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Physica Medica: PM

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https://www.readbyqxmd.com/read/30342982/dependence-of-apparent-diffusion-coefficient-measurement-on-diffusion-gradient-direction-and-spatial-position-a-quality-assurance-intercomparison-study-of-forty-four-scanners-for-quantitative-diffusion-weighted-imaging
#1
Luca Fedeli, Giacomo Belli, Antonio Ciccarone, Angela Coniglio, Marco Esposito, Marco Giannelli, Lorenzo Nicola Mazzoni, Luca Nocetti, Roberto Sghedoni, Roberto Tarducci, Luisa Altabella, Eleonora Belligotti, Matteo Benelli, Margherita Betti, Rocchina Caivano, Marco Carni', Andrea Chiappiniello, Sara Cimolai, Fabiola Cretti, Christian Fulcheri, Chiara Gasperi, Mara Giacometti, Fabrizio Levrero, Domenico Lizio, Marta Maieron, Simona Marzi, Lorella Mascaro, Silvia Mazzocchi, Gabriele Meliado', Sabrina Morzenti, Linhsia Noferini, Nadia Oberhofer, Maria Grazia Quattrocchi, Alessandra Ricci, Adriana Taddeucci, Leonardo Tenori, Claudio Luchinat, Gianni Gobbi, Cesare Gori, Simone Busoni
PURPOSE: To propose an MRI quality assurance procedure that can be used for routine controls and multi-centre comparison of different MR-scanners for quantitative diffusion-weighted imaging (DWI). MATERIALS AND METHODS: 44 MR-scanners with different field strengths (1 T, 1.5 T and 3 T) were included in the study. DWI acquisitions (b-value range 0-1000 s/mm2 ), with three different orthogonal diffusion gradient directions, were performed for each MR-scanner...
October 17, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30340846/occupational-radiation-dose-limits-towards-breaking-the-one-size-fits-all-paradigm
#2
LETTER
Iftikhar Ahmad
No abstract text is available yet for this article.
October 16, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30314733/integration-of-diffusion-magnetic-resonance-tractography-into-tomotherapy-radiation-treatment-planning-for-high-grade-gliomas
#3
Luisa Altabella, Sara Broggi, Paola Mangili, Gian Marco Conte, Valentina Pieri, Antonella Iadanza, Antonella Del Vecchio, Nicoletta Anzalone, Nadia di Muzio, Riccardo Calandrino, Andrea Falini, Antonella Castellano
INTRODUCTION: Fractionated radiotherapy in brain tumors is commonly associated with several detrimental effects, largely related to the higher radiosensitivity of the white matter (WM) with respect to gray matter. However, no dose constraints are applied to preserve WM structures at present. Magnetic Resonance (MR) Tractography is the only technique that allows to visualize in vivo the course of WM eloquent tracts in the brain. In this study, the feasibility of integrating MR Tractography in tomotherapy treatment planning has been investigated, with the aim to spare eloquent WM regions from the dose delivered during treatment...
October 9, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30314732/normalized-glandular-dose-coefficients-in-mammography-digital-breast-tomosynthesis-and-dedicated-breast-ct
#4
A Sarno, G Mettivier, F Di Lillo, R M Tucciariello, K Bliznakova, P Russo
PURPOSE: To provide mean glandular dose (MGD) estimates via Monte Carlo (MC) simulations as a function of the breast models and scan parameters in mammography, digital breast tomosynthesis (DBT) and dedicated breast CT (BCT). METHODS: The MC code was based on GEANT4 toolkit. The simulated compressed breast was either a cylinder with a semi-circular section or ad hoc shaped for oblique view (MLO). In DBT we studied the influence of breast models and exam parameters on the T-factors (i...
October 9, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30197097/beam-parameters-optimization-and-characterization-for-a-turning-linac-for-protontherapy
#5
Caterina Cuccagna, Vittorio Bencini, Stefano Benedetti, Daniele Bergesio, Pedro Carrio Perez, Enrico Felcini, Adriano Garonna, Wioletta S Kozłowska, Mohammad Varasteh Anvar, Vasilis Vlachoudis, Ugo Amaldi
TULIP (TUrning LInac for Protontherapy) is a novel compact accelerator system for protontherapy mounted on a rotating gantry (Amaldi et al., 2013, 2010, 2009). Its high-energy Linac has the unique property of being able to modulate the beam energy from one pulse to the next, in only a couple of milliseconds. The main purpose of this study is to optimize the properties of the beam exiting the Linac to make them compatible to medical therapy and to characterize their medical physics properties for later implementation in a Treatment Planning System...
