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Physica Medica: PM

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https://www.readbyqxmd.com/read/29747928/monte-carlo-simulation-tool-for-online-treatment-monitoring-in-hadrontherapy-with-in-beam-pet-a-patient-study
#1
E Fiorina, V Ferrero, F Pennazio, G Baroni, G Battistoni, N Belcari, P Cerello, N Camarlinghi, M Ciocca, A Del Guerra, M Donetti, A Ferrari, S Giordanengo, G Giraudo, A Mairani, M Morrocchi, C Peroni, A Rivetti, M D Da Rocha Rolo, S Rossi, V Rosso, P Sala, G Sportelli, S Tampellini, F Valvo, R Wheadon, M G Bisogni
Hadrontherapy is a method for treating cancer with very targeted dose distributions and enhanced radiobiological effects. To fully exploit these advantages, in vivo range monitoring systems are required. These devices measure, preferably during the treatment, the secondary radiation generated by the beam-tissue interactions. However, since correlation of the secondary radiation distribution with the dose is not straightforward, Monte Carlo (MC) simulations are very important for treatment quality assessment...
May 7, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29724659/geant4-implementation-of-inter-atomic-interference-effect-in-small-angle-coherent-x-ray-scattering-for-materials-of-medical-interest
#2
G Paternò, P Cardarelli, A Contillo, M Gambaccini, A Taibi
An extension to Geant4 Monte Carlo code was developed to take into account inter-atomic (molecular) interference effects in X-ray coherent scattering. Based on our previous works, the developed code introduces a set of form factors including interference effects for a selected variety of amorphous materials useful for medical applications, namely various tissues and plastics used to build phantoms. The code is easily upgradable in order to include new materials and offers the possibility to model a generic tissue as a combination of a set of four basic components...
April 30, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29705184/homogeneous-vs-patient-specific-breast-models-for-monte-carlo-evaluation-of-mean-glandular-dose-in-mammography
#3
A Sarno, G Mettivier, F Di Lillo, K Bliznakova, I Sechopoulos, P Russo
PURPOSE: To compare, via Monte Carlo simulations, homogeneous and non-homogenous breast models adopted for mean glandular dose (MGD) estimates in mammography vs. patient specific digital breast phantoms. METHODS: We developed a GEANT4 Monte Carlo code simulating four homogenous cylindrical breast models featured as follows: (1) semi-cylindrical section enveloped in a 5-mm adipose layer; (2) semi-elliptical section with a 4-mm thick skin; (3) semi-cylindrical section with a 1...
April 25, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29699921/monte-carlo-study-of-out-of-field-exposure-in-carbon-ion-radiotherapy-with-a-passive-beam-organ-doses-in-prostate-cancer-treatment
#4
Shunsuke Yonai, Naruhiro Matsufuji, Keiichi Akahane
PURPOSE: The aim of this work was to estimate typical dose equivalents to out-of-field organs during carbon-ion radiotherapy (CIRT) with a passive beam for prostate cancer treatment. Additionally, sensitivity analyses of organ doses for various beam parameters and phantom sizes were performed. METHODS: Because the CIRT out-of-field dose depends on the beam parameters, the typical values of those parameters were determined from statistical data on the target properties of patients who received CIRT at the Heavy-Ion Medical Accelerator in Chiba (HIMAC)...
April 23, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29685425/pre-treatment-verification-of-lung-sbrt-vmat-plans-with-delivery-errors-toward-a-better-understanding-of-the-gamma-index-analysis
#5
Thahabah Alharthi, Elise M Pogson, Sankar Arumugam, Lois Holloway, David Thwaites
PURPOSE: To study the sensitivity of the ArcCHECK in detecting delivery errors for lung stereotactic body radiotherapy (SBRT) using the Volumetric Modulated Arc Therapy (VMAT) technique and to evaluate the sensitivity of eight global and local gamma tolerances with different cut-off percentages. METHODS: Baseline VMAT plans were generated for 15 lung SBRT patients. We delivered the smallest errors(gantry, collimator, and multileaf collimator MLC) which had ≥ ±2% dose difference in the modified treatment plans compared to the baseline plan (the clinical significance of those errors were assessed in our previous study...
