Radiation absorbed dosage

The rad, or radiation absorbed dosage, provides more meaningful information than either of the previous units of measure. It takes into account the nature of the absorbing material. It is defined as the dosage of radiation able to transfer 2.4 X 10 cal of energy to one kg of matter. 

Rad a unit of radiation dosage corresponding to 10 2 J of energy deposited per kilogram of tissue (from radiation absorbed dose). (21.7)... 

Much of his work, discussed in Chapter 8 of this book, is important because chemical actinometry is the only way of truly measuring the absorbed dosage of the incident radiation. A chemical actinometer corrects for container problems such as reflection, refraction, geometry, absorption, internal reflections, etc. 

Curie = A physical amount of radioactive material 1 Megacurie (MCI) = 1,000,000 Curies 1 Kilocurie (kCi) = 1,000 Curies 1 Millicurie (mCi) = 0.0001 Curies 1 Microcurie (uCi) = 0.000001 Curies Roentgen = Ionization per cm of dry air RAD = Radiation absorbed dose — Dosage REM = Biological effects... 

Experimental studies have shown that vinylene concentration is constant with sample thickness (Costa et al. 1998). Alkyl macroradicals produced by gamma radiation are homogeneously distributed within the UHMWPE component because vinylene are the primary product of interaction between polyethylene and high-energy radiation. In e-beam irradiation, the radical distribution is a function of depth because of the cascade effect, which leads to a subsurface maximum in the absorbed dosage. 

If a 50-kg person is uniformly irradiated by 0.10-J alpha radiation, what is the absorbed dosage in rad and the effective dosage in rem ... 

The ROENTGEN, R, the standard used in measuring the intensity of X or y radiations, is defined as the quantity of X or y radiation that produces 1.61 X 10 ion pairs in 1 g of air, equivalent to the absorption of 84 ergs/g of air. The RAD (radiation absorbed dose) is the dosage of any nuclear emanation equivalent to the absorption of 100 ergs/g of any material. 

The degree to which radiation exposure affects FEP resins is determined by the energy absorbed, regardless of the type of radiation. Changes in mechanical properties depend on total dosage, but ate independent of dose rate. The radiation tolerance of FEP in the presence or absence of oxygen is higher than that of PTFE by a factor of 10 1. 

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%. 

Rep—Roentgen equivalent, physical A former unit of ionizing radiation equivalent to the dosage of 93 ergs absorbed per gram of tissue (93 erg/gm=0.93 rad). 

Attenuated total reflection (ATR) is the most common reflectance measurement modahty. ATR spectra cannot be compared to absorption spectra. While the same peaks are observed, their relative intensities differ considerably. The absorbances depend on the angle of incidence, not on sample thickness, since the radiation penetrates only a few micrometers into the sample. The major advantage of ATR spectroscopy is ease of use with a wide variety of solid samples. The spectra are readily obtainable with a minimum of preparation Samples are simply pressed against the dense ATR crystal. Plastics, rubbers, packaging materials, pastes, powders, solids, and dosage forms such as tablets can all be handled directly in a similar way. 

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). 

Radiation Dose - Amount of ionizing radiation energy received or absorbed by a material during exposure. Also called radiation dosage, ionizing radiation dose. 

The exposure to radiation is the product of the absorbed dose rate, which is a rate of energy absorption, and the exposure Ume. Most of the injuries listed above are of the threshold type. The dosage received must exceed a minimum before any physiological effect is observed. Above this level, small dose rates for a long period of exposure time are less injurious than an equivalent total dosage comprised of a very-high-level dose rate for a much smaller period of time. From an engineering viewpoint, the dose rate must be expressed in quantitative units as discussed next. 

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