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https://www.readbyqxmd.com/read/27915466/impedance-and-admittance-control-for-respiratory-motion-compensation-during-robotic-needle-insertion-a-preliminary-test
#1
Yeoun Jae Kim, Jong Hyun Seo, Hong Rae Kim, Kwang Gi Kim
BACKGROUND: Many robotic needle-biopsy systems have been developed to enhance the accuracy of needle-biopsy intervention. These systems can reduce the intervention time and the radiation exposure of clinicians. However, respiratory-motion compensation is needed to ensure the accuracy and efficiency of needle biopsy intervention. METHODS: Human respiratory-motion data were acquired using three inertial measurement units (IMUs), and respiratory motion was simulated using the Stewart-Gough platform...
December 4, 2016: International Journal of Medical Robotics + Computer Assisted Surgery: MRCAS
https://www.readbyqxmd.com/read/27914781/incident-air-kerma-to-absorbed-organ-dose-conversion-factors-for-breast-and-lung-in-pa-thorax-radiography-the-effect-of-patient-thickness-and-radiation-quality
#2
A Kelaranta, P Toroi, P Vock
PURPOSE: Converting the measurable quantities to patient organ doses in projection radiography is usually based on a standard-sized patient model and a specific radiation quality, which are likely to differ from the real situation. Large inaccuracies can therefore be obtained in organ doses, because organ doses are dependent on the exposure parameters, exposure geometry and patient anatomy. In this study, the effect of radiation quality and patient thickness on the organ dose conversion factors were determined...
November 30, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27914730/quantitative-comparison-of-operative-skill-using-2-and-3-dimensional-monitors-during-laparoscopic-phantom-tasks
#3
Masayasu Nishi, Shingo Kanaji, Yoshito Otake, Hitoshi Harada, Masashi Yamamoto, Taro Oshikiri, Tetsu Nakamura, Satoshi Suzuki, Yuki Suzuki, Yuta Hiasa, Yoshinobu Sato, Yoshihiro Kakeji
BACKGROUND: The recent development of stereoscopic images using 3-dimensional monitors is expected to improve techniques for laparoscopic operation. Several studies have reported technical advantages in using 3-dimensional monitors with regard to operative accuracy and working speed, but there are few reports that analyze forceps motions by 3-dimensional optical tracking systems during standardized laparoscopic phantom tasks. We attempted to develop a 3-dimensional motion analysis system for assessing laparoscopic tasks and to clarify the efficacy of using stereoscopic images from a 3-dimensional monitor to track forceps movement during laparoscopy...
November 30, 2016: Surgery
https://www.readbyqxmd.com/read/27914403/acoustic-attenuation-imaging-of-tissue-bulk-properties-with-a-priori-information
#4
Fong Ming Hooi, Oliver Kripfgans, Paul L Carson
Attenuation of ultrasound waves traversing a medium is not only a result of absorption and scattering within a given tissue, but also of coherent scattering, including diffraction, refraction, and reflection of the acoustic wave at tissue boundaries. This leads to edge enhancement and other artifacts in most reconstruction algorithms, other than 3D wave migration with currently impractical, implementations. The presented approach accounts for energy loss at tissue boundaries by normalizing data based on variable sound speed, and potential density, of the medium using a k-space wave solver...
September 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27914043/a-revisit-to-quantitative-pet-with-18-f-fdopa-of-high-specific-activity-using-a-high-resolution-condition-in-view-of-application-to-regenerative-therapy
#5
Go Akamatsu, Akihito Ohnishi, Kazuki Aita, Hiroyuki Nishida, Yasuhiko Ikari, Masahiro Sasaki, Nobuo Kohara, Michio Senda
OBJECTIVE: With the advent of regenerative/cell therapy for Parkinson's disease (PD), (18)F-FDOPA has drawn new attention as a biomarker of the therapeutic that cannot be evaluated with radiopharmaceuticals for dopamine transporter. Since most previous (18)F-FDOPA PET studies were carried out many years ago with a PET scanner of lower resolution and with (18)F-FDOPA of low specific activity synthesized from (18)F-F2, we used a newer PET/CT scanner with a high-resolution condition and (18)F-FDOPA synthesized from (18)F-F(-) to re-evaluate this technique on normal subjects and patients with PD, together with D2 receptor imaging with (11)C-raclopride (RAC)...
