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Ma P, Tian Y, Li M, Niu C, Song Y, Dai J. Delivery of intensity-modulated electron therapy by mechanical scanning: An algorithm study. Front Oncol 2022; 12:1063577. [PMID: 36505866 PMCID: PMC9730234 DOI: 10.3389/fonc.2022.1063577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 11/07/2022] [Indexed: 11/27/2022] Open
Abstract
Purpose In principle, intensity-modulated electron therapy (IMET) can be delivered through mechanical scanning, with a robotic arm mounting a linac. Materials and methods Here is a scanning algorithm to identify the back-and-forth, top-to-bottom (zigzag) pattern scan sequence. The algorithm includes generating beam positions with a uniform resolution according to the applicator size; adopting discrete energies to achieve the depth of 90% dose by compositing energies; selecting energy by locating the target's distal edge; and employing the energy-by-energy scan strategy for step-and-shoot discrete scanning. After a zigzag scan sequence is obtained, the delivery order of the scan spots is optimized by fast simulated annealing (FSA) to minimize the path length. For algorithm evaluation, scan sequences were generated using the computed tomography data of 10 patients with pancreatic cancer undergoing intraoperative radiotherapy, and the results were compared between the zigzag path and an optimized path. A simple calculation of the treatment delivery time, which comprises the irradiation time, the total robotic arm moving time, the time for energy switch, and the time to stop and restart the beam, was also made. Results In these clinical cases, FSA optimization shortened the path lengths by 12%-43%. Assuming the prescribed dose was 15 Gy, machine dose rate was 15 Gy/s, energy switch time was 2 s, stop and restart beam time was 20 ms, and robotic arm move speed was 50 mm/s, the average delivery time was 124±38 s. The largest reduction in path length yielded an approximately 10% reduction in the delivery time, which can be further reduced by increasing the machine dose rate and the robotic arm speed, decreasing the time for energy switch, and/or developing more efficient algorithms. Conclusion Mechanically scanning IMET is potentially feasible and worthy of further exploration.
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Ryu D, Kim JI, Lee S, Ye SJ, Park JM. Remote afterloading patient-specific brachytherapy with liquid radioisotope for irradiation of extensive scalp lesions: A Monte Carlo study. Med Phys 2019; 46:3227-3234. [PMID: 31049969 DOI: 10.1002/mp.13561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 03/15/2019] [Accepted: 04/25/2019] [Indexed: 11/11/2022] Open
Abstract
PURPOSE The aim of this study is to propose a remote afterloading patient-specific brachytherapy technique for total scalp irradiation by utilizing liquid radioisotope as well as a three-dimensional (3D) printer and to find an optimal radioisotope for the suggested technique. METHODS We designed a brachytherapy device composed of liquid radioisotope tank, tube, patient-specific applicator, and a thin flexible pouch. The liquid radioisotope tank, tube, and the flexible pouch are interconnected one another to constitute a closed loop system. The pouch is located inside the solid patient-specific applicator; therefore, when the liquid radioisotope is injected into the pouch, the pouch is inflated and fills the space inside the applicator. The 3D-printed patient-specific applicator keeps the uniform thickness of the liquid radioisotope conforming patient's contour. To investigate an optimum condition for the suggested system, we performed Monte Carlo simulation with the GEANT4 simulation toolkit. To find the optimal radioisotope, percent depth doses (PDDs) of P-32, Sr-89, Y-90, and I-125 solutions were acquired in a rectangular parallelepiped phantom. For the selected radiation source, PDDs as well as dose rates in spherical phantoms with radii of 7.7 cm (infant head size) and 9.1 cm (adult head size) were acquired. RESULTS To deliver prescription doses at 4-mm depth regions (scalp region), 1-mm-thick Y-90 and 5-mm-thick I-125 in liquid form were found to be feasible for the suggested technique. For both spherical phantoms with radii of 7.7 and 9.1 cm, when delivering 2 Gy at the 4-mm depth region with the 1-mm-thick Y-90 and 5-mm-thick I-125 sources, 53.3 and 3.8 Gy were delivered at the surface regions, respectively (delivery time = 111.1 and 3.5 min with 1 GBq/ml solutions). The PDDs of Y-90 and I-125 became less than 1% at depths greater than 8 and 50 mm, respectively. CONCLUSIONS The remote afterloading patient-patient specific brachytherapy with I-125 or Y-90 in liquid form seems feasible for total scalp irradiation.
