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Drosoula Giantsoudi, Bruno De Man, Joost Verburg, Alexei Trofimov, Yannan Jin, Ge Wang, Lars Gjesteby, Harald Paganetti
A significant and increasing number of patients receiving radiation therapy present with metal objects close to, or even within, the treatment area, resulting in artifacts in computed tomography (CT) imaging, which is the most commonly used imaging method for treatment planning in radiation therapy. In the presence of metal implants, such as dental fillings in treatment of head-and-neck tumors, spinal stabilization implants in spinal or paraspinal treatment or hip replacements in prostate cancer treatments, the extreme photon absorption by the metal object leads to prominent image artifacts...
March 21, 2017: Physics in Medicine and Biology
Zhen Tian, Yongbao Li, Nima Hassan-Rezaeian, Steve B Jiang, Xun Jia
We have previously developed a GPU-based Monte Carlo (MC) dose engine on the OpenCL platform, named goMC, with a built-in analytical linear accelerator (linac) beam model. In this paper, we report our recent improvement on goMC to move it toward clinical use. First, we have adapted a previously developed automatic beam commissioning approach to our beam model. The commissioning was conducted through an optimization process, minimizing the discrepancies between calculated dose and measurement. We successfully commissioned six beam models built for Varian TrueBeam linac photon beams, including four beams of different energies (6 MV, 10 MV, 15 MV, and 18 MV) and two flattening-filter-free (FFF) beams of 6 MV and 10 MV...
March 2017: Journal of Applied Clinical Medical Physics
Tara Mastren, Valery Radchenko, Hong T Bach, Ethan R Balkin, Eva R Birnbaum, Mark Brugh, Jonathan W Engle, Matthew D Gott, James Guthrie, Heather M Hennkens, Kevin D John, Alan R Ketring, Marina Kuchuk, Joel R Maassen, Cleo M Naranjo, F Meiring Nortier, Tim E Phelps, Silvia S Jurisson, D Scott Wilbur, Michael E Fassbender
INTRODUCTION: Rhenium-186g (t1/2 = 3.72 d) is a β(-) emitting isotope suitable for theranostic applications. Current production methods rely on reactor production by way of the reaction (185)Re(n,γ)(186g)Re, which results in low specific activities limiting its use for cancer therapy. Production via charged particle activation of enriched (186)W results in a (186g)Re product with a higher specific activity, allowing it to be used more broadly for targeted radiotherapy applications. This targets the unmet clinical need for more efficient radiotherapeutics...
March 3, 2017: Nuclear Medicine and Biology
Marc Robini, Yuemin Zhu, Wanyu Liu, Isabelle Magnin
In spot-scanning particle therapy, inverse treatment planning is usually limited to finding the optimal beam fluences given the beam trajectories and energies. We address the much more challenging problem of jointly optimizing the beam fluences, trajectories and energies. For this purpose, we design a simulated annealing algorithm with an exploration mechanism that balances the conflicting demands of a small mixing time at high temperatures and a reasonable acceptance rate at low temperatures. Numerical experiments substantiate the relevance of our approach and open new horizons to spot-scanning particle therapy...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
S Rahmanian, M Niklas, A Abdollahi, O Jäkel, S Greilich
Ion beams radiotherapy with charged particles show greater relative biological effectiveness (RBE) compared to conventional photon therapy. This enhanced RBE is due to a localized energy deposition pattern, which is subject to large fluctuations on cellular scales. Fluorescent nuclear track detectors (FNTDs) based on Al2O3:C,Mg crystals coated with cells (Cell-Fit-HD) can provide information on individual cellular energy deposition. In this study we provide a theoretical framework to obtain the distribution of microscopic energy deposition and ionization density in cells exposed to ion beams and identifies contributions of five different sources of variations to the overall energy fluctuation at different depths of a biologically optimized spread-out Bragg peak...
April 7, 2017: Physics in Medicine and Biology
Giuseppe Magro, Tordis Dahle, Silvia Molinelli, Mario Ciocca, Piero Fossati, Alfredo Ferrari, Taku Inaniwa, Naruhiro Matsufuji, Kristian Ytre-Hauge, Andrea Mairani
Particle therapy facilities often require Monte Carlo (MC) simulations to overcome intrinsic limitations of analytical treatment planning systems (TPS) related to the description of the mixed radiation field and beam interaction with tissue inhomogeneities. Some of these uncertainties may affect the computation of effective dose distributions; therefore, particle therapy dedicated MC codes should provide both absorbed and biological doses. Two biophysical models are currently applied clinically in particle therapy: the Local Effect Model (LEM) and the Microdosimetric Kinetic Model (MKM)...
