scholarly journals Joint inversion of gravity with cosmic ray muon data at a well-characterized site for shallow subsurface density prediction

2019 ◽  
Vol 217 (3) ◽  
pp. 1988-2002 ◽  
Author(s):  
Katherine Cosburn ◽  
Mousumi Roy ◽  
Elena Guardincerri ◽  
Charlotte Rowe
Keyword(s):  
Joint Inversion ◽  
Spatial Scales ◽  
Cosmic Ray ◽  
Target Volume ◽  
Density Structure ◽  
Shallow Subsurface ◽  
Density Prediction ◽  
Muon Tomography ◽  
Gravity Measurements ◽  
Set Up

SUMMARYEstimating subsurface density is important for imaging various geologic structures such as volcanic edifices, reservoirs and aquifers. Muon tomography has recently been used to complement traditional gravity measurements as a powerful method for probing shallow subsurface density structure beneath volcanoes. Gravity and muon data have markedly different spatial sensitivities and, as a result, the combination is useful for imaging structures on spatial scales that are larger than the area encompassed by crossing muon trajectories. Here we explore and test a joint inversion of gravity and muon data in a study area where there is an independently characterized target anomaly: a regionally extensive, high-density layer beneath Los Alamos, New Mexico, USA. We resolve the nearly flat-lying structure using a unique experimental set-up wherein surface and subsurface gravity and muon measurements are obtained above and below the target volume. Our results show that with minimal geologic (prior) constraints, the joint inversion correctly recovers salient features of the expected density structure. The results of our study illustrate the potential of combining surface and subsurface (e.g. borehole) gravity and muon measurements to invert for shallow geologic structures.

scholarly journals Improvement of density models of geological structures by fusion of gravity data and cosmic muon radiographies

2015 ◽  
Vol 5 (1) ◽  
pp. 83-116 ◽  
Author(s):  
K. Jourde ◽  
D. Gibert ◽  
J. Marteau
Keyword(s):  
Gravity Data ◽  
Field Measurements ◽  
Small Scale ◽  
Density Structure ◽  
Spatial Filters ◽  
Muon Tomography ◽  
Mathematical Expressions ◽  
Integration Formulas ◽  
Muon Radiography ◽  
Gravity Measurements

Abstract. This paper examines how the resolution of small-scale geological density models is improved through the fusion of information provided by gravity measurements and density muon radiographies. Muon radiography aims at determining the density of geological bodies by measuring their screening effect on the natural flux of cosmic muons. Muon radiography essentially works like medical X-ray scan and integrates density information along elongated narrow conical volumes. Gravity measurements are linked to density by a 3-D integration encompassing the whole studied domain. We establish the mathematical expressions of these integration formulas – called acquisition kernels – and derive the resolving kernels that are spatial filters relating the true unknown density structure to the density distribution actually recovered from the available data. The resolving kernels approach allows to quantitatively describe the improvement of the resolution of the density models achieved by merging gravity data and muon radiographies. The method developed in this paper may be used to optimally design the geometry of the field measurements to perform in order to obtain a given spatial resolution pattern of the density model to construct. The resolving kernels derived in the joined muon/gravimetry case indicate that gravity data are almost useless to constrain the density structure in regions sampled by more than two muon tomography acquisitions. Interestingly the resolution in deeper regions not sampled by muon tomography is significantly improved by joining the two techniques. The method is illustrated with examples for La Soufrière of Guadeloupe volcano.

scholarly journals Improvement of density models of geological structures by fusion of gravity data and cosmic muon radiographies

2015 ◽  
Vol 4 (2) ◽  
pp. 177-188 ◽  
Author(s):  
K. Jourde ◽  
D. Gibert ◽  
J. Marteau
Keyword(s):  
Gravity Data ◽  
Field Measurements ◽  
Small Scale ◽  
Density Structure ◽  
Spatial Filters ◽  
Muon Tomography ◽  
Mathematical Expressions ◽  
Muon Radiography ◽  
Gravity Measurements ◽  
Kernel Approach

Abstract. This paper examines how the resolution of small-scale geological density models is improved through the fusion of information provided by gravity measurements and density muon radiographies. Muon radiography aims at determining the density of geological bodies by measuring their screening effect on the natural flux of cosmic muons. Muon radiography essentially works like a medical X-ray scan and integrates density information along elongated narrow conical volumes. Gravity measurements are linked to density by a 3-D integration encompassing the whole studied domain. We establish the mathematical expressions of these integration formulas – called acquisition kernels – and derive the resolving kernels that are spatial filters relating the true unknown density structure to the density distribution actually recovered from the available data. The resolving kernel approach allows one to quantitatively describe the improvement of the resolution of the density models achieved by merging gravity data and muon radiographies. The method developed in this paper may be used to optimally design the geometry of the field measurements to be performed in order to obtain a given spatial resolution pattern of the density model to be constructed. The resolving kernels derived in the joined muon–gravimetry case indicate that gravity data are almost useless for constraining the density structure in regions sampled by more than two muon tomography acquisitions. Interestingly, the resolution in deeper regions not sampled by muon tomography is significantly improved by joining the two techniques. The method is illustrated with examples for the La Soufrière volcano of Guadeloupe.

