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Radiation physics

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https://www.readbyqxmd.com/read/28346222/sign-determination-methods-for-the-respiratory-signal-in-data-driven-pet-gating
#1
Ottavia Bertolli, Simon Arridge, Scott D Wollenweber, Charles W Stearns, Brian F Hutton, Kris Thielemans
Patient respiratory motion during PET image acquisition leads to blurring in the reconstructed images and may cause significant artifacts, resulting in decreased lesion detectability, inaccurate standard uptake value calculation and incorrect treatment planning in radiation therapy. To reduce these effects data can be regrouped into (nearly) 'motion-free' gates prior to reconstruction by selecting the events with respect to the breathing phase. This gating procedure therefore needs a respiratory signal: on current scanners it is obtained from an external device, whereas with data driven (DD) methods it can be directly obtained from the raw PET data...
March 27, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28345535/photoactivated-processes-in-optical-fibers-generation-and-conversion-mechanisms-of-twofold-coordinated-si-and-ge-atoms
#2
Luigi Giacomazzi, Layla Martin-Samos, Aziz Boukenter, Youcef Ouerdane, Sylvain Girard, Antonino Alessi, Nicolas Richard, Stefano de Gironcoli
In this work we present an extensive investigation of nanoscale physical phenomena related to oxygen-deficient centers (ODC) in silica and Ge-doped silica by means of first-principles calculations, including nudged-elastic band (NEB), electron paramagnetic resonance (EPR) parameters calculations, and many-body perturbation theory (GW and Bethe-Salpeter Equation) techniques. We show that by neutralizing positively charged oxygen monovacancies we can obtain model structures of twofold Si and Ge defects of which the calculated absorption spectra and singlet-to-triplet transitions are in excellent agreement with the experimental optical absorption and photo-luminescence data...
March 27, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28344603/isobio-software-biological-dose-distribution-and-biological-dose-volume-histogram-from-physical-dose-conversion-using-linear-quadratic-linear-model
#3
Tanwiwat Jaikuna, Phatchareewan Khadsiri, Nisa Chawapun, Suwit Saekho, Ekkasit Tharavichitkul
PURPOSE: To develop an in-house software program that is able to calculate and generate the biological dose distribution and biological dose volume histogram by physical dose conversion using the linear-quadratic-linear (LQL) model. MATERIAL AND METHODS: The Isobio software was developed using MATLAB version 2014b to calculate and generate the biological dose distribution and biological dose volume histograms. The physical dose from each voxel in treatment planning was extracted through Computational Environment for Radiotherapy Research (CERR), and the accuracy was verified by the differentiation between the dose volume histogram from CERR and the treatment planning system...
February 2017: Journal of Contemporary Brachytherapy
https://www.readbyqxmd.com/read/28344599/does-ultrasound-measurement-improve-the-accuracy-of-electronic-brachytherapy-in-the-treatment-of-superficial-non-melanomatous-skin-cancer
#4
Uma Goyal, Junhan Pan, Haiyan Cui, Baldassarre Stea
PURPOSE: Electronic brachytherapy (eBT) is a form of contact radiation therapy used for thin superficial non-melanomatous skin cancers (NMSCs). An accurate measurement of diameter and depth is important for eBT treatment planning. Therefore, we compared clinical measurements by an experienced physician to measurements obtained using ultrasound (US), an objective imaging modality, in order to determine if clinical measurements were accurate enough for adequate NMSC treatment. MATERIAL AND METHODS: Eighteen patients with 20 biopsy-proven NMSCs first had a clinical examination and then an US evaluation prior to starting eBT...
