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Oliaei Motlagh SA, Vander Stappen F, Kim MM, Labarbe R, Hotoiu L, Pin A, Nilsson R, Traneus E, Cengel KA, Zou W, Teo BKK, Dong L, Diffenderfer ES. Verification of dose and dose rate for quality assurance of spread-out-Bragg-peak proton FLASH radiotherapy using machine log files. Med Phys 2025; 52:5005-5016. [PMID: 40170430 DOI: 10.1002/mp.17792] [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: 08/05/2024] [Revised: 03/02/2025] [Accepted: 03/18/2025] [Indexed: 04/03/2025] Open
Abstract
BACKGROUND Ultra-high dose rate radiotherapy elicits a biological effect (FLASH), which has been shown to reduce toxicity while maintaining tumor control in preclinical radiobiology experiments. FLASH depends on the dose rate, with evidence that higher dose rates drive increased normal tissue sparing. The pattern of dose delivery also has significance for conformal proton FLASH delivered via pencil beam scanning (PBS) given its unique spatio-temporal distribution of dose deposition. PURPOSE In PBS, the machine-generated log file contains information on the spatio-temporal pattern of PBS delivery measured by the segmented ionization chambers in the treatment nozzle. The spot position and monitor unit (MU) obtained from log files have previously been used to reconstruct the treatment dose by Monte Carlo (MC) simulations. The incorporation of spot timing allows reconstruction of the 3D temporal dose distribution. The log-based dose and dose rate can have a role in quality assurance (QA) and FLASH treatment verification if the reconstruction can be shown to be accurate in spatial and temporal domains of dose deposition. Thus, the objective of this study is to validate the accuracy of dose rate reconstruction using input data from machine log files of PBS delivery. By analyzing the delivered spot timing, position, and MU extracted from the logs, we aim to evaluate the reliability and precision of the log data for dose and dose rate reconstruction. METHODS FLASH PBS spread-out Bragg peak (SOBP) treatment fields were delivered using a cyclotron accelerated proton beam. This method involves a patient and field-specific conformal energy modulator (CEM) to achieve a SOBP at the tumor site. Log files record spot positions and the delivered MU with timing information at 250 µs resolution. To validate timing information, a 9.9 mm diameter parallel plate ionization chamber was positioned at various locations within the SOBP. An electrometer sampling at 20 kHz recorded the time-resolved ionization current collected by the ionization chamber. These measurements were used to determine spot dose, dose rate, duration, and transition times. Disparities between the measured and logged spot map MU and timing were determined. Dose average and PBS dose rates were compared between the measurement and log-based MC simulations. RESULTS There was a good agreement between the measured dwell time and transition time and the logged information across various detector positions. The median disparities for inter-spot dwell time range from -0.041 to 0.024 ms. Differences between logged and planned spot positions are minimal, measuring less than 1.08 mm in the x direction and 1.15 mm in the y direction, consistent with prior studies and the spatial resolution of the PBS nozzle ionization chamber. Delivered MU were within 1.9% of the planned MU. Measured dose and dose rates are consistent with simulated outcomes derived from MC simulation. CONCLUSION We validated the precision and accuracy of PBS log file data through measurements and MC simulations. These findings support the use of log files in MC calculations as one part of patient-specific quality assurance (PSQA) and dose rate delivery verification for conformal proton FLASH radiotherapy with SOBP.