December 2, 2016: Annals of Nuclear Medicine
https://www.readbyqxmd.com/read/27913343/a-frequency-shift-method-to-measure-shear-wave-attenuation-in-soft-tissues
#6
Simon Bernard, Siavash Kazemirad, Guy Cloutier
In vivo quantification of shear wave attenuation in soft tissues may help to better understand human tissue rheology and lead to new diagnostic strategies. Attenuation is difficult to measure in acoustic radiation force elastography because the shear wave amplitude decreases due to a combination of diffraction and viscous attenuation. Diffraction correction requires assuming a cylindrical wavefront and an isotropic propagation medium, which may not be the case in some applications. In this study, the frequency shift method, used in ultrasound imaging and seismology, was adapted for shear wave attenuation measurement in elastography...
December 1, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/27913340/efficient-3d-reconstruction-in-ultrasound-elastography-via-a-sparse-iteration-based-on-markov-random-fields
#7
Atul Ingle, Tomy Varghese, William Sethares
Percutaneous needle-based liver ablation procedures are becoming increasingly common for treatment of small isolated tumors in hepatocellular carcinoma patients who are not candidates for surgery. Rapid three dimensional visualization of liver ablations has potential clinical value because it can enable interventional radiologists to plan and execute needle-based ablation procedures with real time feedback. Ensuring the right volume of tissue is ablated is desirable to avoid recurrence of tumors from residual untreated cancerous cells...
November 29, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/27913107/the-influence-of-iterative-reconstruction-on-coronary-artery-calcium-scoring-phantom-and-clinical-studies
#8
Seitaro Oda, Daisuke Utsunomiya, Takeshi Nakaura, Yoshinori Funama, Hideaki Yuki, Masafumi Kidoh, Kenichiro Hirata, Narumi Taguchi, Keiichi Honda, Hiroko Takaoka, Yuji Iyama, Kazuhiro Katahira, Katsuo Noda, Shuichi Oshima, Shinichi Tokuyasu, Yasuyuki Yamashita
RATIONALE AND OBJECTIVES: We compared the effect of iterative model reconstruction (IMR), filtered back projection (FBP), and hybrid iterative reconstruction (HIR) on coronary artery calcium (CAC) scoring. MATERIALS AND METHODS: CAC scans of 30 consecutive patients (18 men and 12 women, age 70.1 ± 12.2 years) were reconstructed with FBP, HIR, and IMR, and the image noise was measured on all images. Two radiologists independently measured the CAC scores using semiautomated software, and interobserver agreement was evaluated...
November 29, 2016: Academic Radiology
https://www.readbyqxmd.com/read/27912151/euclidean-distances-as-measures-of-speaker-similarity-including-identical-twin-pairs-a-forensic-investigation-using-source-and-filter-voice-characteristics
#9
Eugenia San Segundo, Athanasios Tsanas, Pedro Gómez-Vilda
There is a growing consensus that hybrid approaches are necessary for successful speaker characterization in Forensic Speaker Comparison (FSC); hence this study explores the forensic potential of voice features combining source and filter characteristics. The former relate to the action of the vocal folds while the latter reflect the geometry of the speaker's vocal tract. This set of features have been extracted from pause fillers, which are long enough for robust feature estimation while spontaneous enough to be extracted from voice samples in real forensic casework...
November 17, 2016: Forensic Science International
https://www.readbyqxmd.com/read/27911351/evaluation-of-differential-phase-contrast-cone-beam-ct-imaging-system
#10
Jiangkun Liu, Weixing Cai, Ruola Ning
Grating-based differential phase contrast (DPC) imaging enables the use of a hospital-grade X-ray tube, but compromises the image quality due to insufficiently coherent illumination. In this research, a bench-top DPC cone beam CT (DPC-CBCT) was systematically evaluated and compared with the traditional attenuation-based CBCT in terms of contrast to noise ratio, noise property, and contrast resolution through phantom studies. In order to evaluate DPC-CBCT for soft tissue imaging, breast specimen and small animal studies were carried out...
