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Dose calculation algorithms

Yelda Elcim, Bahar Dirican, Omer Yavas
PURPOSE: In this study, lung radiotherapy target volumes as well as critical organs such as the lungs, spinal cord, esophagus, and heart doses calculated using pencil beam (PB) and Monte Carlo (MC) algorithm-based treatment planning systems (TPSs) were compared. The main aim was the evaluation of calculated dose differences between the PB and MC algorithms in a highly heterogeneous medium. METHODS: A total of 6 MV photon energy conformal treatment plans were created for a RANDO lung phantom using one PB algorithm-based Precise Plan Release 2...
August 5, 2018: Journal of Applied Clinical Medical Physics
Karin M Andersson, Christina Vallhagen Dahlgren, Johan Reizenstein, Yang Cao, Anders Ahnesjö, Per Thunberg
PURPOSE: To evaluate two commercial CT metal artifact reduction (MAR) algorithms for use in proton treatment planning in the head and neck (H&N) area. METHODS: An anthropomorphic head phantom with removable metallic implants (dental fillings or neck implant) was CT-scanned to evaluate the O-MAR (Philips) and the iMAR (Siemens) algorithms. Reference images were acquired without any metallic implants in place. Water Equivalent Thickness (WET) was calculated for different path directions and compared between image sets...
August 4, 2018: Medical Physics
Cammillo R Talei Franzesi, Davide Ippolito, Luca Riva, Davide Fior, Cecilia Cangiotti, Sandro Sironi
OBJECTIVE: To evaluate image quality and radiation dose exposure of low-kV (100kV) and low contrast medium (CM) volume CT angiography (CTA) in patients candidate to Transcatheter Aortic Valve Implantation (TAVI), in comparison with standard CTA protocol. METHODS: Seventy-nine patients candidate for TAVI were prospectively enrolled in this study and examined with 256-MDCT. Forty-two patients were evaluated using study-group protocol (100kV; whole-body retrospective ECG-gating; with 50 ml of CM; iterative reconstruction algorithm) while 37 patients underwent a standard CTA study (120kV; ECG-gating for chest; 100 ml of CM; FBP reconstruction)...
August 3, 2018: British Journal of Radiology
Li Chen, Botian Huang, Xiaoyan Huang, Wufei Cao, Wenzhao Sun, Xiaowu Deng
BACKGROUND: To evaluate the difference of absorbed doses calculated to medium and to water by a Monte Carlo (MC) algorithm based treatment planning system (TPS), and to assess the potential clinical impact to dose prescription. METHODS: Thirty patients, 10 nasopharyngeal cancer (NPC), 10 lung cancer and 10 bone metastases cases, were selected for this study. For each case, the treatment plan was generated using a commercial MC based TPS and dose was calculated to medium (Dm )...
July 28, 2018: Radiation Oncology
Manuela Albisetti, Branislav Biss, Lisa Bomgaars, Leonardo R Brandão, Martina Brueckmann, Elizabeth Chalmers, Savion Gropper, Ruth Harper, Fenglei Huang, Matteo Luciani, Ivan Manastirski, Lesley G Mitchell, Igor Tartakovsky, Bushi Wang, Jacqueline M L Halton
<AbstractText Label="Background" NlmCategory="UNASSIGNED">The current standard of care (SOC) for pediatric venous thromboembolism (VTE) comprises unfractionated heparin (UFH), or low-molecular-weight heparin (LMWH) followed by LMWH or vitamin K antagonists, all of which have limitations. Dabigatran etexilate (DE) has demonstrated efficacy and safety for adult VTE and has the potential to overcome some of the limitations of the current SOC. Pediatric trials are needed to establish dosing in children and to confirm that results obtained in adults are applicable in the pediatric setting...
April 2018: Research and Practice in Thrombosis and Haemostasis
Xinrui Wang, Chengcheng Zhu, Jing Li, Andrew J Degnan, Tao Jiang, Jianping Lu
The aim of this study was to compare image quality of low tube voltage cerebral computed tomography angiography (CTA) reconstructed with knowledge-based iterative model reconstruction (IMR), filtered back projection (FBP), and hybrid iterative reconstruction (HIR).A total of 101 patients with suspected cerebrovascular diseases were enrolled and randomized into 2 groups, 100 kVp tube voltage (n = 53) and reduced tube voltage (80 kVp) (n = 48). Computed tomography data were reconstructed with IMR, FBP, and HIR algorithms...
July 2018: Medicine (Baltimore)
Yoshihiro Ueda, Naamit K Gerber, Indra J Das
OBJECTIVE: To develop a mathematical model for cardiac dose estimation for patients who have been treated for left-sided breast cancer without CT data. METHODS: After obtaining institutional review board approvals, 147 patients with left-sided breast cancer were selected that were treated supine with opposed tangents. The heart blocks from the tangential fields were removed and dose calculations were performed with 6 MV beams using an advanced algorithm. This study was performed with CT data with DRR to represent a radiographic simulator image of yesteryear treatments...
