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Tobias Böhlen T, Psoroulas S, Aylward JD, Beddar S, Douralis A, Delpon G, Garibaldi C, Gasparini A, Schüler E, Stephan F, Moeckli R, Subiel A. Recording and reporting of ultra-high dose rate "FLASH" delivery for preclinical and clinical settings. Radiother Oncol 2024; 200:110507. [PMID: 39245070 DOI: 10.1016/j.radonc.2024.110507] [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: 01/26/2024] [Revised: 08/08/2024] [Accepted: 08/19/2024] [Indexed: 09/10/2024]
Abstract
Treatments at ultra-high dose rate (UHDR) have the potential to improve the therapeutic index of radiation therapy (RT) by sparing normal tissues compared to conventional dose rate irradiations. Insufficient and inconsistent reporting in physics and dosimetry of preclinical and translational studies may have contributed to a reproducibility crisis of radiobiological data in the field. Consequently, the development of a common terminology, as well as common recording, reporting, dosimetry, and metrology standards is required. In the context of UHDR irradiations, the temporal dose delivery parameters are of importance, and under-reporting of these parameters is also a concern.This work proposes a standardization of terminology, recording, and reporting to enhance comparability of both preclinical and clinical UHDR studies and and to allow retrospective analyses to aid the understanding of the conditions which give rise to the FLASH effect.
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Affiliation(s)
- Till Tobias Böhlen
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Serena Psoroulas
- Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI, Switzerland; Klinik für Radio-Onkologie, UniversitätsSpital Zürich, Switzerland
| | - Jack D Aylward
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK; Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK; Medical Physics, School of Applied Sciences, University of the West of England, Bristol, UK
| | - Sam Beddar
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Grégory Delpon
- Institut de Cancérologie de l'Ouest, Medical Physics Department, Saint-Herblain, France; Nantes Université, IMT Atlantique, CNRS/IN2P3, SUBATECH, Nantes, France
| | - Cristina Garibaldi
- IEO, Unit of Radiation Research, European Institute of Oncology IRCCS, 20141 Milan, Italy
| | - Alessia Gasparini
- CORE, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Medical Physics Department, Iridium Netwerk, Wilrijk, Belgium
| | - Emil Schüler
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Frank Stephan
- Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, 15738 Zeuthen, Germany
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland.
| | - Anna Subiel
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK; University College London, Gower Street, London WC1E 6BT, UK.
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Tobias Böhlen T, Zeverino M, Germond JF, Kinj R, Schiappacasse L, Bochud F, Herrera F, Bourhis J, Moeckli R. Hybrid ultra-high and conventional dose rate treatments with electrons and photons for the clinical transfer of FLASH-RT to deep-seated targets: A treatment planning study. Radiother Oncol 2024:110576. [PMID: 39395673 DOI: 10.1016/j.radonc.2024.110576] [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: 06/18/2024] [Revised: 09/17/2024] [Accepted: 10/06/2024] [Indexed: 10/14/2024]
Abstract
PURPOSE This study explores the dosimetric feasibility and plan quality of hybrid ultra-high dose rate (UHDR) electron and conventional dose rate (CDR) photon radiotherapy (HUC RT) for treating deep-seated tumours with FLASH-RT. METHODS HUC treatment planning was conducted optimizing a broad UHDR electron beam (between 20-250 MeV) combined with a CDR VMAT for a glioblastoma, a pancreatic cancer, and a prostate cancer case. HUC plans were based on clinical prescription and fractionation schemes and compared against clinically delivered plans. Considering a HUC boost treatment for the glioblastoma consisting of a 15-Gy-single-fraction UHDR electron boost supplemented with VMAT, two scenarios for FLASH sparing were assessed using FLASH-modifying-factor-weighted doses. RESULTS For all three patient cases, HUC treatment plans demonstrated comparable dosimetric quality to clinical plans, with similar PTV coverage (V95% within 0.5 %), homogeneity, and critical OAR-sparing. At the same time, HUC plans delivered a substantial portion of the dose to the PTV (Dmedian of 50-69 %) and surrounding tissues at UHDR. For the HUC boost treatment of the glioblastoma, the first FLASH sparing scenario showed a moderate FLASH sparing magnitude (10 % for D2%,PTV) for the 15-Gy UHDR electron boost, while the second scenario indicated a more substantial sparing of brain tissues inside and outside the PTV (32 % for D2%,PTV, 31 % for D2%,Brain). CONCLUSIONS From a planning perspective, HUC treatments represent a feasible approach for delivering dosimetrically conformal UHDR treatments, potentially mitigating technical challenges associated with delivering conformal FLASH-RT for deep-seated tumours. While further research is needed to optimize HUC fractionation and delivery schemes for specific patient cohorts, HUC treatments offer a promising avenue for the clinical transfer of FLASH-RT.
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Affiliation(s)
- Till Tobias Böhlen
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Michele Zeverino
- 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
| | - Rémy Kinj
- Department of Radiation Oncology, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Luis Schiappacasse
- 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
| | - Fernanda Herrera
- 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
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland.
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Cheng C, Xu L, Jing H, Selvaraj B, Lin H, Pennock M, Chhabra AM, Hasan S, Zhai H, Zhang Y, Nie K, Bakst RL, Kabarriti R, Choi JI, Lee NY, Simone CB, Kang M, Wu H. The Potential and Challenges of Proton FLASH in Head and Neck Cancer Reirradiation. Cancers (Basel) 2024; 16:3249. [PMID: 39409872 PMCID: PMC11482542 DOI: 10.3390/cancers16193249] [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: 07/11/2024] [Revised: 09/17/2024] [Accepted: 09/19/2024] [Indexed: 10/19/2024] Open
Abstract
Ultrahigh-dose-rate therapy, also known as FLASH radiotherapy (RT), is an emerging technique that is garnering significant interest in cancer treatment due to its potential to revolutionize therapy. This method can achieve comparable tumor control to conventional-dose-rate RT while offering the enhanced protection of normal tissue through the FLASH-sparing effect. This innovative technique has demonstrated promising results in preclinical studies involving animals and cell lines. Particularly noteworthy is its potential application in treating head and neck (HN) cancers, especially in patients with challenging recurrent tumors and reirradiation cases, where the toxicity rates with conventional radiotherapy are high. Such applications aim to enhance tumor control while minimizing side effects and preserving patients' quality of life. In comparison to electron or photon FLASH modalities, proton therapy has demonstrated superior dosimetric and delivery characteristics and is a safe and effective FLASH treatment for human malignancies. Compared to the transmission proton FLASH, single-energy Bragg peak FLASH is a novel delivery method that allows highly conformal doses to targets and minimal radiation doses to crucial OARs. Proton Bragg peak FLASH for HN cancer has still not been well studied. This review highlights the significance of proton FLASH in enhancing cancer therapy by examining the advantages and challenges of using it for HN cancer reirradiation.