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Affiliation(s)
| | | | - Michele M Kim
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rudi Labarbe
- Ion Beam Applications S.A, (IBA), Luvain-la-Neueve, Belgium
| | - Lucian Hotoiu
- Ion Beam Applications S.A, (IBA), Luvain-la-Neueve, Belgium
| | - Arnaud Pin
- Ion Beam Applications S.A, (IBA), Luvain-la-Neueve, Belgium
| | | | | | - Keith A Cengel
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wei Zou
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Boon-Keng Kevin Teo
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Lei Dong
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Eric S Diffenderfer
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Setianegara J, Wang A, Gerard N, Nys J, Harold Li H, Chen RC, Gao H, Lin Y. Characterization of commercial detectors for absolute proton UHDR dosimetry on a compact clinical proton synchrocyclotron. Med Phys 2025. [PMID: 40268691 DOI: 10.1002/mp.17847] [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: 09/24/2024] [Revised: 04/04/2025] [Accepted: 04/05/2025] [Indexed: 04/25/2025] Open
Abstract
BACKGROUND Modern compact proton synchrocyclotrons can achieve ultra-high dose rates ( ≥ $ \ge $ 40 Gy/s) to support ultra-high-dose-rate (UHDR) preclinical experiments utilizing pencil beam scanning (PBS) protons. Unique to synchrocyclotrons is a pulsed proton time structure as compared to the quasi-continuous nature of other proton accelerators like isochronous cyclotrons. Thus, high instantaneous proton currents in the order of several µA must be generated to achieve UHDRs. This will lead to high doses-per-pulse (DPP), which may cause significant charge recombination for ionization chambers, which must be characterized for accurate UHDR dosimetry programs. PURPOSE In this work, we investigate the suitability of various commercial radiation detectors for accurate proton UHDR dosimetry using PBS proton beams from a compact proton synchrocyclotron (IBA ProteusONE). This is achieved by cross-calibrating them with conventional dose rates, measuring UHDR recombination (Pion) and polarity correction factors (Ppol) for ionization chambers, and determining the absorbed proton UHDR dose delivered for all detectors. METHODS An IBA ProteusONE synchrocyclotron was initially tuned to achieve UHDRs with 228 MeV protons at 0° gantry angle. Various detectors, including Razor Chamber, Razor Nano Chamber, Razor Diode, and microDiamond, were cross-calibrated against a PPC05 plane-parallel ionization chamber (PPIC) that had an ADCL calibration coefficient of 59.23 cGy/nC. Then, all ionization chambers were exposed to UHDR protons with the Ppol and Pion subsequently calculated. Pion was calculated using two methods: TRS-398 methods and Niatel's model. Finally, the absolute UHDR proton doses delivered were determined for all detectors and cross-compared. RESULTS Faraday cup measurements were performed for a single spot proton UHDR beam, and the nozzle current at the isocenter was determined to be 129.5 nA during UHDR irradiations at 98.61% of the maximum theoretical dose rate. Repeated Faraday cup measurements of the UHDR beam yielded a percentage standard deviation of 0.8%, which was higher than 0.120% when similar repeated measurements were performed with conventional proton beams. Ppol was found to be relatively dose-rate independent for all ionization chambers investigated. Pion was found to be the lowest for the PPC05 ionization chamber (1.0097) compared to corresponding values of 1.0214 and 1.0294 for the Razor and Razor Nano detectors, respectively, for UHDRs. Pion values calculated using Niatel's model closely matched values from TRS-398 if the VH/VL ratio were kept at 2.5 for the PPC05 and Razor detectors and 2.0 for the Razor Nano detector. Absolute proton UHDR doses determined using cross-calibration factors were generally within ± 1% of PPC05 measurements. However, Razor Diode was found to over-respond by up to 3.79% within UHDR proton beams, rendering them unsuitable for proton UHDR dosimetry. CONCLUSION In this work, we comprehensively evaluated the suitability of various commercial detectors for absolute dosimetry with a pulsed UHDR beam structure from a proton synchrocyclotron. PPC05 had the lowest ionic recombination correction compared to Razor and Razor Nano ion chambers. Other than the diode detector, all other investigated detectors (PPC05, Razor, Razor Nano, microDiamond) were within ± 1% of one another and can be used for accurate absolute proton UHDR dosimetry.
