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Physica Medica: PM

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https://www.readbyqxmd.com/read/27923551/absorbed-dose-and-image-quality-of-varian-truebeam-cbct-compared-with-obi-cbct
#1
Daisuke Kawahara, Shuichi Ozawa, Takeo Nakashima, Tatsuhiko Suzuki, Masato Tsuneda, Sodai Tanaka, Yoshimi Ohno, Yuji Murakami, Yasushi Nagata
PURPOSE: Nowadays, patient positioning and target localization can be verified by using kilovolt cone beam computed tomography (kV-CBCT). There have been various studies on the absorbed doses and image qualities of different kV-CBCT systems. However, the Varian TrueBeam CBCT (TB CBCT) system has not been investigated so far. We assess the image quality and absorbed dose of TB CBCT through comparison with those of on-board imager (OBI) CBCT. METHODS: The image quality was evaluated using two phantoms...
December 3, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27919623/assessment-of-the-neutron-dose-field-around-a-biomedical-cyclotron-fluka-simulation-and-experimental-measurements
#2
Angelo Infantino, Gianfranco Cicoria, Giulia Lucconi, Davide Pancaldi, Sara Vichi, Federico Zagni, Domiziano Mostacci, Mario Marengo
In the planning of a new cyclotron facility, an accurate knowledge of the radiation field around the accelerator is fundamental for the design of shielding, the protection of workers, the general public and the environment. Monte Carlo simulations can be very useful in this process, and their use is constantly increasing. However, few data have been published so far as regards the proper validation of Monte Carlo simulation against experimental measurements, particularly in the energy range of biomedical cyclotrons...
December 2, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27916516/local-dose-enhancement-of-proton-therapy-by-ceramic-oxide-nanoparticles-investigated-with-geant4-simulations
#3
Sally McKinnon, Susanna Guatelli, Sebastien Incerti, Vladimir Ivanchenko, Konstantin Konstantinov, Stéphanie Corde, Michael Lerch, Moeava Tehei, Anatoly Rosenfeld
Nanoparticles (NPs) have been shown to enhance X-ray radiotherapy and proton therapy of cancer. The effectiveness of radiation damage is enhanced in the presence of high atomic number (high-Z) NPs due to increased production of low energy, higher linear energy transfer (LET) secondary electrons when NPs are selectively internalized by tumour cells. This work quantifies the local dose enhancement produced by the high-Z ceramic oxide NPs Ta2O5 and CeO2, in the target tumour, for the first time in proton therapy, by means of Geant4 simulations...
December 1, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27914781/incident-air-kerma-to-absorbed-organ-dose-conversion-factors-for-breast-and-lung-in-pa-thorax-radiography-the-effect-of-patient-thickness-and-radiation-quality
#4
A Kelaranta, P Toroi, P Vock
PURPOSE: Converting the measurable quantities to patient organ doses in projection radiography is usually based on a standard-sized patient model and a specific radiation quality, which are likely to differ from the real situation. Large inaccuracies can therefore be obtained in organ doses, because organ doses are dependent on the exposure parameters, exposure geometry and patient anatomy. In this study, the effect of radiation quality and patient thickness on the organ dose conversion factors were determined...
November 30, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27914780/a-monte-carlo-analysis-of-breast-screening-randomized-trials
#5
Luis I Zamora, Cristina Forastero, Damián Guirado, Antonio M Lallena
PURPOSE: To analyze breast screening randomized trials with a Monte Carlo simulation tool. METHODS: A simulation tool previously developed to simulate breast screening programmes was adapted for that purpose. The history of women participating in the trials was simulated, including a model for survival after local treatment of invasive cancers. Distributions of time gained due to screening detection against symptomatic detection and the overall screening sensitivity were used as inputs...
