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Fu J, Yang Z, Melemenidis S, Viswanathan V, Dutt S, Manjappa R, Lau B, Soto LA, Ashraf MR, Skinner L, Yu SJ, Surucu M, Casey KM, Rankin EB, Graves E, Lu W, Loo BW, Gu X. Exploring Deep Learning for Estimating the Isoeffective Dose of FLASH Irradiation From Mouse Intestinal Histological Images. Int J Radiat Oncol Biol Phys 2024; 119:1001-1010. [PMID: 38171387 DOI: 10.1016/j.ijrobp.2023.12.032] [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: 07/05/2023] [Revised: 12/09/2023] [Accepted: 12/23/2023] [Indexed: 01/05/2024]
Abstract
PURPOSE Ultrahigh-dose-rate (FLASH) irradiation has been reported to reduce normal tissue damage compared with conventional dose rate (CONV) irradiation without compromising tumor control. This proof-of-concept study aims to develop a deep learning (DL) approach to quantify the FLASH isoeffective dose (dose of CONV that would be required to produce the same effect as the given physical FLASH dose) with postirradiation mouse intestinal histology images. METHODS AND MATERIALS Eighty-four healthy C57BL/6J female mice underwent 16 MeV electron CONV (0.12 Gy/s; n = 41) or FLASH (200 Gy/s; n = 43) single fraction whole abdominal irradiation. Physical dose ranged from 12 to 16 Gy for FLASH and 11 to 15 Gy for CONV in 1 Gy increments. Four days after irradiation, 9 jejunum cross-sections from each mouse were hematoxylin and eosin stained and digitized for histological analysis. CONV data set was randomly split into training (n = 33) and testing (n = 8) data sets. ResNet101-based DL models were retrained using the CONV training data set to estimate the dose based on histological features. The classical manual crypt counting (CC) approach was implemented for model comparison. Cross-section-wise mean squared error was computed to evaluate the dose estimation accuracy of both approaches. The validated DL model was applied to the FLASH data set to map the physical FLASH dose into the isoeffective dose. RESULTS The DL model achieved a cross-section-wise mean squared error of 0.20 Gy2 on the CONV testing data set compared with 0.40 Gy2 of the CC approach. Isoeffective doses estimated by the DL model for FLASH doses of 12, 13, 14, 15, and 16 Gy were 12.19 ± 0.46, 12.54 ± 0.37, 12.69 ± 0.26, 12.84 ± 0.26, and 13.03 ± 0.28 Gy, respectively. CONCLUSIONS Our proposed DL model achieved accurate CONV dose estimation. The DL model results indicate that in the physical dose range of 13 to 16 Gy, the biologic dose response of small intestinal tissue to FLASH irradiation is represented by a lower isoeffective dose compared with the physical dose. Our DL approach can be a tool for studying isoeffective doses of other radiation dose modifying interventions.
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Affiliation(s)
- Jie Fu
- Department of Radiation Oncology, University of Washington, Seattle, Washington; Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Zi Yang
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California; Medical Artificial Intelligence and Automation (MAIA) Laboratory, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Stavros Melemenidis
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Vignesh Viswanathan
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Suparna Dutt
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Rakesh Manjappa
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Brianna Lau
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Luis A Soto
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - M Ramish Ashraf
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Lawrie Skinner
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Shu-Jung Yu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Murat Surucu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Kerriann M Casey
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford, California
| | - Erinn B Rankin
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Edward Graves
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Weiguo Lu
- Medical Artificial Intelligence and Automation (MAIA) Laboratory, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Billy W Loo
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California.
| | - Xuejun Gu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California.
