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Ashraf MR, Melemenidis S, Liu K, Grilj V, Jansen J, Velasquez B, Connell L, Schulz JB, Bailat C, Libed A, Manjappa R, Dutt S, Soto L, Lau B, Garza A, Larsen W, Skinner L, Yu AS, Surucu M, Graves EE, Maxim PG, Kry SF, Vozenin MC, Schüler E, Loo BW. Multi-Institutional Audit of FLASH and Conventional Dosimetry With a 3D Printed Anatomically Realistic Mouse Phantom. Int J Radiat Oncol Biol Phys 2024; 120:287-300. [PMID: 38493902 DOI: 10.1016/j.ijrobp.2024.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 03/03/2024] [Accepted: 03/10/2024] [Indexed: 03/19/2024]
Abstract
PURPOSE We conducted a multi-institutional dosimetric audit between FLASH and conventional dose rate (CONV) electron irradiations by using an anatomically realistic 3-dimensional (3D) printed mouse phantom. METHODS AND MATERIALS A computed tomography (CT) scan of a live mouse was used to create a 3D model of bony anatomy, lungs, and soft tissue. A dual-nozzle 3D printer was used to print the mouse phantom using acrylonitrile butadiene styrene (∼1.02 g/cm3) and polylactic acid (∼1.24 g/cm3) simultaneously to simulate soft tissue and bone densities, respectively. The lungs were printed separately using lightweight polylactic acid (∼0.64 g/cm3). Hounsfield units (HU), densities, and print-to-print stability of the phantoms were assessed. Three institutions were each provided a phantom and each institution performed 2 replicates of irradiations at selected anatomic regions. The average dose difference between FLASH and CONV dose distributions and deviation from the prescribed dose were measured with radiochromic film. RESULTS Compared with the reference CT scan, CT scans of the phantom demonstrated mass density differences of 0.10 g/cm3 for bone, 0.12 g/cm3 for lung, and 0.03 g/cm3 for soft tissue regions. Differences in HU between phantoms were <10 HU for soft tissue and bone, with lung showing the most variation (54 HU), but with minimal effect on dose distribution (<0.5%). Mean differences between FLASH and CONV decreased from the first to the second replicate (4.3%-1.2%), and differences from the prescribed dose decreased for both CONV (3.6%-2.5%) and FLASH (6.4%-2.7%). Total dose accuracy suggests consistent pulse dose and pulse number, although these were not specifically assessed. Positioning variability was observed, likely due to the absence of robust positioning aids or image guidance. CONCLUSIONS This study marks the first dosimetric audit for FLASH using a nonhomogeneous phantom, challenging conventional calibration practices reliant on homogeneous phantoms. The comparison protocol offers a framework for credentialing multi-institutional studies in FLASH preclinical research to enhance reproducibility of biologic findings.
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Affiliation(s)
- M Ramish Ashraf
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Stavros Melemenidis
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Kevin Liu
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Veljko Grilj
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Switzerland
| | - Jeannette Jansen
- Radiation Oncology Laboratory, Department of Radiation Oncology, Lausanne, University Hospital and University of Lausanne, Switzerland
| | - Brett Velasquez
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Luke Connell
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Joseph B Schulz
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Claude Bailat
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Switzerland
| | - Aaron Libed
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Rakesh Manjappa
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Suparna Dutt
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Luis Soto
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Brianna Lau
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Aaron Garza
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - William Larsen
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Lawrie Skinner
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Amy S Yu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Murat Surucu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Edward E Graves
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California
| | - Peter G Maxim
- Department of Radiation Oncology, University of California, Irvine, California
| | - Stephen F Kry
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas; Imaging and Radiation Oncology Core, MD Anderson Cancer Center, Houston, USA
| | - Marie-Catherine Vozenin
- Radiation Oncology Laboratory, Department of Radiation Oncology, Lausanne, University Hospital and University of Lausanne, Switzerland; Radiotherapy and Radiobiology Sector, Radiation Therapy Service, University Hospital of Geneva, Geneva, Switzerland.
| | - Emil Schüler
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
| | - Billy W Loo
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California.
