15,323 results match your criteria Medical Physics[Journal]


Conditional random fields for phase-based lung feature tracking with ultra low-dose x-rays.

Med Phys 2019 Feb 19. Epub 2019 Feb 19.

Department of Experimental Radiation Oncology, Medical Faculty of Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.

Purpose: During radiation therapy a continuous internal tumor monitoring without additional imaging dose is desirable. In this study a sequential feature-based position estimation with ultra low-dose (ULD) kV X-rays using linear-chain conditional random fields (CRFs) is performed.

Methods: 4D-CTs of 8 patients serve as a-priori information from which ULD projections are simulated using a Monte Carlo method. Read More

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http://dx.doi.org/10.1002/mp.13447DOI Listing
February 2019

Robust CT-Ventilation from the Integral Formulation of the Jacobian.

Med Phys 2019 Feb 19. Epub 2019 Feb 19.

Department of Radiation Oncology, Beaumont Health Systems, Royal Oak, MI.

Computed tomography (CT) derived ventilation algorithms estimate the apparent voxel volume changes within an inhale/exhale CT image pair. Transformation-based methods compute these estimates solely from the spatial transformation acquired by applying a deformable image registration (DIR) algorithm to the image pair. However, approaches based on finite difference approximations of the transformation's Jacobian have been shown to be numerically unstable. Read More

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http://dx.doi.org/10.1002/mp.13453DOI Listing
February 2019

Technical note: an algorithm and software for conversion of radiotherapy contour-sequence data to ready to print 3D structures.

Med Phys 2019 Feb 18. Epub 2019 Feb 18.

Department of Oncology and Radiotherapy, Medical University of Gdansk, Gdansk, Poland.

Purpose: 3D printing is one of the most promising technologies that can significantly improve the efficiency of various radiotherapy (RT) procedures. In order to 3D print any structure from a DICOM file, it first has to be converted to one of the typical formats recognized by printing software, such as STL files. Due to the specificity of the data from RT planning systems and a lack of standardized methods, the geometry processing might be tricky and complex. Read More

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http://dx.doi.org/10.1002/mp.13452DOI Listing
February 2019

Automated Pectoral Muscle Identification on MLO-view Mammograms: Comparison of Deep Neural Network to Conventional Computer Vision.

Med Phys 2019 Feb 16. Epub 2019 Feb 16.

School of Data and Computer Science, Sun Yat-Sen University, Guangzhou, 510275, P.R. China.

Objectives: To develop a fully automated deep learning approach for identification of the pectoral muscle on mediolateral oblique (MLO) view mammograms and evaluate its performance in comparison to our previously developed texture-field orientation (TFO) method using conventional image feature analysis. Pectoral muscle segmentation is an important step for automated image analyses such as breast density or parenchymal pattern classification, lesion detection, and multi-view correlation.

Materials And Methods: Institutional Review Board (IRB) approval was obtained before data collection. Read More

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http://dx.doi.org/10.1002/mp.13451DOI Listing
February 2019
2 Reads

Quality Assurance Tasks and Tools: The Many Roles of Machine Learning.

Med Phys 2019 Feb 15. Epub 2019 Feb 15.

Department of Radiation Oncology, University of Washington Medical Center, Seattle, WA, 98195.

The recent explosion in machine learning efforts in the quality assurance (QA) space has produced a variety of proofs-of-concept many with promising results. Expected outcomes of model implementation include improvements in planning time, plan quality, advanced dosimetric QA, predictive machine maintenance, increased safety checks,and developments key for new QA paradigms driven by adaptive planning. In this article, we outline several areas of research and discuss some of the unique challenges each area presents. Read More

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http://dx.doi.org/10.1002/mp.13445DOI Listing
February 2019

Indirect methods for improving parameter estimation of PET kinetic models.

Med Phys 2019 Feb 14. Epub 2019 Feb 14.

Department of Nuclear Medicine, Chang Gung Memorial Hospital, No. 5 Fu-Shin Street, Kwei-Shan, Taoyuan County, Taiwan.

