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Monte Carlo calculations of absorbed doses in tumours using a modified MOBY mouse phantom for pre-clinical dosimetry studies.

Larsson, Erik LU ; Ljungberg, Michael LU ; Strand, Sven-Erik LU and Jönsson, Bo-Anders LU (2011) In Acta oncologica (Stockholm, Sweden) 50(6). p.973-980
Abstract
Abstract Background. Clinical treatment with radionuclides is usually preceded by biokinetic and dosimetry studies in small animals. Evaluation of the therapeutic efficacy is essential and must rely on accurate dosimetry, which in turn must be based on a realistic geometrical model that properly describes the transport of radiation. It is also important to include the source distribution in the dosimetry calculations. Tumours are often implanted subcutaneously in animals, constituting an important additional source of radiation that often is not considered in the dosimetry models. The aims of this study were to calculate S values of the mouse, and determine the absorbed dose contribution to and from subcutaneous tumours inoculated at four... (More)
Abstract Background. Clinical treatment with radionuclides is usually preceded by biokinetic and dosimetry studies in small animals. Evaluation of the therapeutic efficacy is essential and must rely on accurate dosimetry, which in turn must be based on a realistic geometrical model that properly describes the transport of radiation. It is also important to include the source distribution in the dosimetry calculations. Tumours are often implanted subcutaneously in animals, constituting an important additional source of radiation that often is not considered in the dosimetry models. The aims of this study were to calculate S values of the mouse, and determine the absorbed dose contribution to and from subcutaneous tumours inoculated at four different locations. Methods. The Moby computer program generates a three dimensional (3D) voxel-based phantom. Tumours were modelled as half-spheres on the body surface, and the radius was varied to study different tumour masses. The phantoms were used as input for Monte Carlo simulations of absorbed fractions and S factors with the radiation transport code MCNPX 2.6f. Calculations were performed for monoenergetic photons and electrons, and the radionuclides (125)I, (131)I, (111)In, (177)Lu and (90)Y. Results. Electron energy and tumour size are important for both self- and cross-doses. If the activity is non-uniformly distributed within the body, the position of the tumour must be considered in order to calculate the tumour absorbed dose accurately. If the uptake in the tumour is high compared with that in adjacent organs the absorbed dose contribution to organs from the tumour cannot be neglected. Conclusions. In order to perform accurate tumour dosimetry in mouse models it is necessary to take the additional contribution from the activity distribution within the body of the mouse into account. This may be of significance in the interpretation of radiobiological tumour response in pre-clinical studies. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Acta oncologica (Stockholm, Sweden)
volume
50
issue
6
pages
973 - 980
publisher
Taylor & Francis
external identifiers
  • wos:000292841500031
  • pmid:21767199
  • scopus:79960512423
ISSN
1651-226X
DOI
10.3109/0284186X.2011.582517
language
English
LU publication?
yes
id
dab1cefb-73f8-42ab-9f2f-f131070139b3 (old id 2058534)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/21767199?dopt=Abstract
date added to LUP
2011-08-01 12:51:38
date last changed
2017-05-21 04:40:17
@article{dab1cefb-73f8-42ab-9f2f-f131070139b3,
  abstract     = {Abstract Background. Clinical treatment with radionuclides is usually preceded by biokinetic and dosimetry studies in small animals. Evaluation of the therapeutic efficacy is essential and must rely on accurate dosimetry, which in turn must be based on a realistic geometrical model that properly describes the transport of radiation. It is also important to include the source distribution in the dosimetry calculations. Tumours are often implanted subcutaneously in animals, constituting an important additional source of radiation that often is not considered in the dosimetry models. The aims of this study were to calculate S values of the mouse, and determine the absorbed dose contribution to and from subcutaneous tumours inoculated at four different locations. Methods. The Moby computer program generates a three dimensional (3D) voxel-based phantom. Tumours were modelled as half-spheres on the body surface, and the radius was varied to study different tumour masses. The phantoms were used as input for Monte Carlo simulations of absorbed fractions and S factors with the radiation transport code MCNPX 2.6f. Calculations were performed for monoenergetic photons and electrons, and the radionuclides (125)I, (131)I, (111)In, (177)Lu and (90)Y. Results. Electron energy and tumour size are important for both self- and cross-doses. If the activity is non-uniformly distributed within the body, the position of the tumour must be considered in order to calculate the tumour absorbed dose accurately. If the uptake in the tumour is high compared with that in adjacent organs the absorbed dose contribution to organs from the tumour cannot be neglected. Conclusions. In order to perform accurate tumour dosimetry in mouse models it is necessary to take the additional contribution from the activity distribution within the body of the mouse into account. This may be of significance in the interpretation of radiobiological tumour response in pre-clinical studies.},
  author       = {Larsson, Erik and Ljungberg, Michael and Strand, Sven-Erik and Jönsson, Bo-Anders},
  issn         = {1651-226X},
  language     = {eng},
  number       = {6},
  pages        = {973--980},
  publisher    = {Taylor & Francis},
  series       = {Acta oncologica (Stockholm, Sweden)},
  title        = {Monte Carlo calculations of absorbed doses in tumours using a modified MOBY mouse phantom for pre-clinical dosimetry studies.},
  url          = {http://dx.doi.org/10.3109/0284186X.2011.582517},
  volume       = {50},
  year         = {2011},
}