560 results match your criteria flattening filter-free


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

Small field measurement and monte carlo model validation of a novel image-guided radiotherapy system.

Med Phys 2021 Oct 10. Epub 2021 Oct 10.

Department of Radiation Oncology, School of Medicine, Stanford University, Stanford, CA, 94304, United States of America.

Purpose: The RefleXion X1 is a novel radiotherapy system that is designed for image-guided radiotherapy and, eventually, biology-guided radiotherapy (BgRT). BgRT is a treatment paradigm that tracks tumor motion using real-time positron emission signals. This study reports the small field measurement results and the validation of a Monte Carlo (MC) model of the first clinical RefleXion unit. Read More

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October 2021

Towards magnetic-field-modulated radiotherapy (MagMRT) with an MR-LINAC-a Monte Carlo study.

Phys Med Biol 2021 Oct 14;66(20). Epub 2021 Oct 14.

Department of Clinical Oncology, Prince of Wales Hospital, Hong Kong SAR, People's Republic of China.

The feasibility of magnetic-field-modulated radiotherapy (MagMRT) with an MR-LINAC was investigated by studying the effects of dose enhancement and reduction using a transverse magnetic field with a longitudinal gradient applied along a photon radiation beam.Geant4 simulation toolkit was used to perform Monte Carlo simulations on a water phantom with the energy spectrum of a 7 MV flattening-filter-free photon beam from an Elekta Unity system as the source of radiation. Linear magnetic field gradients with magnitudes ranged from 1 to 6 T cmand spatial extents of 1-3 cm were used to study the dependence of dose modulation on these two parameters. Read More

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October 2021

Feasibility of operating a millimeter-scale graphite calorimeter for absolute dosimetry of small-field photon beams in the clinic.

Med Phys 2021 Sep 22. Epub 2021 Sep 22.

Medical Physics Unit, Gerald Bronfman Department of Oncology, McGill University, Montreal, Quebec, Canada.

Purpose: To characterize and build a cylindrically layered graphite calorimeter the size of a thimble ionization chamber for absolute dosimetry of small fields. This detector has been designed in a familiar probe format to facilitate integration into the clinical workflow. The feasibility of operating this absorbed dose calorimeter in quasi-adiabatic mode is assessed for high-energy accelerator-based photon beams. Read More

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September 2021

Markerless 3D tumor tracking during single-fraction free-breathing 10MV flattening-filter-free stereotactic lung radiotherapy.

Radiother Oncol 2021 Sep 21;164:6-12. Epub 2021 Sep 21.

Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, the Netherlands.

Background And Purpose: Positional verification during single fraction lung SBRT could increase confidence and reduce the chance of geographic miss. As planar 2DkV imaging during VMAT irradiation is already available on current linear accelerators, markerless tracking based on these images could offer widely available and low-cost verification. We evaluated treatment delivery data and template matching and triangulation for 3D-positional verification during free-breathing, single fraction (34 Gy), 10 MV flattening-filter-free VMAT lung SBRT. Read More

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September 2021

Comparison of calculation algorithms to predict the IQM detector response for various modulation degrees of VMAT treatment plans on linear accelerator equipped with the HD120 MLC.

Med Phys 2021 Sep 9. Epub 2021 Sep 9.

Medical Physics Department, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland.

Purpose: The calculation model for the integral quality monitor (IQM) system does not take into account the characteristics of the HD120 multileaf collimator (MLC), which some Varian accelerators are equipped with. Some treatment plans prepared with this collimator are characterized by a high level of modulation. The aim of the work was to prepare a model for that collimator and to determine the influence of modulation on results of the verification carried out with the use of IQM system. Read More

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September 2021

Verification of Surface Dose for Flattening Filter and Flattening Filter Free Beams in Beam-Matched Medical Linear Accelerators.

Asian Pac J Cancer Prev 2021 Aug 1;22(8):2577-2585. Epub 2021 Aug 1.

Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, India.

Background: The purpose of this study was to evaluate the surface dose (SD) of 6 and 10 MV flattening filter beam (FF) and flattening filter free (FFF) beam for different square field sizes in three Beam-matched medical linear accelerators using a parallel-plate ionization chamber.

Materials And Methods: The experiment was carried out in a phantom composed of 40×40 cm2 solid Water slabs of varying thickness. Further sheets of solid water phantom were added to take readings in the build-up region for both SSD and SAD technique. Read More

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Comparison of whole breast dosimetry techniques - From 3DCRT to VMAT and the impact on heart and surrounding tissues.

