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Radiotherapy error

Edward Castillo, Richard Castillo, Yevgeniy Vinogradskiy, Michele Dougherty, David Solis, Nicholas Myziuk, Andrew Thompson, Rudy Guerra, Girish Nair, Thomas Guerrero
Computed tomography (CT) derived ventilation algorithms estimate the apparent voxel volume changes within an inhale/exhale CT image pair. Transformation-based methods compute these estimates solely from the spatial transformation acquired by applying a deformable image registration (DIR) algorithm to the image pair. However, approaches based on finite difference approximations of the transformation's Jacobian have been shown to be numerically unstable. As a result, transformation-based CT ventilation is poorly reproducible with respect to both DIR algorithm and CT acquisition method...
February 19, 2019: Medical Physics
Natalie Rozanec, Zishan Allibhai, Michael Bhatti, Edwin Chan, Marlyn McIntosh, Douglas Moseley, Mojgan Taremi, Ahmar Abbas
The development of volumetric-modulated arc therapy (VMAT) in radiation therapy has allowed for improved dose escalation and a decrease in radiation-induced toxicities for patients. This article will describe a single centre's experience in development and implementation of VMAT for palliation of vertebral metastases. A retrospective planning analysis of 10 cases identified that utilization of VMAT decreases overall planning time with a statistically significant improvement in target coverage when compared with the current conventional technique...
March 2019: Journal of Medical Imaging and Radiation Sciences
José Bea-Gilabert, M Carmen Baños-Capilla, M Ángeles García-Martínez, Enrique López-Muñoz, Luis M Larrea-Rabassa
Purpose: This study aims to estimate a realistic margin in stereotactic body radiotherapy (SBRT) through examining the determination uncertainties of gross tumour volume (GTV). Methods: Three computed tomography (CT) scans were performed on each patient in different sessions as a treatment simulation. Registration of the different CT image sets was based on the fiducial marks from two stereotactic guides. GTV was defined in each one of them, as well as both the encompassing (UNI) and overlapping (INT) volumes...
2019: Journal of Radiosurgery and SBRT
Lukasz J Nowak, Ewa Pawlowska
PURPOSE: 3D printing is one of the most promising technologies that can significantly improve the efficiency of various radiotherapy (RT) procedures. In order to 3D print any structure from a DICOM file, it first has to be converted to one of the typical formats recognized by printing software, such as STL files. Due to the specificity of the data from RT planning systems and a lack of standardized methods, the geometry processing might be tricky and complex. However, all the articles presented in the literature so far either describe this step very briefly, or do not mention it at all...
February 18, 2019: Medical Physics
Deborah W Bruner, Stephanie L Pugh, W Robert Lee, James J Dignam, Daniel Low, Gregory P Swanson, Amit B Shah, Shawn Malone, Jeff M Michalski, Ian S Dayes, Samantha A Seaward, Paul L Nguyen, William A Hall, Thomas M Pisansky, Yuhchyau Chen, Howard M Sandler, Benjamin Movsas
Importance: Hypofractionated radiotherapy (HRT) would be more convenient for men with low-risk prostate cancer and cost less than conventional radiotherapy (CRT) as long as HRT is noninferior to CRT in terms of survival and quality of life (QOL) is not found to be worse. Objective: To assess differences in QOL between men with low-risk prostate cancer who are treated with HRT vs CRT. Design, Setting, and Participants: In this phase 3 randomized clinical trial, men with low-risk prostate cancer were enrolled from sites within the National Cancer Institute's National Clinical Trials Network in the United States, Canada, and Switzerland...
February 14, 2019: JAMA Oncology
Andrew L Fielding, Jessica Benitez Mendieta, Sarah Maxwell, Catherine Jones
There is an increasing need to develop methods for in vivo verification of the delivery of radiotherapy treatments. Electronic portal imaging devices (EPID's) have been demonstrated to be of use for this application. The basic principle is relatively straightforward, the EPID is used to measure a two-dimensional (2D) planar exit or portal dose map behind the patient during the treatment delivery that can provide information on any errors in linear accelerator output or changes in the patient anatomy. In this paper we focused on the effect of intra-fraction motion, particularly respiratory motion, on the measured 2D EPID dose-response...
February 5, 2019: Journal of Applied Clinical Medical Physics
Vincent Caillet, Ricky O'Brien, Douglas Moore, Per Poulsen, Tobias Pommer, Emma Colvill, Amit Sawfant, Jeremy Booth, Paul Keall
PURPOSE: Multi-leaf collimator (MLC) tracking is being clinically pioneered to continuously compensate for thoracic and pelvic motion during radiotherapy. The purpose of this work is to characterize the performance of two MLC leaf-fitting algorithms, direct optimization and piecewise optimization, for real-time motion compensation with different plan complexity and tumor trajectories. METHODS: To test the algorithms, both in silico and phantom experiments were performed...
