Physics question 10
Homework
MPHY 501 Part 1 Lecture 10 Ch 10
Computerized Tomography Part II
1) What motivates the setting of CT scan procedure protocols?
2) Name 10 acquisition/processing parameters that need to be set.
3) What is done so the scanner knows the behavior of the bowtie filter?
4) Given that digital detectors elements have different levels of sensitivity
a. How are they calibrated?
b. When are the calibrated?
5) Where is a reference detector located?
6) Why is a reference detector needed?
7) How is the differences in gain between detectors corrected?
8) What is a projection?
9) What is a forward projection?
10) What is a backprojection?
11) Describe a filtered back projection.
12) Discuss the difference between a bowtie filter and the filter used in filtered backprojection (this should be a thoughtful and potentially lengthy discussion).
13) What kind of Kernels are used in Filtered Backprojection?
a.
b.
c.
d.
e.
14) What is a filter Roll Off
15) What is a filter Roll Off
16) How does a ramp filter exacerbate noise?
17) Why do we say that noise is high frequency data?
18) Using the concept of the slide pictured below show Using a spread sheet how to use an edge enhancement filter with the shift multiply add similar to the RECT smoothing filter in the picture.
19) What do you expect may have happened between image A and image B below to make image Bs contrast so much better?
A) B)
20) In the diagram below:
a. What type of projection is required to recreate the image
b. Fill in the correct for processing values (double click on the orange box to enter value).
c. What would it take to go from for processing values to presentation values?
3
8
15
13
4
15
17
11
15
10
18
7
9
10
12
5
21) How does an iterative algorithm work (again here may require a longer explanation, Do not copy some irrelevant answer from Wikipedia!!!)
22) State 5 factors that affect ultimate resolution in CT
23) What kind of test device is used in CT resolution testing
24) How does a digital filter alter resolution?
25) From 1990 to today:
a. what has the progress in CT resolution been?
b. In what dimension is this resolution?
26) Is quantum limited imaging noise (?):
a. proportional to a constant?
b. If not proportional to a constant then what?
27) In a CT image, outside of the imaged object are areas of background that appear more or less black but are not. In fact those areas are where we take a region of interest to sample the noise background or the noise if the region of interest is square and of 9 pixels like the table below what is the standard deviation of the noise (show your math)?
3
2
7
5
1
9
28
9
7
28) What can happens to the resolution because of iterative reconstruction?
29) What is it called when the resolution is not the same (due to some mechanism that causes blurring) everywhere in an image?
30) What 4 factors affect contrast resolution?
31) Name 5 CT image artifacts
1.
2.
3.
4.
5.
32) How do the artifacts in the above question come about?
6.
7.
8.
9.
10.
33) How do the artifacts in the above question get fixed?
11.
12.
13.
14.
15.
34) Describe a First generation CT
35) Describe a 3rd generation CT
36) Describe a 4th generation CT
37)
a.
b.
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