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Bobić M, Choulilitsa E, Lee H, Czerska K, Christensen JB, Mayor A, Safai S, Winey BA, Weber DC, Lomax AJ, Paganetti H, Nesteruk KP, Albertini F. Multi-institutional experimental validation of online adaptive proton therapy workflows. Phys Med Biol 2024; 69:165021. [PMID: 39025115 DOI: 10.1088/1361-6560/ad6527] [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: 05/13/2024] [Accepted: 07/18/2024] [Indexed: 07/20/2024]
Abstract
Objective.To experimentally validate two online adaptive proton therapy (APT) workflows using Gafchromic EBT3 films and optically stimulated luminescent dosimeters (OSLDs) in an anthropomorphic head-and-neck phantom.Approach.A three-field proton plan was optimized on the planning CT of the head-and-neck phantom with 2.0 Gy(RBE) per fraction prescribed to the clinical target volume. Four fractions were simulated by varying the internal anatomy of the phantom. Three distinct methods were delivered: daily APT researched by the Paul Scherrer Institute (DAPTPSI), online adaptation researched by the Massachusetts General Hospital (OAMGH), and a non-adaptive (NA) workflow. All methods were implemented and measured at PSI. DAPTPSIperformed full online replanning based on analytical dose calculation, optimizing to the same objectives as the initial treatment plan. OAMGHperformed Monte-Carlo-based online plan adaptation by only changing the fluences of a subset of proton beamlets, mimicking the planned dose distribution. NA delivered the initial plan with a couch-shift correction based on in-room imaging. For all 12 deliveries, two films and two sets of OSLDs were placed at different locations in the phantom.Main results.Both adaptive methods showed improved dosimetric results compared to NA. For film measurements in the presence of anatomical variations, the [min-max] gamma pass rates (3%/3 mm) between measured and clinically approved doses were [91.5%-96.1%], [94.0%-95.8%], and [67.2%-93.1%] for DAPTPSI, OAMGH, and NA, respectively. The OSLDs confirmed the dose calculations in terms of absolute dosimetry. Between the two adaptive workflows, OAMGHshowed improved target coverage, while DAPTPSIshowed improved normal tissue sparing, particularly relevant for the brainstem.Significance.This is the first multi-institutional study to experimentally validate two different concepts with respect to online APT workflows. It highlights their respective dosimetric advantages, particularly in managing interfractional variations in patient anatomy that cannot be addressed by non-adaptive methods, such as internal anatomy changes.
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Affiliation(s)
- Mislav Bobić
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Evangelia Choulilitsa
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Paul Scherrer Institute, Villigen, Switzerland
| | - Hoyeon Lee
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
| | | | | | | | | | - Brian A Winey
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Damien C Weber
- Paul Scherrer Institute, Villigen, Switzerland
- Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland
- Department of Radiation Oncology, University Hospital Bern, University of Bern, Bern, Switzerland
| | - Antony J Lomax
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Paul Scherrer Institute, Villigen, Switzerland
| | - Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Konrad P Nesteruk
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
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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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Domingo Muñoz I, Van Hoey O, Parisi A, Bassler N, Grzanka L, De Saint-Hubert M, Vaniqui A, Olko P, Sądel M, Stolarczyk L, Vestergaard A, Jäkel O, Gardenali Yukihara E, Brage Christensen J. Assessment of fluence- and dose-averaged linear energy transfer with passive luminescence detectors in clinical proton beams. Phys Med Biol 2024; 69:135004. [PMID: 38774985 DOI: 10.1088/1361-6560/ad4e8e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 05/21/2024] [Indexed: 06/22/2024]
Abstract
Objective.This work investigates the use of passive luminescence detectors to determine different types of averaged linear energy transfer (LET-) for the energies relevant to proton therapy. The experimental results are compared to reference values obtained from Monte Carlo simulations.Approach.Optically stimulated luminescence detectors (OSLDs), fluorescent nuclear track detectors (FNTDs), and two different groups of thermoluminescence detectors (TLDs) were irradiated at four different radiation qualities. For each irradiation, the fluence- (LET-f) and dose-averaged LET (LET-d) were determined. For both quantities, two sub-types of averages were calculated, either considering the contributions from primary and secondary protons or from all protons and heavier, charged particles. Both simulated and experimental data were used in combination with a phenomenological model to estimate the relative biological effectiveness (RBE).Main results.All types ofLET-could be assessed with the luminescence detectors. The experimental determination ofLET-fis in agreement with reference data obtained from simulations across all measurement techniques and types of averaging. On the other hand,LET-dcan present challenges as a radiation quality metric to describe the detector response in mixed particle fields. However, excluding secondaries heavier than protons from theLET-dcalculation, as their contribution to the luminescence is suppressed by ionization quenching, leads to equal accuracy betweenLET-fandLET-d. Assessment of RBE through the experimentally determinedLET-dvalues agrees with independently acquired reference values, indicating that the investigated detectors can determineLET-with sufficient accuracy for proton therapy.Significance.OSLDs, TLDs, and FNTDs can be used to determineLET-and RBE in proton therapy. With the capability to determine dose through ionization quenching corrections derived fromLET-, OSLDs and TLDs can simultaneously ascertain dose,LET-, and RBE. This makes passive detectors appealing for measurements in phantoms to facilitate validation of clinical treatment plans or experiments related to proton therapy.
