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Physica Medica: PM

G Guidi, N Maffei, B Meduri, E D'Angelo, G M Mistretta, P Ceroni, A Ciarmatori, A Bernabei, S Maggi, M Cardinali, V E Morabito, F Rosica, S Malara, A Savini, G Orlandi, C D'Ugo, F Bunkheila, M Bono, S Lappi, C Blasi, F Lohr, T Costi
PURPOSE: To predict patients who would benefit from adaptive radiotherapy (ART) and re-planning intervention based on machine learning from anatomical and dosimetric variations in a retrospective dataset. MATERIALS AND METHODS: 90 patients (pts) treated for head-neck cancer (H&N) formed a multicenter data-set. 41 H&N pts (45.6%) were considered for learning; 49 pts (54.4%) were used to test the tool. A homemade machine-learning classifier was developed to analyze volume and dose variations of parotid glands (PG)...
October 17, 2016: Physica Medica: PM
Margherita Zani, Cinzia Talamonti, Marta Bucciolini, Marco Marinelli, Gianluca Verona-Rinati, Pierluigi Bonomo, Fabiola Paiar, Stefania Pallotta
PURPOSE: Aim of this work is the assessment of build-up and superficial doses of different clinical Head&Neck plans delivered with Helical TomoTherapy (HT) (Accuray, Sunnyvale, CA). Depth dose profiles and superficial dose points were measured in order to evaluate the Treatment Planning System (TPS) capability of an accurate dose modeling in regions of disequilibrium. Geometries and scattering conditions were investigated, similar to the ones generally encountered in clinical treatments...
October 15, 2016: Physica Medica: PM
Laure Vieillevigne, Sandra Bessieres, Monia Ouali, Christel Lanaspeze
PURPOSE: Flattening filter free (FFF) beams are frequently used for stereotactic body radiation therapy with various treatment modalities: conventional static fields, dynamic conformal arc (DCA) or Rapid Arc (RA). The goal of this study was to obtain some criteria to enable a conscious choice of the employment of FFF beams and of the DCA or RA technique, depending on the PTV size. METHODS AND MATERIALS: 24 PTVs from 1.52cm(3) to 445.24cm(3) were studied in various sites: virtual phantom, lung and liver...
October 15, 2016: Physica Medica: PM
Samuel J Blake, Zhangkai Cheng, Shaghik Atakaramians, Steven Meikle, Minghui Lu, Philip Vial, Zdenka Kuncic
PURPOSE: A Geant4 model of a novel, water-equivalent electronic portal imaging device (EPID) prototype for radiotherapy imaging and dosimetry utilising an array of plastic scintillating fibres (PSFs) has been developed. Monte Carlo (MC) simulations were performed to quantify the PSF-EPID imaging performance and to investigate design aspects affecting performance for optimisation. METHODS: Using the Geant4 model, the PSF-EPID's imaging performance for 6 MV photon beams was quantified in terms of its modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE)...
October 13, 2016: Physica Medica: PM
Lorenzo Massimi, Michela Fratini, Inna Bukreeva, Francesco Brun, Alberto Mittone, Gaetano Campi, Raffaele Spanò, Milena Mastrogiacomo, Nicole Kerlero de Rosbo, Alberto Bravin, Antonio Uccelli, Alessia Cedola
High resolution Synchrotron-based X-ray Phase Contrast Tomography (XPCT) allows the simultaneous detection of three dimensional neuronal and vascular networks without using contrast agents or invasive casting preparation. We show and discuss the different features observed in reconstructed XPCT volumes of the ex vivo mouse spinal cord in the lumbo-sacral region, including motor neurons and blood vessels. We report the application of an intensity-based segmentation method to detect and quantitatively characterize the modification in the vascular networks in terms of reduction in experimental visibility...
October 12, 2016: Physica Medica: PM
E C Simpson
PURPOSE: Positron emitting isotopes such as (11)C and (10)C can be used for vital dose verification in hadron therapy. These isotopes are produced when the high energy (12)C primary beam particles undergo nuclear reactions within the patient. METHODS: We discuss a model for calculating cross sections for the production (11)C in (12)C+(12)C collisions, applicable at hadron therapy energies. RESULTS: Good agreement with the available cross section measurements is found for (12)C(-1n), though more detailed, systematic measurements would be very valuable...
October 11, 2016: Physica Medica: PM
Seyed Amir Hossein Batouli, Nafiseh Hasani, Sara Gheisari, Ebrahim Behzad, Mohammad Ali Oghabian
Brain lesions cause functional deficits, and one treatment for this condition is lesion resection. In most cases, presurgical planning (PSP) and the information from laterality indices are necessary for maximum preservation of the critical functions after surgery. Language laterality index (LI) is reliably estimated using functional magnetic resonance imaging (fMRI); however, this measure is under the influence of some external factors. In this study, we investigated the influence of a number of factors on language LI, using data from 120 patients (mean age=35...
