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Eling L, Kefs S, Keshmiri S, Balosso J, Calvet S, Chamel G, Drevon-Gaud R, Flandin I, Gaudin M, Giraud L, Laissue JA, Pellicioli P, Verry C, Adam JF, Serduc R. Neuro-Oncologic Veterinary Trial for the Clinical Transfer of Microbeam Radiation Therapy: Acute to Subacute Radiotolerance after Brain Tumor Irradiation in Pet Dogs. Cancers (Basel) 2024; 16:2701. [PMID: 39123429 PMCID: PMC11311398 DOI: 10.3390/cancers16152701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 07/08/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024] Open
Abstract
Synchrotron Microbeam Radiation Therapy (MRT) has repeatedly proven its superiority compared with conventional radiotherapy for glioma control in preclinical research. The clinical transfer phase of MRT has recently gained momentum; seven dogs with suspected glioma were treated under clinical conditions to determine the feasibility and safety of MRT. We administered a single fraction of 3D-conformal, image-guided MRT. Ultra-high-dose rate synchrotron X-ray microbeams (50 µm-wide, 400 µm-spaced) were delivered through five conformal irradiation ports. The PTV received ~25 Gy peak dose (within microbeams) per port, corresponding to a minimal cumulated valley dose (diffusing between microbeams) of 2.8 Gy. The dogs underwent clinical and MRI follow-up, and owner evaluations. One dog was lost to follow-up. Clinical exams of the remaining six dogs during the first 3 months did not indicate radiotoxicity induced by MRT. Quality of life improved from 7.3/10 [±0.7] to 8.9/10 [±0.3]. Tumor-induced seizure activity decreased significantly. A significant tumor volume reduction of 69% [±6%] was reached 3 months after MRT. Our study is the first neuro-oncologic veterinary trial of 3D-conformal Synchrotron MRT and reveals that MRT does not induce acute to subacute radiotoxicity in normal brain tissues. MRT improves quality of life and leads to remarkable tumor volume reduction despite low valley dose delivery. This trial is an essential step towards the forthcoming clinical application of MRT against deep-seated human brain tumors.
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Affiliation(s)
- Laura Eling
- Institut National de la Santé et de la Recherche Médicale UA7 Synchrotron Radiation for Biomedicine, Université Grenoble Alpes, 38400 Saint-Martin-d’Hères, France; (S.K.); (J.-F.A.); (R.S.)
- Centre Hospitalier Universitaire Grenoble Alpes, Maquis du Grésivaudan, 38700 La Tronche, France; (S.K.); (J.B.); (I.F.); (C.V.)
| | - Samy Kefs
- Centre Hospitalier Universitaire Grenoble Alpes, Maquis du Grésivaudan, 38700 La Tronche, France; (S.K.); (J.B.); (I.F.); (C.V.)
| | - Sarvenaz Keshmiri
- Institut National de la Santé et de la Recherche Médicale UA7 Synchrotron Radiation for Biomedicine, Université Grenoble Alpes, 38400 Saint-Martin-d’Hères, France; (S.K.); (J.-F.A.); (R.S.)
| | - Jacques Balosso
- Centre Hospitalier Universitaire Grenoble Alpes, Maquis du Grésivaudan, 38700 La Tronche, France; (S.K.); (J.B.); (I.F.); (C.V.)
| | - Susan Calvet
- Argos Clinique Vétérinaire Pierre du Terrail, 38530 Pontcharra, France;
| | - Gabriel Chamel
- Clinical Oncology Unit, Small Animal Internal Medicine Department, University of Lyon, VetAgro Sup Campus Vétérinaire, 69280 Marcy l’Etoile, France;
- Unité de Recherche Interaction Cellules Environnement, University of Lyon, VetAgro Sup Campus Vétérinaire, 69280 Marcy l’Etoile, France
| | | | - Isabelle Flandin
- Centre Hospitalier Universitaire Grenoble Alpes, Maquis du Grésivaudan, 38700 La Tronche, France; (S.K.); (J.B.); (I.F.); (C.V.)