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Affiliation(s)
- Chingyun Cheng
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901, USA; (C.C.)
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA
| | - Liming Xu
- Department of Radiation Oncology, Tianjin Medical University Cancer Institute & Hospital, National Clinical Research Center for Cancer, Tianjin’s Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, China
| | - Hao Jing
- Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
| | | | - Haibo Lin
- New York Proton Center, New York, NY 10035, USA
| | - Michael Pennock
- Department of Radiation Oncology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY 10461, USA
| | | | | | | | - Yin Zhang
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901, USA; (C.C.)
| | - Ke Nie
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901, USA; (C.C.)
| | - Richard L. Bakst
- Department of Radiation Oncology–Radiation Oncology Associates, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Rafi Kabarriti
- Department of Radiation Oncology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY 10461, USA
| | - J. Isabelle Choi
- New York Proton Center, New York, NY 10035, USA
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Nancy Y. Lee
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Charles B. Simone
- New York Proton Center, New York, NY 10035, USA
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Minglei Kang
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901, USA; (C.C.)
- New York Proton Center, New York, NY 10035, USA
| | - Hui Wu
- Department of Radiation Oncology, The Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital, Zhengzhou 450008, China
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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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Clark M, Harms J, Vasyltsiv R, Sloop A, Kozelka J, Simon B, Zhang R, Gladstone D, Bruza P. Quantitative, real-time scintillation imaging for experimental comparison of different dose and dose rate estimations in UHDR proton pencil beams. Med Phys 2024; 51:6402-6411. [PMID: 38860497 DOI: 10.1002/mp.17247] [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: 10/17/2023] [Revised: 03/28/2024] [Accepted: 04/02/2024] [Indexed: 06/12/2024] Open
Abstract
BACKGROUND Ultra-high dose rate radiotherapy (UHDR-RT) has demonstrated normal tissue sparing capabilities, termed the FLASH effect; however, available dosimetry tools make it challenging to characterize the UHDR beams with sufficiently high concurrent spatial and temporal resolution. Novel dosimeters are needed for safe clinical implementation and improved understanding of the effect of UHDR-RT. PURPOSE Ultra-fast scintillation imaging has been shown to provide a unique tool for spatio-temporal dosimetry of conventional cyclotron pencil beam scanning (PBS) deliveries, indicating the potential use for characterization of UHDR PBS proton beams. The goal of this work is to introduce this novel concept and demonstrate its capabilities in recording high-resolution dose rate maps at FLASH-capable proton beam currents, as compared to log-based dose rate calculation, internally developed UHDR beam simulation, and a fast point detector (EDGE diode). METHODS The light response of a scintillator sheet located at isocenter and irradiated by PBS proton fields (40-210 nA, 250 MeV) was imaged by an ultra-fast iCMOS camera at 4.5-12 kHz sampling frequency. Camera sensor and image intensifier gain were optimized to maximize the dynamic range; the camera acquisition rate was also varied to evaluate the optimal sampling frequency. Large field delivery enabled flat field acquisition for evaluation of system response homogeneity. Image intensity was calibrated to dose with film and the recorded spatio-temporal data was compared to a PPC05 ion chamber, log-based reconstruction, and EDGE diode. Dose and dose rate linearity studies were performed to evaluate agreement under various beam conditions. Calculation of full-field mean and PBS dose rate maps were calculated to highlight the importance of high resolution, full-field information in UHDR studies. RESULTS Camera response was linear with dose (R2 = 0.997) and current (R22 = 0.98) in the range from 2-22 Gy and 40-210 nA, respectively, when compared to ion chamber readings. The deviation of total irradiation time calculated with the imaging system from the log file recordings decreased from 0.07% to 0.03% when imaging at 12 kfps versus 4.5 kfps. Planned and delivered spot positions agreed within 0.2 ± $\pm$ 0.1 mm and total irradiation time agreed within 0.2 ± $\pm$ 0.2 ms when compared with the log files, indicating the high concurrent spatial and temporal resolution. For all deliveries, the PBS dose rate measured at the diode location agreed between the imaging and the diode within 3% ± $\pm$ 2% and with the simulation within 5% ± $\pm$ 3% CONCLUSIONS: Full-field mapping of dose and dose rate is imperative for complete understanding of UHDR PBS proton dose delivery. The high linearity and various spatiotemporal metric reporting capabilities confirm the continued use of this camera system for UHDR beam characterization, especially for spatially resolved dose rate information.
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Affiliation(s)
- Megan Clark
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Joseph Harms
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Roman Vasyltsiv
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Austin Sloop
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | | | - Bill Simon
- Sun Nuclear Inc., Melbourne, Florida, USA
| | - Rongxiao Zhang
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - David Gladstone
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Petr Bruza
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
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Held KD, McNamara AL, Daartz J, Bhagwat MS, Rothwell B, Schuemann J. Dose Rate Effects from the 1950s through to the Era of FLASH. Radiat Res 2024; 202:161-176. [PMID: 38954556 PMCID: PMC11426361 DOI: 10.1667/rade-24-00024.1] [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: 01/19/2024] [Accepted: 05/09/2024] [Indexed: 07/04/2024]
Abstract
Numerous dose rate effects have been described over the past 6-7 decades in the radiation biology and radiation oncology literature depending on the dose rate range being discussed. This review focuses on the impact and understanding of altering dose rates in the context of radiation therapy, but does not discuss dose rate effects as relevant to radiation protection. The review starts with a short historic review of early studies on dose rate effects, considers mechanisms thought to underlie dose rate dependencies, then discusses some current issues in clinical findings with altered dose rates, the importance of dose rate in brachytherapy, and the current timely topic of the use of very high dose rates, so-called FLASH radiotherapy. The discussion includes dose rate effects in vitro in cultured cells, in in vivo experimental systems and in the clinic, including both tumors and normal tissues. Gaps in understanding dose rate effects are identified, as are opportunities for improving clinical use of dose rate modulation.
