Medical Imaging Flashcards
1
Q
Briefly explain how X-ray imaging works.
A
- Uses ionising radiation.
- Emitter > Patient > Detector
- Best for bones / use with contrast media
2
Q
State the advantages and disadvantages of X-Ray imaging.
A
Advantages
- Cheap
- Fast
- Good attenuation bone
Disadvantages
- 2D image
- Poor attenuation soft tissues
- Ionising radiation
3
Q
Briefly explain how CT Scanning works and its uses.
A
Computerised Tomography
- High dose ionising radiation
- Series of X-rays taken in spiral
- Emitter and detectors spin around patient
- 3D image constructed
- Head, Abdomen, Pelvis
4
Q
State advantages and disadvantages of CT imaging.
A
Advantages
- 3D image
- Fast
- Cheap
Disadvantages
- High dose ionising radiation
- Poor attenuation soft tissues
5
Q
Briefly explain how PET scanning works and its uses.
A
Positron Emission Tomography
- Nuclear medicine
- Radioactively tagged glucose injected
- Scan shows metabolically active tissue
(high glucose uptake) - Cancer cells / brain
- Combine with CT scan for 3D view
6
Q
Briefly explain how MRI imaging works.
A
- Huge magnet causes H+ ions to orientate spins half up and half down
- Some unmatched ions point same way
- Radio frequency pulse applied
- Energy to unmatched pairs > flip other way
- Ions returning to original spin state release energy
- Energy detected and turned into image
- Difference between tissue = diff energy emitted
7
Q
State advantages and disadvantages of MRI
A
Advantages:
- High detail
- Great for soft tissues
- No radiation
Disadvantages:
- Expensive
- Slow
- Contraindications (metal implants)
- Noisy / Claustrophobic
- No good for bones / dense tissue
8
Q
Briefly explain how ultrasound imaging works and clinical uses.
A
- Uses sound waves from piezoelectric crystal
- Electrical impulse lets crystal generate sound wave
- Sound wave into tissue
- Transmitter is also receptor (piezoelectric crystal)
- Sound waves reflect back off tissue planes (density changes)
- Reflections detected + turned into image
Uses:
- Foetal scan
- Doppler - blood flow
9
Q
State advantages and disadvantages of ultrasound scanning
A
Advantages:
- No radiation
- Fast / portable
- Cheap
Disadvantages:
- Poor detail
- User dependent
- 2D image
- Bad for high density tissues (bone)
High res = low depth
Low res = high depth
10
Q
Briefly explain fluoroscopy and its uses.
A
- X-ray movie
- Series of x-rays taken in sequence
- Used with contrast
- Shows dynamic flow through system
- Blood flow through vessels
- Swallowing / GI Tract