| | - Maxime Gaudin
- OnlyVet, Centre Hospitalier Vétérinaire, 69800 Saint Priest, France; (M.G.); (L.G.)
| | - Lucile Giraud
- OnlyVet, Centre Hospitalier Vétérinaire, 69800 Saint Priest, France; (M.G.); (L.G.)
| | | | - Paolo Pellicioli
- European Synchrotron Radiation Facility, 38000 Grenoble, France;
| | - Camille Verry
- Centre Hospitalier Universitaire Grenoble Alpes, Maquis du Grésivaudan, 38700 La Tronche, France; (S.K.); (J.B.); (I.F.); (C.V.)
| | - Jean-François Adam
- Institut National de la Santé et de la Recherche Médicale UA7 Synchrotron Radiation for Biomedicine, Université Grenoble Alpes, 38400 Saint-Martin-d’Hères, France; (S.K.); (J.-F.A.); (R.S.)
- Centre Hospitalier Universitaire Grenoble Alpes, Maquis du Grésivaudan, 38700 La Tronche, France; (S.K.); (J.B.); (I.F.); (C.V.)
| | - Raphaël Serduc
- Institut National de la Santé et de la Recherche Médicale UA7 Synchrotron Radiation for Biomedicine, Université Grenoble Alpes, 38400 Saint-Martin-d’Hères, France; (S.K.); (J.-F.A.); (R.S.)
- Centre Hospitalier Universitaire Grenoble Alpes, Maquis du Grésivaudan, 38700 La Tronche, France; (S.K.); (J.B.); (I.F.); (C.V.)
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Gjaldbæk BW, Arendt ML, Konradsson E, Bastholm Jensen K, Bäck SÅ, Munck af Rosenschöld P, Ceberg C, Petersson K, Børresen B. Long-term toxicity and efficacy of FLASH radiotherapy in dogs with superficial malignant tumors. Front Oncol 2024; 14:1425240. [PMID: 39077466 PMCID: PMC11284943 DOI: 10.3389/fonc.2024.1425240] [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: 04/29/2024] [Accepted: 07/01/2024] [Indexed: 07/31/2024] Open
Abstract
Introduction FLASH radiotherapy (RT) has emerged as a promising modality, demonstrating both a normal tissue sparing effect and anticancer efficacy. We have previously reported on the safety and efficacy of single fraction FLASH RT in the treatment of oral tumors in canine cancer patients, showing tumor response but also a risk of radiation-induced severe late adverse effects (osteoradionecrosis) for doses ≥35 Gy. Accordingly, the objective in this study was to investigate if single fraction high dose FLASH RT is safe for treating non-oral tumors. Methods Privately-owned dogs with superficial tumors or microscopic residual disease were included. Treatment was generally delivered as a single fraction of 15-35 Gy 10 MeV electron FLASH RT, although two dogs were re-irradiated at a later timepoint. Follow-up visits were conducted up to 12 months post-treatment to evaluate treatment efficiency and adverse effects. Results Fourteen dogs with 16 tumors were included, of which nine tumors were treated for gross disease whilst seven tumors were treated post-surgery for microscopic residual disease. Four treatment sites treated with 35 Gy had ulceration post irradiation, which was graded as severe adverse effect. Only mild adverse effects were observed for the remaining treatment sites. None of the patients with microscopic disease experienced recurrence (0/7), and all patients with macroscopic disease showed either a complete (5/9) or a partial response (4/9). Five dogs were euthanized due to clinical disease progression. Discussion Our study demonstrates that single fraction high dose FLASH RT is generally safe, with few severe adverse effects, particularly in areas less susceptible to radiation-induced damage. In addition, our study indicates that FLASH has anti-tumor efficacy in a clinical setting. No osteoradionecrosis was observed in this study, although other types of high-grade adverse effects including ulcer-formations were observed for the highest delivered dose (35 Gy). Overall, we conclude that osteoradionecrosis following single fraction, high dose FLASH does not appear to be a general problem for non-oral tumor locations. Also, as has been shown previously for oral tumors, 30 Gy appeared to be the maximum safe dose to deliver with single fraction FLASH RT.
