0000000000591401
AUTHOR
Tobias Schmitz
Dose calculation in biological samples in a mixed neutron-gamma field at the TRIGA reactor of the University of Mainz
To establish Boron Neutron Capture Therapy (BNCT) for non-resectable liver metastases and for in vitro experiments at the TRIGA Mark II reactor at the University of Mainz, Germany, it is necessary to have a reliable dose monitoring system. The in vitro experiments are used to determine the relative biological effectiveness (RBE) of liver and cancer cells in our mixed neutron and gamma fi eld. We work with alanine detectors in combination with Monte Carlo simulations, where we can measure and characterize the dose. To verify our calculations we perform neutron fl ux measurements using gold foil activation and pin-diodes . Material and methods . When L- α -alanine is irradiated with ionizing …
Dose determination using alanine detectors in a mixed neutron and gamma field for boron neutron capture therapy of liver malignancies
IntroductionBoron Neutron Capture Therapy for liver malignancies is being investigated at the University of Mainz. One important aim is the set-up of a reliable dosimetry system. Alanine dosimeters have previously been applied for dosimetry of mixed radiation fields in antiproton therapy, and may be suitable for measurements in mixed neutron and gamma fields.Materials and MethodsTwo experiments have been carried out in the thermal column of the TRIGA Mark II reactor at the University of Mainz. Alanine dosimeters have been irradiated in a phantom and in liver tissue.ResultsFor the interpretation and prediction of the dose for each pellet, beside the results of the measurements, calculations …
The alanine detector in BNCT dosimetry: Dose response in thermal and epithermal neutron fields
Purpose: The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed. Methods: Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secon…
Determination of boron concentration in blood and tissue samples from patients with liver metastases of colorectal carcinoma using Prompt Gamma Ray Activation Analysis (PGAA).
As part of the studies on Boron Neutron Capture Therapy at the University of Mainz, Germany, a clinical trial has been started, in which our patients suffering from liver metastases of colorectal carcinoma, have been enrolled. Specimens of blood and healthy tissue samples taken from the patients were measured at the PGAA facilities at the HFR in Petten, The Netherlands, and at the FRM II in Munich, Germany. From the measured boron concentrations, pharmacokinetic curves and blood-to-tissue concentration ratios were produced.
Confirmation of a realistic reactor model for BNCT dosimetry at the TRIGA Mainz
Purpose: In order to build up a reliable dose monitoring system for boron neutron capture therapy (BNCT) applications at the TRIGA reactor in Mainz, a computer model for the entire reactor was established, simulating the radiation field by means of the Monte Carlo method. The impact of different source definition techniques was compared and the model was validated by experimental fluence and dose determinations. Methods: The depletion calculation code ORIGEN2 was used to compute the burn-up and relevant material composition of each burned fuel element from the day of first reactor operation to its current core. The material composition of the current core was used in a MCNP5 model of the in…
Adaption of a PIN-diode detector as an online neutron monitor for the thermal column of the TRIGA research reactor.
A BNCT online neutron monitoring system was tested in a TRIGA reactor, using a silicon PIN-diode with a conversion foil. The setup was tested with different reactor powers at the hot and cold ends of the irradiation channel, using activation foils to compare with measured fluxes. The results demonstrate good reproducibility and show a linear correlation between signal of the PIN-diode and neutron flux at all positions, demonstrating this approach to be suitable for online monitoring of the neutron flux.
The FiR 1 photon beam model adjustment according to in-air spectrum measurements with the Mg(Ar) ionization chamber.
Abstract The mixed neutron–photon beam of FiR 1 reactor is used for boron–neutron capture therapy (BNCT) in Finland. A beam model has been defined for patient treatment planning and dosimetric calculations. The neutron beam model has been validated with an activation foil measurements. The photon beam model has not been thoroughly validated against measurements, due to the fact that the beam photon dose rate is low, at most only 2% of the total weighted patient dose at FiR 1. However, improvement of the photon dose detection accuracy is worthwhile, since the beam photon dose is of concern in the beam dosimetry. In this study, we have performed ionization chamber measurements with multiple b…