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Scarmelotto A, Delprat V, Michiels C, Lucas S, Heuskin AC. The oxygen puzzle in FLASH radiotherapy: A comprehensive review and experimental outlook. Clin Transl Radiat Oncol 2024; 49:100860. [PMID: 39381632 PMCID: PMC11458961 DOI: 10.1016/j.ctro.2024.100860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 09/05/2024] [Accepted: 09/10/2024] [Indexed: 10/10/2024] Open
Abstract
FLASH radiotherapy is attracting increasing interest because it maintains tumor control while inflicting less damage to normal tissues compared to conventional radiotherapy. This sparing effect, the so-called FLASH effect, is achieved when radiation is delivered at ultra-high dose rates (≥40 Gy/s). Although the FLASH effect has already been demonstrated in several preclinical models, a complete mechanistic description explaining why tumors and normal tissues respond differently is still missing. None of the current hypotheses fully explains the experimental evidence. A common point between many of these is the role of oxygen, which is described as a major factor, either through transient hypoxia in the form of dissolved molecules, or reactive oxygen species (ROS). Therefore, this review focuses on both forms of this molecule, retracing old and more recent theories, while proposing new mechanisms that could provide a complete description of the FLASH effect based on preclinical and experimental evidence. In addition, this manuscript describes a set of experiments designed to provide the FLASH community with new tools for exploring the post-irradiation fate of ROS and their potential biological implications.
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Affiliation(s)
- Andrea Scarmelotto
- Laboratory for Analysis by Nuclear Reaction (LARN), Namur Research Institute for Life Sciences (NARILIS), University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
| | - Victor Delprat
- Laboratory for Analysis by Nuclear Reaction (LARN), Namur Research Institute for Life Sciences (NARILIS), University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
| | - Carine Michiels
- Unité de Recherche en Biologie Cellulaire (URBC), Namur Research Institute For Life Sciences (NARILIS), University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
| | - Stéphane Lucas
- Laboratory for Analysis by Nuclear Reaction (LARN), Namur Research Institute for Life Sciences (NARILIS), University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
- Ion Beam Application (IBA), Chemin du Cyclotron, 6, B-1348 Louvain-La-Neuve, Belgium
| | - Anne-Catherine Heuskin
- Laboratory for Analysis by Nuclear Reaction (LARN), Namur Research Institute for Life Sciences (NARILIS), University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
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Chaikh A, Édouard M, Huet C, Milliat F, Villagrasa C, Isambert A. Towards clinical application of ultra-high dose rate radiotherapy and the FLASH effect: Challenges and current status. Cancer Radiother 2024:S1278-3218(24)00122-7. [PMID: 39304401 DOI: 10.1016/j.canrad.2024.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 07/05/2024] [Accepted: 07/06/2024] [Indexed: 09/22/2024]
Abstract
Ultra-high dose rate external beam radiotherapy (UHDR-RT) uses dose rates of several tens to thousands of Gy/s, compared with the dose rate of the order of a few Gy/min for conventional radiotherapy techniques, currently used in clinical practice. The use of such dose rate is likely to improve the therapeutic index by obtaining a radiobiological effect, known as the "FLASH" effect. This would maintain tumor control while enhancing tissues protection. To date, this effect has been achieved using beams of electrons, photons, protons, and heavy ions. However, the conditions required to achieve this "FLASH" effect are not well defined, and raise several questions, particularly with regard to the definition of the prescription, including dose fractionation, irradiated volume and the temporal structure of the pulsed beam. In addition, the dose delivered over a very short period induces technical challenges, particularly in terms of detectors, which must be mastered to guarantee safe clinical implementation. IRSN has carried out an in-depth literature review of the UHDR-RT technique, covering various aspects relating to patient radiation protection: the radiobiological mechanisms associated with the FLASH effect, the used temporal structure of the UHDR beams, accelerators and dose control, the properties of detectors to be used with UHDR beams, planning, clinical implementation, and clinical studies already carried out or in progress.
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Affiliation(s)
| | | | | | - Fabien Milliat
- IRSN/PSE-SANTÉ-SERAMED/LRMed, Fontenay-aux-Roses, France
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Yamada R, Nishio T, Kinkawa D, Tanaka T, Omura M, Tabata Y, Yoshimura H, Kataoka J. Preliminary study of luminescence phenomena from various materials under ultra-high dose rate proton beam irradiation for dose management. Sci Rep 2024; 14:14504. [PMID: 38914610 PMCID: PMC11196681 DOI: 10.1038/s41598-024-65513-3] [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: 01/15/2024] [Accepted: 06/20/2024] [Indexed: 06/26/2024] Open
Abstract
This research aimed to identify materials capable of emitting visible light useful for dose management at ultra-high dose rate (uHDR). Various materials were irradiated with proton beams at a normal dose rate (NDR) and uHDR, and the resulting surface luminescence was captured using a high-sensitivity camera. The luminescence images were compared with the corresponding dose distributions. The luminescence of Tough Water Phantoms (Kyoto Kagaku Co. Ltd.) with various thicknesses was also observed to evaluate the depth distributions. Dose distributions were measured using two-dimensional ionization chamber detector arrays. The Tough Bone Phantom (Kyoto Kagaku Co. Ltd.) exhibited the strongest luminescence among the materials, followed by the Tough Water Phantom. The metals exhibited relatively weak luminescence. The luminescence profiles of the Tough Water Phantom, water, the Tough Lung Phantom (Kyoto Kagaku Co. Ltd.), and an acrylic were similar to the dose profiles. The luminescence distribution of the Tough Water Phantom in the depth direction was similar to that of the dose distributions. The luminescence at uHDR and NDR were approximately equivalent. The Tough Water Phantom was found to be a suitable material for dosimetry, even at uHDR. More detailed measurement data, such as wavelength data, must be collected to elucidate the luminescence mechanism.