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Affiliation(s)
- Jufri Setianegara
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Aoxiang Wang
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, Kansas, USA
- Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan, China
| | | | - Jarrick Nys
- Ion Beam Applications (IBA), Louvain-la-Neuve, Belgium
| | - H Harold Li
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Ronald C Chen
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Hao Gao
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Yuting Lin
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, Kansas, USA
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Alhaddad L, Osipov AN, Leonov S. FLASH Radiotherapy: Benefits, Mechanisms, and Obstacles to Its Clinical Application. Int J Mol Sci 2024; 25:12506. [PMID: 39684218 DOI: 10.3390/ijms252312506] [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: 10/08/2024] [Revised: 11/14/2024] [Accepted: 11/17/2024] [Indexed: 12/18/2024] Open
Abstract
Radiotherapy (RT) has been shown to be a cornerstone of both palliative and curative tumor care. RT has generally been reported to be sharply limited by ionizing radiation (IR)-induced toxicity, thereby constraining the control effect of RT on tumor growth. FLASH-RT is the delivery of ultra-high dose rate (UHDR) several orders of magnitude higher than what is presently used in conventional RT (CONV-RT). The FLASH-RT clinical trials have been designed to examine the UHDR deliverability, the effectiveness of tumor control, the dose tolerance of normal tissue, and the reproducibility of treatment effects across several institutions. Although it is still in its infancy, FLASH-RT has been shown to have potential to rival current RT in terms of safety. Several studies have suggested that the adoption of FLASH-RT is very limited, and the incorporation of this new technique into routine clinical RT will require the use of accurate dosimetry methods and reproducible equipment that enable the reliable and robust measurements of doses and dose rates. The purpose of this review is to highlight the advantages of this technology, the potential mechanisms underpinning the FLASH-RT effect, and the major challenges that need to be tackled in the clinical transfer of FLASH-RT.
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Affiliation(s)
- Lina Alhaddad
- Department of Environmental Sciences, Faculty of Science, Damascus University, Damascus P.O. Box 30621, Syria
| | - Andreyan N Osipov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow 119991, Russia
- Moscow Center for Advanced Studies, Kulakova Str. 20, Moscow 123592, Russia
- State Research Center-Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency (SRC-FMBC), Moscow 123098, Russia
- CANDLE Synchrotron Research Institute, 31 Acharyan, Yerevan 0040, Armenia
| | - Sergey Leonov
- Moscow Center for Advanced Studies, Kulakova Str. 20, Moscow 123592, Russia
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino 142290, Russia
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van Marlen P, van de Water S, Slotman BJ, Dahele M, Verbakel W. Technical note: Dosimetry and FLASH potential of UHDR proton PBS for small lung tumors: Bragg-peak-based delivery versus transmission beam and IMPT. Med Phys 2024; 51:7580-7588. [PMID: 38795376 DOI: 10.1002/mp.17185] [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: 11/22/2023] [Revised: 04/19/2024] [Accepted: 05/04/2024] [Indexed: 05/27/2024] Open
Abstract
BACKGROUND High-energy transmission beams (TBs) are currently the main delivery method for proton pencil beam scanning ultrahigh dose-rate (UHDR) FLASH radiotherapy. TBs place the Bragg-peaks behind the target, outside the patient, making delivery practical and achievement of high dose-rates more likely. However, they lead to higher integral dose compared to conventional intensity-modulated proton therapy (IMPT), in which Bragg-peaks are placed within the tumor. It is hypothesized that, when energy changes are not required and high beam currents are possible, Bragg-peak-based beams can not only achieve more conformal dose distributions than TBs, but also have more FLASH-potential. PURPOSE This works aims to verify this hypothesis by taking three different Bragg-peak-based delivery techniques and comparing them with TB and IMPT-plans in terms of dosimetry and FLASH-potential for single-fraction lung stereotactic body radiotherapy (SBRT). METHODS For a peripherally located lung target of various sizes, five different proton plans were made using "matRad" and inhouse-developed algorithms for spot/energy-layer/beam reduction and minimum monitor unit maximization: (1) IMPT-plan, reference for dosimetry, (2) TB-plan, reference for FLASH-amount, (3) pristine Bragg-peak plan (non-depth-modulated Bragg-peaks), (4) Bragg-peak plan using generic ridge filter, and (5) Bragg-peak plan using 3D range-modulated ridge filter. RESULTS Bragg-peak-based plans are able to achieve sufficient plan quality and high dose-rates. IMPT-plans resulted in lowest OAR-dose and integral dose (also after a FLASH sparing-effect of 30%) compared to both TB-plans and Bragg-peak-based plans. Bragg-peak-based plans vary only slightly between themselves and generally achieve lower integral dose than TB-plans. However, TB-plans nearly always resulted in lower mean lung dose than Bragg-peak-based plans and due to a higher amount of FLASH-dose for TB-plans, this difference increased after including a FLASH sparing-effect. CONCLUSION This work indicates that there is no benefit in using Bragg-peak-based beams instead of TBs for peripherally located, UHDR stereotactic lung radiotherapy, if lung dose is the priority.
