Computational Dosimetry for Electron Microbeams: Monte-Carlo Track Simulation with Confocal Microscopy

Journal Article · Mon Oct 15 04:00:00 EDT 2001 · Radiation Research

OSTI ID:15006408

Miller, John H; Wilson, W E; Lynch, D J; Resat, Marianne S; Trease, Harold E

Both in vitro and in vivo experiments show that cells that do not receive energy directly from the radiation field (bystanders) respond to radiation exposure. This effect is most easily demonstrated with radiation fields composed of particles with high linear energy transfer (LET) that traverse only a few cells before they are stopped. Even at a moderate fluence of high-LET radiation only a small fraction of cells in the irradiated population are hit; hence, many bystanders are present. Low-LET radiation tends to generate a homogeneous distribution of dose at the cellular level so that identifying bystanders is much more difficult than in experiments with the same fluence of high-LET radiation. Experiments are underway at several laboratories to characterize bystander responses induced by low-LET radiation. At the Pacific Northwest National Laboratory, experiments of this type are being carried out with an electron microbeam. A cell selected to receive energy directly from the irradiation source is placed over a hole in a mask that covers an electron gun. Monte Carlo simulations by Miller et al.(1) suggest that individual mammalian cells in a confluent monolayer could be targeted for irradiation by 25 to 100 keV electrons with minimal dose leakage to their neighbors. These calculations were based on a simple model of the cellular monolayer in which cells were assumed to be cylindrically symmetric with concentric cytoplasm and nucleus. Radial profiles, the lateral extent of cytoplasm and nucleus as a function of depth into a cell, were obtained from confocal microscopy of HeLa-cell monolayers.

• Research Organization: Pacific Northwest National Lab., Richland, WA (US), Environmental Molecular Sciences Laboratory (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 15006408
• Report Number(s): PNNL-SA-34082; 2370; KP1102020
• Journal Information: Radiation Research, Journal Name: Radiation Research Journal Issue: 4 Vol. 156; ISSN 0033-7587; ISSN RAREAE
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
ANIMAL CELLS
COMPUTERIZED SIMULATION
CYTOPLASM
DOSIMETRY
ELECTRON GUNS
ENVIRONMENTAL MOLECULAR SCIENCES LABORATORY
NULL
IN VITRO
IN VIVO
IRRADIATION
LET
MAMMALS
MICROSCOPY
MONTE CARLO METHOD
RADIATION DOSES