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Affiliation(s)
- Iván Domingo Muñoz
- Department of Physics and Astronomy, University of Heidelberg, Heidelberg, Germany
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | | | - Alessio Parisi
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida, United States of America
| | - Niels Bassler
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Leszek Grzanka
- Institute of Nuclear Physics, Polish Academy of Sciences (IFJ PAN), Kraków, Poland
| | | | - Ana Vaniqui
- Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Paweł Olko
- Institute of Nuclear Physics, Polish Academy of Sciences (IFJ PAN), Kraków, Poland
| | - Michał Sądel
- Institute of Nuclear Physics, Polish Academy of Sciences (IFJ PAN), Kraków, Poland
| | - Liliana Stolarczyk
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Anne Vestergaard
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Oliver Jäkel
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
- Department of Radiation Oncology, Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg University Hospital, Heidelberg, Germany
| | | | - Jeppe Brage Christensen
- Department of Radiation Safety and Security, Paul Scherrer Institute (PSI), Villigen PSI, Switzerland
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Claessens M, Vanreusel V, Gasparini A, Nascimento LDF, Yalvec B, Reniers B, Verellen D. Automated determination of the ion-recombination correction factor (k sat) in ultra-high dose rate electron radiation therapy. Med Phys 2024; 51:4536-4545. [PMID: 38639653 DOI: 10.1002/mp.17085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 03/06/2024] [Accepted: 03/13/2024] [Indexed: 04/20/2024] Open
Abstract
BACKGROUND Plane-parallel ionization chambers are the recommended secondary standard systems for clinical reference dosimetry of electrons. Dosimetry in high dose rate and dose-per-pulse (DPP) is challenging as ionization chambers are subject to ion recombination, especially when dose rate and/or DPP is increased beyond the range of conventional radiotherapy. The lack of universally accepted models for correction of ion recombination in UDHR is still an issue as it is, especially in FLASH-RT research, which is crucial in order to be able to accurately measure the dose for a wide range of dose rates and DPPs. PURPOSE The objective of this study was to show the feasibility of developing an Artificial Intelligence model to predict the ion-recombination factor-ksat for a plane-parallel Advanced Markus ionization chamber for conventional and ultra-high dose rate electron beams based on machine parameters. In addition, the predicted ksat of the AI model was compared with the current applied analytical models for this correction factor. METHODS A total number of 425 measurements was collected with a balanced variety in machine parameter settings. The specific ksat values were determined by dividing the output of the reference dosimeter (optically stimulated luminescence [OSL]) by the output of the AM chamber. Subsequently, a XGBoost regression model was trained, which used the different machine parameters as input features and the corresponding ksat value as output. The prediction accuracy of this regression model was characterized by R2-coefficient of determination, mean absolute error and root mean squared error. In addition, the model was compared with the Two-Voltage (TVA) method and empirical Petersson model for 19 different dose-per-pulse values ranging from conventional to UDHR regimes. The Akiake Information criterion (AIC) was calculated for the three different models. RESULTS The XGBoost regression model reached a R2-score of 0.94 on the independent test set with a MAE of 0.067 and RMSE of 0.106. For the additional 19 random data points, the ksat values predicted by the XGBoost model showed to be in agreement, within the uncertainties, with the ones determined by the Petersson model and better than the TVA method for doses per pulse >3.5 Gy with a maximum deviation from the ground truth of 14.2%, 16.7%, and -36.0%, respectively, for DPP >4 Gy. CONCLUSION The proposed method of using AI for ksat determination displays efficiency. For the investigated DPPs, the ksat values obtained with the XGBoost model were in concurrence with the ones obtained with the current available analytical models within the boundaries of uncertainty, certainly for the DPP characterizing UDHR. But the overall performance of the AI model, taking the number of free parameters into account, lacked efficiency. Future research should optimize the determination of the experimental ksat, and investigate the determination the ksat for DPPs higher than the ones investigated in this study, while also evaluating the prediction of the proposed XGBoost model for UDHR machines of different centers.
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Affiliation(s)
- Michaël Claessens
- Department of Radiation Oncology, Iridium Netwerk, Wilrijk, Antwerp, Belgium
- Centre for Oncological Research (CORE), Integrated Personalized and Precision Oncology Network (IPPON), University of Antwerp, Antwerp, Belgium
| | - Verdi Vanreusel
- Department of Radiation Oncology, Iridium Netwerk, Wilrijk, Antwerp, Belgium
- Centre for Oncological Research (CORE), Integrated Personalized and Precision Oncology Network (IPPON), University of Antwerp, Antwerp, Belgium
- Research in Dosimetric Applications (RDA), SCK CEN, Mol, Antwerp, Belgium
| | - Alessia Gasparini
- Department of Radiation Oncology, Iridium Netwerk, Wilrijk, Antwerp, Belgium
- Centre for Oncological Research (CORE), Integrated Personalized and Precision Oncology Network (IPPON), University of Antwerp, Antwerp, Belgium
| | | | - Burak Yalvec
- NuTeC, CMK, Hasselt University, Hasselt, Belgium
| | | | - Dirk Verellen
- Department of Radiation Oncology, Iridium Netwerk, Wilrijk, Antwerp, Belgium
- Centre for Oncological Research (CORE), Integrated Personalized and Precision Oncology Network (IPPON), University of Antwerp, Antwerp, Belgium
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Liu K, Velasquez B, Schüler E. Technical note: High-dose and ultra-high dose rate (UHDR) evaluation of Al 2 O 3 :C optically stimulated luminescent dosimeter nanoDots and powdered LiF:Mg,Ti thermoluminescent dosimeters for radiation therapy applications. Med Phys 2024; 51:2311-2319. [PMID: 37991111 PMCID: PMC10939935 DOI: 10.1002/mp.16832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 09/11/2023] [Accepted: 10/25/2023] [Indexed: 11/23/2023] Open
Abstract
BACKGROUND Dosimetry in ultra-high dose rate (UHDR) electron beamlines poses a significant challenge owing to the limited usability of standard dosimeters in high dose and high dose-per-pulse (DPP) applications. PURPOSE In this study, Al2 O3 :C nanoDot optically stimulated luminescent dosimeters (OSLDs), single-use powder-based LiF:Mg,Ti thermoluminescent dosimeters (TLDs), and Gafchromic EBT3 film were evaluated at extended dose ranges (up to 40 Gy) in conventional dose rate (CONV) and UHDR beamlines to determine their usability for calibration and dose verification in the setting of FLASH radiation therapy. METHODS OSLDs and TLDs were evaluated against established dose-rate-independent Gafchromic EBT3 film with regard to the potential influence of mean dose rate, instantaneous dose rate, and DPP on signal response. The dosimeters were irradiated at CONV or UHDR conditions on a 9-MeV electron beam. Under UHDR conditions, different settings of pulse repetition frequency (PRF), pulse width (PW), and pulse amplitude were used to characterize the individual dosimeters' response in order to isolate their potential dependencies on dose, dose rate, and DPP. RESULTS The OSLDs, TLDs, and Gafchromic EBT3 film were found to be suitable at a dose range of up to 40 Gy without any indication of saturation in signal. The response of OSLDs and TLDs in UHDR conditions were found to be independent of mean dose rate (up to 1440 Gy/s), instantaneous dose rate (up to 2 MGy/s), and DPP (up to 7 Gy), with uncertainties on par with nominal values established in CONV beamlines (± 4%). In cross-comparing the response of OSLDs, TLDs and Gafchromic film at dose rates of 0.18-245 Gy/s, the coefficient of variation or relative standard deviation in the measured dose between the three dosimeters (inter-dosimeter comparison) was found to be within 2%. CONCLUSIONS We demonstrated the dynamic range of OSLDs, TLDs, and Gafchromic film to be suitable up to 40 Gy, and we developed a protocol that can be used to accurately translate the measured signal in each respective dosimeter to dose. OSLDs and powdered TLDs were shown to be viable for dosimetric measurement in UHDR beamlines, providing dose measurements with accuracies on par with Gafchromic EBT3 film and their concurrent use demonstrating a means for redundant dosimetry in UHDR conditions.