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Affiliation(s)
- Patricia van Marlen
- Department of Radiation Oncology, Amsterdam UMC, Cancer Center Amsterdam, Amsterdam, the Netherlands
| | - Steven van de Water
- Department of Radiation Oncology, Amsterdam UMC, Cancer Center Amsterdam, Amsterdam, the Netherlands
| | - Ben J Slotman
- Department of Radiation Oncology, Amsterdam UMC, Cancer Center Amsterdam, Amsterdam, the Netherlands
| | - Max Dahele
- Department of Radiation Oncology, Amsterdam UMC, Cancer Center Amsterdam, Amsterdam, the Netherlands
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Zeng Y, Li H, Zhang Q, Wang W, Liu X, Qin B, Pang B, Liu M, Yang K, Quan H, Chang Y, Yang Z. Biological-equivalent-dose-based integrated optimization framework for fast-energy-switching Bragg peak FLASH-RT using single-beam-per-fraction. Med Phys 2024; 51:6292-6304. [PMID: 39031641 DOI: 10.1002/mp.17264] [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: 01/24/2024] [Revised: 05/27/2024] [Accepted: 06/09/2024] [Indexed: 07/22/2024] Open
Abstract
BACKGROUNDS When comparing the delivery of all beams per fraction (ABPF) to single beam per fraction (SBPF), it is observed that SBPF not only helps meet the FLASH dose threshold but also mitigates the uncertainty with beam switching in the FLASH effect. However, SBPF might lead to a higher biological equivalent dose in 2 Gy (EQD2) for normal tissues. PURPOSE This study aims to develop an EQD2-based integrated optimization framework (EQD2-IOF), encompassing robust dose, delivery efficiency, and beam orientation optimization (BOO) for Bragg peak FLASH plans using the SBPF treatment schedule. The EQD2-IOF aims to enhance both dose sparing and the FLASH effect. METHODS A superconducting gantry was employed for fast energy switching within 27 ms, while universal range shifters were utilized to improve beam current in the implementation of FLASH plans with five Bragg peak beams. To enhance dose delivery efficiency while maintaining plan quality, a simultaneous dose and spot map optimization (SDSMO) algorithm for single field optimization was incorporated into a Bayesian optimization-based auto-planning algorithm. Subsequently, a BOO algorithm based on Tabu search was developed to select beam angle combinations (BACs) for 10 lung cases. To simultaneously consider dose sparing and FLASH effect, a quantitative model based on dose-dependent dose modification factor (DMF) was used to calculate FLASH-enhanced dose distribution. The EQD2-IOF plan was compared to the plan optimized without SDSMO using BAC selected by a medical physicist (Manual plan) in the SBPF treatment schedule. Meanwhile, the mean EQD2 in the normal tissue was evaluated for the EQD2-IOF plan in both SBPF and ABPF treatment schedules. RESULTS No significant difference was found in D2% and D98% of the target between EQD2-IOF plans and Manual Plans. When using a minimum DMF of 0.67 and a dose threshold of 4 Gy, EQD2-IOF plans showed a significant reduction in FLASH-enhanced EQD2mean of the ipsilateral lung and normal tissue by 10.5% and 11.5%, respectively, compared to Manual plans. For normal tissues that received a dose greater than 70% of the prescription dose, using a minimum DMF of 0.7 for FLASH sparing compensated for the increase in EQD2mean resulting from replacing ABPF with SBPF schedules. CONCLUSIONS The EQD2-IOF can automatically optimize SBPF FLASH-RT plans to achieve optimal sparing of normal tissues. With an energy switching time of 27 ms, the loss of fractionate repairing using SBPF schedules in high-dose regions can be compensated for by the FLASH effect. However, when an energy switching time of 500 ms is utilized, the SBPF schedule needs careful consideration, as the FLASH effect diminishes with longer irradiation time.