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Affiliation(s)
- Kathryn D Held
- Department of Radiation Oncology, Massachusetts General Hospital Hospital/Harvard Medical School, Boston, Massachusetts 02114
- National Council on Radiation Protection and Measurements, Bethesda, Maryland 20814
| | - Aimee L McNamara
- Department of Radiation Oncology, Massachusetts General Hospital Hospital/Harvard Medical School, Boston, Massachusetts 02114
| | - Juliane Daartz
- Department of Radiation Oncology, Massachusetts General Hospital Hospital/Harvard Medical School, Boston, Massachusetts 02114
| | - Mandar S Bhagwat
- Department of Radiation Oncology, Massachusetts General Hospital Hospital/Harvard Medical School, Boston, Massachusetts 02114
| | - Bethany Rothwell
- Department of Radiation Oncology, Massachusetts General Hospital Hospital/Harvard Medical School, Boston, Massachusetts 02114
| | - Jan Schuemann
- Department of Radiation Oncology, Massachusetts General Hospital Hospital/Harvard Medical School, Boston, Massachusetts 02114
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Oh K, Hyun MA, Gallagher KJ, Yan Y, Zhou S. Characterization of a commercial plastic scintillator for electron FLASH dosimetry. J Appl Clin Med Phys 2024; 25:e14451. [PMID: 38952057 PMCID: PMC11302813 DOI: 10.1002/acm2.14451] [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: 01/29/2024] [Revised: 06/12/2024] [Accepted: 06/15/2024] [Indexed: 07/03/2024] Open
Abstract
PURPOSE This study investigated the potential of a commercially available plastic scintillator, the Exradin W2, as a real-time dosimeter for ultra-high-dose-rate (UHDR) electron beams. This work aimed to characterize this system's performance under UHDR conditions and addressed limitations inherent to other conventional dosimetry systems. METHODS AND MATERIALS We assessed the W2's performance as a UHDR electron dosimeter using a 16 MeV UHDR electron beam from the FLASH research extension (FLEX) system. Additionally, the vendor provided a beta firmware upgrade to better handle the processing of the high signal generated in the UHDR environment. We evaluated the W2 regarding dose-per-pulse, pulse repetition rate, charge versus distance, and pulse linearity. Absorbed dose measurements were compared against those from a plane-parallel ionization chamber, optically stimulated luminescent dosimeters and radiochromic film. RESULTS We observed that the 1 × 1 mm W2 scintillator with the MAX SD was more suitable for UHDR dosimetry compared to the 1 × 3 mm W2 scintillator, capable of matching film measurements within 2% accuracy for dose-per-pulse up to 3.6 Gy/pulse. The W2 accurately ascertained the inverse square relationship regarding charge versus virtual source distance with R2 of ∼1.00 for all channels. Pulse linearity was accurately measured with the W2, demonstrating a proportional response to the delivered pulse number. There was no discernible impact on the measured charge of the W2 when switching between the available repetition rates of the FLEX system (18-180 pulses/s), solidifying consistent beam output across pulse frequencies. CONCLUSIONS This study tested a commercial plastic scintillator detector in a UHDR electron beam, paving the way for its potential use as a real-time, patient-specific dosimetry tool for future FLASH radiotherapy treatments. Further research is warranted to test and improve the signal processing of the W2 dosimetry system to accurately measure in UHDR environments using exceedingly high dose-per-pulse and pulse numbers.
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Affiliation(s)
- Kyuhak Oh
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | - Megan A. Hyun
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | | | - Ying Yan
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | - Sumin Zhou
- University of Nebraska Medical CenterOmahaNebraskaUSA
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Harrison N, Kang M, Liu R, Charyyev S, Wahl N, Liu W, Zhou J, Higgins KA, Simone CB, Bradley JD, Dynan WS, Lin L. A Novel Inverse Algorithm To Solve the Integrated Optimization of Dose, Dose Rate, and Linear Energy Transfer of Proton FLASH Therapy With Sparse Filters. Int J Radiat Oncol Biol Phys 2024; 119:957-967. [PMID: 38104869 DOI: 10.1016/j.ijrobp.2023.11.061] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 09/27/2023] [Accepted: 11/25/2023] [Indexed: 12/19/2023]
Abstract
PURPOSE The recently proposed Integrated Physical Optimization Intensity Modulated Proton Therapy (IPO-IMPT) framework allows simultaneous optimization of dose, dose rate, and linear energy transfer (LET) for ultra-high dose rate (FLASH) treatment planning. Finding solutions to IPO-IMPT is difficult because of computational intensiveness. Nevertheless, an inverse solution that simultaneously specifies the geometry of a sparse filter and weights of a proton intensity map is desirable for both clinical and preclinical applications. Such solutions can reduce effective biologic dose to organs at risk in patients with cancer as well as reduce the number of animal irradiations needed to derive extra biologic dose models in preclinical studies. METHODS AND MATERIALS Unlike the initial forward heuristic, this inverse IPO-IMPT solution includes simultaneous optimization of sparse range compensation, sparse range modulation, and spot intensity. The daunting computational tasks vital to this endeavor were resolved iteratively with a distributed computing framework to enable Simultaneous Intensity and Energy Modulation and Compensation (SIEMAC). SIEMAC was demonstrated on a human patient with central lung cancer and a minipig. RESULTS SIEMAC simultaneously improves maps of spot intensities and patient-field-specific sparse range compensators and range modulators. For the patient with lung cancer, at our maximum nozzle current of 300 nA, dose rate coverage above 100 Gy/s increased from 57% to 96% in the lung and from 93% to 100% in the heart, and LET coverage above 4 keV/µm dropped from 68% to 9% in the lung and from 26% to <1% in the heart. For a simple minipig plan, the full-width half-maximum of the dose, dose rate, and LET distributions decreased by 30%, 1.6%, and 57%, respectively, again with similar target dose coverage, thus reducing uncertainty in these quantities for preclinical studies. CONCLUSIONS The inverse solution to IPO-IMPT demonstrated the capability to simultaneously modulate subspot proton energy and intensity distributions for clinical and preclinical studies.