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Affiliation(s)
- Kevin Liu
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, Houston, Texas, USA
| | - Brett Velasquez
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Emil Schüler
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, Houston, Texas, USA
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Motta S, Dal Bello R, Christensen JB, Bossin L, Yukihara EG. Dosimetry of ultra-high dose rate electron beams using thermoluminescence and optically stimulated luminescence detectors. Phys Med Biol 2024; 69:035022. [PMID: 38198704 DOI: 10.1088/1361-6560/ad1cf5] [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: 08/17/2023] [Accepted: 01/10/2024] [Indexed: 01/12/2024]
Abstract
Objective.The aim of this work is to investigate the dose rate dependence of thermoluminescence and optically stimulated luminescence detectors (TLDs and OSLDs) in a wide uniform ultra-high dose rate electron beam and demonstrate the potential use of TLDs and OSLDs to correct the ion recombination in air-filled ionization chambers. This study avoids previously reported complications related to the field size and homogeneity.Approach.Two types of OSLDs (BeO and Al2O3:C) and three types of TLDs (LiF:Mg,Ti, LiF:Mg,Cu,P, CaF2:Tm) were irradiated simultaneously in a uniform 16 MeV electron beam generated by a clinically decommissioned C-Arm LINAC, modified to deliver doses per pulse between 8.3 × 10-4Gy and 1.255 Gy, corresponding to instantaneous dose rates between 2 × 102Gy s-1and 3 × 105Gy s-1. A prototype ultra-thin parallel plate ionization chamber was employed as reference detector.Main results.Reproducible results were achieved both at conventional (standard deviation of the data <2%) and at the highest dose per pulse (standard deviation of the data <4%). No trend in the dose rate response of the TLDs and OSLDs was observed in the investigated dose per pulse range. The Al2O3:C OSLD was found to be the most precise detector, with a standard deviation of the data <2% at all investigated dose rates and dose levels.Significance.The dose rate independence of the investigated TLDs and OSLDs make them good candidates for dosimetry at ultra-high dose rates, at least up to 3 × 105Gy s-1. A dose rate independent method to measure the dose per pulse is proposed, which can be applied to characterize ultra-high dose rate electron beams and correct for ion recombination in ionization chambers.
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Affiliation(s)
- S Motta
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland
- Department of Physics, ETH Zürich, Zürich, Switzerland
| | - R Dal Bello
- Department of Radiation Oncology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - J B Christensen
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - L Bossin
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - E G Yukihara
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland
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Oh K, Gallagher KJ, Hyun M, Schott D, Wisnoskie S, Lei Y, Hendley S, Wong J, Wang S, Graff B, Jenkins C, Rutar F, Ahmed M, McNeur J, Taylor J, Schmidt M, Senadheera L, Smith W, Umstadter D, Lele SM, Dai R, Jianghu (James) D, Yan Y, Su‐min Z. Initial experience with an electron FLASH research extension (FLEX) for the Clinac system. J Appl Clin Med Phys 2024; 25:e14159. [PMID: 37735808 PMCID: PMC10860433 DOI: 10.1002/acm2.14159] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 08/04/2023] [Accepted: 08/21/2023] [Indexed: 09/23/2023] Open
Abstract
PURPOSE Radiotherapy delivered at ultra-high-dose-rates (≥40 Gy/s), that is, FLASH, has the potential to effectively widen the therapeutic window and considerably improve the care of cancer patients. The underlying mechanism of the FLASH effect is not well understood, and commercial systems capable of delivering such dose rates are scarce. The purpose of this study was to perform the initial acceptance and commissioning tests of an electron FLASH research product for preclinical studies. METHODS A linear accelerator (Clinac 23EX) was modified to include a non-clinical FLASH research extension (the Clinac-FLEX system) by Varian, a Siemens Healthineers company (Palo Alto, CA) capable of delivering a 16 MeV electron beam with FLASH and conventional dose rates. The acceptance, commissioning, and dosimetric characterization of the FLEX system was performed using radiochromic film, optically stimulated luminescent dosimeters, and a plane-parallel ionization chamber. A radiation survey was conducted for which the shielding of the pre-existing vault was deemed sufficient. RESULTS The Clinac-FLEX system is capable of delivering a 16 MeV electron FLASH beam of approximately 1 Gy/pulse at isocenter and reached a maximum dose rate >3.8 Gy/pulse near the upper accessory mount on the linac gantry. The percent depth dose curves of the 16 MeV FLASH and conventional modes for the 10 × 10 cm2 applicator agreed within 0.5 mm at a range of 50% of the maximum dose. Their respective profiles agreed well in terms of flatness but deviated for field sizes >10 × 10 cm2 . The output stability of the FLASH system exhibited a dose deviation of <1%. Preliminary cell studies showed that the FLASH dose rate (180 Gy/s) had much less impact on the cell morphology of 76N breast normal cells compared to the non-FLASH dose rate (18 Gy/s), which induced large-size cells. CONCLUSION Our studies characterized the non-clinical Clinac-FLEX system as a viable solution to conduct FLASH research that could substantially increase access to ultra-high-dose-rate capabilities for scientists.
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Affiliation(s)
- Kyuhak Oh
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | | | - Megan Hyun
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | - Diane Schott
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | | | - Yu Lei
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | | | - Jeffrey Wong
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | - Shuo Wang
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | - Brendan Graff
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | | | - Frank Rutar
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | - Md Ahmed
- Varian Medical SystemsPalo AltoCaliforniaUSA
| | | | | | | | | | - Wendy Smith
- Varian Medical SystemsPalo AltoCaliforniaUSA
| | | | | | - Ran Dai
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | | | - Ying Yan
- University of Nebraska Medical CenterOmahaNebraskaUSA
| | - Zhou Su‐min
- University of Nebraska Medical CenterOmahaNebraskaUSA
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Bobić M, Christensen JB, Lee H, Choulilitsa E, Czerska K, Togno M, Safai S, Yukihara EG, Winey BA, Lomax AJ, Paganetti H, Albertini F, Nesteruk KP. Optically stimulated luminescence dosimeters for simultaneous measurement of point dose and dose-weighted LET in an adaptive proton therapy workflow. Front Oncol 2024; 13:1333039. [PMID: 38510267 PMCID: PMC10951997 DOI: 10.3389/fonc.2023.1333039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 12/18/2023] [Indexed: 03/22/2024] Open
Abstract
Purpose To demonstrate the suitability of optically stimulated luminescence detectors (OSLDs) for accurate simultaneous measurement of the absolute point dose and dose-weighted linear energy transfer (LETD) in an anthropomorphic phantom for experimental validation of daily adaptive proton therapy. Methods A clinically realistic intensity-modulated proton therapy (IMPT) treatment plan was created based on a CT of an anthropomorphic head-and-neck phantom made of tissue-equivalent material. The IMPT plan was optimized with three fields to deliver a uniform dose to the target volume covering the OSLDs. Different scenarios representing inter-fractional anatomical changes were created by modifying the phantom. An online adaptive proton therapy workflow was used to recover the daily dose distribution and account for the applied geometry changes. To validate the adaptive workflow, measurements were performed by irradiating Al2O3:C OSLDs inside the phantom. In addition to the measurements, retrospective Monte Carlo simulations were performed to compare the absolute dose and dose-averaged LET (LETD) delivered to the OSLDs. Results The online adaptive proton therapy workflow was shown to recover significant degradation in dose conformity resulting from large anatomical and positioning deviations from the reference plan. The Monte Carlo simulations were in close agreement with the OSLD measurements, with an average relative error of 1.4% for doses and 3.2% for LETD. The use of OSLDs for LET determination allowed for a correction for the ionization quenched response. Conclusion The OSLDs appear to be an excellent detector for simultaneously assessing dose and LET distributions in proton irradiation of an anthropomorphic phantom. The OSLDs can be cut to almost any size and shape, making them ideal for in-phantom measurements to probe the radiation quality and dose in a predefined region of interest. Although we have presented the results obtained in the experimental validation of an adaptive proton therapy workflow, the same approach can be generalized and used for a variety of clinical innovations and workflow developments that require accurate assessment of point dose and/or average LET.
