Biomedical subjects

A A Kuronen

Publications and source records attributed to A A Kuronen.

3 recordsLinked to original sources

PubMed2001

Comparison of different cell-cluster models for cell-level dosimetry.

An important factor in dose calculations for targeted radionuclide therapy is the cell-cluster model used. We developed a cell-cluster model based on optimization through mechanical hard-sphere collisions. The geometrical properties and the dosimetric effects of the new model were compared with those of two previous models, i.e. the traditional lattice model and our CellPacker model in which the cells are individually and systematically piled as a cluster. The choice of the cell-cluster model has an effect on the calculated mean absorbed doses in the cells. While CellPacker produces clusters with distinct tumour-healthy tissue interface, our new model is able to make the interface diffuse. Outside the interface the new model is capable to pack cells tighter than CellPacker enabling the description of tissues of higher cellular density. Our two cluster models make it possible to construct the cluster model according to the tissue in question.

Cell Aggregation↗

PubMed2000

Radiation spectra of 111In, 113mIn and 114mIn.

The radiation spectra of 111In, 113In, and 114mIn are calculated with the Monte Carlo computer program IMRDEC. The relaxation probabilities are taken from the EADL file of the Lawrence Livermore National Laboratory. Because this file does not include data for some N and O transitions, these were additionally determined by applying the Kassis rule. Two schemes are applied to calculate the transition energies: 1) a simple (Z + 1)/Z scheme, and 2) accurate calculation solving the relativistic Dirac equations. It is shown that using the extended set of relaxation probabilities leads to generation of many additional low-energy Auger and CK electrons if the (Z + 1)/Z rule is applied. On the other hand, the emissions of almost all these electrons are rejected if their energies are calculated solving the Dirac equations taking into consideration realistic electron vacancies.

Biophysical Phenomena↗

PubMed1999

Cluster models in cellular level electron dose calculations.

A program for calculating absorbed dose was developed for radioimmunotherapy (RIT) purposes. It was used to determine the difference in the therapeutic effect of (111)In electrons when using a close-packed cubic geometry and a cell cluster model developed in this project. Our cluster model piles the cells individually. The cells were modelled as spheres of diameters of 12 (tumour) and 30 (healthy) microm. Both models were used to generate clusters with spherical tumours inside healthy tissue. The program uses Monte Carlo-based dose kernels. The radiation spectra were calculated from the Auger and x-ray transition strengths and fluorescence yields of (111)In. The results show the importance of the cluster model in cellular level dose calculations. Near the tumour/healthy tissue interface in particular, the doses differ because of geometrical differences. In the case of a small cluster with tumour and total diameters of 30 and 150 microm, the ratio of the therapeutic effects is 20.

Absorption↗