Imaging Modalities

Question 1

5 imaging techniques:

Answer 1

1. plane radiography
2. CT
3. MRI
4. PET
5. Sonography

Question 2

Radiographic film and digital imaging are types of ___.

Answer 2

plane radiography

Question 3

Film has 2 important layers:

Answer 3

base and emulsion

Question 4

Base provides ___ and the emulsion layer is where the ___.

Answer 4

structure, image occurs

Question 5

What does radiographic film do?

Answer 5

converts x-rays to image

Question 6

Higher the Z of the tissue, the ___ the probability of interaction.

Answer 6

more

Question 7

Crystals in gelatin in emulsion layer are made of?

Answer 7

silver halide

Question 8

amplifies effect of x-rays that reach the screen (film sensitive to light)

Answer 8

intensifying screen

Question 9

excited state returns to normal state & releases light photon

Answer 9

phosphor luminescence

Question 10

Other radiographic film:

1. direct exposure, which has a __ dose and has __ blurring
2. mammography, which is ___ emulsion and has a __ dose

Answer 10

1. high, less

2. single, low

Question 11

2 types of digital imaging:

Answer 11

1. computed radiography

2. digital radiography

Question 12

(Similar to screen film radiography)

X-ray interaction is trapped electrons in a higher energy metastable state is ____ radiography. What stage?

Answer 12

Computed, 1

Question 13

Photostimulable luminescence – PSL

PSP – Photostimulable phosphor – emit light when exposed to different light source is ____ radiography.

Answer 13

Computed

Question 14

Advantages of digital radiography: (3)

Answer 14

1. Higher sensitivity to radiation
2. Wider dynamic range
3. Image post-processing

Question 15

Disadvantage of digital radiography:

Answer 15

Spatial resolution depends on pixel size

Question 16

What is backprojection in CT?

Answer 16

Takes each image and combine them into 1

Question 17

1st gen CT:
___ beam
___/____
# of detector(s)

Answer 17

Pencil
Translate/rotate
1

Question 18

2nd gen CT:
\_\_\_ beam
\_\_\_/\_\_\_\_
# of detector(s)
filter?

Answer 18

Fan
Translate/rotate
Many detectors
bowtie

Question 19

3rd gen CT:
\_\_\_ beam
\_\_\_/rotate
# of detector(s)
artifact?

Answer 19

fan
rotate/rotate
Many detectors
ring artifact

Question 20

4th gen CT:
___ beam
___/___
# of detector(s)

Answer 20

fan
rotate/statinary
many detectors

Question 21

Helical is __ gen CT, has ___ technology.

Answer 21

4th, slip ring

Question 22

gantry rotates, table moves (superior – inferior)

Answer 22

Helical CT

Question 23

Pitch equation:

Answer 23

𝑃= (𝑐𝑜𝑢𝑐ℎ 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑝𝑒𝑟 𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛)/(𝑏𝑒𝑎𝑚 𝑤𝑖𝑑𝑡ℎ)

Cats, Dogs, Parrots, and Rottweilers do Bad in the Wild

Question 24

Pitch:

1: 1 is ___
0. 5:1 is ___
2: 1 ___

Answer 24

contiguous
overlap
gap

Question 25

CT: | calculate the images is ___

Answer 25

image reconstruciton

Question 26

CT: | diameter of image reconstruction is ___

Answer 26

FOV

Question 27

CT: | physical size of “hole” in the donut is ___

Answer 27

Compare aperture size

Question 28

CT: | intensity value of the pixel is ___ AKA ___

Answer 28

CT #, Hounsfeld Units

Question 29

CT # equation:

Answer 29

K(mtissue - mwater/mwater)

Question 30

3 advantages to radiographic film:

Answer 30

1. easy process 2. permanent record 3. established techniques

Question 31

5 disadvantages to radiographic film:

Answer 31

1. chemicals 2. time 3. higher dose to pt 4. dark room 5. no post-image processing

Question 32

nuclei in a magnetic field will absorb and re-emit electromagnetic radiation

Answer 32

Nuclear MR

Question 33

In MRI, resonant frequency of material is ____ proportional to the magnetic field strength applied

Answer 33

directly

Question 34

In MRI, tissue must have ___ number of protons or neutrons (have net angular momentum). - ___ is most abundant p+ in body

Answer 34

odd | - hydrogen

Question 35

3 MRI components:

Answer 35

1. Primary magnet 2. Gradient coils 3. RF coil

Question 36

MRI: The primary magnet has a strong, ___ magnetic field and ___ protons. - protons align w/___

Answer 36

uniform, aligns | - B0

Question 37

``` MRI: Protons ___ (wobble) ```

Answer 37

precess

Question 38

MRI: | The gradient coils ___ primary field strength and ___ part of body to be imaged.

Answer 38

change, determines

Question 39

MRI: Step 1: The RF coil sends the ___. Step 2: p+ flips to __ energy state. Step 3: p+ precess "___ phase"

Answer 39

1. RF pulse 2. high 3. in

Question 40

MRI: | ____ produce linear variation in field along z-axis.

Answer 40

Gradient coils

Question 41

Which type of imaging is this? - Functional assessment of tissue - Measures Metabolic activity

Answer 41

PET

Question 42

Which type of imaging is this? | - Uses FDG

Answer 42

PET

Question 43

Does FDG have a long or short half=life?

Answer 43

short

Question 44

Which type of imaging is this? | - Functional info but little anatomic detail

Answer 44

PET

Question 45

Process of PET scan: | Radionuclide is injected. Radionuclide travels to places of ___ metabolic activity.

Answer 45

increased

Question 46

Process of PET scan: Positron-emitting radionuclide is injected. Emitted positron finds an ___ and collides with it, creating annihilation and 2 gamma rays of ___ (energy) go in ___ directions. Detectors detect the radiation. It is considered a true coincidence if two detectors ___ apart detect gamma rays at the same time.

Answer 46

electron, 511 keV, opposite, 180-degrees

Question 47

___ is a type of ultrasound that used ot be used in RT for prostate.

Answer 47

BAT

Question 48

Disadvantages of ultrasound: (2)

Answer 48

1. user subjectivity - quality depends on tech | 2. doesn't penetrate air/bone

Question 49

CT Imaging - kv vs. MV: | kV: ___ contrast and ___ dose

Answer 49

higher contrast and lower dose

Question 50

MR Linac: ___ tissue imaging during radiation therapy ___ treatment delivery in real-time

Answer 50

Soft, Adaptive