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Williams C, Seco J, Mishra P, St. James S, Mak R, Berbeco R, Lewis J. SU-E-J-29: Assessing the Dosimetric Effects of Tumor Tracking During Irregular Respiration Using a Mass-Conserving XCAT Phantom. Med Phys 2013. [DOI: 10.1118/1.4814241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Verburg J, Riley K, Seco J. TH-C-144-02: Experimental Study of Discrete Prompt Gamma Lines for In-Vivo Proton Range Verification. Med Phys 2013. [DOI: 10.1118/1.4815796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Hansen DC, Sorensen TS, Seco J. WE-G-141-05: The Image Quality of Ion Computed Tomography at Clinical Imaging Dose Levels. Med Phys 2013. [DOI: 10.1118/1.4815656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Huenemohr N, Paganetti H, Greilich S, Jaekel O, Seco J. TH-C-144-03: Tissue Decomposition From Dual Energy CT Data to Reduce Range Uncertainties in Proton and Carbon Radiotherapy. Med Phys 2013. [DOI: 10.1118/1.4815797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Mishra P, Seco J, Li R, St. James S, Berbeco R, Williams C, Lewis J. TU-E-141-10: 3D Delivered Dose Assessment for SBRT Treatment Based On Estimated Volumetric Time-Varying Images From a Single Projection Image. Med Phys 2013. [DOI: 10.1118/1.4815438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Seco J, Oumano M, Hansen DC. SU-D-500-07: Evaluation of the Spatial Resolution of Proton/carbon Computed Tomography Using Modulation Transfer Function. Med Phys 2013. [DOI: 10.1118/1.4814024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Koybasi O, Lewis J, Mishra P, James S, Seco J. SU-E-T-682: The Dosimetric Consequences of 4DCT-Based Motion Margin Estimation for Proton Radiotherapy. Med Phys 2013. [DOI: 10.1118/1.4815109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Raytchev M, Seco J. SU-D-134-01: 3D Proton Radiography of Simple Inhomogeneities: Implications for Tumor Depth Tracking. Med Phys 2013. [DOI: 10.1118/1.4814046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Seco J, Reza H, Oh K, Doppke K, Spadea M. Stereotactic Body Radiation Therapy (SBRT) of Spine Lesions: Optimizing Number of IMRT Beams and Monte Carlo Assessment of Dose Predictions. Int J Radiat Oncol Biol Phys 2012. [DOI: 10.1016/j.ijrobp.2012.07.2195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Seco J, Harb N, Chen W, Simeone F, Yock T, Kooy H, Delaney T, MacDonald S. Decreased Vertebral Column Dose in Spinal Irradiation With IMPT and Proton Arc Techniques: Potential for Protons to Allow for CSI Without Inducing Spinal Growth Impairment. Int J Radiat Oncol Biol Phys 2012. [DOI: 10.1016/j.ijrobp.2012.07.2234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Spadea M, Fassi A, Depauw N, Riboldi M, Baroni G, Seco J. Contrast Enhanced Proton Radiography for In-room Soft Tissue-based Setup. Int J Radiat Oncol Biol Phys 2012. [DOI: 10.1016/j.ijrobp.2012.07.346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Spadea M, Fassi A, Depauw N, Riboldi M, Baroni G, Seco J. TH-E-BRA-05: Improving the Contrast of Proton and Carbon Radiography by Using CT Prior Knowledge. Med Phys 2012. [DOI: 10.1118/1.4736366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Raytchev M, Safai S, Seco J. SU-E-I-111: Evaluation of the Analytical Scattering Models of 1) Lynch-Dahl 2) Highland and 3) Rossi for Proton Beams and Comparison with GEANT4 Monte Carlo Simulations as a Prerequisite for Proton Radiography Applications for Patients. Med Phys 2012; 39:3650. [PMID: 28517669 DOI: 10.1118/1.4734828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To evaluate the approximate 1) Lynch-Dahl 2) Highland and 3) Rossi scattering models for proton beams with GEANT4 Monte Carlo. This is a prerequisite for proton radiography applications for patients. METHODS A Matlab program developed in-house at MGH was used to obtain a semianalytical generalized Fermi-Eyges theory estimation of the spatial and angular spreads of a 230 MeV zero-spread incident proton beam as a function of depth. The constants of 1) Lynch-Dahl 2) Highland and 3) Rossi were used respectively for each model. MC simulations will determine which approximation provides the best prediction for different media configurations. Further, the calculated spreads were used to inform proton radiography imaging by calculating two limiting angles, a positional Acut and a directional Ccut. Acut is defined as the viewing angle of a point of incidence observer at which they see a point displaced by one positional standard deviation. Ccut is defined as the direction cosine of one angular standard deviation momenta. RESULTS Both the angular and spatial spreads as well as their respective model differences rose monotonically with depth in water. At 30 cm depth the angular spread reached values around 3 degrees with about 0.32 degrees model difference, translating to Ccut differences in the first or second significant digit. At the same depth the spatial spread reached values around 1.2 cm with about 0.7 mm model difference, translating to Acut differences in the first or second significant digit. Preliminary MC data (not shown) indicate that the signals obtained due to the influence of inhomogeneities are small and the model differences may be relevant. CONCLUSIONS We observed non-negligible differences between the models using MC. Further analysis is required to understand, which model provides most accurate scattering predictions for protons penetrating different media configurations.