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Kyle AH, Karan T, Baker JHE, Püspöky Banáth J, Wang T, Liu A, Mendez C, Peter Petric M, Duzenli C, Minchinton AI. Detection of FLASH-radiotherapy tissue sparing in a 3D-spheroid model using DNA damage response markers. Radiother Oncol 2024; 196:110326. [PMID: 38735536 DOI: 10.1016/j.radonc.2024.110326] [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: 11/20/2023] [Revised: 04/07/2024] [Accepted: 04/28/2024] [Indexed: 05/14/2024]
Abstract
PURPOSE The oxygen depletion hypothesis has been proposed as a rationale to explain the observed phenomenon of FLASH-radiotherapy (FLASH-RT) sparing normal tissues while simultaneously maintaining tumor control. In this study we examined the distribution of DNA Damage Response (DDR) markers in irradiated 3D multicellular spheroids to explore the relationship between FLASH-RT protection and radiolytic-oxygen-consumption (ROC) in tissues. METHODS Studies were performed using a Varian Truebeam linear accelerator delivering 10 MeV electrons with an average dose rate above 50 Gy/s. Irradiations were carried out on 3D spheroids maintained under a range of O2 and temperature conditions to control O2 consumption and create gradients representative of in vivo tissues. RESULTS Staining for pDNA-PK (Ser2056) produced a linear radiation dose response whereas γH2AX (Ser139) showed saturation with increasing dose. Using the pDNA-PK staining, radiation response was then characterised for FLASH compared to standard-dose-rates as a function of depth into the spheroids. At 4 °C, chosen to minimize the development of metabolic oxygen gradients within the tissues, FLASH protection could be observed at all distances under oxygen conditions of 0.3-1 % O2. Whereas at 37 °C a FLASH-protective effect was limited to the outer cell layers of tissues, an effect only observed at 3 % O2. Modelling of changes in the pDNA-PK-based oxygen enhancement ratio (OER) yielded a tissue ROC g0-value estimate of 0.73 ± 0.25 µM/Gy with a km of 5.4 µM at FLASH dose rates. CONCLUSIONS DNA damage response markers are sensitive to the effects of transient oxygen depletion during FLASH radiotherapy. Findings support the rationale that well-oxygenated tissues would benefit more from FLASH-dose-rate protection relative to poorly-oxygenated tissues.
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Affiliation(s)
| | | | | | | | | | - Anam Liu
- BC Cancer Research Institute, Vancouver, Canada
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Loo BW, Verginadis II, Sørensen BS, Mascia AE, Perentesis JP, Koong AC, Schüler E, Rankin EB, Maxim PG, Limoli CL, Vozenin MC. Navigating the Critical Translational Questions for Implementing FLASH in the Clinic. Semin Radiat Oncol 2024; 34:351-364. [PMID: 38880544 DOI: 10.1016/j.semradonc.2024.04.008] [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: 06/18/2024]
Abstract
The "FLASH effect" is an increased therapeutic index, that is, reduced normal tissue toxicity for a given degree of anti-cancer efficacy, produced by ultra-rapid irradiation delivered on time scales orders of magnitude shorter than currently conventional in the clinic for the same doses. This phenomenon has been observed in numerous preclinical in vivo tumor and normal tissue models. While the underlying biological mechanism(s) remain to be elucidated, a path to clinical implementation of FLASH can be paved by addressing several critical translational questions. Technological questions pertinent to each beam type (eg, electron, proton, photon) also dictate the logical progression of experimentation required to move forward in safe and decisive clinical trials. Here we review the available preclinical data pertaining to these questions and how they may inform strategies for FLASH cancer therapy clinical trials.
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Affiliation(s)
- Billy W Loo
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA.