November 30, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27914779/what-do-radiation-oncologists-require-for-future-advancements-in-lung-sbrt
#6
REVIEW
Umberto Ricardi, Serena Badellino, Andrea Riccardo Filippi
Stereotactic Body Radiotherapy (SBRT) is a well established therapeutic option for patients affected with peripheral early stage non-small cell lung cancer (NSCLC), given the positive clinical evidence accumulated so far on its efficacy and safety. SBRT is regarded as the best choice for inoperable patients, and could also be offered as an alternative to surgery to selected operable patients. More recently, its use for lung metastases progressively increased, and SBRT is now regarded as a low toxic and highly effective local therapy for lung oligometastases from different primary tumors, especially colorectal cancer...
November 30, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27899269/pixe-study-on-the-effects-of-parathyroid-hormone-on-elemental-content-in-rat-bones
#7
M H Eisa, H Shen, W Jin, Abdulaziz S Alaamer, M A Al-Rajhi, Hajo Idriss
Parathyroid hormone (PTH) has attracted considerable interest as a bone anabolic agent. PTH plays a central role in regulating calcium phosphate metabolism and its increases in production in response to low serum calcium levels. A continuous hypersecretion of PTH, as occurs in primary hyperparathyroidism, leads to bone resorption. In this study, the effect of different doses of parathyroid hormone (PTH) on bone mineral content (BMC) in rats was investigated by particle-induced X-ray emission (PIXE). This study will help in investigating further the toxicity of extremely high doses of PTH on BMC...
November 26, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27894729/effect-of-diagnostic-cone-beam-computed-tomography-protocols-on-image-quality-patient-dose-and-lesion-detection
#8
Jijo Paul, Annamma Chacko, Paola Saccomandi, Thomas J Vogl, Nour-Eldin A Nour-Eldin
OBJECTIVE: To evaluate the effect of cone-beam computed tomography (CBCT) image acquisition protocols on image quality, lesion detection, delineation, and patient dose. METHODS: 100-patients and a CTDI phantom combined with an electron density phantom were examined using four different CBCT-image acquisition protocols during image-guided transarterial chemoembolization (TACE). Protocol-1 (time: 6s, tube rotation: 360°), protocol-2 (5s, 300°), protocol-3 (4s, 240°) and protocol-4 (3s, 180°) were used...
November 25, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27890569/multi-strip-silicon-sensors-for-beam-array-monitoring-in-micro-beam-radiation-therapy
#9
E Alagoz, E Brauer-Krisch, A Bravin, I Cornelius, P Fournier, T E Hansen, A Kok, M Lerch, E Monakhov, J Morse, N Pacifico, M Petasecca, M Povoli, H Requard, A D Rozenfeld, M Salome, H Sandaker, B Stugu
We present here the latest results from tests performed at the ESRF ID17 and ID21 beamlines for the characterization of novel beam monitors for Microbeam Radiation Therapy (MRT), which is currently being implemented at ID17. MRT aims at treating solid tumors by exploiting an array of evenly spaced microbeams, having an energy spectrum distributed between 27 and 600keV and peaking at 100keV. Given the high instantaneous dose delivered (up to 20kGy/s), the position and the intensity of the microbeams has to be precisely and instantly monitored...
November 24, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27890568/dose-calculation-algorithm-accuracy-for-small-fields-in-non-homogeneous-media-the-lung-sbrt-case
#10
REVIEW
Antonella Fogliata, Luca Cozzi
This review addresses the theme of dose calculation accuracy in the case of the stereotactic treatment of lung lesions. Based on the classical categories of type "a", "b" and "c" algorithms (according to their degree of complexity in the management of charged particle transport), a summary of findings from literature is reported. Two main critical areas have been identified: the use of small fields and the presence of low density medium. Concerning the latter point, the algorithm accuracy is intrinsic of the algorithm core, and, notwithstanding the materials discretization and their chemical composition knowledge, type "c" are, at the most, able to reproduce the actual physical dose distribution in heterogeneous media...
