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Metzner M, Zhevachevska D, Schlechter A, Kehrein F, Schlecker J, Murillo C, Brons S, Jäkel O, Martišíková M, Gehrke T. Energy painting: helium-beam radiography with thin detectors and multiple beam energies. Phys Med Biol 2024; 69:055002. [PMID: 38295403 DOI: 10.1088/1361-6560/ad247e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/31/2024] [Indexed: 02/02/2024]
Abstract
Objective.Compact ion imaging systems based on thin detectors are a promising prospect for the clinical environment since they are easily integrated into the clinical workflow. Their measurement principle is based on energy deposition instead of the conventionally measured residual energy or range. Therefore, thin detectors are limited in the water-equivalent thickness range they can image with high precision. This article presents ourenergy paintingmethod, which has been developed to render high precision imaging with thin detectors feasible even for objects with larger, clinically relevant water-equivalent thickness (WET) ranges.Approach.A detection system exclusively based on pixelated silicon Timepix detectors was used at the Heidelberg ion-beam therapy center to track single helium ions and measure their energy deposition behind the imaged object. Calibration curves were established for five initial beam energies to relate the measured energy deposition to WET. They were evaluated regarding their accuracy, precision and temporal stability. Furthermore, a 60 mm × 12 mm region of a wedge phantom was imaged quantitatively exploiting the calibrated energies and five different mono-energetic images. These mono-energetic images were combined in a pixel-by-pixel manner by averaging the WET-data weighted according to their single-ion WET precision (SIWP) and the number of contributing ions.Main result.A quantitative helium-beam radiograph of the wedge phantom with an average SIWP of 1.82(5) % over the entire WET interval from 150 mm to 220 mm was obtained. Compared to the previously used methodology, the SIWP improved by a factor of 2.49 ± 0.16. The relative stopping power value of the wedge derived from the energy-painted image matches the result from range pullback measurements with a relative deviation of only 0.4 %.Significance.The proposed method overcomes the insufficient precision for wide WET ranges when employing detection systems with thin detectors. Applying this method is an important prerequisite for imaging of patients. Hence, it advances detection systems based on energy deposition measurements towards clinical implementation.
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Affiliation(s)
- Margareta Metzner
- Heidelberg Institute for Radiation Oncology (HIRO) and National Center for Research in Radiation Oncology (NCRO), Heidelberg, Germany
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiation Oncology, Germany
- Department of Physics and Astronomy, Heidelberg University, Heidelberg, Germany
| | - Daria Zhevachevska
- Heidelberg Institute for Radiation Oncology (HIRO) and National Center for Research in Radiation Oncology (NCRO), Heidelberg, Germany
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiation Oncology, Germany
- Heidelberg University, Medical Faculty Mannheim, Heidelberg, Germany
| | - Annika Schlechter
- Heidelberg Institute for Radiation Oncology (HIRO) and National Center for Research in Radiation Oncology (NCRO), Heidelberg, Germany
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiation Oncology, Germany
- Department of Physics and Astronomy, Heidelberg University, Heidelberg, Germany
| | - Florian Kehrein
- Heidelberg Institute for Radiation Oncology (HIRO) and National Center for Research in Radiation Oncology (NCRO), Heidelberg, Germany
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiation Oncology, Germany
- Department of Physics and Astronomy, Heidelberg University, Heidelberg, Germany
| | - Julian Schlecker
- Heidelberg Institute for Radiation Oncology (HIRO) and National Center for Research in Radiation Oncology (NCRO), Heidelberg, Germany
- German Cancer Research Center (DKFZ) Heidelberg, Division of Radiooncology/Radiobiology, Germany
| | - Carlos Murillo
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiology, Germany
| | - Stephan Brons
- Heidelberg Ion-Beam Therapy Center (HIT), Radiation Oncology - Heidelberg University Hospital, Heidelberg, Germany
| | - Oliver Jäkel
- Heidelberg Institute for Radiation Oncology (HIRO) and National Center for Research in Radiation Oncology (NCRO), Heidelberg, Germany