Purpose: Parametric images obtained from kinetic modeling of dynamic positron emission tomography (PET) data provide a new way of visualizing quantitative parameters of the tracer kinetics. However, due to the high noise level in pixel-wise image-driven time-activity curves, parametric images often suffer from poor quality and accuracy. In this study, we propose an indirect parameter estimation framework which aims to improve the quality and quantitative accuracy of parametric images. Read More

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http://doi.wiley.com/10.1002/mp.13448
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http://dx.doi.org/10.1002/mp.13448DOI Listing
February 2019
3 Reads

Technical Note: Simplified and practical pretherapy tumor dosimetry - A feasibility study for I-MIBG therapy of neuroblastoma using I-MIBG PET/CT.

Med Phys 2019 Feb 13. Epub 2019 Feb 13.

Department of Pediatrics, University of California, San Francisco, CA, USA.

Purpose: Radiation dose calculated on tumors for radiopharmaceutical therapy varies significantly from tumor to tumor and from patient to patient. Accurate estimation of radiation dose requires multiple time-point measurements using radionuclide imaging modalities such as SPECT or PET. In this report, we show our technical development of reducing the number of scans needed for reasonable estimation of tumor and normal organ dose in our pretherapy imaging and dosimetry platform of I-metaiodobenzylguanidine (MIBG) PET/CT for I-MIBG therapy of neuroblastoma. Read More

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http://dx.doi.org/10.1002/mp.13446DOI Listing
February 2019

Technical Note: A Comparison of Point Set Registration Methods for Electromagnetic Tracking.

Med Phys 2019 Feb 12. Epub 2019 Feb 12.

CIML, Biophysics, University of Regensburg, 93040, Regensburg, Germany.

Purpose: High dose rate brachytherapy applies intense and destruc-tive radiation. A treatment plan defines radiation source dwell positions to avoid irradiating healthy tissue. The study discusses methods to quan-tify any positional changes of source locations along the various treat-ment sessions. Read More

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http://dx.doi.org/10.1002/mp.13443DOI Listing
February 2019

A linear programming approach to inverse planning in Gamma Knife radiosurgery.

Med Phys 2019 Feb 12. Epub 2019 Feb 12.

Elekta Instrument AB, Kungstensgatan 18 Box 7593, SE-103 93, Stockholm, Sweden.

Purpose: Leksell Gamma Knife is a stereotactic radiosurgery system that allows fine-grained control of the delivered dose distribution. We describe a new inverse planning approach that both resolves shortcomings of earlier approaches and unlocks new capabilities.

Methods: We fix the isocenter positions and perform sector-duration optimization using linear programming, and study the effect of beam-on time penalization on the trade-off between beam-on time and plan quality. Read More

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http://dx.doi.org/10.1002/mp.13440DOI Listing
February 2019

Validation of Post-Treatment PET-Based Dosimetry Software for Hepatic Radioembolization of Yttrium-90 Microspheres.

Med Phys 2019 Feb 11. Epub 2019 Feb 11.

Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA.

Purpose: Yttrium-90 ( Y) microsphere radioembolization enables selective internal radiotherapy for hepatic malignancies. Currently, there is no standard post-delivery imaging and dosimetry of the microsphere distribution to verify treatment. Recent studies have reported utilizing the small positron yield of Y (32 ppm) with PET to perform treatment verification and dosimetry analysis. Read More

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http://dx.doi.org/10.1002/mp.13444DOI Listing
February 2019

Technical Note: Optimization of Spot and Trimmer Position during Dynamically Collimated Proton Therapy.

Med Phys 2019 Feb 10. Epub 2019 Feb 10.

Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, 53705.

Purpose: To demonstrate a novel theoretical optimization design which considers beam spot and trimmer positioning in addition to beamlet weighting for dynamically collimated proton therapy treatments. Prior to this, the previous methods of plan optimization used to study this emerging technology relied upon an intuitive selection criterion to fix the trimmers blades for a uniform grid of beam spots before determining the individual beamlet weights. To evaluate the potential benefit from this new optimization design, a treatment planning optimization study was performed in order to compare the algorithm's functionality against the existing methods of plan optimization. Read More

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http://dx.doi.org/10.1002/mp.13441DOI Listing
February 2019

Development of a simple numerical model for trabecular bone structures.

