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Physica Medica: PM

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https://www.readbyqxmd.com/read/28739143/prediction-of-time-integrated-activity-coefficients-in-prrt-using-simulated-dynamic-pet-and-a-pharmacokinetic-model
#1
Deni Hardiansyah, Ali Asgar Attarwala, Peter Kletting, Felix M Mottaghy, Gerhard Glatting
PURPOSE: To investigate the accuracy of predicted time-integrated activity coefficients (TIACs) in peptide-receptor radionuclide therapy (PRRT) using simulated dynamic PET data and a physiologically based pharmacokinetic (PBPK) model. METHODS: PBPK parameters were estimated using biokinetic data of 15 patients after injection of (152±15)MBq of (111)In-DTPAOC (total peptide amount (5.78±0.25)nmol). True mathematical phantoms of patients (MPPs) were the PBPK model with the estimated parameters...
July 21, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28736285/optimization-of-gate-simulations-for-whole-body-planar-scintigraphic-acquisitions-using-the-xcat-male-phantom-with-177-lu-dotatate-biokinetics-in-a-siemens-symbia-t2
#2
G C A Costa, D A B Bonifácio, D Sarrut, T Cajgfinger, M Bardiès
Simulations of planar whole body acquisitions in therapeutic procedures are often extensively time-consuming and therefore rarely used. However, optimising tools and variance reduction techniques can be employed to overcome this problem. In this paper, a variety of features available in GATE are explored and their capabilities to reduce simulation time are evaluated. For this purpose, the male XCAT phantom was used as a virtual patient with (177)Lu-DOTATATE pharmacokinetic for whole body planar acquisition simulations in a Siemens Symbia T2 model...
July 20, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28736284/adam-a-breathing-phantom-for-lung-sbrt-quality-assurance
#3
Stefania Pallotta, Silvia Calusi, Leonardo Foggi, Riccardo Lisci, Laura Masi, Livia Marrazzo, Cinzia Talamonti, Lorenzo Livi, Gabriele Simontacchi
PURPOSE: Radiotherapy treatment of moving lesions is a challenging task in which different strategies can be used to adequately treat the tumor while sparing the surrounding tissue. The complexity of these strategies requires accurate and appropriate quality assurance tests. For this purpose, ADAM (Anthropomorphic Dynamic breAthing Model), a new phantom which simulates realistic patient breathing, was developed aiming to test the image quality and dose delivery in lung cancer treatments...
July 20, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28736283/multicellular-dosimetric-chain-for-molecular-radiotherapy-exemplified-with-dose-simulations-on-3d-cell-spheroids
#4
Vappu Reijonen, Liisa K Kanninen, Eero Hippeläinen, Yan-Ru Lou, Eero Salli, Alexey Sofiev, Melina Malinen, Timo Paasonen, Marjo Yliperttula, Antti Kuronen, Sauli Savolainen
PURPOSE: Absorbed radiation dose-response relationships are not clear in molecular radiotherapy (MRT). Here, we propose a voxel-based dose calculation system for multicellular dosimetry in MRT. We applied confocal microscope images of a spherical cell aggregate i.e. a spheroid, to examine the computation of dose distribution within a tissue from the distribution of radiopharmaceuticals. METHODS: A confocal microscope Z-stack of a human hepatocellular carcinoma HepG2 spheroid was segmented using a support-vector machine algorithm and a watershed function...
July 20, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28729133/hybrid-framework-for-feasible-modeling-of-an-edge-illumination-x-ray-phase-contrast-imaging-system-at-a-human-scale
#5
Bartłomiej Włodarczyk, Jakub Pietrzak
Here, we present a hybrid approach for simulating an edge illumination X-ray phase-contrast imaging (EIXPCi) set-up using graphics processor units (GPU) with a high degree of accuracy. In this study, the applicability of pixel, mesh and non-uniform rational B-splines (NURBS) objects to carry out realistic maps of X-ray phase-contrast distribution at a human scale is accounted for by using numerical anthropomorphic phantoms and a very fast and robust simulation framework which integrates total interaction probabilities along selected X-ray paths...
