Search results for "Physics::Medical Physics"

Determination of the irradiation field at the research reactor TRIGA Mainz for BNCT.

2009

For the application of the BNCT for the excorporal treatment of organs at the TRIGA Mainz, the basic characteristics of the radiation field in the thermal column as beam geometry, neutron and gamma ray energies, angular distributions, neutron flux, as well as absorbed gamma and neutron doses must be determined in a reproducible way. To determine the mixed irradiation field thermoluminescence detectors (TLD) made of CaF(2):Tm with a newly developed energy-compensation filter system and LiF:Mg,Ti materials with different (6)Li concentrations and different thicknesses as well as thin gold foils were used.

Elastic scattering studies of 16C at 50 MeV/A on proton and deuteron targets with the CHIMERA multidetector at INFN-LNS

2012

At the Laboratori Nazionali del Sud (LNS) in Catania (Italy), light radioactive ion beams have been produced through the In Flight Fragmentation method, using 18O and 13C at 55 MeV/A as primary beams impinging on a 9Be production target. Elastic scattering angular distributions of 16C+p and 16C+d at 50 MeV/A, 10Be+p at 56 MeV/A and 13B+d at 52 MeV/A systems were measured by using the CHIMERA (Charge Heavy Ion Mass and Energy Resolving Array) multidetector and kinematical coincidence technique. The experimental data are fitted by using the optical model. © Published under licence by IOP Publishing Ltd.

Inter/intramolecular Cherenkov radiation energy transfer (CRET) from a fluorophore with a built-in radionuclide.

2014

The Cherenkov radiation (CR) from [(18)F]-FDG, [(177)Lu]-LuCl3 and [(90)Y]-YCl3 was detected and CR energy transfer (CRET) to several fluorophores was examined. Subsequent fluorescence emission was found to be a function of the position of absorption bands with respect to the CR peak, energy of emitted particles, radionuclide/fluorophore loading, and fluorophore brightness. A variant of the best fluorophore with a built-in radionuclide was synthesized to achieve inter- and intra-molecular CRET.

Color centers and structural damage in LiF induced by 150 MeV Kr ions

2012

Color centers and evolution of structure defects were investigated in LiF crystals irradiated at room temperature with 150 MeV 84Kr ions with a beam current of 10nA/cm2 in the fluence range 1011 - 1014 ions/cm2 at the cyclotron accelerator DC-60 (Astana, Kazakhstan). At the fluence of 1011 ions/cm2, SEM imaging revealed mainly formation of etchable ion tracks. Above this fluence, severe structural modifications in the irradiated layer were observed which include the ion-induced formation of dislocations and grains with nano-scale dimensions. The role of fluence in the concentration of electronic color centers and structural modifications is discussed.

AX-PET: A novel PET detector concept with full 3D reconstruction

2009

We describe the concept and first experimental tests of a novel 3D axial Positron Emission Tomography (PET) geometry. It allows for a new way of measuring the interaction point in the detector with very high precision. It is based on a matrix of long Lutetium-Yttrium OxyorthoSilicate (LYSO) crystals oriented in the axial direction, each coupled to one Geiger Mode Avalanche Photodiode (G-APD) array. To derive the axial coordinate, Wave Length Shifter (WLS) strips are mounted orthogonally and interleaved between the crystals. The light from the WLS strips is read by custom-made G-APDs. The weighted mean of the signals in the WLS strips has proven to give very precise axial resolution. The ach…

Imaging of Located Buried Defects in Metal Samples by an Scanning Microwave Microscopy

2011

Abstract A non-destructive method is proposed to detect the located buried defects using scanning microwave microscopy. Based on the “skin effect”, our recent developments authorize 3D tomography with nanometric resolution. This technique associates the electromagnetic microwave measurement using a Vector Network Analyzer (VNA) with the nanometer-resolution positioning capabilities of an Atomic Force Microscope. At each used frequency, an incident electromagnetic wave is send to the sample and the reflected wave gives information on a specific depth layer in the material. With a large bandwidth of frequencies, a 3D tomography is allowed inside the material. With characteristic tools of nano…

EP-1590: Shielding design and fetal dose evaluation of a breast cancer pregnant patient undergoing HDR Ir-192 brachytherapy

2015

Magnetic resonance image segmentation and heart motion tracking with an active mesh based system

2002

International audience; Abstract: The work presented here relates to a method fir motion tracking in sequences of medical images. The purpose is to. quantify the general motions and the local deformations of a beating heart during a cardiac cycle. In order to achieve this goal, we first tessellate the,first image of the sequence into triangular patches. A Delaunay triangulation is applied to find the optimal set of triangles describing this image, giving a mesh covering the organs. One imposes the contours of the organs to correspond to edges of triangles so that each part of the heart (left ventricle, right ventricle, myocardium) can he described as a different set of triai izles, each set…

Correction factors for ionization chamber measurements with the ‘Valencia’ and ‘large field Valencia’ brachytherapy applicators

2018

Treatment of small skin lesions using HDR brachytherapy applicators is a widely used technique. The shielded applicators currently available in clinical practice are based on a tungsten-alloy cup that collimates the source-emitted radiation into a small region, hence protecting nearby tissues. The goal of this manuscript is to evaluate the correction factors required for dose measurements with a plane-parallel ionization chamber typically used in clinical brachytherapy for the 'Valencia' and 'large field Valencia' shielded applicators. Monte Carlo simulations have been performed using the PENELOPE-2014 system to determine the absorbed dose deposited in a water phantom and in the chamber act…

Solar Surface Magnetism and Irradiance on Time Scales from Days to the 11-Year Cycle

2009

The uninterrupted measurement of the total solar irradiance during the last three solar cycles and an increasing amount of solar spectral irradiance measurements as well as solar imaging observations (magnetograms and photometric data) have stimulated the development of models attributing irradiance variations to solar surface magnetism. Here we review the current status of solar irradiance measurements and modelling efforts based on solar photospheric magnetic fields. Thereby we restrict ourselves to the study of solar variations from days to the solar cycle. Phenomenological models of the solar atmosphere in combination with imaging observations of solar electromagnetic radiation and meas…