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiation Oncology, Germany
- Heidelberg Ion-Beam Therapy Center (HIT), Radiation Oncology - Heidelberg University Hospital, Heidelberg, Germany
| | - Mária Martišíková
- Heidelberg Institute for Radiation Oncology (HIRO) and National Center for Research in Radiation Oncology (NCRO), Heidelberg, Germany
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiation Oncology, Germany
| | - Tim Gehrke
- Heidelberg Institute for Radiation Oncology (HIRO) and National Center for Research in Radiation Oncology (NCRO), Heidelberg, Germany
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiation Oncology, Germany
- Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
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Volz L, Graeff C, Durante M, Collins-Fekete CA. Focus stacking single-event particle radiography for high spatial resolution images and 3D feature localization. Phys Med Biol 2024; 69:024001. [PMID: 38056016 PMCID: PMC10777170 DOI: 10.1088/1361-6560/ad131a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 11/22/2023] [Accepted: 12/06/2023] [Indexed: 12/08/2023]
Abstract
Objective.We demonstrate a novel focus stacking technique to improve spatial resolution of single-event particle radiography (pRad), and exploit its potential for 3D feature detection.Approach.Focus stacking, used typically in optical photography and microscopy, is a technique to combine multiple images with different focal depths into a single super-resolution image. Each pixel in the final image is chosen from the image with the largest gradient at that pixel's position. pRad data can be reconstructed at different depths in the patient based on an estimate of each particle's trajectory (called distance-driven binning; DDB). For a given feature, there is a depth of reconstruction for which the spatial resolution of DDB is maximal. Focus stacking can hence be applied to a series of DDB images reconstructed from a single pRad acquisition for different depths, yielding both a high-resolution projection and information on the features' radiological depth at the same time. We demonstrate this technique with Geant4 simulated pRads of a water phantom (20 cm thick) with five bone cube inserts at different depths (1 × 1 × 1 cm3) and a lung cancer patient.Main results.For proton radiography of the cube phantom, focus stacking achieved a median resolution improvement of 136% compared to a state-of-the-art maximum likelihood pRad reconstruction algorithm and a median of 28% compared to DDB where the reconstruction depth was the center of each cube. For the lung patient, resolution was visually improved, without loss in accuracy. The focus stacking method also enabled to estimate the depth of the cubes within few millimeters accuracy, except for one shallow cube, where the depth was underestimated by 2.5 cm.Significance.Focus stacking utilizes the inherent 3D information encoded in pRad by the particle's scattering, overcoming current spatial resolution limits. It further opens possibilities for 3D feature localization. Therefore, focus stacking holds great potential for future pRad applications.
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Affiliation(s)
- Lennart Volz
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
| | - Christian Graeff
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
- Department of Electrical Engineering and Information Technology, Technical University of Darmstadt, Darmstadt, Germany
| | - Marco Durante
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
- Department of Condensed Matter Physics, Technical University of Darmstadt, Darmstadt, Germany
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Dorst AC, Dissanayake REA, Schauermann D, Knies S, Wodtke AM, Killelea DR, Schäfer T. Hyperthermal velocity distributions of recombinatively-desorbing oxygen from Ag(111). Front Chem 2023; 11:1248456. [PMID: 37601906 PMCID: PMC10433164 DOI: 10.3389/fchem.2023.1248456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 07/20/2023] [Indexed: 08/22/2023] Open
Abstract
This study presents velocity-resolved desorption experiments of recombinatively-desorbing oxygen from Ag (111). We combine molecular beam techniques, ion imaging, and temperature-programmed desorption to obtain translational energy distributions of desorbing O2. Molecular beams of NO2 are used to prepare a p (4 × 4)-O adlayer on the silver crystal. The translational energy distributions of O2 are shifted towards hyperthermal energies indicating desorption from an intermediate activated molecular chemisorption state.
