production
Review
| Question | Answer |
|---|---|
| Three visibility factors: | Intensity • Contrast • Noise |
| Maximum visibility occurs when | Maximum visibility occurs when |
| The term density is primarily reserved for film based images. • Defined as the "overall darkness of an image." • Measured by a device called a densitometer. | Optical Density |
| Opposite of density, but conveys the same overall concept. • Term that is reserved for the digital age of imaging. | Brightness |
| Digital images can also be presented in two different fashions. | negative and positive |
| Most radiographs are presented as | a negative image. |
| High variation of black and white: | High Contrast • Short Scale |
| Low variation of black and white (many grays): | Low Contrast • Long Scale |
| When gray scale is not correctly produced, | changes in brightness levels WILL NOT correct for it |
| Excessive contrast causes | Loss of useful information, or loss of details in image. |
| An increase in mAs would _____ the _____ of the emission spectrum. | Increase Amplitude |
| A 15% increase in kVp is equivalent to ____ | Doubling the mAs |
| Because of differential absorption, about _____% of the incident beam from the x-ray tube contributes to the finished image. | 0.5% |
| Image fog in diagnostic imaging is caused by | Compton scatter |
| Approximately ___ of kinetic energy of projectile electrons is converted to x rays at the target. | Less than 1% |
| The efficiency of x-ray production increases as _____ increases. | KVP |
| Some DR units have as many as ____ AEC units instead of 3 | 5 |
| THe two main advantages of DR are its | High compatiblity with PACS systems and increased departmental efficiency |
| DR operates at a consistent ____ for all procedures, so techs ar Elmore confident when setting manual techniques and have less tendency to use higher technique than they think necessary | "Speed class" |
| Portable DR unites might be considered to be "directly connected" to the unit ______ because it uses radio waves to immediately send exposure info to the unit where it is displayed within a few seconds | electromagnetically |
| What are DELs? | Detector elements |
| TFT detectors are flat and extremely thin, which allows | An entire array to be assembled into a panel thin enough for use as a "portable" plate for mobile radiography called flare panel technology |
| What are the 3 components of a del | Semiconductor detection surface Microscopic capacitor TFT (thin film transistor for a switch) |
| The percentage of the square devoted to the semiconductor detection layer is called the dels ____ | fill factor |
| Input phosphor sizes can come in these sizes | 6, 9, 12 or 16 inches in diameter. |
| ANGLES GREATER THAN 15 DEGREES | REQUIRE COMPENSATION IN TECHNIQUE (DUE TO EFFECT ON DISTANCE) |
| What are CPGs | Constant Potential Generators. They are battery powered. Must keep batteries charged between uses, or needed radiographic technique may no the available. High voltage efficiency- almost no ripple effect. |
| The Output Phosphor is made of what? | cesium iodide |
| Concentrating the electrons increases output intensity is termed | Minification |
| the photocathode is made of | A thin photoemissive metal layer, made of a combination of antimony and cesium compounds |
| What are the different types of distortion? | Pincushion beiling glare and vignetting |
| How does magnification work? | By changing the electric charge on the electrostatic lenses to bring the focal point of the electron beam closer to the input phosphor |
| Larger number of pixels in an image matrix can only be accommodated by using | smaller pixels, which enhances sharpness. |
| What are the five basic parts to the i.i? | input phosphor photocathode electrostatic lenses accelerating anode output phosphor |
| The backup time should be set | above the expected exposure time |
| Which one of these would be the best for a radiographer to do to control motion when using automatic exposure control | Use high mA |
| What change will produce a radiograph with higher contrast when using AEC | decrease the kVp |
| If a low mA is selected the automatic exposure control will | use a long exposure time |
| If the center photocell is used instead of the two outside photocells for a PA chest exposure | The radiograph will be too dark |
| Scatter happens because of | some projectile electrons striking the focal spot and scattering from anode and they strike other things |
| Off focus x rays are still apart of the | Primary Beam |
| It is not uncommon for the light field to be projected | as much as one half inch off the actual x ray beam |
| Production of good subject contrast in the remnant beam is dependent upon | the proportions of different interactions within the patient relative to each other |
| The smaller the collimated field size, the | higher the subject contrast present in the remnant beam |
| Concentration of primary X ray remains _____ regardless of field size | the same |
| Field size limitation has nothing to do with the | SHARPNESS OF DETAIS WIHIN THE IMAGE FIELD!! (distortion, magnification) |
| Sensors in the bucky tray detect the size of cassette plate and send an electronic signal to activate small motors in the collimator to adjust to the shutters to size of IR is termed | Positive beam limitation (PBL) |
| An image with excessive scatter radiation present in it can be _____ at the same time | Underexposed |
| What are the three factors that increase the amount of scatter radiation produced? | 1. High levels of kVp 2. Large field sizes 3. Large body part thicknesses of soft tissues |
| Photoelectric interactions are rapidly ____ at higher kVps | lost |
| Number one factor of scatter | field size |
Created by:
cdprice
Popular Standardized Tests sets