Med Phys 2019 Feb 10. Epub 2019 Feb 10.

Department of Medical Imaging and Radiation Sciences, Monash University, Melbourne, VIC, 3800, Australia.

Purpose: Advances in additive manufacturing processes are enabling the fabrication of surrogate bone structures for applications including use in high-resolution anthropomorphic phantoms. In this research a simple numerical model is proposed that enables the generation of microarchitecture with similar statistical distribution to trabecular bone.

Methods: A human humerus, radius, ulna, and several vertebrae were scanned on the Imaging and Medical beamline at the Australian Synchrotron and the proposed numerical model was developed through the definition of two complex functions that encode the trabecular thickness and position-dependant spacing to generate volumetric surrogate trabecular structures. Read More

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http://dx.doi.org/10.1002/mp.13435DOI Listing
February 2019

LET Response Variability of Gafchromic EBT3 Film from a Co Calibration in Clinical Proton Beam Qualities.

Med Phys 2019 Feb 10. Epub 2019 Feb 10.

Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, 53705.

Purpose: To establish a method of accurate dosimetry required to quantify the expected LET quenching effect of EBT3 film used to benchmark the dose distribution for a given treatment field and specified measurement depth. In order to facilitate this technique, a full analysis of film calibration which considers LET variability at the plane of measurement and as a function of proton beam quality is demonstrated. Additionally, the corresponding uncertainty from the process was quantified for several measurement scenarios. Read More

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http://dx.doi.org/10.1002/mp.13442DOI Listing
February 2019

Microwave-induced thermoacoustic tomography through an adult human skull.

Med Phys 2019 Feb 8. Epub 2019 Feb 8.

Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng, Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, California, 91125, USA.

Purpose: To demonstrate the feasibility of microwave-induced thermoacoustic tomography of adult human brain.

Methods: We analyzed the electric field distribution radiated from an antenna to acquire homogeneous illumination. We first imaged the anatomical structures in a rat's trunk to validate the thermoacoustic contrast in vivo. Read More

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http://doi.wiley.com/10.1002/mp.13439
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http://dx.doi.org/10.1002/mp.13439DOI Listing
February 2019
1 Read
2.635 Impact Factor

Convolutional Neural Network-based Approach for Segmentation of Left Ventricle Myocardial Scar from 3D Late Gadolinium Enhancement MR Images.

Med Phys 2019 Feb 8. Epub 2019 Feb 8.

Department of Systems and Computer Engineering, Carleton University, Ottawa, ON, Canada.

Purpose: Accurate 3-dimensional (3D) segmentation of myocardial replacement fibrosis (i.e. scar) is emerging as a potentially valuable tool for risk stratification and procedural planning in patients with ischemic cardiomyopathy. Read More

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http://dx.doi.org/10.1002/mp.13436DOI Listing
February 2019
2.635 Impact Factor

U-Net-based Deep-Learning Bladder Segmentation in CT Urography.

Med Phys 2019 Feb 8. Epub 2019 Feb 8.

School of Data and Computer Science, Sun Yat-Sen University, Guangzhou, 510275, P.R. China.

Objectives: To develop a U-Net based deep learning approach (U-DL) for bladder segmentation in computed tomography urography (CTU) as a part of a computer-assisted bladder cancer detection and treatment response assessment pipeline.

Materials And Methods: A dataset of 173 cases including 81 cases in training/validation set (42 masses, 21 with wall thickening, 18 normal bladders), and 92 cases in the test set (43 masses, 36 with wall thickening, 13 normal bladders) were used with Institutional Review Board (IRB) approval. An experienced radiologist provided 3D hand-outlines for all cases as the reference standard. Read More

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http://dx.doi.org/10.1002/mp.13438DOI Listing
February 2019

High Frame Rate Doppler Ultrasound Bandwidth Imaging for Flow Instability Mapping.

Med Phys 2019 Feb 8. Epub 2019 Feb 8.

Schlegel Research Institute for Aging and Department of Electrical & Computer Engineering, University of Waterloo, Waterloo, ON, Canada, N2L 3G1.