FIRST IMAGES FROM THE CRIPT MUON TOMOGRAPHY SYSTEM

2014 ◽  
Vol 27 ◽  
pp. 1460129 ◽  
Author(s):  
J. ARMITAGE ◽  
J. BOTTE ◽  
K. BOUDJEMLINE ◽  
A. ERLANDSON ◽  
A. ROBICHAUD ◽  
...  
Keyword(s):  
Scintillation Counter ◽  
Cosmic Ray ◽  
Target Volume ◽  
Nuclear Materials ◽  
Tomography System ◽  
Intrinsic Resolution ◽  
Muon Tomography ◽  
Passive Tomography ◽  
Shipping Containers

The CRIPT Cosmic Ray Imaging and Passive Tomography system began data taking in September 2012. CRIPT is a “proof of principle” muon tomography system originally proposed to inspect cargo in shipping containers and to determine the presence of special nuclear materials. CRIPT uses 4 layers of 2 m x 2 m scintillation counter trackers, each layer measuring two coordinates. Two layers are used to track the incoming muon and two for the outgoing muon allowing the trajectories of the muon to be determined. The target volume is divided into voxels, and a Point of Closest Approach algorithm is used to determine the number of scattering events in each voxel, producing a 3D image. The system has been tested with various targets of depleted uranium, lead bricks, and tungsten rods. Data on the positional resolution has been taken and the intrinsic resolution is unfolded with the help of a simulation using GEANT4. The next steps include incorporation of data from the spectrometer section, which will assist in determining the muon's momentum and improve the determination of the density of the target.

scholarly journals Design and operation of a field telescope for cosmic ray geophysical tomography

2012 ◽  
Vol 1 (1) ◽  
pp. 33-42 ◽  
Author(s):  
N. Lesparre ◽  
J. Marteau ◽  
Y. Déclais ◽  
D. Gibert ◽  
B. Carlus ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Data Acquisition System ◽  
Muon Flux ◽  
Optical Fibres ◽  
Density Structure ◽  
Data Set ◽  
Photon Counter ◽  
Muon Tomography ◽  
Geophysical Tomography ◽  
Sky Conditions

Abstract. The cosmic ray muon tomography gives an access to the density structure of geological targets. In the present article we describe a muon telescope adapted to harsh environmental conditions. In particular the design optimizes the total weight and power consumption to ease the deployment and increase the autonomy of the detector. The muon telescopes consist of at least two scintillator detection matrices readout by photosensors via optical fibres. Two photosensor options have been studied. The baseline option foresees one multianode photomultiplier (MAPM) per matrix. A second option using one multipixel photon counter (MPPC) per bar is under development. The readout electronics and data acquisition system developed for both options are detailed. We present a first data set acquired in open-sky conditions compared with the muon flux detected across geological objects.

scholarly journals Design and operation of a field telescope for cosmic ray geophysical tomography

2011 ◽  
Vol 1 (1) ◽  
pp. 47-89
Author(s):  
N. Lesparre ◽  
J. Marteau ◽  
Y. Déclais ◽  
D. Gibert ◽  
B. Carlus ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Cosmic Ray ◽  
Data Acquisition System ◽  
Optical Fibres ◽  
Density Structure ◽  
Data Set ◽  
Photon Counter ◽  
Muon Tomography ◽  
Geophysical Tomography ◽  
Sky Conditions

Abstract. The cosmic ray muon tomography gives an access to the density structure of geological targets. In the present article we describe a muon telescope adapted to harsh environmental conditions. In particular the design optimizes the total weight and power consumption to ease the deployment and increase the autonomy of the detector. The muon telescopes consist of at least two scintillator detection matrices readout by photosensors via optical fibres. Two photosensor options have been studied. The baseline option foresees one multianode photomultiplier (MAPM) per matrix. A second option using one multipixel photon counter (MPPC) per bar is under development. The readout electronics and data acquisition system developed for both options are detailed. We present a first data set acquired in open-sky conditions.

Evaluation of set-up errors and estimation of set-up margin during external beam radiation therapy of prostate cancer using electronic portal imaging device (EPID)

2021 ◽  
pp. 1-8
Author(s):  
Daryoush Khoramian ◽  
Soroush Sistani ◽  
Bagher Farhood
Keyword(s):  
Prostate Cancer ◽  
Radiation Therapy ◽  
Target Volume ◽  
External Beam Radiation ◽  
Beam Radiation ◽  
Cancer Radiotherapy ◽  
Imaging Device ◽  
Portal Images ◽  
Set Up ◽  
Prostate Cancer Radiotherapy