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Affiliation(s)
| | | | - Ruirui Liu
- Emory University, Atlanta, Georgia; University of Nebraska, Omaha, Nebraska
| | | | - Niklas Wahl
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Wei Liu
- Mayo Clinic, Phoenix, Arizona
| | - Jun Zhou
- Emory University, Atlanta, Georgia
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Zhao X, Huang S, Lin H, Choi JI, Zhu K, Simone CB, Yan X, Kang M. A Novel Dose Rate Optimization Method to Maximize Ultrahigh-Dose-Rate Coverage of Critical Organs at Risk Without Compromising Dosimetry Metrics in Proton Pencil Beam Scanning FLASH Radiation Therapy. Int J Radiat Oncol Biol Phys 2024:S0360-3016(24)00735-1. [PMID: 38879087 DOI: 10.1016/j.ijrobp.2024.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/12/2024] [Accepted: 06/09/2024] [Indexed: 07/10/2024]
Abstract
PURPOSE This study aimed to investigate a dose rate optimization framework based on the spot-scanning patterns to improve ultrahigh-dose-rate coverage of critical organs at risk (OARs) for proton pencil beam scanning (PBS) FLASH radiation therapy (ultrahigh dose-rate (often referred to as >40 Gy per second) delivery) and present implementation of a genetic algorithm (GA) method for spot sequence optimization to achieve PBS FLASH dose rate optimization under relatively low nozzle beam currents. METHODS AND MATERIALS First, a multifield FLASH plan was developed to meet all the dosimetric goals and optimal FLASH dose rate coverage by considering the deliverable minimum monitor unit constraint. Then, a GA method was implemented into the in-house treatment platform to maximize the dose rate by exploring the best spot delivery sequence. A phantom study was performed to evaluate the effectiveness of the dose rate optimization. Then, 10 consecutive plans for patients with lung cancer previously treated using PBS intensity-modulated proton therapy were optimized using 45 GyRBE in 3 fractions for both transmission and Bragg peak FLASH radiation therapy for further validation. The spot delivery sequence of each treatment field was optimized using this GA. The ultrahigh-dose-rate-volume histogram and dose rate coverage V40GyRBE/s were investigated to assess the efficacy of dose rate optimization quantitatively. RESULTS Using a relatively low monitor unit/spot of 150, corresponding to a nozzle beam current of 65 nA, the FLASH dose rate ratio V40GyRBE/s of the OAR contour of the core was increased from 0% to ∼60% in the phantom study. In the patients with lung cancer, the ultrahigh-dose-rate coverage V40GyRBE/s was improved from 15.2%, 15.5%, 17.6%, and 16.0% before the delivery sequence optimization to 31.8%, 43.5%, 47.6%, and 30.5% after delivery sequence optimization in the lungs-GTV (gross tumor volume), spinal cord, esophagus, and heart (for all, P < .001). When the beam current increased to 130 nA, V40GyRBE/s was improved from 45.1%, 47.1%, 51.2%, and 51.4% to 65.3%, 83.5%, 88.1%, and 69.4% (P < .05). The averaged V40GyRBE/s for the target and OARs increased from 12.9% to 41.6% and 46.3% to 77.5% for 65 and 130 nA, respectively, showing significant improvements based on a clinical proton system. After optimizing the dose rate for the Bragg peak FLASH technique with a beam current of 340 nA, the V40GyRBE/s values for the lung GTV, spinal cord, esophagus, and heart were increased by 8.9%, 15.8%, 22%, and 20.8%, respectively. CONCLUSIONS An optimal plan quality can be maintained as the spot delivery sequence optimization is a separate independent process after the plan optimization. Both the phantom and patient results demonstrated that novel spot delivery sequence optimization can effectively improve the ultrahigh-dose-rate coverage for critical OARs, which can potentially be applied in clinical practice for better OARs-sparing efficacy.
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Affiliation(s)
- Xingyi Zhao
- State Key Laboratory of Nuclear Physics and Technology, and Key Laboratory of HEDP of the Ministry of Education, Center for Applied Physics and Technology, Peking University, Beijing, China; New York Proton Center, New York, New York
| | - Sheng Huang
- Radiation Oncology, Tianjin Medical University Cancer Institute & Hospital, National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Haibo Lin
- New York Proton Center, New York, New York; Departments of Radiation Oncology and Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - J Isabelle Choi
- New York Proton Center, New York, New York; Departments of Radiation Oncology and Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Kun Zhu
- State Key Laboratory of Nuclear Physics and Technology, and Key Laboratory of HEDP of the Ministry of Education, Center for Applied Physics and Technology, Peking University, Beijing, China
| | - Charles B Simone
- New York Proton Center, New York, New York; Departments of Radiation Oncology and Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Xueqing Yan
- State Key Laboratory of Nuclear Physics and Technology, and Key Laboratory of HEDP of the Ministry of Education, Center for Applied Physics and Technology, Peking University, Beijing, China.
| | - Minglei Kang
- New York Proton Center, New York, New York; Departments of Radiation Oncology and Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York.
