37 results match your criteria cirs thorax


Dosimetric evaluation of different planning techniques based on flattening filter-free beams for central and peripheral lung stereotactic body radiotherapy.

Biomed Phys Eng Express 2021 Oct 12. Epub 2021 Oct 12.

Department of Radiotherapy, Government Medical College Patiala, Sangrur Road, Patiala, Punjab, 147001, INDIA.

This study aimed to dosimetrically compare and evaluate the flattening filter-free (FFF) photon beam-based three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) for lungstereotactic body radiotherapy (SBRT). RANDO phantom computed tomography (CT) images were used for treatment planning. Gross tumor volumes (GTVs) were delineated in the central and peripheral lung locations. Read More

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October 2021

Accuracy Evaluation of EPL and ETAR Algorithms in the Treatment Planning Systems using CIRS Thorax Phantom.

J Biomed Phys Eng 2021 Aug 1;11(4):483-496. Epub 2021 Aug 1.

PhD, Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.

Background: It is recommended for each set of radiation data and algorithm that subtle deliberation is done regarding dose calculation accuracy. Knowing the errors in dose calculation for each treatment plan will result in an accurate estimate of the actual dose achieved by the tumor.

Objective: This study aims to evaluate the equivalent path length (EPL) and equivalent tissue air ratio (ETAR) algorithms in radiation dose calculation. Read More

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Technical Note: End-to-end verification of an MR-Linac using a dynamic motion phantom.

Med Phys 2021 Sep 26;48(9):5479-5489. Epub 2021 Jul 26.

Department of Radiation Physics, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China.

Purpose: MR-Linac integrates an MRI scanner and a linear accelerator to provide adaptive radiation treatment. Superior tissue contrast and real-time imaging can give the clinicians confidence to reduce the margins of the planning target volume (PTV). The purpose of this study was to verify the dosimetric accuracy of an MR-Linac system in treating a moving target and assess the error with different motion patterns and adaptation methods. Read More

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September 2021

Commissioning and quality assurance of Euromechanics add-on multileaf collimator.

Biomed Phys Eng Express 2020 12 21;7(1). Epub 2020 Dec 21.

Department of Medical Physics, Tehran University of Medical Science, Tehran, Iran.

In this study, the beam characteristics of a Euromechanics add-on MLC that has been installed on a Varian CLINAC 2100 C/D linear accelerator are presented. This was the first installation of 60-leaf PMLC from Euromechanics Company worldwide and all mechanical and dosimetric parameters were measured before clinical use of this kind of MLC. Mechanical tests were executed for different gantry and collimator angles. Read More

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December 2020

Technical Note: Performance of CyberKnife tracking using low-dose CT and kV imaging.

Med Phys 2020 Dec 28;47(12):6163-6170. Epub 2020 Oct 28.

Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, 94143, USA.

Purpose: To investigate the effects of CT protocol and in-room x-ray technique on CyberKnife (Accuray Inc.) tracking accuracy by evaluating end-to-end tests.

Methods: End-to-end (E2E) tests were performed for the different tracking methods (6D skull, fiducial, spine, and lung) using an anthropomorphic head phantom (Accuray Inc. Read More

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December 2020

RealDRR - Rendering of realistic digitally reconstructed radiographs using locally trained image-to-image translation.

Radiother Oncol 2020 12 8;153:213-219. Epub 2020 Oct 8.

Department of Electronics and Informatics (ETRO), Vrije Universiteit Brussel, Brussels, Belgium; Imec, Leuven, Belgium.

Introduction: Digitally reconstructed radiographs (DRRs) represent valuable patient-specific pre-treatment training data for tumor tracking algorithms. However, using current rendering methods, the similarity of the DRRs to real X-ray images is limited, requires time-consuming measurements and/or are computationally expensive. In this study we present RealDRR, a novel framework for highly realistic and computationally efficient DRR rendering. Read More

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December 2020

Acuros dose verification of ultrasmall lung lesions with EBT-XD film in a homogeneous and heterogeneous anthropomorphic phantom setup.

Med Phys 2020 Nov 7;47(11):5829-5837. Epub 2020 Oct 7.

Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands.

Purpose: Modern type 'c' dose calculation algorithms like Acuros can predict dose for lung tumors larger than approximately 4 cm with a relative uncertainty up to 5%. However, increasingly better tumor diagnostics are leading to the detection of very small early-stage lung tumors that can be treated with stereotactic body radiotherapy (SBRT) for inoperable patients. This raises the question whether dose algorithms like Acuros can still accurately predict dose within 5% for challenging conditions involving small treatment fields. Read More

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November 2020

On the use of AAA and AcurosXB algorithms for three different stereotactic ablative body radiotherapy (SABR) techniques: Volumetric modulated arc therapy (VMAT), intensity modulated radiation therapy (IMRT) and 3D conformal radiotherapy (3D-CRT).

Rep Pract Oncol Radiother 2019 Jul-Aug;24(4):399-408. Epub 2019 Mar 23.

School of Health & Biomedical Sciences, RMIT University, Victoria, Australia.

Aim: The purpose of this study was to investigate the dosimetric characteristics of three stereotactic ablative body radiotherapy (SABR) techniques using the anisotropic analytical algorithm (AAA) and Acuros XB algorithm. The SABR techniques include coplanar volumetric modulated arc therapy (C-VMAT), non-coplanar intensity modulated radiation therapy (NC-IMRT) and non-coplanar three-dimensional conformal radiotherapy (NC-3D CRT).

Background: SABR is a special type of radiotherapy where a high dose of radiation is delivered over a short time. Read More

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A real-time, single-exposure, dual-energy subtraction mask for markerless tumor tracking in radiotherapy: Proof of concept.

Authors:
Shinichiro Mori

Phys Med 2019 Jul 29;63:63-69. Epub 2019 May 29.

Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555, Japan. Electronic address:

Introduction: Bone density can interfere with fluoroscopy-guided tumor tracking in radiotherapy. To improve markerless tumor tracking accuracy, we developed a dual energy subtraction (DES) mechanical image mask to use with a single x-ray exposure.

Methods: The DES mask consists of 2-mm-thick stainless-steel with 128 pairs of slits (0. Read More

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Comparison of five dose calculation algorithms in a heterogeneous media using design of experiment.

Phys Med 2019 May 3;61:103-111. Epub 2019 May 3.

Institut de Cancérologie de l'Ouest, Centre Paul Papin, 49055 Angers, France. Electronic address:

Purpose: Design of experiments (DoE) provides a methodology to reveal the influence of input values on the measured output with a limited number of trials. The purpose of this study was to describe how DoE can be used to evaluate the performances of several dose calculation systems in heterogeneous media, including algorithms like Pencil Beam (PB), Anisotropic Analytical Algorithm (AAA), Acuros XB (AXB), Monte Carlo (MC) and Collapsed Cone Volume (CCV).

Method: This study was carried out using a CIRS Model 002LFC IMRT Thorax Phantom customized with a water-equivalent heterogeneity inside the lung. Read More

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Log file-based dose reconstruction and accumulation for 4D adaptive pencil beam scanned proton therapy in a clinical treatment planning system: Implementation and proof-of-concept.

Med Phys 2019 Mar 4;46(3):1140-1149. Epub 2019 Feb 4.

Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Background And Purpose: Motion-induced uncertainties hamper the clinical implementation of pencil beam scanning proton therapy (PBS-PT). Prospective pretreatment evaluations only provide multiscenario predictions without giving a clear conclusion for the actual treatment. Therefore, in this proof-of-concept study we present a methodology for a fraction-wise retrospective four-dimensional (4D) dose reconstruction and accumulation aiming at the evaluation of treatment quality during and after treatment. Read More

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Multi-institutional evaluation using the end-to-end test for implementation of dynamic techniques of radiation therapy in Thailand.

Rep Pract Oncol Radiother 2019 Jan-Feb;24(1):124-132. Epub 2018 Nov 28.

Division of Radiation Oncology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Aim: In this study, an accuracy survey of intensity-modulated radiation therapy (IMRT) and volumetric arc radiation therapy (VMAT) implementation in radiotherapy centers in Thailand was conducted.