October 11, 2016: Physica Medica: PM
J J Bailey, A S Kadyrov, I B Abdurakhmanov, D V Fursa, I Bray
Stopping powers of H, He, H2, and H2O targets for antiprotons have been calculated using a convergent close-coupling method. For He and H2 targets electron-electron correlations are fully accounted for using a multiconfiguration approximation. Two-electron processes are included using an independent-event model. The water molecule is described using a neon-like structure model with a pseudo-spherical potential. Results are tabulated for the purpose of Monte Carlo simulations to model antiproton transport through matter for radiation therapy...
October 11, 2016: Physica Medica: PM
A Cicchetti, T Rancati, M Ebert, C Fiorino, F Palorini, A Kennedy, D J Joseph, J W Denham, V Vavassori, G Fellin, B Avuzzi, C Stucchi, R Valdagni
AIM: To investigate late gastrointestinal toxicity in a large pooled population of prostate cancer patients treated with radical radiotherapy. Normal tissue complication probability models were developed for late stool frequency and late rectal pain. METHODS AND MATERIALS: Population included 1336 patients, 3-year minimum follow-up, treated with 66-80Gy. Toxicity was scored with LENT-SOMA-scale. Two toxicity endpoints were considered: grade ⩾2 rectal pain and mean grade (average score during follow-up) in stool frequency >1...
October 6, 2016: Physica Medica: PM
V Peppa, E P Pappas, P Karaiskos, T Major, C Polgár, P Papagiannis
PURPOSE: To investigate the clinical significance of introducing model based dose calculation algorithms (MBDCAs) as an alternative to TG-43 in (192)Ir interstitial breast brachytherapy. MATERIALS AND METHODS: A 57 patient cohort was used in a retrospective comparison between TG-43 based dosimetry data exported from a treatment planning system and Monte Carlo (MC) dosimetry performed using MCNP v. 6.1 with plan and anatomy information in DICOM-RT format. Comparison was performed for the target, ipsilateral lung, heart, skin, breast and ribs, using dose distributions, dose-volume histograms (DVH) and plan quality indices clinically used for plan evaluation, as well as radiobiological parameters...
October 5, 2016: Physica Medica: PM
Sankar Arumugam, Aitang Xing, Tony Young, David Thwaites, Lois Holloway
AIM: To study the sensitivity of three commercial dosimetric systems, Delta4, Multicube and Octavius4D, in detecting Volumetric Modulated Arc Therapy (VMAT) delivery errors. METHODS: Fourteen prostate and head and neck (H&N) VMAT plans were considered for this study. Three types of errors were introduced into the original plans: gantry angle independent and dependent MLC errors, and gantry angle dependent dose errors. The dose matrix measured by each detector system for the no-error and error introduced delivery were compared with the reference Treatment Planning System (TPS) calculated dose matrix for no-error plans using gamma (γ) analysis with 2%/2mm tolerance criteria...
October 4, 2016: Physica Medica: PM
Arkadiusz Sitek, Quanzheng Li, Georges El Fakhri, Nathaniel M Alpert
INTRODUCTION: Kinetic compartmental analysis is frequently used to compute physiologically relevant quantitative values from time series of images. In this paper, a new approach based on Bayesian analysis to obtain information about these parameters is presented and validated. MATERIALS AND METHODS: The closed-form of the posterior distribution of kinetic parameters is derived with a hierarchical prior to model the standard deviation of normally distributed noise...
September 28, 2016: Physica Medica: PM
M D'Arienzo, M L Cozzella, A Fazio, P De Felice, G Iaccarino, M D'Andrea, S Ungania, M Cazzato, K Schmidt, S Kimiaei, L Strigari
Peptide receptor therapy with (177)Lu-labelled somatostatin analogues is a promising tool in the management of patients with inoperable or metastasized neuroendocrine tumours. The aim of this work was to perform accurate activity quantification of (177)Lu in complex anthropomorphic geometry using advanced correction algorithms. Acquisitions were performed on the higher (177)Lu photopeak (208keV) using a Philips IRIX gamma camera provided with medium-energy collimators. System calibration was performed using a 16mL Jaszczak sphere surrounded by non-radioactive water...