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Affiliation(s)
- Yiling Zeng
- Department of Medical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Precision Radiation Oncology, Wuhan, China
| | - Heng Li
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, Maryland, USA
| | - Qi Zhang
- Department of Medical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Wei Wang
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Xu Liu
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Bin Qin
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Bo Pang
- Department of Medical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Muyu Liu
- Department of Medical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Kunyu Yang
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Precision Radiation Oncology, Wuhan, China
| | - Hong Quan
- Department of Medical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Yu Chang
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Precision Radiation Oncology, Wuhan, China
| | - Zhiyong Yang
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Precision Radiation Oncology, Wuhan, China
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Kong W, Huiskes M, Habraken SJM, Astreinidou E, Rasch CRN, Heijmen BJM, Breedveld S. Reducing the lateral dose penumbra in IMPT by incorporating transmission pencil beams. Radiother Oncol 2024; 198:110388. [PMID: 38897315 DOI: 10.1016/j.radonc.2024.110388] [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: 04/04/2024] [Revised: 05/30/2024] [Accepted: 06/13/2024] [Indexed: 06/21/2024]
Abstract
OBJECTIVE In intensity-modulated proton therapy (IMPT), Bragg peaks result in steep distal dose fall-offs, while the lateral IMPT dose fall-off is often less steep than in photon therapy. High-energy pristine transmission ('shoot through') pencil beams have no Bragg peak in the patient, but show a sharp lateral penumbra at the target level. We investigated whether combining Bragg peaks with Transmission pencil beams ('IMPT&TPB') could improve head-and-neck plans by exploiting the steep lateral dose fall-off of transmission pencil beams. APPROACH Our system for automated multi-criteria IMPT plan optimisation was extended for combined optimisation of BPs and TPBs. The system generates for each patient a Pareto-optimal plan using a generic 'wish-list' with prioritised planning objectives and hard constraints. For eight nasopharynx cancer patients (NPC) and eight oropharynx cancer (OPC) patients, the IMPT&TPB plan was compared to the competing conventional IMPT plan with only Bragg peaks, which was generated with the same optimiser, but without transmission pencil beams. MAIN RESULTS Clinical OAR and target constraints were met in all plans. By allowing transmission pencil beams in the optimisation, on average 14 of the 25 investigated OAR plan parameters significantly improved for NPC, and 9 of the 17 for OPC, while only one OPC parameter showed small but significant deterioration. Non-significant differences were found in the remaining parameters. In NPC, cochlea Dmean reduced by up to 17.5 Gy and optic nerve D2% by up to 11.1 Gy. CONCLUSION Compared to IMPT, IMPT&TPB resulted in comparable target coverage with overall superior OAR sparing, the latter originating from steeper dose fall-offs close to OARs.