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Affiliation(s)
- Bolette W. Gjaldbæk
- Department of Veterinary Clinical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Maja L. Arendt
- Department of Veterinary Clinical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | | | - Sven Å. J. Bäck
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Per Munck af Rosenschöld
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Crister Ceberg
- Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Kristoffer Petersson
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
- Department of Oncology, Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Betina Børresen
- Department of Veterinary Clinical Sciences, University of Copenhagen, Frederiksberg, Denmark
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Kristensen L, Poulsen PR, Kanouta E, Rohrer S, Ankjærgaard C, Andersen CE, Johansen JG, Simeonov Y, Weber U, Grau C, Sørensen BS. Spread-out Bragg peak FLASH: quantifying normal tissue toxicity in a murine model. Front Oncol 2024; 14:1427667. [PMID: 39026976 PMCID: PMC11256197 DOI: 10.3389/fonc.2024.1427667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Accepted: 06/18/2024] [Indexed: 07/20/2024] Open
Abstract
Objective A favorable effect of ultra-high dose rate (FLASH) radiation on normal tissue-sparing has been indicated in several preclinical studies. In these studies, the adverse effects of radiation damage were reduced without compromising tumor control. Most studies of proton FLASH investigate these effects within the entrance of a proton beam. However, the real advantage of proton therapy lies in the Spread-out Bragg Peak (SOBP), which allows for giving a high dose to a target with a limited dose to healthy tissue at the entrance of the beam. Therefore, a clinically relevant investigation of the FLASH effect would be of healthy tissues within a SOBP. Our study quantified the tissue-sparing effect of FLASH radiation on acute and late toxicity within an SOBP in a murine model. Material/Methods Radiation-induced damage was assessed for acute and late toxicity in the same mice following irradiation with FLASH (Field dose rate of 60 Gy/s) or conventional (CONV, 0.34 Gy/s) dose rates. The right hindleg of unanesthetized female CDF1 mice was irradiated with single-fraction doses between 19.9-49.7 Gy for CONV and 30.4-65.9 Gy for FLASH with 5-8 mice per dose. The leg was placed in the middle of a 5 cm SOBP generated from a mono-energetic beam using a 2D range modulator. Acute skin toxicity quantified by hair loss, moist desquamation and toe separation was monitored daily within 29 days post-treatment. Late toxicity of fibrotic development measured by leg extendibility was monitored biweekly until 30 weeks post-treatment. Results Comparison of acute skin toxicity following radiation indicated a tissue-sparing effect of FLASH compared to conventional single-fraction radiation with a mean protection ratio of 1.40 (1.35-1.46). Fibrotic development similarly indicated normal tissue sparing with a 1.18 (1.17-1.18) protection ratio. The acute skin toxicity tissue sparing was similar to data from entrance-beam irradiations of Sørensen et al. (4). Conclusion Full dose-response curves for acute and late toxicity after CONV and FLASH radiation were obtained. Radiation within the SOBP retains the normal-tissue-sparing effect of FLASH with a dose-modifying factor of 40% for acute skin damage and 18% for fibrotic development.
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Affiliation(s)
- Line Kristensen
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
- Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Per Rugaard Poulsen
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Eleni Kanouta
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Sky Rohrer
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | | | | | - Jacob G. Johansen
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Yuri Simeonov
- Institut für Medizinische Physik und Strahlenschutz, Technische Hochschule Mittelhessen, Giessen, Germany
| | - Uli Weber
- Department for Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany
| | - Cai Grau
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Brita Singers Sørensen
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
- Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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Yan O, Wang S, Wang Q, Wang X. FLASH Radiotherapy: Mechanisms of Biological Effects and the Therapeutic Potential in Cancer. Biomolecules 2024; 14:754. [PMID: 39062469 PMCID: PMC11275005 DOI: 10.3390/biom14070754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 06/11/2024] [Accepted: 06/15/2024] [Indexed: 07/28/2024] Open
Abstract
Radiotherapy is an important treatment for many unresectable advanced malignant tumors, and radiotherapy-associated inflammatory reactions to radiation and other toxic side effects are significant reasons which reduce the quality of life and survival of patients. FLASH-radiotherapy (FLASH-RT), a prominent topic in recent radiation therapy research, is an ultra-high dose rate treatment known for significantly reducing therapy time while effectively targeting tumors. This approach minimizes radiation side effects on at-risk organs and maximally protects surrounding healthy tissues. Despite decades of preclinical exploration and some notable achievements, the mechanisms behind FLASH effects remain debated. Standardization is still required for the type of FLASH-RT rays and dose patterns. This review addresses the current state of FLASH-RT research, summarizing the biological mechanisms behind the FLASH effect. Additionally, it examines the impact of FLASH-RT on immune cells, cytokines, and the tumor immune microenvironment. Lastly, this review will discuss beam characteristics, potential clinical applications, and the relevance and applicability of FLASH-RT in treating advanced cancers.