J Med Radiat Sci 2021 Aug 25. Epub 2021 Aug 25.

Radiation Oncology Department, Princess Alexandra Hospital, Cancer Services, Brisbane, Queensland, Australia.

Introduction: Various techniques for whole breast radiation therapy (WBRT) have been reported to increase dose to contralateral tissues. Heart dose is of critical importance as there is no apparent dose threshold below which there is no risk. The aim of this study was to compare planning techniques for WBRT that achieves the best target dosimetry and lowest organ at risk (OAR) dose. Read More

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Evidence-Based Planning Target Volume Margin Reduction for Modern Lung Stereotactic Ablative Radiation Therapy Using Deformable Registration.

Adv Radiat Oncol 2021 Nov-Dec;6(6):100750. Epub 2021 Jul 3.

BC Cancer-Prince George, Prince George, British Columbia, Canada.

Purpose: Standard planning target volume (PTV) margins for lung stereotactic ablative radiation therapy (SABR) are 5 mm. High-dose-rate volumetric modulated arc therapy delivered using flattening filter-free (FFF) beams with modern immobilization systems may allow for PTV margin reduction. This study assesses whether PTV margins can be reduced from 5 to 3 mm. Read More

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Comparison between flattening filter-free (FFF) and flattened photon beam VMAT plans for the whole brain radiotherapy (WBRT) with hippocampus sparing.

Asia Pac J Clin Oncol 2021 Jul 31. Epub 2021 Jul 31.

Department of Radiation oncology, The First Hospital of China Medical University, Shenyang, China.

Purpose: To evaluate and investigate the feasibility of flattening filter-free (FFF) beam for the whole-brain radiotherapy (WBRT) with hippocampus sparing.

Methods: Eighteen patients with volumetric-modulated arc therapy (VMAT) plans in FFF and conventional beam modes were included in this study. The prescribed dose was 30 Gy in 10 fractions. Read More

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Out-of-field dose in stereotactic radiotherapy for paediatric patients.

Phys Imaging Radiat Oncol 2021 Jul 4;19:1-5. Epub 2021 Jun 4.

RMIT University, School of Science, Melbourne, Australia.

Background And Purpose: Stereotactic radiotherapy combines image guidance and high precision delivery with small fields to deliver high doses per fraction in short treatment courses. In preparation for extension of these treatment techniques to paediatric patients we characterised and compared doses out-of-field in a paediatric anthropomorphic phantom for small flattened and flattening filter free (FFF) photon beams.

Method And Materials: Dose measurements were taken in several organs and structures outside the primary field in an anthropomorphic phantom of a 5 year old child (CIRS) using thermoluminescence dosimetry (LiF:Mg,Cu,P). Read More

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Calculated relative biological effectiveness (RBE) for initial DNA double-strand breaks (DSB) from flattening filter and flattening filter-free 6 MV X-ray fields.

BJR Open 2021 5;3(1):20200072. Epub 2021 Jul 5.

Department of Radiation Oncology, Niigata Neurosurgical Hospital, Niigata, 3057 Yamada, Nishi-ku, Niigata, Japan.

Objectives: We evaluated the radiobiological effectiveness based on the yields of DNA double-strand breaks (DSBs) of field induction with flattening filter (FF) and FF-free (FFF) photon beams.

Methods: We used the particle and heavy ion transport system (PHITS) and a water equivalent phantom (30 × 30 × 30 cm) to calculate the physical qualities of the dose-mean lineal energy (y) with 6 MV FF and FFF. The relative biological effectiveness based on the yields of DNA-DSBs (RBE) was calculated for standard radiation such as 220 kVp X-rays by using the estimating yields of SSBs and DSBs. Read More

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Quantification of image quality of intra-fractional cone-beam computed tomography for arc irradiation with various imaging condition.

Rep Pract Oncol Radiother 2021 9;26(3):495-501. Epub 2021 Jun 9.

Department of Radiology, University of Yamanashi, Yamanashi, Japan.

Background: 3-dimensional intra-cone beam computed tomography (intra-CBCT ) could be a potentially powerful tool for use with arc irradiation such as volumetric modulated arc therapy. The aim of the study was to evaluate the image quality of intra-cone beam computed tomography (intra-CBCT ) for arc irradiation with various imaging condition.