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Affiliation(s)
- W Kong
- Department of Radiotherapy, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands.
| | - M Huiskes
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands
| | - S J M Habraken
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands; HollandPTC, Delft, the Netherlands
| | - E Astreinidou
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands
| | - C R N Rasch
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands; HollandPTC, Delft, the Netherlands
| | - B J M Heijmen
- Department of Radiotherapy, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - S Breedveld
- Department of Radiotherapy, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
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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: 1.5] [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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Chauhan RS, Pradhan A, Munshi A, Mohanti BK. Efficient and Reliable Data Extraction in Radiation Oncology using Python Programming Language: A Pilot Study. J Med Phys 2023; 48:13-18. [PMID: 37342597 PMCID: PMC10277304 DOI: 10.4103/jmp.jmp_12_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/27/2023] [Accepted: 03/02/2023] [Indexed: 06/23/2023] Open
Abstract
Background and Purpose In recent years, data science approaches have entered health-care systems such as radiology, pathology, and radiation oncology. In our pilot study, we developed an automated data mining approach to extract data from a treatment planning system (TPS) with high speed, maximum accuracy, and little human interaction. We compared the amount of time required for manual data extraction versus the automated data mining technique. Materials and Methods A Python programming script was created to extract specified parameters and features pertaining to patients and treatment (a total of 25 features) from TPS. We successfully implemented automation in data mining, utilizing the application programming interface environment provided by the external beam radiation therapy equipment provider for the whole group of patients who were accepted for treatment. Results This in-house Python-based script extracted selected features for 427 patients in 0.28 ± 0.03 min with 100% accuracy at an astonishing rate of 0.04 s/plan. Comparatively, manual extraction of 25 parameters took an average of 4.5 ± 0.33 min/plan, along with associated transcriptional and transpositional errors and missing data information. This new approach turned out to be 6850 times faster than the conventional approach. Manual feature extraction time increased by a factor of nearly 2.5 if we doubled the number of features extracted, whereas for the Python script, it increased by a factor of just 1.15. Conclusion We conclude that our in-house developed Python script can extract plan data from TPS at a far higher speed (>6000 times) and with the best possible accuracy compared to manual data extraction.
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Affiliation(s)
- Rohit Singh Chauhan
- Department of Physics, GLA University, Mathura, Uttar Pradesh, India
- Department of Radiation Oncology, Manipal Hospitals, Dwarka, New Delhi, India
| | - Anirudh Pradhan
- Centre for Cosmology, Astrophysics and Space Science, GLA University, Mathura, Uttar Pradesh, India
| | - Anusheel Munshi
- Department of Radiation Oncology, Manipal Hospitals, Dwarka, New Delhi, India
| | - Bidhu Kalyan Mohanti
- KIMS Cancer Centre, Kalinga Institute of Medical Sciences, KIIT University, Bhubaneswar, Odisha, India
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Mascia AE, Daugherty EC, Zhang Y, Lee E, Xiao Z, Sertorio M, Woo J, Backus LR, McDonald JM, McCann C, Russell K, Levine L, Sharma RA, Khuntia D, Bradley JD, Simone CB, Perentesis JP, Breneman JC. Proton FLASH Radiotherapy for the Treatment of Symptomatic Bone Metastases: The FAST-01 Nonrandomized Trial. JAMA Oncol 2023; 9:62-69. [PMID: 36273324 PMCID: PMC9589460 DOI: 10.1001/jamaoncol.2022.5843] [Citation(s) in RCA: 142] [Impact Index Per Article: 71.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 09/26/2022] [Indexed: 01/24/2023]
Abstract