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Bustillo JPO, Paino J, Barnes M, Cayley J, de Rover V, Cameron M, Engels EEM, Tehei M, Beirne S, Wallace GG, Rosenfeld AB, Lerch MLF. Design, construction, and dosimetry of 3D printed heterogeneous phantoms for synchrotron brain cancer radiation therapy quality assurance. Phys Med Biol 2024; 69:145003. [PMID: 38914107 DOI: 10.1088/1361-6560/ad5b48] [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: 03/29/2024] [Accepted: 06/24/2024] [Indexed: 06/26/2024]
Abstract
Objective.This study aims to design, manufacture, and test 3D printed quality assurance (QA) dosimetry phantoms for synchrotron brain cancer radiation therapy at the Australian synchrotron.Approach.Fabricated 3D printed phantoms from simple slab phantoms, a preclinical rat phantom, and an anthropomorphic head phantom were fabricated and characterized. Attenuation measurements of various polymers, ceramics and metals were acquired using synchrotron monochromatic micro-computed tomography (CT) imaging. Polylactic acid plus, VeroClear, Durable resin, and tricalcium phosphate were used in constructing the phantoms. Furthermore, 3D printed bone equivalent materials were compared relative to ICRU bone and hemihydrate plaster. Homogeneous and heterogeneous rat phantoms were designed and fabricated using tissue-equivalent materials. Geometric accuracy, CT imaging, and consistency were considered. Moreover, synchrotron broad-beam x-rays were delivered using a 3 Tesla superconducting multipole wiggler field for four sets of synchrotron radiation beam qualities. Dose measurements were acquired using a PinPoint ionization chamber and compared relative to a water phantom and a RMI457 Solid Water phantom. Experimental depth doses were compared relative to calculated doses using a Geant4 Monte Carlo simulation.Main results.Polylactic acid (PLA+) shows to have a good match with the attenuation coefficient of ICRU water, while both tricalcium phosphate and hydroxyapatite have good attenuation similarity with ICRU bone cortical. PLA+ material can be used as substitute to RMI457 slabs for reference dosimetry with a maximum difference of 1.84%. Percent depth dose measurement also shows that PLA+ has the best match with water and RMI457 within ±2.2% and ±1.6%, respectively. Overall, PLA+ phantoms match with RMI457 phantoms within ±3%.Significance and conclusion.The fabricated phantoms are excellent tissue equivalent equipment for synchrotron radiation dosimetry QA measurement. Both the rat and the anthropomorphic head phantoms are useful in synchrotron brain cancer radiotherapy dosimetry, experiments, and future clinical translation of synchrotron radiotherapy and imaging.