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Affiliation(s)
- Dongmin Ryu
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, 16229, Republic of Korea
| | - Jung-In Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 03080, Republic of Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - Sangmin Lee
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, 16229, Republic of Korea
| | - Sung-Joon Ye
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, 16229, Republic of Korea
| | - Jong Min Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 03080, Republic of Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Robotics Research Laboratory for Extreme Environments, Advanced Institutes of Convergence Technology, Suwon, 16229, Republic of Korea
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Zlateva Y, Muir BR, Seuntjens JP, El Naqa I. Cherenkov emission-based external radiotherapy dosimetry: II. Electron beam quality specification and uncertainties. Med Phys 2019; 46:2383-2393. [PMID: 30706493 DOI: 10.1002/mp.13413] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 01/06/2019] [Accepted: 01/15/2019] [Indexed: 11/05/2022] Open
Abstract
PURPOSE Cherenkov emission (CE) is ubiquitous in external radiotherapy. It is also unique in that it carries the promise of 3D, micrometer-resolution, perturbation-free, in-water dosimetry with a beam quality-independent detector response calibration. Our aim is to bring CE-based dosimetry into the clinic and we motivate this here with electron beams. We Monte Carlo (MC) calculate and characterize broad-beam CE-to-dose conversion factors in water for a clinically representative library of electron beam qualities, address beam quality specification and reference depth selection, and develop a preliminary uncertainty budget based on our MC results and relative experimental work of a companion study (Paper I). METHODS Broad electron beam CE-to-dose conversion factors k C θ ± δ θ include CE generated at polar angles θ ± δθ on beam axis in water. With modifications to the EGSnrc code SPRRZnrc, k C θ ± δ θ factors are calculated for a total of 20 electron beam qualities from four BEAMnrc models (Varian Clinac 2100C/D, Clinac 21EX, TrueBeam, and Elekta Precise). We examine beam quality, depth, and detection angle dependence for θ ± δ θ = 90 ∘ ± 90 ∘ (4π detection), 90 ∘ ± 5 ∘ , 45 ∘ ± 45 ∘ , and 90 ∘ ± 45 ∘ . As discussed in Paper I, 4π detection offers the strongest CE-dose correlation and θ = 90 ∘ with small δθ is most practical. The two additional configurations are considered as a compromise between these two extremes. We address beam quality specification and reference depth selection in terms of the electron beam quality specifier R 50 , obtained from the depth of 50% CE C 50 , and derive a best-case uncertainty budget for the CE-based dosimetry formalism proposed in Paper I at each detection configuration. RESULTS The k C θ ± δ θ factor was demonstrated to capture variations in the beam spectrum, angle, photon contamination, and electron fluence below the CE threshold (∼260 keV in the visible) in accordance with theory. The root-mean-square deviation and maximum deviation of a second-order polynomial fit of simulated R 50 values in terms of C 50 were 0.05 and 0.11 mm at 4π and 0.20 and 0.33 mm at 90 ∘ ± 5 ∘ detection, respectively. The fit performance on experimental data in Paper I was in agreement with these values within experimental uncertainties (±1.5 mm, 95% CI). A two-term power function fit of k C θ ± δ θ in terms of R 50 at a reference depth d ref = a R 50 + b resulted in total d ref -dependent dose uncertainty contribution estimate of 0.8% and 1.1% and preliminary best-case estimate of the combined standard dose uncertainty of 1.1% and 1.3% at 4π and 90 ∘ ± 5 ∘ detection, respectively. The results and corresponding uncertainties with the two intermediate apertures were generally of the same order as the 4π case. In addition, a theoretically consistent downstream shift of the percent-depth CE (PDC) by the difference between R 50 and C 50 improved the depth dependence of the 4π conversion by an order of magnitude (±2.8%). Therefore, a large aperture centered on a θ value between 45 ∘ and 90 ∘ combined with a downstream PDC shift may be recommended for beam-axis CE-based electron beam dosimetry in water. CONCLUSIONS By delivering R 50 -based CE-to-dose conversion data and demonstrating the potential for dosimetric uncertainty on the order of 1%, we bring CE-based electron beam dosimetry closer to clinical realization.
