Internal dosimetry
Encyclopedia
Internal dosimetry provides methods for calculation of radiation dose and risks from radionuclides incorporated inside human body. The Radionuclide deposited in human body will irradiate that person and will give dose to body until excreted or completely decayed from the body.

Routes of intake

There are four routes of intake (of radionuclide) namely,
  • Inhalation
  • Ingestion
  • Injection
  • Absorption

Inhalation
Inhalation
Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli....

 is the most prominent route of intake. In a radioactive area, radionuclide particulate may be suspended in the air and can enter the body by inhalation. These particulates may be deposited in different parts of the respiratory tract depending upon their aerodynamic diameter
Aerodynamic diameter
Aerodynamic diameter is a physical property of a particle in a viscous fluid such as air. In general, particles have irregular shapes with actual geometric diameters that are difficult to measure. Aerodynamic diameter is an expression of a particle's aerodynamic behavior as if it were a perfect...

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Monitoring techniques

In-vivo monitoring

Internal dose monitoring of the radionuclides which emit radiation which can penetrate out of the body.For example X-rays, gamma rays of sufficient energy.

Monitoring Systems

Whole Body Counter

A Whole Body Counter has a low background arrangement with counting systems
  • NaI(Tl) detectors for high energy photon detection
  • Phoswich detectors with Be window and thin NaI(Tl)crystal and thick CsI(Tl)or CsI(Na), for low energy (<100 keV) photon detection


HPGe detectors are replacing detectors for measuring the low energy and high energy photons with appropriate electronic systems.

Calibration of these systems is carried out with different type of physical and mathematical phantoms. Physical phantoms include BOMAB
Bomab
The BOttle MAnnikin ABsorber phantom was developed by Bush in 1949 and has since been accepted in North America as the industry standard for calibrating whole body counting systems....

, LLNL, JAERI, thyroid and the knee phantoms. Some of the renowned mathematical phantoms are MIRD, CRISTY and nowadays voxel phantoms.

In-vitro monitoring


Monitoring of the radionuclides present in the body using the bio-assay sample taken out of the body.For example urine sample,sweat, fecal sample etc. Computer programs can be used for bioassay evaluations.
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