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Affiliation(s)
- John Paul O Bustillo
- Centre for Medical Radiation Physics, University of Wollongong Australia, Wollongong, NSW 2522, Australia
- Department of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Manila, Ermita, Manila City 1000 Metro Manila, The Philippines
| | - Jason Paino
- Centre for Medical Radiation Physics, University of Wollongong Australia, Wollongong, NSW 2522, Australia
| | - Micah Barnes
- Centre for Medical Radiation Physics, University of Wollongong Australia, Wollongong, NSW 2522, Australia
- Imaging and Medical Beamline, Australian Nuclear Science and Technology Organisation- Australian Synchrotron, Kulin Nation, Clayton, VIC 3168, Australia
| | - James Cayley
- Centre for Medical Radiation Physics, University of Wollongong Australia, Wollongong, NSW 2522, Australia
| | - Vincent de Rover
- Centre for Medical Radiation Physics, University of Wollongong Australia, Wollongong, NSW 2522, Australia
| | - Matthew Cameron
- Imaging and Medical Beamline, Australian Nuclear Science and Technology Organisation- Australian Synchrotron, Kulin Nation, Clayton, VIC 3168, Australia
| | - Elette E M Engels
- Centre for Medical Radiation Physics, University of Wollongong Australia, Wollongong, NSW 2522, Australia
- Imaging and Medical Beamline, Australian Nuclear Science and Technology Organisation- Australian Synchrotron, Kulin Nation, Clayton, VIC 3168, Australia
| | - Moeava Tehei
- Centre for Medical Radiation Physics, University of Wollongong Australia, Wollongong, NSW 2522, Australia
| | - Stephen Beirne
- Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, AIIM Facility, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Gordon G Wallace
- Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, AIIM Facility, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong Australia, Wollongong, NSW 2522, Australia
| | - Michael L F Lerch
- Centre for Medical Radiation Physics, University of Wollongong Australia, Wollongong, NSW 2522, Australia
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Polizzi M, Valerie K, Kim S. Commissioning and Assessment of Radiation Field and Dose Inhomogeneity for a Dual X-ray Tube Cabinet Irradiator: To Ensure Accurate Dosimetry in Radiation Biology Experiments. Adv Radiat Oncol 2024; 9:101486. [PMID: 38699670 PMCID: PMC11063221 DOI: 10.1016/j.adro.2024.101486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Accepted: 02/26/2024] [Indexed: 05/05/2024] Open
Abstract
Purpose Standardization of x-ray cabinet irradiator dose, geometry, and calibration reporting is an ongoing process. Multi-tube designs have been introduced into the preclinical market and give a theoretical benefit but have not been widely assessed for use in preclinical irradiation conditions. The aim of this study was to report our experience commissioning a dual x-ray source cabinet irradiator (CIXD, Xstrahl Limited, United Kingdom) and assess the dose distribution for various experimental conditions. Methods and Materials Half-value layer (HVL) measurement, profile measurements, and output calibration were performed using a calibrated ion chamber. Constancy measurements were performed twice daily over 2 weeks to assess output fluctuations. Film measurements were completed using solid water to assess percent depth dose and homogeneity within the field and within variable thicknesses of solid water and phosphate-buffered saline solution. Film measurements were repeated for various arrangements of petri dishes filled with phosphate-buffered saline or water and in a 3D-printed mouse phantom. Results The x-ray tubes had a measured in-air output of 1.27 Gy/min. The HVL was 1.7 mm Cu. The upper and lower tubes both exhibited the heel effect, but when operated simultaneously, the effect was reduced. Ion chamber measurements revealed a 15% dose inhomogeneity within the tray area (18 × 18 cm2). Film measurements in the petri dishes indicated minor nonuniformities in the arrangements of the experimental apparatus. Measurements from the mouse phantom with film agreed with ion chamber measurements for various phantom placements and orientations. Conclusions X-ray cell culture and animal irradiation with dual tube cabinet irradiation is efficient and robust when using established dosimetric tools to confirm output and homogeneity. The conditions assumed for calibrations are often not maintained during experiments. We have confirmed that inhomogeneities are present for single-tube use; however, they are reduced with simultaneous tube use. Additional dosimetric monitoring should be performed for each unique irradiation setup.
