51
|
Darafsheh A, Hao Y, Zhao X, Zwart T, Wagner M, Evans T, Reynoso F, Zhao T. Spread-out Bragg peak proton FLASH irradiation using a clinical synchrocyclotron: Proof of concept and ion chamber characterization. Med Phys 2021; 48:4472-4484. [PMID: 34077590 DOI: 10.1002/mp.15021] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 11/08/2022] Open
Abstract
PURPOSE The purpose of this work is to (a) demonstrate the feasibility of delivering a spread-out Bragg peak (SOBP) proton beam in ultra-high dose rate (FLASH) using a proton therapy synchrocyclotron as a major step toward realizing an experimental platform for preclinical studies, and (b) evaluate the response of four models of ionization chambers in such a radiation field. METHODS A clinical Mevion HYPERSCAN® synchrocyclotron was adjusted for ultra-high dose rate proton delivery. Protons with nominal energy of 230 MeV were delivered in pulses with temporal width ranging from 12.5 μs to 24 μs spanning from conventional to FLASH dose rates. A boron carbide absorber and a range modulator block were placed in the beam path for range modulation and creating an SOBP dose profile. The radiation field was defined by a brass aperture with 11 mm diameter. Two Faraday cups were used to determine the number of protons per pulse at various dose rates. The dosimetric response of two cylindrical (IBA CC04 and CC13) and two plane-parallel (IBA PPC05 and PTW Advanced Markus® ) ionization chambers were evaluated. The dose rate was measured using the plane-parallel ionization chambers. The integral depth dose (IDD) was measured with a PTW Bragg Peak® ionization chamber. The lateral beam profile was measured with EBT-XD radiochromic film. Monte Carlo simulation was performed in TOPAS as the secondary check for the measurements and as a tool for further optimization of the range modulators' design. RESULTS Faraday cups measurement showed that the maximum protons per pulse is 39.9 pC at 24 μs pulse width. A good agreement between the measured and simulated IDD and lateral beam profiles was observed. The cylindrical ionization chambers showed very high ion recombination and deemed not suitable for absolute dosimetry at ultra-high dose rates. The average dose rate measured using the PPC05 ionization chamber was 163 Gy/s at the pristine Bragg peak and 126 Gy/s at 1 cm depth for the SOBP beam. The SOBP beam range and modulation were measured 24.4 mm and 19 mm, respectively. The pristine Bragg peak beam had 25.6 mm range. Simulation results showed that the IDD and profile flatness can be improved by the cavity diameter of the range modulator and the number of scanned spots, respectively. CONCLUSIONS Feasibility of delivering protons in an SOBP pattern with >100 Gy/s average dose rate using a clinical synchrocyclotron was demonstrated. The dose heterogeneity can be improved through optimization of the range modulator and number of delivered spots. Plane-parallel chambers with smaller gap between electrodes are more suitable for FLASH dosimetry compared to the other ion chambers used in this work.
Collapse
Affiliation(s)
- Arash Darafsheh
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Yao Hao
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Xiandong Zhao
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | | | | | | | - Francisco Reynoso
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Tianyu Zhao
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| |
Collapse
|
52
|
Boscolo D, Scifoni E, Durante M, Krämer M, Fuss MC. May oxygen depletion explain the FLASH effect? A chemical track structure analysis. Radiother Oncol 2021; 162:68-75. [PMID: 34214612 DOI: 10.1016/j.radonc.2021.06.031] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/14/2021] [Accepted: 06/23/2021] [Indexed: 12/16/2022]
Abstract
BACKGROUND AND PURPOSE Recent observations in animal models show that ultra-high dose rate ("FLASH") radiation treatment significantly reduces normal tissue toxicity maintaining an equivalent tumor control. The dependence of this "FLASH" effect on target oxygenation has led to the assumption that oxygen "depletion" could be its major driving force. MATERIALS AND METHODS In a bottom-up approach starting from the chemical track evolution of 1 MeV electrons in oxygenated water simulated with the TRAX-CHEM Monte Carlo code, we determine the oxygen consumption and radiolytic reactive oxygen species production following a short radiation pulse. Based on these values, the effective dose weighted by oxygen enhancement ratio (OER) or the in vitro cell survival under dynamic oxygen pressure is calculated and compared to that of conventional exposures, at constant OER. RESULTS We find an excellent agreement of our Monte Carlo predictions with the experimental value for radiolytic oxygen removal from oxygenated water. However, the application of the present model to published radiobiological experiment conditions shows that oxygen depletion can only have a negligible impact on radiosensitivity through oxygen enhancement, especially at typical experimental oxygenations where a FLASH effect has been observed. CONCLUSION We show that the magnitude and dependence of the "oxygen depletion" hypothesis are not consistent with the observed biological effects of FLASH irradiation. While oxygenation plays an undoubted role in mediating the FLASH effect, we conclude that state-of-the-art radiation chemistry models do not support oxygen depletion and radiation-induced transient hypoxia as the main mechanism.
Collapse
Affiliation(s)
- Daria Boscolo
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
| | - Emanuele Scifoni
- Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute for Nuclear Physics (INFN), Trento, Italy
| | - Marco Durante
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany; Institut für Physik Kondensierter Materie, Technische Universität Darmstadt, Germany.
| | - Michael Krämer
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
| | - Martina C Fuss
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.