March 2, 2017: Physics in Medicine and Biology
Antonetta C Houweling, Koen Crama, Jorrit Visser, Kyohei Fukata, Coen R N Rasch, Tatsuya Ohno, Arjan Bel, Astrid van der Horst
Radiotherapy using charged particles is characterized by a low dose to the surrounding healthy organs, while delivering a high dose to the tumor. However, interfractional anatomical changes can greatly affect the robustness of particle therapy. Therefore, we compared the dosimetric impact of interfractional anatomical changes (i.e. body contour differences and gastrointestinal gas volume changes) in photon, proton and carbon ion therapy for pancreatic cancer patients. In this retrospective planning study, photon, proton and carbon ion treatment plans were created for 9 patients...
March 2, 2017: Physics in Medicine and Biology
Nicola Alessio, Giuseppe Esposito, Giovanni Galano, Roberto De Rosa, Pasquale Anello, Gianfranco Peluso, Maria Antonella Tabocchini, Umberto Galderisi
The use of high-linear energy transfer charged particles is gaining attention as a medical tool because of the emission of radiations with an efficient cell-killing ability. Considerable interest has developed in the use of targeted alpha-particle therapy for the treatment of micrometastases. Moreover, the use of helium beams is gaining momentum, especially for treating pediatric tumors. We analyzed the effects of alpha particles on bone marrow mesenchymal stromal cells (MSCs), which have a subpopulation of stem cells capable of generating adipocytes, chondrocytes, and osteocytes...
March 2, 2017: Journal of Cellular Biochemistry
Gianluca Memoli, Mihai Caleap, Michihiro Asakawa, Deepak R Sahoo, Bruce W Drinkwater, Sriram Subramanian
Controlling acoustic fields is crucial in diverse applications such as loudspeaker design, ultrasound imaging and therapy or acoustic particle manipulation. The current approaches use fixed lenses or expensive phased arrays. Here, using a process of analogue-to-digital conversion and wavelet decomposition, we develop the notion of quantal meta-surfaces. The quanta here are small, pre-manufactured three-dimensional units-which we call metamaterial bricks-each encoding a specific phase delay. These bricks can be assembled into meta-surfaces to generate any diffraction-limited acoustic field...
February 27, 2017: Nature Communications
Marco Schwarz, Giovanni Mauro Cattaneo, Livia Marrazzo
The application of high precision hypofractionated regimes (a.k.a. stereotactic body radiotherapy (SBRT)) to the treatment of lung cancer is a 'success story' of radiotherapy. From the technical perspective, lung SBRT is a challenging technique as all aspects of the treatment workflow, from imaging to dose calculation to treatment delivery, should be carefully handled in order to ensure consistency between planned and delivered dose. In this review such technical aspects are presented and discussed, looking at what has been developed over the years...
February 23, 2017: Physica Medica: PM
Wilfredo González, Cécile Peucelle, Yolanda Prezado
PURPOSE: Charged particles have several advantages over x-rays radiations, both in terms of physics and radiobiology. The combination of these advantages with those of minibeam radiation therapy (MBRT) could help enhancing the therapeutic index for some cancers with poor prognosis. Among the different ions explored for therapy, carbon ions are considered to provide the optimum physical and biological characteristics. Oxygen could be advantageous due to a reduced oxygen enhancement ratio along with a still moderate biological entrance dose...
February 25, 2017: Medical Physics
Panagiotis Papadimitroulas
PURPOSE: Monte Carlo (MC) simulations are a well-established method for studying physical processes in medical physics. The purpose of this review is to present GATE dosimetry applications on diagnostic and therapeutic simulated protocols. There is a significant need for accurate quantification of the absorbed dose in several specific applications such as preclinical and pediatric studies. METHODS: GATE is an open-source MC toolkit for simulating imaging, radiotherapy (RT) and dosimetry applications in a user-friendly environment, which is well validated and widely accepted by the scientific community...
February 21, 2017: Physica Medica: PM
Marc Robini, Yuemin Zhu, Wanyu Liu, Isabelle Magnin, Marc Robini, Yuemin Zhu, Wanyu Liu, Isabelle Magnin, Wanyu Liu, Yuemin Zhu, Marc Robini, Isabelle Magnin
In spot-scanning particle therapy, inverse treatment planning is usually limited to finding the optimal beam fluences given the beam trajectories and energies. We address the much more challenging problem of jointly optimizing the beam fluences, trajectories and energies. For this purpose, we design a simulated annealing algorithm with an exploration mechanism that balances the conflicting demands of a small mixing time at high temperatures and a reasonable acceptance rate at low temperatures. Numerical experiments substantiate the relevance of our approach and open new horizons to spot-scanning particle therapy...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Kavitaa Nedunchezhian, Nalini Aswath, Manigandan Thiruppathy, Sarumathi Thirugnanamurthy
Boron Neutron Capture Therapy (BNCT) is a radiation science which is emerging as a hopeful tool in treating cancer, by selectively concentrating boron compounds in tumour cells and then subjecting the tumour cells to epithermal neutron beam radiation. BNCT bestows upon the nuclear reaction that occurs when Boron-10, a stable isotope, is irradiated with low-energy thermal neutrons to yield α particles (Helium-4) and recoiling lithium-7 nuclei. A large number of 10 Boron (10B) atoms have to be localized on or within neoplastic cells for BNCT to be effective, and an adequate number of thermal neutrons have to be absorbed by the 10B atoms to maintain a lethal 10B (n, α) lithium-7 reaction...