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Affiliation(s)
- Ryosaku Yamada
- Medical Physics Laboratory, Division of Health Science, Graduate School of Medicine, Osaka University, Suita-shi, Osaka, Japan
- Department of Radiology, Kouseikai Takai Hospital, Tenri-shi, Nara, Japan
| | - Teiji Nishio
- Medical Physics Laboratory, Division of Health Science, Graduate School of Medicine, Osaka University, Suita-shi, Osaka, Japan.
| | - Daiki Kinkawa
- Medical Physics Laboratory, Division of Health Science, Graduate School of Medicine, Osaka University, Suita-shi, Osaka, Japan
| | - Taketo Tanaka
- Medical Physics Laboratory, Division of Health Science, Graduate School of Medicine, Osaka University, Suita-shi, Osaka, Japan
| | - Mizuki Omura
- Medical Physics Laboratory, Division of Health Science, Graduate School of Medicine, Osaka University, Suita-shi, Osaka, Japan
| | - Yoji Tabata
- Department of Radiology, Kouseikai Takai Hospital, Tenri-shi, Nara, Japan
| | - Hitoshi Yoshimura
- Department of Radiology, Kouseikai Takai Hospital, Tenri-shi, Nara, Japan
| | - Jun Kataoka
- Department of Pure and Applied Physics, Graduate School of Advanced Science and Engineering, Waseda University, Shinjyuku-ku, Tokyo, Japan
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4
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Taylor E, Létourneau D. How quickly does FLASH need to be delivered? A theoretical study of radiolytic oxygen depletion kinetics in tissues. Phys Med Biol 2024; 69:115008. [PMID: 38608644 DOI: 10.1088/1361-6560/ad3e5e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 04/12/2024] [Indexed: 04/14/2024]
Abstract
Purpose. Radiation delivered over ultra-short timescales ('FLASH' radiotherapy) leads to a reduction in normal tissue toxicities for a range of tissues in the preclinical setting. Experiments have shown this reduction occurs for total delivery times less than a 'critical' time that varies by two orders of magnitude between brain (∼0.3 s) and skin (⪆10 s), and three orders of magnitude across different bowel experiments, from ∼0.01 to ⪆(1-10) s. Understanding the factors responsible for this broad variation may be important for translation of FLASH into the clinic and understanding the mechanisms behind FLASH.Methods.Assuming radiolytic oxygen depletion (ROD) to be the primary driver of FLASH effects, oxygen diffusion, consumption, and ROD were evaluated numerically for simulated tissues with pseudorandom vasculatures for a range of radiation delivery times, capillary densities, and oxygen consumption rates (OCR's). The resulting time-dependent oxygen partial pressure distribution histograms were used to estimate cell survival in these tissues using the linear quadratic model, modified to incorporate oxygen-enhancement ratio effects.Results. Independent of the capillary density, there was a substantial increase in predicted cell survival when the total delivery time was less than the capillary oxygen tension (mmHg) divided by the OCR (expressed in units of mmHg/s), setting the critical delivery time for FLASH in simulated tissues. Using literature OCR values for different normal tissues, the predicted range of critical delivery times agreed well with experimental values for skin and brain and, modifying our model to allow for fluctuating perfusion, bowel.Conclusions. The broad three-orders-of-magnitude variation in critical irradiation delivery times observed inin vivopreclinical experiments can be accounted for by the ROD hypothesis and differences in the OCR amongst simulated normal tissues. Characterization of these may help guide future experiments and open the door to optimized tissue-specific clinical protocols.
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Affiliation(s)
- Edward Taylor
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Canada
- Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
| | - Daniel Létourneau
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Canada
- Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
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5
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McGarrigle JM, Long KR, Prezado Y. The FLASH effect-an evaluation of preclinical studies of ultra-high dose rate radiotherapy. Front Oncol 2024; 14:1340190. [PMID: 38711846 PMCID: PMC11071325 DOI: 10.3389/fonc.2024.1340190] [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: 11/17/2023] [Accepted: 03/20/2024] [Indexed: 05/08/2024] Open
Abstract
FLASH radiotherapy (FLASH-RT) is a novel radiotherapy approach based on the use of ultra-high dose radiation to treat malignant cells. Although tumours can be reduced or eradicated using radiotherapy, toxicities induced by radiation can compromise healthy tissues. The FLASH effect is the observation that treatment delivered at an ultra-high dose rate is able to reduce adverse toxicities present at conventional dose rates. While this novel technique may provide a turning point for clinical practice, the exact mechanisms underlying the causes or influences of the FLASH effect are not fully understood. The study presented here uses data collected from 41 experimental investigations (published before March 2024) of the FLASH effect. Searchable databases were constructed to contain the outcomes of the various experiments in addition to values of beam parameters that may have a bearing on the FLASH effect. An in-depth review of the impact of the key beam parameters on the results of the experiments was carried out. Correlations between parameter values and experimental outcomes were studied. Pulse Dose Rate had positive correlations with almost all end points, suggesting viability of FLASH-RT as a new modality of radiotherapy. The collective results of this systematic review study suggest that beam parameter qualities from both FLASH and conventional radiotherapy can be valuable for tissue sparing and effective tumour treatment.
