Ionization Detail Parameters for DNA Damage Evaluation in Charged Particle Radiotherapy: Simulation Study Based on Cell Survival Database.

Details of excitation and ionization acts hide a description of the biological effects of charged particle traversal through living tissue. Nanodosimetry enables the introduction of novel quantities that characterize and quantify the particle track structure while also serving as a foundation for assessing biological effects based on this quantification. This presents an opportunity to enhance the planning of charged particle radiotherapy by taking into account the ionization detail.

Modeling of dose and linear energy transfer homogeneity in cell nuclei exposed to alpha particles under various setup conditions.

Purpose: Different alpha exposure setups are often used to study the relation between biological responses and LET. This study aimed to estimate the dose heterogeneity and uncertainty in four exposure setups using Geant4 and PARTRAC codes. The importance of the irradiation system characteristics was shown in the context of reporting experimental results, especially in radiobiological studies at the molecular level.

Intercomparison of nanodosimetric distributions in nitrogen simulated with Geant4 and PTra track structure codes.

To facilitate the use of Geant4-DNA for radiation transport simulations in micro- and nanodosimeters, which are physically operated with tissue-equivalent gases such as nitrogen (and propane), this work aims to extend the cross section data available in Geant4-DNA to include those of nitrogen for electron energies ranging from 1 MeV down to the ionisation threshold. To achieve this, interaction cross section data for nitrogen that have been used with the in-house PTB PTra track structure code have been implemented in the current state-of-the-art Geant4-DNA simulation toolkit. An intercomparison has been performed between the two codes to validate this implementation.

Geant4-DNA modeling of nanodosimetric quantities in the Jet Counter for alpha particles.

The purpose of this work was to validate the calculation accuracy of nanodosimetric quantities in Geant4-DNA track structure simulation code. We implemented the Jet Counter (JC) nanodosimeter geometry in the simulation platform and quantified the impact of the Geant4-DNA physics models and JC detector performance on the ionization cluster size distributions (ICSD). ICSD parameters characterize the quality of radiation field and are supposed to be correlated to the complexity of the initial DNA damage in nanoscale and eventually the response of biological systems to radiation.

Event-related potentials in the odd-ball paradigm and behavioral scales for the assessment of children and adolescents with disorders of consciousness: A proof of concept study.

Objective: Quantification of signatures of conscious processing in children with disorders of consciousness (DoC) using odd-ball paradigms in multiple modalities.

Method: We review the diagnostic approaches available in the field, from clinical scales to neuroimaging methods, and concentrate upon measures derived from electroencephalographic event related potentials.

Results: Evoked potentials were recorded in five procedures, encompassing visual, auditory and tactile modalities, from ten pediatric DoC patients-six in a minimally conscious state (MCS), three in unresponsive wakefulness syndrome (UWS) and one who emerged from MCS (eMCS)-and the control group of 10 healthy children.

Parametric Description of EEG Profiles for Assessment of Sleep Architecture in Disorders of Consciousness.

We propose a fully parametric approach to the assessment of sleep architecture, based upon the classical electroencephalographic criteria, applicable also to the recordings of patients with disorders of consciousness (DOC). Sleep spindles and slow waves are automatically detected from the matching pursuit decomposition of overnight EEG recordings. Their evolution can be presented in the form of EEG profiles, yielding a continuous description of sleep architecture, compatible with the classical criteria used in sleep staging.

Assessment of Statistically Significant Command-Following in Pediatric Patients with Disorders of Consciousness, Based on Visual, Auditory and Tactile Event-Related Potentials.

Disorders of consciousness (DOC) are among the major challenges of contemporary medicine, mostly due to the high rates of misdiagnoses in clinical assessment, based on behavioral scales. This turns our attention to potentially objective neuroimaging methods. Paradigms based on electroencephalography (EEG) are most suited for bedside applications, but sensitive to artifacts.

ON THE TWO MODES OF NANODOSIMETRIC EXPERIMENT.

A method of estimation of the ionisation cluster-size distribution for single primary particle from experimental data obtained in setup without primary particle detector is presented. The Jet Counter nanodosemeter was used in two kinds of experiments with alpha particles to validate the method. Possible application of the method is to perform measurements with previously precluded types of radiation like photons, neutrons and electrons.

MEASUREMENTS OF SPATIAL CORRELATIONS OF IONISATION CLUSTERS IN THE TRACK OF CARBON IONS-FIRST RESULTS.

An attempt towards an experimental set up which could provide the experimental data on correlation processes occurred simultaneously in two distanced DNA targets within a charged particle track is presented. A modified Jet Counter nanodosemeter was used in two experiments with carbon ions with mean energies of 52 and 23 MeV. The probability distributions of the correlated pairs of ionisation clusters produced in two neighbouring sensitive volumes are presented.

Status report: Nanodosimetry of carbon ion beam at HIL.

We present preliminary data for measured distributions of ionization cluster size produced by carbon ions in tissue equivalent media. The experiments were carried out with a beam of 92 MeV carbon ions from the U200p cyclotron at the Heavy Ion Laboratory (HIL), University of Warsaw, and nitrogen targets using the so-called Jet Counter set-up.