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Physica Medica: PM

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https://www.readbyqxmd.com/read/28228330/assessment-of-monitor-unit-limiting-strategy-using-volumetric-modulated-arc-therapy-for-cancer-of-hypopharynx
#1
Shabbir Ahamed, Navin Singh, Deleep Gudipudi, Suneetha Mulinti, Anil Talluri, Bhudevi Soubhagya, Madhusudhana Sresty
PURPOSE: To quantify relative merit of MU deprived plans against freely optimized plans in terms of plan quality and report changes induced by progressive resolution optimizer algorithm (PRO3) to the dynamic parameters of RapidArc. MATERIALS AND METHODS: Ten cases of carcinoma hypopharynx were retrospectively planned in three phases without using MU tool. Replicas of these baseline plans were reoptimized using "Intermediate dose" feature and "MU tool" to reduce MUs by 20%, 35%, and 50%...
February 19, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28216331/development-of-a-four-dimensional-monte-carlo-dose-calculation-system-for-real-time-tumor-tracking-irradiation-with-a-gimbaled-x-ray-head
#2
Yoshitomo Ishihara, Mitsuhiro Nakamura, Yuki Miyabe, Nobutaka Mukumoto, Yukinori Matsuo, Akira Sawada, Masaki Kokubo, Takashi Mizowaki, Masahiro Hiraoka
PURPOSE: To develop a four-dimensional (4D) dose calculation system for real-time tumor tracking (RTTT) irradiation by the Vero4DRT. METHODS: First, a 6-MV photon beam delivered by the Vero4DRT was simulated using EGSnrc. A moving phantom position was directly measured by a laser displacement gauge. The pan and tilt angles, monitor units, and the indexing time indicating the phantom position were also extracted from a log file. Next, phase space data at any angle were created from both the log file and particle data under the dynamic multileaf collimator...
February 16, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28216330/-223-ra-dichloride-spectrometric-characterization-searching-for-the-presence-of-long-lived-isotopes-with-radiological-protection-implications
#3
J Sánchez-Jiménez, A López-Montes, L Núñez-Martínez, A Villa-Abaunza, L M Fraile, V Sánchez-Tembleque, J M Udías
(223)Ra-dichloride was approved with the commercial name of Xofigo in 2014 for treatment of metastatic castration-resistant prostate cancer. (223)Ra is obtained by neutron irradiation of (226)Ra yielding (227)Ac, which decays to (227)Th and (223)Fr, both decaying to (223)Ra. Since (223)Ra is predominantly (95.3%) an alpha emitter with a 11.42days long half-life, the radiopharmaceutical, its remnants, the patient, and waste material can be managed and disposed with low radiation protection requirements. (227)Ac is a long-lived (T1/2=21...
February 16, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28202324/polarity-and-ion-recombination-corrections-in-continuous-and-pulsed-beams-for-ionization-chambers-with-high-z-chamber-walls
#4
Ghada Aldosary, Habib Safigholi, William Song, Jan Seuntjens, Arman Sarfehnia
In this work, the response of Farmer-type ionization chambers fitted with high atomic number (Z) walls is studied, and results of the effects of such walls on polarity and ion recombination correction factors in both continuous and pulsed beams are presented. Measurements were made in a continuous Co-60 beam and a pulsed 6MV linac beam using an Exradin-A12 ionization chamber fitted with the manufacturer's C-552 plastic wall, as well as geometrically identical walls made from aluminum, copper and molybdenum...
February 12, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28189418/cancer-risk-after-radiotherapy-for-benign-diseases
#5
REVIEW
M Mazonakis, J Damilakis
Radiotherapy with low to intermediate doses has been historically employed for the management of several benign diseases. The exposure to ionizing radiation may increase the probability for carcinogenesis. The knowledge of this probability is of value for weighting the benefits and risks of radiotherapy against different therapeutic approaches. This study initially reviews the epidemiologic data associated with the cancer induction due to radiotherapy for non-malignant conditions in previous decades. Most of these data were derived from patients irradiated with conventional techniques, which are no longer applied, for some benign diseases not treated with radiotherapy nowadays...
February 8, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28188080/the-effect-of-18f-fdg-pet-image-reconstruction-algorithms-on-the-expression-of-characteristic-metabolic-brain-network-in-parkinson-s-disease
#6
Petra Tomše, Luka Jensterle, Sebastijan Rep, Marko Grmek, Katja Zaletel, David Eidelberg, Vijay Dhawan, Yilong Ma, Maja Trošt
PURPOSE: To evaluate the reproducibility of the expression of Parkinson's Disease Related Pattern (PDRP) across multiple sets of 18F-FDG-PET brain images reconstructed with different reconstruction algorithms. METHODS: 18F-FDG-PET brain imaging was performed in two independent cohorts of Parkinson's disease (PD) patients and normal controls (NC). Slovenian cohort (20 PD patients, 20 NC) was scanned with Siemens Biograph mCT camera and reconstructed using FBP, FBP+TOF, OSEM, OSEM+TOF, OSEM+PSF and OSEM+PSF+TOF...