February 5, 2019: Medical Physics
Motaz Assas, Paswach Wiriyakijja, Stefano Fedele, Stephen Porter, Richeal Ní Ríordáin
Trismus or lockjaw is the reduction in mouth opening. Radiotherapy-Induced Trismus occurs when the masticatory muscles are within range of radiation treating head and neck cancer, resulting in muscular fibrosis and trismus. We aim to assess the measurement properties of available validated patient-reported outcome measures relevant to radiotherapy-induced trismus in head and neck cancer patients. Systematic electronic searches were performed in MEDLINE and EMBASE databases to identify studies validating radiotherapy induced trismus with patient-reported outcome measures up to January 2018...
February 4, 2019: Journal of Oral Pathology & Medicine
João Otávio Bandeira Diniz, Pedro Henrique Bandeira Diniz, Thales Levi Azevedo Valente, Aristófanes Corrêa Silva, Anselmo Cardoso Paiva
BACKGROUND AND OBJECTIVE: The spinal cord is a very important organ that must be protected in treatments of radiotherapy (RT), considered an organ at risk (OAR). Excess rays associated with the spinal cord can cause irreversible diseases in patients who are undergoing radiotherapy. For the planning of treatments with RT, computed tomography (CT) scans are commonly used to delimit the OARs and to analyze the impact of rays in these organs. Delimiting these OARs take a lot of time from medical specialists, plus the fact that involves a large team of professionals...
March 2019: Computer Methods and Programs in Biomedicine
Dan Nguyen, Xun Jia, David Sher, Mu-Han Lin, Zohaib Iqbal, Hui Liu, Steve B Jiang
The treatment planning process for patients with head and neck (H&N) cancer is regarded as one of the most complicated due to large target volume, multiple prescription dose levels, and many radiation-sensitive critical structures near the target. Treatment planning for this site requires a high level of human expertise and a tremendous amount of effort to produce personalized high quality plans, taking as long as a week, which deteriorates the chances of tumor control and patient survival. To solve this problem, we propose to investigate a deep learning-based dose prediction model, Hierarchically Densely Connected U-net, based on two highly popular network architectures: U-net and DenseNet...
January 31, 2019: Physics in Medicine and Biology
Shinichiro Mori, Yukinobu Sakata, Ryusuke Hirai, Wataru Furuichi, Kazuki Shimabukuro, Ryosuke Kohno, Woong Sub Koom, Shigeru Kasai, Keiko Okaya, Yasushi Iseki
PURPOSE: To perform the final quality assurance of our fluoroscopic-based markerless tumor tracking for gated carbon-ion pencil beam scanning (C-PBS) radiotherapy using a rotating gantry system, we evaluated the geometrical accuracy and tumor tracking accuracy using a moving chest phantom with simulated respiration. METHODS: The positions of the dynamic flat panel detector (DFPD) and X-ray tube are subject to changes due to gantry sag. To compensate for this, we generated a geometrical calibration table (gantry flex map) in 15° gantry angle steps by the bundle adjustment method...
January 28, 2019: Medical Physics
Roger Trullo, Caroline Petitjean, Bernard Dubray, Su Ruan
Segmentation of organs at risk (OAR) in computed tomography (CT) is of vital importance in radiotherapy treatment. This task is time consuming and for some organs, it is very challenging due to low-intensity contrast in CT. We propose a framework to perform the automatic segmentation of multiple OAR: esophagus, heart, trachea, and aorta. Different from previous works using deep learning techniques, we make use of global localization information, based on an original distance map that yields not only the localization of each organ, but also the spatial relationship between them...
January 2019: Journal of Medical Imaging
Mingyin Jiang, Shenglin Liu, Jiaqi Gao, Qingmin Feng, Qiang Zhang
BACKGROUND The complex user interface design of radiotherapy treatment delivery systems can lead to use error and patient harm. In this study, we present the results of a comparison of 3 radiotherapy treatment delivery systems now used in China. MATERIAL AND METHODS We conducted a comprehensive usability study of 3 radiotherapy treatment delivery systems. Expert evaluation was performed through heuristic evaluation with 3 human-factors experts and 1 experienced radiation therapist for each system. User experience was assessed through perceived system usability and workload, using the National Aeronautics and Space Administration Task Load Index and the Post-Study System Usability Questionnaire...
