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Physica Medica: PM

B Jones, J W Hopewell
Re-treatment, using megavoltage photon radiotherapy, can benefit carefully selected patients with new or recurrent tumours. Such re-treatments may involve the further exposure of tissues such as the brain or spinal cord. A time-dependent model has been developed, which incorporates data from all published radiobiological experiments concerned with the in vivo re-irradiation of the spinal cord using photons. It allows an estimation of the increasing recovery in tissue tolerance with elapsed time after the initial treatment course...
April 13, 2019: Physica Medica: PM
A Vamvakas, S Williams, K Theodorou, E Kapsalaki, K Fountas, C Kappas, K Vassiou, I Tsougos
AIMS AND OBJECTIVES: To investigate the value of advanced multiparametric MR imaging biomarker analysis based on radiomic features and machine learning classification, in the non-invasive evaluation of tumor heterogeneity towards the differentiation of Low Grade vs. High Grade Gliomas. METHODS AND MATERIALS: Forty histologically confirmed glioma patients (20 LGG and 20 HGG) who underwent a standard 3T-MRI tumor protocol with conventional (T1 pre/post-contrast, T2-FSE, T2-FLAIR) and advanced techniques (Diffusion Tensor and Perfusion Imaging, 1H-MR Spectroscopy), were included...
March 22, 2019: Physica Medica: PM
Camilla Scabbio, Simona Malaspina, Antonella Capozza, Claudio Selvaggi, Roberta Matheoud, Angelo Del Sole, Michela Lecchi
PURPOSE: We have recently demonstrated that iterative reconstruction algorithms with resolution recovery require the adoption of specific normal databases (NDBs) for perfusion SPECT quantification. This work was aimed at investigating the impact of patient low-dose imaging on NDBs and percent summed rest (SR%) and stress (SS%) scores. METHODS: Assuming that count statistics of shorter acquisition time may simulate that of lower patient dose, three simultaneous scans were acquired (BrightView, Philips) with different acquisition-time/projection: 30, 15 and 8 s (from 100% to 25% of the reference)...
March 16, 2019: Physica Medica: PM
Tom Sanderson, James Solomon, Chris Nottage, John Dickson
PURPOSE: A PET/CT scan of a uniformly filled 68 Ga phantom resulted in an unexpectedly low SUVmean of 0.88. A potential contributing cause of underestimation of 68 Ga SUV is overestimation of 68 Ga activity in the Radionuclide Calibrator associated with the PET/CT scanner. To investigate this, a Radionuclide Calibrator cross-calibration exercise was performed. METHODS: A source of 68 Ga was measured in 5 Capintec CRC-55tR calibrators using the pre-set 68 Ga calibrator factor of 416, and a Veenstra VDC-505 calibrator using a factor recommended by the manufacturer...
March 11, 2019: Physica Medica: PM
Cihan Göksu, Klaus Scheffler, Hartwig R Siebner, Axel Thielscher, Lars G Hanson
PURPOSE: MR Current Density Imaging (MRCDI) involves weak current-injection into the head. The resulting magnetic field changes are measured by MRI. Stray fields pose major challenges since these can dominate the fields caused by tissue currents. We analyze the sources and influences of stray fields. METHODS: First, we supply validation data for a recently introduced MRCDI method with an unprecedented noise floor of ∼0.1 nT in vivo. Second, we assess the accuracy limit of the method and our corresponding cable current correction in phantoms ensuring high signal-to-noise ratio (SNR)...
March 7, 2019: Physica Medica: PM
Anna Romanyukha, Mauro Carrara, Davide Mazzeo, Chiara Tenconi, Tebarak Al-Salmani, Joel Poder, Dean Cutajar, Iolanda Fuduli, Marco Petasecca, Joseph Bucci, Annamaria Cerrotta, Brigida Pappalardi, Federica Piccolo, Emanuele Pignoli, Anatoly Rosenfeld
The multichannel vaginal cylinder (MVC) applicator employed for gynecological high dose rate (HDR) brachytherapy increases dose delivery complexity, and thus makes the treatment more prone to errors. A quality assurance (QA) procedure tracking the source throughout dose delivery can detect dwell position and time errors in the multiple channels of the applicator. A new MVC system with integrated real time in vivo treatment delivery QA has been developed based on diodes embedded on the outer surface of the MVC...
