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Fisk M, Rowshanfarzad P, Pfefferlé D, Fernandez de Viana M, Cabrera J, Ebert MA. Development and optimisation of grid inserts for a preclinical radiotherapy system and corresponding Monte Carlo beam simulations. Phys Med Biol 2024; 69:055010. [PMID: 38262060 DOI: 10.1088/1361-6560/ad21a1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 01/23/2024] [Indexed: 01/25/2024]
Abstract
Objective. To develop a physical grid collimator compatible with the X-RAD preclinical radiotherapy system and create a corresponding Monte Carlo (MC) model.Approach. This work presents a methodology for the fabrication of a grid collimator designed for utilisation on the X-RAD preclinical radiotherapy system. Additionally, a MC simulation of the grid is developed, which is compatible with the X-RAD treatment planning system. The grid was manufactured by casting a low melting point alloy, cerrobend, into a silicone mould. The silicone was moulded around a 3D-printed replica of the grid, enabling the production of diverging holes with precise radii and spacing. A MC simulation was conducted on an equivalent 3D grid model and validated using 11 layers of GAFChromic EBT-3 film interspersed in a 3D-printed water-equivalent phantom. A 3D dose distribution was constructed from the film layers, enabling a direct comparison with the MC Simulation.Main results. The film and the MC dose distribution demonstrated a gamma passing rate of 99% for a 1%, 0.5 mm criteria with a 10% threshold applied. The peak-to-valley dose ratio and output factor at the surface were determined to be 20.4 and 0.79, respectively.Significance. The pairing of the grid collimator with a MC simulation can significantly enhance the practicality of grid therapy on the X-RAD. This combination enables further exploration of the biological implications of grid therapy, supported by a knowledge of the complex dose distributions. Moreover, this methodology can be adapted for use in other systems and scenarios.
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Affiliation(s)
- Marcus Fisk
- School of Physics, Mathematics, and Computing, University of Western Australia, Crawley WA, Australia
- Riverina Cancer Care Centre, Wagga Wagga NSW, Australia
| | - Pejman Rowshanfarzad
- School of Physics, Mathematics, and Computing, University of Western Australia, Crawley WA, Australia
- Centre for Advanced Technologies in Cancer Research (CATCR), Perth, Australia
| | - David Pfefferlé
- School of Physics, Mathematics, and Computing, University of Western Australia, Crawley WA, Australia
| | | | | | - Martin A Ebert
- School of Physics, Mathematics, and Computing, University of Western Australia, Crawley WA, Australia
- Centre for Advanced Technologies in Cancer Research (CATCR), Perth, Australia
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Hospital Ave, Nedlands WA, Australia
- 5D Clinics, Claremont, Western Australia, Australia
- School of Medicine and Public Health, University of Wisconsin, Madison WI, United States of America
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Breitkreutz DY, Skinner L, Lo S, Yu A. Nontoxic electron collimators. J Appl Clin Med Phys 2021; 22:73-81. [PMID: 34480841 PMCID: PMC8504586 DOI: 10.1002/acm2.13398] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/16/2021] [Accepted: 07/28/2021] [Indexed: 12/22/2022] Open
Abstract
Purpose The goal of this work was to develop and test nontoxic electron collimation technologies for clinical use. Methods Two novel technologies were investigated: tungsten‐silicone composite and 3D printed electron cutouts. Transmission, dose uniformity, and profiles were measured for the tungsten‐silicone. Surface dose, relative dose output, and field size were measured for the 3D printed cutouts and compared with the standard cerrobend cutouts in current clinical use. Quality assurance tests including mass measurements, Megavoltage (MV) imaging, and drop testing were developed for the 3D printed cutouts as a guide to safe clinical implementation. Results Dose profiles of the flexible tungsten‐silicone skin shields had an 80–20 penumbra values of 2–3 mm compared to 7–8 mm for cerrobend. In MV transmission image measurements of the tungsten‐silicone, 80% of the pixels had a transmission value within 2% of the mean. An ∼90% reduction in electron intensity was measured for 6 MeV and a 6.4 mm thickness of tungsten‐silicone and 12.7 mm thickness for 16 MeV. The maximum difference in 3D printed cutout versus cerrobend output, surface dose, and full width at half‐maximum (FWHM) was 1.7%, 1.2%, and 1.5%, respectively, for the 10 cm × 10 cm cutouts. Conclusions Both flexible tungsten‐silicone and 3D printed cutouts were found to be feasible for clinical use. The flexible tungsten‐silicone was of adequate density, flexibility, and uniformity to serve as skin shields for electron therapy. The 3D printed cutouts were dosimetrically equivalent to standard cerrobend cutouts and were robust enough for handling in the clinical environment.