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Oh K, Gallagher KJ, Yan Y, Zhou S. Commissioning and initial validation of Eclipse eMC algorithm for the electron FLASH research extension (FLEX) system for pre-clinical studies. J Appl Clin Med Phys 2024; 25:e14289. [PMID: 38319666 PMCID: PMC11087161 DOI: 10.1002/acm2.14289] [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: 09/04/2023] [Revised: 12/13/2023] [Accepted: 01/22/2024] [Indexed: 02/07/2024] Open
Abstract
PURPOSE To investigate the feasibility of commissioning the 16 MeV electron FLASH Extension (FLEX) in the commercial treatment planning system (TPS) for biomedical research with cell and mouse models, and in silico treatment planning studies. METHODS To commission the FLEX system with the electron Monte Carlo (eMC) algorithm in the commercial TPS, radiochromic film was used to measure the vendor-recommended beam data. Once the beam model was generated for the eMC algorithm, supplemental measurements were collected for validation purposes and compared against the TPS-calculated results. Additionally, the newly commissioned 16 MeV FLASH beam was compared to the corresponding 16 MeV conventional electron beam. RESULTS The eMC algorithm effectively modeled the FLEX system. The eMC-calculated PDDs and profiles for the 16 MeV electron FLASH beam agreed with measured values within 1%, on average, for 6 × 6 cm2 and 10 × 10 cm2 applicators. Flatness and symmetry deviated by less than 1%, while FWHM and penumbra agreed within 1 mm for both eMC-calculated and measured profiles. Additionally, the small field (i.e., 2-cm diameter cutout) that was measured for validation purposes agreed with TPS-calculated results within 1%, on average, for both the PDD and profiles. The FLASH and conventional dose rate 16 MeV electron beam were in agreement in regard to energy, but the profiles for larger field sizes began to deviate (>10 × 10 cm2) due to the forward-peaked nature of the FLASH beam. For cell irradiation experiments, the measured and eMC-calculated in-plane and cross-plane absolute dose profiles agreed within 1%, on average. CONCLUSIONS The FLEX system was successfully commissioned in the commercial TPS using the eMC algorithm, which accurately modeled the forward-peaked nature of the FLASH beam. A commissioned TPS for FLASH will be useful for pre-clinical cell and animal studies, as well as in silico FLASH treatment planning studies for future clinical implementation.
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Affiliation(s)
- Kyuhak Oh
- Department of Radiation OncologyUniversity of Nebraska Medical CenterOmahaNebraskaUSA
| | - Kyle J. Gallagher
- Department of Radiation OncologyUniversity of Nebraska Medical CenterOmahaNebraskaUSA
| | - Ying Yan
- Department of Radiation OncologyUniversity of Nebraska Medical CenterOmahaNebraskaUSA
| | - Sumin Zhou
- Department of Radiation OncologyUniversity of Nebraska Medical CenterOmahaNebraskaUSA
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11
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Cengel KA, Kim MM, Diffenderfer ES, Busch TM. FLASH Radiotherapy: What Can FLASH's Ultra High Dose Rate Offer to the Treatment of Patients With Sarcoma? Semin Radiat Oncol 2024; 34:218-228. [PMID: 38508786 DOI: 10.1016/j.semradonc.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
FLASH is an emerging treatment paradigm in radiotherapy (RT) that utilizes ultra-high dose rates (UHDR; >40 Gy)/s) of radiation delivery. Developing advances in technology support the delivery of UHDR using electron and proton systems, as well as some ion beam units (eg, carbon ions), while methods to achieve UHDR with photons are under investigation. The major advantage of FLASH RT is its ability to increase the therapeutic index for RT by shifting the dose response curve for normal tissue toxicity to higher doses. Numerous preclinical studies have been conducted to date on FLASH RT for murine sarcomas, alongside the investigation of its effects on relevant normal tissues of skin, muscle, and bone. The tumor control achieved by FLASH RT of sarcoma models is indistinguishable from that attained by treatment with standard RT to the same total dose. FLASH's high dose rates are able to mitigate the severity or incidence of RT side effects on normal tissues as evaluated by endpoints ranging from functional sparing to histological damage. Large animal studies and clinical trials of canine patients show evidence of skin sparing by FLASH vs. standard RT, but also caution against delivery of high single doses with FLASH that exceed those safely applied with standard RT. Also, a human clinical trial has shown that FLASH RT can be delivered safely to bone metastasis. Thus, data to date support continued investigations of clinical translation of FLASH RT for the treatment of patients with sarcoma. Toward this purpose, hypofractionated irradiation schemes are being investigated for FLASH effects on sarcoma and relevant normal tissues.
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Affiliation(s)
- Keith A Cengel
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania..
| | - Michele M Kim
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Eric S Diffenderfer
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Theresa M Busch
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Rank L, Dogan O, Kopp B, Mein S, Verona-Rinati G, Kranzer R, Marinelli M, Mairani A, Tessonnier T. Development and benchmarking of a dose rate engine for raster-scanned FLASH helium ions. Med Phys 2024; 51:2251-2262. [PMID: 37847027 PMCID: PMC10939952 DOI: 10.1002/mp.16793] [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: 12/19/2022] [Revised: 09/14/2023] [Accepted: 10/06/2023] [Indexed: 10/18/2023] Open
Abstract
BACKGROUND Radiotherapy with charged particles at high dose and ultra-high dose rate (uHDR) is a promising technique to further increase the therapeutic index of patient treatments. Dose rate is a key quantity to predict the so-called FLASH effect at uHDR settings. However, recent works introduced varying calculation models to report dose rate, which is susceptible to the delivery method, scanning path (in active beam delivery) and beam intensity. PURPOSE This work introduces an analytical dose rate calculation engine for raster scanned charged particle beams that is able to predict dose rate from the irradiation plan and recorded beam intensity. The importance of standardized dose rate calculation methods is explored here. METHODS Dose is obtained with an analytical pencil beam algorithm, using pre-calculated databases for integrated depth dose distributions and lateral penumbra. Dose rate is then calculated by combining dose information with the respective particle fluence (i.e., time information) using three dose-rate-calculation models (mean, instantaneous, and threshold-based). Dose rate predictions for all three models are compared to uHDR helium ion beam (145.7 MeV/u, range in water of approximatively 14.6 cm) measurements performed at the Heidelberg Ion Beam Therapy Center (HIT) with a diamond-detector prototype. Three scanning patterns (scanned or snake-like) and four field sizes are used to investigate the dose rate differences. RESULTS Dose rate measurements were in good agreement with in-silico generated distributions using the here introduced engine. Relative differences in dose rate were below 10% for varying depths in water, from 2.3 to 14.8 cm, as well as laterally in a near Bragg peak area. In the entrance channel of the helium ion beam, dose rates were predicted within 7% on average for varying irradiated field sizes and scanning patterns. Large differences in absolute dose rate values were observed for varying calculation methods. For raster-scanned irradiations, the deviation between mean and threshold-based dose rate at the investigated point was found to increase with the field size up to 63% for a 10 mm × 10 mm field, while no significant differences were observed for snake-like scanning paths. CONCLUSIONS This work introduces the first dose rate calculation engine benchmarked to instantaneous dose rate, enabling dose rate predictions for physical and biophysical experiments. Dose rate is greatly affected by varying particle fluence, scanning path, and calculation method, highlighting the need for a consensus among the FLASH community on how to calculate and report dose rate in the future. The here introduced engine could help provide the necessary details for the analysis of the sparing effect and uHDR conditions.