Background: It is well recognized that there is a need for radiotherapy centers to evaluate the accuracy levels of their current practices, and use the related information to identify opportunities for future development.

Materials And Methods: An end-to-end test using a CIRS thorax phantom was carried out at 8 participating centers. Read More

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November 2018

Commissioning an in-room mobile CT for adaptive proton therapy with a compact proton system.

J Appl Clin Med Phys 2018 May 6;19(3):149-158. Epub 2018 Apr 6.

Orlando Health UF Health Cancer Center, Orlando, FL, USA.

Purpose: To describe the commissioning of AIRO mobile CT system (AIRO) for adaptive proton therapy on a compact double scattering proton therapy system.

Methods: A Gammex phantom was scanned with varying plug patterns, table heights, and mAs on a CT simulator (CT Sim) and on the AIRO. AIRO-specific CT-stopping power ratio (SPR) curves were created with a commonly used stoichiometric method using the Gammex phantom. Read More

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Film-based dose validation of Monte Carlo algorithm for Cyberknife system with a CIRS thorax phantom.

J Appl Clin Med Phys 2018 May 30;19(3):142-148. Epub 2018 Mar 30.

Department of Radiation Oncology, Peking University Third Hospital, Beijing, China.

Monte Carlo (MC) simulation, as the most accurate dose calculation algorithm, is available in the MultiPlan treatment planning system for Cyberknife. The main purpose of this work was to perform experiments to thoroughly investigate the accuracy of the MC dose calculation algorithm. Besides the basic MC beam commissioning, two test scenarios were designed. Read More

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Determination of the effective dose delivered by image guided radiotherapy in head & neck and breast treatments.

Z Med Phys 2018 Dec 6;28(4):276-285. Epub 2018 Feb 6.

Institute of Radiation Physics, Lausanne University Hospital, Lausanne, Switzerland. Electronic address:

Purpose: Image guided radiotherapy (IGRT) improves patient positioning for treatment delivery at the cost of an additional dose. This work aimed to calculate the effective dose (as an indicator of dose) for head & neck (H&N) and breast IGRT treatments by implementing dose calculation models to determine the dose distributions.

Methods: The kV dose-models were created for the IGRT systems of Elekta Synergy (XVI) and Varian Clinac (OBI) linear accelerators within Philips Pinnacle TPS. Read More

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December 2018

Evaluation of dose calculation accuracy of various algorithms in lung equivalent inhomogeneity: Comparison of calculated data with Gafchromic film measured results.

J Cancer Res Ther 2017 Oct-Dec;13(6):1007-1014

Department of Radiotherapy, King George Medical University UP, Lucknow, Uttart Pradesh, India.

Aim: To evaluate dose calculation accuracy of various algorithms in lung equivalent inhomogeneity comprising tumor within it and comparison with Gafchromic film data.

Materials And Methods: Gafchromic film measured central axis absorbed dose in lung insert (-700 Hounsfield unit [HU]), in racemosa wood cylindrical inhomogeneity (-725 HU) and at three surfaces of tumor (-20 HU) created in cylindrical inhomogeneity, put in the cavity of computerized imaging reference systems (CIRS) thorax phantom were compared with convolution (CON), superposition (SP), fast SP (FSP), and X-ray voxel Monte Carlo (XVMC) algorithms calculated dose using 6 MV beams of field size 2 cm × 2 cm, 3 cm × 3 cm, 4 cm × 4 cm, 5 cm × 5 cm, and 8 cm × 8 cm.

Results: XVMC was in good agreement with film measured results for all selected field sizes except 3 cm × 3 cm. Read More

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Reducing 4DCBCT imaging time and dose: the first implementation of variable gantry speed 4DCBCT on a linear accelerator.

Phys Med Biol 2017 06 5;62(11):4300-4317. Epub 2017 May 5.

Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, NSW 2006, Australia.

