11. CBCT

Question 1

4

What is the shape of the x-ray beam for CBCT?

Question 2

4

A CBCT is the only _____ scan enough to acquire a full volume of images

Question 3

4

What is the scan time for CBCTs?

Question 4

5

Raw CBCT images are slightly offset ____ images.

Question 5

5

Reconstruction algorithms:

Filtered back projection with _____ reconstruction used to produce _____.

Question 6

6

What is the difference between CBCT and MDCT?

Question 7

7

What are the three components of CBCT?

Question 8

8

What are the two types of x-ray generation for CBCT?

Question 9

8

Is continuous or pulse x-ray generation preferred? Why?

Question 10

8

What factor is used to determine mA and kVp for CBCT?

Question 11

8

Faster CBCt scans = _____ radiation exposure but ____ noise.

Question 12

8

Slower CBCT scans = ____ basis images = ____ radiation exposure = better images

Question 13

8

When generating a CBCT, limit the field size to the ______.

Question 14

8

What is the rotation angle range for CBCTs?

Question 15

8

What is the relationship etween rotation angle, radiation exposure, and noise?

Question 16

9

What are two ways to detect x-rays?

Question 17

9

What is the most common x-ray detector for CBCT?

Question 18

10

What is the smallest element of a digital picture?

Question 19

10

A pixel is synonymous to a ____ in a detector.

Question 20

10

Pixels are arranged in rows and columns to form the ____.

Question 21

11

What is the term for a 3D representation of a pixel?

Question 22

11

What shape is a voxel in CBCT?

Question 23

11

What term relates to the ability of an image to reveal fine detail?

Question 24

11

What is the principal determinant of voxel size in a CBCT?

Question 25

11 What is the relationship between pixel size and resolution?

Question 26

11 What is a disadvantage of having a small pixel/voxel?

Question 27

12 What is the term for the number of gray shades that can be displayed?

Question 28

12 What is the number for the currently available gray shades for CBCT?

Question 29

12 What effect does higher bit depth have on computational time and file sizes?

Question 30

14 Describe the ideal size of the scan volume or field of view.

Question 31

18 How many reformatting steps are done once the CBCT machine is run?

Question 32

19 Were is the primary reconstruction of a CBCT done?

Question 33

19 Where is the secondary reconstruction done?

Question 34

24 What is a ray sum? What are two types of projections it can generate?

Question 35

25 What does volume rendering visualization of?

Question 36

26 What are inherent artifacts a result of?

Question 37

26 What are procedure-related artifacts and what do they lead to?

Question 38

26 What produces introduced artifacts?

Question 39

26 What kind of artifacts do these three things produce: -Scatter -Partial volume averaging -Cone-beam effect

Question 40

26 What artifact do these things produce: -Aliasing artifact -Scanner related artifact -Double contour artifact

Question 41

26 What artifact do these result in: -beam hardening: cupping artifact; extinction or missing artifact -patient motion

Question 42

28 What is a partial volume average inherent artifact?

Question 43

30 What is an Aliasing Artifact?

Question 44

31 What is a scanner related artifact?

Question 45

32 What causes a double contour artifact?

Question 46

33 What are beam hardening artifacts?

Question 47

33 What are the 2 types of beam hardening artifacts?

Question 48

33 What is the beam hardening artifact type where there is distortion of metallic structures as a result of differential absorption?

Question 49

33 What is the beam hardening artifact type when dark bands are present between two dense objects?

Question 50

36 What are three general applications for CBCT?

Question 51

40 Are images distorted in panoramics or CBCTs?

Question 52

40 What views are seen in panormaics?

Question 53

40 What views are seen in CBCT?

Question 54

40 Are structures superimposed in CBCTs and panoramics?

Question 55

40 Does CBCT or panoramic have a higher radiation dose?

Question 56

41 4 Strengths of CBCTs: 1. _____ size compared with conventional CT equipment 2. _____ acquisition 3. ______ resolution 4. relatively ____ patient radiation dose

Question 57

41 2 Cons of CBCTs: 1. ______ 2. ______