Purpose: Flow instability has been shown to contribute to the risk of future cardiovascular and cerebrovascular events. Nonetheless, it is challenging to non-invasively detect and identify flow instability in blood vessels. Here, we present a new framework called Doppler ultrasound bandwidth imaging (DUBI) that uses high-frame-rate ultrasound and Doppler bandwidth analysis principles to assess flow instability within an image view. Read More

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http://dx.doi.org/10.1002/mp.13437DOI Listing
February 2019

Machine Learning for Automated Quality Assurance in Radiotherapy: A Proof of Principle using EPID Data Description.

Med Phys 2019 Feb 7. Epub 2019 Feb 7.

University of Michigan, Department of Radiation Oncology, Ann Arbor, MI, 48103, United States of America.

Purpose: Developing automated methods to identify task-driven quality assurance (QA) procedures is key towards increasing safety, efficacy, and efficiency. We investigate the use of machine learning (ML) methods for possible visualization, automation and targeting of QA, and assess its performance using multi-institutional data.

Methods: To enable automated analysis of QA data given its higher dimensional nature, we used nonlinear kernel mapping with Support Vector Data Description (SVDD) driven approaches. Read More

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http://doi.wiley.com/10.1002/mp.13433
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http://dx.doi.org/10.1002/mp.13433DOI Listing
February 2019
3 Reads

Application of a directional palladium-103 brachytherapy device on a curved surface.

Med Phys 2019 Feb 8. Epub 2019 Feb 8.

Department of Radiation Oncology, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA, 19111, USA.

Purpose: The directional planar palladium-103 LDR device (CivaSheet ) may be used for intraoperative implantation at the interface between the tumor site and healthy tissue. Its dosimetric properties have been studied in the ideal case of application on a flat surface. The dosimetric impact of implanting this highly directional device on a curved surface that may be encountered in clinical treatments is analyzed. Read More

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http://dx.doi.org/10.1002/mp.13427DOI Listing
February 2019

Acknowledgment of Associate and Guest Associate Editors and Referees for Volume 45.

Authors:

Med Phys 2019 02;46(2):1093-1110

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http://dx.doi.org/10.1002/mp.13407DOI Listing
February 2019

Erratum: "The utility of quantitative CT radiomics features for improved prediction of radiation pneumonitis" [Med. Phys. Vol. 45(11):5317-5324 (2018)].

Med Phys 2019 Feb 2;46(2):1079. Epub 2019 Jan 2.

Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.

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http://dx.doi.org/10.1002/mp.13327DOI Listing
February 2019
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Comment on: Methodological accuracy of image-based electron density assessment using dual-energy computed tomography [Med. Phys. 44(6), 2429-2437 (2017)].

Authors:
Masatoshi Saito

Med Phys 2019 Feb;46(2):1075-1076

Department of Radiological Technology, Faculty of Medicine, School of Health Sciences, Niigata University, Niigata, 951-8518, Japan.

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http://dx.doi.org/10.1002/mp.13052DOI Listing
February 2019

Erratum: "Current state and future applications of radiological image guidance for particle therapy" [Med. Phys. 45:11, e1086-e1095 (2018)].

Med Phys 2019 Feb 3;46(2):1088. Epub 2019 Jan 3.

Department of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.

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http://dx.doi.org/10.1002/mp.13339DOI Listing
February 2019

A preliminary study of the local biomechanical environment of liver tumors in vivo.

Med Phys 2019 Feb 7. Epub 2019 Feb 7.

Institute for Medical Imaging Technology, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 20030, China.

Purpose: Biomechanical properties can be used as biomarkers to diagnose tumors, monitor tumor development, and evaluate treatment efficacy. The purpose of this preliminary study is to characterize the biomechanical environment of two typical liver tumors, hemangiomas (HEMs) and hepatocellular carcinomas (HCCs), and to investigate the potential of using strain metrics as biomarkers for tumor diagnosis, based on a limited clinical dataset.

Methods: Magnetic resonance (MR) tagging was used to quantify the motion and deformation of the two types of liver tumors. Read More

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http://doi.wiley.com/10.1002/mp.13434
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http://dx.doi.org/10.1002/mp.13434DOI Listing
February 2019
2 Reads

Density effects of silica aerogel insulation on the performance of a graphite probe calorimeter.

