Help
Options
Question
What is each small region in the grid?
click to flip
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't know
Question
What is a grid of pixels called?
Remaining cards (40)
Know
retry
shuffle
restart
0:02
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
CT Review 3
Image Formation/Processing/Display
| Question | Answer |
|---|---|
| What is each small region in the grid? | pixel |
| What is a grid of pixels called? | matrix |
| how do you determine the number of pixels in a matrix? | rows x columns (matrix size) |
| What is used to assign values to the pixels? | gray scale |
| What is the range of the gray scale? | -1000 to +1000 |
| What coordinates does a pixel use? | X and Y |
| What coordinates does a voxel use? | X,Y, and Z |
| How is a voxel different than a pixel? | it is 3D and has volume |
| What is scan FOV? | the entire area used to collect data for a given body part |
| What is display FOV? | the size of the reconstructed image in the matrix |
| Which can be changed: scan FOV or display FOV? | display FOV |
| Attenuation coefficient depends on what? | 1.photon energy 2.atomic # of tissue 3.thickness of tissue 4.electron density |
| What is one photon sampling? | ray |
| What is one sample location from the pt body? | projection/view |
| What is the hounsfield units of Air? | -1000 |
| What is the hounsfield units of Lung | -500 to -200 |
| What is the hounsfield units of fat? | -200 to -50 |
| What is the hounsfield units of water? | 0 |
| What is the hounsfield units of blood? | 25 |
| What is the hounsfield units of muscle? | 25 to 40 |
| What is the hounsfield units of bone? | 200 to 1000 |
| What is window width? | range of CT #s to be displayed in a image, contrast of the image |
| What is window level? | brightness of image/tissue |
| What is interpolation process? | used to divide data into slices at any arbitrary position |
| What is the thickness at pitch of 1? | collimation is equal to slice thickness |
| What is the thickness at pitch of 2? | slice thickness is 30% greater |
| A pitch of 1.5 is a: | 1.faster scan 2.less samples 3.less available mAs |
| A pitch of .75 is a: | 1.slower scan 2.more samples 3.more available mAs (more radiation) |
| What is Cine? | viewing in rapid sequence |
| What is MIP (maximum intensity) commonly used for? | CTA |
| What is convolution? | process of applying filtration |
| What are the filters used in image recon? | 1.sharp 2.smooth |
| What are sharp filters used for? | musculoskeletal |
| What are smooth filters used for? | abdomen |
| What views do scout images use? | AP, PA, Lateral |
| What are some characteristics of scout images? | large FOV, single projection, tissue superimposed |
| What are the different scanning methods? | 1.scout 2.conventional/serial scan 3.helical/spiral/volumetric scan |
| What is the process of conventional/serial scanning? | scan-stop-move |
| What is the process MPRs (multi planer recon) use? | image-raw data-image |
| What are the 2 steps of image recon? | 1.apply filter to raw data (convolution) 2.apply back projection or cone beam to raw data |
| What are commonly used matrix? | 128x128,256x256,512x512,1024x1024 |
Created by:
Chrslarsen
Popular Radiology sets