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Affiliation(s)
- Mislav Bobić
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | | | - Hoyeon Lee
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Evangelia Choulilitsa
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Paul Scherrer Institute, Villigen, Switzerland
| | | | | | | | | | - Brian A. Winey
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Antony J. Lomax
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Paul Scherrer Institute, Villigen, Switzerland
| | - Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | | | - Konrad P. Nesteruk
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
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Almeida A, Togno M, Ballesteros-Zebadua P, Franco-Perez J, Geyer R, Schaefer R, Petit B, Grilj V, Meer D, Safai S, Lomax T, Weber DC, Bailat C, Psoroulas S, Vozenin MC. Dosimetric and biologic intercomparison between electron and proton FLASH beams. Radiother Oncol 2024; 190:109953. [PMID: 37839557 DOI: 10.1016/j.radonc.2023.109953] [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: 04/12/2023] [Revised: 10/07/2023] [Accepted: 10/11/2023] [Indexed: 10/17/2023]
Abstract
BACKGROUND AND PURPOSE The FLASH effect has been validated in different preclinical experiments with electrons (eFLASH) and protons (pFLASH) operating at an average dose rate above 40 Gy/s. However, no systematic intercomparison of the FLASH effect produced by eFLASHvs. pFLASH has yet been performed and constitutes the aim of the present study. MATERIALS AND METHODS The electron eRT6/Oriatron/CHUV/5.5 MeV and proton Gantry1/PSI/170 MeV were used to deliver conventional (0.1 Gy/s eCONV and pCONV) and FLASH (≥110 Gy/s eFLASH and pFLASH) dose rates. Protons were delivered in transmission. Dosimetric and biologic intercomparisons were performed using previously validated dosimetric approaches and experimental murine models. RESULTS The difference between the average absorbed dose measured at Gantry 1 with PSI reference dosimeters and with CHUV/IRA dosimeters was -1.9 % (0.1 Gy/s) and + 2.5 % (110 Gy/s). The neurocognitive capacity of eFLASH and pFLASH irradiated mice was indistinguishable from the control, while both eCONV and pCONV irradiated cohorts showed cognitive decrements. Complete tumor response was obtained after an ablative dose of 20 Gy delivered with the two beams at CONV and FLASH dose rates. Tumor rejection upon rechallenge indicates that anti-tumor immunity was activated independently of the beam-type and the dose-rate. CONCLUSION Despite major differences in the temporal microstructure of proton and electron beams, this study shows that dosimetric standards can be established. Normal brain protection and tumor control were produced by the two beams. More specifically, normal brain protection was achieved when a single dose of 10 Gy was delivered in 90 ms or less, suggesting that the most important physical parameter driving the FLASH sparing effect might be the mean dose rate. In addition, a systemic anti-tumor immunological memory response was observed in mice exposed to high ablative dose of electron and proton delivered at CONV and FLASH dose rate.
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Affiliation(s)
- A Almeida
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - M Togno
- Center for Proton Therapy, Paul Scherrer Institute, 5323, Villigen, Switzerland
| | - P Ballesteros-Zebadua
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Instituto Nacional de Neurología y Neurocirugía MVS, Mexico City, Mexico
| | - J Franco-Perez
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Instituto Nacional de Neurología y Neurocirugía MVS, Mexico City, Mexico
| | - R Geyer
- Department of Radiation Oncology, lnselspital, Bern University Hospital, University of Bern, Switzerland
| | - R Schaefer
- Center for Proton Therapy, Paul Scherrer Institute, 5323, Villigen, Switzerland
| | - B Petit
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - V Grilj
- Institute of Radiation Physics (IRA)/CHUV, Lausanne University Hospital, Lausanne, Switzerland
| | - D Meer
- Center for Proton Therapy, Paul Scherrer Institute, 5323, Villigen, Switzerland
| | - S Safai
- Center for Proton Therapy, Paul Scherrer Institute, 5323, Villigen, Switzerland
| | - T Lomax
- Center for Proton Therapy, Paul Scherrer Institute, 5323, Villigen, Switzerland
| | - D C Weber
- Center for Proton Therapy, Paul Scherrer Institute, 5323, Villigen, Switzerland; Department of Radiation Oncology, lnselspital, Bern University Hospital, University of Bern, Switzerland; Department of Radiation Oncology, University Hospital of Zurich, Switzerland
| | - C Bailat
- Institute of Radiation Physics (IRA)/CHUV, Lausanne University Hospital, Lausanne, Switzerland
| | - S Psoroulas
- Center for Proton Therapy, Paul Scherrer Institute, 5323, Villigen, Switzerland
| | - Marie-Catherine Vozenin
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Radiotherapy and Radiobiology sector, Radiation Therapy service, University hospital of Geneva, Geneva, Switzerland.
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10
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Yamaguchi S, Ieko Y, Ariga H, Yoshioka K. Electron beam detection in radiotherapy using a capacitor dosimeter equipped with a silicon photodiode. Med Biol Eng Comput 2023:10.1007/s11517-023-02870-7. [PMID: 37380785 DOI: 10.1007/s11517-023-02870-7] [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: 11/25/2022] [Accepted: 06/16/2023] [Indexed: 06/30/2023]
Abstract
In this study, a newly developed capacitor dosimeter was evaluated using electron beams commonly utilized in radiotherapy. The capacitor dosimeter comprised a silicon photodiode, 0.47-μF capacitor, and dedicated terminal (dock). Before electron beam irradiation, the dosimeter was charged using the dock. The doses were measured without using a cable by reducing the charging voltages using the currents from the photodiode during irradiation. A commercially available parallel-plane-type ionization chamber and solid-water phantom were used for dose calibration with an electron energy of 6 MeV. In addition, the depth doses were measured using a solid-water phantom at electron energies of 6, 9, and 12 MeV. The doses were proportional to the discharging voltages, and the maximum dose difference in the calibrated doses measured using a two-point calibration was approximately 5% in the range of 0.25-1.98 Gy. The depth dependencies at energies of 6, 9, and 12 MeV corresponded to those measured using the ionization chamber.