Med Phys 2019 Feb 6. Epub 2019 Feb 6.

Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada.

Purpose: With the introduction of a novel graphite probe calorimeter, called the Aerrow, various thermal insulating materials are being explored to further improve the device. Silica-based aerogels are proving to be an optimal material due to their low densities, small thermal conductivities, rigidity and machinability. The aim of this work is to determine how various silica aerogel densities affect the Aerrow's performance. Read More

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http://dx.doi.org/10.1002/mp.13426DOI Listing
February 2019

A data-efficient method for local noise power spectrum (NPS) estimation in FDK reconstructed 3D cone-beam CT.

Med Phys 2019 Feb 5. Epub 2019 Feb 5.

Division of Imaging, Diagnostics, and Software Reliability, Office of Science and Engineering Laboratories, CDRH, FDA, Silver Spring, MD, 20993.

Purpose: For CT systems in which noise is nonstationary, a local NPS is often needed to characterize its noise property. We have previously developed a data-efficient radial NPS method to estimate the two-dimensional (2D) local NPS for FBP reconstructed fan-beam CT utilizing the polar separability of CT NPS[1]. In this work we extend this method to estimate three-dimensional (3D) local NPS for FDK-reconstructed cone-beam CT (CBCT) volumes. Read More

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http://dx.doi.org/10.1002/mp.13428DOI Listing
February 2019

Removing ring artifacts in cone-beam CT via TV-Stokes and unidirectional total variation model.

Med Phys 2019 Feb 5. Epub 2019 Feb 5.

School of Science, Tianjin University, Tianjin, 300072, China.

Purpose: It often happens that cone-beam corrupted tomography (CBCT) images have some ring artifacts due to the inconsistent response of detector pixels. Removing ring artifacts in CBCT images without impairing the image quality is critical. The purpose of this study is to implement a whole new method of removing ring artifacts in CBCT images based on TV-Stokes denoising equation and unidirectional total variation (UTV). Read More

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http://dx.doi.org/10.1002/mp.13430DOI Listing
February 2019
1 Read

Exam-level dose monitoring in CT: Quality metric consideration for multiple series acquisitions.

Med Phys 2019 Feb 5. Epub 2019 Feb 5.

Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, Boston, MA, 02114, USA.

Purpose: Multi-series CT examination is common in the clinic, but no metric is agreed upon to report the overall dose from such an examination. This work proposes a relevant metric for tracking patient dose from multi-series examinations and illustrates the evaluation method through explanatory examples.

Materials And Methods: In each acquisition series, a previously reported method was used to evaluate the cross-sectional average dose along the z-axis of a water phantom, with inputs of CTDI , scan length, tube current, and patient water-equivalent diameter. Read More

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http://dx.doi.org/10.1002/mp.13431DOI Listing
February 2019
2.635 Impact Factor

Technical Note: T and T and complex permittivities of mineral oil, silicone oil, and glycerol at 0.35, 1.5, and 3 T.

Authors:
H Michael Gach

Med Phys 2019 Feb 5. Epub 2019 Feb 5.

Departments of Radiation Oncology, Radiology, and Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63110, USA.

Purpose: To identify an inexpensive, low-dielectric liquid for large magnetic resonance imaging (MRI) phantoms that can be used at multiple magnetic field strengths.

Methods: The T and T of four candidate phantom liquids (pure mineral oil, food-grade white mineral oil, silicone oil, and glycerol) with low dielectric constants were measured at three field strengths (0.35, 1. Read More

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http://dx.doi.org/10.1002/mp.13429DOI Listing
February 2019

Performance of long rectangular semi-monolithic scintillator PET detectors.

Med Phys 2019 Feb 5. Epub 2019 Feb 5.

Paul C. Lauterbur Research Centre for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.