March 6, 2019: Physica Medica: PM
M Mori, G M Cattaneo, I Dell'Oca, S Foti, R Calandrino, N G Di Muzio, C Fiorino
PURPOSE: To explore the association between planning skin dose-volume data and acute cutaneous toxicity after Radio-chemotherapy for Head and Neck (HN) cancer patients. METHODS: Seventy HN patients were treated with Helical Tomotherapy (HT) with radical intent (SIB technique: 54/66 Gy to PTV1/PTV2 in 30fr) ± chemotherapy superficial body layer 2 mm thick (SL2) was delineated on planning CT. CTCAE v4.0 acute skin toxicity data were available. Absolute average Dose-Volume Histograms (DVH) of SL2 were calculated for patients with severe (G3) and severe/moderate (G3/G2) skin acute toxicities...
February 26, 2019: Physica Medica: PM
S Spampinato, L Fokdal, E Marinovskij, S Axelsen, E M Pedersen, R Pötter, J C Lindegaard, K Tanderup
PURPOSE: To provide an analysis of dose distribution in sub-structures that could be responsible for urinary toxicity after Image-Guided Adaptive BrachyTherapy (IGABT) in Locally Advanced Cervical Cancer (LACC). METHODS: 105 LACC patients treated with radiochemotherapy and IGABT were selected. Sub-structures (bladder wall, trigone, bladder neck, urethra) were contoured on IGABT-planning MRIs. D2cm3 and D0.1cm3 , ICRU Bladder-Point (ICRU BP) and Posterior-Inferior Border of Symphysis points (PIBS, PIBS + 2 cm, PIBS - 2 cm) doses were extracted...
February 13, 2019: Physica Medica: PM
Francesca Romana Giglioli, Elena Gallio, Pierfrancesco Franco, Serena Badellino, Umberto Ricardi, Christian Fiandra
PURPOSE: To evaluate the performances of the Dolphin system for pre-treatment verification (IBA Dosimetry, Schwarzenbruck, Germany) based on transmission measurements, employing a clinical perspective. METHODS AND MATERIALS: Fifty treatment plans were verified by Dolphin and Delta4 detectors (Scandidos, Uppsala, Sweden) during the same session and subsequently by the Delta4 itself. The attenuation factor of the transmission detector (required for on-line dosimetry) was evaluated by comparing Delta4 measurements with and without Dolphin...
February 4, 2019: Physica Medica: PM
Chiara Gianoli, Sebastian Meyer, Lorena Magallanes, Chiara Paganelli, Guido Baroni, Katia Parodi
PURPOSE: An analytical simulator of ion Radiography (iRad) and Computed Tomography (iCT) for protons is proposed to serve as imaging benchmark for different detector configurations. METHODS: The analytical simulator is applied to an anthropomorphic phantom and provides iRad and iCT benchmarks. Proton trajectories are traced relying on the Most Likely Path (MLP) algorithm. To simulate the proton trajectories the Multiple Coulomb Scattering (MCS) model embedded in the MLP algorithm is extended to non-uniform water equivalent materials according to variable substitution in the well-known statistical description in uniform water...
March 2019: Physica Medica: PM
Paul Jursinic
PURPOSE: Development and implementation of a PIN diode measurement system that can measure dose on the surface of a patient, which can be compared to dose calculated by a treatment planning system. Measurements are to be possible for static or rotational photon beams and electrons. Simple calibration procedures are to be devised that require a minimum set of correction factors. METHODS: Readily available PIN type photodiodes are fabricated into devices that can be used for detection of ionizing radiation...
March 2019: Physica Medica: PM
Serenella Russo, Marco Esposito, Victor Hernandez, Jordi Saez, Francesca Rossi, Lisa Paoletti, Silvia Pini, Paolo Bastiani, Giacomo Reggiori, Giorgia Nicolini, Eugenio Vanetti, Stefano Tomatis, Marta Scorsetti, Pietro Mancosu
PURPOSE: Volumetric modulated arc therapy (VMAT) for left breast treatments allows heart sparing without compromising PTV coverage. However, this technique may require highly complex plans. Deep Inspiration Breath Hold (DIBH) procedure increases the heart-to-breast distance, facilitating the dose sparing of the heart. The aim of the present work was to investigate if the cardiac-sparing benefits of the DIBH technique were achieved with lower plan modulation and complexity than Free Breathing (FB) treatments...
March 2019: Physica Medica: PM
Giuseppe Palma, Laura Cella
PURPOSE: To present a new formalism for a robust computation of Dose-Surface Histograms (DSHs) to be exploited in the analysis of surface effects in radiation induced toxicity phenomena. METHODS: A new formal recipe for the DSH extraction is described. It is based on the computation of the Dose-Volume Histogram (DVH) on a 3D structure in the limit of vanishing thickness to approach the two-dimensional organ manifold. The theory is customized for the application to skin description...