| |
Collapse
|
53
|
Liew H, Mein S, Dokic I, Haberer T, Debus J, Abdollahi A, Mairani A. Deciphering Time-Dependent DNA Damage Complexity, Repair, and Oxygen Tension: A Mechanistic Model for FLASH-Dose-Rate Radiation Therapy. Int J Radiat Oncol Biol Phys 2021; 110:574-586. [DOI: 10.1016/j.ijrobp.2020.12.048] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 12/04/2020] [Accepted: 12/28/2020] [Indexed: 12/20/2022]
|
54
|
Jansen J, Knoll J, Beyreuther E, Pawelke J, Skuza R, Hanley R, Brons S, Pagliari F, Seco J. Does FLASH deplete oxygen? Experimental evaluation for photons, protons, and carbon ions. Med Phys 2021; 48:3982-3990. [PMID: 33948958 DOI: 10.1002/mp.14917] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 03/01/2021] [Accepted: 04/06/2021] [Indexed: 12/31/2022] Open
Abstract
PURPOSE To investigate experimentally, if FLASH irradiation depletes oxygen within water for different radiation types such as photons, protons, and carbon ions. METHODS This study presents measurements of the oxygen consumption in sealed, 3D-printed water phantoms during irradiation with x-rays, protons, and carbon ions at varying dose rates up to 340 Gy/s. The oxygen measurement was performed using an optical sensor allowing for noninvasive measurements. RESULTS Oxygen consumption in water only depends on dose, dose rate, and linear energy transfer (LET) of the irradiation. The total amount of oxygen depleted per 10 Gy was found to be 0.04% atm - 0.18% atm for 225 kV photons, 0.04% atm - 0.25% atm for 224 MeV protons, and 0.09% atm - 0.17% atm for carbon ions. Consumption depends on dose rate by an inverse power law and saturates for higher dose rates because of self-interactions of radicals. Higher dose rates yield lower oxygen consumption. No total depletion of oxygen was found for clinical doses. CONCLUSIONS FLASH irradiation does consume oxygen, but not enough to deplete all the oxygen present. For higher dose rates, less oxygen was consumed than at standard radiotherapy dose rates. No total depletion was found for any of the analyzed radiation types for 10 Gy dose delivery using FLASH.
Collapse
Affiliation(s)
- Jeannette Jansen
- Division of Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Faculty of Physics and Astronomy, Ruprecht-Karls-University, Heidelberg, Germany
| | - Jan Knoll
- Division of Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Faculty of Physics and Astronomy, Ruprecht-Karls-University, Heidelberg, Germany
| | - Elke Beyreuther
- OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.,Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
| | - Jörg Pawelke
- OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.,Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiooncology-OncoRay, Dresden, Germany
| | - Raphael Skuza
- Division of Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Faculty of Physics and Astronomy, Ruprecht-Karls-University, Heidelberg, Germany
| | - Rachel Hanley
- Division of Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Faculty of Physics and Astronomy, Ruprecht-Karls-University, Heidelberg, Germany
| | - Stephan Brons
- Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg, Germany
| | - Francesca Pagliari
- Division of Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Joao Seco
- Division of Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Faculty of Physics and Astronomy, Ruprecht-Karls-University, Heidelberg, Germany
| |
Collapse
|
55
|
Pawelke J, Brand M, Hans S, Hideghéty K, Karsch L, Lessmann E, Löck S, Schürer M, Szabó ER, Beyreuther E. Electron dose rate and oxygen depletion protect zebrafish embryos from radiation damage. Radiother Oncol 2021; 158:7-12. [DOI: 10.1016/j.radonc.2021.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 10/22/2022]
|
56
|
van Marlen P, Dahele M, Folkerts M, Abel E, Slotman BJ, Verbakel W. Ultra-High Dose Rate Transmission Beam Proton Therapy for Conventionally Fractionated Head and Neck Cancer: Treatment Planning and Dose Rate Distributions. Cancers (Basel) 2021; 13:cancers13081859. [PMID: 33924627 PMCID: PMC8070061 DOI: 10.3390/cancers13081859] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/02/2021] [Accepted: 04/11/2021] [Indexed: 12/02/2022] Open
Abstract
Simple Summary Standard intensity-modulated proton therapy (IMPT) places the Bragg-peak in the target. However, it is also possible to use high energy proton transmission beams (TBs), where the Bragg-peak is placed outside the patient, irradiating with the beam section proximal to the Bragg-peak. TBs use only one energy, increase robustness, are insensitive to density changes and have sharper penumbras. TBs can also be delivered at ultra-high dose-rates (UHDRs, e.g., ≥40 Gy/s), which is one of the requirements for the FLASH-effect. The aim of this work was twofold: (1) comparison of TB-plan quality to IMPT and photon volumetric-modulated arc therapy (VMAT) for conventionally fractionated head-and-neck cancer; (2) analysis of TB-plan UHDR-metrics. We showed that TB-plan quality was comparable to IMPT for contoured organs at risk and better than VMAT. Any potential FLASH-effect would only further improve plan quality. TB plans can also be delivered quickly, which might facilitate higher patient through-put and enhance patient comfort. Abstract Transmission beam (TB) proton therapy (PT) uses single, high energy beams with Bragg-peak behind the target, sharp penumbras and simplified planning/delivery. TB facilitates ultra-high dose-rates (UHDRs, e.g., ≥40 Gy/s), which is a requirement for the FLASH-effect. We investigated (1) plan quality for conventionally-fractionated head-and-neck cancer treatment using spot-scanning proton TBs, intensity-modulated PT (IMPT) and photon volumetric-modulated arc therapy (VMAT); (2) UHDR-metrics. VMAT, 3-field IMPT and 10-field TB-plans, delivering 70/54.25 Gy in 35 fractions to boost/elective volumes, were compared (n = 10 patients). To increase spot peak dose-rates (SPDRs), TB-plans were split into three subplans, with varying spot monitor units and different gantry currents. Average TB-plan organs-at-risk (OAR) sparing was comparable to IMPT: mean oral cavity/body dose were 4.1/2.5 Gy higher (9.3/2.0 Gy lower than VMAT); most other OAR mean doses differed by <2 Gy. Average percentage of dose delivered at UHDRs was 46%/12% for split/non-split TB-plans and mean dose-averaged dose-rate 46/21 Gy/s. Average total beam-on irradiation time was 1.9/3.8 s for split/non-split plans and overall time including scanning 8.9/7.6 s. Conventionally-fractionated proton TB-plans achieved comparable OAR-sparing to IMPT and better than VMAT, with total beam-on irradiation times <10s. If a FLASH-effect can be demonstrated at conventional dose/fraction, this would further improve plan quality and TB-protons would be a suitable delivery system.
Collapse
Affiliation(s)
- Patricia van Marlen
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands; (M.D.); (B.J.S.); (W.V.)