Four dimensional cone beam computed tomography (4DCBCT) uses a constant gantry speed and imaging frequency that are independent of the patient's breathing rate. Using a technique called respiratory motion guided 4DCBCT (RMG-4DCBCT), we have previously demonstrated that by varying the gantry speed and imaging frequency, in response to changes in the patient's real-time respiratory signal, the imaging dose can be reduced by 50-70%. RMG-4DCBCT optimally computes a patient specific gantry trajectory to eliminate streaking artefacts and projection clustering that is inherent in 4DCBCT imaging. Read More

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Evaluation of gantry speed on image quality and imaging dose for 4D cone-beam CT acquisition.

Radiat Oncol 2016 Jul 29;11:98. Epub 2016 Jul 29.

Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, 48202, USA.

Background: This study investigates the effect of gantry speed on 4DCBCT image quality and dose for the Varian On-Board Imager®.

Methods: A thoracic 4DCBCT protocol was designed using a 125 kVp spectrum. Image quality parameters were evaluated for 4DCBCT acquisition using Catphan® phantom with real-time position management™ system for gantry speeds varying between 1. Read More

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The first implementation of respiratory triggered 4DCBCT on a linear accelerator.

Phys Med Biol 2016 May 7;61(9):3488-99. Epub 2016 Apr 7.

Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, NSW 2006, Australia.

Four dimensional cone beam computed tomography (4DCBCT) is an image guidance strategy used for patient positioning in radiotherapy. In conventional implementations of 4DCBCT, a constant gantry speed and a constant projection pulse rate are used. Unfortunately, this leads to higher imaging doses than are necessary because a large number of redundant projections are acquired. Read More

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Sleep-disordered breathing and daytime postural stability.

Thorax 2016 06 18;71(6):543-8. Epub 2016 Feb 18.

Center for Investigation and Research in Sleep (CIRS), University Hospital of Lausanne (CHUV), Lausanne, Switzerland.

Objective: Postural stability depends on the coordination of the central nervous system with visual sense, proprioceptive and vestibular information. Sleep deprivation has been shown to affect this function. The objective of our study was to assess the effects of sleep-disordered breathing (SDB) on postural stability. Read More

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Scoring criteria for portable monitor recordings: a comparison of four hypopnoea definitions in a population-based cohort.

Thorax 2015 Nov 20;70(11):1047-53. Epub 2015 Aug 20.

Centre for Investigation and Research in Sleep (CIRS), Lausanne University Hospital (CHUV), Lausanne, Switzerland Pulmonary Department (CHUV), Lausanne University Hospital, Lausanne, Vaud, Switzerland.

Rationale: Limited-channel portable monitors (PMs) are increasingly used as an alternative to polysomnography (PSG) for the diagnosis of obstructive sleep apnoea (OSA). However, recommendations for the scoring of PM recordings are still lacking. Pulse-wave amplitude (PWA) drops, considered as surrogates for EEG arousals, may increase the detection sensitivity for respiratory events in PM recordings. Read More

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November 2015

Adaptation requirements due to anatomical changes in free-breathing and deep-inspiration breath-hold for standard and dose-escalated radiotherapy of lung cancer patients.

Acta Oncol 2015 24;54(9):1453-60. Epub 2015 Jul 24.

b Department of Oncology , Radiotherapy Research Unit, Herlev Hospital, University of Copenhagen , Herlev , Denmark.

Background: Radiotherapy of lung cancer patients is subject to uncertainties related to heterogeneities, anatomical changes and breathing motion. Use of deep-inspiration breath-hold (DIBH) can reduce the treated volume, potentially enabling dose-escalated (DE) treatments. This study was designed to investigate the need for adaptation due to anatomical changes, for both standard (ST) and DE plans in free-breathing (FB) and DIBH. Read More

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January 2016

[Effect of respiratory movement on cone beam computed tomography images].

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 2014 Apr;31(2):314-8

To investigate the impact of respiratory movement to determine the target volume on cone beam CT (CBCT) for lung tumor, we used CIRS dynamic thorax phantom (Model-CIRS008) to simulate the sinusoidal motion of lung tumor. With a constant amplitude, the ratio of the time of near-end-expiratory and near-end-inspiratory (E/I) changed when it was scanned with CBCT. We analyzed the contrast changes of target by extracting the CT value of each pixel on the center line of the target movement direction. Read More

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A further investigation of the centroid-to-centroid method for stereotactic lung radiotherapy: a phantom study.