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Affiliation(s)
- Mitchell Polizzi
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia
| | - Kristoffer Valerie
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia
- Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia
| | - Siyong Kim
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia
- Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia
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Andrade EMR, Paixão L, Mendes BM, Fonseca TCF. RFPID: development and 3D-printing of a female physical phantom for whole-body counter. Biomed Phys Eng Express 2024; 10:045015. [PMID: 38697045 DOI: 10.1088/2057-1976/ad4650] [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: 11/17/2023] [Accepted: 05/02/2024] [Indexed: 05/04/2024]
Abstract
Whole-body counters (WBC) are used in internal dosimetry forin vivomonitoring in radiation protection. The calibration processes of a WBC set-up include the measurement of a physical phantom filled with a certificate radioactive source that usually is referred to a standard set of individuals determined by the International Commission on Radiological Protection (ICRP). The aim of this study was to develop an anthropomorphic and anthropometric female physical phantom for the calibration of the WBC systems. The reference female computational phantom of the ICRP, now called RFPID (Reference Female Phantom for Internal Dosimetry) was printed using PLA filament and with an empty interior. The goal is to use the RFPID to reduce the uncertainties associated within vivomonitoring system. The images which generated the phantom were manipulated using ImageJ®, Amide®, GIMP®and the 3D Slicer®software. RFPID was split into several parts and printed using a 3D printer in order to print the whole-body phantom. The newly printed physical phantom RFPID was successfully fabricated, and it is suitable to mimic human tissue, anatomically similar to a human body i.e., size, shape, material composition, and density.
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Affiliation(s)
- E M R Andrade
- Nuclear Engineering Department, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Nuclear Technology Development Center, Belo Horizonte, Minas Gerais, Brazil
| | - L Paixão
- Anatomy and Imaging Department, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - B M Mendes
- Nuclear Technology Development Center, Belo Horizonte, Minas Gerais, Brazil
| | - T C F Fonseca
- Nuclear Engineering Department, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Nuclear Technology Development Center, Belo Horizonte, Minas Gerais, Brazil
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5
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Antoniou A, Nikolaou A, Georgiou A, Evripidou N, Damianou C. Development of an US, MRI, and CT imaging compatible realistic mouse phantom for thermal ablation and focused ultrasound evaluation. ULTRASONICS 2023; 131:106955. [PMID: 36854247 DOI: 10.1016/j.ultras.2023.106955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/09/2022] [Accepted: 02/10/2023] [Indexed: 06/18/2023]
Abstract
Tissue mimicking phantoms (TMPs) play an essential role in modern biomedical research as cost-effective quality assurance and training tools, simultaneously contributing to the reduction of animal use. Herein, we present the development and evaluation of an anatomically accurate mouse phantom intended for image-guided thermal ablation and Focused Ultrasound (FUS) applications. The proposed mouse model consists of skeletal and soft tissue mimics, whose design was based on the Computed tomography (CT) scans data of a live mouse. Advantageously, it is compatible with US, CT, and Magnetic Resonance Imaging (MRI). The compatibility assessment was focused on the radiological behavior of the phantom due to the lack of relevant literature. The X-ray linear attenuation coefficient of candidate materials was estimated to assess the one that matches best the radiological behavior of living tissues. The bone part was manufactured by Fused Deposition Modeling (FDM) printing using Acrylonitrile styrene acrylate (ASA) material. For the soft-tissue mimic, a special mold was 3D printed having a cavity with the unique shape of the mouse body and filled with an agar-based silica-doped gel. The mouse phantom accurately matched the size and reproduced the body surface of the imaged mouse. Tissue-equivalency in terms of X-ray attenuation was demonstrated for the agar-based soft-tissue mimic. The phantom demonstrated excellent MRI visibility of the skeletal and soft-tissue mimics. Good radiological contrast between the skeletal and soft-tissue models was also observed in the CT scans. The model was also able to reproduce realistic behavior during trans-skull sonication as proved by thermocouple measurements. Overall, the proposed phantom is inexpensive, ergonomic, and realistic. It could constitute a powerful tool for image-guided thermal ablation and FUS studies in terms of testing and optimizing the performance of relevant equipment and protocols. It also possess great potential for use in transcranial FUS applications, including the emerging topic of FUS-mediated blood brain barrier (BBB) disruption.
