2. 1. CT image= matrix with thousand of pixels
A computerized tomography
(CT) scan combines a series of
X-ray images(multiple images
in succession) taken from
different angles around your
body and uses computer
processing to create cross-
sectional images (slices) of the
bones, blood vessels and soft
tissues inside your
body. CT scan images provide
more-detailed information than
plain X-rays do.
3. Pixels are measured in hounsfield units(hu) based on
how much the x-ray beam is absorbed ,
which reflects density
4. When CT Scans are used
โข CT scans can produce detailed images of many structures inside the body, including the internal organs,
blood vessels and bones.
โข CT scans can help determine the location, size and shape of a tumour before having radiotherapy, or allow a
doctor to take a needle biopsy (where a small tissue sample is removed using a needle) or drain an abscess.
โข we can diagnose the conditions including damage to bones, injuries to internal organs, problems with
blood flow, stroke, and cancer.
โข To evaluate a change in the density of organs and pathological areas in Hounsfield units in contrasting in
the arterial, parenchymatous and venous phases
5. Procedure
โข During the scan, you'll usually lie on
your back on a flat bed that passes
into the CT scanner.
โข The scanner consists of a gantry or
ring and the patient slowly moves
through it. The gantry has detectors
and while it rotates around the patient
it shoots narrow beams of X-rays
through the body.
โข While each scan is taken, you'll need
to lie very still and breathe normally.
This ensures that the scan images
aren't blurred.
6. Contrast Materials
โข A special dye called contrast material which contain either barium or
iodine are needed for some CT scans, to examine organs that do not
have natural inherent contrast with surrounding tissue , it helps to
improve resolution of the final images produced with the the scan for a
more exact diagnosis
โข These are completely riskless and easily removed from the body
through urine.
โข These contract materials can be given through mouth , by injection and
as well as by enema
7.
8. CT images can be post processed into different planes
โข Axial โ looking at the patient from the feet up to the head
โข Sagittal โ looking at the patient from the side
โข Coronal โ looking the patient from the front
9. Advantages of CT scan
โข CT scans can provide detailed information to diagnose,
plan treatment for, and evaluate many conditions in adults
and children.
โข CT scans are quick(duration of 30mins for a full body
scan), painless and generally safe.
10. Disadvantages
โข Exposure to ionising radiations
โข There is a small risk you could have an allergic reaction
to the contrast dye used and you'll be exposed to X-ray.
โข Use of a contrast material is problematic for patients
with significant kidney problems.