L44. Radiology: CT Scans Flashcards
How does computer tomography work?
A cathode ray tube passes through the tissues to a radiation detector that detects gas ionisation and converts it into a digital image
What is computed tomography?
It is a three dimensional, computed image that provides a cross sectional view
Give an analogy of how CT scans are taken and how the images are put together
It is analogous to a slinky with the detector spiralling around the body taking slices of images that are then digitally put together
What can post scanning processing achieve?
Can cut the image into any type of section
What are hounsfield unit?
A digital grey scale that measures the amount of xray attenuation. Most biological tissues lie within -100 to +100
Compare and contrast the spatial resolution, contrast resolution between X-rays and CT scans
X-ray has far better spatial resolution
CT has better contrast
What advantage does having contrast resolution have for CT?
Better ability to differentiate between soft tissues
What are the conventions for orientation of axial, coronal and
sagittal views for CT Imaging
Axial: from the feet up
Coronal: from the front
Sagittal: from the left
Is it necessary to describe the sections of the heart (as per X-rays)?
No because the fissures can be seen
What is a major disadvantage of CT imaging?
High dosage of ionising radiation
Expensive
