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1130 # 3
test 3
| Question | Answer |
|---|---|
| What are the two types of information computers use | Analog, digital |
| What is image blurring | Quantum mottle, noise, motion |
| What other terms can be used to explain window width changes | +/-, as width increases, contrast increases |
| When is the IP most sensitive to scatter | Before and after exposure |
| What is filtering | Hardens the beam, amp or deleted unwanted frequency |
| Detectors can detect information from what sources | Cassette bases, cassette less |
| What is a matrix and how does it affect resolution | Series of boxes that gives and image form. Bigger the matrix the better the resolution |
| What is a pixel and how does it affect resolution | Box that makes up matrix, determines the # or gray tone |
| What are thin film transistors | Collect charged products by selenium or silicon on array or matrix pixel sixe detector. |
| Define frequency and explain how it relates to contrast. | |
| How is noise measured and explain it’s effect on contrast and density | random background info, signal noise ratio |
| What does window level control | density +/- |
| What is data clipping | Too much info is send through so the computer chooses what dx info needs to be sent |
| What does window width control | Contrast x division |
| What controls the resolution of the digital image | Pixel size |
| What is masking | |
| Describe high-pass filtering and when it is useful. Take out all but high frequency, increase image quality | |
| How does direct conversion work | |
| What is Fourier Transformation | Convert data into a more useful form |
| How is an IP erased | processor |
| How do detectors acquire information | Through phosphor collectors |
| Name some benefits of the increased latitude of CR. | |
| Why are imaging plates more sensitive to radiation than radiographic film | |
| Describe how a latent image is produced using CR. | |
| How long will a latent image store its energy | 32 hr, looses 23% every 8 hr |
| How does the latitude of CR compare to that of film | Latent image has a wide latitude |
| Define photostiumulated luminescence (PSL). | |
| What color light photons are released when electrons return to a lower energy state | Blue violet |
| What is the difference between object class and service class in DICOM | |
| Describe the difference between cassette-based and cassette-less Systems | |
| Based: psp exposed ad put into reader, less: detector and reader are one | |
| The smaller the pixel, the _____ the spatial resolution | better |
| What is a histogram and why is it generated | Locates min/max signal w/I anatomical region of interest in the image. Provides proper gray scale. |
| What happens if an incorrect histogram / algorithm is selected | Density and contrast are off |
| What kVp is recommended with non-grid imaging and why | Increase scatter |
| Name the layers of photostimulable imaging plates and their functions | Protective, phosphor, conductor, support, light shield, backing |
| What is the language computers operate from | binary |
| What is the difference in the data handled by analog computers and the | |
| data handled by digital computers | AC: continuously varying, DC: definite quantities |
| How does indirect conversion work | Uses PSP |
| What is the great danger that exists with CR and radiation protection | |
| practices | Increase in pt dose beacue of improper tech setting |
| What factors that produce low contrast are prone to cause CR image plate | |
| fogging | Low kVp |
| What is image stitching | Taking multiple images and the computer puts them together as one long image |
| Describe how grids should be used with CR. Long part with long axis. CR in the middle of IT | |
| What is a scintillator and how does it work | changes light to electrical signal |
| What is a charged couple device | converts visible light to x-ray |
| What is the difference between RIS and HIS | R-radiology, H; hospital |
| What are some advantages of using soft-copy display | |
| What affects image quality on a CRT monitor | |
| Why can higher ambient light be used with an LCD | |
| What is edge enhancement | Over print data at edge line |
| Specify three advantages of digital image management in comparison to traditional film/screen environments. | |
| What formula is used to calculate digital image size | Why is this important |
| What is the difference between a LAN and a WAN | How is each used in an imaging department |
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