November 30, 2016: Journal of X-ray Science and Technology
https://www.readbyqxmd.com/read/27911350/accuracy-analysis-of-intrahepatic-fat-density-measurements-using-dual-energy-computed-tomography-validation-using-a-test-phantom
#11
Tomohiro Arai, Masaki Misawa, Miki Arai, Masafumi Shinozaki, Kayo Sakamoto, Yoshinobu Yajima, Yuichi Nozaki, Tsuyoshi Tajima, Masanori Sato, Fumihiko Hinoshita
BACKGROUND: Currently, no standardized method for measuring intrahepatic fat density via conventional computed tomography (CT) exists. OBJECTIVE: We aim to quantify intrahepatic fat density via material decomposition analysis using rapid kilovolt peak-switching dual-energy (RSDE) CT. METHODS: Homogenized porcine liver and fat (lard) were mixed in various ratios to produce phantoms for fat density verification. The actual fat density was measured on the basis of the phantom volume and weight, and these measurements were used as reference densities...
November 30, 2016: Journal of X-ray Science and Technology
https://www.readbyqxmd.com/read/27910829/optimization-of-photon-beam-energies-in-gold-nanoparticle-enhanced-arc-radiation-therapy-using-monte-carlo-methods
#12
B Koger, C Kirkby
As a recent area of development in radiation therapy, gold nanoparticle (GNP) enhanced radiation therapy has shown potential to increase tumour dose while maintaining acceptable levels of healthy tissue toxicity. In this study, the effect of varying photon beam energy in GNP enhanced arc radiation therapy (GEART) is quantified through the introduction of a dose scoring metric, and GEART is compared to a conventional radiotherapy treatment. The PENELOPE Monte Carlo code was used to model several simple phantoms consisting of a spherical tumour containing GNPs (concentration: 15 mg Au g(-1) tumour, 0...
December 2, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27910825/monte-carlo-studies-on-water-and-lif-cavity-properties-for-dose-reporting-quantities-when-using-x-ray-and-brachytherapy-sources
#13
Isabela Soares Lopes Branco, Paula Cristina Guimarães Antunes, Gabriel Paiva Fonseca, Hélio Yoriyaz
Model-based dose calculation algorithms (MBDCAs) are the current tools to estimate dose in brachytherapy, which takes into account heterogeneous medium, therefore, departing from water-based formalism (TG-43). One aspect associated to MBCDA is the choice of dose specification medium since it offers two possibilities to report dose: (a) dose to medium in medium, D m,m; and (b) dose to water in medium, D w,m. The discussion about the preferable quantity to be reported is underway. The dose conversion factors, DCF, between dose to water in medium, D w,m, and dose to medium in medium, D m,m, is based on cavity theory and can be obtained using different approaches...
December 21, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27910824/accelerated-high-resolution-photoacoustic-tomography-via-compressed-sensing
#14
Simon Arridge, Paul Beard, Marta Betcke, Ben Cox, Nam Huynh, Felix Lucka, Olumide Ogunlade, Edward Zhang
Current 3D photoacoustic tomography (PAT) systems offer either high image quality or high frame rates but are not able to deliver high spatial and temporal resolution simultaneously, which limits their ability to image dynamic processes in living tissue (4D PAT). A particular example is the planar Fabry-Pérot (FP) photoacoustic scanner, which yields high-resolution 3D images but takes several minutes to sequentially map the incident photoacoustic field on the 2D sensor plane, point-by-point. However, as the spatio-temporal complexity of many absorbing tissue structures is rather low, the data recorded in such a conventional, regularly sampled fashion is often highly redundant...
December 21, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27910717/dose-optimisation-for-assessment-of-periodontal-structures-in-cone-beam-ct-examinations
#15
Ayman Al-Okshi, Chrysoula Theodorakou, Christina Lindh
OBJECTIVE: To investigate the relationship between dose and image quality for a dedicated dental Cone Beam CT (CBCT) scanner using different scanning protocols and to set up an optimal imaging protocol for assessment of periodontal structures. METHODS: Radiation dose and image quality measurements were made using the 3D Accuitomo 170 dental CBCT scanner. The SedentexCT IQ phantom was used to investigate the relationship between contrast-to-noise ratio (CNR) and dose-area product (DAP)...
