CT

Tomos: slice

Graphein: to write

Past name: Computerized Axial Tomography

  • current helical scanner generation (7th) has many rows of scanners

  • good for every body part

  • can have 3D reconstruction

  • can do stereo taxis (procedure before surgery or radiation therapy) and abscess drainage

  • why is CT better? see superimposed structures, post-reconstruction work, differentiating substances, and assists IR

  • drawbacks: more radiation, increased cost, weight/size

  • what do we do for CT? Verify order, perp room and patient for scan, take scout image of PT anatomy, collimate and set parameters for scan, scan PT with or without contrast, finish reformatting images

  • Patient prep: check ID, verify allergies, verify contrast needed for the scan, creatin levels are important, check GFR (varies on age, sex, race), place IV

  • Where can contrast be? oral or IV which is more grey (blackness is air)

  • Localizer/scout image: help select parameters (SFOV and DFOV)

  • SFOV + DFOV: Make sure you have enough of PT and zoom in

  • Display windows: there’s soft tissue (see everything), bone (only white pixels), lung (everything that has a low pixel value)

  • reformatting: changing the actual image: coronal, sagittal, obliques, axials

  • reconstructions: magnifying, stacking, 3D, and other stuff

treatment planning:

  • drains: place using CT to insert and drain

  • IR biopsy: scan to find mass, put sticker over location for next scan

  • Surgical planning: for prosthetics or other fixing methods