COMPUTATIONAL METHODS IN RADIONUCLIDE DOSIMETRY

Citation
M. Bardies et Mj. Myers, COMPUTATIONAL METHODS IN RADIONUCLIDE DOSIMETRY, Physics in medicine and biology, 41(10), 1996, pp. 1941-1955
Citations number
130
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging
ISSN journal
00319155
Volume
41
Issue
10
Year of publication
1996
Pages
1941 - 1955
Database
ISI
SICI code
0031-9155(1996)41:10<1941:CMIRD>2.0.ZU;2-C
Abstract
The various approaches in radionuclide dosimetry depend on the size an d spatial relation of the sources and targets considered in conjunctio n with the emission range of the radionuclide used. We present some of the frequently reported computational techniques on the basis of the source/target size. For whole organs, or for sources or targets bigger than some centimetres, the acknowledged standard was introduced 30 ye ars ago by the MIRD committee and is still being updated. That approac h, based on the absorbed fraction concept, is mainly used for radiopro tection purposes but has been updated to take into account the dosimet ric challenge raised by therapeutic use of vectored radiopharmaceutica ls. At this level, the most important computational effort is in the f ield of photon dosimetry. On the millimetre scale, photons can often b e disregarded, and beta or electron dosimetry is generally reported. H eterogeneities at this level are mainly above the cell level, involvin g groups of cell or a part of an organ. The dose distribution pattern is often calculated by generalizing a point source dose distribution, but direct calculation by Monte Carlo techniques is also frequently re ported because it allows media of inhomogeneous density to be consider ed. At the cell level, alpha and electron (low-range beta or Auger) ar e the predominant emissions examined. Heterogeneities in the dose dist ribution are taken into account, mainly to determine the mean dose at the nucleus. At the DNA level, Auger electrons or alpha-particles are considered from a microdosimetric point of view. These studies are oft en connected with radiobiological experiments on radionuclide toxicity .