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Affiliation(s)
| | - Lawrie Skinner
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Stephanie Lo
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Amy Yu
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
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Dosimetric evaluation of respiratory gated volumetric modulated arc therapy for lung stereotactic body radiation therapy using 3D printing technology. PLoS One 2018; 13:e0208685. [PMID: 30586367 PMCID: PMC6306268 DOI: 10.1371/journal.pone.0208685] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 11/22/2018] [Indexed: 02/07/2023] Open
Abstract
Purpose This study aimed to evaluate the dosimetric accuracy of respiratory gated volumetric modulated arc therapy (VMAT) for lung stereotactic body radiation therapy (SBRT) under simulation conditions similar to the actual clinical situation using patient-specific lung phantoms and realistic target movements. Methods Six heterogeneous lung phantoms were fabricated using a 3D-printer (3DISON, ROKIT, Seoul, Korea) to be dosimetrically equivalent to actual target regions of lung SBRT cases treated via gated VMAT. They were designed to move realistically via a motion device (QUASAR, Modus Medical Devices, Canada). Using the lung phantoms and a homogeneous phantom (model 500–3315, Modus Medical Devices), film dosimetry was performed with and without respiratory gating for VMAT delivery (TrueBeam STx; Varian Medical Systems, Palo Alto, CA, USA). The measured results were analyzed with the gamma passing rates (GPRs) of 2%/1 mm criteria, by comparing with the calculated dose via the AXB and AAA algorithms of the Eclipse Treatment Planning System (version 10.0.28; Varian Medical Systems). Results GPRs were greater than the acceptance criteria 80% for all film measurements with the stationary and homogeneous phantoms in conventional QAs. Regardless of the heterogeneity of phantoms, there were no significant differences (p > 0.05) in GPRs obtained with and without target motions; the statistical significance (p = 0.031) was presented between both algorithms under the utilization of heterogeneous phantoms. Conclusions Dosimetric verification with heterogeneous patient-specific lung phantoms could be successfully implemented as the evaluation method for gated VMAT delivery. In addition, it could be dosimetrically confirmed that the AXB algorithm improved the dose calculation accuracy under patient-specific simulations using 3D printed lung phantoms.
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Sharma A, Sasaki D, Rickey DW, Leylek A, Harris C, Johnson K, Alpuche Aviles JE, McCurdy B, Egtberts A, Koul R, Dubey A. Low-cost optical scanner and 3-dimensional printing technology to create lead shielding for radiation therapy of facial skin cancer: First clinical case series. Adv Radiat Oncol 2018; 3:288-296. [PMID: 30202798 PMCID: PMC6128099 DOI: 10.1016/j.adro.2018.02.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 01/04/2018] [Accepted: 02/07/2018] [Indexed: 11/19/2022] Open
Abstract
Purpose Three-dimensional printing has been implemented at our institution to create customized treatment accessories, including lead shields used during radiation therapy for facial skin cancer. To effectively use 3-dimensional printing, the topography of the patient must first be acquired. We evaluated a low-cost, structured-light, 3-dimensional, optical scanner to assess the clinical viability of this technology. Methods and materials For ease of use, the scanner was mounted to a simple gantry that guided its motion and maintained an optimum distance between the scanner and the object. To characterize the spatial accuracy of the scanner, we used a geometric phantom and an anthropomorphic head phantom. The geometric phantom was machined from plastic and included hemispherical and tetrahedral protrusions that were roughly the dimensions of an average forehead and nose, respectively. Polygon meshes acquired by the optical scanner were compared with meshes generated from high-resolution computed tomography images. Most optical scans contained minor artifacts. Using an algorithm that calculated the distances between the 2 meshes, we found that most of the optical scanner measurements agreed with those from the computed tomography scanner within approximately 1 mm for the geometric phantom and approximately 2 mm for the head phantom. We used this optical scanner along with 3-dimensional printer technology to create custom lead shields for 10 patients receiving orthovoltage treatments of nonmelanoma skin cancers of the face. Patient, tumor, and treatment data were documented. Results Lead shields created using this approach were accurate, fitting the contours of each patient's face. This process added to patient convenience and addressed potential claustrophobia and medical inability to lie supine. Conclusions The scanner was found to be clinically acceptable, and we suggest that the use of an optical scanner and 3-dimensional printer technology become the new standard of care to generate lead shielding for orthovoltage radiation therapy of nonmelanoma facial skin cancer.