July 17, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28716543/a-novel-method-for-ct-dosimetry-with-a-suspended-phantom-setup
#6
Mariaconcetta Longo, Elisabetta Genovese, Chiara Orlandi, Salvatore Donatiello, Bartolomeo Cassano, Mauro Colajacomo, Andrea Magistrelli, Paolo Tomà, Vittorio Cannatà
PURPOSE: This work presents a method for estimating CT dosimetric indices with a prototype designed for suspending the phantom/ion chamber system fixed at the CT isocenter. The purpose of this study was to validate the proposed methodology, which can be used to provide a direct assessment of dosimetric indices in helical scans. METHODS: The method is based on a reference setup in which the measuring system for CT dosimetry is in a stationary configuration, i.e. not bound to the CT table, and on a mathematical formalism developed for the proposed reference system...
July 14, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28716542/on-the-lateral-dose-profile-of-4-he-beams-in-water
#7
A Embriaco, V E Bellinzona, A Fontana, A Rotondi
PURPOSE: We investigate the possibility to improve the accuracy of the lateral dose profile for (4)He beams with a novel approach, by extending an already validated model for proton beams to heavier ions. METHODS: The full Molière theory for the Coulomb multiple scattering is applied to the case of (4)He beams, with a complete separation of the electromagnetic and of the nuclear contributions in the calculation of the total dose. The latter is described with only three free parameters...
July 14, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28716541/development-and-validation-of-an-accurate-gate-model-for-neuropet-scanner
#8
Peyman Sheikhzadeh, Hamid Sabet, Hossein Ghadiri, Parham Geramifar, Hojjat Mahani, Pardis Ghafarian, Mohammad Reza Ay
NeuroPET is a cylindrical full ring mobile PET/CT scanner for brain imaging that was developed by Photo Diagnostic Systems, Inc. The scanner has 7 modules, each with 3×4 detector blocks. The detectors have two layers of scintillator arrays with a half pixel pitch offset to realize two levels of depth of interaction. In this study, we evaluated the NeuroPET scanner modeled in the GATE simulation tool and analyzed the acquired data to better understand the contribution of inter-detector scattering (IDS). The results show that the average difference between simulated and measured data for a point-like source is 2...
July 14, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28712717/radiobiological-evaluation-of-prostate-cancer-imrt-and-conformal-rt-plans-using-different-treatment-protocols
#9
Panayiotis Mavroidis, Georgios Komisopoulos, Courtney Buckey, Margarita Mavroeidi, Gregory P Swanson, Dimos Baltas, Nikos Papanikolaou, Sotirios Stathakis
The purpose of this study is to evaluate the clinical efficacy of both step-and-shoot IMRT and 3D-Conformal Radiation Therapy modalities (CRT) in treating prostate cancer using radiobiological measures. Another aim was to estimate the risks for developing secondary malignancies in bladder and rectum due to radiotherapy from the corresponding modalities. The treatment plans of ten prostate cancer patients were developed using IMRT and CRT. For the IMRT plans, two beam energies and two treatment protocols were used (the RTOG 0415 and a most restrictive one proposed by Fox Chase Cancer Center (FCCC))...
July 13, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28712716/differentiation-of-glioma-malignancy-grade-using-diffusion-mri
#10
Ivan I Maximov, Aram S Tonoyan, Igor N Pronin
Modern diffusion MR protocols allow one to acquire the multi-shell diffusion data with high diffusion weightings in a clinically feasible time. In the present work we assessed three diffusion approaches based on diffusion and kurtosis tensor imaging (DTI, DKI), and neurite orientation dispersion and density imaging (NODDI) as possible biomarkers for human brain glioma grade differentiation based on the one diffusion protocol. We used three diffusion weightings (so called b-values) equal to 0, 1000, and 2500s/mm(2) with 60 non-coplanar diffusion directions in the case of non-zero b-values...