April 20, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29673742/skin-models-and-their-impact-on-mean-glandular-dose-in-mammography
#6
Rodrigo Trevisan Massera, Alessandra Tomal
PURPOSE: To quantify the influence of different skin models on mammographic breast dosimetry, based on dosimetric protocols and recent breast skin thickness findings. METHODS: By using an adapted PENELOPE (v. 2014) + PenEasy (v. 2015) Monte Carlo (MC) code, simulations were performed in order to obtain the mean glandular dose (MGD), the normalized MGD by incident air Kerma (DgN), and the glandular depth dose (GDD(z)). The geometry was based on a cranio-caudal mammographic examination...
April 16, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29655921/efomp-policy-statement-16-the-role-and-competences-of-medical-physicists-and-medical-physics-experts-under-2013-59-euratom
#7
Carmel J Caruana, Virginia Tsapaki, John Damilakis, Marco Brambilla, Guadalupe Martín Martín, Asen Dimov, Hilde Bosmans, Gillian Egan, Klaus Bacher, Brendan McClean
On 5 December 2013 the European Council promulgated Directive 2013/59/EURATOM. This Directive is important for Medical Physicists and Medical Physics Experts as it puts the profession on solid foundations and describes it more comprehensively. Much commentary regarding the role and competences has been developed in the context of the European Commission project "European Guidelines on the Medical Physics Expert" published as Radiation Protection Report RP174. The guidelines elaborate on the role and responsibilities under 2013/59/EURATOM in terms of a mission statement and competence profile in the specialty areas of Medical Physics relating to medical radiological services, namely Diagnostic and Interventional Radiology, Radiation Oncology and Nuclear Medicine...
April 11, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29631867/the-use-of-out-of-plane-high-z-patient-shielding-for-fetal-dose-reduction-in-computed-tomography-literature-review-and-comparison-with-monte-carlo-calculations-of-an-alternative-optimisation-technique
#8
Nick Ryckx, Marta Sans-Merce, Sabine Schmidt, Pierre-Alexandre Poletti, Francis R Verdun
When performing CT examinations on pregnant patients, great effort should be dedicated towards optimising the exposure of the mother and the conceptus. For this purpose, many radiology departments use high-Z garments to be wrapped around the patient's lower abdomen for out-of-plane organ shielding to protect the fetus. To assess their current protection efficiency, we performed a literature review and compared the efficiencies mentioned in the literature to Monte-Carlo calculations of CT protocols for which the overall scan length was reduced...
April 6, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29628360/mechanistic-dna-damage-simulations-in-geant4-dna-part-1-a-parameter-study-in-a-simplified-geometry
#9
Nathanael Lampe, Mathieu Karamitros, Vincent Breton, Jeremy M C Brown, Ioanna Kyriakou, Dousatsu Sakata, David Sarramia, Sébastien Incerti
Mechanistic modelling of DNA damage in Monte Carlo simulations is highly sensitive to the parameters that define DNA damage. In this work, we use a simple testing geometry to investigate how different choices of physics models and damage model parameters can change the estimation of DNA damage in a mechanistic DNA damage simulation built in Geant4-DNA. The choice of physics model can lead to variations by up to a factor of two in the yield of physically induced strand breaks, and the parameters that determine scavenging, and physical and chemical single strand break induction can have even larger consequences...
April 5, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29599081/improvement-of-early-detection-of-breast-cancer-through-collaborative-multi-country-efforts-medical-physics-component
#10
Patricia Mora, Keith Faulkner, Ahmed M Mahmoud, Vesna Gershan, Aruna Kausik, Urban Zdesar, María-Ester Brandan, Serap Kurt, Jasna Davidović, Dina H Salama, Erkin Aribal, Clara Odio, Arvind K Chaturvedi, Zahida Sabih, Saša Vujnović, Diana Paez, Harry Delis
PURPOSE: The International Atomic Energy Agency (IAEA) through a Coordinated Research Project on "Enhancing Capacity for Early Detection and Diagnosis of Breast Cancer through Imaging", brought together a group of mammography radiologists, medical physicists and radiographers; to investigate current practices and improve procedures for the early detection of breast cancer by strengthening both the clinical and medical physics components. This paper addresses the medical physics component...