| | - Ioannis I Verginadis
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Brita Singers Sørensen
- Danish Centre for Particle Therapy & Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Anthony E Mascia
- Division of Oncology, Cincinnati Children's Hospital and Departments of Pediatrics and Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, OH
| | - John P Perentesis
- Division of Oncology, Cincinnati Children's Hospital and Departments of Pediatrics and Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, OH
| | - Albert C Koong
- Department of Radiation Oncology, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Emil Schüler
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Erinn B Rankin
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA; Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA
| | - Peter G Maxim
- Department of Radiation Oncology, University of California, Irvine School of Medicine, Irvine, CA
| | - Charles L Limoli
- Department of Radiation Oncology, University of California, Irvine School of Medicine, Irvine, CA
| | - Marie-Catherine Vozenin
- Secteur Radio-Oncologie et Radiobiologie, Hôpitaux Universitaires de Genève, Geneva, Switzerland; LiRR - laboratory of innovation in radiobiology applied to radiotherapy, Faculty of Medicine, University of Geneva, Geneva, Switzerland; Laboratory of Radiation Oncology, Radiation Oncology Service, Department of Oncology, CHUV Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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Liu K, Holmes S, Schüler E, Beddar S. A comprehensive investigation of the performance of a commercial scintillator system for applications in electron FLASH radiotherapy. Med Phys 2024; 51:4504-4512. [PMID: 38507253 PMCID: PMC11147715 DOI: 10.1002/mp.17030] [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: 07/21/2023] [Revised: 02/08/2024] [Accepted: 03/04/2024] [Indexed: 03/22/2024] Open
Abstract
BACKGROUND Dosimetry in ultra-high dose rate (UHDR) beamlines is significantly challenged by limitations in real-time monitoring and accurate measurement of beam output, beam parameters, and delivered doses using conventional radiation detectors, which exhibit dependencies in ultra-high dose-rate (UHDR) and high dose-per-pulse (DPP) beamline conditions. PURPOSE In this study, we characterized the response of the Exradin W2 plastic scintillator (Standard Imaging, Inc.), a water-equivalent detector that provides measurements with a time resolution of 100 Hz, to determine its feasibility for use in UHDR electron beamlines. METHODS The W2 scintillator was exposed to an UHDR electron beam with different beam parameters by varying the pulse repetition frequency (PRF), pulse width (PW), and pulse amplitude settings of an electron UHDR linear accelerator system. The response of the W2 scintillator was evaluated as a function of the total integrated dose delivered, DPP, and mean and instantaneous dose rate. To account for detector radiation damage, the signal sensitivity (pC/Gy) of the W2 scintillator was measured and tracked as a function of dose history. RESULTS The W2 scintillator demonstrated mean dose rate independence and linearity as a function of integrated dose and DPP for DPP ≤ 1.5 Gy (R2 > 0.99) and PRF ≤ 90 Hz. At DPP > 1.5 Gy, nonlinear behavior and signal saturation in the blue and green signals as a function of DPP, PRF, and integrated dose became apparent. In the absence of Cerenkov correction, the W2 scintillator exhibited PW dependence, even at DPP values <1.5 Gy, with a difference of up to 31% and 54% in the measured blue and green signal for PWs ranging from 0.5 to 3.6 µs. The change in signal sensitivity of the W2 scintillator as a function of accumulated dose was approximately 4%/kGy and 0.3%/kGy for the measured blue and green signal responses, respectively, as a function of integrated dose history. CONCLUSION The Exradin W2 scintillator can provide output measurements that are both dose rate independent and linear in response if the DPP is kept ≤1.5 Gy (corresponding to a mean dose rate up to 290 Gy/s in the used system), as long as proper calibration is performed to account for PW and changes in signal sensitivity as a function of accumulated dose. For DPP > 1.5 Gy, the W2 scintillator's response becomes nonlinear, likely due to limitations in the electrometer related to the high signal intensity.