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Depauw N, Seco J. TH-A-213CD-09: The Use of Scintillating Fibers for Proton Imaging Purposes. Med Phys 2012. [DOI: 10.1118/1.4736539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Goulet M, Gingras L, Depauw N, Archambault L, Seco J, Beaulieu L. WE-G-BRB-06: Real-Time Radiation Field Tracking Using Long Scintillating Fibers. Med Phys 2012; 39:3968. [DOI: 10.1118/1.4736192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Verburg J, Shih H, Seco J. MO-A-213AB-06: Validation of Nuclear Reaction Models to Simulate Proton Therapy Range Verification Using Prompt Gamma-Rays. Med Phys 2012; 39:3860. [DOI: 10.1118/1.4735758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Seco J, Oumano M, Depauw N, Dias M, Teixeira R. SU-E-I-97: Characterizing the Modulation Transfer Function (MTF) of Proton Radiography. Med Phys 2012; 39:3647. [PMID: 28517648 DOI: 10.1118/1.4734814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To characterize the modulation transfer function (MTF) of proton radiography using GEANT4 Monte Carlo simulations. METHODS A phantom was specifically modeled using five main materials: bone (1.92 g/cm3 ), muscle (1.2 g/cm3 ), water (1.0 g/cm3 ), adipose tissue (0.9 g/cm3 ), and lung (0.3 g/cm3 ). The basic geometry of the phantom consists of cube-shaped inserts of biological materials placed in water. The thickness of the water, the size of the cube, the depth of the cube in the water, and the proton beam energy have all been varied and studied. The contrast-to-noise ratio (CNR) between the two materials was evaluated at multiple points along a line-of-interest (LOI) in order to ultimately characterize the spatial resolution by the 10% point of the modulation-transfer-function (MTF10% or MTF 10). RESULTS The MTF was generated for interfaces of water-lung, water-bone, water-muscle, water-adipose. This study indicates that proton radiography can distinguish one material from another with a resolution better than 1 mm for water-adipose and water-muscle or sub-millimeter in cases of water-bone and water-lung interfaces. CONCLUSIONS The sub-millimeter resolution of proton radiography offers clinicians a potentially tool in specific tumor diagnostics (such as in lung cancer), patient-setup for daily proton therapy, and the reduction of absorbed dose delivered when compared to photon imaging.
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Richter C, Andronesi OC, Yuan Y, Bortfeld T, Guimaraes AR, Hong TS, Seco J. TH-E-218-08: In-Vivo Dosimetric Verification of Hypo-Fractionated Proton Radiation Therapy of the Liver with Hepatocyte-Specific Functional MRI. Med Phys 2012. [DOI: 10.1118/1.4736394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Bortfeld T, Craft D, Chen W, Trofimov A, Richter C, Seco J, Ramakrishnan J, Unkelbach J. SP-0021 TREATMENT PLANNING: INTEGRATING ROBUSTNESS IN OPTIMIZATION. Radiother Oncol 2012. [DOI: 10.1016/s0167-8140(12)70360-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Roberts DA, Hansen VN, Thompson MG, Poludniowski G, Niven A, Seco J, Evans PM. Kilovoltage energy imaging with a radiotherapy linac with a continuously variable energy range. Med Phys 2012; 39:1218-26. [DOI: 10.1118/1.3681011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Tsiamas P, Seco J, Han Z, Bhagwat M, Maddox J, Kappas C, Theodorou K, Makrigiorgos M, Marcus K, Zygmanski P. A modification of flattening filter free linac for IMRT. Med Phys 2011; 38:2342-52. [PMID: 21776768 DOI: 10.1118/1.3571419] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE This study investigates the benefits of a modified flattening filter free (FFF) linac over the standard (STD) linac equipped with the flattening filter. Energy and angular spread of the electron beam of the FFF linac were modified. Modification of FFF beam parameters is explored to maximize the monitor unit efficiency and to minimize the head scatter in IMRT delivery for large target volumes or targets lying away from the central axis. METHODS The EGSnrc code is used to model FFF and STD linacs and study basic beam properties for both linac types in various beam configurations. Increasing energy of FFF linac results in similar beam attenuation properties and maximized dose rate compared to STD linac. Matching beam attenuation properties allows a more direct exploration of beam flatness of FFF linac in regard to IMRT delivery, especially away from the central axis where the effective dose rate is considerably smaller than the one at the central axis. Flatness