- Correspondence:
| | - Max Dahele
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands; (M.D.); (B.J.S.); (W.V.)
| | - Michael Folkerts
- Varian Medical Systems, 3120 Hansen Way, Palo Alto, CA 94304, USA; (M.F.); (E.A.)
| | - Eric Abel
- Varian Medical Systems, 3120 Hansen Way, Palo Alto, CA 94304, USA; (M.F.); (E.A.)
| | - Ben J. Slotman
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands; (M.D.); (B.J.S.); (W.V.)
| | - Wilko Verbakel
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands; (M.D.); (B.J.S.); (W.V.)
| |
Collapse
|
57
|
Soto LA, Casey KM, Wang J, Blaney A, Manjappa R, Breitkreutz D, Skinner L, Dutt S, Ko RB, Bush K, Yu AS, Melemenidis S, Strober S, Englemann E, Maxim PG, Graves EE, Loo BW. FLASH Irradiation Results in Reduced Severe Skin Toxicity Compared to Conventional-Dose-Rate Irradiation. Radiat Res 2021; 194:618-624. [PMID: 32853385 DOI: 10.1667/rade-20-00090] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/18/2020] [Indexed: 01/08/2023]
Abstract
Radiation therapy, along with surgery and chemotherapy, is one of the main treatments for cancer. While radiotherapy is highly effective in the treatment of localized tumors, its main limitation is its toxicity to normal tissue. Previous preclinical studies have reported that ultra-high dose-rate (FLASH) irradiation results in reduced toxicity to normal tissues while controlling tumor growth to a similar extent relative to conventional-dose-rate (CONV) irradiation. To our knowledge this is the first report of a dose-response study in mice comparing the effect of FLASH irradiation vs. CONV irradiation on skin toxicity. We found that FLASH irradiation results in both a lower incidence and lower severity of skin ulceration than CONV irradiation 8 weeks after single-fraction hemithoracic irradiation at high doses (30 and 40 Gy). Survival was also higher after FLASH hemithoracic irradiation (median survival >180 days at doses of 30 and 40 Gy) compared to CONV irradiation (median survival 100 and 52 days at 30 and 40 Gy, respectively). No ulceration was observed at doses 20 Gy or below in either FLASH or CONV. These results suggest a shifting of the dose-response curve for radiation-induced skin ulceration to the right for FLASH, compared to CONV irradiation, suggesting the potential for an enhanced therapeutic index for radiation therapy of cancer.
Collapse
Affiliation(s)
- Luis A Soto
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305.,Cancer Biology Program, Stanford University School of Medicine, Stanford, California 94305
| | - Kerriann M Casey
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford, California 94305
| | - Jinghui Wang
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305
| | - Alexandra Blaney
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford, California 94305
| | - Rakesh Manjappa
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305
| | - Dylan Breitkreutz
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305
| | - Lawrie Skinner
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305
| | - Suparna Dutt
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305.,Department of Medicine, Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, California 94305
| | - Ryan B Ko
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305
| | - Karl Bush
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305
| | - Amy S Yu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305
| | - Stavros Melemenidis
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305
| | - Samuel Strober
- Department of Medicine, Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, California 94305.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California 94305
| | - Edgar Englemann
- Department of Medicine, Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, California 94305.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California 94305.,Department of Pathology, Stanford University School of Medicine, Stanford, California 94305
| | - Peter G Maxim
- Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Edward E Graves
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California 94305.,Department of Pathology, Stanford University School of Medicine, Stanford, California 94305
| | - Billy W Loo
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California 94305.,Department of Pathology, Stanford University School of Medicine, Stanford, California 94305
| |
Collapse
|
58
|
Vozenin MC, Montay-Gruel P, Limoli C, Germond JF. All Irradiations that are Ultra-High Dose Rate may not be FLASH: The Critical Importance of Beam Parameter Characterization and In Vivo Validation of the FLASH Effect. Radiat Res 2021; 194:571-572. [PMID: 32853355 DOI: 10.1667/rade-20-00141.1] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 06/11/2020] [Indexed: 11/03/2022]
Affiliation(s)
- Marie-Catherine Vozenin
- Laboratory of Radiation Oncology, Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Pierre Montay-Gruel
- Laboratory of Radiation Oncology, Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.,Department of Radiation Oncology, University of California Irvine, Irvine, California
| | - Charles Limoli
- Department of Radiation Oncology, University of California Irvine, Irvine, California
| | - Jean-François Germond
- Institute of Radiation Physics/CHUV, Lausanne University Hospital, Lausanne, Switzerland
| |
Collapse
|
59
|
Chabi S, To THV, Leavitt R, Poglio S, Jorge PG, Jaccard M, Petersson K, Petit B, Roméo PH, Pflumio F, Vozenin MC, Uzan B. Ultra-high-dose-rate FLASH and Conventional-Dose-Rate Irradiation Differentially Affect Human Acute Lymphoblastic Leukemia and Normal Hematopoiesis. Int J Radiat Oncol Biol Phys 2021; 109:819-829. [PMID: 33075474 DOI: 10.1016/j.ijrobp.2020.10.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 09/30/2020] [Accepted: 10/09/2020] [Indexed: 02/08/2023]
Abstract
PURPOSE Ultra-high-dose-rate FLASH radiation therapy has been shown to minimize side effects of irradiation in various organs while keeping antitumor efficacy. This property, called the FLASH effect, has caused enthusiasm in the radiation oncology community because it opens opportunities for safe dose escalation and improved radiation therapy outcome. Here, we investigated the impact of ultra-high-dose-rate FLASH versus conventional-dose-rate (CONV) total body irradiation (TBI) on humanized models of T-cell acute lymphoblastic leukemia (T-ALL) and normal human hematopoiesis. METHODS AND MATERIALS We optimized the geometry of irradiation to ensure reproducible and homogeneous procedures using eRT6/Oriatron. Three T-ALL patient-derived xenografts and hematopoietic stem/progenitor cells (HSPCs) and CD34+ cells isolated from umbilical cord blood were transplanted into immunocompromised mice, together or separately. After reconstitution, mice received 4 Gy FLASH and CONV-TBI, and tumor growth and normal hematopoiesis were studied. A retrospective study of clinical and gene-profiling data previously obtained on the 3 T-ALL patient-derived xenografts was performed. RESULTS FLASH-TBI was more efficient than CONV-TBI in controlling the propagation of 2 cases of T-ALL, whereas the third case of T-ALL was more responsive to CONV-TBI. The 2 FLASH-sensitive cases of T-ALL had similar genetic abnormalities, and a putative susceptibility imprint to FLASH-RT was found. In addition, FLASH-TBI was able to preserve some HSPC/CD34+ cell potential. Interestingly, when HSPC and T-ALL were present in the same animals, FLASH-TBI could control tumor development in most (3 of 4) of the secondary grafted animals, whereas among the mice receiving CONV-TBI, treated cells died with high leukemia infiltration. CONCLUSIONS Compared with CONV-TBI, FLASH-TBI reduced functional damage to human blood stem cells and had a therapeutic effect on human T-ALL with a common genetic and genomic profile. The validity of the defined susceptibility imprint needs to be investigated further; however, to our knowledge, the present findings are the first to show benefits of FLASH-TBI on human hematopoiesis and leukemia treatment.
