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Radiation Therapy Physics 2 > Imaging Modalities > Flashcards

Imaging Modalities Flashcards

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1
Q

5 imaging techniques:

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

Radiographic film and digital imaging are types of ___.

A

plane radiography

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3
Q

Film has 2 important layers:

A

base and emulsion

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4
Q

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

A

structure, image occurs

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5
Q

What does radiographic film do?

A

converts x-rays to image

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6
Q

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

A

more

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7
Q

Crystals in gelatin in emulsion layer are made of?

A

silver halide

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8
Q

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

A

intensifying screen

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9
Q

excited state returns to normal state & releases light photon

A

phosphor luminescence

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10
Q

Other radiographic film:

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

2. single, low

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11
Q

2 types of digital imaging:

A
  1. computed radiography

2. digital radiography

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12
Q

(Similar to screen film radiography)

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

A

Computed, 1

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13
Q

Photostimulable luminescence โ€“ PSL

PSP โ€“ Photostimulable phosphor โ€“ emit light when exposed to different light source is ____ radiography.

A

Computed

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14
Q

Advantages of digital radiography: (3)

A
  1. Higher sensitivity to radiation
  2. Wider dynamic range
  3. Image post-processing
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15
Q

Disadvantage of digital radiography:

A

Spatial resolution depends on pixel size

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16
Q

What is backprojection in CT?

A

Takes each image and combine them into 1

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17
Q

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

A

Pencil
Translate/rotate
1

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18
Q 
2nd gen CT:
\_\_\_ beam
\_\_\_/\_\_\_\_
# of detector(s)
filter?
A

Fan
Translate/rotate
Many detectors
bowtie

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19
Q 
3rd gen CT:
\_\_\_ beam
\_\_\_/rotate
# of detector(s)
artifact?
A

fan
rotate/rotate
Many detectors
ring artifact

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20
Q

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

A

fan
rotate/statinary
many detectors

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21
Q

Helical is __ gen CT, has ___ technology.

A

4th, slip ring

22
Q

gantry rotates, table moves (superior โ€“ inferior)

A

Helical CT

23
Q

Pitch equation:

A

๐‘ƒ= (๐‘๐‘œ๐‘ข๐‘โ„Ž ๐‘‘๐‘–๐‘ ๐‘ก๐‘Ž๐‘›๐‘๐‘’ ๐‘๐‘’๐‘Ÿ ๐‘Ÿ๐‘œ๐‘ก๐‘Ž๐‘ก๐‘–๐‘œ๐‘›)/(๐‘๐‘’๐‘Ž๐‘š ๐‘ค๐‘–๐‘‘๐‘กโ„Ž)

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

24
Q

Pitch:

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

A

contiguous
overlap
gap

25
Q

CT:

calculate the images is ___

A

image reconstruciton

26
Q

CT:

diameter of image reconstruction is ___

A

FOV

27
Q

CT:

physical size of โ€œholeโ€ in the donut is ___

A

Compare aperture size

28
Q

CT:

intensity value of the pixel is ___ AKA ___

A

CT #, Hounsfeld Units

29
Q

CT # equation:

A

K(mtissue - mwater/mwater)

30
Q

3 advantages to radiographic film:

A
  1. easy process
  2. permanent record
  3. established techniques
31
Q

5 disadvantages to radiographic film:

A
  1. chemicals
  2. time
  3. higher dose to pt
  4. dark room
  5. no post-image processing
32
Q

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

A

Nuclear MR

33
Q

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

A

directly

34
Q

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

A

odd

- hydrogen

35
Q

3 MRI components:

A
  1. Primary magnet
  2. Gradient coils
  3. RF coil
36
Q

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

A

uniform, aligns

- B0

37
Q 
MRI:
Protons \_\_\_ (wobble)
A

precess

38
Q

MRI:

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

A

change, determines

39
Q

MRI:
Step 1: The RF coil sends the ___.
Step 2: p+ flips to __ energy state.
Step 3: p+ precess โ€œ___ phaseโ€

A
  1. RF pulse
  2. high
  3. in
40
Q

MRI:

____ produce linear variation in field along z-axis.

A

Gradient coils

41
Q

Which type of imaging is this?

  • Functional assessment of tissue
  • Measures Metabolic activity
A

PET

42
Q

Which type of imaging is this?

- Uses FDG

A

PET

43
Q

Does FDG have a long or short half=life?

A

short

44
Q

Which type of imaging is this?

- Functional info but little anatomic detail

A

PET

45
Q

Process of PET scan:

Radionuclide is injected. Radionuclide travels to places of ___ metabolic activity.

A

increased

46
Q

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.

A

electron, 511 keV, opposite, 180-degrees

47
Q

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

A

BAT

48
Q

Disadvantages of ultrasound: (2)

A
  1. user subjectivity - quality depends on tech

2. doesnโ€™t penetrate air/bone

49
Q

CT Imaging - kv vs. MV:

kV: ___ contrast and ___ dose

A

higher contrast and lower dose

50
Q

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

A

Soft, Adaptive

Radiation Therapy Physics 2 (9 decks)

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