September 28, 2016: Physica Medica: PM
Dete van Eeden, Freek du Plessis
INTRODUCTION: A mathematical 3D model of an existing computed tomography (CT) scanner was created and used in the EGSnrc-based BEAMnrc and egs_cbct Monte Carlo codes. Simulated transmission dose profiles of a RMI-465 phantom were analysed to verify Hounsfield numbers against measured data obtained from the CT scanner. METHODS AND MATERIALS: The modelled CT unit is based on the design of a Toshiba Aquilion 16 LB CT scanner. As a first step, BEAMnrc simulated the X-ray tube, filters, and secondary collimation to obtain phase space data of the X-ray beam...
September 24, 2016: Physica Medica: PM
Sally McKinnon, Elette Engels, Moeava Tehei, Konstantin Konstantinov, Stéphanie Corde, Sianne Oktaria, Sebastien Incerti, Michael Lerch, Anatoly Rosenfeld, Susanna Guatelli
The application of nanoparticles (NPs) in radiotherapy is an increasingly attractive technique to improve clinical outcomes. The internalisation of NPs within the tumour cells enables an increased radiation dose to critical cellular structures. The purpose of this study is to investigate, by means of Geant4 simulations, the dose enhancement within a cell population irradiated with a 150kVp photon field in the presence of a varying concentration of tantalum pentoxide (Ta2O5) NP aggregates, experimentally observed to form shells within tumour cells...
September 22, 2016: Physica Medica: PM
Massimiliano Pacilio, Bartolomeo Cassano, Carlo Chiesa, Stefano Giancola, Mahila Ferrari, Cinzia Pettinato, Ernesto Amato, Federica Fioroni, Leda Lorenzon, Rosanna Pellegrini, Elisabetta Di Castro, Roberto Pani, Marta Cremonesi
PURPOSE: The aims of this work were to explore patient eligibility criteria for dosimetric studies in (223)Ra therapy and evaluate the effects of differences in gamma camera calibration procedures into activity quantification. METHODS: Calibrations with (223)Ra were performed with four gamma cameras (3/8-inch crystal) acquiring planar static images with double-peak (82 and 154keV, 20% wide) and MEGP collimator. The sensitivity was measured in air by varying activity, source-detector distance, and source diameter...
September 20, 2016: Physica Medica: PM
N Reynaert, B Demol, M Charoy, S Bouchoucha, F Crop, A Wagner, T Lacornerie, F Dubus, E Rault, P Comte, R Cayez, C Boydev, D Pasquier, X Mirabel, E Lartigau, T Sarrazin
PURPOSE: The main focus of the current paper is the clinical implementation of a Monte Carlo based platform for treatment plan validation for Tomotherapy and Cyberknife, without adding additional tasks to the dosimetry department. METHODS: The Monte Carlo platform consists of C++ classes for the actual functionality and a web based GUI that allows accessing the system using a web browser. Calculations are based on BEAMnrc/DOSXYZnrc and/or GATE and are performed automatically after exporting the dicom data from the treatment planning system...
September 19, 2016: Physica Medica: PM
S Incerti, M Douglass, S Penfold, S Guatelli, E Bezak
Emerging radiotherapy treatments including targeted particle therapy, hadron therapy or radiosensitisation of cells by high-Z nanoparticles demand the theoretical determination of radiation track structure at the nanoscale. This is essential in order to evaluate radiation damage at the cellular and DNA level. Since 2007, Geant4 offers physics models to describe particle interactions in liquid water at the nanometre level through the Geant4-DNA Package. This package currently provides a complete set of models describing the event-by-event electromagnetic interactions of particles with liquid water, as well as developments for the modelling of water radiolysis...
September 19, 2016: Physica Medica: PM
Salvatore Berenato, Ernesto Amato, Alexander Fischer, Sergio Baldari
Internal dosimetry is a fundamental instrument for the personalization of nuclear medicine therapies, to maximize the therapeutic effect while minimizing the radiation burden to other organs. Three-dimensional (3D) dosimetry can quantify the impact of heterogeneous radiopharmaceutical distributions in organs, lesions and tissues. We analysed the influence of radionuclide voxel S factors in 3D dosimetry of (111)In, (177)Lu and (90)Y, the most used radionuclides in Peptide Receptor Radionuclide Therapy (PRRT)...
September 19, 2016: Physica Medica: PM
Elisa Scalco, Simona Marzi, Giuseppe Sanguineti, Antonello Vidiri, Giovanna Rizzo
PURPOSE: In the treatment of Head-and-Neck Squamous Cell Carcinoma (HNSCC), the early prediction of residual malignant lymph nodes (LNs) is currently required. Here, we investigated the potential of a multi-modal characterization (combination of CT, T2w-MRI and DW-MRI) at baseline and at mid-treatment, based on texture analysis (TA), for the early prediction of LNs response to chemo-radiotherapy (CRT). METHODS: 30 patients with pathologically confirmed HNSCC treated with CRT were considered...
September 14, 2016: Physica Medica: PM
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