Read by QxMD icon Read

Physica Medica: PM

Baderaldeen A Altazi, Daniel C Fernandez, Geoffrey G Zhang, Samuel Hawkins, Syeda M Naqvi, Youngchul Kim, Dylan Hunt, Kujtim Latifi, Matthew Biagioli, Puja Venkat, Eduardo G Moros
Quantitative image features, also known as radiomic features, have shown potential for predicting treatment outcomes in several body sites. We quantitatively analyzed18 Fluorine-fluorodeoxyglucose (18 F-FDG) Positron Emission Tomography (PET) uptake heterogeneity in the Metabolic Tumor Volume (MTV) of eighty cervical cancer patients to investigate the predictive performance of radiomic features for two treatment outcomes: the development of distant metastases (DM) and loco-regional recurrent disease (LRR). We aimed to fit the highest predictive features in multiple logistic regression models (MLRs)...
February 20, 2018: Physica Medica: PM
Nathanael Lampe, Mathieu Karamitros, Vincent Breton, Jeremy M C Brown, Dousatsu Sakata, David Sarramia, Sébastien Incerti
We extended a generic Geant4 application for mechanistic DNA damage simulations to an Escherichia coli cell geometry, finding electron damage yields and proton damage yields largely in line with experimental results. Depending on the simulation of radical scavenging, electrons double strand breaks (DSBs) yields range from 0.004 to 0.010 DSB Gy-1 Mbp-1, while protons have yields ranging from 0.004 DSB Gy-1 Mbp-1 at low LETs and with strict assumptions concerning scavenging, up to 0.020 DSB Gy-1 Mbp-1 at high LETs and when scavenging is weakest...
January 19, 2018: Physica Medica: PM
Sogol Givehchi, Mohammad Javad Safari, Sock Keow Tan, Mohammad Nazri Bin Md Shah, Fadhli Bin Mohamed Sani, Raja Rizal Azman, Zhonghua Sun, Chai Hong Yeong, Kwan Hoong Ng, Jeannie Hsiu Ding Wong
PURPOSE: Accurate determination of the bifurcation angle and correlation with plaque buildup may lead to the prediction of coronary artery disease (CAD). This work evaluates two techniques to measure bifurcation angles in 3D space using coronary computed tomography angiography (CCTA). MATERIALS AND METHODS: Nine phantoms were fabricated with different bifurcation angles ranging from 55.3° to 134.5°. General X-ray and CCTA were employed to acquire 2D and 3D images of the bifurcation phantoms, respectively...
January 16, 2018: Physica Medica: PM
Marco Brambilla
No abstract text is available yet for this article.
January 10, 2018: Physica Medica: PM
Marianne Camille Aznar, Samantha Warren, Mischa Hoogeman, Mirjana Josipovic
Stereotactic body radiotherapy (SBRT) for lung tumours has been gaining wide acceptance in lung cancer. Here, we review the technological evolution of SBRT delivery in lung cancer, from the first treatments using the stereotactic body frame in the 1990's to modern developments in image guidance and motion management. Finally, we discuss the impact of current technological approaches on the requirements for quality assurance as well as future technological developments.
January 10, 2018: Physica Medica: PM
Hamid Abdollahi, Shayan Mostafaei, Susan Cheraghi, Isaac Shiri, Seied Rabi Mahdavi, Anoshirvan Kazemnejad
OBJECTIVES: Immediately or after head-and-neck (H&N) cancer chemoradiotherapy (CRT), patients may undergone significant sensorineural hearing loss (SNHL) which could affect their quality of life. Radiomic feature analysis is proposed to predict SNHL induced by CRT. MATERIAL AND METHODS: 490 image features of 94 cochlea from 47 patients treated with three dimensional conformal RT (3DCRT) for different H&N cancers were extracted from CT images. Different machine learning (ML) algorithms and also least absolute shrinkage and selection operator (LASSO) penalized logistic regression were implemented on radiomic features for feature selection, classification and prediction...
January 9, 2018: Physica Medica: PM
Pietro Mancosu, Andrew Nisbet, Núria Jornet
Stereotactic body radiation therapy (SBRT) has become a standard treatment for non-operable patients with early stage non-small cell lung cancer (NSCLC). In this context, medical physics community has largely helped in the starting and the growth of this technique. In fact, SBRT requires the convergence of many different features for delivering large doses in few fractions to small moving target in an heterogeneous medium. The special issue of last month, was focused on the different physics challenges in lung SBRT...
January 9, 2018: Physica Medica: PM
Andreia C Freitas, Matthieu Ruthven, Redha Boubertakh, Marc E Miquel
PURPOSE: This study aims to improve clinical reliability of real-time Magnetic Resonance Imaging (rt-MRI) in the visualisation of velopharyngeal motion during speech. METHODS: Seven subjects were imaged at 3T during natural phonation. Speech rt-MRI methodologies were investigated with (i) a comparison of commercial Cartesian and non-Cartesian (radial and spiral) rt-MRI sequences and (ii) investigation of further improvement with accelerated radial acquisition and offline reconstruction methodology...