July 13, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28712715/split-vmat-technique-to-control-the-expiratory-breath-hold-time-in-liver-stereotactic-body-radiation-therapy
#11
Yen Hwa Lin, Shuichi Ozawa, Hideharu Miura, Katsunori Yogo, Takeo Nakashima, Kentaro Miki, Shintaro Tsuda, Yusuke Ochi, Daisuke Kawahara, Tomoki Kimura, Akito Saito, Yasushi Nagata
PURPOSE: In this study, we demonstrate the feasibility of using split-arcs in volumetric modulated arc therapy (VMAT), tailored for expiratory breath-hold in stereotactic body radiation therapy (SBRT) for liver tumors. We compare it with three-dimensional conformal radiation therapy (3D-CRT) and continuous-VMAT, for ten randomly selected hepatocellular carcinoma cases. METHODS: Four coplanar and four non-coplanar beams were used for the 3D-CRT plans. A pair of partial arcs, chosen using a back-and-forth rotating motion, were used for the continuous-VMAT plans...
July 13, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28712714/spinning-slithole-collimation-for-high-sensitivity-small-animal-spect-design-and-assessment-using-gate-simulation
#12
Hojjat Mahani, Gholamreza Raisali, Alireza Kamali-Asl, Mohammad Reza Ay
PURPOSE: While traditional collimations are widely used in preclinical SPECT imaging, they usually suffer from possessing a low system sensitivity leading to noisy images. In this study, we are aiming at introducing a novel collimator, the slithole, offering a superior resolution-sensitivity tradeoff for small animal SPECT. METHODS: The collimator was designed for a molecular SPECT scanner, the HiReSPECT. The slithole is a knife-edge narrow long aperture extended across long-axis of the camera's head...
July 13, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28709862/1st-european-congress-of-medical-physics-september-1-4-2016-medical-physics-innovation-and-vision-within-europe-and-beyond
#13
EDITORIAL
Virginia Tsapaki, George C Kagadis, Marco Brambilla, Mario Ciocca, Catharine H Clark, Harry Delis, Giovanni Mettivier
Medical Physics is the scientific healthcare profession concerned with the application of the concepts and methods of physics in medicine. The European Federation of Organisations for Medical Physics (EFOMP) acts as the umbrella organization for European Medical Physics societies. Due to the rapid advancements in related scientific fields, medical physicists must have continuous education through workshops, training courses, conferences, and congresses during their professional life. The latest developments related to this increasingly significant medical speciality were presented during the 1st European Congress of Medical Physics 2016, held in Athens, September 1-4, 2016, organized by EFOMP, hosted by the Hellenic Association of Medical Physicists (HAMP), and summarized in the current volume...
July 11, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28705507/dosimetric-comparison-of-rapidplan-and-manually-optimized-plans-in-volumetric-modulated-arc-therapy-for-prostate-cancer
#14
Kazuki Kubo, Hajime Monzen, Kentaro Ishii, Mikoto Tamura, Ryu Kawamorita, Iori Sumida, Hirokazu Mizuno, Yasumasa Nishimura
PURPOSE: This study evaluated whether RapidPlan based plans (RP plans) created by a single optimization, are usable in volumetric modulated arc therapy (VMAT) for patients with prostate cancer. METHODS: We used 51 previously administered VMAT plans to train a RP model. Thirty RP plans were created by a single optimization without planner intervention during optimization. Differences between RP plans and clinical manual optimization (CMO) plans created by an experienced planner for the same patients were analyzed (Wilcoxon tests) in terms of homogeneity index (HI), conformation number (CN), D95%, and D2% to planning target volume (PTV), mean dose, V50Gy, V70Gy, V75Gy, and V78Gy to rectum and bladder, monitor unit (MU), and multi-leaf collimator (MLC) sequence complexity...
