Lec 13 - CT/MRI Imaging

Question 1

cone beam ct does not have nearly as much exposure as blank

Answer 1

medical ct

Question 2

ct advantage is that it is a blank of information and NOT a standard blank

Answer 2

slice, shadow image

Question 3

ct scans are often called CAT scans because it stands for blank

Answer 3

computed axial tomography

Question 4

the geometry for Hounsfield’s original ct scanner used a blank beam

Answer 4

pencil

Question 5

hounsfield found that a 2 or 3 dimensional object could be reproduced from a blank set of projections

Answer 5

infinite

Question 6

blank from tomographic imaging are converted to 2D pixels so that data can be reconstructed into digital images

Answer 6

3D voxels

Question 7

ct number shade of gray that is +1000

Answer 7

dense bone

Question 8

ct number shade of gray that is 0

Answer 8

water

Question 9

ct number shade of gray that is -1000

Answer 9

air

Question 10

newer ct units have a ct number up to blank

Answer 10

+3000

Question 11

spatial resolution is related to blank

Answer 11

pixel size

Question 12

contrast resolution is related to blank

Answer 12

bit depth

Question 13

high threshold will make everything look blank

Answer 13

black

Question 14

3rd generation of ct design had x ray tube and detector moving on blank

Answer 14

different tracks

Question 15

4th generation of ct design has blank moving but there was a stationary continuous ring of blank

Answer 15

x ray tube, detectors

Question 16

to reduce effects of compton scattering in medical ct… each detector has blank… this is also important for control of blank

Answer 16

its own collimator, voxel length

Question 17

artifacts in cone beam ct are from streaks from blank

Answer 17

high density materials like implants

Question 18

3 types of tomography

Answer 18

mri, ct, pet

Question 19

most common mri target

Answer 19

hydrogen nuclei

Question 20

mri is best for blank

Answer 20

soft tissues

Question 21

mri radio frequency pulse leads to blank

Answer 21

disalignment

Question 22

mri recovery rates differ depending on the

Answer 22

tissue type

Question 23

the protons are not perfectly aligned with the magnetic field and instead are blank (wobbling) which results in a blank frequency

Answer 23

precessing, resonant

Question 24

weighted image that looks at fat and makes it bright

Answer 24

t1

Question 25

weighted image that looks at water and makes it bright

Answer 25

t2

Question 26

t1 has fat with the blank t1 relaxation time

Answer 26

shortest

Question 27

t2 has water with the blank t2 relaxation time

Answer 27

longest

Question 28

PET scans… when labeled molecules are metabolized, blank are released which produce blank

Answer 28

positrons, gamma rays

Question 29

imaging of the salivary or ductal system that usually uses iodine

Answer 29

sialography

Question 30

stone in salivary gland

Answer 30

sialolith

Question 31

imaging that uses sound waves and is harmless

Answer 31

ultrasound

Question 32

sound is not part of the blank spectrum

Answer 32

electromagnetic

Question 33

ultrasound imaging uses blank MHz

Answer 33

2-15

Question 34

sound travels blank in solids than in liquids or gas

Answer 34

faster