Collapse
Affiliation(s)
- Sara Chabi
- Team Niche and Cancer in Hematopoiesis, Fontenay-aux-Roses, France; Laboratoire des cellules Souches Hématopoïétiques et des Leucémies, Service Cellules Souches et Radiations, Fontenay-aux-Roses, France; UMRE008 Stabilité Génétique, Cellules Souches et Radiations, Université de Paris and Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Thi Hong Van To
- Laboratoire des cellules Souches Hématopoïétiques et des Leucémies, Service Cellules Souches et Radiations, Fontenay-aux-Roses, France; UMRE008 Stabilité Génétique, Cellules Souches et Radiations, Université de Paris and Université Paris-Saclay, Fontenay-aux-Roses, France; Laboratory of Radiation Oncology, Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, Switzerland
| | - Ron Leavitt
- Laboratory of Radiation Oncology, Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, Switzerland
| | - Sandrine Poglio
- Team Niche and Cancer in Hematopoiesis, Fontenay-aux-Roses, France; Laboratoire des cellules Souches Hématopoïétiques et des Leucémies, Service Cellules Souches et Radiations, Fontenay-aux-Roses, France; UMRE008 Stabilité Génétique, Cellules Souches et Radiations, Université de Paris and Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Patrik Gonçalves Jorge
- Laboratory of Radiation Oncology, Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, Switzerland; Institute of Radiation Physics/CHUV, Lausanne University Hospital, Switzerland
| | - Maud Jaccard
- Institute of Radiation Physics/CHUV, Lausanne University Hospital, Switzerland
| | - Kristoffer Petersson
- Laboratory of Radiation Oncology, Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, Switzerland; Institute of Radiation Physics/CHUV, Lausanne University Hospital, Switzerland
| | - Benoit Petit
- Laboratory of Radiation Oncology, Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, Switzerland
| | - Paul-Henri Roméo
- Team Niche and Cancer in Hematopoiesis, Fontenay-aux-Roses, France; UMRE008 Stabilité Génétique, Cellules Souches et Radiations, Université de Paris and Université Paris-Saclay, Fontenay-aux-Roses, France; Laboratoire de la Régulation de la Transcription dans les cellules Souches, Service Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Françoise Pflumio
- Team Niche and Cancer in Hematopoiesis, Fontenay-aux-Roses, France; Laboratoire des cellules Souches Hématopoïétiques et des Leucémies, Service Cellules Souches et Radiations, Fontenay-aux-Roses, France; UMRE008 Stabilité Génétique, Cellules Souches et Radiations, Université de Paris and Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Marie-Catherine Vozenin
- Laboratory of Radiation Oncology, Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, Switzerland.
| | - Benjamin Uzan
- Team Niche and Cancer in Hematopoiesis, Fontenay-aux-Roses, France; Laboratoire des cellules Souches Hématopoïétiques et des Leucémies, Service Cellules Souches et Radiations, Fontenay-aux-Roses, France; UMRE008 Stabilité Génétique, Cellules Souches et Radiations, Université de Paris and Université Paris-Saclay, Fontenay-aux-Roses, France
| |
Collapse
|
60
|
Marcu LG, Bezak E, Peukert DD, Wilson P. Translational Research in FLASH Radiotherapy-From Radiobiological Mechanisms to In Vivo Results. Biomedicines 2021; 9:181. [PMID: 33670409 PMCID: PMC7918545 DOI: 10.3390/biomedicines9020181] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 01/18/2023] Open
Abstract
FLASH radiotherapy, or the administration of ultra-high dose rate radiotherapy, is a new radiation delivery method that aims to widen the therapeutic window in radiotherapy. Thus far, most in vitro and in vivo results show a real potential of FLASH to offer superior normal tissue sparing compared to conventionally delivered radiation. While there are several postulations behind the differential behaviour among normal and cancer cells under FLASH, the full spectra of radiobiological mechanisms are yet to be clarified. Currently the number of devices delivering FLASH dose rate is few and is mainly limited to experimental and modified linear accelerators. Nevertheless, FLASH research is increasing with new developments in all the main areas: radiobiology, technology and clinical research. This paper presents the current status of FLASH radiotherapy with the aforementioned aspects in mind, but also to highlight the existing challenges and future prospects to overcome them.
