radioactive tracer

Examples of radioactive tracer in the following topics:

• Tracers

  • A radioactive tracer is a chemical compound in which one or more atoms have been replaced by a radioisotope.
  • A radioactive tracer is a chemical compound in which one or more atoms have been replaced by a radioisotope.
  • The underlying principle in the creation of a radioactive tracer is that an atom in a chemical compound is replaced by another atom of the same chemical element.
  • In a tracer, this substituting atom is a radioactive isotope.
  • There are two main ways in which radioactive tracers are used:

• Radioactive Decay Series: Introduction

  • Radioactive decay series describe the decay of different discrete radioactive decay products as a chained series of transformations.
  • Radioactive decay series, or decay chains, describe the radioactive decay of different discrete radioactive decay products as a chained series of transformations.
  • The intermediate stages often emit more radioactivity than the original radioisotope.
  • For example, natural uranium is not significantly radioactive, but pitchblende, a uranium ore, is 13 times more radioactive because of the radium and other daughter isotopes it contains.
  • Not only are unstable radium isotopes significant radioactivity emitters, but as the next stage in the decay chain they also generate radon, a heavy, inert, naturally occurring radioactive gas.

• Biological Effects of Radiation

  • Although radiation was discovered in the late 19th century, the dangers of radioactivity and of radiation were not immediately recognized.
  • In the case of external exposure, the radioactive source is outside (and remains outside) the exposed organism.
  • Examples of external exposure include a nuclear worker whose hands have been dirtied with radioactive dust or a person who places a sealed radioactive source in his pocket.
  • In the case of internal exposure, the radioactive material enters the organism, and the radioactive atoms become incorporated into the organism.
  • When radioactive compounds enter the human body, the effects are different from those resulting from exposure to an external radiation source.

• Emission Topography

  • The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule.
  • Three-dimensional images of tracer concentration within the body are then constructed by computer analysis.

• Natural Radioactivity

  • Detectable amounts of radioactive material occurs naturally in soil, rocks, water, air, and vegetation.
  • Radioactive material is found throughout nature.
  • The biggest source of natural background radiation is airborne radon, a radioactive gas that emanates from the ground.
  • Some of these decay products, like radium and radon, are intensely radioactive but occur in low concentrations.
  • Most of these sources have been decreasing, due to radioactive decay since the formation of the earth, because there is no significant source of replacement.

• Gamma Rays

  • Gamma rays are very high frequency electromagnetic waves usually emitted from radioactive decay with frequencies greater than 1019 Hz.
  • Gamma rays from radioactive decay are defined as gamma rays no matter what their energy, so that there is no lower limit to gamma energy derived from radioactive decay.
  • Gamma radiation from radioactive materials is used in nuclear medicine.
  • Originally, the electromagnetic radiation emitted by X-ray tubes almost invariably had a longer wavelength than the radiation (gamma rays) emitted by radioactive nuclei.
  • A notable example is extremely powerful bursts of high-energy radiation normally referred to as long duration gamma-ray bursts, which produce gamma rays by a mechanism not compatible with radioactive decay.

• Nuclear Stability

  • Also, only four naturally occurring, radioactive odd-odd nuclides have a half-life greater than a billion years:
  • During this process, the radionuclide is said to undergo radioactive decay.
  • Radioactive decay results in the emission of gamma rays and/or subatomic particles such as alpha or beta particles, as shown in .
  • Alpha decay is one type of radioactive decay.

• Matter and Antimatter

  • The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule.

• Calculations Involving Half-Life and Decay-Rates

  • An artefact is found to have radioactivity of 4 dpm per gram of its present C.
  • The following figure shows a simulation of many identical atoms undergoing radioactive decay.
  • The relationship between the half-life and the decay constant shows that highly radioactive substances are quickly spent while those that radiate weakly endure longer.
  • A simulation of many identical atoms undergoing radioactive decay, starting with four atoms (left) and 400 atoms (right).
  • The problems are taken from "The Joy of Physics. " This one deals with radioactive half-life.

• Gamma Decay

  • Gamma decay is a process of emission of gamma rays that accompanies other forms of radioactive decay, such as alpha and beta decay.
  • Gamma rays from radioactive decay are defined as gamma rays no matter what their energy, so there is no lower limit to gamma energy derived from radioactive decay.