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https://www.readbyqxmd.com/read/29352234/bi-exponential-3d-t1%C3%AF-mapping-of-whole-brain-at-3%C3%A2-t
#1
Rajiv G Menon, Azadeh Sharafi, Johannes Windschuh, Ravinder R Regatte
Detection of multiple relaxation pools using MRI is useful in a number of neuro-pathologies including multiple sclerosis (MS), Alzheimer's, and stroke. In this study we evaluate the feasibility of using T1ρ imaging for the detection of bi-exponential decays in the human brain. A prospective T1ρ imaging study was performed on model relaxation phantoms (eggs) and 7 healthy volunteers. The data was fitted using a single pool and a 2-pool model to estimate mono- and bi-exponential T1ρ maps, respectively. Bi-exponential decays were identified in the gray matter (GM) and white matter (WM) of the brain with 40...
January 19, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29351691/out-of-field-doses-in-children-treated-for-large-arteriovenous-malformations-using-hypofractionated-gamma-knife-radiosurgery-and-intensity-modulated-radiation-therapy
#2
Marijke De Saint-Hubert, Marija Majer, Hrvoje Hršak, Zdravko Heinrich, Željka Kneževic, Saveta Miljanic, Paulina Porwol, Liliana Stolarczyk, Filip Vanhavere, Roger M Harrison
The purpose of this study was to measure out-of-field organ doses in two anthropomorphic child phantoms for the treatment of large brain arteriovenous malformations (AVMs) using hypofractionated gamma knife (GK) radiosurgery and to compare these with an alternative treatment using intensity-modulated radiation therapy (IMRT). Target volume was identical in size and shape in all cases. Radiophotoluminescent (RPL), thermoluminescent (TL) and optically stimulated luminescent (OSL) dosimeters were used for out-of-field dosimetry during GK treatment and a good agreement within 1-2% between results was shown...
January 17, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29351088/fraction-variant-beam-orientation-optimization-for-non-coplanar-imrt
#3
Daniel O'Connor, Victoria Yu, Dan Nguyen, Dan Ruan, Ke Sheng
Conventional beam orientation optimization (BOO) algorithms for IMRT assume that the same set of beam angles is used for all treatment fractions. In this paper we present a BOO formulation based on group sparsity that simultaneously optimizes non-coplanar beam angles for all fractions, yielding a fraction-variant (FV) treatment plan. Beam angles are selected by solving a multi-fraction fluence map optimization problem involving 500-700 candidate beams per fraction, with an additional group sparsity term that encourages most candidate beams to be inactive...
January 19, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29350321/sliding-to-predict-vision-based-beating-heart-motion-estimation-by-modeling-temporal-interactions
#4
Angelica I Aviles-Rivero, Samar M Alsaleh, Alicia Casals
PURPOSE: Technical advancements have been part of modern medical solutions as they promote better surgical alternatives that serve to the benefit of patients. Particularly with cardiovascular surgeries, robotic surgical systems enable surgeons to perform delicate procedures on a beating heart, avoiding the complications of cardiac arrest. This advantage comes with the price of having to deal with a dynamic target which presents technical challenges for the surgical system. In this work, we propose a solution for cardiac motion estimation...
January 19, 2018: International Journal of Computer Assisted Radiology and Surgery
https://www.readbyqxmd.com/read/29350189/detection-of-thoracic-vascular-structures-by-electrical-impedance-tomography-a-systematic-assessment-of-prominence-peak-analysis-of-impedance-changes
#5
Karin Henriette Wodack, Sarah Buehler, Sarah A Nishimoto, Michael F Graessler, Christoph R Behem, Andreas Daniel Waldmann, Beat Mueller, Stephan H Böhm, Eugenijus Kaniusas, Florian Thürk, Alexander Maerz, Constantin J C Trepte, Daniel A Reuter
Electrical impedance tomography (EIT) is a noninvasive and radiation free bedside monitoring technology, primarily used to monitor lung function. First experimental data shows that the descending aorta can be detected at different thoracic heights and might allow the assessment of central hemodynamics, i.e. stroke volume and pulse transit time. Approach: First, the feasibility of localizing small non-conductive objects within a saline phantom model was evaluated. Second, this result was utilized for the detection of the aorta by EIT in ten anesthetized pigs in with comparison to thoracic computer tomography (CT)...