February 2017: Journal of Contemporary Brachytherapy
https://www.readbyqxmd.com/read/28341967/new-organ-based-tube-current-modulation-method-to-reduce-the-radiation-dose-during-computed-tomography-of-the-head-evaluation-of-image-quality-and-radiation-dose-to-the-eyes-in-the-phantom-study
#5
Jung-Su Kim, Soon-Mu Kwon, Jung-Min Kim, Sang-Wook Yoon
A new organ-based tube current modulation (NOB-TCM) method was designed with the intent to decrease tube current by 30% over a prescribed 90° radial arc across the anterior aspect of the radiosensitive organ, without increasing tube current in the remaining radial arc. We compared a reference scan and five other dose-reducing methods with regard to effects on dose, practicality, and image quality to determine the most effective method for the reduction of the radiation dose to the eyes during CT examinations of the head...
March 24, 2017: La Radiologia Medica
https://www.readbyqxmd.com/read/28341316/what-are-appropriate-physics-manuscripts-for-submission-to-the-practical-radiation-oncology-journal
#6
EDITORIAL
Todd Pawlicki, James Chow, Sonja Dieterich, Geoffrey Hugo
No abstract text is available yet for this article.
January 20, 2017: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28341315/initial-clinical-experience-of-postmastectomy-intensity-modulated-proton-therapy-in-patients-with-breast-expanders-with-metallic-ports
#7
Robert W Mutter, Nicholas B Remmes, Mohamed Mh Kahila, Kathy A Hoeft, Deanna H Pafundi, Yan Zhang, Kimberly S Corbin, Sean S Park, Elizabeth S Yan, Valerie Lemaine, Judy C Boughey, Chris J Beltran
PURPOSE: The feasibility of proton postmastectomy radiation therapy in patients reconstructed with expanders has not been previously reported, limiting treatment options. We analyzed the dosimetric impact of the metallic port contained within expanders on intensity modulated proton therapy (IMPT) and report our techniques and quality control for treating patients in this setting. METHODS AND MATERIALS: Twelve patients with the same expander model underwent 2-field IMPT as part of a prospective registry...
December 16, 2016: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28339255/quantum-quenching-of-radiation-losses-in-short-laser-pulses
#8
C N Harvey, A Gonoskov, A Ilderton, M Marklund
Accelerated charges radiate, and therefore must lose energy. The impact of this energy loss on particle motion, called radiation reaction, becomes significant in intense-laser matter interactions, where it can reduce collision energies, hinder particle acceleration schemes, and is seemingly unavoidable. Here we show that this common belief breaks down in short laser pulses, and that energy losses and radiation reaction can be controlled and effectively switched off by appropriate tuning of the pulse length...
March 10, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28339254/efficient-vortex-generation-in-subwavelength-epsilon-near-zero-slabs
#9
Alessandro Ciattoni, Andrea Marini, Carlo Rizza
We show that a homogeneous and isotropic slab, illuminated by a circularly polarized beam with no topological charge, produces vortices of order 2 in the opposite circularly polarized components of the reflected and transmitted fields, as a consequence of the transverse magnetic and transverse electric asymmetric response of the rotationally invariant system. In addition, in the epsilon-near-zero regime, we find that vortex generation is remarkably efficient in subwavelength thick slabs up to the paraxial regime...
March 10, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28335802/use-of-low-dose-computed-tomography-to-assess-pulmonary-tuberculosis-among-healthcare-workers-in-a-tuberculosis-hospital
#10
Wei He, Bu-Dong Chen, Yan Lv, Zhen Zhou, Jin-Ping Xu, Ping-Xin Lv, Xin-Hua Zhou, Feng-Gang Ning, Cheng-Hai Li, Dong-Po Wang, Jie Zheng
BACKGROUND: According to the World Health Organization, China is one of 22 countries with serious tuberculosis (TB) infections and one of the 27 countries with serious multidrug-resistant TB strains. Despite the decline of tuberculosis in the overall population, healthcare workers (HCWs) are still at a high risk of infection. Compared with high-income countries, the TB prevalence among HCWs is higher in low- and middle-income countries. Low-dose computed tomography (LDCT) is becoming more popular due to its superior sensitivity and lower radiation dose...