February 7, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28173979/image-movement-of-the-elekta-epid-during-gantry-rotation-effects-on-the-verification-of-dose-distributions
#7
J Köhn, J Licher, M Mielke, B Loutfi-Krauss, N Blümer, B Heine, C Rödel, C Scherf, U Ramm
PURPOSE: The use of Electronic Portal Imaging Devices (EPIDs) to acquire dosimetric information, especially for 3D-back-projection, has been increasingly extended. For a precise back-projection, the accurate knowledge of the movement characteristics of the EPID during gantry rotation is an essential requirement. METHODS AND MATERIAL: Measurements were conducted with different alignments of steel balls, which were mounted on the treatment table to avoid secondary effects such as the mechanical sag of gantry or jaws...
February 4, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28148466/x-ray-dose-reduction-using-additional-copper-filtration-for-abdominal-digital-radiography-evaluation-using-signal-difference-to-noise-ratio
#8
Hiroki Kawashima, Katsuhiro Ichikawa, Daisuke Nagasou, Masayuki Hattori
PURPOSE: X-ray dose reduction using additional copper filters (Cu-filters) for abdominal general radiography was indicated in a report using a simulation study. We validated the dose reduction effects using a clinical digital radiography system equipped with an indirect-type CsI detector and an automatic Cu-filter insertion function. METHODS: The image qualities were evaluated using signal difference-to-noise ratio (SDNR) for different radiation qualities with and without Cu-filters for a 20-cm acrylic phantom...
January 29, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28139354/assessment-of-micronecrotic-tumor-tissue-using-dynamic-contrast-enhanced-magnetic-resonance-imaging
#9
Olga Schimpf, Stefan Hindel, Lutz Lüdemann
Compartmental models for evaluation of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) datasets assume a homogeneous interstitital volume distribution and homogeneous contrast agent (CA) distribution within each compartment, neglecting effects of CA diffusion within the compartments. When necrotic or micronecrotic tumor tissue is present, these assumptions may no longer be valid. Therefore, the present study investigates the validity of three compartmental models in assessing tumors with necrotic components...
January 27, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28131732/measurement-of-stray-neutron-doses-inside-the-treatment-room-from-a-proton-pencil-beam-scanning-system
#10
N Mojżeszek, J Farah, M Kłodowska, O Ploc, L Stolarczyk, M P R Waligórski, P Olko
PURPOSE: To measure the environmental doses from stray neutrons in the vicinity of a solid slab phantom as a function of beam energy, field size and modulation width, using the proton pencil beam scanning (PBS) technique. METHOD: Measurements were carried out using two extended range WENDI-II rem-counters and three tissue equivalent proportional counters. Detectors were suitably placed at different distances around the RW3 slab phantom. Beam irradiation parameters were varied to cover the clinical ranges of proton beam energies (100-220MeV), field sizes ((2×2)-(20×20)cm(2)) and modulation widths (0-15cm)...
January 25, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28131731/spectroscopic-study-of-prompt-gamma-emission-for-range-verification-in-proton-therapy
#11
Laurent Kelleter, Aleksandra Wrońska, Judith Besuglow, Adam Konefał, Karim Laihem, Johannes Leidner, Andrzej Magiera, Katia Parodi, Katarzyna Rusiecka, Achim Stahl, Thomas Tessonnier
We present the results of an investigation of the prompt-gamma emission from an interaction of a proton beam with phantom materials. Measurements were conducted with a novel setup allowing the precise selection of the investigated depth in the phantom, featuring three different materials composed of carbon, oxygen and hydrogen. We studied two beam energies of 70.54 and 130.87MeV and two detection angles: 90° and 120°. The results are presented in form of profiles of the prompt-gamma yield as a function of depth...
January 25, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28130055/optimal-dose-and-fraction-number-in-sbrt-of-lung-tumours-a-radiobiological-analysis
#12
Ruggero Ruggieri, Pavel Stavrev, Stefania Naccarato, Nadejda Stavreva, Filippo Alongi, Alan E Nahum
The efficacy of Stereotactic Body Radiation Therapy (SBRT) in early-stage non-small cell lung cancer for severely hypofractionated schedules is clinically proven. Tumour control probability (TCP) modelling might further optimize prescription dose and number of treatment fractions (n). To this end, we will discuss the following controversial questions. Which is the most plausible cell-survival model at doses per fraction (d) as high as 20Gy? Do clinical data support a dose-response relationship with saturation over some threshold-dose? Given the reduced re-oxygenation for severe hypofractionation, is the inclusion of tumour hypoxia in TCP modelling relevant? Can iso-effective schedules be derived by assuming a homogeneous tumour-cell population with α/β≈10Gy, or should distinct cell subpopulations, with different α/β values, be taken into account? Is there scope for patient-specific individualization of n? Despite the difficulty of providing definite answers to the above questions, reasonable suggestions for lung SBRT can be derived from the literature...