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Affiliation(s)
| | | | | | - Xin Wang
- Division of Abdominal Tumor Multimodality Treatment, Department of Radiation Oncology, Cancer Center, West China Hospital of Sichuan University, Chengdu 610041, China; (O.Y.); (S.W.); (Q.W.)
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Giannini N, Gadducci G, Fuentes T, Gonnelli A, Di Martino F, Puccini P, Naso M, Pasqualetti F, Capaccioli S, Paiar F. Electron FLASH radiotherapy in vivo studies. A systematic review. Front Oncol 2024; 14:1373453. [PMID: 38655137 PMCID: PMC11035725 DOI: 10.3389/fonc.2024.1373453] [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: 01/20/2024] [Accepted: 03/15/2024] [Indexed: 04/26/2024] Open
Abstract
FLASH-radiotherapy delivers a radiation beam a thousand times faster compared to conventional radiotherapy, reducing radiation damage in healthy tissues with an equivalent tumor response. Although not completely understood, this radiobiological phenomenon has been proved in several animal models with a spectrum of all kinds of particles currently used in contemporary radiotherapy, especially electrons. However, all the research teams have performed FLASH preclinical studies using industrial linear accelerator or LINAC commonly employed in conventional radiotherapy and modified for the delivery of ultra-high-dose-rate (UHDRs). Unfortunately, the delivering and measuring of UHDR beams have been proved not to be completely reliable with such devices. Concerns arise regarding the accuracy of beam monitoring and dosimetry systems. Additionally, this LINAC totally lacks an integrated and dedicated Treatment Planning System (TPS) able to evaluate the internal dose distribution in the case of in vivo experiments. Finally, these devices cannot modify dose-time parameters of the beam relevant to the flash effect, such as average dose rate; dose per pulse; and instantaneous dose rate. This aspect also precludes the exploration of the quantitative relationship with biological phenomena. The dependence on these parameters need to be further investigated. A promising advancement is represented by a new generation of electron LINAC that has successfully overcome some of these technological challenges. In this review, we aim to provide a comprehensive summary of the existing literature on in vivo experiments using electron FLASH radiotherapy and explore the promising clinical perspectives associated with this technology.