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Affiliation(s)
| | - Kenneth Richard Long
- Department of Physics, Imperial College London, London, United Kingdom
- Science and Technology Facilities Council (STFC), Rutherford Appleton Laboratory, Oxford, United Kingdom
| | - Yolanda Prezado
- Institut Curie, Universite Paris-Saclay, Centre national de la recherche scientifique (CNRS) UMR3347, Inserm U1021, Signalisation radiobiologie et cancer, Orsay, France
- Universite Paris-Saclay, Centre national de la recherche scientifique (CNRS) UMR3347, Inserm U1021, Signalisation radiobiologie et cancer, Orsay, France
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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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Cetnar AJ, Jain S, Gupta N, Chakravarti A. Technical note: Commissioning of a linear accelerator producing ultra-high dose rate electrons. Med Phys 2024; 51:1415-1420. [PMID: 38159300 DOI: 10.1002/mp.16925] [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: 06/21/2023] [Revised: 12/12/2023] [Accepted: 12/18/2023] [Indexed: 01/03/2024] Open
Abstract
BACKGROUND Ultra-high dose rate radiation (UHDR) is being explored by researchers in promise of advancing radiation therapy treatments. PURPOSE This work presents the commissioning of Varian's Flash Extension for research (FLEX) conversion of a Clinac to deliver UHDR electrons. METHODS A Varian Clinac iX with the FLEX conversion was commissioned for non-clinical research use with 16 MeV UHDR (16H) energy. This involved addition of new hardware, optimizing the electron gun voltages, radiofrequency (RF) power, and steering coils in order to maximize the accelerated electron beam current, sending the beam through custom scattering foils to produce the UHDR with 16H beam. Profiles and percent depth dose (PDD) measurements for 16H were obtained using radiochromic film in a custom vertical film holder and were compared to 16 MeV conventional electrons (16C). Dose rate and dose per pulse (DPP) were calculated from measured dose in film. Linearity and stability were assessed using an Advanced Markus ionization chamber. RESULTS Energies for 16H and 16C had similar beam quality based on PDD measurements. Measurements at the head of the machine (61.3 cm SSD) with jaws set to 10×10 cm2 showed the FWHM of the profile as 7.2 cm, with 3.4 Gy as the maximum DPP and instantaneous dose rate of 8.1E5 Gy/s. Measurements at 100 cm SSD with 10 cm standard cone showed the full width at half max (FWHM) of the profile as 10.5 cm, 1.08 Gy as the maximum DPP and instantaneous dose rate of 2.E5 Gy/s. Machine output with number of pulses was linear (R = 1) from 1 to 99 delivered pulses. Output stability was measured within ±1% within the same session and within ±2% for daily variations. CONCLUSIONS The FLEX conversion of the Clinac is able to generate UHDR electron beams which are reproducible with beam properties similar to clinically used electrons at 16 MeV. Having a platform which can quickly transition between UHDR and conventional modes (<1 min) can be advantageous for future research applications.
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Affiliation(s)
- Ashley J Cetnar
- Department of Radiation Oncology, James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Sagarika Jain
- Department of Radiation Oncology, James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Nilendu Gupta
- Department of Radiation Oncology, James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Arnab Chakravarti
- Department of Radiation Oncology, James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, Ohio, USA
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Ma J, Gao H, Shen X, Bai X, Tang M. A FLASH model of radiolytic oxygen depletion and reactive oxygen species for differential tumor and normal-tissue response. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.10.20.23297337. [PMID: 37961572 PMCID: PMC10635166 DOI: 10.1101/2023.10.20.23297337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Objective FLASH-RT can potentially improve the sparing of normal tissues while preserving the tumoricidal efficiency, owing to the radiation with ultra-high dose rate. However, the FLASH mechanism remains to be solved. A popular FLASH model is based on radiolytic oxygen depletion (ROD), which explains for radiation protection of normal tissues under FLASH-RT. However, ROD does not explain the preservation of tumoricidal efficiency for tumors. This work will develop a ROS+ROD FLASH model that can explain the differential tumor and normal-tissue response. Approach The new FLASH model utilizes reactive oxygen species (ROS) in addition to ROD, and takes into account that ROS level decreases during FLASH-RT. Specifically, the differential-equation model takes into account that the basic ROS level is lower during FLASH-RT and the degeneration rates of ROS are different in tumor cells and healthy cells. Based on this ROS+ROD FLASH model, the surviving fractions of tumor and normal cells are respectively compared between conventional radiotherapy (CONV-RT) and FLASH-RT. Main results While ROD alone does not distinguish the response of tumors and normal tissues to FLASH-RT, the proposed new FLASH model based on ROD and ROS successfully explained the differential response of tumors and normal tissues to FLASH-RT, i.e., the preserved tumoricidal capability, which cannot be explained by ROD alone, and the extra normal-tissue protection owing to the ultra-high dose rate. Significance Since the ROS level decreases slower in tumors than in normal tissues, during FLASH-RT, ROS decreases more in normal tissue, thus can get more protection. By incorporating ROS in addition to ROD, the new FLASH model can not only recover all results by previous FLASH model with ROD alone, but also explain the differential response: preserved lethality of FLASH-RT to tumors and improved protection to normal tissues.
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Affiliation(s)
- Jiangjun Ma
- Institute of Natural Sciences and School of Mathematics, Shanghai Jiao Tong University, Shanghai, China
| | - Hao Gao
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, USA
| | - Xing Shen
- Ruijin hospital proton therapy center Shanghai Jiaotong University School of Medicine
| | - Xuemin Bai
- Mevion Medical Systems, Inc., Kunshan, Jiangsu, China
| | - Min Tang
- Institute of Natural Sciences and School of Mathematics, Shanghai Jiao Tong University, Shanghai, China
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Duval KEA, Aulwes E, Zhang R, Rahman M, Ashraf MR, Sloop A, Sunnerberg J, Williams BB, Cao X, Bruza P, Kheirollah A, Tavakkoli A, Jarvis LA, Schaner PE, Swartz HM, Gladstone DJ, Pogue BW, Hoopes PJ. Comparison of Tumor Control and Skin Damage in a Mouse Model after Ultra-High Dose Rate Irradiation and Conventional Irradiation. Radiat Res 2023; 200:223-231. [PMID: 37590482 PMCID: PMC10551764 DOI: 10.1667/rade-23-00057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 07/07/2023] [Indexed: 08/19/2023]
Abstract
Recent studies suggest ultra-high dose rate radiation treatment (UHDR-RT) reduces normal tissue damage compared to conventional radiation treatment (CONV-RT) at the same dose. In this study, we compared first, the kinetics and degree of skin damage in wild-type C57BL/6 mice, and second, tumor treatment efficacy in GL261 and B16F10 dermal tumor models, at the same UHDR-RT and CONV-RT doses. Flank skin of wild-type mice received UHDR-RT or CONV-RT at 25 Gy and 30 Gy. Normal skin damage was tracked by clinical observation to determine the time to moist desquamation, an endpoint which was verified by histopathology. Tumors were inoculated on the right flank of the mice, then received UHDR-RT or CONV-RT at 1 × 11 Gy, 1 × 15, 1 × 25, 3 × 6 and 3 × 8 Gy, and time to tumor tripling volume was determined. Tumors also received 1 × 11, 1 × 15, 3 × 6 and 3 × 8 Gy doses for assessment of CD8+/CD4+ tumor infiltrate and genetic expression 96 h postirradiation. All irradiations of the mouse tumor or flank skin were performed with megavoltage electron beams (10 MeV, 270 Gy/s for UHDR-RT and 9 MeV, 0.12 Gy/s for CONV-RT) delivered via a clinical linear accelerator. Tumor control was statistically equal for similar doses of UHDR-RT and CONV-RT in B16F10 and GL261 murine tumors. There were variable qualitative differences in genetic expression of immune and cell damage-associated pathways between UHDR and CONV irradiated B16F10 tumors. Compared to CONV-RT, UHDR-RT resulted in an increased latent period to skin desquamation after a single 25 Gy dose (7 days longer). Time to moist skin desquamation did not significantly differ between UHDR-RT and CONV-RT after a 30 Gy dose. The histomorphological characteristics of skin damage were similar for UHDR-RT and CONV-RT. These studies demonstrated similar tumor control responses for equivalent single and fractionated radiation doses, with variable difference in expression of tumor progression and immune related gene pathways. There was a modest UHDR-RT skin sparing effect after a 1 × 25 Gy dose but not after a 1 × 30 Gy dose.