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Affiliation(s)
- Luisa Rank
- Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
- Karlsruhe Institute of Technology (KIT), Faculty of Physics, Karlsruhe, Germany
| | - Ozan Dogan
- Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
- Heidelberg University, Faculty of Physics and Astronomy, Heidelberg, Germany
| | - Benedikt Kopp
- Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
| | - Stewart Mein
- Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
- Clinical Cooperation Unit Translational Radiation Oncology, German Cancer Consortium (DKTK) Core-Center Heidelberg, National Center for Tumor Diseases (NCT), Heidelberg University Hospital (UKHD) and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Division of Molecular and Translational Radiation Oncology, Heidelberg Faculty of Medicine (MFHD) and Department of Radiation Oncology, Heidelberg University Hospital (UKHD), Heidelberg, Germany
- Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg University Hospital (UKHD), Heidelberg Faculty of Medicine (MFHD) and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | - Rafael Kranzer
- PTW-Freiburg, Freiburg, Germany
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University Oldenburg, Germany
| | - Marco Marinelli
- Industrial Engineering Department, University of Rome “Tor Vergata”, Rome, Italy
| | - Andrea Mairani
- Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
- Clinical Cooperation Unit Translational Radiation Oncology, German Cancer Consortium (DKTK) Core-Center Heidelberg, National Center for Tumor Diseases (NCT), Heidelberg University Hospital (UKHD) and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Division of Molecular and Translational Radiation Oncology, Heidelberg Faculty of Medicine (MFHD) and Department of Radiation Oncology, Heidelberg University Hospital (UKHD), Heidelberg, Germany
- Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg University Hospital (UKHD), Heidelberg Faculty of Medicine (MFHD) and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Medical Physics, National Centre of Oncological Hadrontherapy (CNAO), Pavia, Italy
| | - Thomas Tessonnier
- Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
- Clinical Cooperation Unit Translational Radiation Oncology, German Cancer Consortium (DKTK) Core-Center Heidelberg, National Center for Tumor Diseases (NCT), Heidelberg University Hospital (UKHD) and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg University Hospital (UKHD), Heidelberg Faculty of Medicine (MFHD) and German Cancer Research Center (DKFZ), Heidelberg, Germany
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Galts A, Hammi A. FLASH radiotherapy sparing effect on the circulating lymphocytes in pencil beam scanning proton therapy: impact of hypofractionation and dose rate. Phys Med Biol 2024; 69:025006. [PMID: 38081067 DOI: 10.1088/1361-6560/ad144e] [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: 09/22/2023] [Accepted: 12/11/2023] [Indexed: 01/06/2024]
Abstract
Purpose. The sparing effect of ultra-high dose rate (FLASH) radiotherapy has been reported, but its potential to mitigate depletion of circulating blood and lymphocytes (CL) has not been investigated in pencil-beam scanning-based (PBS) proton therapy, which could potentially reduce the risk of radiation-induced lymphopenia.Material and methods. A time-dependent framework was used to score the dose to the CL during the course of radiotherapy. For brain patients, cerebral vasculatures were semi-automatic segmented from 3T MR-angiography data. A dynamic beam delivery system was developed capable of simulating spatially varying instantaneous dose rates of PBS treatment plans, and which is based on realistic beam delivery parameters that are available clinically. We simulated single and different hypofractionated PBS intensity modulated proton therapy (IMPT) FLASH schemes using 600 nA beam current along with conventionally fractionated IMPT treatment plan at 2 nA beam current. The dosimetric impact of treatment schemes on CL was quantified, and we also evaluated the depletion in subsets of CL based on their radiosensitivity.Results. The proton FLASH sparing effect on CL was observed. In single-fraction PBS FLASH, just 1.5% of peripheral blood was irradiated, whereas hypofractionated FLASH irradiated 7.3% of peripheral blood. In contrast, conventional fractionated IMPT exposed 42.4% of peripheral blood to radiation. PBS FLASH reduced the depletion rate of CL by 69.2% when compared to conventional fractionated IMPT.Conclusion. Our dosimetric blood flow model provides quantitative measures of the PBS FLASH sparing effect on the CL in radiotherapy for brain cancer. FLASH Single treatment fraction offers superior CL sparing when compared to hypofractionated FLASH and conventional IMPT, supporting assumptions about reducing risks of lymphopenia compared to proton therapy at conventional dose rates. The results also indicate that faster conformal FLASH delivery, such as passive patient-specific energy modulation, may further enhance the sparing of the immune system.
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Liu G, Zhao L, Li X, Zhang S, Dai S, Lu X, Ding X. A Novel Ultrahigh-Dose-Rate Proton Therapy Technology: Spot-Scanning Proton Arc Therapy + FLASH (SPLASH). Int J Radiat Oncol Biol Phys 2023; 117:730-737. [PMID: 37196836 DOI: 10.1016/j.ijrobp.2023.05.012] [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: 12/05/2022] [Revised: 04/10/2023] [Accepted: 05/08/2023] [Indexed: 05/19/2023]
Abstract
PURPOSE To take full advantage of FLASH dose rate (40 Gy/s) and high-dose conformity, we introduce a novel optimization and delivery technique, the spot-scanning proton arc therapy (SPArc) + FLASH (SPLASH). METHODS AND MATERIALS SPLASH framework was implemented in an open-source proton planning platform (MatRad, Department of Medical Physics in Radiation Oncology, German Cancer Research Center). It optimizes with the clinical dose-volume constraint based on dose distribution and the dose-average dose rate by minimizing the monitor unit constraint on spot weight and accelerator beam current sequentially, enabling the first dynamic arc therapy with voxel-based FLASH dose rate. This new optimization framework minimizes the overall cost function value combined with plan quality and voxel-based dose-rate constraints. Three representative cases (brain, liver, and prostate cancer) were used for testing purposes. Dose-volume histogram, dose-rate-volume histogram, and dose-rate map were compared among intensity modulated proton radiation therapy (IMPT), SPArc, and SPLASH. RESULTS SPLASH/SPArc could offer superior plan quality over IMPT in terms of dose conformity. The dose-rate-volume histogram results indicated SPLASH could significantly improve V40 Gy/s in the target and region of interest for all tested cases compared with SPArc and IMPT. The optimal beam current per spot is simultaneously generated, which is within the existing proton machine specifications in the research version (<200 nA). CONCLUSIONS SPLASH offers the first voxel-based ultradose-rate and high-dose conformity treatment using proton beam therapy. Such a technique has the potential to fit the needs of a broad range of disease sites and simplify clinical workflow without applying a patient-specific ridge filter, which has never before been demonstrated.
