Occupational Intakes of Radionuclides Part 1 - ICRP
Occupational Intakes of Radionuclides Part 1 - ICRP
Occupational Intakes of Radionuclides Part 1 - ICRP
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DRAFT REPORT FOR CONSULTATION<br />
by emptying in faeces. Doses are calculated for all these regions. The colon is<br />
partitioned, for the purposes <strong>of</strong> dose calculations, into right colon, left colon and<br />
rectosigmoid (the sigmoid colon and rectum) based on the availability <strong>of</strong> transit time<br />
data. The rectum is included with the sigmoid colon, as the rectosigmoid, because <strong>of</strong><br />
difficulties in determining transit times separately and because the rectum does not<br />
have a specific wT value. Total colon doses are combined as a mass-weighted mean to<br />
include the right colon, left colon and rectosigmoid.<br />
3.3.2 Model parameters<br />
(177) The HATM presents different transit times for solid foods, liquids, and total<br />
diet, in the mouth, oesophagus and stomach. First-order kinetics is assumed for all<br />
transfers in the HAT. This is a considerable simplification <strong>of</strong> the complex processes<br />
involved in transfer <strong>of</strong> material through the lumen <strong>of</strong> the alimentary tract but is<br />
expected to provide a reasonably accurate representation <strong>of</strong> the mean residence time<br />
<strong>of</strong> a radionuclide in each segment <strong>of</strong> the tract.<br />
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