January 19, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29348733/monte-carlo-calculation-of-photo-neutron-dose-produced-by-circular-cones-at-18%C3%A2-mv-photon-beams
#6
Elham Hosseinzadeh, Nooshin Banaee, Hassan Ali Nedaie
Aim: The aim of this study is to calculate neutron contamination at the presence of circular cones irradiating by 18 MV photons using Monte Carlo code. Background: Small photon fields are one of the most useful methods in radiotherapy. One of the techniques for shaping small photon beams is applying circular cones made of lead. Using this method in high energy photon due to neutron contamination is a crucial issue. Materials and methods: Initially, Varian linac producing 18 MV photons was simulated and after validating the code, various circular cones were also simulated...
January 2018: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/29347251/dynamically-crowded-solutions-of-infinitely-thin-brownian-needles
#7
Sebastian Leitmann, Felix Höfling, Thomas Franosch
We study the dynamics of solutions of infinitely thin needles up to densities deep in the semidilute regime by Brownian dynamics simulations. For high densities, these solutions become strongly entangled and the motion of a needle is essentially restricted to a one-dimensional sliding in a confining tube composed of neighboring needles. From the density-dependent behavior of the orientational and translational diffusion, we extract the long-time transport coefficients and the geometry of the confining tube...
July 2017: Physical Review. E
https://www.readbyqxmd.com/read/29346298/motion-tracking-system-for-robust-non-contact-blood-perfusion-sensor
#8
Masaaki Hashimoto, Yoshihiro Taguchi
We propose a motion-robust laser Doppler flowmetry (LDF) system that can be used as a non-contact blood perfusion sensor for medical diagnosis. Endoscopic LDF systems are typically limited in their usefulness in clinical contexts by the need for the natural organs to be immobilized, as serious motion artifacts due to the axial surface displacement can interfere with blood perfusion measurements. In our system, the focusing lens moves to track the motion of the target using a low-frequency reference signal in the optical data, enabling the suppression of these motion artifacts in the axial direction...
January 18, 2018: Sensors
https://www.readbyqxmd.com/read/29346173/the-subresolution-datscan-phantom-a-cost-effective-flexible-alternative-to-traditional-phantom-technology
#9
Jonathan C Taylor, Nicholas Vennart, Ian Negus, Robin Holmes, Oliver Bandmann, Christine Lo, John Fenner
The Alderson striatal phantom is frequently used to assess I-FP-CIT (Ioflupane) image quality and to test semi-quantification software. However, its design is associated with a number of limitations, in particular: unrealistic image appearances and inflexibility. A new physical phantom approach is proposed on the basis of subresolution phantom technology. The design incorporates thin slabs of attenuating material generated through additive manufacturing, and paper sheets with radioactive ink patterns printed on their surface, created with a conventional inkjet printer...
January 17, 2018: Nuclear Medicine Communications
https://www.readbyqxmd.com/read/29346116/4d-computed-tomography-scans-for-conformal-thoracic-treatment-planning-is-a-single-scan-sufficient-to-capture-thoracic-tumor-motion
#10
Yolanda D Tseng, Landon Wootton, Matthew Nyflot, Smith Apisarnthanarax, Ramesh Rengan, Charles Bloch, George Sandison, Sara St James
Four dimensional computed tomography (4DCT) scans are routinely used in radiation therapy to determine the internal treatment volume for targets that are moving (e.g. lung tumors). The use of these studies has allowed clinicians to create target volumes based upon the motion of the tumor during the imaging study. The purpose of this work is to determine if a target volume based on a single 4DCT scan at simulation is sufficient to capture thoracic motion. Phantom studies were performed to determine expected differences between volumes contoured on 4DCT scans and those on the evaluation CT scans (slow scans)...
