The Auger electron is emitted caused by the Auger effect. The kinetic energy of the Auger electron depends on the type of atom and the chemical environment. The energy of the Auger electron is in the range between 280 eV (electron volt) and 2100 eV. These different energy levels are utilized for chemical analysis.

See also Auger Effect, Compton Electron, Conversion Electron, Initiating Electron and Auger Pierre Victor.

Barium sulfate (BaSO4) is an inert and insoluble white powder with high density. Barium belongs chemically to the group of heavy metals. Mixed with water and additional ingredients (e.g., sweetening agents), barium sulfate is the preferred positive contrast agent for abdominal x-ray and computed tomography examinations. The extremely low solubility of barium sulfate protects patients from absorbing harmful amounts of the metal (water soluble metal compounds are often highly toxic). The high density in x-ray examinations is related to the high atomic number, since large nuclei absorb x-rays much better than smaller nuclei.
Barium sulfate agents for opacification of the gastrointestinal tract are not absorbed or metabolized and are resistant to dilution. These contrast agents are opaque white suspensions and usually swallowed or administered as an enema. They provide better delineation of mucosal details and are less expensive than water-soluble iodinated contrast media. The elimination rate is a function of gastrointestinal transit time. After GI application, it leaves the body with the feces.

Contraindications of barium sulfate products in case of known or suspected:

Henri Becquerel demonstrated beta particles in 1900. Identical with electrons is there negative charge at -1. Their mass is 549 millionths of one AMU, 1/2000 of the mass of a proton or neutron. Beta particles consist of high energetic electrons emitted by radioactive nuclei or neutrons. By the process of beta decay, one of the neutrons in the nucleus is transformed into a proton and a new atom is formed which has one less neutron but one more proton in the core. Beta decay is accompanied by the emission of a positron (the antiparticle of the electron), a positive charged antineutrino. Beta particles have a greater range of penetration than alpha particles but less than gamma rays or x-rays. The name beta was coined by Rutherford in 1897. The traveling speed of beta particles depends on their energy. Because of their small mass and charge beta particles travel deep into tissues and cause cellular damage and possible cancer.

See also Radiation Shielding.

The CM (contrast material) ratio refers to the ratio between the number of iodine atoms and the number of particles in the solution. The CM ratio is fundamental in the chemical analysis of contrast media.

See also Ionic Dimer, Ionic Monomer, Nonionic Dimer and Nonionic Monomer.

(CTA) A computed tomographic angiography or computerized tomography angiogram is a diagnostic imaging test that combines conventional CT technique with that of traditional angiography to create images of the blood vessels in the body - from brain vessels to arteries of the lungs, kidneys, arms and legs.
High resolution CT scans with thin slices and intravenous injection of iodinated contrast material provide detailed images of vascular anatomy and the adjacent bony structures. CTA requires rapid scanning as the imaging data are typically acquired during the first pass of a bolus of contrast medium. The selection of acquisition timing is important to optimize the contrast enhancement, which is dependent on contrast injection methods, imaging techniques and patient variations in weight, age and health. CT angiography is less invasive compared to conventional angiography and the data can be rendered in three dimensions.

CTA techniques are commonly used to:
See also Cardiovascular Imaging, Magnetic Resonance Angiography MRA, Coronary Angiogram, Computed Tomography Dose Index and Computed or Computerized Axial Tomography.