Radiation terminology

Understanding how radiation detection occurs requires a working knowledge of basic terminology. 

Infrared radiation was discovered by Herschel [58] in 1800, using a mercury thermometer to detect sunlight dispersed by a prism. However, the Latin poet Lucretius in his De rerum Natura (On the Nature of Things, about 50 BC) clearly showed a clear feeling of the infrared radiation. Of course Lucretius s terminology was far from the modern one, and he had no thermometer at his disposal ... 

A variety of units have been used for the assessment of exposures to ionizing radiation. The current international standard terminology is shown in Table 32.3. This chapter uses the new terminology exclusively this frequently necessitated data transformation of units from early published accounts into the currently accepted international terminology. 

Schrodinger s equation is widely known as a wave equation and the quantum formalism developed on the basis thereof is called wave mechanics. This terminology reflects historical developments in the theory of matter following various conjectures and experimental demonstration that matter and radiation alike, both exhibit wave-like and particle-like behaviour under appropriate conditions. The synthesis of quantum theory and a wave model was first achieved by De Broglie. By analogy with the dual character of light as revealed by the photoelectric effect and the incoherent Compton scattering... 

Waveform can be defined in at least two different ways which are relevant to spectroscopic measurements. Wavelength (X.) is defined as the distance between successive peaks (Figure 2.1) and is measured in subunits of a metre, of which the most frequently used is the nanometre (10 9m). An angstrom unit (A) is not acceptable in SI terminology but is still occasionally encountered and is 10-10m (i.e. 10 A = 1 nm). The frequency of radiation (nu, v) is defined as the number of successive peaks passing a given point in 1 second. Hence the relationship between these two units of measurement is ... 

Terahertz, or far infrared spectroscopy, covers the frequency range from 0.1 to lOTHz (300 to 3cm ) where torsional modes and lattice vibrations of molecules are detected. It is increasing in use in many application areas, including analysis of crystalline materials. Several dedicated conunercial instruments are available which use pulsed terahertz radiation which results in better signal to noise than those using blackbody sources for radiation (and associated with the terminology far infrared spectroscopy). Work using extended optics of FTIR instrumentation as weU as continuous-wave source THz has also been recently reported. ... 

It is important for the future that protocols and results of hadron therapy be reported and analyzed using the terminology, definitions, concepts, and approaches currently in use for the other radiation therapy modalities [7,53]. 

As fractionated photon beam therapy is the reference radiation therapy modality, used for more than 80% of the patients, the terminology in use for photons should be applied for... 

IAMAP, Terminology and Units of Radiation Quantities and Measurements, Radiation Commission of the International Association of Meteorology and Atmospheric Physics, Boulder, CO, 1978. 

ASTM E170 Standard Terminology Relating to Radiation Measurements and Dosimetry... 

SPECTROSCOPE. Several types of instruments for producing Oand viewing spectra are included under this term. Variations in form are due, not only to differences in principle, but also to the type of radiation or phenomena to be examined. Terminology employed in this field of instrumentation is described under Spectro Instruments. 

As an example, for styrene at 0°C. the following data are typical (30) rate of polymerization = 14.5%/hour, dose rate = 2.2 X 103 rads/hour, average DP 103. Since 1 rad corresponds to the absorption of 100 ergs/gram of material, it can be demonstrated, on the basis of the above values, that approximately 6 X 105 monomer units are incorporated into polymer for each 100 e.v. of energy absorbed. In conventional radiation chemistry terminology this would be expressed as G(.m0nomer)... 

The various terms that are used for the description of the emission of electromagnetic radiation from a radiant source or for the receipt of electromagnetic radiation by a specified surface element are summarized in Tab. 3-9. The terminology of electromagnetic radiation measurement is divided into radiometry and the subset of photometry (Fig. 3-18). The former is the science that involves the energy measurement of electromagnetic radiation in general. The latter is applied for the same purpose when visible radiation is to be described or measured in relation to the human eye s response. Important photometric quantities are for example luminous flux, luminous intensity, illuminance and luminance (McCluney, 1994). Every photometric quantity has its counterpart in radiometry, and vice versa. 

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