September 6, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337015/monte-carlo-dose-in-a-prosthesis-phantom-based-on-exact-geometry-vs-streak-artefact-contaminated-ct-data-as-benchmarked-against-gafchromic-film-measurements
#6
Nicholas Ade, O M Oderinde, F C P du Plessis
PURPOSE: In radiotherapy, accurate calculation of patient radiation dose is very important for good clinical outcome. In the presence of metallic implants, the dose calculation accuracy could be compromised by metal artefacts generated in computed tomography (CT) images of patients. This study investigates the influence of metal-induced CT artefacts on MC dose calculations in a pelvic prosthesis phantom. METHODS: A pelvic phantom containing unilateral Ti prosthesis was CT-scanned and accurate Hounsfield unit (HU) values were assigned to known materials of the phantom as opposed to HU values produced through the artefact CT images of the phantom...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337014/dosimetric-effects-of-brass-mesh-bolus-on-skin-dose-and-dose-at-depth-for-postmastectomy-chest-wall-irradiation
#7
Zakiya S Al-Rahbi, Dean L Cutajar, Peter Metcalfe, Anatoly B Rosenfeld
PURPOSE: To investigate the feasibility of using the brass mesh bolus as an alternative to tissue- equivalent bolus for post mastectomy chest wall cancer by characterizing the dosimetric effects of the 2-mm fine brass bolus on both the skin dose, the dose at depth and spatial distribution. MATERIALS AND METHODS: Surface dose and percent depth dose data were acquired for a 6 MV photon beam in a solid water phantom using MOSkin™, Gafchromic EBT3 film and an Advanced Markus ionization chamber...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337013/integral-dose-based-inverse-optimization-objective-function-promises-lower-toxicity-in-head-and-neck
#8
Ivaylo B Mihaylov, Eduardo G Moros
PURPOSE: The voxels in a CT data sets contain density information. Besides its use in dose calculation density has no other application in modern radiotherapy treatment planning. This work introduces the use of density information by integral dose minimization in radiotherapy treatment planning for head-and-neck squamous cell carcinoma (HNSCC). MATERIALS AND METHODS: Eighteen HNSCC cases were studied. For each case two intensity modulated radiotherapy (IMRT) plans were created: one based on dose-volume (DV) optimization, and one based on integral dose minimization (Energy hereafter) inverse optimization...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337012/effect-of-accounting-for-interfractional-ctv-shape-variations-in-ptv-margins-on-prostate-cancer-radiation-treatment-plans
#9
Taka-Aki Hirose, Hidetaka Arimura, Yusuke Shibayama, Jun-Ichi Fukunaga, Saiji Ohga
PURPOSE: The aim of this study was to account for interfractional clinical target volume (CTV) shape variation and apply this to the planning target volume (PTV) margin for prostate cancer radiation treatment plans. METHODS: Interfractional CTV shape variations were estimated from weekly cone-beam computed tomography (CBCT) images using statistical point distribution models. The interfractional CTV shape variation was taken into account in the van Herk's margin formula...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337011/rotationally-resliced-3d-prostate-segmentation-of-mr-images-using-bhattacharyya-similarity-and-active-band-theory
#10
Zhixian Tang, Manning Wang, Zhijian Song
PURPOSE: In this article, we propose a novel, semi-automatic segmentation method to process 3D MR images of the prostate using the Bhattacharyya coefficient and active band theory with the goal of providing technical support for computer-aided diagnosis and surgery of the prostate. METHODS: Our method consecutively segments a stack of rotationally resectioned 2D slices of a prostate MR image by assessing the similarity of the shape and intensity distribution in neighboring slices...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337010/a-straightforward-multiparametric-quality-control-protocol-for-proton-magnetic-resonance-spectroscopy-validation-and-comparison-of-various-1-5-t-and-3-t-clinical-scanner-systems
#11
Roberto Sghedoni, Angela Coniglio, Lorenzo Nicola Mazzoni, Simone Busoni, Giacomo Belli, Roberto Tarducci, Luca Nocetti, Luca Fedeli, Marco Esposito, Antonio Ciccarone, Luisa Altabella, Alessandro Bellini, Luca Binotto, Rocchina Caivano, Marco Carnì, Alessandra Ricci, Sara Cimolai, Davide D'Urso, Chiara Gasperi, Fabrizio Levrero, Paola Mangili, Sabrina Morzenti, Andrea Nitrosi, Nadia Oberhofer, Nicoletta Parruccini, Alessandra Toncelli, Lucia Maria Valastro, Cesare Gori, Gianni Gobbi, Marco Giannelli
