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Australasian Physical & Engineering Sciences in Medicine

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https://www.readbyqxmd.com/read/28220403/dosimetry-in-mars-spectral-ct-topas-monte-carlo-simulations-and-ion-chamber-measurements
#1
Gray Lu, Steven Marsh, Jerome Damet, Pierre Carbonez, John Laban, Christopher Bateman, Anthony Butler, Phil Butler
Spectral computed tomography (CT) is an up and coming imaging modality which shows great promise in revealing unique diagnostic information. Because this imaging modality is based on X-ray CT, it is of utmost importance to study the radiation dose aspects of its use. This study reports on the implementation and evaluation of a Monte Carlo simulation tool using TOPAS for estimating dose in a pre-clinical spectral CT scanner known as the MARS scanner. Simulated estimates were compared with measurements from an ionization chamber...
February 20, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28220402/the-specific-absorption-rate-of-tissues-in-rats-exposed-to-electromagnetic-plane-waves-in-the-frequency-range-of-0-05-5%C3%A2-ghz-and-sarwb-in-free-moving-rats
#2
Bingxin Chen, Jiamin Wang, Hongxin Qi, Jie Zhang, Shude Chen, Xianghui Wang
As electromagnetic exposure experiments can only be performed on small animals, usually rats, research on the characteristics of specific absorption rate (SAR) distribution in the rat has received increasing interest. A series of calculations, which simulated the SAR in a male rat anatomical model exposed to electromagnetic plane waves ranging from 0.05 to 5 GHz with different incidence and polarization, were conducted. The whole-body-averaged SAR (SARwb) and the tissue-averaged SAR (SARavg) in 20 major tissues were determined...
February 20, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28220401/numerical-model-for-healthy-and-injured-ankle-ligaments
#3
Antonella Forestiero, Emanuele Luigi Carniel, Chiara Giulia Fontanella, Arturo Nicola Natali
The aim of this work is to provide a computational tool for the investigation of ankle mechanics under different loading conditions. The attention is focused on the biomechanical role of ankle ligaments that are fundamental for joints stability. A finite element model of the human foot is developed starting from Computed Tomography and Magnetic Resonance Imaging, using particular attention to the definition of ankle ligaments. A refined fiber-reinforced visco-hyperelastic constitutive model is assumed to characterize the mechanical response of ligaments...
February 20, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28220400/winning-images-from-the-photography-in-medical-physics-pimp-competition-radiation-signage-in-sight-%C3%A2-james-rijken-adelaide-radiotherapy-centre
#4
(no author information available yet)
No abstract text is available yet for this article.
February 20, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28210991/extraction-of-fetal-ecg-signal-by-an-improved-method-using-extended-kalman-smoother-framework-from-single-channel-abdominal-ecg-signal
#5
D Panigrahy, P K Sahu
This paper proposes a five-stage based methodology to extract the fetal electrocardiogram (FECG) from the single channel abdominal ECG using differential evolution (DE) algorithm, extended Kalman smoother (EKS) and adaptive neuro fuzzy inference system (ANFIS) framework. The heart rate of the fetus can easily be detected after estimation of the fetal ECG signal. The abdominal ECG signal contains fetal ECG signal, maternal ECG component, and noise. To estimate the fetal ECG signal from the abdominal ECG signal, removal of the noise and the maternal ECG component presented in it is necessary...
February 16, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28210990/indices-from-lagged-poincare-plots-of-heart-rate-variability-an-efficient-nonlinear-tool-for-emotion-discrimination
#6
Ateke Goshvarpour, Ataollah Abbasi, Atefeh Goshvarpour
Interest in human emotion recognition, regarding physiological signals, has recently risen. In this study, an efficient emotion recognition system, based on geometrical analysis of autonomic nervous system signals, is presented. The electrocardiogram recordings of 47 college students were obtained during rest condition and affective visual stimuli. Pictures with four emotional contents, including happiness, peacefulness, sadness, and fear were selected. Then, ten lags of Poincare plot were constructed for heart rate variability (HRV) segments...
February 16, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28197889/addendum-to-39-1-special-section-medical-imaging-and-insights-into-the-mechanics-of-heart-and-circulatory-physiology-and-dysfunction
#7
Martin Caon
No abstract text is available yet for this article.
February 14, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28194655/practical-time-considerations-for-optically-stimulated-luminescent-dosimetry-osld-in-total-body-irradiation
#8
Martin Butson, Mamoon Haque, Leon Smith, Ethan Butson, David Odgers, Dane Pope, Tina Gorjiana, May Whitaker, Johnny Morales, Angela Hong, Robin Hill
Total body irradiation (TBI) treatments are used to treat the whole body in preparation for hematopoietic stem cell (or bone marrow) transplantation. Our standard clinical regimen is a 12 Gy in 6 fraction, bi-daily technique using 6 MV X-rays at an extended Source-to-Surface distance (SSD) of 300 cm. Utilizing these characteristics, the beam dose rate is reduced below 7 cGy/min as is standard for TBI treatment. Dose received by the patient is monitored using optically stimulated luminescent dosimetry (OSLD)...