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Affiliation(s)
- Yana Zlateva
- Medical Physics Unit, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Bryan R Muir
- Metrology Research Centre, National Research Council Canada, Ottawa, ON, K1A 0R6, Canada
| | - Jan P Seuntjens
- Medical Physics Unit, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Issam El Naqa
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 48103-4943, USA
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Renaud M, Serban M, Seuntjens J. On mixed electron–photon radiation therapy optimization using the column generation approach. Med Phys 2017; 44:4287-4298. [DOI: 10.1002/mp.12338] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 05/01/2017] [Accepted: 05/03/2017] [Indexed: 01/02/2023] Open
Affiliation(s)
- Marc‐André Renaud
- Department of Physics & Medical Physics Unit McGill University Montreal Canada
| | - Monica Serban
- Medical Physics Unit McGill University Health Centre Montreal Canada
| | - Jan Seuntjens
- Medical Physics Unit McGill University and Research Institute of the McGill University Health Centre Montreal Canada
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Sung W, Park JI, Kim JI, Carlson J, Ye SJ, Park JM. Monte Carlo simulation for scanning technique with scattering foil free electron beam: A proof of concept study. PLoS One 2017; 12:e0177380. [PMID: 28493940 PMCID: PMC5426680 DOI: 10.1371/journal.pone.0177380] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/26/2017] [Indexed: 11/18/2022] Open
Abstract
This study investigated the potential of a newly proposed scattering foil free (SFF) electron beam scanning technique for the treatment of skin cancer on the irregular patient surfaces using Monte Carlo (MC) simulation. After benchmarking of the MC simulations, we removed the scattering foil to generate SFF electron beams. Cylindrical and spherical phantoms with 1 cm boluses were generated and the target volume was defined from the surface to 5 mm depth. The SFF scanning technique with 6 MeV electrons was simulated using those phantoms. For comparison, volumetric modulated arc therapy (VMAT) plans were also generated with two full arcs and 6 MV photon beams. When the scanning resolution resulted in a larger separation between beams than the field size, the plan qualities were worsened. In the cylindrical phantom with a radius of 10 cm, the conformity indices, homogeneity indices and body mean doses of the SFF plans (scanning resolution = 1°) vs. VMAT plans were 1.04 vs. 1.54, 1.10 vs. 1.12 and 5 Gy vs. 14 Gy, respectively. Those of the spherical phantom were 1.04 vs. 1.83, 1.08 vs. 1.09 and 7 Gy vs. 26 Gy, respectively. The proposed SFF plans showed superior dose distributions compared to the VMAT plans.