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Affiliation(s)
- Satoshi Yamaguchi
- Department of Radiology, School of Medicine, Iwate Medical University, 2-1-1, Idaidori, Yahaba, Iwate, 028-3695, Japan.
| | - Yoshiro Ieko
- Department of Radiation Oncology, Iwate Medical University Hospital, Iwate Medical University, 2-1-1, Idaidori, Yahaba, Iwate, 028-3695, Japan
| | - Hisanori Ariga
- Department of Radiation Oncology, Iwate Medical University Hospital, Iwate Medical University, 2-1-1, Idaidori, Yahaba, Iwate, 028-3695, Japan
| | - Kunihiro Yoshioka
- Department of Radiology, School of Medicine, Iwate Medical University, 2-1-1, Idaidori, Yahaba, Iwate, 028-3695, Japan
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11
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Almeida A, Togno M, Ballesteros-Zebadua P, Franco-Perez J, Geyer R, Schaefer R, Petit B, Grilj V, Meer D, Safai S, Lomax T, Weber DC, Bailat C, Psoroulas S, Vozenin MC. Dosimetric and biologic intercomparison between electron and proton FLASH beams. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.20.537497. [PMID: 37131769 PMCID: PMC10153243 DOI: 10.1101/2023.04.20.537497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Background and purpose The FLASH effect has been validated in different preclinical experiments with electrons (eFLASH) and protons (pFLASH) operating at a mean dose rate above 40 Gy/s. However, no systematic intercomparison of the FLASH effect produced by e vs. pFLASH has yet been performed and constitutes the aim of the present study. Materials and methods The electron eRT6/Oriatron/CHUV/5.5 MeV and proton Gantry1/PSI/170 MeV were used to deliver conventional (0.1 Gy/s eCONV and pCONV) and FLASH (≥100 Gy/s eFLASH and pFLASH) irradiation. Protons were delivered in transmission. Dosimetric and biologic intercomparisons were performed with previously validated models. Results Doses measured at Gantry1 were in agreement (± 2.5%) with reference dosimeters calibrated at CHUV/IRA. The neurocognitive capacity of e and pFLASH irradiated mice was indistinguishable from the control while both e and pCONV irradiated cohorts showed cognitive decrements. Complete tumor response was obtained with the two beams and was similar between e and pFLASH vs. e and pCONV. Tumor rejection was similar indicating that T-cell memory response is beam-type and dose-rate independent. Conclusion Despite major differences in the temporal microstructure, this study shows that dosimetric standards can be established. The sparing of brain function and tumor control produced by the two beams were similar, suggesting that the most important physical parameter driving the FLASH effect is the overall time of exposure which should be in the range of hundreds of milliseconds for WBI in mice. In addition, we observed that immunological memory response is similar between electron and proton beams and is independent off the dose rate.
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Affiliation(s)
- A Almeida
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - M Togno
- Center for Proton Therapy, Paul Scherrer Institute, 5323 Villigen PSI, Switzerland
| | - P Ballesteros-Zebadua
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- Instituto Nacional de Neurología y Neurocirugía MVS, Mexico City, Mexico
| | - J Franco-Perez
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- Instituto Nacional de Neurología y Neurocirugía MVS, Mexico City, Mexico
| | - R Geyer
- Department of Radiation Oncology, lnselspital, Bern University Hospital, University of Bern, Switzerland
| | - R Schaefer
- Center for Proton Therapy, Paul Scherrer Institute, 5323 Villigen PSI, Switzerland
| | - B Petit
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - V Grilj
- Institute of Radiation Physics (IRA)/CHUV, Lausanne University Hospital, Lausanne, Switzerland
| | - D Meer
- Center for Proton Therapy, Paul Scherrer Institute, 5323 Villigen PSI, Switzerland
| | - S Safai
- Center for Proton Therapy, Paul Scherrer Institute, 5323 Villigen PSI, Switzerland
| | - T Lomax
- Center for Proton Therapy, Paul Scherrer Institute, 5323 Villigen PSI, Switzerland
| | - D C Weber
- Center for Proton Therapy, Paul Scherrer Institute, 5323 Villigen PSI, Switzerland
- Department of Radiation Oncology, lnselspital, Bern University Hospital, University of Bern, Switzerland
- Department of Radiation Oncology, University Hospital of Zurich, Switzerland
| | - C Bailat
- Institute of Radiation Physics (IRA)/CHUV, Lausanne University Hospital, Lausanne, Switzerland
| | - S Psoroulas
- Center for Proton Therapy, Paul Scherrer Institute, 5323 Villigen PSI, Switzerland
| | - M C Vozenin
- Laboratory of Radiation Oncology/Radiation Oncology Service/Department of Oncology/CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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12
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Bossin L, Plokhikh I, Christensen JB, Gawryluk DJ, Kitagawa Y, Leblans P, Tanabe S, Vandenbroucke D, Yukihara EG. Addressing Current Challenges in OSL Dosimetry Using MgB 4O 7:Ce,Li: State of the Art, Limitations and Avenues of Research. MATERIALS (BASEL, SWITZERLAND) 2023; 16:3051. [PMID: 37109886 PMCID: PMC10142933 DOI: 10.3390/ma16083051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/29/2023] [Accepted: 04/03/2023] [Indexed: 06/19/2023]
Abstract
The objective of this work is to review and assess the potential of MgB4O7:Ce,Li to fill in the gaps where the need for a new material for optically stimulated luminescence (OSL) dosimetry has been identified. We offer a critical assessment of the operational properties of MgB4O7:Ce,Li for OSL dosimetry, as reviewed in the literature and complemented by measurements of thermoluminescence spectroscopy, sensitivity, thermal stability, lifetime of the luminescence emission, dose response at high doses (>1000 Gy), fading and bleachability. Overall, compared with Al2O3:C, for example, MgB4O7:Ce,Li shows a comparable OSL signal intensity following exposure to ionizing radiation, a higher saturation limit (ca 7000 Gy) and a shorter luminescence lifetime (31.5 ns). MgB4O7:Ce,Li is, however, not yet an optimum material for OSL dosimetry, as it exhibits anomalous fading and shallow traps. Further optimization is therefore needed, and possible avenues of investigation encompass gaining a better understanding of the roles of the synthesis route and dopants and of the nature of defects.
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Affiliation(s)
- Lily Bossin
- Department of Radiation Safety and Security, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland (E.G.Y.)
| | - Igor Plokhikh
- Department of Radiation Safety and Security, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland (E.G.Y.)
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Jeppe Brage Christensen
- Department of Radiation Safety and Security, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland (E.G.Y.)
| | - Dariusz Jakub Gawryluk
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Yuuki Kitagawa
- National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan
| | - Paul Leblans
- Radiology Division, Agfa NV, 2640 Mortsel, Belgium
| | - Setsuhisa Tanabe
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | | | - Eduardo Gardenali Yukihara
- Department of Radiation Safety and Security, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland (E.G.Y.)
