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Computed tomography: Difference between revisions
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(Created page with "* Fundamentals of Computed Tomography (CT) ** Passing a rotating fan beam of x-rays through the patient *** Basically many x-rays at different angles around the patient ** Computer can generate many images from different angles from a single examination *** Can even generate a 3D image ** '''10 – 100x more radiation than x-ray''' ** '''The appearance of tissues on CT''' *** '''Densities are generally the same as for x-rays''' *** '''Bright on CT = high density''' *** '...") |
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**** '''Adjusting the “window length” or “window center” changes the brightness of the CT image''' | **** '''Adjusting the “window length” or “window center” changes the brightness of the CT image''' | ||
*** '''This manipulation changes the appearence of the picture to highlight certain structures''' | *** '''This manipulation changes the appearence of the picture to highlight certain structures''' | ||
** Bolus tracking | |||
***A technique used to optimising the timing of contrast CT | |||
*** The technician takes a picture before the bolus is injected | |||
*** Draws a ''region of interest'' (ROI) on the pulmonary trunk | |||
*** The machine will then continously take low resolution CT images through the pulmonary trunk | |||
*** The contrast bolus is injected | |||
*** When the Hounsfield unit of the ROI exceeds a certain threshold -> the contrast bolus has reached the pulmonary trunk -> the machine will start to take high resolution CT images of the whole lung | |||
<noinclude>[[Category:Radiology]]</noinclude> | <noinclude> | ||
[[Category:Radiology]]</noinclude> | |||