Purpose: High-sensitivity and high-resolution depth-encoding positron emission tomography (PET) detectors are required to simultaneously improve the sensitivity and spatial resolution of a PET scanner so that the quantitative accuracy of PET studies can be improved. The semi-monolithic scintillator PET detector has the advantage of measuring the depth of interaction with single-ended readout as compared to the traditional pixelated scintillator detector, and significantly reducing the edge effect that deteriorates the spatial resolution at edges of the detector as compared to the monolithic scintillator detector if a long rectangular semi-monolithic detector is used. In this work, depth-encoding PET detector modules were built by using long rectangular semi-monolithic scintillators and single-ended readout by silicon photomultiplier (SiPM) arrays. Read More

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https://onlinelibrary.wiley.com/doi/abs/10.1002/mp.13432
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http://dx.doi.org/10.1002/mp.13432DOI Listing
February 2019
3 Reads
2.635 Impact Factor

Technical note: In silico and experimental evaluation of two leaf-fitting algorithms for MLC tracking based on exposure error and plan complexity.

Med Phys 2019 Feb 5. Epub 2019 Feb 5.

ACRF Image X Institute, Sydney Medical School, University of Sydney, Australia.

Purpose: Multi-leaf collimator (MLC) tracking is being clinically pioneered to continuously compensate for thoracic and pelvic motion during radiotherapy. The purpose of this work is to characterize the performance of two MLC leaf-fitting algorithms, direct optimization and piecewise optimization, for real-time motion compensation with different plan complexity and tumor trajectories.

Methods: To test the algorithms, both in silico and phantom experiments were performed. Read More

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http://dx.doi.org/10.1002/mp.13425DOI Listing
February 2019
2 Reads

Radiochromic EBT2 and EBT3 sensitometry based on growth of two color phases of the polymer.

Med Phys 2019 Feb 4. Epub 2019 Feb 4.

Medical Physics and Radiation Protection Service, 12 de Octubre University Hospital. Av. Cordoba, s/n, Madrid. 28041, Spain.

Purpose: The aim of this work is to develop a sensitometry model of EBT2 and EBT3 radiochromic films based on the observation that radiation induces growth of two polymer color phases.

Methods: Previously published data of the active layer absorption spectrum have been used to characterize the contribution to the total absorbance of each polymer color phase. Through a prior proposed EBT absorption spectrum model the total absorbance has been deconvolved in two polymer phase contributions. Read More

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http://dx.doi.org/10.1002/mp.13424DOI Listing
February 2019
3 Reads

An objective method to evaluate radiation dose distributions varying by three orders of magnitude.

Med Phys 2019 Feb 3. Epub 2019 Feb 3.

Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA, 70803-4001, USA.

Purpose: Modern radiotherapy practices typically report the absorbed dose (D) within the 5% relative isodose volume (i.e., the therapeutic dose region) to an accuracy of 3-5%. Read More

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http://dx.doi.org/10.1002/mp.13420DOI Listing
February 2019

Technical Note: Deriving ventilation imaging from 4DCT by deep convolutional neural network.

Med Phys 2019 Feb 3. Epub 2019 Feb 3.

Department of Radiation Oncology, University of Texas, Southwestern Medical Center.

Purpose: Ventilation images can be derived from 4DCT through analyzing the change of HU values and deformable vector fields between different respiration phases of CT. As deformable image registration (DIR) is involved, accuracy of 4DCT derived ventilation image is sensitive to the choice of DIR algorithms. To overcome the uncertainty associated with DIR, we develop a method based on deep convolutional neural network (CNN) to derive ventilation images directly from the 4DCT without explicit image registration. Read More

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http://dx.doi.org/10.1002/mp.13421DOI Listing
February 2019
2.635 Impact Factor

Interchangeability of radiomic features between [18F]-FDG PET/CT and [18F]-FDG PET/MR.

Med Phys 2019 Feb 3. Epub 2019 Feb 3.

Department of Radiation Oncology, University Hospital Zurich and University of Zurich, Zurich, 8091, Switzerland.

Purpose: Radiomics is a promising tool for identification of new prognostic biomarkers. However, image reconstruction settings and test-retest variability may influence the absolute values of radiomic features. Unstable radiomic features cannot be used as reliable biomarkers. Read More

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http://dx.doi.org/10.1002/mp.13422DOI Listing
February 2019
1 Read

Raman scattering for dosimetry using GAFCHROMIC EBT3 radiochromic dosimetry film.

