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Contrast CT of a patient with brain metastases from breast cancer, before (left) and after (right) injection of iodinated contrast. Iodinated contrast is a form of water-soluble, intravenous radiocontrast agent containing iodine , which enhances the visibility of vascular structures and organs during radiographic procedures.
An intravenous cannula is required for the administration of iodinated contrast. The typical dose is 30-40 g of iodine (corresponding to 20–30 cc of 370 mg/ml iodine solution). [10] However, for patients at high risk of contrast-induced nephropathy, it is possible to reduce the required amount of contrast using dual energy CT.
CT angiography is a contrast CT taken at the location and corresponding phase of the blood vessels of interest, in order to detect vascular diseases. For example, an abdominal aortic angiography is taken in the arterial phase in the abdominal level, and is useful to detect for example aortic dissection. [10]
Premedication is using medication before some other therapy (usually surgery or chemotherapy) to prepare for that forthcoming therapy. Typical examples include premedicating with a sedative or analgesic before surgery; using prophylactic (preventive) antibiotics before surgery; and using antiemetics or antihistamines before chemotherapy.
Iodinated contrast contains iodine.It is the main type of radiocontrast used for intravenous administration.Iodine has a particular advantage as a contrast agent for radiography because its innermost electron ("k-shell") binding energy is 33.2 keV, similar to the average energy of x-rays used in diagnostic radiography.
Contrast injection rate is 6 to 7 ml/sec with total volume of contrast at 10 ml. [8] [9] The frame rate of fluoroscopy is 2 to 4 frames/sec. [8] Neck extension can help to navigate into tortous cerival part of the internal carotid artery. [14] [15] At the level of carotid bifurcation, AP and oblique images are taken.
The information from a prior CT scan of the patient allows more accurate modelling of the behaviour of the radiation as it travels through the patient's tissues. Different dose calculation models are available, including pencil beam , convolution-superposition and monte carlo simulation , with precision versus computation time being the ...
In 1996, results were published of a study of 1369 subjects screened in Japan that revealed that 73% of lung cancers that were missed by chest x-ray were detectable by CT scan. [19] Among the earliest United States-based clinical trials was the Early Lung Cancer Action Project (ELCAP), which published its results in 1999. [ 20 ]