Importance To our knowledge, there have been no clinical trials of ultra-high-dose-rate radiotherapy delivered at more than 40 Gy/sec, known as FLASH therapy, nor first-in-human use of proton FLASH. Objectives To assess the clinical workflow feasibility and treatment-related toxic effects of FLASH and pain relief at the treatment sites. Design, Setting, and Participants In the FAST-01 nonrandomized trial, participants treated at Cincinnati Children's/UC Health Proton Therapy Center underwent palliative FLASH radiotherapy to extremity bone metastases. Patients 18 years and older with 1 to 3 painful extremity bone metastases and life expectancies of 2 months or more were eligible. Patients were excluded if they had foot, hand, and wrist metastases; metastases locally treated in the 2 weeks prior; metal implants in the treatment field; known enhanced tissue radiosensitivity; and implanted devices at risk of malfunction with radiotherapy. One of 11 patients who consented was excluded based on eligibility. The end points were evaluated at 3 months posttreatment, and patients were followed up through death or loss to follow-up for toxic effects and pain assessments. Of the 10 included patients, 2 died after the 2-month follow-up but before the 3-month follow-up; 8 participants completed the 3-month evaluation. Data were collected from November 3, 2020, to January 28, 2022, and analyzed from January 28, 2022, to September 1, 2022. Interventions Bone metastases were treated on a FLASH-enabled (≥40 Gy/sec) proton radiotherapy system using a single-transmission proton beam. This is consistent with standard of care using the same prescription (8 Gy in a single fraction) but on a conventional-dose-rate (approximately 0.03 Gy/sec) photon radiotherapy system. Main Outcome and Measures Main outcomes included patient time on the treatment couch, device-related treatment delays, adverse events related to FLASH, patient-reported pain scores, and analgesic use. Results A total of 10 patients (age range, 27-81 years [median age, 63 years]; 5 [50%] male) underwent FLASH radiotherapy at 12 metastatic sites. There were no FLASH-related technical issues or delays. The average (range) time on the treatment couch was 18.9 (11-33) minutes per patient and 15.8 (11-22) minutes per treatment site. Median (range) follow-up was 4.8 (2.3-13.0) months. Adverse events were mild and consistent with conventional radiotherapy. Transient pain flares occurred in 4 of the 12 treated sites (33%). In 8 of the 12 sites (67%) patients reported pain relief, and in 6 of the 12 sites (50%) patients reported a complete response (no pain). Conclusions and Relevance In this nonrandomized trial, clinical workflow metrics, treatment efficacy, and safety data demonstrated that ultra-high-dose-rate proton FLASH radiotherapy was clinically feasible. The treatment efficacy and the profile of adverse events were comparable with those of standard-of-care radiotherapy. These findings support the further exploration of FLASH radiotherapy in patients with cancer. Trial Registration ClinicalTrials.gov Identifier: NCT04592887.
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Affiliation(s)
- Anthony E. Mascia
- Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital, Cincinnati, Ohio
- Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Emily C. Daugherty
- Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital, Cincinnati, Ohio
- Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Yongbin Zhang
- Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital, Cincinnati, Ohio
- Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Eunsin Lee
- Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital, Cincinnati, Ohio
- Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Zhiyan Xiao
- Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital, Cincinnati, Ohio
- Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Mathieu Sertorio
- Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Jennifer Woo
- Varian Medical Systems, Siemens Healthineers, Palo Alto, California
| | - Lori R. Backus
- Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital, Cincinnati, Ohio
| | - Julie M. McDonald
- Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital, Cincinnati, Ohio
| | - Claire McCann
- Varian Medical Systems, Siemens Healthineers, Palo Alto, California
| | - Kenneth Russell
- Varian Medical Systems, Siemens Healthineers, Palo Alto, California
| | - Lisa Levine
- Varian Medical Systems, Siemens Healthineers, Palo Alto, California
| | - Ricky A. Sharma
- Varian Medical Systems, Siemens Healthineers, Palo Alto, California
| | - Dee Khuntia
- Varian Medical Systems, Siemens Healthineers, Palo Alto, California
| | - Jeffrey D. Bradley
- Department of Radiation Oncology, Emory University School of Medicine, Atlanta, Georgia
| | - Charles B. Simone
- Department of Radiation Oncology, New York Proton Center, New York, New York
| | - John P. Perentesis
- Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital, Cincinnati, Ohio
| | - John C. Breneman
- Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital, Cincinnati, Ohio
- Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, Ohio
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10
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Ramesh P, Gu W, Ruan D, Sheng K. Dose and dose rate objectives in Bragg peak and shoot-through beam orientation optimization for FLASH proton therapy. Med Phys 2022; 49:7826-7837. [PMID: 36222217 PMCID: PMC9829523 DOI: 10.1002/mp.16009] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/15/2022] [Accepted: 09/15/2022] [Indexed: 01/12/2023] Open
