Imaging Modalities Flashcards
5 imaging techniques:
- plane radiography
- CT
- MRI
- PET
- Sonography
Radiographic film and digital imaging are types of ___.
plane radiography
Film has 2 important layers:
base and emulsion
Base provides ___ and the emulsion layer is where the ___.
structure, image occurs
What does radiographic film do?
converts x-rays to image
Higher the Z of the tissue, the ___ the probability of interaction.
more
Crystals in gelatin in emulsion layer are made of?
silver halide
amplifies effect of x-rays that reach the screen (film sensitive to light)
intensifying screen
excited state returns to normal state & releases light photon
phosphor luminescence
Other radiographic film:
- direct exposure, which has a __ dose and has __ blurring
- mammography, which is ___ emulsion and has a __ dose
- high, less
2. single, low
2 types of digital imaging:
- computed radiography
2. digital radiography
(Similar to screen film radiography)
X-ray interaction is trapped electrons in a higher energy metastable state is ____ radiography. What stage?
Computed, 1
Photostimulable luminescence β PSL
PSP β Photostimulable phosphor β emit light when exposed to different light source is ____ radiography.
Computed
Advantages of digital radiography: (3)
- Higher sensitivity to radiation
- Wider dynamic range
- Image post-processing
Disadvantage of digital radiography:
Spatial resolution depends on pixel size
What is backprojection in CT?
Takes each image and combine them into 1
1st gen CT:
___ beam
___/____
# of detector(s)
Pencil
Translate/rotate
1
2nd gen CT: \_\_\_ beam \_\_\_/\_\_\_\_ # of detector(s) filter?
Fan
Translate/rotate
Many detectors
bowtie
3rd gen CT: \_\_\_ beam \_\_\_/rotate # of detector(s) artifact?
fan
rotate/rotate
Many detectors
ring artifact
4th gen CT:
___ beam
___/___
# of detector(s)
fan
rotate/statinary
many detectors
Helical is __ gen CT, has ___ technology.
4th, slip ring
gantry rotates, table moves (superior β inferior)
Helical CT
Pitch equation:
π= (πππ’πβ πππ π‘ππππ πππ πππ‘ππ‘πππ)/(ππππ π€πππ‘β)
Cats, Dogs, Parrots, and Rottweilers do Bad in the Wild
Pitch:
1: 1 is ___
0. 5:1 is ___
2: 1 ___
contiguous
overlap
gap
CT:
calculate the images is ___
image reconstruciton
CT:
diameter of image reconstruction is ___
FOV
CT:
physical size of βholeβ in the donut is ___
Compare aperture size
CT:
intensity value of the pixel is ___ AKA ___
CT #, Hounsfeld Units
CT # equation:
K(mtissue - mwater/mwater)
3 advantages to radiographic film:
- easy process
- permanent record
- established techniques
5 disadvantages to radiographic film:
- chemicals
- time
- higher dose to pt
- dark room
- no post-image processing
nuclei in a magnetic field will absorb and re-emit electromagnetic radiation
Nuclear MR
In MRI, resonant frequency of material is ____ proportional to the magnetic field strength applied
directly
In MRI, tissue must have ___ number of protons or neutrons (have net angular momentum).
- ___ is most abundant p+ in body
odd
- hydrogen
3 MRI components:
- Primary magnet
- Gradient coils
- RF coil
MRI:
The primary magnet has a strong, ___ magnetic field and ___ protons.
- protons align w/___
uniform, aligns
- B0
MRI: Protons \_\_\_ (wobble)
precess
MRI:
The gradient coils ___ primary field strength and ___ part of body to be imaged.
change, determines
MRI:
Step 1: The RF coil sends the ___.
Step 2: p+ flips to __ energy state.
Step 3: p+ precess β___ phaseβ
- RF pulse
- high
- in
MRI:
____ produce linear variation in field along z-axis.
Gradient coils
Which type of imaging is this?
- Functional assessment of tissue
- Measures Metabolic activity
PET
Which type of imaging is this?
- Uses FDG
PET
Does FDG have a long or short half=life?
short
Which type of imaging is this?
- Functional info but little anatomic detail
PET
Process of PET scan:
Radionuclide is injected. Radionuclide travels to places of ___ metabolic activity.
increased
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.
electron, 511 keV, opposite, 180-degrees
___ is a type of ultrasound that used ot be used in RT for prostate.
BAT
Disadvantages of ultrasound: (2)
- user subjectivity - quality depends on tech
2. doesnβt penetrate air/bone
CT Imaging - kv vs. MV:
kV: ___ contrast and ___ dose
higher contrast and lower dose
MR Linac:
___ tissue imaging during radiation therapy
___ treatment delivery in real-time
Soft, Adaptive