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Affiliation(s)
- Wonmo Sung
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Republic of Korea
| | - Jong In Park
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Republic of Korea
| | - Jung-in Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Joel Carlson
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Republic of Korea
| | - Sung-Joon Ye
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jong Min Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Institute for Smart System, Robotics Research Laboratory for Extreme Environments, Advanced Institutes of Convergence Technology, Suwon, Republic of Korea
- * E-mail:
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Maskani R, Tahmasebibirgani MJ, Hoseini-Ghahfarokhi M, Fatahiasl J. Determination of Initial Beam Parameters of Varian 2100 CD Linac for Various Therapeutic Electrons Using PRIMO. Asian Pac J Cancer Prev 2016; 16:7795-801. [PMID: 26625800 DOI: 10.7314/apjcp.2015.16.17.7795] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The aim of the present research was to establish primary characteristics of electron beams for a Varian 2100C/D linear accelerator with recently developed PRIMO Monte Carlo software and to verify relations between electron energy and dose distribution. To maintain conformity of simulated and measured dose curves within 1%/1mm, mean energy, Full Width at Half Maximum (FWHM) of energy and focal spot FWHM of initial beam were changed iteratively. Mean and most probable energies were extracted from validated phase spaces and compared with related empirical equation results. To explain the importance of correct estimation of primary energy on a clinical case, computed tomography images of a thorax phantom were imported in PRIMO. Dose distributions and dose volume histogram (DVH) curves were compared between validated and artificial cases with overestimated energy. Initial mean energies were obtained of 6.68, 9.73, 13.2 and 16.4 MeV for 6, 9, 12 and 15 nominal energies, respectively. Energy FWHM reduced with increase in energy. Three mm focal spot FWHM for 9 MeV and 4 mm for other energies made proper matches of simulated and measured profiles. In addition, the maximum difference of calculated mean electrons energy at the phantom surface with empirical equation was 2.2 percent. Finally, clear differences in DVH curves of validated and artificial energy were observed as heterogeneity indexes were 0.15 for 7.21 MeV and 0.25 for 6.68 MeV. The Monte Carlo model presented in PRIMO for Varian 2100 CD was precisely validated. IAEA polynomial equations estimated mean energy more accurately than a known linear one. Small displacement of R50 changed DVH curves and homogeneity indexes. PRIMO is a user-friendly software which has suitable capabilities to calculate dose distribution in water phantoms or computerized tomographic volumes accurately.
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Affiliation(s)
- Reza Maskani
- Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran E-mail :
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Park JI, Ha SW, Kim JI, Lee H, Lee J, Kim IH, Ye SJ. Design and evaluation of electron beam energy degraders for breast boost irradiation. Radiat Oncol 2016; 11:112. [PMID: 27580698 PMCID: PMC5007734 DOI: 10.1186/s13014-016-0686-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 08/19/2016] [Indexed: 11/25/2022] Open
Abstract
Background For breast cancer patients who require electron boost energies between 6 and 9 MeV, an energy degraders (ED) in the 9 MeV beamline was specially designed and manufactured to increase the skin dose of 6 MeV and to reduce the penetration depth of 9 MeV beams. Methods We used Monte Carlo (MC) techniques as a guide in the design of ED for use with linear accelerators. In order to satisfy percent depth dose (PDD) characteristics and dose profile uniformity in water, the shape and thickness of Lucite® ED in the 9 MeV beamline was iteratively optimized and then manufactured. The ED geometry consists of a truncated cone attached on top of a plane plate, with total central thickness of 1.0 cm. The ED was placed on the lower most scraper of the electron applicator. The PDDs, profiles, and output factors were measured in water to validate the MC-based design. Results Skin doses with the EDs increased by 8–9 %, compared to those of the 9 MeV beam. The outputs with the EDs were 0.882 and 0.972 for 10 × 10 and 15 × 15 cm2 cones, respectively, as compared to that of a conventional 9 MeV beam for a 10 × 10 cm2 cone. The X-ray contamination remained less than 1.5 %. In-vivo measurements were also performed for three breast boost patients and showed close agreement with expected values. Conclusions The optimally designed ED in the 9 MeV beamline provides breast conserving patients with a new energy option of 7 MeV for boost of the shallow tumor bed. It would be an alternative to bolus and thus eliminate inconvenience and concern about the daily variation of bolus setup.
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Affiliation(s)
- Jong In Park
- Department of Transdisciplinary Studies, Program in Biomedical Radiation Sciences, Seoul National University Graduate School of Convergence Science and Technology, Seoul, 151-742, Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.,Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea
| | - Sung Whan Ha
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.,Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea
| | - Jung-In Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.,Advanced Institutes of Convergence Technology, Seoul National University, Suwon, Korea
| | - Hyunseok Lee
- Department of Transdisciplinary Studies, Program in Biomedical Radiation Sciences, Seoul National University Graduate School of Convergence Science and Technology, Seoul, 151-742, Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea
| | - Jaegi Lee
- Department of Transdisciplinary Studies, Program in Biomedical Radiation Sciences, Seoul National University Graduate School of Convergence Science and Technology, Seoul, 151-742, Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea
| | - Il Han Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.,Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea
| | - Sung-Joon Ye
- Department of Transdisciplinary Studies, Program in Biomedical Radiation Sciences, Seoul National University Graduate School of Convergence Science and Technology, Seoul, 151-742, Korea. .,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea. .,Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea. .,Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea. .,Advanced Institutes of Convergence Technology, Seoul National University, Suwon, Korea.