February 13, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28168587/improving-the-quality-of-reconstructed-x-ray-ct-images-of-polymer-gel-dosimeters-zero-scan-coupled-with-adaptive-mean-filtering
#9
M B Kakakhel, A Jirasek, H Johnston, T Kairn, J V Trapp
This study evaluated the feasibility of combining the 'zero-scan' (ZS) X-ray computed tomography (CT) based polymer gel dosimeter (PGD) readout with adaptive mean (AM) filtering for improving the signal to noise ratio (SNR), and to compare these results with available average scan (AS) X-ray CT readout techniques. NIPAM PGD were manufactured, irradiated with 6 MV photons, CT imaged and processed in Matlab. AM filter for two iterations, with 3 × 3 and 5 × 5 pixels (kernel size), was used in two scenarios (a) the CT images were subjected to AM filtering (pre-processing) and these were further employed to generate AS and ZS gel images, and (b) the AS and ZS images were first reconstructed from the CT images and then AM filtering was carried out (post-processing)...
February 6, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28168586/they-tamed-the-photon-early-days-of-radiation-dosimetry
#10
John R Patterson
This article is a tribute to the many physicists who tamed the photon in the service of mankind. Many received Nobel Prizes and other high awards. Several have units named after them. Some invented the equipment we use. Some sacrificed their lives before the hazards and benefits of radiation were fully understood. I discuss the progress over 120 years, both theoretical and technical, in the development of radiation protection regulations based on quantitative measurements and a consistent set of units, the gray and sievert...
February 6, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28168585/variation-of-flow-rate-and-angle-of-injected-venous-needle%C3%A2-on-influencing-intimal-hyperplasia-at-the-venous-anastomosis-of-the-hemodialysis-graft
#11
Linqiang Yang, Aijun Yin, Wanqian Liu
During hemodialysis, arteriovenous (AV) grafts tends to result in intimal hyperplasia (IH) at the venous anastomosis which leads to graft failure. It is well documented that hemodynamic factors have been implicated in IH, as well as pathogenesis of graft stenosis. In this paper, we investigate the flow rate and angle of injection of a venous needle on damaging the hemodialysis graft. Such damage is mainly caused by hemodynamics rather than the actual physical puncture of the needle. By computational fluid dynamic analysis of flow through the AV grafts, we demonstrate that slower flow rate of the needle preserve a larger region of low wall shear stress (WSS)...
February 6, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28124771/development-and-verification-of-a-time-delivery-model-for-prostate-intensity-modulated-radiotherapy-using-a-siemens-%C3%A2-artiste%C3%A2-160-multi-leaf-collimator-linac
#12
Nicola Fourie, Omer A Ali, William I D Rae
Time delivery models thus far proposed for prediction of radiotherapy delivery times are not applicable to all makes of Linac. Our purpose was to develop a time delivery model, which would also be applicable for a Siemens(®) ARTISTE™ 160 Multi-leaf Collimator (MLC) linear accelerator (Linac) and validate the model using prostate Intensity Modulated Radiation Therapy (IMRT) treatment plans. To our knowledge, a time delivery model has not yet been proposed for a Siemens(®) ARTISTE™ 160 MLC Linac. We used the principles of the time delivery model created for a Varian(®) Linac and added the radio frequency (RF) wave component, and the MLC delay time to the MLC travel time component...
January 26, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28120144/predicting-prostate-tumour-location-from-multiparametric-mri-using-gaussian-kernel-support-vector-machines-a-preliminary-study
#13
Yu Sun, Hayley Reynolds, Darren Wraith, Scott Williams, Mary E Finnegan, Catherine Mitchell, Declan Murphy, Martin A Ebert, Annette Haworth
The performance of a support vector machine (SVM) algorithm was investigated to predict prostate tumour location using multi-parametric MRI (mpMRI) data. The purpose was to obtain information of prostate tumour location for the implementation of bio-focused radiotherapy. In vivo mpMRI data were collected from 16 patients prior to radical prostatectomy. Sequences included T2-weighted imaging, diffusion-weighted imaging and dynamic contrast enhanced imaging. In vivo mpMRI was registered with 'ground truth' histology, using ex vivo MRI as an intermediate registration step to improve accuracy...
January 24, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28116639/localized-atlas-based-segmentation-of-breast-mri-in-a-decision-making-framework
#14
Aida Fooladivanda, Shahriar B Shokouhi, Nasrin Ahmadinejad
Breast-region segmentation is an important step for density estimation and Computer-Aided Diagnosis (CAD) systems in Magnetic Resonance Imaging (MRI). Detection of breast-chest wall boundary is often a difficult task due to similarity between gray-level values of fibroglandular tissue and pectoral muscle. This paper proposes a robust breast-region segmentation method which is applicable for both complex cases with fibroglandular tissue connected to the pectoral muscle, and simple cases with high contrast boundaries...