Med Phys 2019 Feb 3. Epub 2019 Feb 3.

P.N. Lebedev Physical Institute of the RAS, Moscow, Russia, 119991.

Purpose: Raman scattering spectra can be thought of as the "fingerprints" of the investigated material. The purpose of this work was to link the absorbed doses of irradiated radiochromic film at the micrometer level with changes in their Raman spectra.

Methods: Raman spectra of irradiated GAFCHROMIC EBT3 film with doses ranging from 0 to 40 Gy were acquired. Read More

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http://dx.doi.org/10.1002/mp.13423DOI Listing
February 2019

Patient body motion correction for dynamic cardiac PET-CT by attenuation-emission alignment according to projection consistency conditions.

Med Phys 2019 Feb 1. Epub 2019 Feb 1.

Carleton University, 1125 Colonel By Dr, Ottawa, ON, K1S 5B6, Canada.

Introduction: Patient body motion is known to cause large deviations in the determination of myocardial blood flow (MBF) with errors exceeding 300%. Accurate correction for patient whole-body motion is still a largely unsolved problem in cardiac positron emission tomography (PET) imaging.

Objective: This study evaluated the efficacy of using Natterer's formulation of the Helgason-Ludwig consistency conditions on the two-dimensional Radon transform to align computed tomography to PET projection data in multiple time frames of a dynamic sequence for the purpose of frame-by-frame correction of rigid whole-body motion. Read More

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http://doi.wiley.com/10.1002/mp.13419
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http://dx.doi.org/10.1002/mp.13419DOI Listing
February 2019
1 Read

Two Novel PET Image Restoration Methods Guided by PET-MR Kernels: Application to Brain Imaging.

Med Phys 2019 Feb 1. Epub 2019 Feb 1.

McConnell Brain Imaging Centre, Montreal Neurological Institute, Montreal, Canada.

Purpose: Post-reconstruction PET image restoration methods that take advantage of available anatomical information can play an important role in accurate quantification of PET images. However, when using anatomical information, the resulting PET image may lose resolution in certain regions where the anatomy does not agree with the change in functional activity. In this work this problem is addressed by using both MR and filtered PET images to guide the denoising process. Read More

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http://dx.doi.org/10.1002/mp.13418DOI Listing
February 2019
1 Read

Experimental determination of the "collimator monitoring fill factor" and its relation to the error detection capabilities of various 2D-arrays.

Med Phys 2019 Feb 1. Epub 2019 Feb 1.

University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany.

Purpose: The collimator monitoring fill factor (CM-FF) introduced by Stelljes et al. (2017) and the FWHM fill factor (FWHM-FF) introduced by Gago-Arias et al. (2012) were determined using the measured photon fluence response functions of various 2D-arrays. Read More

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http://dx.doi.org/10.1002/mp.13417DOI Listing
February 2019
1 Read

Cherenkov emission-based external radiotherapy dosimetry: II. Electron beam quality specification and uncertainties.

Med Phys 2019 Jan 31. Epub 2019 Jan 31.

Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 48103-4943, USA.

Purpose: Cherenkov emission (CE) is ubiquitous in external radiotherapy. It is also unique in that it carries the promise of 3D micrometer-resolution perturbation-free in-water dosimetry with a beam quality-independent detector response calibration. Our aim is to bring CE-based dosimetry into the clinic and we motivate this here with electron beams. Read More

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http://dx.doi.org/10.1002/mp.13413DOI Listing
January 2019
3 Reads

Validation of lesion simulations in clinical CT data for anonymized chest and abdominal CT databases.

Med Phys 2019 Jan 31. Epub 2019 Jan 31.

Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, NC, 27705, USA.

Purpose: To make available to the medical imaging community a computed tomography (CT) image database composed of hybrid datasets (patient CT images with digitally inserted anthropomorphic lesions) where lesion ground truth is known a priori. It is envisioned that such a dataset could be a resource for the assessment of CT image quality, machine learning, and imaging technologies [e.g. Read More

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http://dx.doi.org/10.1002/mp.13412DOI Listing
January 2019

Deeply supervised 3D fully convolutional networks with group dilated convolution for automatic MRI prostate segmentation.