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Affiliation(s)
- Kevin Liu
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- UTHealth Houston Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | | | - Emil Schüler
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- UTHealth Houston Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Sam Beddar
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- UTHealth Houston Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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Böhlen TT, Germond JF, Desorgher L, Veres I, Bratel A, Landström E, Engwall E, Herrera FG, Ozsahin EM, Bourhis J, Bochud F, Moeckli R. Very high-energy electron therapy as light-particle alternative to transmission proton FLASH therapy - An evaluation of dosimetric performances. Radiother Oncol 2024; 194:110177. [PMID: 38378075 DOI: 10.1016/j.radonc.2024.110177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/29/2024] [Accepted: 02/16/2024] [Indexed: 02/22/2024]
Abstract
PURPOSE Clinical translation of FLASH-radiotherapy (RT) to deep-seated tumours is still a technological challenge. One proposed solution consists of using ultra-high dose rate transmission proton (TP) beams of about 200-250 MeV to irradiate the tumour with the flat entrance of the proton depth-dose profile. This work evaluates the dosimetric performance of very high-energy electron (VHEE)-based RT (50-250 MeV) as a potential alternative to TP-based RT for the clinical transfer of the FLASH effect. METHODS Basic physics characteristics of VHEE and TP beams were compared utilizing Monte Carlo simulations in water. A VHEE-enabled research treatment planning system was used to evaluate the plan quality achievable with VHEE beams of different energies, compared to 250 MeV TP beams for a glioblastoma, an oesophagus, and a prostate cancer case. RESULTS Like TP, VHEE above 100 MeV can treat targets with roughly flat (within ± 20 %) depth-dose distributions. The achievable dosimetric target conformity and adjacent organs-at-risk (OAR) sparing is consequently driven for both modalities by their lateral beam penumbrae. Electron beams of 400[500] MeV match the penumbra of 200[250] MeV TP beams and penumbra is increased for lower electron energies. For the investigated patient cases, VHEE plans with energies of 150 MeV and above achieved a dosimetric plan quality comparable to that of 250 MeV TP plans. For the glioblastoma and the oesophagus case, although having a decreased conformity, even 100 MeV VHEE plans provided a similar target coverage and OAR sparing compared to TP. CONCLUSIONS VHEE-based FLASH-RT using sufficiently high beam energies may provide a lighter-particle alternative to TP-based FLASH-RT with comparable dosimetric plan quality.
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Affiliation(s)
- Till Tobias Böhlen
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Jean-François Germond
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Laurent Desorgher
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Izabella Veres
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | | | | | | | - Fernanda G Herrera
- Department of Radiation Oncology, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Esat Mahmut Ozsahin
- Department of Radiation Oncology, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Jean Bourhis
- Department of Radiation Oncology, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - François Bochud
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland.
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Liu K, Waldrop T, Aguilar E, Mims N, Neill D, Delahoussaye A, Li Z, Swanson D, Lin SH, Koong AC, Taniguchi CM, Loo BW, Mitra D, Schüler E. Redefining FLASH RT: the impact of mean dose rate and dose per pulse in the gastrointestinal tract. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.19.590158. [PMID: 38712109 PMCID: PMC11071383 DOI: 10.1101/2024.04.19.590158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Background The understanding of how varying radiation beam parameter settings affect the induction and magnitude of the FLASH effect remains limited. Purpose We sought to evaluate how the magnitude of radiation-induced gastrointestinal (GI) toxicity (RIGIT) depends on the interplay between mean dose rate (MDR) and dose per pulse (DPP). Methods C57BL/6J mice were subjected to total abdominal irradiation (11-14 Gy single fraction) under conventional irradiation (low DPP and low MDR, CONV) and various combinations of DPP and MDR up to ultra-high-dose-rate (UHDR) beam conditions. The effects of DPP were evaluated for DPPs of 1-6 Gy while the total dose and MDR were kept constant; the effects of MDR were evaluated for the range 0.3- 1440 Gy/s while the total dose and DPP were kept constant. RIGIT was quantified in non-tumor-bearing mice through the regenerating crypt assay and survival assessment. Tumor response was evaluated through tumor growth delay. Results Within each tested total dose using a constant MDR (>100 Gy/s), increasing DPP led to better sparing of regenerating crypts, with a more prominent effect seen at 12 and 14 Gy TAI. However, at fixed DPPs >4 Gy, similar sparing of crypts was demonstrated irrespective of MDR (from 0.3 to 1440 Gy/s). At a fixed high DPP of 4.7 Gy, survival was equivalently improved relative to CONV for all MDRs from 0.3 Gy/s to 104 Gy/s, but at a lower DPP of 0.93 Gy, increasing MDR produced a greater survival effect. We also confirmed that high DPP, regardless of MDR, produced the same magnitude of tumor growth delay relative to CONV using a clinically relevant melanoma mouse model. Conclusions This study demonstrates the strong influence that the beam parameter settings have on the magnitude of the FLASH effect. Both high DPP and UHDR appeared independently sufficient to produce FLASH sparing of GI toxicity, while isoeffective tumor response was maintained across all conditions.