January 18, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29345626/accelerating-acquisition-strategies-for-low-frequency-conductivity-imaging-using-mreit
#11
Yizhuang Song, Jin Keun Seo, Munish Chauhan, Aprinda Indahlastari, Neeta Ashok Kumar, Rosalind Sadleir
We sought to improve efficiency of Magnetic Resonance Electrical Impedance Tomography data acquisition so that fast conductivity changes or electric field variations could be monitored. Undersampling of k-space was used to decrease acquisition times in spin-echo-based sequences by a factor of two. Full MREIT data were reconstructed using continuity assumptions and preliminary scans gathered without current. We found that phase data were reconstructed faithfully from undersampled data. Conductivity reconstructions of phantom data were also possible...
January 18, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29345430/wearable-wireless-tyrosinase-bandage-and-microneedle-sensors-toward-melanoma-screening
#12
Bianca Ciui, Aida Martin, Rupesh K Mishra, Barbara Brunetti, Tatsuo Nakagawa, Thomas J Dawkins, Mengjia Lyu, Cecilia Cristea, Robert Sandulescu, Joseph Wang
Wearable bendable bandage-based sensor and a minimally invasive microneedle biosensor are described toward rapid screening of skin melanoma. These wearable electrochemical sensors are capable of detecting the presence of the tyrosinase (TYR) enzyme cancer biomarker in the presence of its catechol substrate, immobilized on the transducer surface. In the presence of the surface TYR biomarker, the immobilized catechol is rapidly converted to benzoquinone that is detected amperometrically, with a current signal proportional to the TYR level...
January 18, 2018: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/29343801/dictionary-learning-based-reverberation-removal-enables-depth-resolved-photoacoustic-microscopy-of-cortical-microvasculature-in-the-mouse-brain
#13
Sushanth Govinahallisathyanarayana, Bo Ning, Rui Cao, Song Hu, John A Hossack
Photoacoustic microscopy (PAM) capitalizes on the optical absorption of blood hemoglobin to enable label-free high-contrast imaging of the cerebral microvasculature in vivo. Although time-resolved ultrasonic detection equips PAM with depth-sectioning capability, most of the data at depths are often obscured by acoustic reverberant artifacts from superficial cortical layers and thus unusable. In this paper, we present a first-of-a-kind dictionary learning algorithm to remove the reverberant signal while preserving underlying microvascular anatomy...
January 17, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29343693/phantom-acupuncture-induces-placebo-credibility-and-vicarious-sensations-a-parallel-fmri-study-of-low-back-pain-patients
#14
Meena M Makary, Jeungchan Lee, Eunyoung Lee, Seulgi Eun, Jieun Kim, Geon-Ho Jahng, Kiok Kim, You-Suk Youn, Jun-Hwan Lee, Kyungmo Park
Although acupuncture is an effective therapeutic intervention for pain reduction, the exact difference between real and sham acupuncture has not been clearly understood because a somatosensory tactile component is commonly included in the existing sham acupuncture protocols. In an event-related fMRI experiment, we implemented a novel form of sham acupuncture, phantom acupuncture, that reproduces the acupuncture needling procedure without somatosensory tactile stimulation while maintaining the credibility of the acupuncture treatment context...
January 17, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29343050/phantom-limb-pain-successfully-treated-with-scrambler-therapy
#15
Laura Fabbri, Sara P Pirotti, Marta Rosati, Nicola Ruffilli, Marco Maltoni, Marianna Ricci
No abstract text is available yet for this article.
January 17, 2018: Minerva Anestesiologica
https://www.readbyqxmd.com/read/29342291/portuguese-study-of-mean-glandular-dose-in-mammography-and-comparison-with-european-references
#16
Cláudia Sá Dos Reis, Mário João Fartaria, João H Garcia Alves, Ana Pascoal
To characterise the mean glandular dose (MGD) in a sample of healthcare providers for digital mammography in Portugal. To compare the achieved values with European references. The MGD was measured on a poly-methyl-methacrylate phantom (45 mm) for each system using dosimeters. In addition, MGD was estimated using exposure settings collected from mammography exams in clinical context. Data were collected from 25 computed-radiography systems (CR) and 13 integrated digital (DR). For both measurements (phantom and clinical exposures), the average MGD for CR was higher compared to the DR...
