symposium 2: imaging Flashcards
In which imaging techniques is ionising radiation used?
- radiography
- CT
- interventional radiology (fluoroscopy)
- nuclear medicine
What can happen to an X-ray beam when passed through matter?
- transmitted
- absorbed
- scattered
Describe what it means when X-rays are transmitted?
pass through unaffected or with lower energy
Describe what it means when X-rays are absorbed?
transfer all energy to matter and not pass through the patient to the film
Describe what it means when X-rays are scattered
diverted with or without energy loss
In the absorption of X-rays, what is the colour from least dense to most dense?
black to bright white
What are the advantages of radiography?
- great spatial resolution
- cheap and available
- easy interpretation
What are the disadvantages of radiography?
- projectional
- ionising radiation
- very limited soft tissue visualisation
What does CT scan stand for?
computed tomography
What are the strengths of computed tomography?
- cross-sectional
- spatial resolution
- widely available
What are the weaknesses of CT scans?
- ionising radiaion
- limited soft tissue contrast
What are the non-ionising imaging methods?
- ultrasound
- MRI
How does ultrasound imaging work?
based on the production and detection of echoes
What is an echo and when does it occur?
- it is a reflection of a beam
- occurs at the interface between two materials
What are the strengths of ultrasound imaging?
- non-ionising
- mutliplanar
- dynamic
- doppler
What weaknesses does ultrasound imaging have?
- operator-dependent
- can’t see through bone or gas
What does MRI stand for?
magnetic resonance imaging
What are the strengths of MRI scans?
- non-ionising
- multiplanar
- exquisite soft tissue contrast
- reproducible
- non-operator dependent
What are the weaknesses of MRI scans?
- limited availability
- magnetic field
- some patients/equipment not suitable
- expensive shielding
- can be difficult to appreciate calcification or gas
What are the 3 conventional planes for imaging?
- axial (transverse)
- coronal (frontal)
- sagittal (lateral)
What is interventional radiology?
image guided diagnostic/therapeutic procedure achieved through percutaneous puncture/body opening
What are the two types of metallic stents?
- balloon expandable
- self-expanding
