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Title: Exposing the dead cone effect with jet substructure techniques

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1324489
Grant/Contract Number:
SC-00012567; SC-0006389
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 94; Journal Issue: 5; Related Information: CHORUS Timestamp: 2016-09-14 18:11:16; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Maltoni, Fabio, Selvaggi, Michele, and Thaler, Jesse. Exposing the dead cone effect with jet substructure techniques. United States: N. p., 2016. Web. doi:10.1103/PhysRevD.94.054015.
Maltoni, Fabio, Selvaggi, Michele, & Thaler, Jesse. Exposing the dead cone effect with jet substructure techniques. United States. doi:10.1103/PhysRevD.94.054015.
Maltoni, Fabio, Selvaggi, Michele, and Thaler, Jesse. 2016. "Exposing the dead cone effect with jet substructure techniques". United States. doi:10.1103/PhysRevD.94.054015.
@article{osti_1324489,
title = {Exposing the dead cone effect with jet substructure techniques},
author = {Maltoni, Fabio and Selvaggi, Michele and Thaler, Jesse},
abstractNote = {},
doi = {10.1103/PhysRevD.94.054015},
journal = {Physical Review D},
number = 5,
volume = 94,
place = {United States},
year = 2016,
month = 9
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevD.94.054015

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  • Purpose: Dead detectors due to manufacturing defects or radiation damage in the electronic portal imaging devices (EPIDs) used for cone-beam computed tomography (CBCT) can lead to image degradation and ring artifacts. In this work three dead detector correction methods were assessed using megavoltage CBCT (MVCBCT) as a test system, with the goals of assessing the relative effectiveness of the three methods and establishing the conditions for which they fail. Methods: MVCBCT projections acquired with four linacs at 8 and 60 MU (monitor units) were degraded with varying percentages (2%-95%) of randomly distributed dead single detectors (RDSs), randomly distributed dead detectormore » clusters (RDCs) of 2 mm diameter, and nonrandomly distributed dead detector disks (NRDDs) of varying diameter (4-16 mm). Correction algorithms were bidirectional linear interpolation (BLI), quad-directional linear interpolation (QLI), and a Laplacian solution (LS) method. Correction method failure was defined to occur if ring artifacts were present in the reconstructed phantom images from any linac or if the modulation transfer function (MTF) for any linac dropped below baseline with a p value, calculated with the two sample t test, of less than 0.01. Results: All correction methods failed at the same or lower RDC/RDS percentages and NRDD diameters for the 60 MU as for the 8 MU cases. The LS method tended to outperform or match the BLI and QLI methods. If ring artifacts anywhere in the images were considered unacceptable, the LS method failed for 60 MU at >33% RDS, >2% RDC, and >4 mm NRDD. If ring artifacts within 4 mm longitudinally of the phantom section interfaces were considered acceptable, the LS method failed for 60 MU at >90% RDS, >80% RDC, and >4 mm NRDD. LS failed due to MTF drop for 60 MU at >50% RDS, >25% RDC, and >4 mm NRDD. Conclusions: The LS method is superior to the BLI and QLI methods, and correction algorithm effectiveness decreases as imaging dose increases. All correction methods failed first due to ring artifacts and second due to MTF drop. If ring artifacts in axial slices within a 4 mm longitudinal distance from phantom section interfaces are acceptable, statistically significant loss in spatial resolution does not occur until over 25% of the EPID is covered in randomly distributed dead detectors, or NRDDs of 4 mm diameter are present.« less
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  • Research-based procedures for characterizing the causes of elevated indoor 222Rn levels and guiding the selection of an appropriate control technique were evaluated at seven New Jersey houses. Procedures such as thorough visual inspections, blower door air leakage tests, pressure field mapping, subsurface vacuum extension tests, sampling of 222Rn concentrations throughout the substructure, and measurements of the additional depressurization caused by various appliances all were found to furnish important information to the mitigation contractor or researcher. An analysis of data from these and other diagnostic techniques performed at the seven houses also indicated: (1) regions of very high permeability existed directlymore » adjacent to the exterior of substructure walls and floors; (2) the additional substructure depressurization caused by operation of forced-air furnaces and attic exhaust fans could exceed 1 Pascal; (3) 222Rn concentrations below basement slabs and slabs-on-grade adjoining below grade basement walls were approximately seven times higher than those within block wall cavities; and (4) air leakage areas of crawlspace and basement ceilings were quite large, ranging up to 0.15 m2. The pressure field mapping tests identified the areas surrounding the substructure that were well coupled to the indoors. Using flow, pressure difference, and 222Rn concentration data, indices of soil gas entry potential and 222Rn entry potential were developed to indicate the areas of the substructure that may have high entry rates of soil gas and 222Rn, respectively. These indices could be helpful for quantifying the relative resistance to soil gas movement of substructure surfaces and surrounding soils and for determining the placement of 222Rn control systems.« less