December 2, 2016: Dento Maxillo Facial Radiology
https://www.readbyqxmd.com/read/27910700/evaluation-of-a-metal-artefact-reduction-tool-on-different-positions-of-a-metal-object-in-the-fov
#16
Polyane M Queiroz, Gustavo M Santaella, Thais D J da Paz, Deborah Q Freitas
OBJECTIVE: To evaluate the action of a metal artefact reduction tool when artefact-generator metal object is on different positions in the field of view (FOV). METHODS: A cylindrical utility wax phantom with a metal alloy sample inside was made. The phantom was positioned centrally and peripherally in the FOV for image acquisition, with and without the metal artefact reduction tool activation. Standard deviation values (image noise levels) from areas around the metal sample and the control area were obtained...
December 2, 2016: Dento Maxillo Facial Radiology
https://www.readbyqxmd.com/read/27910699/effect-on-measurement-accuracy-of-transillumination-using-sawtooth-shaped-function-optical-signal
#17
Xue Yang, Yajia Hu, Gang Li, Ling Lin
There exist lots of difficulties in optical transillumination of biological tissues, especially, low-level-light detection and low gray-scale resolution could reduce recognition accuracy of differences in tissue. Aiming at the problems, this paper proposes a method for optical transillumination using sawtooth-shaped-function optical signal and frame accumulation technology to explore the spatial information of heterogeneity in the tissue. Sawtooth-shaped-function optical signal combined with frame accumulation technology is applied to realize the low-level-light image detection, where frame accumulation technology improves the signal-to-noise ratio and detection sensitivity, and sawtooth-shaped-function signal improves gray-scale resolution...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910378/development-and-characterization-of-an-interferometer-for-calorimeter-based-absorbed-dose-to-water-measurements-in-a-medical-linear-accelerator
#18
Everardo Flores-Martinez, Martha J Malin, Larry A DeWerd
The quantity of relevance for external beam radiotherapy is absorbed dose to water (ADW). An interferometer was built, characterized, and tested to measure ADW within the dose range of interest for external beam radiotherapy using the temperature dependence of the refractive index of water. The interferometer was used to measure radiation-induced phase shifts of a laser beam passing through a (10 × 10 × 10) cm(3) water-filled glass phantom, irradiated with a 6 MV photon beam from a medical linear accelerator...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910330/scintillator-based-fast-ion-loss-measurements-in-the-east
#19
J F Chang, M Isobe, K Ogawa, J Huang, C R Wu, Z Xu, Z Jin, S Y Lin, L Q Hu
A new scintillator-based fast ion loss detector (FILD) has been installed on Experimental Advanced Superconducting Tokamak (EAST) to investigate the fast ion loss behavior in high performance plasma with neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH). A two dimensional 40 mm × 40 mm scintillator-coated (ZnS:Ag) stainless plate is mounted in the front of the detector, capturing the escaping fast ions. Photons from the scintillator plate are imaged with a Phantom V2010 CCD camera. The lost fast ions can be measured with the pitch angle from 60° to 120° and the gyroradius from 10 mm to 180 mm...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910001/the-effect-of-influence-quantities-and-detector-orientation-on-small-field-patient-specific-imrt-qa-comparison-of-measurements-with-various-ionization-chambers
#20
Henry Finlay Godson, Ravikumar Manickam, Sathiyan Saminathan, Kadirampatti Mani Ganesh, Retna Ponmalar
Intensity-modulated radiation therapy (IMRT) requires a patient-specific quality assurance (QA) program to validate the treatment plan and a high level of dosimetric accuracy in the treatment delivery. Dosimetric verification generally consists of both absolute- and relative-dose measurements in a phantom using ionization chambers. Measurements were carried out with three different ionization chambers (Scanditronix FC 65G, Exradin A18, and PTW PinPoint 31014) to assess the effects of influence quantities such as the stability, pre- and post-irradiation leakage, stem effect, polarity, and ion recombination on the IMRT point-dose verification with two different orientations...
December 1, 2016: Radiological Physics and Technology
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