March 24, 2017: Infectious Diseases of Poverty
https://www.readbyqxmd.com/read/28333688/treatment-planning-of-intensity-modulated-composite-particle-therapy-with-dose-and-linear-energy-transfer-optimization
#11
Taku Inaniwa, Nobuyuki Kanematsu, Koji Noda, Tadashi Kamada
The biological effect of charged-particle beams depends on both dose and radiation quality. The radiation quality of charged-particle beams has been most commonly represented by the linear energy transfer (LET) in radiation biology studies. We investigated a new therapeutic technique using two or more ion species in one treatment session, which we call an Intensity Modulated composite PArtiCle Therapy (IMPACT), for optimizing the physical dose and dose-averaged LET distributions in a patient as its proof of principle...
March 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28332495/single-mode-dispersive-waves-and-soliton-microcomb-dynamics
#12
Xu Yi, Qi-Fan Yang, Xueyue Zhang, Ki Youl Yang, Xinbai Li, Kerry Vahala
Dissipative Kerr solitons are self-sustaining optical wavepackets in resonators. They use the Kerr nonlinearity to both compensate dispersion and offset optical loss. Besides providing insights into nonlinear resonator physics, they can be applied in frequency metrology, precision clocks, and spectroscopy. Like other optical solitons, the dissipative Kerr soliton can radiate power as a dispersive wave through a process that is the optical analogue of Cherenkov radiation. Dispersive waves typically consist of an ensemble of optical modes...
March 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28331767/radiation-fibrosis-syndrome-imitating-breast-cancer-recurrence-a-case-report
#13
Dauren Sarsenov, Fatma Aktepe, Vahit Özmen
Nowadays, surgery, radiotherapy and chemotherapy are the most frequently used modalities in the treatment of breast cancer. It is very well-known that some severe complications may result from after these treatments. Early and late complications of radiotherapy are well known. The complications of radiation therapy may be seen in (early) or after three months (late-delayed) of periods. These complications may be related with direct or indirect effect of radiation. The radiation fibrosis syndrome is a progressive fibrotic tissue sclerosis together with various clinical symptoms in the irradiation field...
January 2017: J Breast Health (2013)
https://www.readbyqxmd.com/read/28330402/fukushima-mothers-concerns-and-associated-factors-after-the-fukushima-nuclear-power-plant-disaster
#14
Shinya Ito, Aya Goto, Kayoko Ishii, Misao Ota, Seiji Yasumura, Keiya Fujimori
This study aimed to clarify the frequency of and temporal changes in the content of mothers' free written opinions obtained in the Fukushima Health Management Survey Pregnancy and Birth Survey from 2011 to 2013. A self-administered questionnaire was mailed to women who delivered babies in Fukushima Prefecture. The questionnaire asked about maternal and child health. Expression of mothers' concerns about radiation decreased over time. Common to the top 5 codes across the 3 years were "radiation effect on fetus and infant" and "information provision including survey results...
March 2017: Asia-Pacific Journal of Public Health
https://www.readbyqxmd.com/read/28330401/pregnancy-and-birth-survey-of-the-fukushima-health-management-survey
#15
Kayoko Ishii, Aya Goto, Misao Ota, Seiji Yasumura, Keiya Fujimori
The Pregnancy and Birth Survey was started by Fukushima Medical University as part of the Fukushima Health Management Survey in 2011 in order to assess the physical and mental health of mothers and provide parenting support (telephone counseling) for those in need. The present study reviewed the major findings from 4 annual surveys conducted from 2011 to 2014. Overall proportions of preterm deliveries, low birth weight infants, and congenital anomalies in the first year were almost the same as those in national surveillance data...