Materials And Methods: Two types of intra-CBCT imaging techniques were evaluated - intra-fractional CBCT with flattening filtered (FF) beam (intra-FF CBCT ) and that with flattening filter free (FFF) beam (intra-FFF CBCT ). Read More

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Comparison of 2 dynamic conformal arc plans based on high-dose rate flattening filter free beams for peripheral lung cancer.

Zhong Nan Da Xue Xue Bao Yi Xue Ban 2021 Jun;46(6):615-619

Department of Radiation Therapy, Cancer Hospital of Shantou University Medical College, Shantou Guangdong 515000, China.

Objectives: To compare 2 dynamic conformal arc plans based on the high dose rate flattening filter free (FFF) beams, and to evaluate the dosimetric differences.

Methods: A total of 20 patients with early peripheral non-small cell lung cancer were selected, and 2 dynamic conformal arc plans were designed in the Eclipse 10.0 treatment planning system (TPS). Read More

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Linac-based STereotactic Arrhythmia Radioablation (STAR) for ventricular tachycardia: a treatment planning study.

Jpn J Radiol 2021 Jul 9. Epub 2021 Jul 9.

Radiation Oncology Department, General Regional Hospital "F. Miulli", Acquaviva delle Fonti, Bari, Italy.

Object: To analyze geometrical approaches, prescription modalities, and delivery efficiency for linear accelerator (Linac)-based STereotactic Arrhythmia Radioablation (STAR) for ventricular tachycardia.

Methods: The anatomy and planning target volume (PTV) of the first Italian STAR patient were used. To assess geometrical approaches, 3 plans prescribed to 75% isodose-line, differing for number, length of arcs, and couch rotations, were generated and compared (Plans#1-3). Read More

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Medical X-band linear accelerator for high-precision radiotherapy.

Med Phys 2021 Sep 28;48(9):5327-5342. Epub 2021 Jul 28.

Advanced Institute for Radiation Fusion Medical Technology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.

Purpose: Recently, high-precision radiotherapy systems have been developed by integrating computerized tomography or magnetic resonance imaging to enhance the precision of radiotherapy. For integration with additional imaging systems in a limited space, miniaturization and weight reduction of the linear accelerator (linac) system have become important. The aim of this work is to develop a compact medical linac based on 9. Read More

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September 2021

Dose response of a radiophotoluminescent glass dosimeter for TomoTherapy, CyberKnife, and flattening-filter-free linear accelerator output measurements in dosimetry audit.

Phys Med 2021 Aug 29;88:91-97. Epub 2021 Jun 29.

QST Hospital, National Institutes for Quantum and Radiological Science and Technology, Japan.

Purpose: We experimentally determined the radiophotoluminescent glass dosimeter (RPLD) dose responses for TomoTherapy, CyberKnife, and flattening-filter-free (FFF) linear accelerator (linac) outputs for dosimetry audits in Japan.

Methods: A custom-made solid phantom with a narrow central-axis spacing of three RPLD elements was used for output measurement to minimise the dose-gradient effect of the non-flattening filter beams. For RPLD dose estimation, we used the ISO 22127 formalism. Read More

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Reducing variability among treatment machines using knowledge-based planning for head and neck, pancreatic, and rectal cancer.

J Appl Clin Med Phys 2021 Jul 20;22(7):245-254. Epub 2021 Jun 20.

Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Purpose: This study aimed to assess dosimetric indices of RapidPlan model-based plans for different energies (6, 8, 10, and 15 MV; 6- and 10-MV flattening filter-free), multileaf collimator (MLC) types (Millennium 120, High Definition 120, dual-layer MLC), and disease sites (head and neck, pancreatic, and rectal cancer) and compare these parameters with those of clinical plans.

Methods: RapidPlan models in the Eclipse version 15.6 were used with the data of 28, 42, and 20 patients with head and neck, pancreatic, and rectal cancer, respectively. Read More

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Dosimetric verification of stereotactic body radiotherapy treatment plan via ArcCHECK-3DVH system.

Zhong Nan Da Xue Xue Bao Yi Xue Ban 2021 May;46(5):475-480

Department of Oncology, Third Xiangya Hospital, Central South University, Changsha 410013, China.

Objectives: To study the feasibility of ArcCHECK-3DVH system in dosimetric verification for stereotactic body radiaotherapy (SBRT) with flattening filter free (FFF) model.