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Affiliation(s)
- Kayla E. A. Duval
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
| | - Ethan Aulwes
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
| | - Rongxiao Zhang
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
| | - Mahbubur Rahman
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - M. Ramish Ashraf
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Austin Sloop
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Jacob Sunnerberg
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Benjamin B. Williams
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
| | - Xu Cao
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Petr Bruza
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | | | - Armin Tavakkoli
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
| | - Lesley A. Jarvis
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
| | - Philip E. Schaner
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
| | - Harold M. Swartz
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
| | - David J. Gladstone
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
| | - Brian W. Pogue
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin
| | - P. Jack Hoopes
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
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Ha B, Liang K, Liu C, Melemenidis S, Manjappa R, Viswanathan V, Das N, Ashraf R, Lau B, Soto L, Graves EE, Rao J, Loo BW, Pratx G. Real-time optical oximetry during FLASH radiotherapy using a phosphorescent nanoprobe. Radiother Oncol 2022; 176:239-243. [PMID: 35964762 PMCID: PMC11277691 DOI: 10.1016/j.radonc.2022.08.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 08/04/2022] [Accepted: 08/07/2022] [Indexed: 12/14/2022]
Abstract
The rapid depletion of oxygen during irradiation at ultra-high dose rate calls for tissue oximeters capable of high temporal resolution. This study demonstrates a water-soluble phosphorescent nanoprobe and fiber-coupled instrument, which together are used to measure the kinetics of oxygen depletion at 200 Hz during irradiation of in vitro solutions.
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Affiliation(s)
- Byunghang Ha
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA; Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Kaitlyn Liang
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA; Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Cheng Liu
- Molecular Imaging Program at Stanford, Departments of Radiology and Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Stavros Melemenidis
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Rakesh Manjappa
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Vignesh Viswanathan
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Neeladrisingha Das
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Ramish Ashraf
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Brianna Lau
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Luis Soto
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Edward E Graves
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Jianghong Rao
- Molecular Imaging Program at Stanford, Departments of Radiology and Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Billy W Loo
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Guillem Pratx
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA.
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11
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Taylor E, Hill RP, Létourneau D. Modeling the impact of spatial oxygen heterogeneity on radiolytic oxygen depletion during FLASH radiotherapy. Phys Med Biol 2022; 67. [PMID: 35576920 DOI: 10.1088/1361-6560/ac702c] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/16/2022] [Indexed: 12/12/2022]
Abstract
Purpose.It has been postulated that the delivery of radiotherapy at ultra-high dose rates ('FLASH') reduces normal tissue toxicities by depleting them of oxygen. The fraction of normal tissue and cancer cells surviving radiotherapy depends on dose and oxygen levels in an exponential manner and even a very small fraction of tissue at low oxygen levels can determine radiotherapy response. To quantify the differential impact of FLASH radiotherapy on normal and tumour tissues, the spatial heterogeneity of oxygenation in tissue should thus be accounted for.Methods.The effect of FLASH on radiation-induced normal and tumour tissue cell killing was studied by simulating oxygen diffusion, metabolism, and radiolytic oxygen depletion (ROD) over domains with simulated capillary architectures. To study the impact of heterogeneity, two architectural models were used: (1) randomly distributed capillaries and (2) capillaries forming a regular square lattice array. The resulting oxygen partial pressure distribution histograms were used to simulate normal and tumour tissue cell survival using the linear quadratic model of cell survival, modified to incorporate oxygen-enhancement ratio effects. The ratio ('dose modifying factors') of conventional low-dose-rate dose and FLASH dose at iso-cell survival was computed and compared with empirical iso-toxicity dose ratios.Results.Tumour cell survival was found to be increased by FLASH as compared to conventional radiotherapy, with a 0-1 order of magnitude increase for expected levels of tumour hypoxia, depending on the relative magnitudes of ROD and tissue oxygen metabolism. Interestingly, for the random capillary model, the impact of FLASH on well-oxygenated (normal) tissues was found to be much greater, with an estimated increase in cell survival by up to 10 orders of magnitude, even though reductions in mean tissue partial pressure were modest, less than ∼7 mmHg for the parameter values studied. The dose modifying factor for normal tissues was found to lie in the range 1.2-1.7 for a representative value of normal tissue oxygen metabolic rate, consistent with preclinical iso-toxicity results.Conclusions.The presence of very small nearly hypoxic regions in otherwise well-perfused normal tissues with high mean oxygen levels resulted in a greater proportional sparing of normal tissue than tumour cells during FLASH irradiation, possibly explaining empirical normal tissue sparing and iso-tumour control results.
