This large multicenter study of 37 magnetic resonance imaging scanners aimed at characterizing, for the first time, spatial profiles of inaccuracy (namely, Δ-profiles) in apparent diffusion coefficient (ADC) values with varying acquisition plan orientation and diffusion weighting gradient direction, using a statistical approach exploiting unsupervised clustering analysis. A diffusion-weighted imaging (DWI) protocol (b-value: 0-200-400-600-800-1000 s mm) with different combinations of acquisition plan orientation (axial/sagittal/coronal) and diffusion weighting gradient direction (anterior-posterior/left-right/feet-head) was acquired on a standard water phantom. For each acquisition setup, Δ-profiles along the 3 main orthogonal directions were characterized by fitting data with a second order polynomial function ().
View Article and Find Full Text PDFStrong-field quantum electrodynamics (SF QED) is a burgeoning research topic dealing with electromagnetic fields comparable to the Schwinger field (≈1.32×10^{18} V/m). While most past and proposed experiments rely on reaching this field in the rest frame of relativistic particles, the Schwinger limit could also be approached in the laboratory frame by focusing to its diffraction limit the light reflected by a plasma mirror irradiated by a multipetawatt laser.
View Article and Find Full Text PDFOur work investigated the radioprotection implications associated with the possession of a collection of uraniferous minerals. Considering different scenarios, we developed (and applied to an actual collection) specific formulas for radiation doses evaluation. We discussed the shielding necessary to reduce the gamma irradiation down to the required values.
View Article and Find Full Text PDFIntroduction: Both cone-beam computed tomography (CBCT) and surface-guided radiotherapy (SGRT) are used for breast patient positioning verification before treatment delivery. SGRT may reduce treatment time and imaging dose by potentially reduce the number of CBCT needed. The aim of this study was to compare the displacements resulting in positioning from the Image Guided Radiation Therapy (IGRT) 3D and SGRT methods and to design a clinical workflow for SGRT implementation in breast radiotherapy to establish an imaging strategy based on the data obtained.
View Article and Find Full Text PDFBackground: Despite substantial research, the mechanisms behind stress Tako-tsubo cardiomyopathy (TTC) remain rather elusive.
Objective: The purpose of this paper was to provide a detailed review of the mainstream factors underlying the pathophysiology of TTC, highlighting the novel contributions of molecular pathology and in-vivo molecular imaging.
Methods: A careful literature review selected all papers discussing TTC, specifically those providing novel insights from myocardial pathology and cardiac molecular imaging.
Radiat Prot Dosimetry
March 2022
The activity estimation of hand-size specimens of uraniferous minerals is not a trivial issue due to the manipulation difficulty caused by the emitted ionising radiation and the dependence of radiometric quantities from several parameters. Sample modelling requires approximations, leading to large uncertainty in the evaluation of the activity. In this work, a new procedure to evaluate uraniferous specimens activity, including a detailed description of measured parameters, the instrumentation and the mathematical formulation of the process, is presented.
View Article and Find Full Text PDFTriage is crucial for patient's management and estimation of the required intensive care unit (ICU) beds is fundamental for health systems during the COVID-19 pandemic. We assessed whether chest computed tomography (CT) of COVID-19 pneumonia has an incremental role in predicting patient's admission to ICU. We performed volumetric and texture analysis of the areas of the affected lung in CT of 115 outpatients with COVID-19 infection presenting to the emergency room with dyspnea and unresponsive hypoxyemia.
View Article and Find Full Text PDFPurpose: The purpose of this multicenter phantom study was to exploit an innovative approach, based on an extensive acquisition protocol and unsupervised clustering analysis, in order to assess any potential bias in apparent diffusion coefficient (ADC) estimation due to different scanner characteristics. Moreover, we aimed at assessing, for the first time, any effect of acquisition plan/phase encoding direction on ADC estimation.
Methods: Water phantom acquisitions were carried out on 39 scanners.
Purpose: To perform a multi-centre survey on the eye lens equivalent dose absorbed by primary interventionalist during catheterization procedures, using a personal dosimeter placed close to the eye lens.
Methods: 15 different cardiologists working in 3 different centers, for a total of 5 operating rooms were enrolled. All of them were provided with a single thermoluminescent dosimeter positioned on the inner side of the temples of eyeglasses.
Pre and post-operative exposure levels of medical staff and people from public in intra-operative Ru-106 ophthalmic brachytherapy are reported, together with attenuation properties of selected shielding materials. In particular radiation exposure of workers during plaque transportation and during medical assistance of implanted plaque patient was measured. Taking into account dose rates and considering standard assistance procedure of hospitalized patients, the exposure of medical staff and people of the public were evaluated for a given workload.
View Article and Find Full Text PDFPurpose: To propose an MRI quality assurance procedure that can be used for routine controls and multi-centre comparison of different MR-scanners for quantitative diffusion-weighted imaging (DWI).
Materials And Methods: 44 MR-scanners with different field strengths (1 T, 1.5 T and 3 T) were included in the study.
Purpose: The aim of this study was to propose and validate across various clinical scanner systems a straightforward multiparametric quality assurance procedure for proton magnetic resonance spectroscopy (MRS).
Methods: Eighteen clinical 1.5 T and 3 T scanner systems for MRS, from 16 centres and 3 different manufacturers, were enrolled in the study.
Near-critical plasmas irradiated at ultra-high laser intensities (I > 10W/cm) allow to improve the performances of laser-driven particle and radiation sources and to explore scenarios of great astrophysical interest. Near-critical plasmas with controlled properties can be obtained with nanostructured low-density materials. By means of 3D Particle-In-Cell simulations, we investigate how realistic nanostructures influence the interaction of an ultra-intense laser with a plasma having a near-critical average electron density.
View Article and Find Full Text PDFPurpose: This study aimed to test the sensitivity of a transmission detector for online dose monitoring of intensity-modulated radiation therapy (IMRT) for detecting small delivery errors. Furthermore, the correlation of changes in detector output induced by small delivery errors with other metrics commonly employed to quantify the deviations between calculated and delivered dose distributions was investigated.
Methods: Transmission detector measurements were performed at three institutions.
Purpose: To propose a magnetic resonance imaging (MRI) quality assurance procedure that can be used for multicenter comparison of different MR scanners for quantitative diffusion-weighted imaging (DWI).
Materials And Methods: Twenty-six centers (35 MR scanners with field strengths: 1T, 1.5T, and 3T) were enrolled in the study.