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Affiliation(s)
- Arved C. Dorst
- Institute of Physical Chemistry, University of Göttingen, Göttingen, Germany
- Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Rasika E. A. Dissanayake
- Institute of Physical Chemistry, University of Göttingen, Göttingen, Germany
- Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Daniel Schauermann
- Institute of Physical Chemistry, University of Göttingen, Göttingen, Germany
| | - Sofie Knies
- Faculty of Biology, Chemistry and Geosciences and Bavarian Center for Battery Technology, Bayreuth, Germany
| | - Alec M. Wodtke
- Institute of Physical Chemistry, University of Göttingen, Göttingen, Germany
- Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Daniel R. Killelea
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, United States
| | - Tim Schäfer
- Institute of Physical Chemistry, University of Göttingen, Göttingen, Germany
- Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
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Fogazzi E, Trevisan D, Farace P, Righetto R, Rit S, Scaringella M, Bruzzi M, Tommasino F, Civinini C. Characterization of the INFN proton CT scanner for cross-calibration of x-ray CT. Phys Med Biol 2023. [PMID: 37201529 DOI: 10.1088/1361-6560/acd6d3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
OBJECTIVE The goal of this study was to assess the imaging performances of the pCT system developed in the framework of INFN-funded (Italian National Institute of Nuclear Physics) research projects. The spatial resolution, noise power spectrum and RSP accuracy has been investigated, as a preliminary step to implement a new cross-calibration method for x-ray CT (xCT). 
Approach: The INFN pCT apparatus, made of four planes of silicon micro-strip detectors and a YAG:Ce scintillating calorimeter, reconstructs 3D RSP maps by a filtered-back projection algorithm. The imaging performances (i.e. spatial resolution, noise power spectrum and RSP accuracy) of the pCT system were assessed on a custom-made phantom, made of plastic materials with different densities ([0.66, 2.18] g/cm3). For comparison, the same phantom was acquired with a clinical xCT system.
Main results: The spatial resolution analysis revealed the non-linearity of the imaging system, showing different imaging responses in air or water phantom background. Applying the Hann filter in the pCT reconstruction, it was possible to investigate the imaging potential of the system. Matching the spatial resolution value of the xCT (0.54 lp/mm) and acquiring both with the same dose level (11.6 mGy), the pCT appeared to be less noisy than xCT, with an RSP standard deviation of 0.0063. Concerning the RSP accuracy, the measured Mean Absolute Percentage Errors were (0.23+-0.09)% in air and (0.21+-0.07)% in water.
Significance: The obtained performances confirm that the INFN pCT system provides a very accurate RSP estimation, appearing to be a feasible clinical tool for verification and correction of xCT calibration in proton treatment planning.
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Affiliation(s)
- Elena Fogazzi
- Dipartimento di Fisica, Università degli Studi di Trento, Via Sommarive, 14, Povo (TN), 38122, ITALY
| | - Diego Trevisan
- Medical Physics Unit, , Hospital of Trento, Azienda Provinciale per i Servizi Sanitari (APSS), via Paolo Orsi, 1, Trento, 38122, ITALY
| | - Paolo Farace
- Medical Physics Unit, Hospital of Trento, Azienda Provinciale per i Servizi Sanitari (APSS), via Paolo Orsi, 1, Trento, 38122, ITALY
| | - Roberto Righetto
- Medical Physics Unit, Hospital of Trento, Azienda Provinciale per i Servizi Sanitari (APSS), via Paolo Orsi, 1, Trento, Trento, 38122, ITALY
| | - Simon Rit
- Université de Lyon, CREATIS ; CNRS UMR5220 ; Inserm U1206 ; INSA-Lyon ; Université Lyon 1, CREATIS, Centre Léon Bérard, Lyon, 69373, FRANCE
| | - Monica Scaringella
- Istituto Nazionale di Fisica Nucleare Sezione di Firenze, Via G. Sansone 1, Sesto Fiorentino, 50019, ITALY
| | - Mara Bruzzi
- Dipartimento di Fisica e Astronomia, Universita di Firenze, Via G. Sansone, 1, Sesto Fiorentino, 50019, ITALY
| | - Francesco Tommasino
- Physics, University of Trento, via Sommarive, 14, Trento, Trentino-Alto Adige, 38122, ITALY
| | - Carlo Civinini
- Istituto Nazionale di Fisica Nucleare Sezione di Firenze, Via G. Sansone, 1, Sesto Fiorentino, 50019, ITALY
