Collective effective dose equivalent

Table 3.3 summarizes the radiation exposure doses due to the industrial exploitation of phosphate rock, expressed in terms of collective effective dose equivalent commitments resulting from the decision to use a unit mass of marketable ore to accomplish a defined purpose, as reported by UN Scientific Committee on Effects of Atomic Radiation (United Nations, 1982). 

Collective effective dose equivalent commitments per unit of marketable phosphate ore (10 man Sv t" )... 

Although during normal operation of research reactors exposure of the public due to the release of radioactive materials in the environment is expected to be negligible, a site-related assessment of such exposure should be performed prior to operation. The main objective of this assessment is to demonstrate compliance with the system of dose limitation as described in detail in IAEA Safety Series No. 9 "Basic Safety Standards for Radiation Protection 13). These evaluations are normally required by regulatory authorities and include estimating the effective dose equivalent for the most exposed members of the public (critical group) and collective effective dose equivalent commitment of the population ("collective dose"). 

The collective dose quantity represents the total consequences of exposures of a population or group. The use should be limited to situations in which the consequences are truly proportional to both the dosimetric quantity and the number of people exposed. The collective equivalent dose, Sr, is the average dose to a tissue or organ T in the exposed group multiplied by the number of individuals in the group. If several groups are involved, the total collective quantity is the sum of the collective quantities for each group. The collective effective dose, S, has similarly been defined by ICRP ... 

Table 2.11. Collective effective equivalent doses over 50 a (Clarke, 1987)...

Radiotoxicity depends on energy deposition in tissue or organs by the radionuclide, the specific tissue exposed to the radionuclide, and the tissue radiation sensitivity. Energy deposition by a radionuclide is a function of its emitted radiations and half-life. Biokinetic studies have identified for most radionuclides of interest the pattern of movement through the body and the effective turnover rate (the sum of the biological and radioactive turnover rates). Biokinetic information also identifies the appropriate type of sample to be collected among blood, urine, feces, saliva, breath, hair, teeth, nasal swipes, and tissue obtained incidental to unrelated operations, and collection frequency. The measured radionuclide concentrations are combined with biokinetic information to calculate the committed dose equivalent, the indicator of radiation impact on the subject (NCRP 1987b). 

In general, to assess the delayed effects of current exposure, dose quantities of the ionizing radiations are introduced. The term dose is used in a general sense as a measure of the quantity of radiation or the energy deposited by radiation in a target. For the strictest use in dosimetry, the term must be specified as absorbed dose, equivalent dose, organ dose, etc. These quantities may refer to exposed individuals (individual dose) or to a group of people (collective dose). 

The SI unit of committed effective dose is Sv, the same as for effective dose. Similarly, one can derive a committed equivalent dose. The quantity of dose commitment differs from the committed dose only by the upper integration limit. It is defined as the infinite time integral (t = oo) of the per caput dose rate Hi or E) ofthe population due to a specified event. The unit of the dose commitment is the same as for committed dose. Both individual dose commitment and collective dose commitment can be defined. 

A dose of 1 pg desmopressin acetate has antidiuretic activity that is equivalent to 4U arginine vasopressin. Desmopressin acetate has recently been evaluated in normal horses. The author and coworkers diluted desmopressin acetate (0.1 mg/ml) nasal spray in sterile water and administered 0.05pg/kg i.v. (25 pg, equivalent to 100 U of antidiuretic activity in a 500 kg horse) to horses with polyuria induced by repeated nasogastric intubation of water for 3 days. Urine was collected for 8h after desmopressin acetate administration and there was an increase in urine specific gravity to >1.020 from 2 to 7h after administration (Fig. 10.2). The drug had no effects on heart rate or systemic blood pressure. These preliminary data demonstrate that the i.v. administration of desmopressin acetate appears to be safe and a useful tool for the evaluation of horses with DI. 

The ACC/AHA guidelines, developed before the Val-HeFT, CHARM, and VALIANT trials were completed, indicate that ARBs should not be considered equivalent or superior to ACE inhibitors and that they should be considered in patients who are intolerant of ACE inhibitors. Collectively, the results of these trials clearly support this recommendation. Eor patients unable to tolerate an ACE inhibitor, usually due to intractable cough or angioedema, an ARB is a safe and effective alternative, although caution stiU should be exercised when it is used in patients with angioedema from ACE inhibitors. ARBs are not an alternative in patients with hypotension, hyperkalemia, or renal insufficiency secondary to ACE inhibitors because they are as likely to cause these adverse effects. The specific drugs and doses proven to be effective in chnical trials should be used. The role of ARBs as an adjunct to ACE inhibitors remains controversial. 

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