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Affiliation(s)
- Noemi Giannini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Tuscany, Italy
- Centro Pisano Multidisciplinare Sulla Ricerca e Implementazione Clinica Della Flash Radiotherapy (CPFR), University of Pisa, Pisa, Italy
| | - Giovanni Gadducci
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Tuscany, Italy
- Centro Pisano Multidisciplinare Sulla Ricerca e Implementazione Clinica Della Flash Radiotherapy (CPFR), University of Pisa, Pisa, Italy
| | - Taiusha Fuentes
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Tuscany, Italy
- Centro Pisano Multidisciplinare Sulla Ricerca e Implementazione Clinica Della Flash Radiotherapy (CPFR), University of Pisa, Pisa, Italy
| | - Alessandra Gonnelli
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Tuscany, Italy
- Centro Pisano Multidisciplinare Sulla Ricerca e Implementazione Clinica Della Flash Radiotherapy (CPFR), University of Pisa, Pisa, Italy
| | - Fabio Di Martino
- Centro Pisano Multidisciplinare Sulla Ricerca e Implementazione Clinica Della Flash Radiotherapy (CPFR), University of Pisa, Pisa, Italy
- Unit of Medical Physics, Azienda Ospedaliero-Universitaria Pisana, Pisa, Tuscany, Italy
- National Institute of Nuclear Physics (INFN)-section of Pisa, Pisa, Tuscany, Italy
| | - Paola Puccini
- Department of Radiation Oncology, Azienda Ospedaliera Universitaria Pisana, University of Pisa, Pisa, Tuscany, Italy
| | - Monica Naso
- Department of Radiation Oncology, Azienda Ospedaliera Universitaria Pisana, University of Pisa, Pisa, Tuscany, Italy
| | - Francesco Pasqualetti
- Department of Radiation Oncology, Azienda Ospedaliera Universitaria Pisana, University of Pisa, Pisa, Tuscany, Italy
| | - Simone Capaccioli
- Centro Pisano Multidisciplinare Sulla Ricerca e Implementazione Clinica Della Flash Radiotherapy (CPFR), University of Pisa, Pisa, Italy
- Department of Physics, University of Pisa, Pisa, Tuscany, Italy
| | - Fabiola Paiar
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Tuscany, Italy
- Centro Pisano Multidisciplinare Sulla Ricerca e Implementazione Clinica Della Flash Radiotherapy (CPFR), University of Pisa, Pisa, Italy
- Department of Radiation Oncology, Azienda Ospedaliera Universitaria Pisana, University of Pisa, Pisa, Tuscany, Italy
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Cengel KA, Kim MM, Diffenderfer ES, Busch TM. FLASH Radiotherapy: What Can FLASH's Ultra High Dose Rate Offer to the Treatment of Patients With Sarcoma? Semin Radiat Oncol 2024; 34:218-228. [PMID: 38508786 DOI: 10.1016/j.semradonc.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
FLASH is an emerging treatment paradigm in radiotherapy (RT) that utilizes ultra-high dose rates (UHDR; >40 Gy)/s) of radiation delivery. Developing advances in technology support the delivery of UHDR using electron and proton systems, as well as some ion beam units (eg, carbon ions), while methods to achieve UHDR with photons are under investigation. The major advantage of FLASH RT is its ability to increase the therapeutic index for RT by shifting the dose response curve for normal tissue toxicity to higher doses. Numerous preclinical studies have been conducted to date on FLASH RT for murine sarcomas, alongside the investigation of its effects on relevant normal tissues of skin, muscle, and bone. The tumor control achieved by FLASH RT of sarcoma models is indistinguishable from that attained by treatment with standard RT to the same total dose. FLASH's high dose rates are able to mitigate the severity or incidence of RT side effects on normal tissues as evaluated by endpoints ranging from functional sparing to histological damage. Large animal studies and clinical trials of canine patients show evidence of skin sparing by FLASH vs. standard RT, but also caution against delivery of high single doses with FLASH that exceed those safely applied with standard RT. Also, a human clinical trial has shown that FLASH RT can be delivered safely to bone metastasis. Thus, data to date support continued investigations of clinical translation of FLASH RT for the treatment of patients with sarcoma. Toward this purpose, hypofractionated irradiation schemes are being investigated for FLASH effects on sarcoma and relevant normal tissues.
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Affiliation(s)
- Keith A Cengel
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania..