March 2017: Asia-Pacific Journal of Public Health
https://www.readbyqxmd.com/read/28330398/mental-health-consequences-and-social-issues-after-the-fukushima-disaster
#16
Masaharu Maeda, Misari Oe
The Great East Japan Earthquake and subsequent nuclear power plant accident caused multidimensional and long-term effects on the mental health condition of people living in Fukushima. In this article, focusing on the influence of the nuclear disaster, we present an overview of studies regarding the psychosocial consequences of people in Fukushima. Studies revealed that the experiences of the explosions at the plant as well as the tsunami are deeply embedded in their memory, leading to posttraumatic responses...
March 2017: Asia-Pacific Journal of Public Health
https://www.readbyqxmd.com/read/28330392/from-devastation-to-recovery-and-revival-in-the-aftermath-of-fukushima-s-nuclear-power-plants-accident
#17
Hitoshi Ohto, Seiji Yasumura, Masaharu Maeda, Hiroshi Kainuma, Keiya Fujimori, Kenneth E Nollet
Japan's earthquake, tsunami, and subsequent Fukushima nuclear power plant accident in March 2011 forced the evacuation of 185 000 residents. Psychological and social impacts exacerbated by long-term evacuation and widespread rumors have influenced residents' physical and mental health, despite the fact that no direct fatalities occurred from radiation exposure. However, during the 5 years following the accident, steady recovery in industrial and economic activity has lessened previously widespread, deeply rooted stigma and self-stigma among a significant number of affected victims...
March 2017: Asia-Pacific Journal of Public Health
https://www.readbyqxmd.com/read/28330360/on-the-origin-of-stretched-exponential-kohlrausch-relaxation-kinetics-in-the-room-temperature-luminescence-decay-of-colloidal-quantum-dots
#18
E N Bodunov, Yu A Antonov, A L Simões Gamboa
The non-exponential room temperature luminescence decay of colloidal quantum dots is often well described by a stretched exponential function. However, the physical meaning of the parameters of the function is not clear in the majority of cases reported in the literature. In this work, the room temperature stretched exponential luminescence decay of colloidal quantum dots is investigated theoretically in an attempt to identify the underlying physical mechanisms associated with the parameters of the function...
March 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28328309/ibpro-a-novel-short-duration-teaching-course-in-advanced-physics-and-biology-underlying-cancer-radiotherapy
#19
Michael C Joiner, Monica W Tracey, Sara E Kacin, Jay W Burmeister
This article provides a summary and status report of the ongoing advanced education program IBPRO - Integrated course in Biology and Physics of Radiation Oncology. IBPRO is a five-year program funded by NCI. It addresses the recognized deficiency in the number of mentors available who have the required knowledge and skill to provide the teaching and training that is required for future radiation oncologists and researchers in radiation sciences. Each year, IBPRO brings together 50 attendees typically at assistant professor level and upwards, who are already qualified/certified radiation oncologists, medical physicists or biologists...
March 22, 2017: Radiation Research
https://www.readbyqxmd.com/read/28327297/first-proof-of-bismuth-oxide-nanoparticles-as-efficient-radiosensitisers-on-highly-radioresistant-cancer-cells
#20
Callum Stewart, Konstantin Konstantinov, Sally McKinnon, Susanna Guatelli, Michael Lerch, Anatoly Rosenfeld, Moeava Tehei, Stéphanie Corde
This study provides the first proof of the novel application of bismuth oxide as a radiosensitiser. It was shown that on the highly radioresistant 9L gliosarcoma cell line, bismuth oxide nanoparticles sensitise to both kilovoltage (kVp) or megavoltage (MV) X-rays radiation. 9L cells were exposed to a concentration of 50μg.mL(-1) of nanoparticle before irradiation at 125kVp and 10MV. Sensitisation enhancement ratios of 1.48 and 1.25 for 125kVp and 10MV were obtained in vitro, respectively. The radiation enhancement of the nanoparticles is postulated to be a combination of the high Z nature of the bismuth (Z=83), and the surface chemistry...
November 2016: Physica Medica: PM
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