Radiation detriment

When the entire body or parts of the body are irradiated externally, individual tissues and organs receive different absorbed doses. In order to relate the absorbed doses in tissue from non uniform irradiation to radiation detriment in humans, a quantity is required which reflects the relative effects of different types of radiation and the relative radiosensitivity of the irradiated organs and tissues. 

Also, a dose limit expressed in the quantity He does not carry the same implications for radiation protection as a numerically equal dose limit expressed in the quantity E. For example, a value of He = 10 mSv and a value of = 10 mSv do not carry the same implications for radiation detriment in a working population, as noted in Sections 1.2,2 and 1.2,3. One must be consistent in using He or E only in the context of its corresponding radiation protection system [i.e., He with the ICRP (1977a) or the NRC (1991) systems E with the ICRP (1991) or the NCRP (1993) systems]. 

Medical exposures should be justified by weighing the diagnostic or therapeutic benefits they produce against the radiation detriment they might cause, taking into account the benefits and risks of available alternative techniques that do not involve medical exposure. 

A survey of planar and SPECT imaging studies found that similar radiation doses were associated with planar than with SPECT studies. The radiation detriment to the subject from a given study is... 

The risk of radiation detriment is small. Precautions are less important. 

A practice which entails or that could entail exposure to radiation should only be adopted if it yields sufficient benefit to the exposed individuals or to society to out-weigh the radiation detriment it causes or could cause (justification principle). 

No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the exposed individual or to society to offset the radiation detriment it causes. (Justification of a practice.)... 

The design target for the long term collective dose should preferably be expressed in terms of man Sv/unit of electricity generation, indicating the ratio of the radiation detriment to the benefit (the energy produced). 

A practice shall be justified on the grounds that it produce sufficient benefit to the exposed individual(s) and to society to outweigh the radiation detriment that it... 

Polyimide. Polyimide is a biaxiaHy oriented high performance film that is tough, flexible, and temperature- and combustion-resistant. Its room temperature properties compare to poly(ethylene terephthalate), but it retains these good characteristics at temperatures above 400°C. Its electrical resistance is good and it is dimensionally stable. The principal detriment is fairly high moisture absorbance. The main uses are for electrical insulation, particularly where high temperatures are prevalent or ionizing radiation is a problem. The films may be coated to reduce water absorption and enhance... 

The i j -configuration of the 6,7-double bond in pre-vitamin D is critical to its subsequent thermal rearrangement to the active vitamin. A photochemical isomerization of pre-vitamin D to yield the inactive trans-isoTnen occurs under conditions of synthesis, and is especially detrimental if there is a significant short wavelength component, eg, 254 nm, to the radiation continuum used to effect the synthesis. This side reaction reduces overall yield of the process and limits conversion yields to ca 60% (71). Photochemical reconversion of the inactive side product, tachysterol, to pre-vitamin D allows recovery of the product which would otherwise be lost, and improves economics of the overall process (70). 

Limitations of Plasma CVD. With plasma CVD, it is difficult to obtain a deposit of pure material. In most cases, desorption of by-products and other gases is incomplete because of the low temperature and these gases, particularly hydrogen, remain as inclusions in the deposit. Moreover, in the case of compounds, such as nitrides, oxides, carbides, or silicides, stoichiometry is rarely achieved. This is generally detrimental since it alters the physical properties and reduces the resistance to chemical etching and radiation attack. However in some cases, it is advantageous for instance, amorphous silicon used in solar cells has improved optoelectronic properties if hydrogen is present (see Ch. 15). 

The use of microwave techniques introduces unique challenges in safety considerations. Guidelines for the use of microwave systems in the analytical laboratory have been published and most of these also apply to microwave-assisted organic chemistry [13]. The health hazards of microwave radiation are also still under investigation, and it is not yet known whether or not low level exposure is detrimental. Recom-... 

Lower doses (at or below 200 Gy) of irradiation coupled with 35 days of storage at 10°C were not harmful in the retention of lycopene and other health-promoting compounds in early-season grapefruit, but higher doses (400 and 700 Gy) and 35 days of storage had detrimental effects. However, no significant effect of radiation and storage was observed in late-season fruit (Patil and others 2004). 

B.5.3 Effective Dose Equivalent and Effective Dose Equivalent Rate. The absorbed dose is usually defined as the mean absorbed dose within an organ or tissue. This represents a simplification of the actual problem. Normally when an individual ingests or inhales a radionuclide or is exposed to external radiation that enters the body (gamma), the dose is not uniform throughout the whole body. The simplifying assumption is that the detriment will be the same whether the body is uniformly or nonuniformly irradiated. In an attempt to compare detriment from absorbed dose of a limited portion of the body with the detriment from total body dose, the ICRP (1977) has derived a concept of effective dose equivalent. 

The dose rate affects both the yield and chain length of the grafted material. Air has a detrimental effect on grafting since it inhibits the reaction, which is consistent with other radiation-induced free radical reactions. Increasing the temperature of fhe graffing sysfem increases the yield. This is very likely because raising the temperature increases the diffusion rate of the monomer into the substrate. ... 

---