Hounsfield Units (HU) are used to quantify the density of tissues in CT images. Water is assigned a value of 0 HU, and other substances are assigned values relative to that.
The gantry is the part of the CT scanner that houses the X-ray tube and the detector array. It rotates around the patient during the imaging process.
The gantry of the CT unit has detectors. They gauge the transmitted photons from the X-ray tube that traverse the patient. By measuring attenuation, they turn the photons into electrical impulses. An X-ray photon must enter the detector, collide with the detection atom, and cause a quantifiable event of electricity or light to produce a signal. A very modest electrical signal from the detectors' detectable light or energy must be processed by the data acquisition system (DAS) before it can be amplified and converted into a real CT image. CT scanners from the first generation only have one detector. A linear detector array, or a collection of sensors arranged in a straight line, is a feature of second-generation scanners. The multiple detector array along a curve with full circular detector rotation is a feature of third-generation scanners. A rotating fan beam is contained within a fixed ring of detectors in fourth-generation scanners. With the advent of multi-row detector scanners, or MDCT, it was possible to gather data for each tube rotation from many anatomical slices. This enabled thinner slices, faster scans, and greater anatomical coverage. Third-generation technology is used by MDCT, which has several parallel detector arrays.
The CT angiography procedure is less intrusive and risky than traditional angiography because it only involves the insertion of a catheter into a vein rather than an artery.
Perfusion CT is a technique used to assess blood flow and perfusion in tissues. It involves tracking the passage of contrast material through blood vessels to evaluate tissue viability.
Slice thickness in CT imaging refers to the spacing between consecutive image slices. It determines the level of detail and resolution in the resulting images.
CT provides better soft tissue contrast compared to conventional X-ray imaging, making it useful for visualizing various structures within the body.
CT imaging is based on the principle of X-ray absorption by different tissues in the body. It uses X-rays to create cross-sectional images of the body's internal structures.
Iodine-based contrast agents are commonly used in CT imaging to enhance the visibility of blood vessels and other structures due to their ability to absorb X-rays.
A CT scout image is a low-dose X-ray image used to estimate the size of the patient and determine the appropriate scanning parameters before the actual CT scan.
The solid-state crystalline detector is the most prevalent and effective variety. The photon strikes the crystalline sensor after passing through the patient. The crystals transform the energy into light, which is then converted into an electrical signal. The xenon gas detector is an alternative sort of detector. These are ineffective and are used sparingly today. The xenon gas is ionized when an X-ray beam strikes the xenon gas detector. Ions move to areas with a positive charge, charge plates, and produce electricity. The crystalline sensors have been used in constructing all previous multi-row detectors and all new detector systems.
Iodine is the contrast material used in CT. Contrast agents in other imaging procedures, like magnetic resonance imaging and ultrasonography, offer other alternatives.
Cardiac CT is a specialized type of CT scan used to image the coronary arteries and assess the health of the heart.
The effects of ionizing radiation are especially noticeable in the pediatric population. CT makers and radiology experts created color-coded weight-based procedure selections to help lower the radiation dose received by the pediatric population during each CT test. Thanks to these color-coded protocols, the technologist will be able to choose a protocol with specific technical parameters for a patient's size and weight.
A polychromatic beam can become monochromatic with the aid of filtering. The highest energy or longest wavelengths are reduced. As a result, the radiation dose to the patient is decreased without significantly affecting the signal being monitored. The remaining X-rays are less susceptible to beam hardening and the artifacts it produces.
The objects could obstruct the X-rays and cause visual blur. However, they do not present a threat.