Collapse
Affiliation(s)
- Loredana G Marcu
- Faculty of Informatics & Science, Department of Physics, University of Oradea, 410087 Oradea, Romania
- Cancer Research Institute and School of Health Sciences, University of South Australia, Adelaide, SA 5001, Australia
| | - Eva Bezak
- Cancer Research Institute and School of Health Sciences, University of South Australia, Adelaide, SA 5001, Australia
- School of Physical Sciences, Department of Physics, University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
| | - Dylan D Peukert
- School of Civil, Environmental & Mining Engineering, University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
- STEM, University of South Australia, Adelaide, SA 5001, Australia
| | - Puthenparampil Wilson
- STEM, University of South Australia, Adelaide, SA 5001, Australia
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, SA 5000, Australia
| |
Collapse
|
61
|
Khan S, Bassenne M, Wang J, Manjappa R, Melemenidis S, Breitkreutz DY, Maxim PG, Xing L, Loo BW, Pratx G. Multicellular Spheroids as In Vitro Models of Oxygen Depletion During FLASH Irradiation. Int J Radiat Oncol Biol Phys 2021; 110:833-844. [PMID: 33545301 DOI: 10.1016/j.ijrobp.2021.01.050] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 12/15/2020] [Accepted: 01/26/2021] [Indexed: 12/15/2022]
Abstract
PURPOSE The differential response of normal and tumor tissues to ultrahigh-dose-rate radiation (FLASH) has raised new hope for treating solid tumors but, to date, the mechanism remains elusive. One leading hypothesis is that FLASH radiochemically depletes oxygen from irradiated tissues faster than it is replenished through diffusion. The purpose of this study was to investigate these effects within hypoxic multicellular tumor spheroids through simulations and experiments. METHODS AND MATERIALS Physicobiological equations were derived to model (1) the diffusion and metabolism of oxygen within spheroids; (2) its depletion through reactions involving radiation-induced radicals; and (3) the increase in radioresistance of spheroids, modeled according to the classical oxygen enhancement ratio and linear-quadratic response. These predictions were then tested experimentally in A549 spheroids exposed to electron irradiation at conventional (0.075 Gy/s) or FLASH (90 Gy/s) dose rates. Clonogenic survival, cell viability, and spheroid growth were scored postradiation. Clonogenic survival of 2 other cell lines was also investigated. RESULTS The existence of a hypoxic core in unirradiated tumor spheroids is predicted by simulations and visualized by fluorescence microscopy. Upon FLASH irradiation, this hypoxic core transiently expands, engulfing a large number of well-oxygenated cells. In contrast, oxygen is steadily replenished during slower conventional irradiation. Experimentally, clonogenic survival was around 3-fold higher in FLASH-irradiated spheroids compared with conventional irradiation, but no significant difference was observed for well-oxygenated 2-dimensional cultured cells. This differential survival is consistent with the predictions of the computational model. FLASH irradiation of spheroids resulted in a dose-modifying factor of around 1.3 for doses above 10 Gy. CONCLUSIONS Tumor spheroids can be used as a model to study FLASH irradiation in vitro. The improved survival of tumor spheroids receiving FLASH radiation confirms that ultrafast radiochemical oxygen depletion and its slow replenishment are critical components of the FLASH effect.
Collapse
Affiliation(s)
- Syamantak Khan
- Department of Radiation Oncology, Stanford University, Stanford, California
| | - Maxime Bassenne
- Department of Radiation Oncology, Stanford University, Stanford, California
| | - Jinghui Wang
- Department of Radiation Oncology, Stanford University, Stanford, California
| | - Rakesh Manjappa
- Department of Radiation Oncology, Stanford University, Stanford, California
| | | | | | - Peter G Maxim
- Department of Radiation Oncology, Indiana University, Indianapolis, Indiana
| | - Lei Xing
- Department of Radiation Oncology, Stanford University, Stanford, California
| | - Billy W Loo
- Department of Radiation Oncology, Stanford University, Stanford, California
| | - Guillem Pratx
- Department of Radiation Oncology, Stanford University, Stanford, California.
| |
Collapse
|
62
|
Rothwell BC, Kirkby NF, Merchant MJ, Chadwick AL, Lowe M, Mackay RI, Hendry JH, Kirkby KJ. Determining the parameter space for effective oxygen depletion for FLASH radiation therapy. Phys Med Biol 2021; 66. [PMID: 33535191 PMCID: PMC8208623 DOI: 10.1088/1361-6560/abe2ea] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/03/2021] [Indexed: 01/20/2023]
Abstract
There has been a recent revival of interest in the FLASH effect, after experiments have shown normal tissue sparing capabilities of ultra-high-dose-rate radiation with no compromise on tumour growth restraint. A model has been developed to investigate the relative importance of a number of fundamental parameters considered to be involved in the oxygen depletion paradigm of induced radioresistance. An example eight-dimensional parameter space demonstrates the conditions under which radiation may induce sufficient depletion of oxygen for a diffusion-limited hypoxic cellular response. Initial results support experimental evidence that FLASH sparing is only achieved for dose rates on the order of tens of Gy/s or higher, for a sufficiently high dose, and only for tissue that is slightly hypoxic at the time of radiation. We show that the FLASH effect is the result of a number of biological, radiochemical and delivery parameters. Also, the threshold dose for a FLASH effect occurring would be more prominent when the parameterisation was optimised to produce the maximum effect. The model provides a framework for further FLASH-related investigation and experimental design. An understanding of the mechanistic interactions producing an optimised FLASH effect is essential for its translation into clinical practice.
Collapse
Affiliation(s)
- Bethany Cordelia Rothwell
- Division of Cancer Sciences, The University of Manchester Faculty of Biology Medicine and Health, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Norman F Kirkby
- Division of Cancer Sciences, The University of Manchester Faculty of Biology Medicine and Health, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Michael J Merchant
- Division of Cancer Sciences, The University of Manchester Faculty of Biology Medicine and Health, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Amy L Chadwick
- Division of Cancer Sciences, The University of Manchester Faculty of Biology Medicine and Health, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Matthew Lowe
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Ranald I Mackay
- Christie Medical Physics and Engineering , The Christie NHS Foundation Trust, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Jolyon H Hendry
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Karen J Kirkby
- Division of Cancer Sciences, The University of Manchester Faculty of Biology Medicine and Health, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| |
Collapse
|
63
|
Tumor Hypoxia as a Barrier in Cancer Therapy: Why Levels Matter. Cancers (Basel) 2021; 13:cancers13030499. [PMID: 33525508 PMCID: PMC7866096 DOI: 10.3390/cancers13030499] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/22/2021] [Accepted: 01/23/2021] [Indexed: 02/07/2023] Open
Abstract
Simple Summary Hypoxia is a common feature of solid tumors and associated with poor outcome in most cancer types and treatment modalities, including radiotherapy, chemotherapy, surgery and, most likely, immunotherapy. Emerging strategies, such as proton therapy and combination therapies with radiation and hypoxia targeted drugs, provide new opportunities to overcome the hypoxia barrier and improve therapeutic outcome. Hypoxia is heterogeneously distributed both between and within tumors and shows large variations across patients not only in prevalence, but importantly, also in level. To best exploit the emerging strategies, a better understanding of how individual hypoxia levels from mild to severe affect tumor biology is vital. Here, we discuss our current knowledge on this topic and how we should proceed to gain more insight into the field. Abstract Hypoxia arises in tumor regions with insufficient oxygen supply and is a major barrier in cancer treatment. The distribution of hypoxia levels is highly heterogeneous, ranging from mild, almost non-hypoxic, to severe and anoxic levels. The individual hypoxia levels induce a variety of biological responses that impair the treatment effect. A stronger focus on hypoxia levels rather than the absence or presence of hypoxia in our investigations will help development of improved strategies to treat patients with hypoxic tumors. Current knowledge on how hypoxia levels are sensed by cancer cells and mediate cellular responses that promote treatment resistance is comprehensive. Recently, it has become evident that hypoxia also has an important, more unexplored role in the interaction between cancer cells, stroma and immune cells, influencing the composition and structure of the tumor microenvironment. Establishment of how such processes depend on the hypoxia level requires more advanced tumor models and methodology. In this review, we describe promising model systems and tools for investigations of hypoxia levels in tumors. We further present current knowledge and emerging research on cellular responses to individual levels, and discuss their impact in novel therapeutic approaches to overcome the hypoxia barrier.