November 24, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27890567/commissioning-of-the-4-d-treatment-delivery-system-for-organ-motion-management-in-synchrotron-based-scanning-ion-beams
#11
Mario Ciocca, Alfredo Mirandola, Silvia Molinelli, Stefania Russo, Edoardo Mastella, Alessandro Vai, Andrea Mairani, Giuseppe Magro, Andrea Pella, Marco Donetti, Francesca Valvo, Piero Fossati, Guido Baroni
PURPOSE: The aim of this work was the commissioning of delivery procedures for the treatment of moving targets in scanning pencil beam hadrontherapy. METHODS: EBT3 films fixed to the Anzai Respiratory Phantom were exposed to carbon ion scanned homogeneous fields (E=332MeV/u). To evaluate the interplay effect, field size and flatness for 3 different scenarios were compared to static condition: gated irradiation or repainting alone and combination of both. Respiratory signal was provided by Anzai pressure sensor or optical tracking system (OTS)...
November 24, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27890566/management-of-interruptions-to-fractionated-radiotherapy-treatments-four-and-a-half-years-of-experience
#12
J M de la Vega, B Ríos, J Torres Del Río, R Guerrero, I Castillo, D Guirado
BACKGROUND AND PURPOSE: The study objective was to report our four-and-a half years experience (March 1 2011-August 15 2015) of a program to manage interruptions in fractionated radiotherapy treatments. METHODS: A program was developed, based on a specific database, to manage treatment interruptions. Benefits of the program were analyzed in reference to previously published data. Analysis was also performed of two measures to reduce OTT prolongation and improve treatment outcomes: working on public holidays and conducting treatment unit maintenance on Saturdays...
November 24, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27889131/development-of-monte-carlo-based-real-time-treatment-planning-system-with-fast-calculation-algorithm-for-boron-neutron-capture-therapy
#13
Kenta Takada, Hiroaki Kumada, Peng Hong Liem, Hideyuki Sakurai, Takeji Sakae
PURPOSE: We simulated the effect of patient displacement on organ doses in boron neutron capture therapy (BNCT). In addition, we developed a faster calculation algorithm (NCT high-speed) to simulate irradiation more efficiently. METHODS: We simulated dose evaluation for the standard irradiation position (reference position) using a head phantom. Cases were assumed where the patient body is shifted in lateral directions compared to the reference position, as well as in the direction away from the irradiation aperture...
November 23, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27889130/can-the-non-pre-whitening-model-observer-including-aspects-of-the-human-visual-system-predict-human-observer-performance-in-mammography
#14
R W Bouwman, R E van Engen, M J M Broeders, G J den Heeten, D R Dance, K C Young, W J H Veldkamp
PURPOSE: In mammography, images are processed prior to display. Current methodologies based on physical image quality measurements are however not designed for the evaluation of processed images. Model observers (MO) might be suitable for this evaluation. The aim of this study was to investigate whether the non-pre-whitening (NPW) MO can be used to predict human observer performance in mammography-like images by including different aspects of the human visual system (HVS). METHODS: The correlation between human and NPW MO performance has been investigated for the detection of disk shaped objects in simulated white noise (WN) and clustered lumpy backgrounds (CLB), representing quantum noise limited and mammography-like images respectively...
November 23, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27887983/method-of-evaluating-respiratory-induced-organ-motion-by-vector-volume-histogram
#15
Hideharu Miura, Shuichi Ozawa, Hideo Kawabata, Yoshiko Doi, Masahiro Kenjou, Kengo Furukawa, Minoru Nakao, Yasushi Nagata
PURPOSE: Published organ motion data have been collected from measurements of a limited number of points within the organ, the centroid, or the edge of the organ. These are derived from the spatial characteristics of respiratory induced motion; however, this approach does not consider non-rigid organ deformation. We propose a novel quantitative method for evaluating respiratory induced organ motion using Deformable Image Registration (DIR). METHOD: Two phases from a 4-dimensional computed tomography (4D CT) dataset at maximum inspiration and expiration were each taken from five patients...