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Rodrigues A, Sawkey D, Yin FF, Wu Q. A Monte Carlo simulation framework for electron beam dose calculations using Varian phase space files for TrueBeam Linacs. Med Phys 2015; 42:2389-403. [DOI: 10.1118/1.4916896] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Su S, Moran K, Robar JL. Design and production of 3D printed bolus for electron radiation therapy. J Appl Clin Med Phys 2014; 15:4831. [PMID: 25207410 PMCID: PMC5875499 DOI: 10.1120/jacmp.v15i4.4831] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 04/16/2014] [Accepted: 04/13/2014] [Indexed: 12/22/2022] Open
Abstract
This is a proof‐of‐concept study demonstrating the capacity for modulated electron radiation therapy (MERT) dose distributions using 3D printed bolus. Previous reports have involved bolus design using an electron pencil beam model and fabrication using a milling machine. In this study, an in‐house algorithm is presented that optimizes the dose distribution with regard to dose coverage, conformity, and homogeneity within the planning target volume (PTV). The algorithm takes advantage of a commercial electron Monte Carlo dose calculation and uses the calculated result as input. Distances along ray lines from the distal side of 90% isodose line to distal surface of the PTV are used to estimate the bolus thickness. Inhomogeneities within the calculation volume are accounted for using the coefficient of equivalent thickness method. Several regional modulation operators are applied to improve the dose coverage and uniformity. The process is iterated (usually twice) until an acceptable MERT plan is realized, and the final bolus is printed using solid polylactic acid. The method is evaluated with regular geometric phantoms, anthropomorphic phantoms, and a clinical rhabdomyosarcoma pediatric case. In all cases the dose conformity are improved compared to that with uniform bolus. For geometric phantoms with air or bone inhomogeneities, the dose homogeneity is markedly improved. The actual printed boluses conform well to the surface of complex anthropomorphic phantoms. The correspondence of the dose distribution between the calculated synthetic bolus and the actual manufactured bolus is shown. For the rhabdomyosarcoma patient, the MERT plan yields a reduction of mean dose by 38.2% in left kidney relative to uniform bolus. MERT using 3D printed bolus appears to be a practical, low‐cost approach to generating optimized bolus for electron therapy. The method is effective in improving conformity of the prescription isodose surface and in sparing immediately adjacent normal tissues. PACS number: 81.40.Wx
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Connell T, Alexander A, Papaconstadopoulos P, Serban M, Devic S, Seuntjens J. Delivery validation of an automated modulated electron radiotherapy plan. Med Phys 2014; 41:061715. [DOI: 10.1118/1.4876297] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Connell T, Seuntjens J. Design and validation of novel scattering foils for modulated electron radiation therapy. Phys Med Biol 2014; 59:2381-91. [DOI: 10.1088/0031-9155/59/10/2381] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Eldib A, Jin L, Li J, Charlie Ma CM. Investigation of the clinical potential of scattering foil free electron beams. Phys Med Biol 2014; 59:819-36. [DOI: 10.1088/0031-9155/59/4/819] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Jin L, Eldib A, Li J, Emam I, Fan J, Wang L, Ma CM. Measurement and Monte Carlo simulation for energy- and intensity-modulated electron radiotherapy delivered by a computer-controlled electron multileaf collimator. J Appl Clin Med Phys 2014; 15:4506. [PMID: 24423848 PMCID: PMC5711222 DOI: 10.1120/jacmp.v15i1.4506] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 09/25/2013] [Accepted: 09/15/2013] [Indexed: 11/23/2022] Open
Abstract
The dosimetric advantage of modulated electron radiotherapy (MERT) has been explored by many investigators and is considered to be an advanced radiation therapy technique in the utilization of electrons. A computer‐controlled electron multileaf collimator (MLC) prototype, newly designed to be added onto a Varian linac to deliver MERT, was investigated both experimentally and by Monte Carlo simulations. Four different electron energies, 6, 9, 12, and 15 MeV, were employed for this investigation. To ensure that this device was capable of delivering the electron beams properly, measurements were performed to examine the electron MLC (eMLC) leaf leakage and to determine the appropriate jaw positioning for an eMLC‐shaped field in order to eliminate a secondary radiation