Collapse
|
64
|
Abdominal FLASH irradiation reduces radiation-induced gastrointestinal toxicity for the treatment of ovarian cancer in mice. Sci Rep 2020; 10:21600. [PMID: 33303827 PMCID: PMC7728763 DOI: 10.1038/s41598-020-78017-7] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 11/11/2020] [Indexed: 01/19/2023] Open
Abstract
Radiation therapy is the most effective cytotoxic therapy for localized tumors. However, normal tissue toxicity limits the radiation dose and the curative potential of radiation therapy when treating larger target volumes. In particular, the highly radiosensitive intestine limits the use of radiation for patients with intra-abdominal tumors. In metastatic ovarian cancer, total abdominal irradiation (TAI) was used as an effective postsurgical adjuvant therapy in the management of abdominal metastases. However, TAI fell out of favor due to high toxicity of the intestine. Here we utilized an innovative preclinical irradiation platform to compare the safety and efficacy of TAI ultra-high dose rate FLASH irradiation to conventional dose rate (CONV) irradiation in mice. We demonstrate that single high dose TAI-FLASH produced less mortality from gastrointestinal syndrome, spared gut function and epithelial integrity, and spared cell death in crypt base columnar cells compared to TAI-CONV irradiation. Importantly, TAI-FLASH and TAI-CONV irradiation had similar efficacy in reducing tumor burden while improving intestinal function in a preclinical model of ovarian cancer metastasis. These findings suggest that FLASH irradiation may be an effective strategy to enhance the therapeutic index of abdominal radiotherapy, with potential application to metastatic ovarian cancer.
Collapse
|
65
|
Folkerts MM, Abel E, Busold S, Perez JR, Krishnamurthi V, Ling CC. A framework for defining FLASH dose rate for pencil beam scanning. Med Phys 2020; 47:6396-6404. [PMID: 32910460 PMCID: PMC7894358 DOI: 10.1002/mp.14456] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 08/07/2020] [Accepted: 08/08/2020] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop a method of (a) calculating the dose rate of voxels within a proton field delivered using pencil beam scanning (PBS), and (b) reporting a representative dose rate for the PBS treatment field that enables correspondence between multiple treatment modalities. This method takes into account the unique spatiotemporal delivery patterns of PBS FLASH radiotherapy. METHODS The dose rate at each voxel of a PBS radiation field is approximately the quotient of the voxel's dose and "effective" irradiation time. Each voxel's "effective" irradiation time starts when the cumulative dose rises above a chosen threshold value, and stops when its cumulative dose reaches its total dose minus the same threshold value. The above calculation yields a distribution of dose rates for the voxels within a PBS treatment field. To report a representative dose rate for the PBS field, we propose a user-selectable parameter of pth percentile of the dose rate distribution, such that (100 - p) % of the field is above the corresponding dose rate. To demonstrate the method described above, we design FLASH transmission fields using 250 MeV protons and calculate the PBS dose rate distributions in both two-dimensional (2D) and three-dimensional (3D) models. To further evaluate the formalism, we provide an example of a clinical PBS treatment field. RESULTS With the 2D PBS transmission field, it is demonstrated that the time to accumulate the total dose at a voxel is limited to a fraction of the delivery time of the entire field. In addition, the spatial distributions of dose and dose rate are quite different within the field. For the 10 × 10 cm2 PBS field irradiating a 3D water phantom, the prescribed dose of 10 Gy at 10 cm depth is delivered in 1.0 s. The dose rate decreases in the irradiated volume with increasing depth (until the Bragg peak) due to increase of beam spot size by Coulomb scattering. For example, 95% of the irradiated volume between 0 and 10 cm depth receive >40 Gy/s, whereas between 0-20 cm and 0-30 cm depth, 95% of the irradiated volume received >36 Gy/s and >24 Gy/s, respectively. For the clinical PBS treatment field, the scanning pattern conforms to the PTV. PBS dose rate data are presented for the PTV and adjacent normal organs. CONCLUSION We have developed a method of calculating the dose rate distribution of a PBS proton field and have recommended nomenclature for reporting PBS treatment dose rate. We believe that standardizing the method for calculating and reporting PBS treatment dose rates, in a manner that corresponds with other treatment modalities, will advance the research and potential application of PBS FLASH radiotherapy.