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Fullarton R, Volz L, Dikaios N, Schulte R, Royle G, Evans PM, Seco J, Collins‐Fekete C. A likelihood-based particle imaging filter using prior information. Med Phys 2023; 50:2336-2353. [PMID: 36727634 PMCID: PMC10947404 DOI: 10.1002/mp.16258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 01/13/2023] [Accepted: 01/13/2023] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Particle imaging can increase precision in proton and ion therapy. Interactions with nuclei in the imaged object increase image noise and reduce image quality, especially for multinucleon ions that can fragment, such as helium. PURPOSE This work proposes a particle imaging filter, referred to as the Prior Filter, based on using prior information in the form of an estimated relative stopping power (RSP) map and the principles of electromagnetic interaction, to identify particles that have undergone nuclear interaction. The particles identified as having undergone nuclear interactions are then excluded from the image reconstruction, reducing the image noise. METHODS The Prior Filter uses Fermi-Eyges scattering and Tschalär straggling theories to determine the likelihood that a particle only interacts electromagnetically. A threshold is then set to reject those particles with a low likelihood. The filter was evaluated and compared with a filter that estimates this likelihood based on the measured distribution of energy and scattering angle within pixels, commonly implemented as the 3σ filter. Reconstructed radiographs from simulated data of a 20-cm water cylinder and an anthropomorphic chest phantom were generated with both protons and helium ions to assess the effect of the filters on noise reduction. The simulation also allowed assessment of secondary particle removal through the particle histories. Experimental data were acquired of the Catphan CTP 404 Sensitometry phantom using the U.S. proton CT (pCT) collaboration prototype scanner. The proton and helium images were filtered with both the prior filtering method and a state-of-the-art method including an implementation of the 3σ filter. For both cases, a dE-E telescope filter, designed for this type of detector, was also applied. RESULTS The proton radiographs showed a small reduction in noise (1 mm of water-equivalent thickness [WET]) but a larger reduction in helium radiographs (up to 5-6 mm of WET) due to better secondary filtering. The proton and helium CT images reflected this, with similar noise at the center of the phantom (0.02 RSP) for the proton images and an RSP noise of 0.03 for the proposed filter and 0.06 for the 3σ filter in the helium images. Images reconstructed from data with a dose reduction, up to a factor of 9, maintained a lower noise level using the Prior Filter over the state-of-the-art filtering method. CONCLUSIONS The proposed filter results in images with equal or reduced noise compared to those that have undergone a filtering method typical of current particle imaging studies. This work also demonstrates that the proposed filter maintains better performance against the state of the art with up to a nine-fold dose reduction.
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Affiliation(s)
- Ryan Fullarton
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Lennart Volz
- Department of Biomedical Physics in Radiation OncologyDeutsches Krebsforschungszentrum (DKFZ)HeidelbergGermany
- Department of Physics and AstronomyHeidelberg UniversityHeidelbergGermany
- GSI Helmholtz Centre for Heavy Ion Research GmbHDarmstadtGermany
| | - Nikolaos Dikaios
- Centre for Vision Speech and Signal ProcessingUniversity of SurreyGuildfordUK
- Mathematics Research CenterAcademy of AthensAthensGreece
| | - Reinhard Schulte
- Department of Basic SciencesDivision of Biomedical Engineering SciencesLoma Linda UniversityLoma LindaCaliforniaUSA
| | - Gary Royle
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Philip M. Evans
- Centre for Vision Speech and Signal ProcessingUniversity of SurreyGuildfordUK
- Chemical, Medical and Environmental ScienceNational Physical LaboratoryTeddingtonUK
| | - Joao Seco
- Department of Biomedical Physics in Radiation OncologyDeutsches Krebsforschungszentrum (DKFZ)HeidelbergGermany
- Department of Physics and AstronomyHeidelberg UniversityHeidelbergGermany
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Knobloch C, Metzner M, Kehrein F, Schömers C, Scheloske S, Brons S, Hermann R, Peters A, Jäkel O, Martišíková M, Gehrke T. Experimental helium-beam radiography with a high-energy beam: Water-equivalent thickness calibration and first image-quality results. Med Phys 2022; 49:5347-5362. [PMID: 35670033 DOI: 10.1002/mp.15795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 05/05/2022] [Accepted: 05/18/2022] [Indexed: 11/06/2022] Open