| | - Michele M Kim
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Eric S Diffenderfer
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Theresa M Busch
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Konradsson E, Ericsson Szecsenyi R, Wahlqvist P, Thoft A, Blad B, Bäck SÅ, Ceberg C, Petersson K. Reconfiguring a Plane-Parallel Transmission Ionization Chamber to Extend the Operating Range into the Ultra-High Dose-per-pulse Regime. Radiat Res 2024; 201:252-260. [PMID: 38308528 DOI: 10.1667/rade-23-00177.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 01/24/2024] [Indexed: 02/04/2024]
Abstract
This study aims to investigate the feasibility of enhancing the charge collection efficiency (CCE) of a transmission chamber by reconfiguring its design and operation. The goal was to extend the range of dose-per-pulse (DPP) values with no or minimal recombination effects up to the ultra-high dose rate (UHDR) regime. The response of two transmission chambers, with electrode distance of 1 mm and 0.6 mm, respectively, was investigated as a function of applied voltage. The chambers were mounted one-by-one in the electron applicator of a 10 MeV FLASH-modified clinical linear accelerator. The chamber signals were measured as a function of nominal DPP, which was determined at the depth of dose maximum using EBT-XD film in solid water and ranged from 0.6 mGy per pulse to 0.9 Gy per pulse, for both the standard voltage of 320 V and the highest possible safe voltage of 1,200 V. The CCE was calculated and fitted with an empirical logistic function that incorporated the electrode distance and the chamber voltage. The CCE decreased with increased DPP. The CCE at the highest achievable DPP was 24% (36%) at 320 V and 51% (82%) at 1,200 V, for chambers with 1 mm (0.6 mm) electrode distance. For the combination of 1,200 V- and 0.6-mm electrode distance, the CCE was ∼100% for average dose rate up to 70 Gy/s at the depth of dose maximum in the phantom at a source-to-surface distance of 100 cm. Our findings indicate that minor modifications to a plane-parallel transmission chamber can substantially enhance the CCE and extending the chamber's operating range to the UHDR regime. This supports the potential of using transmission chamber-based monitoring solutions for UHDR beams, which could facilitate the delivery of UHDR treatments using an approach similar to conventional clinical delivery.
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Affiliation(s)
- Elise Konradsson
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
| | | | - Pontus Wahlqvist
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Andreas Thoft
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Börje Blad
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Sven Åj Bäck
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Crister Ceberg
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Kristoffer Petersson
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
- Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom
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8
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Konradsson E, Wahlqvist P, Thoft A, Blad B, Bäck S, Ceberg C, Petersson K. Beam control system and output fine-tuning for safe and precise delivery of FLASH radiotherapy at a clinical linear accelerator. Front Oncol 2024; 14:1342488. [PMID: 38304871 PMCID: PMC10830783 DOI: 10.3389/fonc.2024.1342488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/03/2024] [Indexed: 02/03/2024] Open
Abstract
Introduction We have previously adapted a clinical linear accelerator (Elekta Precise, Elekta AB) for ultra-high dose rate (UHDR) electron delivery. To enhance reliability in future clinical FLASH radiotherapy trials, the aim of this study was to introduce and evaluate an upgraded beam control system and beam tuning process for safe and precise UHDR delivery. Materials and Methods The beam control system is designed to interrupt the beam based on 1) a preset number of monitor units (MUs) measured by a monitor detector, 2) a preset number of pulses measured by a pulse-counting diode, or 3) a preset delivery time. For UHDR delivery, an optocoupler facilitates external control of the accelerator's thyratron trigger pulses. A beam tuning process was established to maximize the output. We assessed the stability of the delivery, and the independent interruption capabilities of the three systems (monitor detector, pulse counter, and timer). Additionally, we explored a novel approach to enhance dosimetric precision in the delivery by synchronizing the trigger pulse with the charging cycle of the pulse forming network (PFN). Results Improved beam tuning of gun current and magnetron frequency resulted in average dose rates at the dose maximum at isocenter distance of >160 Gy/s or >200 Gy/s, with or without an external monitor chamber in the beam path, respectively. The delivery showed a good repeatability (standard deviation (SD) in total film dose of 2.2%) and reproducibility (SD in film dose of 2.6%). The estimated variation in DPP resulted in an SD of 1.7%. The output in the initial pulse depended on the PFN delay time. Over the course of 50 measurements employing PFN synchronization, the absolute percentage error between the delivered number of MUs calculated by the monitor detector and the preset MUs was 0.8 ± 0.6% (mean ± SD). Conclusion We present an upgraded beam control system and beam tuning process for safe and stable UHDR electron delivery of hundreds of Gy/s at isocenter distance at a clinical linac. The system can interrupt the beam based on monitor units and utilize PFN synchronization for improved dosimetric precision in the dose delivery, representing an important advancement toward reliable clinical FLASH trials.
