Nanodosimetry in a clinical neutron therapy beam using the variance-covariance method and Monte Carlo simulations.

• Nanodosimetric single-event distributions or their mean values may contribute to a better understanding of how radiation induced biological damages are produced. They may also provide means for radiation quality characterization in therapy beams. Experimental nanodosimetry is however technically challenging and Monte Carlo simulations are valuable as a complementary tool for such investigations. The dose-mean lineal energy was determined in a therapeutic p(65)+Be neutron beam and in a Co-60 gamma. beam using low-pressure gas detectors and the variance-covariance method. The neutron beam was simulated using the condensed history Monte Carlo codes MCNPX and SHIELD-HIT. The dose-mean lineal energy was calculated using the simulated dose and fluence spectra together with published data from track-structure simulations. A comparison between simulated and measured results revealed some systematic differences and different dependencies on the simulated object size. The results show that both experimental and theoretical approaches are needed for an accurate dosimetry in the nanometer region. In line with previously reported results, the dose-mean lineal energy determined at 10 nm was shown to be related to clinical RBE values in the neutron beam and in a simulated 175 MeV proton beam as well.

Subject headings

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Keyword

Computer Simulation

Models; Biological

Models; Statistical

Monte Carlo Method

Nanotechnology/*methods

Neutron Capture Therapy/*methods

Radiometry/*methods

Radiotherapy Dosage

Regression Analysis

Reproducibility of Results

Sensitivity and Specificity

Physics

Fysik

MEDICINE

Publication and Content Type

vet (subject category)

art (subject category)