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Affiliation(s)
- Ankur Sharma
- Department of Radiation Oncology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - David Sasaki
- Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Medical Physics, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Daniel W. Rickey
- Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Medical Physics, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Ahmet Leylek
- Department of Radiation Oncology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Chad Harris
- Department of Medical Physics, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Kate Johnson
- Department of Radiation Oncology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Jorge E. Alpuche Aviles
- Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Medical Physics, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Boyd McCurdy
- Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Medical Physics, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Andy Egtberts
- Department of Medical Physics, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Rashmi Koul
- Department of Radiation Oncology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Arbind Dubey
- Department of Radiation Oncology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
- Corresponding author. CancerCare Manitoba, ON 3258–675 McDermot Ave., Winnipeg, Manitoba R3E 0V9, Canada.
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Martínez-Rovira I, Puxeu-Vaqué J, Prezado Y. Dose evaluation of Grid Therapy using a 6 MV flattening filter-free (FFF) photon beam: A Monte Carlo study. Med Phys 2017; 44:5378-5383. [PMID: 28736809 DOI: 10.1002/mp.12485] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/11/2017] [Accepted: 07/15/2017] [Indexed: 12/27/2022] Open
Abstract
PURPOSE Spatially fractionated radiotherapy is a strategy to overcome the main limitation of radiotherapy, i.e., the restrained normal tissue tolerances. A well-known example is Grid Therapy, which is currently performed at some hospitals using megavoltage photon beams delivered by Linacs. Grid Therapy has been successfully used in the management of bulky abdominal tumors with low toxicity. The aim of this work was to evaluate whether an improvement in therapeutic index in Grid Therapy can be obtained by implementing it in a flattening filter-free (FFF) Linac. The rationale behind is that the removal of the flattening filter shifts the beam energy spectrum towards lower energies and increase the photon fluence. Lower energies result in a reduction of lateral scattering and thus, to higher peak-to-valley dose ratios (PVDR) in normal tissues. In addition, the gain in fluence might allow using smaller beams leading a more efficient exploitation of dose-volume effects, and consequently, a better normal tissue sparing. METHODS Monte Carlo simulations were used to evaluate realistic dose distributions considering a 6 MV FFF photon beam from a standard medical Linac and a cerrobend mechanical collimator in different configurations: grid sizes of 0.3 × 0.3 cm2 , 0.5 × 0.5 cm2 , and 1 × 1 cm2 and a corresponding center-to-center (ctc) distance of 0.6, 1, and 2 cm, respectively (total field size of 10 × 10 cm2 ). As figure of merit, peak doses in depth, PVDR, output factors (OF), and penumbra values were assessed. RESULTS Dose at the entrance is slightly higher than in conventional Grid Therapy. However, it is compensated by the large PVDR obtained at the entrance, reaching a maximum of 35 for a grid size of 1 × 1 cm2 . Indeed, this grid size leads to very high PVDR values at all depths (≥ 10), which are much higher than in standard Grid Therapy. This may be beneficial for normal tissues but detrimental for tumor control, where a lower PVDR might be requested. In that case, higher valley doses in the tumor could be achieved by using an interlaced approach and/or adapting the ctc distance. The smallest grid size (0.3 × 0.3 cm2 ) leads to low PVDR at all depths, comparable to standard Grid Therapy. However, the use of very thin beams might increase the normal tissue tolerances with respect to the grid size commonly used (1 × 1 cm2 ). The gain in fluence provided by FFF implies that the important OF reduction (0.6) will not increase treatment time. Finally, the intermediate configuration (0.5 × 0.5 cm2 ) provides high PVDR in the first 5 cm, and comparable PVDR to previous Grid Therapy works at depth. Therefore, this configuration might allow increasing the normal tissue tolerances with respect to Grid Therapy thanks to the higher PVDR and thinner beams, while a similar tumor control could be expected. CONCLUSIONS The implementation of Grid Therapy in an FFF photon beam from medical Linac might lead to an improvement of the therapeutic index. Among the cases evaluated, a grid size of 0.5 × 0.5 cm2 (1-cm-ctc) is the most advantageous configuration from the physics point of view. Radiobiological experiments are needed to fully explore this new avenue and to confirm our results.