Abstract
PURPOSE A clinical implementation of ion-beam radiography (iRad) is envisaged to provide a method for on-couch verification of ion-beam treatment plans. The aim of this work is to introduce and evaluate a method for quantitative water-equivalent thickness (WET) measurements for a specific helium-ion imaging system for WETs that are relevant for imaging thicker body parts in the future. METHODS Helium-beam radiographs (αRads) are measured at the Heidelberg Ion-beam Therapy Center (HIT) with an initial beam energy of 239.5 MeV/ u. An imaging system based on three pairs of thin silicon pixel detectors is used for ion path reconstruction and measuring the energy deposition (dE) of each particle behind the object to be imaged. The dE behind homogeneous plastic blocks is related to their well-known WETs between 280.6mm and 312.6 mm with a calibration curve that is created by fitting the measured data points. The quality of the quantitative WET measurements is determined by the uncertainty of the measured WET of a single ion (single-ion WET precision) and the deviation of a measured WET value to the well-known WET (WET accuracy). Subsequently, the fitted calibration curve is applied to an energy deposition radiograph of a phantom with a complex geometry. The spatial resolution (modulation transfer function at 10% (MTF10% )) and WET accuracy (mean absolute percentage difference (MAPD)) of the WET map, are determined. RESULTS In the optimal imaging WET-range from ∼ 280 mm to 300 mm, the fitted calibration curve reached a mean single-ion WET precision of 1.55 ± 0.00%. Applying the calibration to an ion radiograph (iRad) of a more complex WET distribution, the spatial resolution was determined to be MTF10% = 0.49 ± 0.03 lp/mm and the WET accuracy was assessed as MAPD to 0.21%. CONCLUSIONS Using a beam energy of 239.5MeV/ u and the proposed calibration procedure, quantitative αRads of WETs between ∼ 280mm to 300 mm can be measured and show high potential for clinical use. The proposed approach with the resulting image qualities encourages further investigation towards the clinical application of helium-beam radiography. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- C Knobloch
- German Cancer Research Center (DKFZ), Department of Medical Physics in Radiation Oncology, Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany.,Heidelberg University, Department of Physics and Astronomy, Heidelberg, Germany
| | - M Metzner
- German Cancer Research Center (DKFZ), Department of Medical Physics in Radiation Oncology, Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany.,Heidelberg University, Department of Physics and Astronomy, Heidelberg, Germany
| | - F Kehrein
- German Cancer Research Center (DKFZ), Department of Medical Physics in Radiation Oncology, Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany.,Heidelberg University, Department of Physics and Astronomy, Heidelberg, Germany
| | - C Schömers
- Heidelberg Ion-Beam Therapy Centre (HIT), Department of Radiation Oncology Heidelberg University Hospital, Heidelberg, Germany
| | - S Scheloske
- Heidelberg Ion-Beam Therapy Centre (HIT), Department of Radiation Oncology Heidelberg University Hospital, Heidelberg, Germany
| | - S Brons
- Heidelberg Ion-Beam Therapy Centre (HIT), Department of Radiation Oncology Heidelberg University Hospital, Heidelberg, Germany
| | - R Hermann
- Heidelberg Ion-Beam Therapy Centre (HIT), Department of Radiation Oncology Heidelberg University Hospital, Heidelberg, Germany.,Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg, Germany.,Goethe University Frankfurt, Institute of Applied Physics, Frankfurt, Germany
| | - A Peters
- Heidelberg Ion-Beam Therapy Centre (HIT), Department of Radiation Oncology Heidelberg University Hospital, Heidelberg, Germany
| | - O Jäkel
- German Cancer Research Center (DKFZ), Department of Medical Physics in Radiation Oncology, Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany.,Heidelberg Ion-Beam Therapy Centre (HIT), Department of Radiation Oncology Heidelberg University Hospital, Heidelberg, Germany
| | - M Martišíková
- German Cancer Research Center (DKFZ), Department of Medical Physics in Radiation Oncology, Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - T Gehrke
- German Cancer Research Center (DKFZ), Department of Medical Physics in Radiation Oncology, Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany.,Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg, Germany
