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CT scanning can perform a virtual colonoscopy with greater accuracy and less discomfort for the patient than a traditional colonoscopy. [143] [144] Virtual colonography is far more accurate than a barium enema for detection of tumors and uses a lower radiation dose. [145] CT is a moderate-to-high radiation diagnostic technique.
Spiral CT can achieve improved image resolution for a given radiation dose, compared to individual slice acquisition. Most modern hospitals currently use spiral CT scanners. Willi Kalender is credited with invention of the technique, and uses the term spiral CT. [6] Kalender argues that the terms spiral and helical are synonymous and equally ...
4DCT will usually involve a gating technique, such as breathing tracking, so that image acquisition is automatically triggered at set points. [9] This gating can also be applied at treatment, where the radiotherapy beam is only switched on at certain points in the breathing cycle (as in the deep inspiration breath-hold technique). [10]
Low-dose high-resolution (1.25 mm) chest CT. HRCT is performed using a conventional CT scanner. However, imaging parameters are chosen so as to maximize spatial resolution: [1] a narrow slice width is used (usually 1–2 mm), a high spatial resolution image reconstruction algorithm is used, field of view is minimized, so as to minimize the size of each pixel, and other scan factors (e.g. focal ...
This technique is computationally fast, but the 2D results do not provide a good sense of depth of the original data. To improve the sense of 3D, animations are usually rendered of several MIP frames in which the viewpoint is slightly changed from one to the other, thus creating the illusion of rotation.
For polytrauma patients, aggressive use of full-body CT scanning improves early diagnosis of injury and improves survival rates, [1] with widespread adoption of the technique seen worldwide. [2] Full-body CT scans are not indicated in patients with minor or single system trauma, and should be avoided in such patients. [1]
Electron beam CT scanners are considered a fifth generation CT scanner, with first generation being the pencil beam with translation and rotation, second generation being a fan beam with similar motion to its predecessor, third generation having both rotating fan beam and detectors and fourth generation being a fan beam with a rotating movement but fixed detector.
Tomographic systems have significant variability in their applications and geometries (locations of sources and detectors). This variability creates the need for very specific, tailored implementations of the processing and reconstruction algorithms. Thus, most CT manufacturers provide their own custom proprietary software.