January 23, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28105540/echocardiographic-assessment-of-long-term-hemodynamic-characteristics-of-mechanical-mitral-valve-prostheses-with-different-mitral-valvular-diseases
#15
Xiliang Zhu, Qian Li, Hong Tang, Xijun Xiao
Mitral stenosis (MS) and mitral insufficiency (MI) have different pre-operative hemodynamic characteristics. However, it is unclear if there are differences in long-term echocardiographic characteristics of MS and MI patients after mechanical mitral valve replacement. This study is to compare long-term echocardiographic results of mechanical mitral valve prostheses between MS and MI patients. From January 2003 to January 2009, a total of 199 consecutive patients were recruited in this study. Patients were classified as group MS (n = 123) and MI (n = 76) according to the manifestation of mitral valvular disease...
January 19, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28083852/dna-sensors-to-assess-the-effect-of-vkorc1-and-cyp2c9-gene-polymorphisms-on-warfarin-dose-requirement-in-chinese-patients-with-atrial-fibrillation
#16
Tao-Sheng Huang, Ling Zhang, Qiong He, Yu-Bin Li, Zhong-Li Dai, Jian-Rui Zheng, Pei-Qi Cheng, Yun-Shao He
The optimal dose of warfarin depends on polymorphisms in the VKORC1 (the vitamin K epoxide reductase complex subunit (1) and CYP2C9 (cytochrome P450 2C9) genes. To minimize the risk of adverse reactions, warfarin dosages should be adjusted according to results from rapid and simple monitoring methods. However, there are few pharmacogenetic-guided warfarin dosing algorithms that are based on large cohorts from the Chinese population, especially patients with atrial fibrillation. This study aimed to validate a pharmacogenetic-guided warfarin dosing algorithm based on results from a new rapid electrochemical detection method used in a multicenter study...
January 12, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28083851/the-influence-of-the-dose-calculation-resolution-of-vmat-plans-on-the-calculated-dose-for-eye-lens-and-optic-pathway
#17
Jong Min Park, So-Yeon Park, Jung-In Kim, Joel Carlson, Jin Ho Kim
To investigate the effect of dose calculation grid on calculated dose-volumetric parameters for eye lenses and optic pathways. A total of 30 patients treated using the volumetric modulated arc therapy (VMAT) technique, were retrospectively selected. For each patient, dose distributions were calculated with calculation grids ranging from 1 to 5 mm at 1 mm intervals. Identical structures were used for VMAT planning. The changes in dose-volumetric parameters according to the size of the calculation grid were investigated...
January 12, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28070749/an-automated-microemboli-detection-and-classification-system-using-backscatter-rf-signals-and-differential-evolution
#18
Karim Ferroudji, Nabil Benoudjit, Ayache Bouakaz
Embolic phenomena, whether air or particulate emboli, can induce immediate damages like heart attack or ischemic stroke. Embolus composition (gaseous or particulate matter) is vital in predicting clinically significant complications. Embolus detection using Doppler methods have shown their limits to differentiate solid and gaseous embolus. Radio-frequency (RF) ultrasound signals backscattered by the emboli contain additional information on the embolus in comparison to the traditionally used Doppler signals...
January 9, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28035635/ecg-signal-denoising-via-empirical-wavelet-transform
#19
Omkar Singh, Ramesh Kumar Sunkaria
This paper presents new methods for baseline wander correction and powerline interference reduction in electrocardiogram (ECG) signals using empirical wavelet transform (EWT). During data acquisition of ECG signal, various noise sources such as powerline interference, baseline wander and muscle artifacts contaminate the information bearing ECG signal. For better analysis and interpretation, the ECG signal must be free of noise. In the present work, a new approach is used to filter baseline wander and power line interference from the ECG signal...
December 29, 2016: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28005238/comparison-between-x-rays-spectra-and-their-effective-energies-in-small-animal-ct-tomographic-imaging-and-dosimetry
#20
Mahdjoub Hamdi, Malika Mimi, M'hamed Bentourkia
Small animal CT imaging and dosimetry usually rely on X-ray radiation produced by X-ray tubes. These X-rays typically cover a large energy range. In this study, we compared poly-energetic X-ray spectra against estimated equivalent (effective) mono-energetic beams with the same number of simulated photons for small animal CT imaging and dosimetry applications. Two poly-energetic X-ray spectra were generated from a tungsten anode at 50 and 120 kVp. The corresponding effective mono-energetic beams were established as 36 keV for the 50 kVp spectrum and 49...
December 22, 2016: Australasian Physical & Engineering Sciences in Medicine
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