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Volz L, Piersimoni P, Bashkirov VA, Brons S, Collins-Fekete CA, Johnson RP, Schulte RW, Seco J. The impact of secondary fragments on the image quality of helium ion imaging. Phys Med Biol 2018; 63:195016. [PMID: 30183679 PMCID: PMC6380898 DOI: 10.1088/1361-6560/aadf25] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Single-event ion imaging enables the direct reconstruction of the relative stopping power (RSP) information required for ion-beam therapy. Helium ions were recently hypothesized to be the optimal species for such technique. The purpose of this work is to investigate the effect of secondary fragments on the image quality of helium CT (HeCT) and to assess the performance of a prototype proton CT (pCT) scanner when operated with helium beams in Monte Carlo simulations and experiment. Experiments were conducted installing the U.S. pCT consortium prototype scanner at the Heidelberg Ion-Beam Therapy Center (HIT). Simulations were performed with the scanner using the TOPAS toolkit. HeCT images were reconstructed for a cylindrical water phantom, the CTP404 (sensitometry), and the CTP528 (line-pair) [Formula: see text] ® modules. To identify and remove individual events caused by fragmentation, the multistage energy detector of the scanner was adapted to function as a [Formula: see text] telescope. The use of the developed filter eliminated the otherwise arising ring artifacts in the HeCT reconstructed images. For the HeCT reconstructed images of a water phantom, the maximum RSP error was improved by almost a factor 8 with respect to unfiltered images in the simulation and a factor 10 in the experiment. Similarly, for the CTP404 module, the mean RSP accuracy improved by a factor 6 in both the simulation and the experiment when the filter was applied (mean relative error 0.40% in simulation, 0.45% in experiment). In the evaluation of the spatial resolution through the CTP528 module, the main effect of the filter was noise reduction. For both simulated and experimental images the spatial resolution was ∼4 lp cm-1. In conclusion, the novel filter developed for secondary fragments proved to be effective in improving the visual quality and RSP accuracy of the reconstructed images. With the filter, the pCT scanner is capable of accurate HeCT imaging.
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Affiliation(s)
- Lennart Volz
- German Cancer Research Center (DKFZ) Heidelberg, Baden-Württemberg, Germany. Department of Physics and Astronomy, Heidelberg University, Heidelberg, Baden-Württemberg, Germany. These authors contributed equally to this work
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Luongo F, Pietropaolo G, Gautier M, Dhennin-Duthille I, Ouadid-Ahidouch H, Wolf FI, Trapani V. TRPM6 is Essential for Magnesium Uptake and Epithelial Cell Function in the Colon. Nutrients 2018; 10:E784. [PMID: 29912157 DOI: 10.3390/nu10060784] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 06/12/2018] [Accepted: 06/13/2018] [Indexed: 11/24/2022] Open
Abstract
Intestinal magnesium (Mg) uptake is essential for systemic Mg homeostasis. Colon cells express the two highly homologous transient receptor potential melastatin type (TRPM) 6 and 7 Mg2+ channels, but their precise function and the consequences of their mutual interaction are not clear. To explore the functional role of TRPM6 and TRPM7 in the colon, we used human colon cell lines that innately express both channels and analyzed the functional consequences of genetic knocking-down, by RNA interference, or pharmacological inhibition, by NS8593, of either channel. TRPM7 silencing caused an increase in Mg2+ influx, and correspondingly enhanced cell proliferation and migration, while downregulation of TRPM6 did not affect significantly either Mg2+ influx or cell proliferation. Exposure to the specific TRPM6/7 inhibitor NS8593 reduced Mg2+ influx, and consequently cell proliferation and migration, but Mg supplementation rescued the inhibition. We propose a model whereby in colon cells the functional Mg2+ channel at the plasma membrane may consist of both TRPM7 homomers and TRPM6/7 heteromers. A different expression ratio between the two proteins may result in different functional properties. Altogether, our findings confirm that TRPM6 cannot be replaced by TRPM7, and that TRPM6/7 complexes and TRPM6/7-mediated Mg2+ influx are indispensable in human epithelial colon cells.
