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A Behavior of Radon and Its Decay Products in the Body
Pages 231-240

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From page 231...
... Appendixes
From page 233...
... (see also Williams and Leggett 1989; Leggett and Williams 1991~. The blood of the body is partitioned into a number of compartments, representing various blood pools in the body (the compartment Large Veins represents the venous return from the systemic tissues, Right Heart and Left Heart the content of the heart chambers, Alveolar represents the region of gas exchange in the lung, and Large Arteries represent the arterial blood flow to the systemic tissues)
From page 234...
... I Lung Tissue | Alveolar Right I \' I Left I Heart | Exhalation I Heart 1 Heart Wall FIGURE A-1 Schematic diagram of the physiologically based pharmacokinetic (PBPK) model developed to describe the fate of radon within systemic tissues.
From page 235...
... A.4 where the summation is over all perfused tissues other than the lung, Ailing is the activity of radon within the tissues of the lung (compartment Lung Tissue) , Fifing is the fraction of the cardiac output distributed to lung tissue of which only onethird enters the Large Vein compartment, Vying is the volume of lung tissue, and Vvis the volume of venous blood.
From page 236...
... Radon enters the Left Heart compartment from the Alveolar and Lung Tissue compartments and departs to Large Arteries compartment. The concentration of radon in the blood flowing from the gas-exchange region of the lung, Cp, is in equilibrium with the alveolar air; i.e., Cp = \~ Cv, where Cv is the radon concentration in alveolar air.
From page 237...
... PARAMETER VALUES Adult Values J The first-order transfer coefficients describing the movement of radon within the blood are, as indicated above, dependent on the cardiac output VcO, the distribution of the cardiac output Fi, and the tissue-to-blood partition coefficient kit The reference values for the total blood volume and cardiac output in an adult male are 5.3 L and 6.5 L mind, respectively (Leggett and Williams 1995~. The large arteries and veins in Fig A-1 contain 6 and 18% of the blood volume of the body, respectively.
From page 238...
... A-4, is 6~5 L min 1xO.OSx0~92 g cm-3 xlO3cm3 L 12.5 kgx103g kg 1 x11.2 - = 2.14xlO 3 min 1 A.10 where all numerical values are from tables A-1 and A-2. The biological removal from adipose tissue corresponds to a half-time, in the absence of additional input, of about 5.4 hours.
From page 239...
... Pi Stomach Wall 0.15 1.05 Kidneys 0.31 1.05 Small Intestine Wall 0.64 1.04 Muscle 28.0 1.04 Upper Large Intestine Wall 0.21 1.04 Red Marrow 1.5 1.03 Lower Large Intestine Wall 0.16 1.04 Yellow Marrow 1.5 0.98 Pancreas 0.10 1.05 Trabecular Bone 1.0 1.92 Spleen 0.18 1.05 Cortical Bone 4.0 1.99 Adrenals 0.014 1.02 Adipose Tissue 12.5 0.92 Brain 1.4 1.03 Skin 2.6 1.05 Heart Wall 0.33 1.03 Thyroid 0.02 1.05 Liver 1.8 1.04 Testes 0.035 1.04 Lung Tissue 0.47 1.05 Other 3.2 1.04 The response of the model was shown graphically in chapter 4 and compared to experimental observations. Other Ages Considerably less information is available regarding cardiac output and blood volumes in the non-adult.
From page 240...
... have assessed the component of the dose associated with decay products from within the body following the intake of a radionuclide based on the biokinetic behavior of the specific decay product; so-called independent kinetics. Details regarding this implementation are discussed in Annex C of Publication 71 (ICRP 1995~.


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