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Affiliation(s)
- Edward Taylor
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Richard P Hill
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Daniel Létourneau
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
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12
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Sørensen BS, Sitarz MK, Ankjærgaard C, Johansen JG, Andersen CE, Kanouta E, Grau C, Poulsen P. Pencil beam scanning proton FLASH maintains tumor control while normal tissue damage is reduced in a mouse model. Radiother Oncol 2022; 175:178-184. [PMID: 35595175 DOI: 10.1016/j.radonc.2022.05.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/12/2022] [Accepted: 05/12/2022] [Indexed: 01/16/2023]
Abstract
PURPOSE Preclinical studies indicate a normal tissue sparing effect when ultra-high dose rate (FLASH) radiation is used, while tumor response is maintained. This differential response has promising perspectives for improved clinical outcome. This study investigates tumor control and normal tissue toxicity of pencil beam scanning (PBS) proton FLASH in a mouse model. METHODS AND MATERIALS Tumor bearing hind limbs of non-anaesthetized CDF1 mice were irradiated in a single fraction with a PBS proton beam using either conventional (CONV) dose rate (0.33-0.63 Gy/s field dose rate, 244 MeV) or FLASH (71-89 Gy/s field dose rate, 250 MeV). 162 mice with a C3H mouse mammary carcinoma subcutaneously implanted in the foot were irradiated with physical doses of 40-60 Gy (8-14 mice per dose point). The endpoints were tumor control (TC) assessed as no recurrent tumor at 90 days after treatment, the level of acute moist desquamation (MD) to the skin of the foot within 25 days post irradiation, and radiation induced fibrosis (RIF) within 24 weeks post irradiation. RESULTS TCD50 (dose for 50% tumor control) was similar for CONV and FLASH with values (and 95% confidence intervals) of 49.1 (47.0-51.4) Gy for CONV and 51.3 (48.6-54.2) Gy for FLASH. RIF analysis was restricted to mice with tumor control. Both endpoints showed distinct normal tissue sparing effect of proton FLASH with MDD50 (dose for 50% of mice displaying moist desquamation) of <40.1 Gy for CONV and 52.3 (50.0-54.6) Gy for FLASH, (dose modifying factor at least 1.3) and FD50 (dose for 50% of mice displaying fibrosis) of 48.6 (43.2-50.8) Gy for CONV and 55.6 (52.5-60.1) Gy for FLASH (dose modifying factor of 1.14). CONCLUSIONS FLASH had the same tumor control as CONV, but reduced normal tissue damage assessed as acute skin damage and radiation induced fibrosis.
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Affiliation(s)
- Brita Singers Sørensen
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark; Department of Experimental Clinical Oncology, Aarhus University Hospital, Denmark.
| | | | | | - Jacob G Johansen
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | | | - Eleni Kanouta
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Cai Grau
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Per Poulsen
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark; Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
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13
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Schüler E, Acharya M, Montay-Gruel P, Loo BW, Vozenin MC, Maxim PG. Ultra-high dose rate electron beams and the FLASH effect: From preclinical evidence to a new radiotherapy paradigm. Med Phys 2022; 49:2082-2095. [PMID: 34997969 PMCID: PMC9032195 DOI: 10.1002/mp.15442] [Citation(s) in RCA: 66] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/14/2021] [Accepted: 12/17/2021] [Indexed: 12/30/2022] Open
Abstract
In their seminal paper from 2014, Fauvadon et al. coined the term FLASH irradiation to describe ultra-high-dose rate irradiation with dose rates greater than 40 Gy/s, which results in delivery times of fractions of a second. The experiments presented in that paper were performed with a high-dose-per-pulse 4.5 MeV electron beam, and the results served as the basis for the modern-day field of FLASH radiation therapy (RT). In this article, we review the studies that have been published after those early experiments, demonstrating the robust effects of FLASH RT on normal tissue sparing in preclinical models. We also outline the various irradiation parameters that have been used. Although the robustness of the biological response has been established, the mechanisms behind the FLASH effect are currently under investigation in a number of laboratories. However, differences in the magnitude of the FLASH effect between experiments in different labs have been reported. Reasons for these differences even within the same animal model are currently unknown, but likely has to do with the marked differences in irradiation parameter settings used. Here, we show that these parameters are often not reported, which complicates large multistudy comparisons. For this reason, we propose a new standard for beam parameter reporting and discuss a systematic path to the clinical translation of FLASH RT.
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Affiliation(s)
- Emil Schüler
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030 USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, TX 77030 USA
| | - Munjal Acharya
- Department of Anatomy and Neurobiology, University of California Irvine, Irvine, CA, USA
| | - Pierre Montay-Gruel
- Department of Radiation Oncology, University of California Irvine, Irvine, CA, USA
| | - Billy W. Loo
- Department of Radiation Oncology and Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Marie-Catherine Vozenin
- Laboratory of Radiation Oncology/DO/Radio-Oncology/CHUV, Lausanne University Hospital and University of Lausanne, 1011 Lausanne, Switzerland
| | - Peter G. Maxim
- Department of Radiation Oncology, University of California Irvine, Irvine, CA, USA
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14
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Okoro CM, Schüler E, Taniguchi CM. The Therapeutic Potential of FLASH-RT for Pancreatic Cancer. Cancers (Basel) 2022; 14:cancers14051167. [PMID: 35267474 PMCID: PMC8909276 DOI: 10.3390/cancers14051167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 11/21/2022] Open
Abstract
Simple Summary Ultra-high dose rate radiation, widely nicknamed FLASH-RT, kills tumors without significantly damaging nearby normal tissues. This selective sparing of normal tissue by FLASH-RT tissue is called the FLASH effect. This review explores some of the proposed mechanisms of the FLASH effect and the current data that might support its use in pancreatic cancer. Since radiation for pancreatic cancer treatment is limited by GI toxicity issues and is a disease with one of the lowest five-year survival rates, FLASH-RT could have a large impact in the treatment of this disease with further study. Abstract Recent preclinical evidence has shown that ionizing radiation given at an ultra-high dose rate (UHDR), also known as FLASH radiation therapy (FLASH-RT), can selectively reduce radiation injury to normal tissue while remaining isoeffective to conventional radiation therapy (CONV-RT) with respect to tumor killing. Unresectable pancreatic cancer is challenging to control without ablative doses of radiation, but this is difficult to achieve without significant gastrointestinal toxicity. In this review article, we explore the propsed mechanisms of FLASH-RT and its tissue-sparing effect, as well as its relevance and suitability for the treatment of pancreatic cancer. We also briefly discuss the challenges with regard to dosimetry, dose rate, and fractionation for using FLASH-RT to treat this disease.