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Affiliation(s)
- Anastasia Antoniou
- Department of Electrical Engineering, Computer Engineering, and Informatics, Cyprus University of Technology, Limassol, Cyprus.
| | - Anastasia Nikolaou
- Department of Electrical Engineering, Computer Engineering, and Informatics, Cyprus University of Technology, Limassol, Cyprus.
| | - Andreas Georgiou
- Department of Electrical Engineering, Computer Engineering, and Informatics, Cyprus University of Technology, Limassol, Cyprus.
| | - Nikolas Evripidou
- Department of Electrical Engineering, Computer Engineering, and Informatics, Cyprus University of Technology, Limassol, Cyprus.
| | - Christakis Damianou
- Department of Electrical Engineering, Computer Engineering, and Informatics, Cyprus University of Technology, Limassol, Cyprus.
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Biltekin F, Bäumer C, Esser J, Ghanem O, Ozyigit G, Timmermann B. Preclinical Dosimetry for Small Animal Radiation Research in Proton Therapy: A Feasibility Study. Int J Part Ther 2023; 10:13-22. [PMID: 37823014 PMCID: PMC10563666 DOI: 10.14338/ijpt-22-00035.1] [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: 10/04/2022] [Accepted: 02/10/2023] [Indexed: 10/13/2023] Open
Abstract
Purpose To evaluate the feasibility of the three-dimensional (3D) printed small animal phantoms in dosimetric verification of proton therapy for small animal radiation research. Materials and Methods Two different phantoms were modeled using the computed-tomography dataset of real rat and tumor-bearing mouse, retrospectively. Rat phantoms were designed to accommodate both EBT3 film and ionization chamber. A subcutaneous tumor-bearing mouse phantom was only modified to accommodate film dosimetry. All phantoms were printed using polylactic-acid (PLA) filament. Optimal printing parameters were set to create tissue-equivalent material. Then, proton therapy plans for different anatomical targets, including whole brain and total lung irradiation in the rat phantom and the subcutaneous tumor model in the mouse phantom, were created using the pencil-beam scanning technique. Point dose and film dosimetry measurements were performed using 3D-printed phantoms. In addition, all phantoms were analyzed in terms of printing accuracy and uniformity. Results Three-dimensionally printed phantoms had excellent uniformity over the external body, and printing accuracy was within 0.5 mm. According to our findings, two-dimensional dosimetry with EBT3 showed acceptable levels of γ passing rate for all measurements except for whole brain irradiation (γ passing rate, 89.8%). In terms of point dose analysis, a good agreement (<0.1%) was found between the measured and calculated point doses for all anatomical targets. Conclusion Three-dimensionally printed small animal phantoms show great potential for dosimetric verifications of clinical proton therapy for small animal radiation research.
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Affiliation(s)
- Fatih Biltekin
- Department of Radiation Oncology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
- West German Proton Therapy Centre Essen (WPE), Essen, Germany
| | - Christian Bäumer
- West German Proton Therapy Centre Essen (WPE), Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
- German Cancer Consortium (DKTK), Heidelberg, Germany
- TU Dortmund University, Department of Physics, Dortmund, Germany
| | - Johannes Esser
- West German Proton Therapy Centre Essen (WPE), Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
| | - Osamah Ghanem
- West German Proton Therapy Centre Essen (WPE), Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
| | - Gokhan Ozyigit
- Department of Radiation Oncology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Beate Timmermann
- West German Proton Therapy Centre Essen (WPE), Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
- German Cancer Consortium (DKTK), Heidelberg, Germany
- TU Dortmund University, Department of Physics, Dortmund, Germany
- Department of Particle Therapy, University Hospital Essen, Essen, Germany
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Entezam A, Fielding A, Bradley D, Fontanarosa D. Absorbed dose calculation for a realistic CT-derived mouse phantom irradiated with a standard Cs-137 cell irradiator using a Monte Carlo method. PLoS One 2023; 18:e0280765. [PMID: 36730280 PMCID: PMC9928120 DOI: 10.1371/journal.pone.0280765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 01/07/2023] [Indexed: 02/03/2023] Open
Abstract