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Affiliation(s)
- Gang Liu
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430023 China.
| | - Lewei Zhao
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan
| | - Xiaoqiang Li
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan
| | - Sheng Zhang
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430023 China.
| | - Shuyang Dai
- School of Mathematics and Statistics, Wuhan University, Wuhan 430072 China
| | - Xiliang Lu
- School of Mathematics and Statistics, Wuhan University, Wuhan 430072 China
| | - Xuanfeng Ding
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan.
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15
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Deffet S, Hamaide V, Sterpin E. Definition of dose rate for FLASH pencil-beam scanning proton therapy: A comparative study. Med Phys 2023; 50:5784-5792. [PMID: 37439504 DOI: 10.1002/mp.16607] [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: 03/28/2023] [Revised: 05/28/2023] [Accepted: 06/20/2023] [Indexed: 07/14/2023] Open
Abstract
BACKGROUND FLASH proton therapy has the potential to reduce side effects of conventional proton therapy by delivering a high dose of radiation in a very short period of time. However, significant progress is needed in the development of FLASH proton therapy. Increasing the dose rate while maintaining dose conformality may involve the use of advanced beam-shaping technologies and specialized equipment such as 3D patient-specific range modulators, to take advantage of the higher transmission efficiency at the highest energy available. The dose rate is an important factor in FLASH proton therapy, but its definition can vary because of the uneven distribution of the dose over time in pencil-beam scanning (PBS). PURPOSE Highlight the distinctions, both in terms of concept and numerical values, of the various definitions that can be established for the dose rate in PBS proton therapy. METHODS In an in silico study, five definitions of the dose rate, namely the PBS dose rate, the percentile dose rate, the maximum percentile dose rate, the average dose rate, and the dose averaged dose rate (DADR) were analyzed first through theoretical comparison, and then applied to a head and neck case. To carry out this study, a treatment plan utilizing a single energy level and requiring the use of a patient-specific range modulator was employed. The dose rate values were compared both locally and by means of dose rate volume histograms (DRVHs). RESULTS The PBS dose rate, the percentile dose rate, and the maximum percentile dose are definitions that are specifically designed to take into account the time structure of the delivery of a PBS treatment plan. Although they may appear similar, our study shows that they can vary locally by up to 10%. On the other hand, the DADR values were approximately twice as high as those of the PBS, percentile, and maximum percentile dose rates, since the DADR disregards the periods when a voxel does not receive any dose. Finally, the average dose rate can be defined in various ways, as discussed in this paper. The average dose rate is found to be lower by a factor of approximately 1/2 than the PBS, percentile, and maximum percentile dose rates. CONCLUSIONS We have shown that using different definitions for the dose rate in FLASH proton therapy can lead to variations in calculated values ranging from a few percent to a factor of two. Since the dose rate is a critical parameter in FLASH radiation therapy, it is essential to carefully consider the choice of definition. However, to make an informed decision, additional biological data and models are needed.
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Affiliation(s)
- Sylvain Deffet
- Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain, Louvain-La-Neuve, Belgium
| | | | - Edmond Sterpin
- Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain, Louvain-La-Neuve, Belgium
- Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven, Leuven, Belgium
- Particle Therapy Interuniversity Center Leuven-PARTICLE, Leuven, Belgium
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van Marlen P, van de Water S, Dahele M, Slotman BJ, Verbakel WFAR. Single Ultra-High Dose Rate Proton Transmission Beam for Whole Breast FLASH-Irradiation: Quantification of FLASH-Dose and Relation with Beam Parameters. Cancers (Basel) 2023; 15:cancers15092579. [PMID: 37174045 PMCID: PMC10177419 DOI: 10.3390/cancers15092579] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/25/2023] [Accepted: 04/27/2023] [Indexed: 05/15/2023] Open
Abstract
Healthy tissue-sparing effects of FLASH (≥40 Gy/s, ≥4-8 Gy/fraction) radiotherapy (RT) make it potentially useful for whole breast irradiation (WBI), since there is often a lot of normal tissue within the planning target volume (PTV). We investigated WBI plan quality and determined FLASH-dose for various machine settings using ultra-high dose rate (UHDR) proton transmission beams (TBs). While five-fraction WBI is commonplace, a potential FLASH-effect might facilitate shorter treatments, so hypothetical 2- and 1-fraction schedules were also analyzed. Using one tangential 250 MeV TB delivering 5 × 5.7 Gy, 2 × 9.74 Gy or 1 × 14.32 Gy, we evaluated: (1) spots with equal monitor units (MUs) in a uniform square grid with variable spacing; (2) spot MUs optimized with a minimum MU-threshold; and (3) splitting the optimized TB into two sub-beams: one delivering spots above an MU-threshold, i.e., at UHDRs; the other delivering the remaining spots necessary to improve plan quality. Scenarios 1-3 were planned for a test case, and scenario 3 was also planned for three other patients. Dose rates were calculated using the pencil beam scanning dose rate and the sliding-window dose rate. Various machine parameters were considered: minimum spot irradiation time (minST): 2 ms/1 ms/0.5 ms; maximum nozzle current (maxN): 200 nA/400 nA/800 nA; two gantry-current (GC) techniques: energy-layer and spot-based. For the test case (PTV = 819 cc) we found: (1) a 7 mm grid achieved the best balance between plan quality and FLASH-dose for equal-MU spots; (2) near the target boundary, lower-MU spots are necessary for homogeneity but decrease FLASH-dose; (3) the non-split beam achieved >95% FLASH for favorable (not clinically available) machine parameters (SB GC, low minST, high maxN), but <5% for clinically available settings (EB GC, minST = 2 ms, maxN = 200 nA); and (4) splitting gave better plan quality and higher FLASH-dose (~50%) for available settings. The clinical cases achieved ~50% (PTV = 1047 cc) or >95% (PTV = 477/677 cc) FLASH after splitting. A single UHDR-TB for WBI can achieve acceptable plan quality. Current machine parameters limit FLASH-dose, which can be partially overcome using beam-splitting. WBI FLASH-RT is technically feasible.