Abstract Aim: In radiation therapy, accurate dose distribution in target volume requires accurate treatment setup. The set-up errors are unwanted and inherent in the treatment process. By achieving these errors, a set-up margin (SM) of clinical target volume (CTV) to planning target volume (PTV) can be determined. In the current study, systematic and random set-up errors that occurred during prostate cancer radiotherapy were measured by an electronic portal imaging device (EPID). The obtained values were used to propose the optimum CTV-to-PTV margin in prostate cancer radiotherapy. Materials and methods: A total of 21 patients with prostate cancer treated with external beam radiation therapy (EBRT) participated in this study. A total of 280 portal images were acquired during 12 months. Gross, population systematic (Σ) and random (σ) errors were obtained based on the portal images in Anterior–Posterior (AP), Medio-Lateral (ML) and Superior–Inferior (SI) directions. The SM of CTV to PTV were then calculated and compared by using the formulas presented by the International Commission on Radiation Units and Measurements (ICRU) 62, Stroom and Heijmen and Van Herk et al. Results: The findings showed that the population systematic errors during prostate cancer radiotherapy in AP, ML and SI directions were 1·40, 1·95 and 1·94 mm, respectively. The population random errors in AP, ML and SI directions were 2·09, 1·85 and 2·29 mm, respectively. The SM of CTV to PTV calculated in accordance with the formula of ICRU 62 in AP, ML and SI directions were 2·51, 2·68 and 3·00 mm, respectively. And according to Stroom and Heijmen, formula were 4·23, 5·19 and 5·48 mm, respectively. And Van Herk et al. formula were 4·96, 6·17 and 6·45 mm, respectively. Findings: The SM of CTV to PTV in all directions, based on the formulas of ICRU 62, Stroom and Heijmen and van Herk et al., were equal to 2·73, 4·98 and 5·86 mm, respectively; these values were obtained by averaging the margins in all directions.

scholarly journals An observational study of post-operative Volumetric Modulated Arc Radiotherapy (VMAT) of breast cancer by immobilizing patients on All-in-one (AIOTM) solution Breast and Lung Board without usingthermoplastic mask: Risk of collusion of gantry with couch exists if acquisition of Cone-beam Computed Tomography (CBCT)is attempted for set-up verification.

2020 ◽  
Author(s):  
Ramaiah Vinay Kumar
Keyword(s):  
Breast Cancer ◽  
Computed Tomography ◽  
Cancer Patients ◽  
Target Volume ◽  
Cone Beam ◽  
Breast Cancer Patients ◽  
Unilateral Breast Cancer ◽  
Planar Image ◽  
X Ray ◽  
Set Up

Abstract Background: Automatic Cone-beam computed tomography (CBCT) based image matching for set-up verification is recommended as compared to 2-D match for post-operative local / loco-regional radiotherapy of breast cancer patients by Volumetric Modulated Arc Therapy (VMAT) technique. However, in supine position, off-midline peripheral body Clinical Target Volume (CTV) of unilateral breast cancer patients immobilized on Breast and Lung board of All-in-One (AIO) positioning systemmay necessitate augmented movement of couch in ‘x’ and ‘z’ axis thereby raising the risk of collusion of x-ray sources / detectors system with couch. Methods and Materials: VMAT was planned by a pair of partial arc for whole target volume for seven consecutive post-operative breast cancer patients (five post-mastectomy and two post-breast conservation patients). Tattoo based set-up by shift of treatment table in x-, y- and z-axis as determined by Treatment Planning System followed by X-rays with planar image acquisition and online 2-D imaging matching was performed for set-up verification. In-room 360°rotation of x-ray source and detector system of linear accelerator (linac) was performed before x-ray planar image acquisition. Results: Completion of 360°rotation in-room of x-ray source and detector system of linacaround the machine iso-centre was not possible in six out of seven patients due to possibility of collusion of gantry with contralateral side of the couch. Conclusion: Performing CBCT for generating 3D images for computed tomography (CT) reconstruction may not be practical for patient set-up verification of post-operative radiotherapy of unilateral breast cancer patients positioned supine on breast and lung board.

scholarly journals Central Molecular Zone of the Milky Way: Star Formation in an extreme Environment

2015 ◽  
Vol 11 (S315) ◽  
pp. 163-166
Author(s):  
Jens Kauffmann
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Spatial Scales ◽  
Extreme Environment ◽  
Average Density ◽  
High Mass ◽  
Density Structure ◽  
Star Formation Activity ◽  
Order Of Magnitude ◽  
Sgr A

AbstractThe Central Molecular Zone (CMZ; inner ~100 pc) hosts some of the most dense and massive molecular clouds of the Milky Way. These clouds might serve as local templates for dense clouds seen in nearby starburst galaxies or in the early universe. The clouds have a striking feature: they form stars at a very slow pace, considering their mass and high average density. Here we use interferometer data from ALMA and the SMA to show that this slow star formation is a consequence of the cloud density structure: CMZ clouds have a very flat density structure. They might, for example, exceed the average density of the Orion A molecular cloud by an order of magnitude on spatial scales ~5 pc, but CMZ “cores” of ~0.1 pc radius have masses and densities lower than what is found in the Orion KL region. This absence of highest–density gas probably explains the suppression of star formation. The clouds are relatively turbulent, and ALMA observations of H2CO and SiO indicate that the turbulence is induced by high–velocity shocks. We speculate that these shocks might prevent the formation of high–mass cores. It has been argued that the state of CMZ clouds depends on their position along the orbit around Sgr A*. Our incomplete data indicate no evolution in the density structure, and only a modest evolution in star formation activity per unit mass.

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