Med Phys 2019 Jan 31. Epub 2019 Jan 31.

Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, 30322, USA.

Purpose: Reliable automated segmentation of the prostate is indispensable for image-guided prostate interventions. However, the segmentation task is challenging due to inhomogeneous intensity distributions, variation in prostate anatomy, among other problems. Manual segmentation can be time-consuming and is subject to inter- and intraobserver variation. Read More

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http://dx.doi.org/10.1002/mp.13416DOI Listing
January 2019
2.635 Impact Factor

Evaluation of the Elekta Agility MLC performance using high-resolution log files.

Med Phys 2019 Jan 31. Epub 2019 Jan 31.

Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA.

Purpose: With the advent of volumetric modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) treatment techniques, the requirement for more elaborate approaches in reviewing linac components' integrity has become even more stringent. A possible solution to this challenge is to employ the usage of log files generated during treatment. The log files generated by the new generation of Elekta linacs record events at a higher frequency (25 Hz) than their predecessors, which allows for retrospective analysis and identification of subtle changes and provides another means of quality assurance. Read More

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http://dx.doi.org/10.1002/mp.13374DOI Listing
January 2019
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Artifact correction in low-dose dental CT imaging using Wasserstein generative adversarial networks.

Med Phys 2019 Jan 29. Epub 2019 Jan 29.

Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.

Purpose: In recent years, health risks concerning high-dose x-ray radiation have become a major concern in dental computed tomography (CT) examinations. Therefore, adopting low-dose computed tomography (LDCT) technology has become a major focus in the CT imaging field. One of these LDCT technologies is downsampling data acquisition during low-dose x-ray imaging processes. Read More

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http://dx.doi.org/10.1002/mp.13415DOI Listing
January 2019
2.635 Impact Factor

Gonadal shielding should be discontinued for most diagnostic imaging exams.

Med Phys 2019 Jan 29. Epub 2019 Jan 29.

Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA.

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http://dx.doi.org/10.1002/mp.13409DOI Listing
January 2019
1 Read

Derived mammographic masking measures based on simulated lesions predict the risk of interval cancer after controlling for known risk factors: a case-case analysis.

Med Phys 2019 Jan 29. Epub 2019 Jan 29.

University of Hawaii Cancer Center, Honolulu, HI, 96813, USA.

Purpose: Women with radiographically dense or texturally complex breasts are at increased risk for interval cancer, defined as cancers diagnosed after a normal screening examination. The purpose of this study was to create masking measures and apply them to identify interval risk in a population of women who experienced either screen-detected or interval cancers after controlling for breast density.

Methods: We examined full-field digital screening mammograms acquired from 2006 to 2015. Read More

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http://dx.doi.org/10.1002/mp.13410DOI Listing
January 2019
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In the future, emission-guided radiation therapy will play a critical role in clinical radiation oncology.

Med Phys 2019 Jan 29. Epub 2019 Jan 29.

Sir Peter MacCallum Cancer Institute, University of Melbourne, Melbourne, Vic., Australia.

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http://doi.wiley.com/10.1002/mp.13408
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http://dx.doi.org/10.1002/mp.13408DOI Listing
January 2019
5 Reads

Technical Note: Relative proton stopping power estimation from virtual monoenergetic images reconstructed from dual-layer computed tomography.

Med Phys 2019 Jan 29. Epub 2019 Jan 29.

Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint-Étienne, CNRS, Inserm, CREATIS, UMR 5220, U1206, F-69373, Lyon, France.

Purpose: The objective of this technical note was to investigate the accuracy of proton stopping power relative to water (RSP) estimation using a novel dual-layer, dual-energy computed tomography (DL-DECT) scanner for potential use in proton therapy planning. DL-DECT allows dual-energy reconstruction from scans acquired at a single x-ray tube voltage V by using two-layered detectors.

Methods: Sets of calibration and evaluation inserts were scanned at a DL-DECT scanner in a custom phantom with variable diameter D (0 to 150 mm) at V of 120 and 140 kV. Read More

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http://dx.doi.org/10.1002/mp.13404DOI Listing
January 2019