Radiation dosage and

The concentration of trapped radicals in the cellulose lattice depended on the radiation dosage and the amount of moisture present in the cellulose during irradiation. The trapped radical yield in irradiated cellulose, containing about 7% moisture, is shown in Table I. If cellulose was irradiated dry (about 0.5% moisture) and in vacuum, an initial yield of 2.5-3 times that shown was obtained however, the concentration of the radicals decreased rapidly on exposure of the irradiated, dry cellulose to moisture (26). 

Patients receiving radiation therapy may experience complications including severe esophagitis, fatigue, radiation pneumonitis, and cardiac toxicity. These toxicities are usually more common and severe when radiation is combined with chemotherapy. The patient s baseline performance status and the degree of pulmonary dysfunction (e.g., chronic obstructive pulmonary disease from years of tobacco use) must be considered in the decision of radiation dosage and fractionation. 

The y-irradiation induction of changes in linen and cotton celluloses has been studied by e.s.r. spectroscopy. The number of carboxy- and carbonyl-groups introduced into these celluloses increased with increasing radiation dosage, and their chains were cleaved to the same extent. 

One early program carried out at AUied-Signal, Inc. proposed the use of conductive polymers in remotely readable indicators (210). Conductivity changes induced in the conductive polymer could be read externally and the history of the sample known. Systems designed to detect time—temperature, temperature limit, radiation dosage, mechanical abuse, and chemical exposure were developed. 

Torlon-type polymers are unaffected by aliphatic, aromatic, chlorinated and fluorinated hydrocarbons, dilute acids, aldehydes, ketones, ethers and esters. Resistance to alkalis is poor. They have excellent resistance to radiation. If a total of 10 Mrad is absorbed at a radiation dosage of 1 Mrad/h the tensile strength decreases by only 5%. 

Commercially viable systems for the decolorisation of spent dyebaths can be based on hydrogen peroxide treatment initiated by UV radiation. A representative selection of six disulphonated monoazo acid dyes and two disazo disulphonated types was exposed for various times in a pilot-scale photochemical reactor of this kind. The controlling parameters were dye structure, pH, peroxide dosage and UV light intensity [39]. In a wider survey of the response of various classes of dyes to the combination of UV radiation and hydrogen peroxide, viable candidates for further in-plant treatment trials were the water-soluble reactive, direct, acid and basic classes. On the other hand, water-insoluble colorants such as disperse and vat dyes did not appear to be viable [40]. 

Other, non-linear, proposals for the relation between property and radiation dosage include a power law and an exponential relationship ... 

For the sake of brevity detailed tables of all tests performed are shown for duPont ionomer resins only (Tables II, III, IV, VI to X). The other ethylene copolymers were similarly treated and evaluated. The effects of increasing radiation dosages on certain physical properties of selected duPont ionomers are shown graphically in Figures 1, 2, and 3. 

The relationship between conveyor speed with which a material can be moved under the electron beam and the obtainable radiation dosage, assuming 50% beam absorption efficiency, is shown in Table XII. These data show that a 1.0 specific gravity material could obtain a dosage of... 

The final problem to consider is that owing to attenuation the radiation dosage throughout the sample, and consequently the concentration of contaminants, will not be uniform. A method for doing this is to make dosage measurements throughout the absorber by use of a technique such as has been described by Henley (H13). 

There is an increased incidence of late hypothyroidism in patients with autoimmune hyperthyroidism, but the risk increases markedly after extensive thyroid surgery and especially after I treatment. Analysis of the cumulative incidence of hjrpothjroidism shows two phases an early phase of radiation death of thyroid cells, depending on the I dosage and occurring during the first 1-2 years after treatment a second period of a lower (0.5-3.5% per year) but hfe-long risk of developing hypothyroidism for a variety of reasons (natural history of the disease, autoimmune processes) (see Table 1) (12-14). 

Discuss the interactions of radiation with various kinds of matter and the measurement of radiation dosage (Section 19.4, Problems 33-36). 

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