of open beam dose profile of FFF linac is improved by increasing the angular spread of the electron beam. The resulting dose rate within the treatment field and outside of the field (peripheral dose) are characterized and compared to the unmodified FFF and STD linacs, RESULTS In order to match beam penetration properties, the energy of FFF is adjusted from 6.5 to 8.0 MeV for small to medium field sizes and from 6.5 to 8.5 MeV for larger ones. Dose rate of FFF vs STD linac increased by a factor of 1.9 (6.5 MeV) and 3.4-4.1 (8.0-8.5 MeV). Adjusting the mean angular spread of the electron beam from 0 degrees to 5 degrees-10 degrees resulted in complete flattening of photon beam for field sizes between 10 x 10 cm2 and 15 x 15 cm2 and partial flattening for field sizes from 15 x 15 cm2 to 30 x 30 cm2. Values of angular spread > or =14 degrees are not recommended as they exceed the opening of the primary collimator, affecting the area at the edges of the field. FFF fields of sizes smaller than 6 x 6 cm2 are already flat and beam flattening is not necessary. Overall, the angular spread of 5 degrees-10 degrees is sufficient and can satisfactorily flatten open beam dose profiles even for larger field sizes. Increasing the electron beam angular spread amounts to a slight decrease of dose rate of FFF linac. However, for angular spread, 5 degrees-10 degrees dose rate factor of FFF vs STD is still about 1.6-2.6, depending on the field size (and the adjusted energy). Similarly, in case of peripheral dose, a moderate increase in dose can be observed for angular spread of 5 degrees-10 degrees and for field sizes 10 x 10 cm2 to 30 x 30 cm2. Lastly, beam flatness of not modified FFF linac can be conveniently described by an analytical function representing a ratio of STD vs FFF doses: 1 + b|r|(n). CONCLUSIONS A modified FFF beamline with increased energy and electron beam angular spread results in satisfactory flattened beam and high dose rate within the field. Peripheral dose remaining at similar (or smaller) level than that of STD linac for the same delivered dose within the treatment field.
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Roberts DA, Hansen VN, Thompson MG, Poludniowski G, Niven A, Seco J, Evans PM. Comparative study of a low-Z cone-beam computed tomography system. Phys Med Biol 2011; 56:4453-64. [PMID: 21719950 DOI: 10.1088/0031-9155/56/14/014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Computed tomography images have been acquired using an experimental (low atomic number (Z) insert) megavoltage cone-beam imaging system. These images have been compared with standard megavoltage and kilovoltage imaging systems. The experimental system requires a simple modification to the 4 MeV electron beam from an Elekta Precise linac. Low-energy photons are produced in the standard medium-Z electron window and a low-Z carbon electron absorber located after the window. The carbon electron absorber produces photons as well as ensuring that all remaining electrons from the source are removed. A detector sensitive to diagnostic x-ray energies is also employed. Quantitative assessment of cone-beam computed tomography (CBCT) contrast shows that the low-Z imaging system is an order of magnitude or more superior to a standard 6 MV imaging system. CBCT data with the same contrast-to-noise ratio as a kilovoltage imaging system (0.15 cGy) can be obtained in doses of 11 and 244 cGy for the experimental and standard 6 MV systems, respectively. Whilst these doses are high for everyday imaging, qualitative images indicate that kilovoltage like images suitable for patient positioning can be acquired in radiation doses of 1-8 cGy with the experimental low-Z system.
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Yuan Y, Andronesi O, Bortfeld T, Guimaraes A, Hong T, Seco J. TU-A-BRC-09: Feasibility Study of MRI in Assessing in Vivo Proton End-Of-Range for Liver Cancer. Med Phys 2011. [DOI: 10.1118/1.3613085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Seco J, Dias M, Depauw N, MacDonald S. SU-E-J-168: Proton Radiography for Pediatric, T-Spine and Lung Malignancies; Development and Enhancement of a Proton Imaging Technique. Med Phys 2011. [DOI: 10.1118/1.3611936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Verburg J, Seco J. SU-E-I-34: CT Metal Artifact Reduction in Clinical Perspective: Novel Methods Tailored to Specific Implants. Med Phys 2011. [DOI: 10.1118/1.3611607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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