PURPOSE: The aim of this study was to propose and validate across various clinical scanner systems a straightforward multiparametric quality assurance procedure for proton magnetic resonance spectroscopy (MRS). METHODS: Eighteen clinical 1.5 T and 3 T scanner systems for MRS, from 16 centres and 3 different manufacturers, were enrolled in the study. A standard spherical water phantom was employed by all centres. The acquisition protocol included 3 sets of single (isotropic) voxel (size 20 mm) PRESS acquisitions with unsuppressed water signal and acquisition voxel position at isocenter as well as off-center, repeated 4/5 times within approximately 2 months...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337009/establishing-the-european-diagnostic-reference-levels-for-interventional-cardiology
#12
T Siiskonen, O Ciraj-Bjelac, J Dabin, A Diklic, J Domienik-Andrzejewska, J Farah, J M Fernandez, A Gallagher, C J Hourdakis, S Jurkovic, H Järvinen, J Järvinen, Ž Knežević, C Koukorava, C Maccia, M Majer, F Malchair, L Riccardi, C Rizk, R Sanchez, M Sandborg, M Sans Merce, D Segota, J Sierpowska, G Simantirakis, L Sukupova, Z Thrapsanioti, E Vano
Interventional cardiac procedures may be associated with high patient doses and therefore require special attention to protect the patients from radiation injuries such as skin erythema, cardiovascular tissue reactions or radiation-induced cancer. In this study, patient exposure data is collected from 13 countries (37 clinics and nearly 50 interventional rooms) and for 10 different procedures. Dose data was collected from a total of 14,922 interventional cardiology procedures. Based on these data European diagnostic reference levels (DRL) for air kerma-area product are suggested for coronary angiography (CA, DRL = 35 Gy cm2 ), percutaneous coronary intervention (PCI, 85 Gy cm2 ), transcatheter aortic valve implantation (TAVI, 130 Gy cm2 ), electrophysiological procedures (12 Gy cm2 ) and pacemaker implantations...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337008/evaluation-of-optimization-workflow-using-design-of-experiment-doe-for-various-field-configurations-in-volumetric-modulated-arc-therapy
#13
Kentaro Miki, Akito Saito, Takeo Nakashima, Yuji Murakami, Tomoki Kimura, Ikuno Nishibuchi, Yasushi Nagata
PURPOSE: In volumetric-modulated arc therapy (VMAT), field configurations such as couch or arc angles are defined manually or using a template. A field configuration is reselected through trial-and-error in the case of undesirable resultant planning. To efficiently plan for desirable quality, configurations should be assessed before dose calculation. Design of experiments (DoE) is an optimization technique that efficiently reveals the influence of inputs on outputs. We developed an original tool using DoE to determine the field configuration selection and evaluated the efficacy of this workflow for clinical practice...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337007/evaluation-of-medical-physics-training-in-radiology-residency-in-67-countries
#14
Madan M Rehani, Ruben Pauwels, Bhavya Rehani
PURPOSE: The main aim of medical physics training in radiology residency is to have appropriate and safer imaging of patients and safety of personnel. The need to have adequate coverage of medical physics and radiation safety in curricula of radiology residency is well perceived, but it is not known how far it is implemented in practice. METHODS: We have analysed the data from 67 countries on medical physics teaching and assessment of residents in radiology programs, considering differences between countries in function of their human development index (HDI)...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337006/early-tumor-response-prediction-for-lung-cancer-patients-using-novel-longitudinal-pattern-features-from-sequential-pet-ct-image-scans
#15
Giulia Buizza, Iuliana Toma-Dasu, Marta Lazzeroni, Chiara Paganelli, Marco Riboldi, Yongjun Chang, Örjan Smedby, Chunliang Wang
