CT Scans Flashcards
What does CT stand for?
Computed Tomography
Are CT scans 2D or 3D?
3D
Who made the first X-ray, when, and what of?
Röntgen
1895
Of his Wife’s hand.
What is the name of the hole is the CT scanner and how large is it?
Boar
Aperture of 60cm
What is the name of what the patient lies on in a CT scanner?
Couch
What type of shape beam does a CT scanner have?
Fan beam
Does the couch move the patient through the boar of the scanner move around the patient?
Patient positioning table moves through the scanning field (at a constant speed)
kVp of an X-ray tube
120
How long is one revolution of an X-ray tube?
<250ms
What does a CT scanner measure to create an image?
The X-ray attenuation through the object/tissue
Define voxel
Volume element
Values of Water, Air and Bone in Hounsfield Units
Water = 0, Air = -1000, Bone > +400
What colour is bone and air on a CT
Bone is white
Air is black
Name 4 applications of CTs
Coronary CT
Angiograph
Orthopedics
Oncology
What is a contrast enhanced CT scan?
Iodine-based contrast injected into the patient
This will show up on a CT scan (to create iodine based contrast)
Negatives of CT scans
Imaging dose, small risk of cancer
Not ideal for moving parts (i.e. need a 4D scanner)
Not great with soft tissue definition
Uses of CT scans in cardiac/coronary?
Identify calcification
and occlusion of coronary arteries
What is stenoisis
the narrowing or restriction of a blood vessel or valve that reduces blood flow.
What stages of oncology are CT scans used in?
Diagnostic - identify tumour
Planning - delineation of tumour for radiotherapy
Treatment response - see if treatment has been successful, has tumour shrunk? Returned?
What is Filtered Back Projection?
Filtered back projection is an analytic reconstruction algorithm (removes blurring obtained from normal back projection). Backprojection reconstructs an image by taking each view and smearing it along the path it was originally acquired.