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13
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Motta S, Christensen JB, Togno M, Schäfer R, Safai S, Lomax AJ, Yukihara EG. Characterization of LiF:Mg,Ti thermoluminescence detectors in low-LET proton beams at ultra-high dose rates. Phys Med Biol 2023; 68. [PMID: 36696696 DOI: 10.1088/1361-6560/acb634] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/25/2023] [Indexed: 01/26/2023]
Abstract
Objective.This work aims at characterizing LiF:Mg,Ti thermoluminescence detectors (TLDs) for dosimetry of a 250 MeV proton beam delivered at ultra-high dose rates (UHDR). Possible dose rate effects in LiF:Mg,Ti, as well as its usability for dosimetry of narrow proton beams are investigated.Approach.LiF:Mg,Ti (TLD-100TMMicrocubes, 1 mm × 1 mm × 1 mm) was packaged in matrices of 5 × 5 detectors. The center of each matrix was irradiated with single-spot low-LET (energy >244 MeV) proton beam in the (1-4500) Gy s-1average dose rates range. A beam reconstruction procedure was applied to the detectors irradiated at the highest dose rate (Gaussian beam sigma <2 mm) to correct for volumetric averaging effects. Reference dosimetry was carried out with a diamond detector and radiochromic films. The delivered number of protons was measured by a Faraday cup, which was employed to normalize the detector responses.Main results.The lateral beam spread obtained from the beam reconstruction agreed with the one derived from the radiochromic film measurements. No dose rates effects were observed in LiF:Mg,Ti for the investigated dose rates within 3% (k= 1). On average, the dose response of the TLDs agreed with the reference detectors within their uncertainties. The largest deviation (-5%) was measured at 4500 Gy s-1.Significance.The dose rate independence of LiF:Mg,Ti TLDs makes them suitable for dosimetry of UHDR proton beams. Additionally, the combination of a matrix of TLDs and the beam reconstruction can be applied to determine the beam profile of narrow proton beams.
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Affiliation(s)
- S Motta
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland.,Department of Physics, ETH Zürich, Zürich, Switzerland
| | - J B Christensen
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - M Togno
- Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - R Schäfer
- Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - S Safai
- Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - A J Lomax
- Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI, Switzerland.,Department of Physics, ETH Zürich, Zürich, Switzerland
| | - E G Yukihara
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland
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14
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Calheiro DS, Meira-Belo LC. Effect of Re-sintering on the morphological and thermoluminescence properties of the ALOX-520 detector. Appl Radiat Isot 2023; 192:110580. [PMID: 36462301 DOI: 10.1016/j.apradiso.2022.110580] [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: 10/10/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 11/27/2022]
Abstract
Significant research is being conducted on new materials suitable for dosimetry in recent decades with particular focus on their luminescent properties. For instance, a new ceramic detector, aluminum oxide 520 (ALOX-520), was developed at CDTN in 2011 using the sol-gel method. The detectors were doped with C, Fe, Mg, Ca, Cr, Ni, and Mo impurities that generated the necessary dosimetric trap levels to enhance the luminescence effects. Consequently, the resultant material was appropriate for the quantification of ionizing radiation fields by both thermally and optically stimulated luminescence techniques. Originally, ALOX 520 was sintered at 2023 K under a highly reducing atmosphere. At the end of this process, it exhibited important dosimetric properties, as already described in existing literature. The objective of this study is to conduct tests at higher temperatures in vacuum to investigate the effect of thermal treatments under these conditions on the structural and dosimetric properties of the material. Accordingly, ALOX-520 was re-sintered at high temperatures and the changes in its physical, morphological, and dosimetric properties were analyzed. ALOX 520T exhibited better dosimetric properties in terms of homogeneity, reproducibility, linearity, and signal fading. Physically, an increase in the detection threshold value of ALOX-520T could be linked to a decrease in the sensitivity of this detector. The energy dependence, the thermal quenching correction, and kinetic studies for ALOX-520T conducted as part of this work are original. However, the obtained results are consistent with those reported in the literature for α-Al2O3 ceramic detectors. XRD and XRF analyses demonstrated that the thermal treatment did not change the crystalline structure or composition of the material. All the results indicate that an appropriate thermal treatment could improve the dosimetric properties of the ALOX-520 detector without causing significant changes in its crystalline structure.
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Affiliation(s)
- D S Calheiro
- Nuclear Technology Development Center, CDTN, 31270-901, Belo Horizonte, MG, Brazil
| | - L C Meira-Belo
- Nuclear Technology Development Center, CDTN, 31270-901, Belo Horizonte, MG, Brazil.
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15
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Buranurak S, Pong-Inwong V, Hanpanich P, Wongwiwatchai J, Ahooja A, Pungkun V. Al2O3:C optically stimulated luminescence dosimetry for evaluation of potential factors contributing to entrance skin doses received by liver cancer patients undergoing Transarterial Chemoembolization. Radiat Phys Chem Oxf Engl 1993 2023. [DOI: 10.1016/j.radphyschem.2022.110570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Togno M, Nesteruk KP, Schäfer R, Psoroulas S, Meer D, Grossmann M, Christensen JB, Yukihara EG, Lomax AJ, Weber DC, Safai S. Ultra-high dose rate dosimetry for pre-clinical experiments with mm-small proton fields. Phys Med 2022; 104:101-111. [PMID: 36395638 DOI: 10.1016/j.ejmp.2022.10.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 10/10/2022] [Accepted: 10/23/2022] [Indexed: 11/15/2022] Open
Abstract
PURPOSE To characterize an experimental setup for ultra-high dose rate (UHDR) proton irradiations, and to address the challenges of dosimetry in millimetre-small pencil proton beams. METHODS At the PSI Gantry 1, high-energy transmission pencil beams can be delivered to biological samples and detectors up to a maximum local dose rate of ∼9000 Gy/s. In the presented setup, a Faraday cup is used to measure the delivered number of protons up to ultra-high dose rates. The response of transmission ion-chambers, as well as of different field detectors, was characterized over a wide range of dose rates using the Faraday cup as reference. RESULTS The reproducibility of the delivered proton charge was better than 1 % in the proposed experimental setup. EBT3 films, Al2O3:C optically stimulated luminescence detectors and a PTW microDiamond were used to validate the predicted dose. Transmission ionization chambers showed significant volume ion-recombination (>30 % in the tested conditions) which can be parametrized as a function of the maximum proton current density. Over the considered range, EBT3 films, inorganic scintillator-based screens and the PTW microDiamond were demonstrated to be dose rate independent within ±3 %, ±1.8 % and ±1 %, respectively. CONCLUSIONS Faraday cups are versatile dosimetry instruments that can be used for dose estimation, field detector characterization and on-line dose verification for pre-clinical experiments in UHDR proton pencil beams. Among the tested detectors, the commercial PTW microDiamond was found to be a suitable option to measure real time the dosimetric properties of narrow pencil proton beams for dose rates up to 2.2 kGy/s.
