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 />
Inactive (bone) marrow<br />
In contrast to the active marrow, the inactive marrow is haematopoietically<br />
inactive (i.e. does not directly support haematopoiesis). It gets its yellow<br />
colour from fat cells (adipocytes) which occupy most <strong>of</strong> the space <strong>of</strong> the<br />
yellow bone marrow framework.<br />
Marrow cellularity<br />
The fraction <strong>of</strong> bone marrow volume in a given bone that is<br />
haematopoietically active. Age- and bone-site-dependent reference values for<br />
marrow cellularity are given in Table 41 <strong>of</strong> <strong>ICRP</strong> Publication 70 (<strong>ICRP</strong>,<br />
1995). As a first approximation, marrow cellularity may be thought <strong>of</strong> as 1<br />
minus the fat fraction <strong>of</strong> bone marrow.<br />
Mean absorbed dose in an organ or tissue , DT<br />
The mean absorbed dose in a specified organ or tissue T is given by<br />
DT = 1/mT ∫ D dm, where mT is the mass <strong>of</strong> the organ or tissue, and D is the<br />
absorbed dose in the mass element dm. The unit <strong>of</strong> mean absorbed dose is<br />
joule per kilogram (J kg -1 ), and its special name is gray (Gy).<br />
<strong>Occupational</strong> exposure<br />
The radiation exposure <strong>of</strong> workers incurred as a result <strong>of</strong> their work. The<br />
<strong>ICRP</strong> limits its use <strong>of</strong> ‘occupational exposures’ to radiation exposures<br />
incurred at work as a result <strong>of</strong> situations that can reasonably be regarded as<br />
being the responsibility <strong>of</strong> the operating management.<br />
Organ absorbed dose. See ‘Mean absorbed dose’<br />
Short phrase for “mean absorbed dose in an organ or tissue”.<br />
Organ equivalent dose. See ‘Equivalent Dose’.<br />
Short phrase for “equivalent dose in an organ or tissue”.<br />
Protection Quantities<br />
Values that <strong>ICRP</strong> has developed for radiological protection that allow<br />
quantification <strong>of</strong> the extent <strong>of</strong> exposure to ionising radiation from both whole<br />
and partial body external irradiation and from intakes <strong>of</strong> radionuclides.<br />
Radiation weighting factor, wR<br />
A dimensionless factor by which the organ or tissue absorbed dose is<br />
multiplied to reflect the relative biological effectiveness <strong>of</strong> high-LET<br />
radiations compared to photon radiations. It is used to derive the equivalent<br />
dose from the mean absorbed dose in an organ or tissue.<br />
Red (bone) marrow<br />
See ‘Active (bone) marrow’.<br />
Response function<br />
See ‘Dose–response function’.<br />
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