Collapse
Affiliation(s)
| | - Eric Abel
- Varian Medical Systems, Inc, Palo Alto, CA, 94304, USA
| | - Simon Busold
- Varian Medical Systems Particle Therapy GmbH, Troisdorf, 53842, Germany
| | | | | | - C Clifton Ling
- Varian Medical Systems, Inc, Palo Alto, CA, 94304, USA.,Department of Radiation Oncology, Stanford University, Stanford, CA, 94305, USA.,Department of Radiation Oncology, Weill Cornell Medicine, New York, NY, 10003, USA
| |
Collapse
|
66
|
Zou W, Diffenderfer ES, Cengel KA, Kim MM, Avery S, Konzer J, Cai Y, Boisseu P, Ota K, Yin L, Wiersma R, Carlson DJ, Fan Y, Busch TM, Koumenis C, Lin A, Metz JM, Teo BK, Dong L. Current delivery limitations of proton PBS for FLASH. Radiother Oncol 2020; 155:212-218. [PMID: 33186682 DOI: 10.1016/j.radonc.2020.11.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 01/01/2023]
Abstract
PURPOSE Proton Pencil Beam Scanning (PBS) is an attractive solution to realize the advantageous normal tissue sparing elucidated from FLASH high dose rates. The mechanics of PBS spot delivery will impose limitations on the effective field dose rate for PBS. METHODS This study incorporates measurements from clinical and FLASH research beams on uniform single energy and the spread-out Bragg Peak PBS fields to extrapolate the PBS dose rate to high cyclotron beam currents 350, 500, and 800 nA. The impact of the effective field dose rate from cyclotron current, spot spacing, slew time and field size were studied. RESULTS When scanning magnet slew time and energy switching time are not considered, single energy effective field FLASH dose rate (≥40 Gy/s) can only be achieved with less than 4 × 4 cm2 fields when the cyclotron output current is above 500 nA. Slew time and energy switching time remain the limiting factors for achieving high effective dose rate of the field. The dose rate-time structures were obtained. The amount of the total dose delivered at the FLASH dose rate in single energy layer and volumetric field was also studied. CONCLUSION It is demonstrated that while it is difficult to achieve FLASH dose rate for a large field or in a volume, local FLASH delivery to certain percentage of the total dose is possible. With further understanding of the FLASH radiobiological mechanism, this study could provide guidance to adapt current clinical multi-field proton PBS delivery practice for FLASH proton radiotherapy.
Collapse
Affiliation(s)
- Wei Zou
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA.
| | - Eric S Diffenderfer
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Keith A Cengel
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Michele M Kim
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Steve Avery
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Joshua Konzer
- IBA PT-Inc., PT Engineer-Beam Physics, Louvain-La-Neuve, Belgium
| | - Yongliang Cai
- IBA PT-Inc., PT Engineer-Beam Physics, Louvain-La-Neuve, Belgium
| | - Paul Boisseu
- Pyramid Technical Consultants, Systems Engineering, Boston, USA
| | - Kan Ota
- Pyramid Technical Consultants, Systems Engineering, Boston, USA
| | - Lingshu Yin
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Rodney Wiersma
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - David J Carlson
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Yi Fan
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Theresa M Busch
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Costas Koumenis
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Alexander Lin
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - James M Metz
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - BoonKeng K Teo
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| | - Lei Dong
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA
| |
Collapse
|
67
|
Ramos-Méndez J, Domínguez-Kondo N, Schuemann J, McNamara A, Moreno-Barbosa E, Faddegon B. LET-Dependent Intertrack Yields in Proton Irradiation at Ultra-High Dose Rates Relevant for FLASH Therapy. Radiat Res 2020; 194:351-362. [PMID: 32857855 PMCID: PMC7644138 DOI: 10.1667/rade-20-00084.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 07/13/2020] [Indexed: 01/01/2023]
Abstract
FLASH radiotherapy delivers a high dose (≥10 Gy) at a high rate (≥40 Gy/s). In this way, particles are delivered in pulses as short as a few nanoseconds. At that rate, intertrack reactions between chemical species produced within the same pulse may affect the heterogeneous chemistry stage of water radiolysis. This stochastic process suits the capabilities of the Monte Carlo method, which can model intertrack effects to aid in radiobiology research, including the design and interpretation of experiments. In this work, the TOPAS-nBio Monte Carlo track-structure code was expanded to allow simulations of intertrack effects in the chemical stage of water radiolysis. Simulation of the behavior of radiolytic yields over a long period of time (up to 50 s) was verified by simulating radiolysis in a Fricke dosimeter irradiated by 60Co γ rays. In addition, LET-dependent G values of protons delivered in single squared pulses of widths, 1 ns, 1 µs and 10 µs, were obtained and compared to simulations using no intertrack considerations. The Fricke simulation for the calculated G value of Fe3+ ion at 50 s was within 0.4% of the accepted value from ICRU Report 34. For LET-dependent G values at the end of the chemical stage, intertrack effects were significant at LET values below 2 keV/µm. Above 2 keV/µm the reaction kinetics remained limited locally within each track and thus, effects of intertrack reactions remained low. Therefore, when track structure simulations are used to investigate the biological damage of FLASH irradiation, these intertrack reactions should be considered. The TOPAS-nBio framework with the expansion to intertrack chemistry simulation provides a useful tool to assist in this task.
Collapse
Affiliation(s)
- J. Ramos-Méndez
- Department of Radiation Oncology, University of California San Francisco, San Francisco, California
| | - N. Domínguez-Kondo
- Facultad de Ciencias Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - J. Schuemann
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - A. McNamara
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - E. Moreno-Barbosa
- Facultad de Ciencias Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Bruce Faddegon
- Department of Radiation Oncology, University of California San Francisco, San Francisco, California
| |
Collapse
|
68
|
FLASH Radiotherapy: Current Knowledge and Future Insights Using Proton-Beam Therapy. Int J Mol Sci 2020; 21:ijms21186492. [PMID: 32899466 PMCID: PMC7556020 DOI: 10.3390/ijms21186492] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/01/2020] [Accepted: 09/02/2020] [Indexed: 12/27/2022] Open
Abstract
FLASH radiotherapy is the delivery of ultra-high dose rate radiation several orders of magnitude higher than what is currently used in conventional clinical radiotherapy, and has the potential to revolutionize the future of cancer treatment. FLASH radiotherapy induces a phenomenon known as the FLASH effect, whereby the ultra-high dose rate radiation reduces the normal tissue toxicities commonly associated with conventional radiotherapy, while still maintaining local tumor control. The underlying mechanism(s) responsible for the FLASH effect are yet to be fully elucidated, but a prominent role for oxygen tension and reactive oxygen species production is the most current valid hypothesis. The FLASH effect has been confirmed in many studies in recent years, both in vitro and in vivo, with even the first patient with T-cell cutaneous lymphoma being treated using FLASH radiotherapy. However, most of the studies into FLASH radiotherapy have used electron beams that have low tissue penetration, which presents a limitation for translation into clinical practice. A promising alternate FLASH delivery method is via proton beam therapy, as the dose can be deposited deeper within the tissue. However, studies into FLASH protons are currently sparse. This review will summarize FLASH radiotherapy research conducted to date and the current theories explaining the FLASH effect, with an emphasis on the future potential for FLASH proton beam therapy.