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Affiliation(s)
- Chidi M. Okoro
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA;
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Emil Schüler
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Correspondence: (E.S.); (C.M.T.)
| | - Cullen M. Taniguchi
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA;
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Correspondence: (E.S.); (C.M.T.)
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15
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Ruan JL, Lee C, Wouters S, Tullis IDC, Verslegers M, Mysara M, Then CK, Smart SC, Hill MA, Muschel RJ, Giaccia AJ, Vojnovic B, Kiltie AE, Petersson K. Irradiation at Ultra-High (FLASH) Dose Rates Reduces Acute Normal Tissue Toxicity in the Mouse Gastrointestinal System. Int J Radiat Oncol Biol Phys 2021; 111:1250-1261. [PMID: 34400268 PMCID: PMC7612009 DOI: 10.1016/j.ijrobp.2021.08.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 12/18/2022]
Abstract
PURPOSE Preclinical studies using ultra-high dose rate (FLASH) irradiation have demonstrated reduced normal tissue toxicity compared with conventional dose rate (CONV) irradiation, although this finding is not universal. We investigated the effect of temporal pulse structure and average dose rate of FLASH compared with CONV irradiation on acute intestinal toxicity. MATERIALS AND METHODS Whole abdomens of C3H mice were irradiated with a single fraction to various doses, using a 6 MeV electron linear accelerator with single pulse FLASH (dose rate = 2-6 × 106 Gy/s) or conventional (CONV; 0.25 Gy/s) irradiation. At 3.75 days postirradiation, fresh feces were collected for 16S rRNA sequencing to assess changes in the gut microbiota. A Swiss roll-based crypt assay was used to quantify acute damage to the intestinal crypts to determine how tissue toxicity was affected by the different temporal pulse structures of FLASH delivery. RESULTS We found statistically significant improvements in crypt survival for mice irradiated with FLASH at doses between 7.5 and 12.5 Gy, with a dose modifying factor of 1.1 for FLASH (7.5 Gy, P < .01; 10 Gy, P < .05; 12.5 Gy, P < .01). This sparing effect was lost when the delivery time was increased, either by increasing the number of irradiation pulses or by prolonging the time between 2 successive pulses. Sparing was observed for average dose rates of ≥280 Gy/s. Fecal microbiome analysis showed that FLASH irradiation caused fewer changes to the microbiota than CONV irradiation. CONCLUSIONS This study demonstrates that FLASH irradiation can spare mouse small intestinal crypts and reduce changes in gut microbiome composition compared with CONV irradiation. The higher the average dose rate, the larger the FLASH effect, which is also influenced by temporal pulse structure of the delivery.
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Affiliation(s)
- Jia-Ling Ruan
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Carl Lee
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Science, University of Oxford, Oxford, United Kingdom
| | - Shari Wouters
- Interdisciplinary Biosciences Group, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium; Molecular Pathology Group, Cell Biology and Histology and Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, Campus Drie Eiken, University of Antwerp, Antwerp, Belgium
| | - Iain D C Tullis
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Mieke Verslegers
- Interdisciplinary Biosciences Group, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Mohamed Mysara
- Interdisciplinary Biosciences Group, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Chee Kin Then
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Sean C Smart
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Mark A Hill
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Ruth J Muschel
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Amato J Giaccia
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Borivoj Vojnovic
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Anne E Kiltie
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Kristoffer Petersson
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom; Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden.
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16
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Ronga MG, Cavallone M, Patriarca A, Leite AM, Loap P, Favaudon V, Créhange G, De Marzi L. Back to the Future: Very High-Energy Electrons (VHEEs) and Their Potential Application in Radiation Therapy. Cancers (Basel) 2021; 13:4942. [PMID: 34638424 PMCID: PMC8507836 DOI: 10.3390/cancers13194942] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 12/14/2022] Open
Abstract
The development of innovative approaches that would reduce the sensitivity of healthy tissues to irradiation while maintaining the efficacy of the treatment on the tumor is of crucial importance for the progress of the efficacy of radiotherapy. Recent methodological developments and innovations, such as scanned beams, ultra-high dose rates, and very high-energy electrons, which may be simultaneously available on new accelerators, would allow for possible radiobiological advantages of very short pulses of ultra-high dose rate (FLASH) therapy for radiation therapy to be considered. In particular, very high-energy electron (VHEE) radiotherapy, in the energy range of 100 to 250 MeV, first proposed in the 2000s, would be particularly interesting both from a ballistic and biological point of view for the establishment of this new type of irradiation technique. In this review, we examine and summarize the current knowledge on VHEE radiotherapy and provide a synthesis of the studies that have been published on various experimental and simulation works. We will also consider the potential for VHEE therapy to be translated into clinical contexts.
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Affiliation(s)
- Maria Grazia Ronga
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
- Thales AVS Microwave & Imaging Sub-Systems, 78141 Vélizy-Villacoublay, France
| | - Marco Cavallone
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
| | - Annalisa Patriarca
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
| | - Amelia Maia Leite
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
- INSERM LITO U1288, Campus Universitaire, Institut Curie, PSL Research University, University Paris Saclay, 91898 Orsay, France
| | - Pierre Loap
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
| | - Vincent Favaudon
- INSERM U 1021-CNRS UMR 3347, Campus Universitaire, Institut Curie, PSL Research University, University Paris Saclay, 91898 Orsay, France;
| | - Gilles Créhange
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
| | - Ludovic De Marzi
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
- INSERM LITO U1288, Campus Universitaire, Institut Curie, PSL Research University, University Paris Saclay, 91898 Orsay, France
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17
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Can Rational Combination of Ultra-high Dose Rate FLASH Radiotherapy with Immunotherapy Provide a Novel Approach to Cancer Treatment? Clin Oncol (R Coll Radiol) 2021; 33:713-722. [PMID: 34551871 DOI: 10.1016/j.clon.2021.09.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/30/2021] [Accepted: 09/03/2021] [Indexed: 12/23/2022]
Abstract
FLASH radiotherapy (FLASH-RT) delivers radiation treatment at an ultra-high dose rate that is several orders of magnitude higher than current clinical practice. In multiple preclinical studies, FLASH-RT has shown consistent normal tissue sparing effects while preserving equivalent antitumour activity in comparison with conventional dose rate radiation treatment. This is known as the 'FLASH effect'. Given the recent research interest in combining hypofractionated radiotherapy with immunotherapy to try to improve clinical outcomes, there is an intriguing clinical question as to whether FLASH irradiation may be a rational partner to combine with immune modulating drugs? To better predict the synergistic effect of both modalities, here we review the biological mechanisms of how FLASH differentially impacts the immune landscape, including circulating immune cells, tumour microenvironment and the inflammatory response. In order to make recommendations for future research, we summarise all published studies that investigated the immune modulatory effects of FLASH-RT and further explore the scientific reasons for combining FLASH with immunotherapy for potential clinical applications.