Methods: SBRT treatment plans for 57 patients were introduced into ArcCHECK phantom and recalculated. The calculated dose distribution of treatment planning system and the measured dose distribution of ArcCHECK phantom were compared by γ analysis. Read More

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Progress and prospects of flattening filter free beam technology in radiosurgery and stereotactic body radiotherapy.

Crit Rev Oncol Hematol 2021 Jul 17;163:103396. Epub 2021 Jun 17.

West University of Timisoara, Faculty of Physics, Timisoara, Romania; Faculty of Informatics & Science, University of Oradea, Oradea, 410087, Romania; Cancer Research Institute, University of South Australia, Adelaide, SA, 5001, Australia. Electronic address:

The aim of this work is to summarize and evaluate the current status of knowledge on flattening filter free (FFF) beams and their applications in stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT). A PubMed search was undertaken in order to identify relevant publications using FFF and stereotactic radiotherapy as keywords. On a clinical aspect, lung tumors treated with FFF SBRT show promising results in terms of local control and overall survival with acute toxicities consistent with those that occur with standard radiotherapy. Read More

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Evaluation of a new foetal shielding device for pregnant brain tumour patients.

Radiat Oncol 2021 Jun 13;16(1):109. Epub 2021 Jun 13.

Department of Radiation Oncology, Seoul National University Bundang Hospital, 82 Gumi-ro 173 Beon-gil, Bundang-gu, Seongnam-si, 13620, Gyeonggi-do, Korea.

Background: The present study aimed to propose a new foetal shielding device for pregnant cancer patients to reduce the foetal dose associated with treatment techniques using multiple gantry angles, such as intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT).

Methods: Three shielding structures were designed to minimise the scattered and leaked radiation from various gantry angles and radiation scattering within the patient. The base-plate part that can be placed on the treatment couch was designed to reduce the scattered and leaked radiation generated at gantry angles located near 180°. Read More

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Markerless Real-Time 3-Dimensional kV Tracking of Lung Tumors During Free Breathing Stereotactic Radiation Therapy.

Adv Radiat Oncol 2021 Jul-Aug;6(4):100705. Epub 2021 Apr 20.

Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, the Netherlands.

Purpose: Accurate verification of tumor position during irradiation could reduce the probability of target miss. We investigated whether a commercial gantry-mounted 2-dimensional (2D) kilo-voltage (kV) imaging system could be used for real-time 3D tumor tracking during volumetric modulated arc therapy (VMAT) lung stereotactic body radiation therapy (SBRT). Markerless tumor tracking on kV fluoroscopic images was validated using a life-like moving thorax phantom and subsequently performed on kV images continuously acquired before and during free-breathing VMAT lung SBRT. Read More

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Operation and calibration of the novel PTW 1600SRS detector for the verification of single isocenter stereotactic radiosurgery treatments of multiple small brain metastases.

Br J Radiol 2021 Jul 11;94(1123):20210473. Epub 2021 Jun 11.

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

Objectives: The aim of this work was to evaluate the operation of the 1600SRS detector and to develop a calibration procedure for verifying the dose delivered by a single isocenter stereotactic radiosurgery (SRS) treatment of small multiple brain metastases (BM).

Methods: 14 clinical treatment cases were selected with the number of BM ranging from 2 to 11. The dosimetric agreement was investigated between the calculated and the measured dose by an OCTAVIUS 1600SRS array detector in an OCTAVIUS 4D phantom equipped with dedicated SRS top. Read More

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Assessment of a conventional volumetric-modulated arc therapy knowledge-based planning model applied to the new Halcyon© O-ring linac in locoregional breast cancer radiotherapy.

Phys Med 2021 Jun 26;86:32-43. Epub 2021 May 26.

Institut Curie, Radiation Oncology Department, 26 rue d'Ulm, Paris 75005, France; Institut Curie, University Paris Saclay, PSL Research University, Inserm LITO, Orsay, France.

Introduction: The aim of this study was to evaluate the performance of a knowledge-based planning (KBP) model for breast cancer trained on plans performed on a conventional linac with 6 MV FF (flattening filter) beams and volumetric-modulated arc therapy (VMAT) for plans performed on the new jawless Halcyon© system with 6 MV FFF (flattening filter-free) beams.

