Multifractal characterization of the Coniacian-Santonian OAE3 in lacustrine and marine deposits based on spectral gamma ray logs.

Limited to the Atlantic and its surrounding basins, the expression of the Coniacian-Santonian oceanic anoxic event (OAE3) was discovered in the non-marine Cretaceous Songliao Basin, Eastern Asia not long ago. In this study, based on spectral gamma ray logs data recorded in three basins, the self-similarity of the OAE3 was studied through the analysis of the scaling properties of thorium-potassium and thorium-uranium distributions both in marine and terrestrial environments using the multifractal detrending fluctuation analysis. The results indicate that, in both marine and terrestrial systems, the OAE3 intervals are characterized by their multifractal nature due to long-range correlation.

Comparison between 2D and 3D dosimetry protocols in 90Y-ibritumomab tiuxetan radioimmunotherapy of patients with non-Hodgkin's lymphoma.

Unlabelled: We compared the radiation-absorbed dose obtained from a two dimensional (2D) protocol, based on planar whole-body (WB) scans and fixed reference organ masses with dose estimates, using a 3D single-photon emission computed tomography (SPECT) imaging protocol and patient-specific organ masses.

Methods: Six (6) patients with follicular non-Hodgkin's lymphoma underwent a computed tomography (CT) scan, 5 2D planar WB, and 5 SPECT scans between days 0 and 6 after the injection of (111)In-ibritumomab tiuxetan. The activity values in the liver, spleen, and kidneys were calculated from the 2D WB scans, and also from the 3D SPECT images reconstructed, using quantitative image processing.

Validation of the Monte Carlo simulator GATE for indium-111 imaging.

Monte Carlo simulations are useful for optimizing and assessing single photon emission computed tomography (SPECT) protocols, especially when aiming at measuring quantitative parameters from SPECT images. Before Monte Carlo simulated data can be trusted, the simulation model must be validated. The purpose of this work was to validate the use of GATE, a new Monte Carlo simulation platform based on GEANT4, for modelling indium-111 SPECT data, the quantification of which is of foremost importance for dosimetric studies.

GATE: a simulation toolkit for PET and SPECT.

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics.

Voxeldoes: a computer program for 3-D dose calculation in therapeutic nuclear medicine.

A computer program, VoxelDose, was developed to calculate patient specific 3-D-dose maps at the voxel level. The 3-D dose map is derived in three steps: (i) The SPECT acquisitions are reconstructed using a filtered back projection method, with correction for attenuation and scatter; (ii) the 3-D cumulated activity map is generated by integrating the SPECT data; and (iii) a 3-D dose map is computed by convolution (using the Fourier Transform) of the cumulated activity map and corresponding MIRD voxel S values. To validate the VoxelDose software, a Liqui-Phil abdominal phantom with four simulated organ inserts and one spherical tumor (radius 4.