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Affiliation(s)
- M Togno
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland.
| | - K P Nesteruk
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, USA
| | - R Schäfer
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland
| | - S Psoroulas
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland
| | - D Meer
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland
| | - M Grossmann
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland
| | - J B Christensen
- Department of Radiation Safety and Security, Paul Scherrer Institut, Villigen, Switzerland
| | - E G Yukihara
- Department of Radiation Safety and Security, Paul Scherrer Institut, Villigen, Switzerland
| | - A J Lomax
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland; Department of Physics, ETH Zurich, Zurich, Switzerland
| | - D C Weber
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland; Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland; Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - S Safai
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland
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17
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de Freitas Nascimento L, Leblans P, van der Heyden B, Akselrod M, Goossens J, Correa Rocha LE, Vaniqui A, Verellen D. Characterisation and Quenching Correction for an Al 2O 3:C Optical Fibre Real Time System in Therapeutic Proton, Helium, and Carbon-Charged Beams. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22239178. [PMID: 36501879 DOI: 10.1016/j.sna.2022.113781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 05/24/2023]
Abstract
Real time radioluminescence fibre-based detectors were investigated for application in proton, helium, and carbon therapy dosimetry. The Al2O3:C probes are made of one single crystal (1 mm) and two droplets of micro powder in two sizes (38 μm and 4 μm) mixed with a water-equivalent binder. The fibres were irradiated behind different thicknesses of solid slabs, and the Bragg curves presented a quenching effect attributed to the nonlinear response of the radioluminescence (RL) signal as a function of linear energy transfer (LET). Experimental data and Monte Carlo simulations were utilised to acquire a quenching correction method, adapted from Birks' formulation, to restore the linear dose-response for particle therapy beams. The method for quenching correction was applied and yielded the best results for the '4 μm' optical fibre probe, with an agreement at the Bragg peak of 1.4% (160 MeV), and 1.5% (230 MeV) for proton-charged particles; 2.4% (150 MeV/u) for helium-charged particles and of 4.8% (290 MeV/u) and 2.9% (400 MeV/u) for the carbon-charged particles. The most substantial deviations for the '4 μm' optical fibre probe were found at the falloff regions, with ~3% (protons), ~5% (helium) and 6% (carbon).
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Affiliation(s)
| | | | | | - Mark Akselrod
- Landauer, Stillwater Crystal Growth Division, Stillwater, OK 74074, USA
| | - Jo Goossens
- Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Antwerp, Belgium
- Iridium Netwerk, University of Antwerp, 2610 Antwerp, Belgium
| | - Luis Enrique Correa Rocha
- Department of Economics, Ghent University, 9000 Ghent, Belgium
- Department of Physics and Astronomy, Ghent University, 9000 Ghent, Belgium
| | - Ana Vaniqui
- Belgian Nuclear Research Centre, SCK CEN, 2400 Mol, Belgium
| | - Dirk Verellen
- Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Antwerp, Belgium
- Iridium Netwerk, University of Antwerp, 2610 Antwerp, Belgium
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18
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de Freitas Nascimento L, Leblans P, van der Heyden B, Akselrod M, Goossens J, Correa Rocha LE, Vaniqui A, Verellen D. Characterisation and Quenching Correction for an Al 2O 3:C Optical Fibre Real Time System in Therapeutic Proton, Helium, and Carbon-Charged Beams. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22239178. [PMID: 36501879 PMCID: PMC9737660 DOI: 10.3390/s22239178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 05/08/2023]
Abstract
Real time radioluminescence fibre-based detectors were investigated for application in proton, helium, and carbon therapy dosimetry. The Al2O3:C probes are made of one single crystal (1 mm) and two droplets of micro powder in two sizes (38 μm and 4 μm) mixed with a water-equivalent binder. The fibres were irradiated behind different thicknesses of solid slabs, and the Bragg curves presented a quenching effect attributed to the nonlinear response of the radioluminescence (RL) signal as a function of linear energy transfer (LET). Experimental data and Monte Carlo simulations were utilised to acquire a quenching correction method, adapted from Birks' formulation, to restore the linear dose-response for particle therapy beams. The method for quenching correction was applied and yielded the best results for the '4 μm' optical fibre probe, with an agreement at the Bragg peak of 1.4% (160 MeV), and 1.5% (230 MeV) for proton-charged particles; 2.4% (150 MeV/u) for helium-charged particles and of 4.8% (290 MeV/u) and 2.9% (400 MeV/u) for the carbon-charged particles. The most substantial deviations for the '4 μm' optical fibre probe were found at the falloff regions, with ~3% (protons), ~5% (helium) and 6% (carbon).
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Affiliation(s)
| | | | | | - Mark Akselrod
- Landauer, Stillwater Crystal Growth Division, Stillwater, OK 74074, USA
| | - Jo Goossens
- Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Antwerp, Belgium
- Iridium Netwerk, University of Antwerp, 2610 Antwerp, Belgium
| | - Luis Enrique Correa Rocha
- Department of Economics, Ghent University, 9000 Ghent, Belgium
- Department of Physics and Astronomy, Ghent University, 9000 Ghent, Belgium
| | - Ana Vaniqui
- Belgian Nuclear Research Centre, SCK CEN, 2400 Mol, Belgium
| | - Dirk Verellen
- Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Antwerp, Belgium
- Iridium Netwerk, University of Antwerp, 2610 Antwerp, Belgium
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19
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Yukihara EG, Bos AJ, Bilski P, McKeever SW. The quest for new thermoluminescence and optically stimulated luminescence materials: Needs, strategies and pitfalls. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2022.106846] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Comparing radiolytic production of H 2O 2 and development of Zebrafish embryos after ultra high dose rate exposure with electron and transmission proton beams. Radiother Oncol 2022; 175:197-202. [PMID: 35868604 DOI: 10.1016/j.radonc.2022.07.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/30/2022] [Accepted: 07/13/2022] [Indexed: 11/21/2022]
Abstract
The physico-chemical and biological response to conventional and UHDR electron and proton beams was investigated, along with conventional photons. The temporal structure and nature of the beam affected both, with electron beam at ≥1400 Gy/s and proton beam at 0.1 and 1260 Gy/s found to be isoefficient at sparing zebrafish embryos.