peak that could otherwise appear outside of an intended radiation field in the case of inappropriate jaw positioning due to insufficient radiation blockage from the jaws. Phase space data were obtained by Monte Carlo (MC) simulation and recorded at the plane just above the jaws for each of the energies (6, 9, 12, and 15 MeV). As an input source, phase space data were used in MC dose calculations for various sizes of the eMLC shaped field (10×10 cm2, 3.4×3.4 cm2, and 2×2 cm2) with respect to a water phantom at source‐to‐surface distance (SSD)=94cm, while the jaws, eMLC leaves, and some accessories associated with the eMLC assembly as well were modeled as modifiers in the calculations. The calculated results were then compared with measurements from a water scanning system. The results showed that jaw settings with 5 mm margins beyond the field shaped by the eMLC were appropriate to eliminate the secondary radiation peak while not widening the beam penumbra; the eMLC leaf leakage measurements ranged from 0.3% to 1.8% for different energies based on in‐phantom measurements, which should be quite acceptable for MERT. Comparisons between MC dose calculations and measurements showed agreement within 1%/1mm based on percentage depth doses (PDDs) and off‐axis dose profiles for a range of field sizes for each of the electron energies. Our current work has demonstrated that the eMLC and other relevant components in the linac were correctly modeled and simulated via our in‐house MC codes, and the eMLC is capable of accurately delivering electron beams for various eMLC‐shaped field sizes with appropriate jaw settings. In the next stage, patient‐specific verification with a full MERT plan should be performed. PACS number: 87.55.ne
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Papaconstadopoulos P, Seuntjens J. A source model for modulated electron radiation therapy using dynamic jaw movements. Med Phys 2013; 40:051707. [PMID: 23635255 DOI: 10.1118/1.4800492] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE The development of fast and accurate source models (SMs) might be of crucial importance for the future clinical implementation of modulated electron radiation therapy (MERT). In this study, a SM is presented for reconstructing phase-space information of modulated electron beams using a few-leaf electron collimator (FLEC) and the photon jaws. METHODS During a FLEC-based delivery, two collimation devices (jaws and FLEC) modulate the electron beam characteristics dynamically. The SM separates the beam into a primary and a scattered component. The primary component is derived by a fast Monte Carlo (MC) transport calculation in air using the EGSnrc/BEAMnrc code. The scattered beam is modeled analytically. The accelerator was decomposed into its individual leaf components and the scattered beam was characterized at various levels of the accelerator. Scattered particles are assigned an energy and position by sampling pre-calculated probability distributions. The direction is estimated by geometrical arguments. Particles were assumed to emerge from tunable virtual sources on the side of each collimator leaf. A leaf-hit algorithm was developed to dynamically reject particles that are incident on any collimating leaf. Electron transport in air between the two collimation levels was calculated based on a MC-modified version of the Fermi-Eyges scattering theory. Correlations between direction and position were observed and taken into account at the final collimation level. RESULTS To validate the model, reconstructed phase-space data were compared with the full accelerator MC phase-space data. The model accurately reproduced the beam characteristics and preserved important correlations. Depth and profile dose distributions in water were derived for square, rectangular, and off-axis field sizes and for a range of clinical energies. Discrepancies in the dose distributions and dose output were within 3% in all cases. CONCLUSIONS Fast and accurate SMs open the possibility for fast treatment planning in MERT, based on an inverse optimization MC treatment planning scheme.
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Affiliation(s)
- Pavlos Papaconstadopoulos
- Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Quebec H3G 1A4, Canada.
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Alexander A, Soisson E, Renaud MA, Seuntjens J. Direct aperture optimization for FLEC-based MERT and its application in mixed beam radiotherapy. Med Phys 2012; 39:4820-31. [DOI: 10.1118/1.4736423] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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