Materials And Methods: Based on the RapidPlan© (RP) KBP optimization engine, a DVH Estimation Model was first trained using 56 VMAT left-sided breast cancer treatment plans performed on a conventional linac, and validated on another 20 similar cases (without manual intervention). To determine the capacity of the model for Halcyon©, an additional cohort of 20 left-sided breast cancer plans was generated with RP and analyzed for both TrueBeam© and Halcyon© machines. Read More

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Time motion study to evaluate the impact of flattening filter free beam on overall treatment time for frameless intracranial radiosurgery using Varian TrueBeam linear accelerator.

Rep Pract Oncol Radiother 2021 25;26(1):111-118. Epub 2021 Feb 25.

Department of Radiation Oncology, Aster Medcity, Kochi, Kerala, India.

Background: The aim was to study the impact of the flattening filter free (FFF) beam on overall treatment time for frameless intracranial radiosurgery using TrueBeam LINAC.The development of frameless stereotactic radiosurgery (SRS) is possible due to the incorporation of image guidance in the delivery of treatment. It is important to analyze the cost and benefits of FFF beams for treating SRS by understanding the impact of FFF beams in reducing the treatment time. Read More

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February 2021

Survey on utilization of flattening filter-free photon beams in Japan.

J Radiat Res 2021 Jul;62(4):726-734

Department of Information Technology and Medical engineering, Human Health Science, Graduate School of Medicine, Kyoto University, 53 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.

To understand the current state of flattening filter-free (FFF) beam implementation in C-arm linear accelerators (LINAC) in Japan, the quality assurance (QA)/quality control (QC) 2018-2019 Committee of the Japan Society of Medical Physics (JSMP) conducted a 37-question survey, designed to investigate facility information and specifications regarding FFF beam adoption and usage. The survey comprised six sections: facility information, devices, clinical usage, standard calibration protocols, modeling for treatment planning (TPS) systems and commissioning and QA/QC. A web-based questionnaire was developed. Read More

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Implantable cardiac pacemaker failure by cumulative dose effects of flattening filter free beams.

J Radiat Res 2021 Jul;62(4):735-739

Department of Radiology, Aichi Medical University Hospital, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195 Japan.

Cumulative dose effects, which are one of the main causes of errors that occur when an implantable cardiac pacemaker (ICP) is irradiated with ionizing radiation, induce permanent failure in ICPs. Although flattening filter free (FFF) beams, which are often used in stereotactic radiotherapy, are known to have different characteristics from conventional (with flattening filter [WFF]) beams, the cumulative dose effects on ICPs with FFF beams have been under-investigated. This study investigates ICP failure induced by cumulative dose effects of FFF beams. Read More

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SBRT treatment of abdominal and pelvic oligometastatic lymph nodes using ring-mounted Halcyon Linac.

J Appl Clin Med Phys 2021 Jun 25;22(6):162-171. Epub 2021 May 25.

Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA.

Purpose/objectives: This work seeks to evaluate the plan quality, treatment delivery efficiency, and accuracy of single-isocenter volumetric modulated arc therapy (VMAT) of abdominal/pelvic oligometastatic lymph nodes (LNs) stereotactic body radiation therapy (SBRT) on Halcyon Linac.

Materials And Methods: After completing the in-house multitarget end-to-end phantom testing and independent dose verification using MD Anderson's single-isocenter/multi-target (lung and spine target inserts) thorax phantom, eight patients with two to three abdominal/pelvic oligometastatic LNs underwent highly conformal single-isocenter VMAT-SBRT treatment using the Halcyon Linac 6MV flattening filter free (FFF) beam. Targets were identified using an Axumin PET/CT scan co-registered with planning CT images and a single-isocenter was placed between/among the targets. Read More

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Is Synchronous Bilateral Breast Irradiation Using Flattening Filter-Free Beam-Based Volumetric-Modulated Arc Therapy Beneficial? A Dosimetric Study.

J Med Phys 2020 Oct-Dec;45(4):226-233. Epub 2021 Feb 2.

Department of Physics, School of Advanced Science, Vellore Institute of Technology, Vellore, Tamil Nadu, India.

Objective: The aim of this study is to validate the clinical use of flattening filter-free (FFF) beam-based volumetric-modulated arc therapy (VMAT) in synchronous bilateral breast carcinoma (SBBC) patient treatments and to compare with flattening filtered (FF) beam-based VMAT.

Materials And Methods: Computed tomography images of 15 SBBC patients were taken for this study. A dose of 50 Gy in 25 fractions was prescribed to planning target volume (PTV). Read More

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February 2021