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21
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Christensen JB, Togno M, Bossin L, Pakari OV, Safai S, Yukihara EG. Improved simultaneous LET and dose measurements in proton therapy. Sci Rep 2022; 12:8262. [PMID: 35585205 PMCID: PMC9117334 DOI: 10.1038/s41598-022-10575-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 04/11/2022] [Indexed: 11/23/2022] Open
Abstract
The objective of this study was to improve the precision of linear energy transfer (LET) measurements using \documentclass[12pt]{minimal}
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\begin{document}$$\text {Al}_2\text {O}_3\text {:C}$$\end{document}Al2O3:C optically stimulated luminescence detectors (OSLDs) in proton beams, and, with that, improve OSL dosimetry by correcting the readout for the LET-dependent ionization quenching. The OSLDs were irradiated in spot-scanning proton beams at different doses for fluence-averaged LET values in the (0.4–6.5) \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {keV}\, \upmu \hbox {m}^{-1}$$\end{document}keVμm-1 range (in water). A commercial automated OSL reader with a built-in beta source was used for the readouts, which enabled a reference irradiation and readout of each OSLD to establish individual corrections. Pulsed OSL was used to separately measure the blue (F-center) and UV (\documentclass[12pt]{minimal}
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\begin{document}$$F^+$$\end{document}F+-center) emission bands of \documentclass[12pt]{minimal}
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\begin{document}$$\text {Al}_2\text {O}_3\text {:C}$$\end{document}Al2O3:C and the ratio between them (UV/blue signal) was used for the LET measurements. The average deviation between the simulated and measured LET values along the central beam axis amounts to 5.5% if both the dose and LET are varied, but the average deviation is reduced to 3.5% if the OSLDs are irradiated with the same doses. With the measurement procedure and automated equipment used here, the variation in the signals used for LET estimates and quenching-corrections is reduced from 0.9 to 0.6%. The quenching-corrected OSLD doses are in agreement with ionization chamber measurements within the uncertainties. The automated OSLD corrections are demonstrated to improve the LET estimates and the ionization quenching-corrections in proton dosimetry for a clinically relevant energy range up to 230 MeV. It is also for the first time demonstrated how the LET can be estimated for different doses.
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Affiliation(s)
- Jeppe Brage Christensen
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland.
| | - Michele Togno
- Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - Lily Bossin
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - Oskari Ville Pakari
- Department of Radiation Safety and Security, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - Sairos Safai
- Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI, Switzerland
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22
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Optically stimulated luminescence in state-of-the-art LYSO:Ce scintillators enables high spatial resolution 3D dose imaging. Sci Rep 2022; 12:8301. [PMID: 35585168 PMCID: PMC9117671 DOI: 10.1038/s41598-022-12255-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 05/06/2022] [Indexed: 11/08/2022] Open
Abstract
In this contribution, we study the optically stimulated luminescence (OSL) exhibited by commercial \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Lu}_{(2-x)}\hbox {Y}_x\hbox {SiO}_5$$\end{document}Lu(2-x)YxSiO5:Ce crystals. This photon emission mechanism, complementary to scintillation, can trap a fraction of radiation energy deposited in the material and provides sufficient signal to develop a novel post-irradiation 3D dose readout. We characterize the OSL emission through spectrally and temporally resolved measurements and monitor the dose linearity response over a broad range. The measurements show that the \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Ce}^{3+}$$\end{document}Ce3+ centers responsible for scintillation also function as recombination centers for the OSL mechanism. The capture to OSL-active traps competes with scintillation originating from the direct non-radiative energy transfer to the luminescent centers. An OSL response on the order of 100 ph/MeV is estimated. We demonstrate the imaging capabilities provided by such an OSL photon yield using a proof-of-concept optical readout method. A 0.1 \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {mm}^3$$\end{document}mm3 spatial resolution for doses as low as 0.5 Gy is projected using a cubic crystal to image volumetric dose profiles. While OSL degrades the intrinsic scintillating performance by reducing the number of scintillation photons emitted following the passage of ionizing radiation, it can encode highly resolved spatial information of the interaction point of the particle. This feature combines ionizing radiation spectroscopy and 3D reusable dose imaging in a single material.
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23
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Yukihara E, Christensen J, Togno M. Demonstration of an optically stimulated luminescence (OSL) material with reduced quenching for proton therapy dosimetry: MgB4O7:Ce,Li. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2022.106721] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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24
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Nesteruk KP, Togno M, Grossmann M, Lomax AJ, Weber DC, Schippers JM, Safai S, Meer D, Psoroulas S. Commissioning of a clinical pencil beam scanning proton therapy unit for ultra-high dose rates (FLASH). Med Phys 2021; 48:4017-4026. [PMID: 33963576 DOI: 10.1002/mp.14933] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 04/04/2021] [Accepted: 04/27/2021] [Indexed: 12/26/2022] Open
Abstract
PURPOSE The purpose of this work was to provide a flexible platform for FLASH research with protons by adapting a former clinical pencil beam scanning gantry to irradiations with ultra-high dose rates. METHODS PSI Gantry 1 treated patients until December 2018. We optimized the beamline parameters to transport the 250 MeV beam extracted from the PSI COMET accelerator to the treatment room, maximizing the transmission of beam intensity to the sample. We characterized a dose monitor on the gantry to ensure good control of the dose, delivered in spot-scanning mode. We characterized the beam for different dose rates and field sizes for transmission irradiations. We explored scanning possibilities in order to enable conformal irradiations or transmission irradiations of large targets (with transverse scanning). RESULTS We achieved a transmission of 86% from the cyclotron to the treatment room. We reached a peak dose rate of 9000 Gy/s at 3 mm water equivalent depth, along the central axis of a single pencil beam. Field sizes of up to 5 × 5 mm2 were achieved for single-spot FLASH irradiations. Fast transverse scanning allowed to cover a field of 16 × 1.2 cm2 . With the use of a nozzle-mounted range shifter, we are able to span depths in water ranging from 19.6 to 37.9 cm. Various dose levels were delivered with precision within less than 1%. CONCLUSIONS We have realized a proton FLASH irradiation setup able to investigate continuously a wide dose rate spectrum, from 1 to 9000 Gy/s in single-spot irradiation as well as in the pencil beam scanning mode. As such, we have developed a versatile test bench for FLASH research.
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Affiliation(s)
- Konrad P Nesteruk
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
| | - Michele Togno
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
| | - Martin Grossmann
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
| | - Anthony J Lomax
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland.,Department of Physics, ETH Zurich, Zurich, Switzerland
| | - Damien C Weber
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland.,Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland.,Department of Radiation Oncology, University Hospital Bern, Bern, Switzerland
| | - Jacobus M Schippers
- Division of Large Research Facilities, Paul Scherrer Institute, Villigen, Switzerland
| | - Sairos Safai
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
| | - David Meer
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
| | - Serena Psoroulas
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
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25
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FLASH Irradiation with Proton Beams: Beam Characteristics and Their Implications for Beam Diagnostics. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11052170] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
FLASH irradiations use dose-rates orders of magnitude higher than commonly used in patient treatments. Such irradiations have shown interesting normal tissue sparing in cell and animal experiments, and, as such, their potential application to clinical practice is being investigated. Clinical accelerators used in proton therapy facilities can potentially provide FLASH beams; therefore, the topic is of high interest in this field. However, a clear FLASH effect has so far been observed in presence of high dose rates (>40 Gy/s), high delivered dose (tens of Gy), and very short irradiation times (<300 ms). Fulfilling these requirements poses a serious challenge to the beam diagnostics system of clinical facilities. We will review the status and proposed solutions, from the point of view of the beam definitions for FLASH and their implications for beam diagnostics. We will devote particular attention to the topics of beam monitoring and control, as well as absolute dose measurements, since finding viable solutions in these two aspects will be of utmost importance to guarantee that the technique can be adopted quickly and safely in clinical practice.
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