January 12, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29342097/time-domain-near-infrared-spectroscopy-device-for-monitoring-muscle-oxidative-metabolism-custom-probe-and-in-vivo-applications
#17
Rebecca Re, Ileana Pirovano, Davide Contini, Lorenzo Spinelli, Alessandro Torricelli
Measurement of muscle oxidative metabolism is of interest for monitoring the training status in athletes and the rehabilitation process in patients. Time domain near infrared spectroscopy (TD NIRS) is an optical technique that allows the non-invasive measurement of the hemodynamic parameters in muscular tissue: concentrations of oxy- and deoxy-hemoglobin, total hemoglobin content, and tissue oxygen saturation. In this paper, we present a novel TD NIRS medical device for muscle oxidative metabolism. A custom-printed 3D probe, able to host optical elements for signal acquisition from muscle, was develop for TD NIRS in vivo measurements...
January 17, 2018: Sensors
https://www.readbyqxmd.com/read/29341541/radiotherapy-fiber-dosimeter-probes-based-on-silver-only-coated-hollow-glass-waveguides
#18
Arash Darafsheh, Jeffrey E Melzer, James A Harrington, Alireza Kassaee, Jarod C Finlay
Manifestation of Čerenkov radiation as a contaminating signal is a significant issue in radiation therapy dose measurement by fiber-coupled scintillator dosimeters. To enhance the scintillation signal transmission while minimizing Čerenkov radiation contamination, we designed a fiber probe using a silver-only coated hollow waveguide (HWG). The HWG with scintillator inserted in its tip, embedded in tissue-mimicking phantoms, was irradiated with clinical electron and photon beams generated by a medical linear accelerator...
January 2018: Journal of Biomedical Optics
https://www.readbyqxmd.com/read/29341418/hand-held-clinical-dual-mode-ultrasound-photoacoustic-imaging-of-rat-urinary-bladder-and-its-applications
#19
Kathyayini Sivasubramanian, Vijitha Periyasamy, Rhonnie Austria Dienzo, Manojit Pramanik
Urinary bladder imaging is critical to diagnose urinary tract disorders, and bladder cancer. There is a great need for safe, non-invasive, and sensitive imaging technique which enables bladder imaging. Photoacoustic imaging is a rapidly growing imaging technique for various biological applications. It can be combined with clinical ultrasound imaging system for hand-held, dual modal ultrasound-photoacoustic real-time imaging. Structural (bladder wall) and functional (accretion of nanoparticles) bladder imaging is shown here with combined ultrasound and photoacoustic imaging in rats...
January 17, 2018: Journal of Biophotonics
https://www.readbyqxmd.com/read/29340986/comparison-of-maximal-rubidium-82-activities%C3%A2-for%C3%A2-myocardial-blood-flow-quantification-between-digital-and-conventional-pet-systems
#20
Joris D van Dijk, Pieter L Jager, Jochen A C van Osch, Maryam Khodaverdi, Jorn A van Dalen
BACKGROUND: PET-based myocardial blood flow (MBF) quantification can be inaccurate when using high tracer activities. Our aim was to derive the maximal Rubidium-82 activity for MBF assessment using a new digital PET system and compare the results with conventional analog systems. METHODS: 1.8 GBq Rubidium-82 was injected into the cardiac insert of an anthropomorphic torso phantom. Data were acquired for 10 min using an Ingenuity TF (Philips Healthcare), Discovery 690 (D690, GE Healthcare), and digital PET prototype system (Philips Healthcare)...
January 16, 2018: Journal of Nuclear Cardiology: Official Publication of the American Society of Nuclear Cardiology
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