Abstract
PURPOSE The combined use of Bragg peak (BP) and shoot-through (ST) beams has previously been shown to increase the normal tissue volume receiving FLASH dose rates while maintaining dose conformality compared to conventional intensity-modulated proton therapy (IMPT) methods. However, the fixed beam optimization method has not considered the effects of beam orientation on the dose and dose rates. To maximize the proton FLASH effect, here, we incorporate dose rate objectives into our beam orientation optimization framework. METHODS From our previously developed group-sparsity dose objectives, we add upper and lower dose rate terms using a surrogate dose-averaged dose rate definition and solve using the fast-iterative shrinking threshold algorithm. We compare the dosimetry for three head-and-neck cases between four techniques: (1) spread-out BP IMPT (BP), (2) dose rate optimization using BP beams only (BP-DR), (3) dose rate optimization using ST beams only (ST-DR), and (4) dose rate optimization using combined BP and ST (BPST-DR), with the goal of sparing organs at risk without loss of tumor coverage and maintaining high dose rate within a 10 mm region of interest (ROI) surrounding the clinical target volume (CTV). RESULTS For BP, BP-DR, ST-DR, and BPST-DR, CTV homogeneity index and Dmax were found to be on average 0.886, 0.867, 0.687, and 0.936 and 107%, 109%, 135%, and 101% of prescription, respectively. Although ST-DR plans were not able to meet dosimetric standards, BPST-DR was able to match or improve either maximum or mean dose in the right submandibular gland, left and right parotids, constrictors, larynx, and spinal cord compared to BP plans. Volume of ROIs receiving greater than 40 Gy/s ( V γ 0 ) ${V_{\gamma 0}})$ was 51.0%, 91.4%, 95.5%, and 92.1% on average. CONCLUSIONS The dose rate techniques, particularly BPST-DR, were able to significantly increase dose rate without compromising physical dose compared with BP. Our algorithm efficiently selects beams that are optimal for both dose and dose rate.
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Affiliation(s)
- Pavitra Ramesh
- Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Wenbo Gu
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Dan Ruan
- Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Ke Sheng
- Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA 90095, USA
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11
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Rothwell B, Lowe M, Traneus E, Krieger M, Schuemann J. Treatment planning considerations for the development of FLASH proton therapy. Radiother Oncol 2022; 175:222-230. [PMID: 35963397 DOI: 10.1016/j.radonc.2022.08.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/21/2022] [Accepted: 08/01/2022] [Indexed: 10/15/2022]
Abstract
With increasing focus on the translation of the observed FLASH effect into clinical practice, this paper presents treatment planning considerations for its development using proton therapy. Potential requirements to induce a FLASH effect are discussed along with the properties of existing proton therapy delivery systems and the changes in planning and delivery approaches required to satisfy these prerequisites. For the exploration of treatment planning approaches for FLASH, developments in treatment planning systems are needed. Flexibility in adapting to new information will be important in such an evolving area. Variations in definitions, threshold values and assumptions can make it difficult to compare different published studies and to interpret previous studies in the context of new information. Together with the fact that much is left to be understood about the underlying mechanism behind the FLASH effect, a systematic and comprehensive approach to information storage is encouraged. Collecting and retaining more detailed information on planned and realised dose delivery as well as reporting the assumptions made in planning studies creates the potential for research to be revisited and re-evaluated in the light of future improvements in understanding. Forward thinking at the time of study development can help facilitate retrospective analysis. This, we hope, will increase the available evidence and accelerate the translation of the FLASH effect into clinical benefit.
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Affiliation(s)
- Bethany Rothwell
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom.
| | - Matthew Lowe
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom; Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | | | - Miriam Krieger
- Varian Medical Systems Particle Therapy GmbH & Co. KG, Troisdorf, Germany
| | - Jan Schuemann
- Division of Physics, Dept. of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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