March 26, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29576466/william-henry-bragg-man-and-scientist-nobel-laureate-and-first-professor-of-physics-university-of-adelaide-1886-1909
#11
EDITORIAL
John Patterson, Robert George
In London, November 1915, a telegram was received at the home of William Henry Bragg from the secretary of the Academy of Science in Stockholm announcing the award of the Nobel Prize in Physics for "the analysis of crystal structures by means of X-rays". A second similar telegram was addressed to his 25 year old son William Lawrence Bragg (Jenkin, 2008). This article commemorates the centenary of that event and the unveiling of a bust of Sir William Bragg alongside that of his son, Sir Lawrence Bragg, on North Terrace in Adelaide where he spent 23 years of his early career...
March 22, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29572112/an-automated-monte-carlo-qc-system-for-volumetric-modulated-arc-therapy-possibilities-and-challenges
#12
R Chakarova, R Cronholm, M Krantz, P Andersson, A Hallqvist
PURPOSE: To develop and implement an automated Monte Carlo (MC) system for patient specific VMAT quality control in a patient geometry that generates treatment planning system (TPS) compliant DICOM objects and includes a module for 3D analysis of dose deviations. Also, the aims were to recommend diagnose specific tolerance criteria and an evaluation procedure. METHODS: The EGSnrc code package formed the basis for development of the MC system. The workflow consists of a number of modules connected to a TPS by means of manual DICOM exports and imports which were executed sequentially without user interaction...
March 20, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29728235/optimization-based-region-of-interest-reconstruction-for-x-ray-computed-tomography-based-on-total-variation-and-data-derivative
#13
Ailong Cai, Lei Li, Linyuan Wang, Bin Yan, Zhizhong Zheng, Hanming Zhang, Guoen Hu
Region-of-interest (ROI) and interior reconstructions for computed tomography (CT) have drawn much attention and can be of practical value for potential applications in reducing radiation dose and hardware cost. The conventional wisdom is that the exact reconstruction of an interior ROI is very difficult to be obtained by only using data associated with lines through the ROI. In this study, we propose and investigate optimization-based methods for ROI and interior reconstructions based on total variation (TV) and data derivative...
April 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29728234/novel-light-guide-pmt-geometries-to-reduce-dead-edges-of-a-scintillation-camera
#14
Beien Wang, Rob Kreuger, Freek J Beekman, Marlies C Goorden
Anger cameras based on monolithic NaI scintillators read out by an array of PMTs are predominant in planar gamma imaging and SPECT. However, position estimation of gamma interactions is usually severely degraded near the edges of the scintillator which can be extremely undesirable for applications like breast imaging. Here we propose a relatively cost-effective solution based on the use of scintillators with absorptive edges with an unconventional light-guide-PMT layout employing a maximum likelihood positioning algorithm...
April 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29728233/multifunctional-chitosan-capped-gold-nanoparticles-for-enhanced-cancer-chemo-radiotherapy-an-invitro-study
#15
Mohamed Mahmoud Fathy, Fayrouz S Mohamed, NihalSaad Elbialy, Wael M Elshemey
Over the last decade, chemo-radiotherapy represented a well-established paradigm for cancer treatment. Developing new strategies to promote the therapeutic efficacy while reducing toxic side effects of chemo-radiotherapy is a main research objective in cancer therapy. A promising new oncological strategy for enhancing chemo-radiotherapy against cancer involves the utilization of multifunctional nanoparticles (nanocarriers and radiosensitizers). In this work, Chitosan-Capped Gold Nanoparticles (CS-GNPs) were synthesized and loaded with an anticancer agent, Doxorubicin (CS-GNPs-DOX)...