PURPOSE: A new set of quantitative features that capture intensity changes in PET/CT images over time and space is proposed for assessing the tumor response early during chemoradiotherapy. The hypothesis whether the new features, combined with machine learning, improve outcome prediction is tested. METHODS: The proposed method is based on dividing the tumor volume into successive zones depending on the distance to the tumor border. Mean intensity changes are computed within each zone, for CT and PET scans separately, and used as image features for tumor response assessment...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337005/in-vivo-dosimetry-comparison-of-supraclavicular-junction-dose-for-breast-and-chest-wall-patients-with-and-without-deep-inspiration-breath-hold-dibh
#16
Elizabeth Ruth Claridge Mackonis, Reuben Patrick Estoesta, Susan Carroll
PURPOSE: The use of deep inspiration breath-hold (DIBH) for patients with left-sided breast cancer reduces cardiac dose, with the aim of reducing the risk of major coronary events. However, this technique has not been universally adopted for patients requiring regional nodal irradiation (RNI) with one concern related to the junction dose. This study evaluates the dose received at the junction for both DIBH and free-breathing patients having tangential breast/chest wall radiation and regional nodal radiation treated with 3D-conformal or hybrid IMRT radiotherapy...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337004/dosimetric-and-localization-accuracy-of-elekta-high-definition-dynamic-radiosurgery
#17
Daniel L Saenz, Ying Li, Karl Rasmussen, Sotirios Stathakis, Evangelos Pappas, Niko Papanikolaou
BACKGROUND AND PURPOSE: With the increasingly prominent role of stereotactic radiosurgery in radiation therapy, there is a clinical need for robust, efficient, and accurate solutions for targeting multiple sites with one patient setup. The end-to-end accuracy of high definition dynamic radiosurgery with Elekta treatment planning and delivery systems was investigated in this study. MATERIALS AND METHODS: A patient-derived CT scan was used to create a radiosurgery plan to seven targets in the brain...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337003/error-detection-during-vmat-delivery-using-epid-based-3d-transit-dosimetry
#18
B Mijnheer, A Jomehzadeh, P González, I Olaciregui-Ruiz, R Rozendaal, P Shokrani, H Spreeuw, R Tielenburg, A Mans
PURPOSE: To investigate the effectiveness of an EPID-based 3D transit dosimetry system in detecting deliberately introduced errors during VMAT delivery. METHODS: An Alderson phantom was irradiated using four VMAT treatment plans (one prostate, two head-and-neck and one lung case) in which delivery, thickness and setup errors were introduced. EPID measurements were performed to reconstruct 3D dose distributions of "error" plans, which were compared with "no-error" plans using the mean gamma (γmean ), near-maximum gamma (γ1% ) and the difference in isocenter dose (ΔDisoc ) as metrics...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337002/temporal-separation-of-cerenkov-radiation-and-scintillation-using-artificial-neural-networks-in-clinical-linacs
#19
Levi Madden, James Archer, Enbang Li, Dean Wilkinson, Anatoly Rosenfeld
The irradiation of scintillator-fiber optic dosimeters by clinical LINACs results in the measurement of scintillation and Cerenkov radiation. In scintillator-fiber optic dosimetry, the scintillation and Cerenkov radiation responses are separated to determine the dose deposited in the scintillator volume. Artificial neural networks (ANNs) were trained and applied in a novel single probe method for the temporal separation of scintillation and Cerenkov radiation. Six dose profiles were measured using the ANN, with the dose profiles compared to those measured using background subtraction and an ionisation chamber...
October 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30337001/clinical-implementations-of-4d-pencil-beam-scanned-particle-therapy-report-on-the-4d-treatment-planning-workshop-2016-and-2017
#20
Petra Trnková, Barbara Knäusl, Oxana Actis, Christoph Bert, Aleksandra K Biegun, Till T Boehlen, Hugo Furtado, Jamie McClelland, Shinichiro Mori, Ilaria Rinaldi, Antoni Rucinski, Antje C Knopf
In 2016 and 2017, the 8th and 9th 4D treatment planning workshop took place in Groningen (the Netherlands) and Vienna (Austria), respectively. This annual workshop brings together international experts to discuss research, advances in clinical implementation as well as problems and challenges in 4D treatment planning, mainly in spot scanned proton therapy. In the last two years several aspects like treatment planning, beam delivery, Monte Carlo simulations, motion modeling and monitoring, QA phantoms as well as 4D imaging were thoroughly discussed...
October 2018: Physica Medica: PM
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