July 25, 2018: British Journal of Radiology
Raanan Marants, Eric Vandervoort, Joanna E Cygler
PURPOSE: The Synchrony respiratory motion tracking of the CyberKnife system purports to provide real-time tumor motion compensation during robotic radiosurgery. Such a complex delivery system requires thorough quality assurance. In this work, RADPOS applicability as a dose and position quality assurance tool for CyberKnife treatments is assessed quantitatively for different phantom types and breathing motions which increase in complexity to more closely resemble clinical situations. METHODS: Two radiotherapy treatment experiments were performed where dose and position were measured with the RADPOS probe housed within a Solid Water phantom...
July 25, 2018: Medical Physics
Fernando Hueso-González, Moritz Rabe, Thomas Ruggieri, Thomas Bortfeld, Joost M Verburg
We present a full-scale clinical prototype system for in vivo range verification of proton pencil-beams using the prompt gamma-ray spectroscopy method. The detection system consists of eight LaBr3 scintillators and a tungsten collimator, mounted on a rotating frame. Custom electronics and calibration algorithms have been developed for the measurement of energy- and time-resolved gamma-ray spectra during proton irradiation at a clinical dose rate. Using experimentally determined nuclear reaction cross sections and a GPU-accelerated Monte Carlo simulation, a detailed model of the expected gamma-ray emissions is created for each individual pencil-beam...
July 23, 2018: Physics in Medicine and Biology
Gerasimos A T Messaris, Dimitrios N Georgakopoulos, Petros Zampakis, Christina P Kalogeropoulou, Theodoros G Petsas, George S Panayiotakis
BACKGROUND AND PURPOSE: Brain CT Perfusion (CTP) is an X-ray imaging technique for the assessment of brain tissue perfusion, which can be used in several different entities. The aim of this study is the evaluation of the radiation dose to patients during a comprehensive brain CT prescription protocol (CPP) consisting of an unenhanced brain CT, a brain CT angiography and a CTP scan. MATERIALS AND METHODS: Eighteen patients were studied using an 80-slice CT system, with an iterative reconstruction algorithm...
July 17, 2018: Journal of Neuroradiology. Journal de Neuroradiologie
Jiasen Ma, Hok Seum Wan Chan Tseung, Michael G Herman, Chris Beltran
PURPOSE: Accuracy of dose calculation models and robustness under various uncertainties are key factors influencing the quality of intensity modulated proton therapy (IMPT) plans. To mitigate the effects of uncertainties and to improve the dose calculation accuracy, an all-scenario robust IMPT optimization based on accurate Monte Carlo (MC) dose calculation was developed. METHODS: In the all-scenario robust IMPT optimization, dose volume histograms (DVHs) were computed for the nominal case and for each uncertainty scenario...
July 18, 2018: Medical Physics
Achille Mileto, David A Zamora, Adam M Alessio, Carina Pereira, Jin Liu, Puneet Bhargava, Jonathan Carnell, Sophie M Cowan, Manjiri K Dighe, Martin L Gunn, Sooah Kim, Orpheus Kolokythas, Jean H Lee, Jeffrey H Maki, Mariam Moshiri, Ayesha Nasrullah, Ryan B O'Malley, Udo P Schmiedl, Erik V Soloff, Giuseppe V Toia, Carolyn L Wang, Kalpana M Kanal
Purpose To investigate performance in detectability of small (≤1 cm) low-contrast hypoattenuating focal lesions by using filtered back projection (FBP) and iterative reconstruction (IR) algorithms from two major CT vendors across a range of 11 radiation exposures. Materials and Methods A low-contrast detectability phantom consisting of 21 low-contrast hypoattenuating focal objects (seven sizes between 2.4 and 10.0 mm, three contrast levels) embedded into a liver-equivalent background was scanned at 11 radiation exposures (volume CT dose index range, 0...
July 17, 2018: Radiology
D Reitz, G Carl, S Schönecker, M Pazos, P Freislederer, M Niyazi, U Ganswindt, F Alongi, M Reiner, C Belka, S Corradini
BACKGROUND: Intra-fraction motion represents a crucial issue in the era of precise radiotherapy in several settings, including breast irradiation. To date, only few data exist on real-time measured intra-fraction motion in breast cancer patients. Continuous surface imaging using visible light offers the capability to monitor patient movements in three-dimensional space without any additional radiation exposure. The aim of the present study was to quantify the uncertainties of possible intra-fractional motion during breast radiotherapy...
July 16, 2018: Radiation Oncology
Pierre Bories, Sébastien Lamy, Célestine Simand, Sarah Bertoli, Cyrille Delpierre, Sandra Malak, Luc Fornecker, Stéphane Moreau, Christian Récher, Antoine Nebout
Elderly patients with acute myeloid leukemia can be treated with intensive chemotherapy, low-intensity therapy such as low-dose aracytine or hypomethylating agents, or best supportive care. The choice between these treatments is a function of many patient-related and physician-related factors. We investigated how physicians' behavioral characteristics, in particular their attitudes towards risk and uncertainty affect medical decision-making between intensive and non-intensive therapy in this setting. A nationwide cross-sectional online survey of hematologists collected data on medical decision-making for six clinical vignettes involving older acute myeloid leukemia patients that were representative of routine practice...