Med Phys 2013 Oct;40(10):101704

Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, Florida 32610.

Purpose: Our previous study [B. Lu et al., "A patient alignment solution for lung SBRT setups based on a deformable registration technique," Med. Read More

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October 2013

Treatment planning systems dosimetry auditing project in Portugal.

Phys Med 2014 Feb 23;30(1):96-103. Epub 2013 Apr 23.

International Atomic Energy Agency, Vienna, Austria.

Background And Purpose: The Medical Physics Division of the Portuguese Physics Society (DFM_SPF) in collaboration with the IAEA, carried out a national auditing project in radiotherapy, between September 2011 and April 2012. The objective of this audit was to ensure the optimal usage of treatment planning systems. The national results are presented in this paper. Read More

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February 2014

Monte Carlo optimization of total body irradiation in a phantom and patient geometry.

Phys Med Biol 2013 Apr 21;58(8):2461-9. Epub 2013 Mar 21.

Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg, Sweden.

The objective of this work is to apply a Monte Carlo (MC) accelerator model, validated by experimental data at isocentre distances, to a large-field total body irradiation (TBI) technique and to develop a strategy for individual patient treatment on the basis of MC dose distributions. Calculations are carried out using BEAMnrc/DOSXYZnrc code packages for a 15 MV Varian accelerator. Acceptable agreement is obtained between MC data and measurements in a large water phantom behind a spoiler at source-skin distances (SSD) = 460 cm as well as in a CIRS® thorax phantom. Read More

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Localization of deformable tumors from short-arc projections using Bayesian estimation.

Med Phys 2012 Dec;39(12):7205-14

Department of Radiation Oncology, Regensburg University Medical Center, Regensburg, Germany.

Purpose: The authors present a stochastic framework for radiotherapy patient positioning directly utilizing radiographic projections. This framework is developed to be robust against anatomical nonrigid deformations and to cope with challenging imaging scenarios, involving only a few cone beam CT projections from short arcs.

Methods: Specifically, a Bayesian estimator (BE) is explicitly derived for the given scanning geometry. Read More

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December 2012

Poster - Thur Eve - 68: Evaluation and analytical comparison of different 2D and 3D treatment planning systems using dosimetry in anthropomorphic phantom.

Med Phys 2012 Jul;39(7Part4):4637-4638

Cancer Institute of Imam Khomeini hospital.

Purpose: The aim of this study was to evaluate and analytically compare different calculation algorithms applied in our country radiotherapy centers base on the methodology developed by IAEA for treatment planning systems (TPS) commissioning (IAEA TEC-DOC 1583).

Material & Methods: Thorax anthropomorphic phantom (002LFC CIRS inc.), was used to measure 7 tests that simulate the whole chain of external beam TPS. Read More

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SU-E-J-209: A Simple Method to Minimize Uncertainty in ITV Delineation: Phantom Verification.

Med Phys 2012 Jun;39(6Part9):3700-3701

Duke University, Durham, NC.

Purpose: Irregular breathing causes variation in delineation of internal target volume (ITV), which is typically generated in the maximum intensity projection (MIP) images [1]. Previous studies have shown that MIP-based ITV can underestimate true tumor range [2]. This study examines a simple method to reduce such errors by combining the GTV of 3D-CT with the ITV of MIP. Read More

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SU-E-J-137: A Theoretical Model for the Analysis of Residual Motion Artifacts in 4D CT Scans.

Med Phys 2012 Jun;39(6Part8):3684

The Catholic University of Korea.

Purpose: The purpose of this study was to analysis the residual motion artifact in 4D-CT scan using a simple one-dimension theoretical model.

Methods: In order to evaluate the target displacement at each phase image, We used phantom (Dynamic Thorax Phantom, CIRS, Norfolk, VA) which could control programmable regular 1D sine motion and belt type respiratory monitoring system. 2cm diameter spherical target was inserted in the phantom and then we set-up regular 1D sine motion and adjusted three level of amplitude (10, 20, 30 mm) with fixed period (4s). Read More

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