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
MARIANNE EXAM 3
Quality Management Created by Krystal
| Question | Answer |
|---|---|
| What affect does an increase in filtration have on Density and Contrast? | density - decreases density because it eliminates quantity(mA) of beam used contrast - lower contrast as leaves with higher kVp |
| An increase in SID(from 40" -> 72") will have what affecton Density and Contrast? | decrease density and have no effect on contrast |
| What affect does increasing the grid ratio have on Contrast and density? | increase the contrast and decrease the density( High grid ratio= higher contrast) |
| What affect does increasing the OID have on Density and Contrast? | decrease density and increase the contrast. |
| If you Increase kVp what will happen to Contrast?...Density? | decrease contrast and increase density |
| If you increase beam restriction what will happen to Density? ...Contrast? | increase contrast and decrease density |
| mAs controls what? | Density |
| If you increase mAs what happens to Contrast?...Density? | No affect on Contrast, and increase in density |
| A 15% increase in kVp does what to density? | doubles the density. (This is why when we use the 15% rule we either halve or double the mAs to MAINTAIN the same density on our image |
| An increase in SID ( from 40"-> 72") will have what affect on Detail?....Distortion? | increase the detail which in turn will decrease distortion |
| An increase in Focal Spot Size (from a small to a large) will have what affect on Detail?...Distortion? | decrease the detail and has no affect on distortion. |
| An increase in motion will have what affect on detail?.....distortion? | decrease the detail cause it'll look blurry and increase the distortion |
| An increase in OID will have what affect on Detail?...Distortion? | decrease detail and increase distortion ( the closer you have the object to the IR the better detail) |
| Define Radiographic Quality | refers to the fidelity with which the anatomical structure that is being examined is imaged on the radiograph. A image that faithfully reproduces structure and tissue is identified as a high-quality radiograph |
| Define Spatial Resolution | refers to the ability to image small objects that have high subject contrast such as a bone-soft tissue interface, a breast micro calcification or a calcified lung nodule |
| Define Contrast resolution | is the ability to distinguish anatomical structures of similiar subject contrast such as liver-spleen and gray matter-white matter. |
| Define Noise | Radiographic noise is the random fluctuation in the optical density of the image |
| Define Quantum Mottle | refers to the random nature by which x-rays interect with the IR. When few x-rays are cast at the IR, the resulting image appears mottled or blotchy. |
| Define the Characteristic Curve | The relationship between OD and radiation exposure create the curve. Need an optical step wedge(sensitometer) and a densitometer to create this |
| Define magnification | when an image on the radiograph is larger then the object they represent. |
| How can you minimize magnification? | Use the largest SID and the smallest OID |
| Define Distortion | unequal magnification of different portions of the same object. |
| Distortion depend on......? | 1. Object thickness 2. object position 3. object shape |
| Define Focal spot blur | A blurred region on the radiograph over which the rad tech has little control. Occurs because the focal spot is not a point. |
| Focal spot blur is greatest on which side?.... Cathode or Anode? | Greater on the cathode side |
| How can you minimize focal spot blur? | Use small focal spot and position patient so that part is close to IR. SID's are usually fixed already but use as far as possible. |
| Define Heel effect | varying intensity across the x ray field in the anode-cathode direction |
| Factors effecting subject contrast | patient thickness, tissue mass density, effective atomic #, object shape, kilovolt peak |
| Define Motion Blur | movement of the patient or the x ray tube during exposure results in blurring of the image |
| Define Sensitometry | the study of the relationship between the intensity of exposure of the film and the blackness after processing is called this |
| Sharpness of image detail is best measured by.....? | Spatial resolution |
| The visibility of image detail is best demonstrated by.....? | Contrast resolution |
| Define foreshortening | means that the anatomical part appears smaller than normal |
| Define elongation | means that the anatomical part of interest appears bigger than normal |
| Visibility of image detail | describes the ability to see the detail on the radiograph and is best measured by contrast resolution |
| How does Latitude affect the Characteristic Curve? | If you have a Narrow latitude(short scale, hign contrast)you have a steep slope. If you have a Wide latitude you'll have a long slope with long scale and low contrast.With wider latitude mAs can vary and still produce good image. |
| Procedures for reducing motion blur? | Use shortest exposure time, provide good communication or using restraining device. Use a Large SID, and Small OID |
| How does phototimer work? | Its a device that allows AEC. It senses the amount of radiation incident on the IR, through electric feedback circuit, radiation exposure is terminated when sufficient # of x-rays has reached IR to produce an acceptable optical density |
| Base plus fog optical density has a range of approx? | 0.1 to 0.03 |
| The straight line portion of a characteristic curve represents..... | the region in which a properly exposed radiograph appears. Its the diagnostic range. |
| How can you reduce quantum mottle? | use high mAs and low kVp setting, slower IR |
| What are the principal exposure technique factors? | kVp, ma x s or mAs, and SID |
| With AEC, explain how the exposure could terminate early? | the cells cannot tell the difference between the primary beam and the scattered radiation, so if a high proportion of scatter radiation reachs cells, exposure is terminated prematurly |
| How can you reduce magnification? | Large SID, shortest OID |
| The useful reange of OD is approx? | 0.25 to 2.5 |
| Fast IR's have_____ noise and what does it do to spatial resolution and contrast resolution? | they have high noise and low spatial resolution and low contrast resolution |
| High spatial resolution and contrast resolution require____noise and __________ IR's | low noise and slow IR's |
| Focal spot does not affect...... it only affects...... | Focal spot does NOT affect contrast or density, it affect recorded detail and focal spot blur. |
| Distortion can be reduced by...... | positioning the anatomiacal part of interest in a plane parallel to that of the IR |
| Increased Pt thickness does what to contrast and density? | Decreased Contrast(cause more scatter) and Density...Has a indirect relationship with both |
| Increase grid ratio...what happens to contrast and density? | Increased contrast and decreased density. (Higher grid ratio=higher contrast cause more lead strips absorbing more scatter so image with be more black and white) |
| Increased compression has what affect on contrast, density, detail and distortion? | Nothing on Density, Increased contrast cause less scatter, also increased detail and no effect on distortion. |
Created by:
mcc radiology
Popular Radiology sets