Neutron capture is a process in which a neutron collides with a nucleus and becomes part of this nucleus caused by nuclear forces. It interacts without release of another heavy particle. A gamma ray photon is emitted as an immediate result of the neutron capture process. Through the neutron capture the nucleus becomes a heavier isotope of the same element. The kind of decay depends on the isotope and its stability.
This process is for example part of the neutron activation analysis, in which a sample is positioned in a neutron beam and also used in the 'boron neutron capture therapy'.

See also Thermal Neutrons, Epithermal Neutron, Neutron Activation Analysis, Nuclear Charge Number, Deuteron, Isomeric Transition, Isotones, N P Reaction.

Patents can unintended respond with an idiosyncratic reaction to the application of contrast media. Idiosyncratic reactions to contrast agents start usually within 20 minutes after injection and occur more frequently in patients 20 to 40 years old.
Idiosyncratic reactions may or may not be dependent on the amount of dose injected, the speed of injection, the mode of injection and the radiographic procedure.


See also Adverse Reaction and Anaphylactoid Reaction.

The first-generation contrast agents were all ionic monomers, consisting of a tri-iodinated benzene ring with 2 organic side chains and a carboxyl group. Diatrizoate or iothalamate are common iodinated anions, conjugated with a cation, sodium or meglumine. The ionization at the carboxyl-cation bond makes the agent water soluble.
Ionic monomers have the highest osmolality (high-osmolar contrast media (HOCM) possess an osmolality seven to eight times higher than plasma) of the different groups of contrast agents (CM ratio=1.5) and the lowest viscosity. The osmolality in solutions of ionic monomers ranges from 600 to 2100 mOsm/kg (human plasma = 290 mOsm/kg). These high osmolality is related to some of the adverse reactions. HOCM's have been widely replaced by newer contrast agents with improved tolerability and safety profiles.
Examples of HOCM's are Renografin®-60, Hypaque 76, Hypaque Meglumine, Hypaque Sodium and Conray®.

See also Ionic Contrast Agents.