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Suhard D, Tessier C, Manens L, Rebière F, Tack K, Agarande M, Guéguen Y. Intracellular uranium distribution: Comparison of cryogenic fixation versus chemical fixation methods for SIMS analysis. Microsc Res Tech 2018; 81:855-864. [PMID: 29737608 PMCID: PMC6221105 DOI: 10.1002/jemt.23047] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 01/30/2018] [Accepted: 04/17/2018] [Indexed: 12/30/2022]
Abstract
Localization of uranium within cells is mandatory for the comprehension of its cellular mechanism of toxicity. Secondary Ion Mass Spectrometry (SIMS) has recently shown its interest to detect and localize uranium at very low levels within the cells. This technique requires a specific sample preparation similar to the one used for Transmission Electronic Microscopy, achieved by implementing different chemical treatments to preserve as much as possible the living configuration uranium distribution into the observed sample. This study aims to compare the bioaccumulation sites of uranium within liver or kidney cells after chemical fixation and cryomethods preparations of the samples: SIMS analysis of theses samples show the localization of uranium soluble forms in the cell cytoplasm and nucleus with a more homogenous distribution when using cryopreparation probably due to the diffusible portion of uranium inside the cytoplasm.
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Affiliation(s)
- D Suhard
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SESANE, Fontenay-aux-Roses, France
| | - C Tessier
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SESANE, Fontenay-aux-Roses, France
| | - L Manens
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SESANE, Fontenay-aux-Roses, France
| | - F Rebière
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SESANE, Fontenay-aux-Roses, France
| | - K Tack
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SESANE, Fontenay-aux-Roses, France
| | - M Agarande
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SAME, Le Vésinet, France
| | - Y Guéguen
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SESANE, Fontenay-aux-Roses, France
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10
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Abstract
We summarize how gas-phase ultrafast charged-particle spectroscopy has been used to provide an understanding of the photophysics of DNA building blocks. We focus on adenine and discuss how, following UV excitation, specific interactions determine the fates of its excited states. The dynamics can be probed using a systematic bottom-up approach that provides control over these interactions and that allows ever-larger complexes to be studied. Starting from a chromophore in adenine, the excited state decay mechanisms of adenine and chemically substituted or clustered adenine are considered and then extended to adenosine mono-, di-, and trinucleotides. We show that the gas-phase approach can offer exquisite insight into the dynamics observed in aqueous solution, but we also highlight stark differences. An outlook is provided that discusses some of the most promising developments in this bottom-up approach.
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Affiliation(s)
- Vasilios G Stavros
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom;
| | - Jan R R Verlet
- Department of Chemistry, University of Durham, Durham, DH1 3LE, United Kingdom;
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11
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Mizuse K, Kitano K, Hasegawa H, Ohshima Y. Quantum unidirectional rotation directly imaged with molecules. Sci Adv 2015; 1:e1400185. [PMID: 26601205 PMCID: PMC4646765 DOI: 10.1126/sciadv.1400185] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 05/19/2015] [Indexed: 06/05/2023]
Abstract
A gas-phase molecular ensemble coherently excited to have an oriented rotational angular momentum has recently emerged as an appropriate microscopic system to illustrate quantum mechanical behavior directly linked to classical rotational motion, which has a definite direction. To realize an intuitive visualization of such a unidirectional molecular rotation, we report high-resolution direct imaging of direction-controlled rotational wave packets in nitrogen molecules. The rotational direction was regulated by a pair of time-delayed, polarization-skewed laser pulses, introducing the dynamic chirality to the system. The subsequent spatiotemporal propagation was tracked by a newly developed Coulomb explosion imaging setup. From the observed molecular movie, time-dependent detailed nodal structures, instantaneous alignment, angular dispersion, and fractional revivals of the wave packet are fully characterized while the ensemble keeps rotating in one direction. The present approach, providing an accurate view on unidirectional rotation in quantum regime, will guide more sophisticated molecular manipulations by utilizing its capability in capturing highly structured spatiotemporal evolution of molecular wave packets.