April 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29728232/monte-carlo-simulation-of-eye-lens-dose-reduction-from-ct-scan-using-organ-based-tube-current-modulation
#16
REVIEW
Ying Huang, Weihai Zhuo, Yiming Gao, Haikuan Liu
PURPOSE: To investigate lens dose reduction with organ based tube current modulation (TCM) using the Monte Carlo method. METHODS: To calculate lens dose with organ based TCM, 36 pairs of X-ray sources with bowtie filters were placed around the patient head using a projection angle interval of 10° for one rotation of Computed Tomography (CT). Each projection was simulated respectively. Both voxelized and stylized eye models and Chinese reference male phantoms were used in the simulation, and tube voltages 80, 100, 120 and 140 kVp were used...
April 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29728231/chirp-phantom-for-mtf-calculations-a-study-of-its-precision-in-noisy-environments
#17
Antonio González-López
Bar pattern phantoms are used to determine the maximum number of line-pairs per mm that an imaging system can resolve. In some cases, a numerical determination of the modulation transfer function (MTF) can also be carried out. However, calculations can only be performed in a relatively small number of frequencies because of the small number of bar groups in the phantom. In this work, a new bar pattern phantom has been simulated. This phantom consists of 66 pairs of lines of different periods and these periods vary exponentially with spatial position, like in a chirp wave...
April 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29728230/log-file-based-patient-dose-calculations-of-double-arc-vmat-for-head-and-neck-radiotherapy
#18
Yoshiyuki Katsuta, Noriyuki Kadoya, Yukio Fujita, Eiji Shimizu, Kazuhiro Majima, Haruo Matsushita, Ken Takeda, Keiichi Jingu
PURPOSE: The log file-based method cannot display dosimetric changes due to linac component miscalibration because of the insensitivity of log files to linac component miscalibration. The purpose of this study was to supply dosimetric changes in log file-based patient dose calculations for double-arc volumetric-modulated arc therapy (VMAT) in head-and-neck cases. METHODS AND MATERIALS: Fifteen head-and-neck cases participated in this study. For each case, treatment planning system (TPS) doses were produced by double-arc and single-arc VMAT...
April 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29728229/quality-controls-in-digital-mammography-protocol-of-the-efomp-mammo-working-group
#19
Gisella Gennaro, Simona Avramova-Cholakova, Andrea Azzalini, Maria Luisa Chapel, Margarita Chevalier, Olivera Ciraj, Hugo de Las Heras, Vesna Gershan, Bengt Hemdal, Elizabeth Keavey, Nico Lanconelli, Susanne Menhart, Màrio João Fartaria, Ana Pascoal, Kristin Pedersen, Stefano Rivetti, Veronica Rossetti, Friedrich Semturs, Peter Sharp, Alberto Torresin
This article aims to present the protocol on Quality Controls in Digital Mammography published online in 2015 by the European Federation of Organisations for Medical Physics (EFOMP) which was developed by a Task Force under the Mammo Working Group. The main objective of this protocol was to define a minimum set of easily implemented quality control tests on digital mammography systems that can be used to assure the performance of a system within a set and acceptable range. Detailed step-by-step instructions have been provided, limiting as much as possible any misinterpretations or variations by the person performing...
April 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29728228/detection-of-structural-abnormalities-of-cortical-and-subcortical-gray-matter-in-patients-with-mri-negative-refractory-epilepsy-using-neurite-orientation-dispersion-and-density-imaging
#20
Masoumeh Rostampour, Hassan Hashemi, Seyed Morteza Najibi, Mohammad Ali Oghabian
PURPOSE: NODDI (Neurite Orientation Dispersion and Density Imaging) and DTI (Diffusion tensor imaging) may be useful in identifying abnormal regions in patients with MRI-negative refractory epilepsy. The aim of this study was to determine whether NODDI and DTI maps including neurite density (ND), orientation dispersion index (ODI), mean diffusivity (MD) and fractional anisotropy (FA) can detect structural abnormalities in cortical and subcortical gray matter (GM) in these patients. The correlation between these parameters and clinical characteristics of the disease was also investigated...
April 2018: Physica Medica: PM
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