December 2016: Journal of Clinical and Diagnostic Research: JCDR
Mindy Hsieh, Yingzi Liu, Farshad Mostafaei, Jean M Poulson, Linda H Nie
PURPOSE: Boron neutron capture therapy (BNCT) is a binary treatment modality that uses high LET particles to achieve tumor cell killing. Deuterium-deuterium (DD) compact neutron generators have advantages over nuclear reactors and large accelerators as the BNCT neutron source, such as their compact size, low cost, and relatively easy installation. The purpose of this study is to design a beam shaping assembly (BSA) for a DD neutron generator and assess the potential of a DD-based BNCT system using Monte Carlo (MC) simulations...
February 2017: Medical Physics
Nicolas Arbor, Stephane Higueret, Halima Elazhar, Rodolphe Combe, Philippe Meyer, Nicolas Dehaynin, Florence Taupin, Daniel Husson
The peripheral dose distribution is a growing concern for the improvement of new external radiation modalities. Secondary particles, especially photo-neutrons produced by the accelerator, irradiate the patient more than tens of centimeters away from the tumor volume. However the out-of-field dose is still not estimated accurately by the treatment planning softwares. This study demonstrates the possibility of using a specially designed CMOS sensor for fast and thermal neutron monitoring in radiotherapy. The 14 microns-thick sensitive layer and the integrated electronic chain of the CMOS are particularly suitable for real-time measurements in γ/n mixed fields...
March 7, 2017: Physics in Medicine and Biology
Yongqiang Li, Wen C Hsi
To analyze measurement deviations of patient-specific quality assurance (QA) using intensity-modulated spot-scanning particle beams, a commercial radiation dosimeter using 24 pinpoint ionization chambers was utilized. Before the clinical trial, validations of the radiation dosimeter and treatment planning system were conducted. During the clinical trial 165 measurements were performed on 36 enrolled patients. Two or three fields of particle beam were used for each patient. Measurements were typically performed with the dosimeter placed at special regions of dose distribution along depth and lateral profiles...
April 7, 2017: Physics in Medicine and Biology
Mitsutaka Yamaguchi, Yuto Nagao, Takahiro Satoh, Hiroyuki Sugai, Makoto Sakai, Kazuo Arakawa, Naoki Kawachi
The purpose of this study is to determine whether the main component of the low-energy (63-68 keV) particles emitted perpendicularly to the (12)C beam from the (12)C-irradiated region in a water phantom is secondary electron bremsstrahlung (SEB). Monte Carlo simulations of a (12)C-beam (290 MeV/u) irradiated on a water phantom were performed. A detector was placed beside the water phantom with a lead collimator between the phantom and the detector. To move the Bragg-peak position, a binary filter was placed in an upper stream of the phantom...
January 2017: Review of Scientific Instruments
Toke Printz Ringbæk, Yuri Simeonov, Matthias Witt, Rita Engenhart-Cabillic, Gerhard Kraft, Klemens Zink, Uli Weber
Porous materials with microscopic structures like foam, sponges, lung tissues and lung substitute materials have particular characteristics, which differ from those of solid materials. Ion beams passing through porous materials show much stronger energy straggling than expected for non-porous solid materials of the same thickness. This effect depends on the microscopic fine structure, the density and the thickness of the porous material. The beam-modulating effect from a porous plate enlarges the Bragg peak, yielding similar benefits in irradiation time reduction as a ripple filter...
April 7, 2017: Physics in Medicine and Biology
Nan Qin, Marco Pinto, Zhen Tian, Georgios Dedes, Arnold Pompos, Steve Jiang, Katia Parodi, Xun Jia
Monte Carlo (MC) simulation is considered as the most accurate method for calculation of absorbed dose and fundamental physics quantities related to biological effects in carbon ion therapy. To improve its computational efficiency, we have developed a GPU-oriented fast MC package named goCMC, for carbon therapy. goCMC simulates particle transport in voxelized geometry with kinetic energy up to 450 MeV/u. Class II condensed history simulation scheme with a continuous slowing down approximation was employed. Energy straggling and multiple scattering were modeled...
January 31, 2017: Physics in Medicine and Biology
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