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Affiliation(s)
- Kenta Mizuse
- Institute for Molecular Science, National Institutes of Natural Sciences and SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan
| | - Kenta Kitano
- Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 252-5258, Japan
| | - Hirokazu Hasegawa
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan
| | - Yasuhiro Ohshima
- Institute for Molecular Science, National Institutes of Natural Sciences and SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8550, Japan
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12
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Pei L, Carrascosa E, Yang N, Falcinelli S, Farrar JM. Velocity Map Imaging Study of Charge-Transfer and Proton-Transfer Reactions of CH3 Radicals with H3(.). J Phys Chem Lett 2015; 6:1684-1689. [PMID: 26263334 DOI: 10.1021/acs.jpclett.5b00517] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The velocity map imaging method has been applied to crossed beam studies of charge transfer and proton transfer between methyl (CH3) radicals formed by pyrolysis and H3(+) cations over the collision energy range from 1.2 to 3.4 eV. Vibrational excitation in the H3(+) reactants plays an important role both in promoting endoergic charge transfer and in supplying energy to the products of the proton-transfer reaction. Excited H3(+) reactants with vibrational energy in excess of the barrier lead to energy-resonant charge transfer via long-range collisions. A small fraction of collisions that take place at low impact parameters appear to form charge-transfer products with higher levels of internal excitation. The proton-transfer reaction exhibits direct, stripping-like dynamics. Consistent with the kinematics of proton transfer, incremental kinetic energy supplied to the reactants is strongly directed into product relative kinetic energy, as predicted by the concept of "induced repulsive energy release".
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Affiliation(s)
- Linsen Pei
- †Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Eduardo Carrascosa
- ‡Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Nan Yang
- †Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Stefano Falcinelli
- §Dipartimento di Ingegneria Civile ed Ambientale, Università degli Studi di Perugia, 06125 Perugia, Italy
| | - James M Farrar
- †Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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Goldberg NT, Zhang J, Koszinowski K, Bouakline F, Althorpe SC, Zare RN. Vibrationally inelastic H + D2 collisions are forward-scattered. Proc Natl Acad Sci U S A 2008; 105:18194-9. [PMID: 19015513 PMCID: PMC2587579 DOI: 10.1073/pnas.0807942105] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Indexed: 11/18/2022] Open
Abstract
We have measured differential cross sections (DCSs) for the vibrationally inelastic scattering process H + o-D(2)(v = 0, j = 0,2) --> H + o-D(2)(v' = 1-4, j' even). Several different collision energies and nearly the entire range of populated product quantum states are studied. The products are dominantly forward-scattered in all cases. This behavior is the opposite of what is predicted by the conventional textbook mechanism, in which collisions at small impact parameters compress the bond and cause the products to recoil in the backward direction. Recent quasiclassical trajectory (QCT) calculations examining only the o-D(2)(v' = 3, j') products suggest that vibrationally inelastic scattering is the result of a frustrated reaction in which the D-D bond is stretched, but not broken, during the collision. These QCT calculations provide a qualitative explanation for the observed forward-scattering, but they do not agree with experiments at the lowest values of j'. The present work shows that quantum mechanical calculations agree closely with experiments and expands upon previous results to show that forward-scattering is universally observed in vibrationally inelastic H + D(2) collisions over a broad range of conditions.
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Affiliation(s)
- Noah T. Goldberg
- Department of Chemistry, Stanford University, Stanford, CA 94305-5080; and
| | - Jianyang Zhang
- Department of Chemistry, Stanford University, Stanford, CA 94305-5080; and
| | - Konrad Koszinowski
- Department of Chemistry, Stanford University, Stanford, CA 94305-5080; and
| | - Foudhil Bouakline
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Stuart C. Althorpe
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Richard N. Zare
- Department of Chemistry, Stanford University, Stanford, CA 94305-5080; and
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