February 2018: Physica Medica: PM
Daisuke Kawahara, Hisashi Nakano, Shuichi Ozawa, Akito Saito, Tomoki Kimura, Tatsuhiko Suzuki, Masato Tsuneda, Sodai Tanaka, Yoshimi Ohno, Yuji Murakami, Yasushi Nagata
OBJECTIVES: We examine the contrast agent Lipiodol effect on the relative biological effectiveness (RBE) values for flattening filter free (FFF) and flattening filter (FF) beams of 6 MV-Xray (6 MVX) and 10 MVX. METHODS: Lipiodol was placed at 5 cm depth in water. According to the microdosimetric kinetic model, the RBE values for killing the human liver hepatocellular cells were calculated from dose and lineal energy (yd(y)) from Monte Carlo simulations. RBE200kVX and RBECo were defined as the ratios of dose using reference radiation (200 kVX, Co-ɤ) to the dose of test radiation (FFF and FF beams for 6 MV and 10 MV) to produce the same biological effects...
February 2018: Physica Medica: PM
Katharina Bell, Yvonne Dzierma, Melanie Morlo, Frank Nüsken, Norbert Licht, Christian Rübe
BACKGROUND: In order to consider potential positioning errors there are different recipes for safety-margins for CTV-to-PTV expansion. The aim of this study is to simulate the effect of positioning inaccuracy with clinically realistic patient treatment plans. METHODS: For a collective of 40 prostate patients, the isocenter was shifted back appropriately to the applied table shifts after positioning verification, simulating that no positioning correction had been performed and the treatment plans were recalculated...
February 2018: Physica Medica: PM
Jaime Martínez Ortega, María Pinto Monedero, Nuria Gómez González, Naresh B Tolani, Pablo Castro Tejero, Miguel Castanedo Álvarez, Luis Núñez Martín, R Sánchez Montero
PURPOSE: To develop a transit-dose portal dosimetry method based on a commercial collapsed-cone algorithm. METHODS: A Varian Clinac21EX (Varian Medical Systems, USA), equipped with an amorphous-silicon EPID aS1000, was used. Dose calculations were performed with the collapsed-cone algorithm of Pinnacle3 v8.0 m (Philips Medical Systems, USA). A model for the energy of 6 MV was made in Pinnacle3 and afterwards validated for clinical use. A virtual phantom with different densities was contoured and superimposed on the patient images, simulating the presence of the EPID during the treatment...
February 2018: Physica Medica: PM
Jie Wei, Ming Chao
PURPOSE: We presented a feasibility study to extract the diaphragm motion from the inferior contrast cone beam computed tomography (CBCT) projection images using a constrained linear regression optimization algorithm. METHODS: The shape of the diaphragm was fitted by a parabolic function which was initialized by five manually placed points on the diaphragm contour of a pre-selected projection. A constrained linear regression model by exploiting the spatial, algebraic, and temporal constraints of the diaphragm, approximated by a parabola, was employed to estimate the parameters...
February 2018: Physica Medica: PM
Hannu Jarvinen, Jad Farah, Teemu Siiskonen, Olivera Ciraj-Bjelac, Jérémie Dabin, Eleftheria Carinou, Joanna Domienik-Andrzejewska, Dariusz Kluszczynski, Željka Knežević, Renata Kopec, Marija Majer, Francoise Malchair, Anna Negri, Piotr Pankowski, Sandra Sarmento, Annalisa Trianni
PURPOSE: The feasibility of setting-up generic, hospital-independent dose alert levels to initiate vigilance on possible skin injuries in interventional procedures was studied for three high-dose procedures (chemoembolization (TACE) of the liver, neuro-embolization (NE) and percutaneous coronary intervention (PCI)) in 9 European countries. METHODS: Gafchromic® films and thermoluminescent dosimeters (TLD) were used to determine the Maximum Skin Dose (MSD). Correlation of the online dose indicators (fluoroscopy time, kerma- or dose-area product (KAP or DAP) and cumulative air kerma at interventional reference point (Ka,r )) with MSD was evaluated and used to establish the alert levels corresponding to a MSD of 2 Gy and 5 Gy...