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Dai T, Sloop AM, Rahman MR, Sunnerberg JP, Clark MA, Young R, Adamczyk S, Von Voigts-Rhetz P, Patane C, Turk M, Jarvis L, Pogue BW, Gladstone DJ, Bruza P, Zhang R. First Monte Carlo beam model for ultra-high dose rate radiotherapy with a compact electron LINAC. Med Phys 2024. [PMID: 38493501 DOI: 10.1002/mp.17031] [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: 09/21/2023] [Revised: 03/04/2024] [Accepted: 03/04/2024] [Indexed: 03/19/2024] Open
Abstract
BACKGROUND FLASH radiotherapy based on ultra-high dose rate (UHDR) is actively being studied by the radiotherapy community. Dedicated UHDR electron devices are currently a mainstay for FLASH studies. PURPOSE To present the first Monte Carlo (MC) electron beam model for the UHDR capable Mobetron (FLASH-IQ) as a dose calculation and treatment planning platform for preclinical research and FLASH-radiotherapy (RT) clinical trials. METHODS The initial beamline geometry of the Mobetron was provided by the manufacturer, with the first-principal implementation realized in the Geant4-based GAMOS MC toolkit. The geometry and electron source characteristics, such as energy spectrum and beamline parameters, were tuned to match the central-axis percentage depth dose (PDD) and lateral profiles for the pristine beam measured during machine commissioning. The thickness of the small foil in secondary scatter affected the beam model dominantly and was fine tuned to achieve the best agreement with commissioning data. Validation of the MC beam modeling was performed by comparing the calculated PDDs and profiles with EBT-XD radiochromic film measurements for various combinations of applicators and inserts. RESULTS The nominal 9 MeV electron FLASH beams were best represented by a Gaussian energy spectrum with mean energy of 9.9 MeV and variance (σ) of 0.2 MeV. Good agreement between the MC beam model and commissioning data were demonstrated with maximal discrepancy < 3% for PDDs and profiles. Hundred percent gamma pass rate was achieved for all PDDs and profiles with the criteria of 2 mm/3%. With the criteria of 2 mm/2%, maximum, minimum and mean gamma pass rates were (100.0%, 93.8%, 98.7%) for PDDs and (100.0%, 96.7%, 99.4%) for profiles, respectively. CONCLUSIONS A validated MC beam model for the UHDR capable Mobetron is presented for the first time. The MC model can be utilized for direct dose calculation or to generate beam modeling input required for treatment planning systems for FLASH-RT planning. The beam model presented in this work should facilitate translational and clinical FLASH-RT for trials conducted on the Mobetron FLASH-IQ platform.
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Affiliation(s)
- Tianyuan Dai
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
- Department of Radiation Oncology Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, China
| | - Austin M Sloop
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | | | - Jacob P Sunnerberg
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Megan A Clark
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Ralph Young
- IntraOp Medical Corporation, Sunnyvale, California, USA
| | | | | | - Chris Patane
- IntraOp Medical Corporation, Sunnyvale, California, USA
| | - Michael Turk
- IntraOp Medical Corporation, Sunnyvale, California, USA
| | - Lesley Jarvis
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Brian W Pogue
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA
- Department of Medical Physics, Wisconsin Institutes for Medical Research, University of Wisconsin, Madison, Wisconsin, USA
| | - David J Gladstone
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Petr Bruza
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Rongxiao Zhang
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
- Department of Radiation Medicine, New York Medical College, Valhalla, New York, USA
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8
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Ashraf MR, Melemenidis S, Liu K, Grilj V, Jansen J, Velasquez B, Connell L, Schulz JB, Bailat C, Libed A, Manjappa R, Dutt S, Soto L, Lau B, Garza A, Larsen W, Skinner L, Yu AS, Surucu M, Graves EE, Maxim PG, Kry SF, Vozenin MC, Schüler E, Loo BW. Multi-Institutional Audit of FLASH and Conventional Dosimetry With a 3D Printed Anatomically Realistic Mouse Phantom. Int J Radiat Oncol Biol Phys 2024:S0360-3016(24)00433-4. [PMID: 38493902 DOI: 10.1016/j.ijrobp.2024.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 03/03/2024] [Accepted: 03/10/2024] [Indexed: 03/19/2024]
