External radiation sources

Sensitive parts of the body with respect to external radiation sources are the haema-togenous organs, the gonads and the eyes. Less sensitive parts are the arms and hands, the legs and feet, the head (except the eyes) and the neck. The ion dose rate transmitted by a point-like y-radiation source of activity A at the distance r is 

The dose rate constant ky for y radiation depends on the energy of the y rays and on the decay scheme of the radionuclide. Values of ky for various radionuclides are listed in Table 22.3. For rough estimation, it is useful to know that a point-like radiation source of 1 GBq emitting y rays with energies of 1 MeV transmits an ion dose rate of about 0.03 R h at a distance of 1 m. 

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ICRU (1988). International Commission on Radiation Units and Measurements. Determination of Dose Equivalents from External Radiation Sources Part2, ICRU Report 43 (International Commission on Radiation Units and Measurements, Bethesda, Maryland). 

As an example of a modern commercial interferometer, the optical diagram of a Bruker IFS 66, is shown in Fig, 3.4-1. It allows working in the optical range from 40000 to 20 cm (250 nm to 500 im), to exchange different internal and external radiation sources and detectors, and to connect various accessories, such as a Raman module or an infrared or Raman microscope. 

Medical applications External radiation sources (medical application of X rays or radionuclides) Diagnosis 1-lOmSv 0.1-1 mSv a 0.5 mSv/y... 

Measures for protection against exposure to an external radiation source are as follows ... 

ICRU, Determination of Dose Equivalents Resulting from External Radiation sources. Report 39, ICRU Publications, Bethesda, 1985. 

The cardinal principles of radiation protection from external radiation sources are governed by four factors time, distance, shielding, and activity. 

If the intended use of the radionuclide is as an external radiation source (A4a - B2 - C2.1 or C3) its chemical matrix is of minor importance. Such sources are used for radiation treatment of cancer (C3b), radiation sterilization of food (C3c), etc. The radiation ects on biological systems are discussed separately in Ch. 18. In this chapter we focus our interest on radionuclides with specific chemical properties, in the order of column C, Table 9.3. 

The configuration of the common components of dispersive spectroscopy systems is shown for the most used types of spectroscopy. In layouts 1 and 3, an external source of radiation is required, but for 3, the source is generally oriented at right angles to the sample. Emission, layout 2, does not require an external radiation source the excited sample is the source. For absorption, fluorescence, phosphorescence, and scattering, the source radiation... 

An insufficiently shielded external radiation source can influence background measurements from some distance. Airborne radionuclides typically are gaseous radon and its particulate progeny, but after nuclear tests or major nuclear accidents may include fission and activation products. Efforts should be made to control such exposures for long-term radiation background stability. 

There was also described and discussed the relatively new Fourier transform infrared emission spectroscopy (IRES), its principle, an appropriate FT-IRES setup and applications. FT-IRES is unique in that it does not require an external radiation source, because the sample itself is the source. The radiation emitted from the sample is collected and sent to the detector. The ratio of the sample signal to that from a black body source represents the spectrum. However, appli-... 

CL is an attractive detection method for CE in part due to its simple instrumentation. An external radiation source is not required, reduces instrument cost, complexity, as well as the overall footprint of the instrument. In addition, since there is no background from an excitation source, there is no need to filter the collected radiation, which increases detection efficiency. In its simplest form, a CE-CL instrument can consist of only a capillary, power supply, and a detector, such as a PMT or photodiode detector. The small footprint of such instrumentation is particularly attractive for microscale total analysis systems (p,TAS) or lab-on-a-chip applications. - " ... 

Personnel monitoring is usually required when (1) workers are likely to receive in 1 year 10% of the annual limit of exposure from the external radiation source, and (2) individuals enter high... 

The cascade header enrichment meter (CHEM) is another application that uses HPGe detection to qualitatively confirm the absence of HEU in centrifuge cascade header pipes of enrichment plants (Close et al. 1998). The technique uses an external radiation source ( Co) and a special collimated HRGS with specific software to control, perform, and evaluate X-ray fluorescence (XRF) and passive measurements. The XRF measurement provides the amount of total uranium in the UFg gas. The deposit on the inside surface of a header pipe requires two measurements of the gamma ray at 186 keV with different geometries to determine the amount of in the gas alone. The level of enrichment of uranium in the gas of the header pipe can then be determined independently of the gas pressure. 

Active neutron content of HEU fuels total fissile content of mixed (U.Pu) fuels can be operated In passive mode for Pu fuels. External radiation source required relat1vely bulky and complex Instrumenta-t1on fue1 handling required. 

Co cobalt-60 5.3 years beta, gamma external radiation source for cancer treatment... 

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