January 24, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28118950/characterization-of-a-commercial-scintillation-detector-for-2-d-dosimetry-in-scanned-proton-and-carbon-ion-beams
#13
S Russo, A Mirandola, S Molinelli, E Mastella, A Vai, G Magro, A Mairani, D Boi, M Donetti, M Ciocca
INTRODUCTION: Pencil beam scanning technique used at CNAO requires beam characteristics to be carefully assessed and periodically checked to guarantee patient safety. This study aimed at characterizing the Lynx® detector (IBA Dosimetry) for commissioning and periodic quality assurance (QA) for proton and carbon ion beams, as compared to EBT3 films, currently used for QA checks. METHODS AND MATERIALS: The Lynx® is a 2-D high-resolution dosimetry system consisting of a scintillating screen coupled with a CCD camera, in a compact light-tight box...
January 22, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28118951/brachyview-combining-ldr-seed-positions-with-transrectal-ultrasound-imaging-in-a-prostate-gel-phantom
#14
S Alnaghy, D L Cutajar, J A Bucci, K Enari, M Safavi-Naeini, M Favoino, M Tartaglia, F Carriero, J Jakubek, S Pospisil, M Lerch, A B Rosenfeld, M Petasecca
PURPOSE: BrachyView is a novel in-body imaging system which aims to provide LDR brachytherapy seeds position reconstruction within the prostate in real-time. The first prototype is presented in this study: the probe consists of a gamma camera featuring three single cone pinhole collimators embedded in a tungsten tube, above three, high resolution pixelated detectors (Timepix). METHODS: The prostate was imaged with a TRUS system using a sagittal crystal with a 2...
January 21, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28111101/design-of-a-new-tracking-device-for-on-line-beam-range-monitor-in-carbon-therapy
#15
Giacomo Traini, Giuseppe Battistoni, Angela Bollella, Francesco Collamati, Erika De Lucia, Riccardo Faccini, Fernando Ferroni, Paola Maria Frallicciardi, Carlo Mancini-Terracciano, Michela Marafini, Ilaria Mattei, Federico Miraglia, Silvia Muraro, Riccardo Paramatti, Luca Piersanti, Davide Pinci, Antoni Rucinski, Andrea Russomando, Alessio Sarti, Adalberto Sciubba, Martina Senzacqua, Elena Solfaroli-Camillocci, Marco Toppi, Cecilia Voena, Vincenzo Patera
Charged particle therapy is a technique for cancer treatment that exploits hadron beams, mostly protons and carbon ions. A critical issue is the monitoring of the beam range so to check the correct dose deposition to the tumor and surrounding tissues. The design of a new tracking device for beam range real-time monitoring in pencil beam carbon ion therapy is presented. The proposed device tracks secondary charged particles produced by beam interactions in the patient tissue and exploits the correlation of the charged particle emission profile with the spatial dose deposition and the Bragg peak position...
January 19, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28109567/evaluation-of-residual-abdominal-tumour-motion-in-carbon-ion-gated-treatments-through-respiratory-motion-modelling
#16
Giorgia Meschini, Matteo Seregni, Andrea Pella, Mario Ciocca, Piero Fossati, Francesca Valvo, Marco Riboldi, Guido Baroni
At the Italian National Centre for Oncologic Hadrontherapy (CNAO) patients with upper-abdominal tumours are being treated with carbon ion therapy, adopting the respiratory gating technique in combination with layered rescanning and abdominal compression to mitigate organ motion. Since online imaging of the irradiated volume is not feasible, this study proposes a modelling approach for the estimation of residual motion of the target within the gating window. The model extracts a priori respiratory motion information from the planning 4DCT using deformable image registration (DIR), then combines such information with the external surrogate signal recorded during dose delivery...
January 18, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28108100/three-dimensional-quality-assurance-of-imrt-prostate-plans-using-gel-dosimetry
#17
M A Silveira, J F Pavoni, O Baffa
Intensity modulated radiotherapy (IMRT) is one of the most modern radiation therapy treatment techniques. Although IMRT can deliver high and complex conformational doses to the tumor volume, its implementation requires rigorous quality assurance (QA) procedures that include a dosimetric pre-treatment verification of individual patient planning. This verification usually involves measuring a small volume of absolute dose with an ionization chamber and checking bi-dimensional fluency with an array of detectors...
January 17, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/27914779/what-do-radiation-oncologists-require-for-future-advancements-in-lung-sbrt
#18
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/28111100/monte-carlo-simulations-for-medical-physics-from-fundamental-physics-to-cancer-treatment
#19
EDITORIAL
S Guatelli, S Incerti
No abstract text is available yet for this article.
January 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28110824/clinical-significance-of-treatment-delivery-errors-for-helical-tomotherapy-nasopharyngeal-plans-a-dosimetric-simulation-study
#20
Shrikant Deshpande, Mark Geurts, Philip Vial, Peter Metcalfe, Mark Lee, Lois Holloway
PURPOSE: Develop a framework to characterize helical TomoTherapy (HT) machine delivery errors and their clinical significance. METHOD AND MATERIALS: Ten nasopharynx HT plans were edited to introduce errors in Jaw width (JW), couch speed (CS), gantry period (GP), gantry start position (GSP), multi leaf collimator leaf open times (MLC LOT). In case of MLC LOT only, both systematic and random delivery errors were investigated. Each error type was simulated independently for a range of magnitudes...
January 2017: Physica Medica: PM
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