Abstract
PURPOSE We conducted a multi-institutional dosimetric audit between FLASH and conventional dose rate (CONV) electron irradiations by using an anatomically realistic 3-dimensional (3D) printed mouse phantom. METHODS AND MATERIALS A computed tomography (CT) scan of a live mouse was used to create a 3D model of bony anatomy, lungs, and soft tissue. A dual-nozzle 3D printer was used to print the mouse phantom using acrylonitrile butadiene styrene (∼1.02 g/cm3) and polylactic acid (∼1.24 g/cm3) simultaneously to simulate soft tissue and bone densities, respectively. The lungs were printed separately using lightweight polylactic acid (∼0.64 g/cm3). Hounsfield units (HU), densities, and print-to-print stability of the phantoms were assessed. Three institutions were each provided a phantom and each institution performed 2 replicates of irradiations at selected anatomic regions. The average dose difference between FLASH and CONV dose distributions and deviation from the prescribed dose were measured with radiochromic film. RESULTS Compared with the reference CT scan, CT scans of the phantom demonstrated mass density differences of 0.10 g/cm3 for bone, 0.12 g/cm3 for lung, and 0.03 g/cm3 for soft tissue regions. Differences in HU between phantoms were <10 HU for soft tissue and bone, with lung showing the most variation (54 HU), but with minimal effect on dose distribution (<0.5%). Mean differences between FLASH and CONV decreased from the first to the second replicate (4.3%-1.2%), and differences from the prescribed dose decreased for both CONV (3.6%-2.5%) and FLASH (6.4%-2.7%). Total dose accuracy suggests consistent pulse dose and pulse number, although these were not specifically assessed. Positioning variability was observed, likely due to the absence of robust positioning aids or image guidance. CONCLUSIONS This study marks the first dosimetric audit for FLASH using a nonhomogeneous phantom, challenging conventional calibration practices reliant on homogeneous phantoms. The comparison protocol offers a framework for credentialing multi-institutional studies in FLASH preclinical research to enhance reproducibility of biologic findings.
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Affiliation(s)
- M Ramish Ashraf
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Stavros Melemenidis
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Kevin Liu
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Veljko Grilj
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Switzerland
| | - Jeannette Jansen
- Radiation Oncology Laboratory, Department of Radiation Oncology, Lausanne, University Hospital and University of Lausanne, Switzerland
| | - Brett Velasquez
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Luke Connell
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Joseph B Schulz
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Claude Bailat
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Switzerland
| | - Aaron Libed
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Rakesh Manjappa
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Suparna Dutt
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Luis Soto
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Brianna Lau
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Aaron Garza
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - William Larsen
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Lawrie Skinner
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Amy S Yu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Murat Surucu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Edward E Graves
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California
| | - Peter G Maxim
- Department of Radiation Oncology, University of California, Irvine, California
| | - Stephen F Kry
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas; Imaging and Radiation Oncology Core, MD Anderson Cancer Center, Houston, USA
| | - Marie-Catherine Vozenin
- Radiation Oncology Laboratory, Department of Radiation Oncology, Lausanne, University Hospital and University of Lausanne, Switzerland; Radiotherapy and Radiobiology Sector, Radiation Therapy Service, University Hospital of Geneva, Geneva, Switzerland.
| | - Emil Schüler
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
| | - Billy W Loo
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California.
