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Method of computer tomography of the head
Last reviewed: 17.10.2021
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Preparing for a computer tomography scan of the brain
Before contrast CT scan, the patient should refrain from eating for 4 hours before the study.
Before the study, the patient is informed about the procedure for the procedure, if a CT scan is to be performed, the patient should be warned that after the introduction of the contrast medium, a feeling of heat and tidal flare, a headache, a taste of metal in the mouth, nausea or vomiting may appear.
The patient should be dressed in comfortable light clothing, all metal objects in the field of a computer tomograph should be removed. With emotional excitement and motor anxiety prescribe sedatives.
The doctor is obliged to find out and fix in the medical history the patient's intolerance to iodine (seafood), contrast substances. With intolerance to iodine, it is necessary to prophylacticly prescribe antiallergic drugs or to refrain from contrasting.
How is CT of the brain performed?
The patient is placed on his back on the X-ray table, his head is fixed with straps if necessary and he asks the patient not to move.
Tomography is performed together with the rotation of the scanner around the patient's head in 1 cm increments along an arc of 180 °, producing a series of slices, or scans. Then, if necessary, intravenously inject a contrast agent and make another series of scans. The information about the slices is stored digitally in the computer, displayed and displayed as a photograph.
First, a cut in the sagittal projection (topogram) is performed, on which the markings of the forthcoming sections located parallel to the orbitomal line are drawn. This line is drawn from the superciliary arcs to the external auditory meatus, and then, repeatedly repeating, the marking is applied over the whole scanning zone upwards. The standard technique of slice planning in the computed tomography of the head allows one to reliably compare the data of several CT studies. To reduce artifacts due to the distribution of X-ray rigidity, thin sections (2-3 mm) are used for visualization of the posterior cranial fossa, whereas for supratentorial structures of the brain located above the pyramids of the temporal bones, it is desirable to establish a large width of cuts (5 mm).
Obtained images in the computed tomography of the head represent a bottom view (caudal side) of the cross section of the head, so the sides turn upside down. For example, the left lateral ventricle is visualized on the right side of the image, and the right one on the left. An exception to this rule are computerized tomograms for the planning of neurosurgical operations. Then they are a top view (from the cranial side, where the right = right), which corresponds to the neurosurgeon's habitual view of the patient's head during trepanation.