Computed tomography (CT) derived Monte Carlo (MC) phantoms allow dose determination within small animal models that is not feasible with in-vivo dosimetry. The aim of this study was to develop a CT-derived MC phantom generated from a mouse with a xenograft tumour that could then be used to calculate both the dose heterogeneity in the tumour volume and out of field scattered dose for pre-clinical small animal irradiation experiments. A BEAMnrc Monte-Carlo model has been built of our irradiation system that comprises a lead collimator with a 1 cm diameter aperture fitted to a Cs-137 gamma irradiator. The MC model of the irradiation system was validated by comparing the calculated dose results with dosimetric film measurement in a polymethyl methacrylate (PMMA) phantom using a 1D gamma-index analysis. Dose distributions in the MC mouse phantom were calculated and visualized on the CT-image data. Dose volume histograms (DVHs) were generated for the tumour and organs at risk (OARs). The effect of the xenographic tumour volume on the scattered out of field dose was also investigated. The defined gamma index analysis criteria were met, indicating that our MC simulation is a valid model for MC mouse phantom dose calculations. MC dose calculations showed a maximum out of field dose to the mouse of 7% of Dmax. Absorbed dose to the tumour varies in the range 60%-100% of Dmax. DVH analysis demonstrated that tumour received an inhomogeneous dose of 12 Gy-20 Gy (for 20 Gy prescribed dose) while out of field doses to all OARs were minimized (1.29 Gy-1.38 Gy). Variation of the xenographic tumour volume exhibited no significant effect on the out of field scattered dose to OARs. The CT derived MC mouse model presented here is a useful tool for tumour dose verifications as well as investigating the doses to normal tissue (in out of field) for preclinical radiobiological research.
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Affiliation(s)
- Amir Entezam
- School of Clinical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
- Centre for Biomedical Technologies, Queensland University of Technology, Brisbane, QLD, Australia
- Translational Research Institute, The University of Queensland, Brisbane, QLD, Australia
- * E-mail:
| | - Andrew Fielding
- Centre for Biomedical Technologies, Queensland University of Technology, Brisbane, QLD, Australia
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, QLD, Australia
| | - David Bradley
- Centre for Applied Physics and Radiation Technologies, Sunway University, PJ, Malaysia
- Department of Physics, University of Surrey, Guildford, United Kingdom
| | - Davide Fontanarosa
- School of Clinical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
- Centre for Biomedical Technologies, Queensland University of Technology, Brisbane, QLD, Australia
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Esplen N, Egoriti L, Paley B, Planche T, Hoehr C, Gottberg A, Bazalova-Carter M. Design optimization of an electron-to-photon conversion target for ultra-high dose rate x-ray (FLASH) experiments at TRIUMF. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac5ed6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 03/17/2022] [Indexed: 12/29/2022]
Abstract
Abstract
Objective. To develop a bremsstrahlung target and megavoltage (MV) x-ray irradiation platform for ultrahigh dose-rate (UHDR) irradiation of small-animals on the Advanced Rare Isotope Laboratory (ARIEL) electron linac (e-linac) at TRIUMF. Approach. An electron-to-photon converter design for UHDR radiotherapy (RT) was centered around optimization of a tantalum–aluminum (Ta–Al) explosion-bonded target. Energy deposition within a homogeneous water-phantom and the target itself were evaluated using EGSnrc and FLUKA MC codes, respectively, for various target thicknesses (0.5–1.5 mm), beam energies (E
e− = 8, 10 MeV) and electron (Gaussian) beam sizes (
2
σ
= 2–10 mm). Depth dose-rates in a 3D-printed mouse phantom were also calculated to infer the compatibility of the 10 MV dose distributions for FLASH-RT in small-animal models. Coupled thermo-mechanical FEA simulations in ANSYS were subsequently used to inform the stress–strain conditions and fatigue life of the target assembly. Main results. Dose-rates of up to 128 Gy s−1 at the phantom surface, or 85 Gy s−1 at 1 cm depth, were obtained for a 1 × 1 cm2 field size, 1 mm thick Ta target and 7.5 cm source-to-surface distance using the FLASH-mode beam (E
e− = 10 MeV, 2
σ
= 5 mm, P = 1 kW); furthermore, removal of the collimation assembly and using a shorter (3.5 cm) SSD afforded dose-rates >600 Gy s−1, albeit at the expense of field conformality. Target temperatures were maintained below the tantalum, aluminum and cooling-water thresholds of 2000 °C, 300 °C and 100 °C, respectively, while the aluminum strain behavior remained everywhere elastic and helped ensure the converter survives its prescribed 5 yr operational lifetime. Significance. Effective design iteration, target cooling and failure mitigation have culminated in a robust target compatible with intensive transient (FLASH) and steady-state (diagnostic) applications. The ARIEL UHDR photon source will facilitate FLASH-RT experiments concerned with sub-second, pulsed or continuous beam irradiations at dose rates in excess of 40 Gy s−1.
