A computed tomography scanner — is a combination of an X-ray machine and a computer. The X-ray machine makes X-ray images of a patient at different angles (the so-called scans) that are further processed and summed up by the computer. You end up with an image that allows doctors to "peep" inside the patient’s body.
CONSTRUCTION OF A COMPUTED TOMOGRAPHY SCANNER
Each device comprises as follows:
- - A gantry including an X-ray source, signal detectors, and a system that ensures the required movements of the detectors and the X-ray source.
- - A data conversion system that is recorded by the detectors.
- - A computer that performs calculations necessary to produce an image.
- - A system for recording, reproducing, and displaying the obtained images.
The gantry aperture diameter makes an average of 70 cm. However, there are machines with a larger diameter of 80–90 cm that are generally applied in oncology, where a good accessibility of abnormal focus must be necessarily provided. If required, the scanning system can tilt forward or backward up to 30 degrees.
Rotation time is one of the gantry characteristics, which is a parameter of time required for full rotation of the tube-detector system around the study object. The longer the time of rotation is, the higher the temporal resolution is. This property is of high importance for the study of fast processes and diagnostics of children. For example, the rotation time of the tomography scanners used in routine studies is about 0.5–0.8 seconds, and in the heart studies — 0.3–0.4 seconds.
The scanning system (gantry) consists of a detection system and an X-ray tube. The third generation of tomography scanners provide for the tube and detector being mounted on the same frame.