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18
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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] [MESH Headings] [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.
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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.
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19
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Cunningham S, McCauley S, Vairamani K, Speth J, Girdhani S, Abel E, Sharma RA, Perentesis JP, Wells SI, Mascia A, Sertorio M. FLASH Proton Pencil Beam Scanning Irradiation Minimizes Radiation-Induced Leg Contracture and Skin Toxicity in Mice. Cancers (Basel) 2021; 13:cancers13051012. [PMID: 33804336 PMCID: PMC7957631 DOI: 10.3390/cancers13051012] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/18/2021] [Accepted: 02/22/2021] [Indexed: 02/07/2023] Open
Abstract
Simple Summary Dose and efficacy of radiation therapy are limited by the toxicity to normal tissue adjacent to the treated tumor region. Recently, ultra-high dose rate radiotherapy (FLASH radiotherapy) has shown beneficial reduction of normal tissue damage while preserving similar tumor efficacy with electron, photon and scattered proton beam irradiation in preclinical models. Proton therapy is increasingly delivered by pencil beam scanning (PBS) technology, and we therefore set out to test PBS FLASH radiotherapy on normal tissue toxicity and tumor control in vivo in mouse using a clinical proton delivery system. This validation of the FLASH normal tissue-sparing hypothesis with a clinical delivery system provides supporting data for PBS FLASH radiotherapy and its potential role in improving radiotherapy outcomes. Abstract Ultra-high dose rate radiation has been reported to produce a more favorable toxicity and tumor control profile compared to conventional dose rates that are used for patient treatment. So far, the so-called FLASH effect has been validated for electron, photon and scattered proton beam, but not yet for proton pencil beam scanning (PBS). Because PBS is the state-of-the-art delivery modality for proton therapy and constitutes a wide and growing installation base, we determined the benefit of FLASH PBS on skin and soft tissue toxicity. Using a pencil beam scanning nozzle and the plateau region of a 250 MeV proton beam, a uniform physical dose of 35 Gy (toxicity study) or 15 Gy (tumor control study) was delivered to the right hind leg of mice at various dose rates: Sham, Conventional (Conv, 1 Gy/s), Flash60 (57 Gy/s) and Flash115 (115 Gy/s). Acute radiation effects were quantified by measurements of plasma and skin levels of TGF-β1 and skin toxicity scoring. Delayed irradiation response was defined by hind leg contracture as a surrogate of irradiation-induced skin and soft tissue toxicity and by plasma levels of 13 different cytokines (CXCL1, CXCL10, Eotaxin, IL1-beta, IL-6, MCP-1, Mip1alpha, TNF-alpha, TNF-beta, VEGF, G-CSF, GM-CSF and TGF- β1). Plasma and skin levels of TGF-β1, skin toxicity and leg contracture were all significantly decreased in FLASH compared to Conv groups of mice. FLASH and Conv PBS had similar efficacy with regards to growth control of MOC1 and MOC2 head and neck cancer cells transplanted into syngeneic, immunocompetent mice. These results demonstrate consistent delivery of FLASH PBS radiation from 1 to 115 Gy/s in a clinical gantry. Radiation response following delivery of 35 Gy indicates potential benefits of FLASH versus conventional PBS that are related to skin and soft tissue toxicity.
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Affiliation(s)
- Shannon Cunningham
- Cincinnati Children’s Hospital Medical Center, Division of Oncology, Cincinnati, OH 45229, USA; (S.C.); (S.M.); (K.V.); (J.P.P.); (S.I.W.)
| | - Shelby McCauley
- Cincinnati Children’s Hospital Medical Center, Division of Oncology, Cincinnati, OH 45229, USA; (S.C.); (S.M.); (K.V.); (J.P.P.); (S.I.W.)
| | - Kanimozhi Vairamani
- Cincinnati Children’s Hospital Medical Center, Division of Oncology, Cincinnati, OH 45229, USA; (S.C.); (S.M.); (K.V.); (J.P.P.); (S.I.W.)
| | - Joseph Speth
- Department of Radiation Oncology, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA; (J.S.); (A.M.)
| | - Swati Girdhani
- Varian Medical Systems, Inc., Palo Alto, CA 94304, USA; (S.G.); (E.A.); (R.A.S.)
| | - Eric Abel
- Varian Medical Systems, Inc., Palo Alto, CA 94304, USA; (S.G.); (E.A.); (R.A.S.)
| | - Ricky A. Sharma
- Varian Medical Systems, Inc., Palo Alto, CA 94304, USA; (S.G.); (E.A.); (R.A.S.)
| | - John P. Perentesis
- Cincinnati Children’s Hospital Medical Center, Division of Oncology, Cincinnati, OH 45229, USA; (S.C.); (S.M.); (K.V.); (J.P.P.); (S.I.W.)
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Susanne I. Wells
- Cincinnati Children’s Hospital Medical Center, Division of Oncology, Cincinnati, OH 45229, USA; (S.C.); (S.M.); (K.V.); (J.P.P.); (S.I.W.)
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Anthony Mascia
- Department of Radiation Oncology, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA; (J.S.); (A.M.)
| | - Mathieu Sertorio
- Cincinnati Children’s Hospital Medical Center, Division of Oncology, Cincinnati, OH 45229, USA; (S.C.); (S.M.); (K.V.); (J.P.P.); (S.I.W.)