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Affiliation(s)
- Immaculada Martínez-Rovira
- Department of Physics, Ionizing Radiation Research Group (GRRI), Universitat Autònoma de Barcelona, Campus UAB, Avinguda de l'Eix Central, Edicifi C, Cerdanyola del Vallès, 08193, Barcelona, Spain.,Laboratoire d'Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC), Centre National de la Recherche Scientifique (CNRS), Campus universitaire, Bât. 440, 1er étage - 15 rue Georges Clemenceau, 91406, Orsay cedex, France
| | - Josep Puxeu-Vaqué
- Servei de Protecció Radiològica i Física Mèdica, Hospital Universitari Sant Joan de Reus, Avinguda del Dr. Josep Laporte 2, 43204, Reus, Tarragona, Spain.,Servei de Física Mèdica i Protecció Radiològica, Institut Catalá d'Oncologia (ICO), Avinguda de la Granvia 199-203, Hospitalet de Llobregat, 08908, Barcelona, Spain
| | - Yolanda Prezado
- Laboratoire d'Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC), Centre National de la Recherche Scientifique (CNRS), Campus universitaire, Bât. 440, 1er étage - 15 rue Georges Clemenceau, 91406, Orsay cedex, France
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Gholami S, Nedaie HA, Longo F, Ay MR, Dini SA, Meigooni AS. Grid Block Design Based on Monte Carlo Simulated Dosimetry, the Linear Quadratic and Hug-Kellerer Radiobiological Models. J Med Phys 2017; 42:213-221. [PMID: 29296035 PMCID: PMC5744449 DOI: 10.4103/jmp.jmp_38_17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Purpose The clinical efficacy of Grid therapy has been examined by several investigators. In this project, the hole diameter and hole spacing in Grid blocks were examined to determine the optimum parameters that give a therapeutic advantage. Methods The evaluations were performed using Monte Carlo (MC) simulation and commonly used radiobiological models. The Geant4 MC code was used to simulate the dose distributions for 25 different Grid blocks with different hole diameters and center-to-center spacing. The therapeutic parameters of these blocks, namely, the therapeutic ratio (TR) and geometrical sparing factor (GSF) were calculated using two different radiobiological models, including the linear quadratic and Hug-Kellerer models. In addition, the ratio of the open to blocked area (ROTBA) is also used as a geometrical parameter for each block design. Comparisons of the TR, GSF, and ROTBA for all of the blocks were used to derive the parameters for an optimum Grid block with the maximum TR, minimum GSF, and optimal ROTBA. A sample of the optimum Grid block was fabricated at our institution. Dosimetric characteristics of this Grid block were measured using an ionization chamber in water phantom, Gafchromic film, and thermoluminescent dosimeters in Solid Water™ phantom materials. Results The results of these investigations indicated that Grid blocks with hole diameters between 1.00 and 1.25 cm and spacing of 1.7 or 1.8 cm have optimal therapeutic parameters (TR > 1.3 and GSF~0.90). The measured dosimetric characteristics of the optimum Grid blocks including dose profiles, percentage depth dose, dose output factor (cGy/MU), and valley-to-peak ratio were in good agreement (±5%) with the simulated data. Conclusion In summary, using MC-based dosimetry, two radiobiological models, and previously published clinical data, we have introduced a method to design a Grid block with optimum therapeutic response. The simulated data were reproduced by experimental data.
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Affiliation(s)
- Somayeh Gholami
- Department of Medical Physics and Biomedical Engineering, Radiotherapy Oncology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Hassan Ali Nedaie
- Department of Medical Physics and Biomedical Engineering, Radiotherapy Oncology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Francesco Longo
- Department of Physics, University of Trieste and INFN Trieste, Italy
| | - Mohammad Reza Ay
- Department of Medical Physics and Biomedical Engineering, Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Ali S Meigooni
- Comprehensive Cancer Centers of Nevada, Las Vegas, Nevada, USA
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