Radiation dosage units

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

A unit of radiation dosage that accounts for both the energy of the dose and its effectiveness in causing biological damage... 

Reduction a decrease in oxidation state (a gain of electrons). (4.9 17.1) Rem a unit of radiation dosage that accounts for both the energy of the dose and its effectiveness in causing biological damage (from roentgen equivalent for man). (19.7)... 

Knowing how many disintegrations per unit time occur in a radioactive sample, or the number of ionizations in a volume of air, are not very helpful in characterizing the effects of radiation on human tissue and therefore the rad and the rem are commonly used to measure radiation dosage. Table 10-4 lists the types of radiation units, and the situations in which they are appropriately applied. A rad of a-rays will produce more damage than a rad of /3-rays. 

Three noteworthy trends are apparent in the current use of highly crosslinked UHMWPE for THA, at least in the United States. These trends relate to the overall acceptance of the technology, the prevalence of gamma radiation as a crosslinking modality, and the prevalence of elevated radiation dosages for crosslinking. 

Compare different measurements and units of radiation dosage. (Section 21.9)... 

It has been remarked above that electron microscopy produces a large radiation dose in the specimen. The standard unit of radiation dosage used from 1959 until recently, was the rad. This is defined as the absorption of 100 erg of energy from ionizing radiation per gram of material irradiated. This unit of absorbed dose is used because usually the chemical effect of radiation depends only on the absorbed energy per unit mass. It is independent of the type of radiation or its rate of application. 

Rem a unit of radiation dosage used to relate various kinds of radiation in terms of biological destruction. It equals the rad times a factor for the type of radiation, called the relative biological effectiveness (RBE) rems = rads X RBE. (213)... 

Explain why the rem is more satisfactory than the rad as a unit for measuring radiation dosage. 

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). 

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