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Affiliation(s)
- Patricia van Marlen
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
| | - Steven van de Water
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
| | - Max Dahele
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
| | - Berend J Slotman
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
| | - Wilko F A R Verbakel
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
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Gaito S, Marvaso G, Ortiz R, Crellin A, Aznar MC, Indelicato DJ, Pan S, Whitfield G, Alongi F, Jereczek-Fossa BA, Burnet N, Li MP, Rothwell B, Smith E, Colaco RJ. Proton Beam Therapy in the Oligometastatic/Oligorecurrent Setting: Is There a Role? A Literature Review. Cancers (Basel) 2023; 15:cancers15092489. [PMID: 37173955 PMCID: PMC10177340 DOI: 10.3390/cancers15092489] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
BACKGROUND Stereotactic ablative radiotherapy (SABR) and stereotactic radiosurgery (SRS) with conventional photon radiotherapy (XRT) are well-established treatment options for selected patients with oligometastatic/oligorecurrent disease. The use of PBT for SABR-SRS is attractive given the property of a lack of exit dose. The aim of this review is to evaluate the role and current utilisation of PBT in the oligometastatic/oligorecurrent setting. METHODS Using Medline and Embase, a comprehensive literature review was conducted following the PICO (Patients, Intervention, Comparison, and Outcomes) criteria, which returned 83 records. After screening, 16 records were deemed to be relevant and included in the review. RESULTS Six of the sixteen records analysed originated in Japan, six in the USA, and four in Europe. The focus was oligometastatic disease in 12, oligorecurrence in 3, and both in 1. Most of the studies analysed (12/16) were retrospective cohorts or case reports, two were phase II clinical trials, one was a literature review, and one study discussed the pros and cons of PBT in these settings. The studies presented in this review included a total of 925 patients. The metastatic sites analysed in these articles were the liver (4/16), lungs (3/16), thoracic lymph nodes (2/16), bone (2/16), brain (1/16), pelvis (1/16), and various sites in 2/16. CONCLUSIONS PBT could represent an option for the treatment of oligometastatic/oligorecurrent disease in patients with a low metastatic burden. Nevertheless, due to its limited availability, PBT has traditionally been funded for selected tumour indications that are defined as curable. The availability of new systemic therapies has widened this definition. This, together with the exponential growth of PBT capacity worldwide, will potentially redefine its commissioning to include selected patients with oligometastatic/oligorecurrent disease. To date, PBT has been used with encouraging results for the treatment of liver metastases. However, PBT could be an option in those cases in which the reduced radiation exposure to normal tissues leads to a clinically significant reduction in treatment-related toxicities.
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Affiliation(s)
- Simona Gaito
- Proton Clinical Outcomes Unit, The Christie NHS Proton Beam Therapy Centre, Manchester M20 4BX, UK
- Division of Clinical Cancer Science, School of Medical Sciences, The University of Manchester, Manchester M13 9PL, UK
| | - Giulia Marvaso
- Department of Oncology and Hemato-Oncology, University of Milan, 20122 Milan, Italy
- Department of Radiation Oncology, IEO European Institute of Oncology IRCCS, 20126 Milan, Italy
| | - Ramon Ortiz
- Department of Radiation Oncology, University of California, San Francisco, CA 94720, USA
| | - Adrian Crellin
- National Lead Proton Beam Therapy NHSe, Manchester M20 4BX, UK
| | - Marianne C Aznar
- Division of Clinical Cancer Science, School of Medical Sciences, The University of Manchester, Manchester M13 9PL, UK
| | - Daniel J Indelicato
- Department of Radiation Oncology, University of Florida, Jacksonville, FL 32206, USA
| | - Shermaine Pan
- Department of Proton Beam Therapy, The Christie Proton Beam Therapy Centre, Manchester M20 3DA, UK
| | - Gillian Whitfield
- Division of Clinical Cancer Science, School of Medical Sciences, The University of Manchester, Manchester M13 9PL, UK
- Department of Proton Beam Therapy, The Christie Proton Beam Therapy Centre, Manchester M20 3DA, UK
| | - Filippo Alongi
- Advanced Radiation Oncology Department, IRCCS Ospedale Sacro Cuore don Calabria, 37024 Verona, Italy
- Division of Radiology and Radiotherapy, University of Brescia, 25121 Brescia, Italy
| | - Barbara Alicja Jereczek-Fossa
- Department of Oncology and Hemato-Oncology, University of Milan, 20122 Milan, Italy
- Department of Radiation Oncology, IEO European Institute of Oncology IRCCS, 20126 Milan, Italy
| | - Neil Burnet
- Department of Proton Beam Therapy, The Christie Proton Beam Therapy Centre, Manchester M20 3DA, UK
| | - Michelle P Li
- Department of Proton Beam Therapy, The Christie Proton Beam Therapy Centre, Manchester M20 3DA, UK
- Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Bethany Rothwell
- Division of Physics, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Ed Smith
- Proton Clinical Outcomes Unit, The Christie NHS Proton Beam Therapy Centre, Manchester M20 4BX, UK
- Division of Clinical Cancer Science, School of Medical Sciences, The University of Manchester, Manchester M13 9PL, UK
- Department of Proton Beam Therapy, The Christie Proton Beam Therapy Centre, Manchester M20 3DA, UK
| | - Rovel J Colaco
- Department of Proton Beam Therapy, The Christie Proton Beam Therapy Centre, Manchester M20 3DA, UK
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Vozenin MC, Schüller A, Dutreix M, Kirkby K, Baumann M, Coppes RP, Thwaites D. FLASH Radiotherapy & Particle Therapy conference, FRPT2021. Radiother Oncol 2022; 175:167-168. [DOI: 10.1016/j.radonc.2022.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 09/20/2022] [Indexed: 11/05/2022]
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