July 10, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28676259/introduction-of-external-magnetic-fields-in-entropic-moment-modelling-for-radiotherapy
#15
J Page, Ph Nicolaï, G Birindelli, J Caron, B Dubroca, G Kantor, V Tikhonchuk, J-L Feugeas
One of the big challenges of the emerging MRI-guided radiotherapy is the prediction of an external magnetic field effect on the deposited dose induced by a beam of charged particles. In this paper, we present the results of the implementation of the Lorentz force in the deterministic M1 model. The validation of our code is performed by comparisons with the Monte-Carlo code FLUKA. The relevant examples show a significant modification of the shape of dose deposition volume induced by the external magnetic field in presence of heterogeneities...
July 1, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28673482/high-performance-modelling-of-the-transport-of-energetic-particles-for-photon-radiotherapy
#16
Gabriele Birindelli, Jean-Luc Feugeas, Jérôme Caron, Bruno Dubroca, Guy Kantor, Jonathan Page, Teddy Pichard, Vladimir Tikhonchuk, Philippe Nicolaï
This work consists of the validation of a new Grid Based Boltzmann Solver (GBBS) conceived for the description of the transport and energy deposition by energetic particles for radiotherapy purposes. The entropic closure and a compact mathematical formulation allow our code (M1) to calculate the delivered dose with an accuracy comparable to the Monte-Carlo (MC) codes with a computational time that is reduced to the order of few minutes without any special processing power requirement. A validation protocol with heterogeneity inserts has been defined for different photon sources...
June 30, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28666767/towards-breast-cancer-rotational-radiotherapy-with-synchrotron-radiation
#17
Francesca Di Lillo, Giovanni Mettivier, Antonio Sarno, Roberta Castriconi, Paolo Russo
PURPOSE: We performed the first investigations, via measurements and Monte Carlo simulations on phantoms, of the feasibility of a new technique for synchrotron radiation rotational radiotherapy for breast cancer (SR(3)T). METHODS: A Monte Carlo (MC) code based on Geant4 toolkit was developed in order to simulate the irradiation with the SR(3)T technique and to evaluate the skin sparing effect in terms of centre-to-periphery dose ratio at different energies in the range 60-175keV...
June 27, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28662850/patient-dose-monitoring-systems-a-new-way-of-managing-patient-dose-and-quality-in-the-radiology-department
#18
N Fitousi
PURPOSE: Due to the upcoming European Directive (2013/59/EURATOM) and the increased focus on patient safety in international guidelines and regulations, Patient Dose Monitoring Systems, also called Dose Management Systems (DMS), are introduced in medical imaging departments. This article focusses on the requirements for a DMS, its benefits and the necessary implementation steps. METHOD: The implementation of a DMS can be perceived as a lengthy, yet worthy, procedure: users have to select the appropriate system for their applications, prepare data collection, validate, perform configuration, and start using the results in quality improvement projects...
June 26, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28662849/use-of-an-in-house-monte-carlo-platform-to-assess-the-clinical-impact-of-algorithm-related-dose-differences-on-dvh-constraints
#19
A Wagner, F Crop, X Mirabel, C Tailly, N Reynaert
PURPOSE: The aim of the present work is to evaluate a semi-automatic prescription and validation system of treatment plans for complex delivery techniques, integrated in a Monte Carlo platform, and to investigate the clinical impact of dose differences due to the calculation algorithms, by assessing the changes in DVH constraints. METHODS: A new prescription module was implemented into the Moderato system, an in-house Monte Carlo platform, with corresponding dose constraints generated depending on the anatomical region and fractionation scheme considered...
June 26, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28647449/igrt-and-motion-management-during-lung-sbrt-delivery
#20
REVIEW
Vincent Caillet, Jeremy T Booth, Paul Keall
Patient motion can cause misalignment of the tumour and toxicities to the healthy lung tissue during lung stereotactic body radiation therapy (SBRT). Any deviations from the reference setup can miss the target and have acute toxic effects on the patient with consequences onto its quality of life and survival outcomes. Correction for motion, either immediately prior to treatment or intra-treatment, can be realized with image-guided radiation therapy (IGRT) and motion management devices. The use of these techniques has demonstrated the feasibility of integrating complex technology with clinical linear accelerator to provide a higher standard of care for the patients and increase their quality of life...
June 21, 2017: Physica Medica: PM
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