January 20, 2019: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
Sonya Yu, Deanna Morrow, Vaughan Moutrie, David Lurie
In this prospective, exploratory study, we evaluated the positioning accuracy in a group of 15 dogs undergoing fractionated stereotactic radiotherapy for tumors affecting the head, using a modified human maxillary fixation device (Elekta Fraxion™ system). Positioning was assessed using on-board volumetric imaging, with a six-degrees-of-freedom image registration technique. Prior to treatment delivery, CBCT images were obtained and patient alignment was corrected, in both translational and rotational planes, using a six-degrees-of-freedom robotic patient positioning system (HexaPOD Evo RT System)...
January 18, 2019: Veterinary Radiology & Ultrasound
Akbar Anvari, Yannick Poirier, Amit Sawant
PURPOSE: The mechanical and geometric accuracy of small animal image-guided radiotherapy (SA-IGRT) systems is critical and is affected by a number of system-related factors. Because of the small dimensions involved in preclinical radiotherapy research, such factors can individually and/or cumulatively contribute to significant errors in the small animal radiation research. In this study, we developed and implemented a comprehensive quality assurance (QA) framework for characterizing the mechanical and geometric constancy and accuracy of the small animal radiation research platform (SARRP) system...
January 17, 2019: Medical Physics
B Yudhistiara, F Zwicker, K J Weber, P E Huber, A Ruehle, S Brons, P Haering, J Debus, S H Hauswald
BACKGROUND: The implementation of magnetic resonance imaging (MRI) guided radiotherapy (RT) continues to increase. Very limited in-vitro data on the interaction of ionizing radiation and magnetic fields (MF) have been published. In these experiments we focused on the radiation response in a MF of the TK6 human lymphoblastoid cells which are known to be highly radiosensitive due to efficient radiation-induced apoptosis. METHODS: Clonogenicity was determined 12-14 days after irradiation with 1-4 Gy 6 MV photons with or without a 1...
January 17, 2019: Radiation Oncology
Mattia Donzelli, Uwe Oelfke, Elke Brauer-Krisch
 With interlaced microbeam radiation therapy (MRT) a first kilovoltage radiotherapy (RT) concept combining spatially fractionated entrance beams and homogeneous dose distribution at the target exists. However, this technique suffers from its high sensitivity to positioning errors of the target relative to the radiation source.
 With spiral microbeam radiation therapy (spiralMRT), this publication introduces a new irradiation geometry, offering similar spatial fractionation properties as interlaced MRT, while being less vulnerable to target positioning uncertainties...
January 16, 2019: Physics in Medicine and Biology
Yoshinori Tanabe, Takayuki Ishida, Hidetoshi Eto, Tatsuhiro Sera, Yuki Emoto
To estimate the relationship between the three-dimensional (3D) displacement error of the prostate and rectal deformation for reduction of deviation between the planned and treatment dose, using multiple acquisition planning CT (MPCT) and the Dice similarity coefficient (DSC) for rectal deformation for treatment of patients with prostate cancer. The 3D displacement error between the pelvic bone and a matching fiducial marker was calculated using MPCT in 24 patients who underwent prostate volumetric-modulated arc therapy for prostate cancer...
January 11, 2019: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
Masatoshi Saito
For accurate tissue-inhomogeneity correction in radiotherapy treatment planning, the author previously proposed a conversion of the energy-subtracted computed tomography (CT) number to electron density (ΔHU-ρe conversion). The purpose of the present study was to provide a method for investigating the accuracy of a photon-counting detector (PCD) used in the ΔHU-ρe conversion by performing dual-energy CT image simulations of a PCD system with two energy bins. To optimize the tube voltage and threshold energy, the image noise and errors in ρe calibration were evaluated using three types of virtual phantoms: a 35-cm-diameter pure water phantom, 33-cm-diameter solid water surrogate phantom equipped with 16 inserts, and another solid water surrogate phantom with a 25-cm diameter...
January 9, 2019: Radiological Physics and Technology
Noemi Garau, Riccardo Via, Giorgia Meschini, Danny Lee, Paul J Keall, Marco Riboldi, Guido Baroni, Chiara Paganelli
In-room Magnetic Resonance Imaging (MRI) allows the acquisition of fast 2D cine-MRI centered in the tumor for advanced motion management in radiotherapy. To achieve 3D information during treatment, patient-specific motion models can be considered the most viable solution. However, conventional global motion models are built using a single motion surrogate, independently from the anatomical location. 
 In this work, we present a novel motion model based on regions of interest (ROIs) established on 4D Computed Tomography (4DCT) and 2D cine-MRI, aiming at accurately compensating for changes during treatment...
January 9, 2019: Physics in Medicine and Biology
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