Collapse
|
69
|
Griffin RJ, Prise KM, McMahon SJ, Zhang X, Penagaricano J, Butterworth KT. History and current perspectives on the biological effects of high-dose spatial fractionation and high dose-rate approaches: GRID, Microbeam & FLASH radiotherapy. Br J Radiol 2020; 93:20200217. [PMID: 32706989 DOI: 10.1259/bjr.20200217] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The effects of various forms of ionising radiation are known to be mediated by interactions with cellular and molecular targets in irradiated and in some cases non-targeted tissue volumes. Despite major advances in advanced conformal delivery techniques, the probability of normal tissue complication (NTCP) remains the major dose-limiting factor in escalating total dose delivered during treatment. Potential strategies that have shown promise as novel delivery methods in achieving effective tumour control whilst sparing organs at risk involve the modulation of critical dose delivery parameters. This has led to the development of techniques using high dose spatial fractionation (GRID) and ultra-high dose rate (FLASH) which have translated to the clinic. The current review discusses the historical development and biological basis of GRID, microbeam and FLASH radiotherapy as advanced delivery modalities that have major potential for widespread implementation in the clinic in future years.
Collapse
Affiliation(s)
- Robert J Griffin
- Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Kevin M Prise
- Patrick G Johnston Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Stephen J McMahon
- Patrick G Johnston Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Xin Zhang
- Department of Radiation Oncology, Boston University Medical Centre, Boston, MA, USA
| | - Jose Penagaricano
- Department of Radiation Oncology, Moffitt Cancer Centre, Tampa, FL, USA
| | - Karl T Butterworth
- Patrick G Johnston Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland, UK
| |
Collapse
|
70
|
Neuroprotection of Radiosensitive Juvenile Mice by Ultra-High Dose Rate FLASH Irradiation. Cancers (Basel) 2020; 12:cancers12061671. [PMID: 32599789 PMCID: PMC7352849 DOI: 10.3390/cancers12061671] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 06/02/2020] [Accepted: 06/18/2020] [Indexed: 02/07/2023] Open
Abstract
Major advances in high precision treatment delivery and imaging have greatly improved the tolerance of radiotherapy (RT); however, the selective sparing of normal tissue and the reduction of neurocognitive side effects from radiation-induced toxicities remain significant problems for pediatric patients with brain tumors. While the overall survival of pediatric patients afflicted with medulloblastoma (MB), the most common type primary brain cancer in children, remains high (≥80%), lifelong neurotoxic side-effects are commonplace and adversely impact patients’ quality of life. To circumvent these clinical complications, we have investigated the capability of ultra-high dose rate FLASH-radiotherapy (FLASH-RT) to protect the radiosensitive juvenile mouse brain from normal tissue toxicities. Compared to conventional dose rate (CONV) irradiation, FLASH-RT was found to ameliorate radiation-induced cognitive dysfunction in multiple independent behavioral paradigms, preserve developing and mature neurons, minimize microgliosis and limit the reduction of the plasmatic level of growth hormone. The protective “FLASH effect” was pronounced, especially since a similar whole brain dose of 8 Gy delivered with CONV-RT caused marked reductions in multiple indices of behavioral performance (objects in updated location, novel object recognition, fear extinction, light-dark box, social interaction), reductions in the number of immature (doublecortin+) and mature (NeuN+) neurons and increased neuroinflammation, adverse effects that were not found with FLASH-RT. Our data point to a potentially innovative treatment modality that is able to spare, if not prevent, many of the side effects associated with long-term treatment that disrupt the long-term cognitive and emotional well-being of medulloblastoma survivors.
Collapse
|
71
|
Jin JY, Gu A, Wang W, Oleinick NL, Machtay M, Spring Kong FM. Ultra-high dose rate effect on circulating immune cells: A potential mechanism for FLASH effect? Radiother Oncol 2020; 149:55-62. [PMID: 32387486 DOI: 10.1016/j.radonc.2020.04.054] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 12/28/2022]
Abstract
PURPOSE "FLASH" radiotherapy (RT) is a potential paradigm-changing RT technology with marked tumor killing and normal tissue sparing. However, the mechanism of the FLASH effect is not well understood. We hypothesize that the ultra-high dose rate FLASH-RT significantly reduces the killing of circulating immune cells which may partially contribute to the reported FLASH effect. METHODS This computation study directly models the effect of radiation dose rate on the killing of circulating immune cells. The model considers an irradiated volume that takes up A% of cardiac output and contains B% of total blood. The irradiated blood volume and dose were calculated for various A%, B%, blood circulation time, and irradiation time (which depends on the dose rate). The linear-quadratic model was used to calculate the extent of killing of circulating immune cells at ultra-high vs. conventional dose rates. RESULTS A strong sparing effect on circulating blood cells by FLASH-RT was noticed; i.e., killing of circulating immune cells reduced from 90% to 100% at conventional dose rates to 5-10% at ultra-high dose rates. The threshold FLASH dose rate was determined to be ~40 Gy/s for mice in an average situation (A% = 50%), consistent with the reported FLASH dose rate in animal studies, and it was approximately one order of magnitude lower for humans than for mice. The magnitude of this sparing effect increased with the dose/fraction, reached a plateau at 30-50 Gy/fraction, and almost completely vanished at 2 Gy/fraction. CONCLUSION We have calculated a strong sparing effect on circulating immune cells by FLASH-RT, which may contribute to the reported FLASH effects in animal studies.
Collapse
Affiliation(s)
- Jian-Yue Jin
- Department of Radiation Oncology, University Hospitals, Cleveland Medical Center, United States; Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, United States.
| | - Anxin Gu
- Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, United States; Department of Radiation Oncology, Harbin Medical University Cancer Hospital, China
| | - Weili Wang
- Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, United States
| | - Nancy L Oleinick
- Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, United States
| | - Mitchell Machtay
- Department of Radiation Oncology, University Hospitals, Cleveland Medical Center, United States; Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, United States
| | - Feng-Ming Spring Kong
- Department of Radiation Oncology, University Hospitals, Cleveland Medical Center, United States; Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, United States; Departments of Clinical Oncology, Hong Kong University Shenzhen Hospital, and Hong Kong University, Hong Kong, China
| |
Collapse
|