November 22, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27884463/gated-carbon-ion-scanning-treatment-for-pancreatic-tumour-with-field-specific-target-volume-and-organs-at-risk
#16
Kentaro Miki, Shinichiro Mori, Miho Shiomi, Shigeru Yamada
OBJECTIVE: To assess the feasibility of treatment planning for pancreatic tumours subject to respiratory motion using field-specific target volumes (FTV) and field-specific organs at risk (FOAR) using four-dimensional computed tomography (4DCT). METHODS: Fourteen pancreatic cancer patients underwent 4DCT. Radiation oncologists contoured the gross tumour volume (GTV), clinical target volume (CTV), spinal cord, duodenum, kidneys, and stomach. The gating duty cycle was set to 30 % around exhalation...
November 21, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27881295/measuring-dose-from-radiotherapy-treatments-in-the-vicinity-of-a-cardiac-pacemaker
#17
Samuel C Peet, Rachael Wilks, Tanya Kairn, Scott B Crowe
This study investigated the dose absorbed by tissues surrounding artificial cardiac pacemakers during external beam radiotherapy procedures. The usefulness of out-of-field reference data, treatment planning systems, and skin dose measurements to estimate the dose in the vicinity of a pacemaker was also examined. Measurements were performed by installing a pacemaker onto an anthropomorphic phantom, and using radiochromic film and optically stimulated luminescence dosimeters to measure the dose in the vicinity of the device during the delivery of square fields and clinical treatment plans...
November 21, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27876537/artificial-neural-networks-approach-to-pharmacokinetic-model-selection-in-dce-mri-studies
#18
Mohammad-Reza Mohammadian-Behbahani, Ali-Reza Kamali-Asl
PURPOSE: In pharmacokinetic analysis of Dynamic Contrast Enhanced MRI data, a descriptive physiological model should be selected properly out of a set of candidate models. Classical techniques suggested for this purpose suffer from issues like computation time and general fitting problems. This article proposes an approach based on Artificial Neural Networks (ANNs) for solving these problems. METHODS: A set of three physiologically and mathematically nested models generated from the Tofts model were assumed: Model I, II and III...
November 19, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27876285/zero-field-pdd-and-tmr-data-for-unflattened-beams-in-conventional-linacs-a-tool-for-independent-dose-calculations
#19
Silvia Strolin, Silvia Minosse, Marco D'Andrea, Francesco Fracchiolla, Vicente Bruzzaniti, Stefano Luppino, Marcello Benassi, Lidia Strigari
PURPOSE: To investigate the applicability of the formalism described in BJR supplement n.25 for Flattening Filter Free (FFF) beams in determining the zero-field tissue maximum ratio (TMR) for an independent calculation method of Percentage Depth Doses (PDDs) and relative dose factors (RDFs) at different experimental setups. METHODS: Experimental PDDs for field size from 40×40cm(2) to 2×2cm(2) with Source Surface Distance (SSD) 100cm were acquired. The normalized peak scatter factor for each square field was obtained by fitting experimental RDFs in water and collimator factors (CFs) in air...
November 18, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27876284/calculation-of-tumour-and-normal-tissue-biological-effective-dose-in-90-y-liver-radioembolization-with-different-dosimetric-methods
#20
Elena Gallio, Elisa Richetta, Monica Finessi, Michele Stasi, Riccardo Emanuele Pellerito, Gianni Bisi, Roberto Ropolo
PURPOSE: Radioembolization with (90)Y microspheres is an effective treatment for unresectable liver tumours. Two types of microspheres are available: resin (SIR-Spheres®) and glass (Theraspheres®). The aim of this study is to compare biological effective dose (BED) values obtained with three different dosimetric methods. METHODS: 29 HCC patients were included in this study: 15 were treated with resin(mean injected activity 1.5GBq, range 0.8-2.7GBq) and 14 with glass microspheres (2...
November 18, 2016: Physica Medica: PM
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