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Price G, Biglin ER, Collins S, Aitkinhead A, Subiel A, Chadwick AL, Cullen DM, Kirkby KJ, Schettino G, Tipping J, Robinson A. An open source heterogeneous 3D printed mouse phantom utilising a novel bone representative thermoplastic. Phys Med Biol 2020; 65:10NT02. [PMID: 32182592 PMCID: PMC10606941 DOI: 10.1088/1361-6560/ab8078] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 03/17/2020] [Indexed: 11/12/2022]
Abstract
The lack of rigorous quality standards in pre-clinical radiation dosimetry has renewed interest in the development of anthropomorphic phantoms. Using 3D printing customisable phantoms can be created to assess all parts of pre-clinical radiation research: planning, image guidance and treatment delivery. We present the full methodology, including material development and printing designs, for the production of a high spatial resolution, anatomically realistic heterogeneous small animal phantom. A methodology for creating and validating tissue equivalent materials is presented. The technique is demonstrated through the development of a bone-equivalent material. This material is used together with a soft-tissue mimicking ABS plastic filament to reproduce the corresponding structure geometries captured from a CT scan of a nude mouse. Air gaps are used to represent the lungs. Phantom validation was performed through comparison of the geometry and x-ray attenuation of CT images of the phantom and animal images. A 6.6% difference in the attenuation of the bone-equivalent material compared to the reference standard in softer beams (0.5 mm Cu HVL) rapidly decreases as the beam is hardened. CT imaging shows accurate (sub-millimetre) reproduction of the skeleton (Distance-To-Agreement 0.5 mm ± 0.4 mm) and body surface (0.7 mm ± 0.5 mm). Histograms of the voxel intensity profile of the phantom demonstrate suitable similarity to those of both the original mouse image and that of a different animal. We present an approach for the efficient production of an anthropomorphic phantom suitable for the quality assurance of pre-clinical radiotherapy. Our design and full methodology are provided as open source to encourage the pre-clinical radiobiology community to adopt a common QA standard.