July 13, 2018: Haematologica
I Ebrahim, A Bryer, K Cohen, J P Mouton, W Msemburi, M Blockman
BACKGROUND: Warfarin is the most commonly used anticoagulant for both primary and secondary prevention of thromboembolism. For anticoagulation efficacy, the international normalised ratio (INR) needs to be within the therapeutic range for at least 65% of time on warfarin. OBJECTIVES: To describe INR control in patients on long-term warfarin and identified predictors of good INR control at two dedicated warfarin follow-up clinics in Cape Town, South Africa (SA). METHODS: We reviewed clinical records of patients in care at the INR clinics at Mitchell's Plain Community Health Centre and Groote Schuur Hospital...
May 25, 2018: South African Medical Journal, Suid-Afrikaanse Tydskrif Vir Geneeskunde
Tarek E Selim, Hanan A Azzam, Hayam R Ghoneim, Ahmed A Mohamed, Hossam El Wakeel, Helmy M Abu Bakr
BACKGROUND/AIMS: Data from previous reports, addressing the significance of genotype-guided dosing of warfarin in Egyptian patients, are infrequent and controversial. This study is aimed at demonstrating the validity of genetic dosing algorithms in Egyptian patients on warfarin therapy. METHODS: A total of 100 Egyptian patients on a stable maintenance daily dose of warfarin were enrolled. The predicted warfarin dose for each patient was calculated using the warfarin dosing table, the Gage and the International Warfarin Pharmacogenetics Consortium (IWPC) clinical algorithms and the Gage and the IWPC genetic algorithms and compared to the actual dose...
July 11, 2018: Acta Haematologica
Michael K Fix, Daniel Frei, Werner Volken, Dario Terribilini, Silvan Mueller, Olgun Elicin, Hossein Hemmatazad, Daniel M Aebersold, Peter Manser
PURPOSE: Although volumetric modulated arc therapy (VMAT) is a well-accepted treatment technique in radiotherapy using a coplanar delivery approach, VMAT might be further improved by including dynamic table and collimator rotations leading to dynamic trajectory radiotherapy (DTRT). In this work, an optimization procedure for DTRT was developed and the potential benefit of DTRT was investigated for different treatment sites. METHODS: For this purpose, a dedicated optimization framework for DTRT was developed using the Eclipse Scripting Research Application Programming Interface (ESRAPI)...
July 10, 2018: Medical Physics
Jiawei Chen, Haibin Chen, Zichun Zhong, Zhuoyu Wang, Brian Hrycushko, Linghong Zhou, Steve Jiang, Kevin Albuquerque, Xuejun Gu, Xin Zhen
BACKGROUND: Better knowledge of the dose-toxicity relationship is essential for safe dose escalation to improve local control in cervical cancer radiotherapy. The conventional dose-toxicity model is based on the dose volume histogram, which is the parameter lacking spatial dose information. To overcome this limit, we explore a comprehensive rectal dose-toxicity model based on both dose volume histogram and dose map features for accurate radiation toxicity prediction. METHODS: Forty-two cervical cancer patients treated with combined external beam radiotherapy (EBRT) and brachytherapy (BT) were retrospectively studied, including 12 with Grade ≥ 2 rectum toxicity and 30 patients with Grade 0-1 toxicity (non-toxicity patients)...
July 6, 2018: Radiation Oncology
Ali Ghanbarzadeh, Majid Pouladian, Ali Shabestani Monfared, Seied Rabi Mahdavi
This article introduces a new framework for beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) using the Scatter Search Based Algorithm. The potential benefits of plans employing the coplanar optimized beam sets are also examined. In the proposed beam angle selection algorithm, the problem is solved in two steps. Initially, the gantry angles are selected using the Scatter Search Based Algorithm, which is a global optimization method. Then, for each beam configuration, the intensity profile is calculated by the conjugate gradient method to score each beam angle set chosen...
2018: Computational and Mathematical Methods in Medicine
Christoph Speier, Giampaolo Pileggi, David Izquierdo-Garcia, Ciprian Catana, Gregory Sharp, Maria Francesca Spadea, Christoph Bert, Joao Seco
PURPOSE: To investigate advanced multi-modal methods for pseudo-CT generation from standard MRI sequences and to validate the results by IMRT and VMAT radiation therapy plans. We present two novel methods which employ key techniques to enhance pseudo-CTs and we investigate the impact on image quality and applicability for IMRT and VMAT therapy planning. MATERIALS AND METHODS: The dataset contains CTs and MRIs from 15 patients who underwent cranial radiotherapy. For each patient pseudo-CTs of the head were generated with a patch-based and a voxel-based algorithm...
June 29, 2018: International Journal of Radiation Oncology, Biology, Physics
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