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9
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Kinj R, Gaide O, Jeanneret-Sozzi W, Dafni U, Viguet-Carrin S, Sagittario E, Kypriotou M, Chenal J, Duclos F, Hebeisen M, Falco T, Geyer R, Gonçalves Jorge P, Moeckli R, Bourhis J. Randomized phase II selection trial of FLASH and conventional radiotherapy for patients with localized cutaneous squamous cell carcinoma or basal cell carcinoma: A study protocol. Clin Transl Radiat Oncol 2024; 45:100743. [PMID: 38362466 PMCID: PMC10867306 DOI: 10.1016/j.ctro.2024.100743] [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: 05/08/2023] [Revised: 01/03/2024] [Accepted: 02/03/2024] [Indexed: 02/17/2024] Open
Abstract
Background Cutaneous basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most prevalent skin cancers in western countries. Surgery is the standard of care for these cancers and conventional external radiotherapy (CONV-RT) with conventional dose rate (0.03-0.06 Gy/sec) represents a good alternative when the patients or tumors are not amenable to surgery but routinely generates skin side effects. Low energy electron FLASH radiotherapy (FLASH-RT) is a new form of radiotherapy exploiting the biological advantage of the FLASH effect, which consists in delivering radiation dose in milliseconds instead of minutes in CONV-RT. In pre-clinical studies, when compared to CONV-RT, FLASH-RT induced a robust, reproducible and remarkable sparing of the normal healthy tissues, while the efficacy on tumors was preserved. In this context, we aim to prospectively evaluate FLASH-RT versus CONV-RT with regards to toxicity and oncological outcome in localized cutaneous BCC and SCC. Methods This is a randomized selection, non-comparative, phase II study of curative FLASH-RT versus CONV-RT in patients with T1-T2 N0 M0 cutaneous BCC and SCC. Patients will be randomly allocated to low energy electron FLASH-RT (dose rate: 220-270 Gy/s) or to CONV-RT arm. Small lesions (T1) will receive a single dose of 22 Gy and large lesions (T2) will receive 30 Gy in 5 fractions of 6 Gy over two weeks.The primary endpoint evaluates safety at 6 weeks after RT through grade ≥ 3 toxicity and efficacy through local control rate at 12 months. Approximately 60 patients in total will be randomized, considering on average 1-2 lesions and a maximum of 3 lesions per patients corresponding to the total of 96 lesions required. FLASH-RT will be performed using the Mobetron® (IntraOp, USA) with high dose rate functionality.LANCE (NCT05724875) is the first randomized trial evaluating FLASH-RT and CONV-RT in a curative setting.
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Affiliation(s)
- Rémy Kinj
- Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, CHUV, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland
| | - Olivier Gaide
- Service of Dermatology, CHUV, Lausanne University Hospital, Lausanne, Switzerland
| | - Wendy Jeanneret-Sozzi
- Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, CHUV, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland
| | - Urania Dafni
- Laboratory of Biostatistics School of Health Sciences University of Athens, Greece
| | - Stéphanie Viguet-Carrin
- Center of Experimental Therapeutics (CTE), Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Enea Sagittario
- Center of Experimental Therapeutics (CTE), Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Magdalini Kypriotou
- Center of Experimental Therapeutics (CTE), Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Julie Chenal
- Center of Experimental Therapeutics (CTE), Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Frederic Duclos
- Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, CHUV, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland
| | - Marine Hebeisen
- Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, CHUV, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland
| | - Teresa Falco
- Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, CHUV, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland
| | - Reiner Geyer
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Patrik Gonçalves Jorge
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Jean Bourhis
- Department of Radiation Oncology, Lausanne University Hospital and University of Lausanne, CHUV, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland
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10
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Liu K, Holmes S, Hooten B, Schüler E, Beddar S. Evaluation of ion chamber response for applications in electron FLASH radiotherapy. Med Phys 2024; 51:494-508. [PMID: 37696271 PMCID: PMC10840726 DOI: 10.1002/mp.16726] [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: 02/20/2023] [Revised: 08/08/2023] [Accepted: 08/23/2023] [Indexed: 09/13/2023] Open
Abstract