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
- Correspondence:
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Mazal A, Prezado Y, Ares C, de Marzi L, Patriarca A, Miralbell R, Favaudon V. FLASH and minibeams in radiation therapy: the effect of microstructures on time and space and their potential application to protontherapy. Br J Radiol 2020; 93:20190807. [PMID: 32003574 PMCID: PMC7066940 DOI: 10.1259/bjr.20190807] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
After years of lethargy, studies on two non-conventional microstructures in time and space of the beams used in radiation therapy are enjoying a huge revival. The first effect called “FLASH” is based on very high dose-rate irradiation (pulse amplitude ≥106 Gy/s), short beam-on times (≤100 ms) and large single doses (≥10 Gy) as experimental parameters established so far to give biological and potential clinical effects. The second effect relies on the use of arrays of minibeams (e.g., 0.5–1 mm, spaced 1–3.5 mm). Both approaches have been shown to protect healthy tissues as an endpoint that must be clearly specified and could be combined with each other (e.g., minibeams under FLASH conditions). FLASH depends on the presence of oxygen and could proceed from the chemistry of peroxyradicals and a reduced incidence on DNA and membrane damage. Minibeams action could be based on abscopal effects, cell signalling and/or migration of cells between “valleys and hills” present in the non-uniform irradiation field as well as faster repair of vascular damage. Both effects are expected to maintain intact the tumour control probability and might even preserve antitumoural immunological reactions. FLASH in vivo experiments involving Zebrafish, mice, pig and cats have been done with electron beams, while minibeams are an intermediate approach between X-GRID and synchrotron X-ray microbeams radiation. Both have an excellent rationale to converge and be applied with proton beams, combining focusing properties and high dose rates in the beam path of pencil beams, and the inherent advantage of a controlled limited range. A first treatment with electron FLASH (cutaneous lymphoma) has recently been achieved, but clinical trials have neither been presented for FLASH with protons, nor under the minibeam conditions. Better understanding of physical, chemical and biological mechanisms of both effects is essential to optimize the technical developments and devise clinical trials.
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Affiliation(s)
| | - Yolanda Prezado
- IMNC, University Paris-Sud and Paris-Saclay, CNRS/IN2P3, Orsay, France
| | - Carme Ares
- Centro de Protonterapia Quironsalud, Madrid, Spain
| | - Ludovic de Marzi
- Institut Curie, Institut Curie, PSL Research University, Centre de protonthérapie d'Orsay, Campus universitaire, bâtiment 101, Orsay 91898, France.,Institut Curie, Inserm U 1021-CNRS UMR 3347, Paris-Saclay and PSL Research Universities, Orsay, France
| | - Annalisa Patriarca
- Institut Curie, Institut Curie, PSL Research University, Centre de protonthérapie d'Orsay, Campus universitaire, bâtiment 101, Orsay 91898, France
| | | | - Vincent Favaudon
- Institut Curie, Inserm U 1021-CNRS UMR 3347, Paris-Saclay and PSL Research Universities, Orsay, France
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Wilson JD, Hammond EM, Higgins GS, Petersson K. Ultra-High Dose Rate (FLASH) Radiotherapy: Silver Bullet or Fool's Gold? Front Oncol 2020; 9:1563. [PMID: 32010633 PMCID: PMC6979639 DOI: 10.3389/fonc.2019.01563] [Citation(s) in RCA: 255] [Impact Index Per Article: 63.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 12/24/2019] [Indexed: 12/12/2022] Open
Abstract
Radiotherapy is a cornerstone of both curative and palliative cancer care. However, radiotherapy is severely limited by radiation-induced toxicities. If these toxicities could be reduced, a greater dose of radiation could be given therefore facilitating a better tumor response. Initial pre-clinical studies have shown that irradiation at dose rates far exceeding those currently used in clinical contexts reduce radiation-induced toxicities whilst maintaining an equivalent tumor response. This is known as the FLASH effect. To date, a single patient has been subjected to FLASH radiotherapy for the treatment of subcutaneous T-cell lymphoma resulting in complete response and minimal toxicities. The mechanism responsible for reduced tissue toxicity following FLASH radiotherapy is yet to be elucidated, but the most prominent hypothesis so far proposed is that acute oxygen depletion occurs within the irradiated tissue. This review examines the tissue response to FLASH radiotherapy, critically evaluates the evidence supporting hypotheses surrounding the biological basis of the FLASH effect, and considers the potential for FLASH radiotherapy to be translated into clinical contexts.
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Affiliation(s)
- Joseph D. Wilson
- Department of Oncology, The Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Ester M. Hammond
- Department of Oncology, The Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Geoff S. Higgins
- Department of Oncology, The Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Kristoffer Petersson
- Department of Oncology, The Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
- Radiation Physics, Department of Haematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
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Comparative toxicity of synchrotron and conventional radiation therapy based on total and partial body irradiation in a murine model. Sci Rep 2018; 8:12044. [PMID: 30104646 PMCID: PMC6089899 DOI: 10.1038/s41598-018-30543-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 07/30/2018] [Indexed: 11/09/2022] Open
Abstract
Synchrotron radiation can facilitate novel radiation therapy modalities such as microbeam radiation therapy (MRT) and high dose-rate synchrotron broad-beam radiation therapy (SBBR). Both of these modalities have unique physical properties that could be exploited for an improved therapeutic effect. While pre-clinical studies report promising normal tissue sparing phenomena, systematic toxicity data are still required. Our objective was to characterise the toxicity of SBBR and MRT and to calculate equivalent doses of conventional radiation therapy (CRT). A dose-escalation study was performed on C57BLJ/6 mice using total body and partial body irradiations. Dose-response curves and TD50 values were subsequently calculated using PROBIT analysis. For SBBR at dose-rates of 37 to 41 Gy/s, we found no evidence of a normal tissue sparing effect relative to CRT. Our findings also show that the MRT valley dose, rather than the peak dose, best correlates with CRT doses for acute toxicity. Importantly, longer-term weight tracking of irradiated animals revealed more pronounced growth impairment following MRT compared to both SBBR and CRT. Overall, this study provides the first in vivo dose-equivalence data between MRT, SBBR and CRT and presents systematic toxicity data for a range of organs that can be used as a reference point for future pre-clinical work.
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