February 2018: Physica Medica: PM
Cristina Garibaldi, Cristiana Fodor, Giulia Riva, Damaris Patricia Rojas, Samantha Dicuonzo, Elisa Pace, Giuseppe Fanetti, Paolo De Marco, Veronica Dell'acqua, Giulia Marvaso, Maria Cristina Leonardi, Roberta Lazzari, Federica Cattani, Marta Cremonesi, Roberto Orecchia, Barbara Alicja Jereczek-Fossa
PURPOSE: To evaluate inter-fraction tumor localization errors (TE) in the RapidArc® treatment of pelvic cancers based on CBCT. Appropriate CTV-to PTV margins in a non-IGRT scenario have been proposed. METHODS: Data of 928 patients with prostate, gynecological, and rectum/anal canal cancers were retrospectively analyzed to determine systematic and random localization errors. Two protocols were used: daily online IGRT (d-IGRT) and weekly IGRT. The latter consisted in acquiring a CBCT for the first 3 fractions and subsequently once a week...
February 2018: Physica Medica: PM
S Kottou, N Kollaros, C Plemmenos, I Mastorakou, S C Apostolopoulou, V Tsapaki
This study aimed to evaluate paediatric radiation doses in a dedicated cardiology hospital, with the objective of characterising patterns in dose variation. The ultimate purpose was to define Local (Institutional) Diagnostic Reference Levels (LDRLs) for different types of paediatric cardiac interventional procedures (IC), according to patient age. From a total of 710 cases performed during three consecutive years, by operators with more than 15 years of experience, the age was noted in only 477 IC procedures...
February 2018: Physica Medica: PM
M Lazzeroni, J Uhrdin, S Carvalho, W van Elmpt, P Lambin, A Dasu, P Wersäll, I Toma-Dasu
PURPOSE: Early assessment of tumour response to treatment with repeated FDG-PET-CT imaging has potential for treatment adaptation but it is unclear what the optimal time window for this evaluation is. Previous studies indicate that changes in SUVmean and the effective radiosensitivity (αeff , accounting for uptake variations and accumulated dose until the second FDG-PET-CT scan) are predictive of 2-year overall survival (OS) when imaging is performed before radiotherapy and during the second week...
February 2018: Physica Medica: PM
Mazen Soufi, Hidetaka Arimura, Takahiro Nakamoto, Taka-Aki Hirose, Saiji Ohga, Yoshiyuki Umezu, Hiroshi Honda, Tomonari Sasaki
PURPOSE: We aimed to explore the temporal stability of radiomic features in the presence of tumor motion and the prognostic powers of temporally stable features. METHODS: We selected single fraction dynamic electronic portal imaging device (EPID) (n = 275 frames) and static digitally reconstructed radiographs (DRRs) of 11 lung cancer patients, who received stereotactic body radiation therapy (SBRT) under free breathing. Forty-seven statistical radiomic features, which consisted of 14 histogram-based features and 33 texture features derived from the graylevel co-occurrence and graylevel run-length matrices, were computed...
February 2018: Physica Medica: PM
Kai-Uwe Schässburger, Stefan Paepke, Ariel Saracco, Edward Azavedo, Christina Ekström, Hans Wiksell
Minimally invasive biopsies are a cornerstone of breast cancer management with ultrasound being the preferred guidance modality. New developments in breast cancer management and advances in imaging technologies bring new challenges to current biopsy methodologies. A new biopsy device (NeoNavia® biopsy system, 14 G) was developed. It incorporates a pneumatic needle insertion mechanism that is intended to provide better control of needle progression and enable stepwise insertion without noticeable deformation or displacement of surrounding tissue as visualized under ultrasound...
February 2018: Physica Medica: PM
Mohammad Haekal, Hidetaka Arimura, Taka-Aki Hirose, Yusuke Shibayama, Saiji Ohga, Junichi Fukunaga, Yoshiyuki Umezu, Hiroshi Honda, Tomonari Sasaki
PURPOSE: To analyze the uncertainties of the rectum due to anisotropic shape variations by using a statistical point distribution model (PDM). MATERIALS AND METHODS: The PDM was applied to the rectum contours that were delineated on planning computed tomography (CT) and cone-beam CT (CBCT) at 80 fractions of 11 patients. The standard deviations (SDs) of systematic and random errors of the shape variations of the whole rectum and the region in which the rectum overlapped with the PTV (ROP regions) were derived from the PDMs at all fractions of each patient...
February 2018: Physica Medica: PM
Ernesto Amato, Antonio Italiano, Lucrezia Auditore, Sergio Baldari
The availability of a resource collecting dose factors for the evaluation of the absorbed doses from external exposure during the manipulation of radioactive substances is fundamental for radiological protection purposes. Monte Carlo simulations are useful for the accurate calculation of dose distributions in complex geometries, particularly in presence of extended spectra of multi-radiation sources. We considered, as possible irradiation scenarios, a point source, a uniform planar source resembling a contaminated surface, several source volumes contained in plastic or glass receptacles, and the direct skin contamination case, implementing the corresponding Monte Carlo simulations in GAMOS (GEANT4-based Architecture for Medicine-Oriented Simulations)...
February 2018: Physica Medica: PM
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"