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Affiliation(s)
- Gareth Price
- University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, United Kingdom
- Authors contributed equally
- Author to whom any correspondence should be addressed
| | - Emma R Biglin
- University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, United Kingdom
- Authors contributed equally
| | - Sean Collins
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom
- Department of Physics, University of Surrey, Stag Hill, Guildford GU2 7XH, United Kingdom
| | - Adam Aitkinhead
- University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, United Kingdom
| | - Anna Subiel
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom
| | - Amy L Chadwick
- University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, United Kingdom
| | - David, M Cullen
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Karen J Kirkby
- University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, United Kingdom
| | - Giuseppe Schettino
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom
- Department of Physics, University of Surrey, Stag Hill, Guildford GU2 7XH, United Kingdom
| | - Jill Tipping
- Christie Medical Physics and Engineering (CMPE), The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, United Kingdom
| | - Andrew Robinson
- University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, United Kingdom
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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Esplen N, Therriault-Proulx F, Beaulieu L, Bazalova-Carter M. Preclinical dose verification using a 3D printed mouse phantom for radiobiology experiments. Med Phys 2019; 46:5294-5303. [PMID: 31461781 DOI: 10.1002/mp.13790] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 08/16/2019] [Accepted: 08/16/2019] [Indexed: 01/14/2023] Open
Abstract
PURPOSE Dose verification in preclinical radiotherapy is often challenged by a lack of standardization in the techniques and technologies commonly employed along with the inherent difficulty of dosimetry associated with small-field kilovoltage sources. As a consequence, the accuracy of dosimetry in radiobiological research has been called into question. Fortunately, the development and characterization of realistic small-animal phantoms has emerged as an effective and accessible means of improving dosimetric accuracy and precision in this context. The application of three-dimensional (3D) printing, in particular, has enabled substantial improvements in the conformity of representative phantoms with respect to the small animals they are modeled after. In this study, our goal was to evaluate a fully 3D printed mouse phantom for use in preclinical treatment verification of sophisticated therapies for various anatomical targets of therapeutic interest. METHODS An anatomically realistic mouse phantom was 3D printed based on segmented microCT data of a tumor-bearing mouse. The phantom was modified to accommodate both laser-cut EBT3 radiochromic film within the mouse thorax and a plastic scintillator dosimeter (PSD), which may be placed within the brain, abdomen, or 1-cm flank subcutaneous tumor. Various treatments were delivered on an image-guided small-animal irradiator in order to determine the doses to isocenter using a PSD and validate lateral- and depth-dose distributions using film dosimeters. On-board cone-beam CT imaging was used to localize isocenter to the film plane or PSD active element prior to irradiation. The PSD irradiations comprised a 3 × 3 mm2 brain arc, 5 × 5 mm2 parallel-opposed pair (POP), and 5-beam 10 × 10 mm2 abdominal coplanar arrangement while two-dimensional (2D) film dose distributions were acquired using a 3 × 3 mm2 arc and both 5 × 5 and 10 × 10 mm2 3-beam coplanar plans. A validated Monte Carlo (MC) model of the source was used as to verify the accuracy of the film and PSD dose measurements. computer-aided design (CAD) geometries for the mouse phantom and dosimeters were imported directly into the MC code to allow for highly accurate reproduction of the physical experiment conditions. Experimental and MC-derived film data were co-registered and film dose profiles were compared for points above 90% of the dose maximum. Point dose measurements obtained with the PSD were similarly compared for each of the candidate (brain, abdomen, and tumor) treatment sites. RESULTS For each treatment configuration and anatomical target, the MC-calculated and measured doses met the proposed 5% agreement goal for dose accuracy in radiobiology experiments. The 2D film and MC dose distributions were successfully registered and mean doses for lateral profiles were found to agree to within 2.3% in all cases. Isocentric point-dose measurements taken with the PSD were similarly consistent, with a maximum percentage deviation of 3.2%. CONCLUSIONS Our study confirms the utility of 3D printed phantom design in providing accurate dose estimates for a variety of preclinical treatment paradigms. As a tool for pretreatment dose verification, the phantom may be of particular interest to researchers for its ability to facilitate precise dosimetry while fostering a reduction in cost for radiobiology experiments.
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Affiliation(s)
- Nolan Esplen
- Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 5C2, Canada
| | - François Therriault-Proulx
- Departement de Radio-Oncologie and Centre de recherche du CHU de Quebec, CHU de Quebec, Quebec, QC, G1R 3S1, Canada
| | - Luc Beaulieu
- Departement de Radio-Oncologie and Centre de recherche du CHU de Quebec, CHU de Quebec, Quebec, QC, G1R 3S1, Canada.,Departement de physique and Centre de recherche sur le Cancer, Université Laval, Quebec, QC, G1V 0A6, Canada
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