March 2019: Physica Medica: PM
So-Yeon Park, Jung-In Kim, Do Hoon Oh, Jong Min Park
PURPOSE: The aim of this study is to evaluate the plan delivery accuracy of intensity-modulated radiation therapy (IMRT) by using textural features calculated from fluence maps. METHODS: In total, 202 IMRT plans were generated with the Trilogy (C-series linac) and TrueBeam STx systems. Fluence maps were obtained for each IMRT plan. With the fluence map, six textural features were calculated, namely angular second moment (ASM), inverse difference moment (IDM), contrast, variance, correlation, and entropy (particular displacement distances, d = 1, 5, and 10)...
March 2019: Physica Medica: PM
Riccardo Via, Andrea Pella, Francesco Romanò, Aurora Fassi, Rosalinda Ricotti, Barbara Tagaste, Alessandro Vai, Edoardo Mastella, Maria Rosaria Fiore, Francesca Valvo, Mario Ciocca, Guido Baroni
PURPOSE: At Centro Nazionale di Adroterapia Oncologica (CNAO, Pavia, Italy) ocular proton therapy (OPT) is delivered using a non-dedicated beamline. This paper describes the novel clinical workflow as well as technologies and methods adopted to achieve accurate target positioning and verification during ocular proton therapy at CNAO. METHOD: The OPT clinical protocol at CNAO prescribes a treatment simulation and a delivery phase, performed in the CT and treatment rooms, respectively...
March 2019: Physica Medica: PM
Andrea Bresolin, Giancarlo Beltramo, Livia Corinna Bianchi, Paolo Bonfanti, Marco Eulisse, Damiano Fovanna, Arcangela Maldera, Anna Stefania Martinotti, Sergio Papa, Irene Redaelli, Domenico Rocco, Gianluca Secondi, Isa Bossi Zanetti, Achille Bergantin
PURPOSE: When a lung lesion is detected by only one couple of X-ray tube and image detector integrated with CyberKnife®, the fiducial-less tracking is limited to 1-view (34% of lung treatments at Centro Diagnostico Italiano). The aim of the study was mainly to determine the margin needed to take into account the localization uncertainty along the blind view (out-of-plane direction). METHODS: 36 patients treated in 2-view tracking modality (127 fractions in total) were included in the study...
March 2019: Physica Medica: PM
Thahabah Alharthi, Sankar Arumugam, Phil Vial, Lois Holloway, David Thwaites
PURPOSE: To study the sensitivity of an Electronic Portal Imaging Device (EPID) in detecting delivery errors for VMAT lung stereotactic body radiotherapy (SBRT) using the Collapsed Arc method. METHODS: Baseline VMAT plans and plans with errors intentionally introduced were generated for 15 lung SBRT patients. Three types of errors were introduced by modifying collimator angles and multi-leaf collimator (MLC) field sizes (MLCFS) and MLC shifts by ±5, ±2, and ±1° or millimeters...
March 2019: Physica Medica: PM
Joel Poder, Dean Cutajar, Susanna Guatelli, Marco Petasecca, Andrew Howie, Joseph Bucci, Mauro Carrara, Anatoly Rosenfeld
PURPOSE: This study aims to assess the accuracy of in-vivo source tracking during real-time trans-rectal ultrasound (TRUS) based high dose rate (HDR) prostate brachytherapy (pBT) through Monte Carlo simulations of multiple HDR pBT treatments with a two-dimensional (2D) diode array, the Magic Plate 900 (MP900), embedded below the patient in a carbon-fibre couch. METHOD: Monte Carlo simulations of source positions representing three separate real-time TRUS based HDR pBT treatments were performed using the Geant4 toolkit...
March 2019: Physica Medica: PM
Ryusuke Hirai, Yukinobu Sakata, Akiyuki Tanizawa, Shinichiro Mori
PURPOSE: To improve respiratory gating accuracy and treatment throughput, we developed a fluoroscopic markerless tumor tracking algorithm based on a deep neural network (DNN). METHODS: In the learning stage, target positions were projected onto digitally reconstructed radiography (DRR) images from four-dimensional computed tomography (4DCT). DRR images were cropped into subimages of the target or surrounding regions to build a network that takes input of the image pattern of subimages and produces a target probability map (TPM) for estimating the target position...
March 2019: Physica Medica: PM
M Posiewnik, T Piotrowski
INTRODUCTION: The aim of this study was to systematize the information on adaptive radiotherapy based on cone-beam computed tomography (CBCT) imaging for patients with prostate cancers including the prostate gland only, or the prostate gland and seminal vesicles region. MATERIAL AND METHOD: A systematic literature search was carried out using the PubMed engine, based upon the following terms: adaptive radiotherapy, intensity modulated radiotherapy, volumetric modulated arc therapy and image-guided and dose-guided radiotherapy...
March 2019: Physica Medica: PM
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