Ion chambers are required for calibration and reference dosimetry applications in radiation therapy (RT). However, exposure of ion chambers in ultra-high dose rate (UHDR) conditions pertinent to FLASH-RT leads to severe saturation and ion recombination, which limits their performance and usability. The purpose of this study was to comprehensively evaluate a set of commonly used commercially available ion chambers in RT, all with different design characteristics, and use this information to produce a prototype ion chamber with improved performance in UHDR conditions as a first step toward ion chambers specific for FLASH-RT. The Advanced Markus and Exradin A10, A26, and A20 ion chambers were evaluated. The chambers were placed in a water tank, at a depth of 2 cm, and exposed to an UHDR electron beam at different pulse repetition frequency (PRF), pulse width (PW), and pulse amplitude settings on an IntraOp Mobetron. Ion chamber responses were investigated for the various beam parameter settings to isolate their dependence on integrated dose, mean dose rate and instantaneous dose rate, dose-per-pulse (DPP), and their design features such as chamber type, bias voltage, and collection volume. Furthermore, a thin parallel-plate (TPP) prototype ion chamber with reduced collector plate separation and volume was constructed and equally evaluated as the other chambers. The charge collection efficiency of the investigated ion chambers decreased with increasing DPP, whereas the mean dose rate did not affect the response of the chambers (± 1%). The dependence of the chamber response on DPP was found to be solely related to the total dose within the pulse, and not on mean dose rate, PW, or instantaneous dose rate within the ranges investigated. The polarity correction factor (Ppol ) values of the TPP prototype, A10, and Advanced Markus chambers were found to be independent of DPP and dose rate (± 2%), while the A20 and A26 chambers yielded significantly larger variations and dependencies under the same conditions. Ion chamber performance evaluated under different irradiation conditions of an UHDR electron beam revealed a strong dependence on DPP and a negligible dependence on the mean and instantaneous dose rates. These results suggest that modifications to ion chambers design to improve their usability in UHDR beamlines should focus on minimizing DPP effects, with emphasis on optimizing the electric field strength, through the construction of smaller electrode separation and larger bias voltages. This was confirmed through the production and evaluation of a prototype ion chamber specifically designed with these characteristics.
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Affiliation(s)
- Kevin Liu
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | | | | | - Emil Schüler
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Sam Beddar
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
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11
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Klett KC, Martin-Villa BC, Villarreal VS, Melemenidis S, Viswanathan V, Manjappa R, Ashraf MR, Soto L, Lau B, Dutt S, Rankin EB, Loo BW, Heilshorn SC. Human enteroids as a tool to study conventional and ultra-high dose rate radiation. Integr Biol (Camb) 2023; 15:zyad013. [PMID: 37874173 PMCID: PMC10594601 DOI: 10.1093/intbio/zyad013] [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: 07/16/2023] [Revised: 09/22/2023] [Accepted: 09/26/2023] [Indexed: 10/25/2023]
Abstract
Radiation therapy, one of the most effective therapies to treat cancer, is highly toxic to healthy tissue. The delivery of radiation at ultra-high dose rates, FLASH radiation therapy (FLASH), has been shown to maintain therapeutic anti-tumor efficacy while sparing normal tissues compared to conventional dose rate irradiation (CONV). Though promising, these studies have been limited mainly to murine models. Here, we leveraged enteroids, three-dimensional cell clusters that mimic the intestine, to study human-specific tissue response to radiation. We observed enteroids have a greater colony growth potential following FLASH compared with CONV. In addition, the enteroids that reformed following FLASH more frequently exhibited proper intestinal polarity. While we did not observe differences in enteroid damage across groups, we did see distinct transcriptomic changes. Specifically, the FLASH enteroids upregulated the expression of genes associated with the WNT-family, cell-cell adhesion, and hypoxia response. These studies validate human enteroids as a model to investigate FLASH and provide further evidence supporting clinical study of this therapy. Insight Box Promising work has been done to demonstrate the potential of ultra-high dose rate radiation (FLASH) to ablate cancerous tissue, while preserving healthy tissue. While encouraging, these findings have been primarily observed using pre-clinical murine and traditional two-dimensional cell culture. This study validates the use of human enteroids as a tool to investigate human-specific tissue response to FLASH. Specifically, the work described demonstrates the ability of enteroids to recapitulate previous in vivo findings, while also providing a lens through which to probe cellular and molecular-level responses to FLASH. The human enteroids described herein offer a powerful model that can be used to probe the underlying mechanisms of FLASH in future studies.
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Affiliation(s)
- Katarina C Klett
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Victoria S Villarreal
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Stavros Melemenidis
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Vignesh Viswanathan
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Rakesh Manjappa
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - M Ramish Ashraf
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Luis Soto
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Brianna Lau
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Suparna Dutt
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Erinn B Rankin
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA, USA
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Billy W Loo
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Sarah C Heilshorn
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
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