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Affiliation(s)
- Elise Konradsson
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Pontus Wahlqvist
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Andreas Thoft
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Börje Blad
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Sven Bäck
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Crister Ceberg
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Kristoffer Petersson
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
- Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom
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Konradsson E, Szecsenyi RE, Adrian G, Coskun M, Børresen B, Arendt ML, Erhart K, Bäck SÅ, Petersson K, Ceberg C. Evaluation of intensity-modulated electron FLASH radiotherapy in a clinical setting using veterinary cases. Med Phys 2023; 50:6569-6579. [PMID: 37696040 DOI: 10.1002/mp.16737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 08/08/2023] [Accepted: 08/29/2023] [Indexed: 09/13/2023] Open
Abstract
PURPOSE The increased normal tissue tolerance for FLASH radiotherapy (FLASH-RT), as compared to conventional radiotherapy, was first observed in ultra-high dose rate electron beams. Initial clinical trials in companion animals have revealed a high risk of developing osteoradionecrosis following high-dose single-fraction electron FLASH-RT, which may be related to inhomogeneities in the dose distribution. In the current study, we aim to evaluate the possibilities of intensity-modulated electron FLASH-RT in a clinical setting to ensure a homogeneous dose distribution in future veterinary and human clinical trials. METHODS Our beam model in the treatment planning system electronRT (.decimal, LLC, Sanford, FL, USA) was based on a 10-MeV electron beam from a clinical linear accelerator used to treat veterinary patients with FLASH-RT in a clinical setting. In electronRT, the beam can be intensity-modulated using tungsten island blocks in the electron block cutout, and range-modulated using a customized bolus with variable thickness. Modulations were first validated in a heterogeneous phantom by comparing measured and calculated dose distributions. To evaluate the impact of intensity modulation in superficial single-fraction FLASH-RT, a treatment planning study was conducted, including eight canine cancer patient cases with simulated tumors in the head-and-neck region. For each case, treatment plans with and without intensity modulation were created for a uniform bolus and a range-modulating bolus. Treatment plans were evaluated using a target dose homogeneity index (HI), a conformity index (CI), the near-maximum dose outside the target (D 2 % , Body - PTV ${D_{2{\mathrm{\% }},{\mathrm{\ Body}} - {\mathrm{PTV}}}}$ ), and the near-minimum dose to the target (D 98 % ${D_{98\% }}$ ). RESULTS By adding intensity modulation to plans with a uniform bolus, the HI could be improved (p = 0.017). The combination of a range-modulating bolus and intensity modulation provided a further significant improvement of the HI as compared to using intensity modulation in combination with a uniform bolus (p = 0.036). The range-modulating bolus also improved the CI compared to using a uniform bolus, both with an open beam (p = 0.046) and with intensity modulation (p = 0.018), as well as increased theD 98 % ${D_{98\% }}$ (p = 0.036 with open beam and p = 0.05 with intensity modulation) and reduced the medianD 2 % , Body - PTV ${D_{2\% ,{\mathrm{\ Body}} - {\mathrm{PTV}}}}$ (not significant). CONCLUSIONS By using intensity-modulated electron FLASH-RT in combination with range-modulating bolus, the target dose homogeneity and conformity in canine patients with simulated tumors in complex areas in the head-and-neck region could be improved. By utilizing this technique, we hope to decrease the dose outside the target volume and avoid hot spots in future clinical electron FLASH-RT studies, thereby reducing the risk of radiation-induced toxicity.
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Affiliation(s)
- Elise Konradsson
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Rebecka Ericsson Szecsenyi
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Gabriel Adrian
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
- Division of Oncology and Pathology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Mizgin Coskun
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Betina Børresen
- Department of Veterinary Clinical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Maja Louise Arendt
- Department of Veterinary Clinical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | - Sven Åj Bäck
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Kristoffer Petersson
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
- Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Crister Ceberg
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
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