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Saki M, Grewal H, Artz M, Willoughby TR, Park J, Brooks E, Getman N, Senterfitt A, Johnson P. Navigating Complexities: Leadless Pacemaker Management in Proton Therapy for a Pacemaker-Dependent Bilateral Breast Cancer Patient. Int J Part Ther 2024; 13:100112. [PMID: 39105198 PMCID: PMC11298889 DOI: 10.1016/j.ijpt.2024.100112] [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: 02/01/2024] [Revised: 06/10/2024] [Accepted: 06/26/2024] [Indexed: 08/07/2024] Open
Abstract
This case study explores the strategic decision-making and safety considerations in managing a unique scenario where a pacemaker dependent patient, requiring adjuvant radiotherapy for bilateral breast cancer. The conventional pacemaker was located entirely within the treatment target, without the option for transposition because of the bilateral chest treatment, resulting in significant risk of malfunction caused by exposing it to the full prescribed dose. Consequently, the decision was made to replace the conventional pacemaker with a leadless device Micra implanted directly into the heart to mitigate direct device radiation and potential adverse effects of proton therapy on the cardiac device. Following Micra implantation, the patient underwent the proton treatment without complications or serious device malfunctions. This study explores solutions to address the challenges posed by within-the-field cardiac devices and highlights the use of pencil beam proton therapy for individuals with leadless cardiac devices while acknowledging the potential for neutron production and the associated risk of single-event upsets (SEU) in cardiac implantable electronic devices (CIEDs). The findings underscore the significance of strategic decision-making, risk assessment, and continuous monitoring for successful outcomes, particularly in the context of proton therapy for patients with advanced cardiac considerations.
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Affiliation(s)
- Mohammad Saki
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
| | - Hardev Grewal
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
| | - Mark Artz
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
| | - Twyla R. Willoughby
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
| | - Jiyeon Park
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
| | - Eric Brooks
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
| | - Nataly Getman
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
| | - Abby Senterfitt
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
| | - Perry Johnson
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
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Chen D, Motlagh SAO, Stappen FV, Labarbe R, Bell B, Kim M, Teo BKK, Dong L, Zou W, Diffenderfer ES. Secondary neutron dosimetry for conformal FLASH proton therapy. Med Phys 2024; 51:5081-5093. [PMID: 38597815 DOI: 10.1002/mp.17050] [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: 10/31/2023] [Revised: 03/12/2024] [Accepted: 03/13/2024] [Indexed: 04/11/2024] Open
Abstract
BACKGROUND Cyclotron-based proton therapy systems utilize the highest proton energies to achieve an ultra-high dose rate (UHDR) for FLASH radiotherapy. The deep-penetrating range associated with this high energy can be modulated by inserting a uniform plate of proton-stopping material, known as a range shifter, in the beam path at the nozzle to bring the Bragg peak within the target while ensuring high proton transport efficiency for UHDR. Aluminum has been recently proposed as a range shifter material mainly due to its high compactness and its mechanical properties. A possible drawback lies in the fact that aluminum has a larger cross-section of producing secondary neutrons compared to conventional plastic range shifters. Accordingly, an increase in secondary neutron contamination was expected during the delivery of range-modulated FLASH proton therapy, potentially heightening neutron-induced carcinogenic risks to the patient. PURPOSE We conducted neutron dosimetry using simulations and measurements to evaluate excess dose due to neutron exposure during UHDR proton irradiation with aluminum range shifters compared to plastic range shifters. METHODS Monte Carlo simulations in TOPAS were performed to investigate the secondary neutron production characteristics with aluminum range shifter during 225 MeV single-spot proton irradiation. The computational results were validated against measurements with a pair of ionization chambers in an out-of-field region ( ≤ $\le$ 30 cm) and with a Proton Recoil Scintillator-Los Alamos rem meter in a far-out-of-field region (0.5-2.5 m). The assessments were repeated with solid water slabs as a surrogate for the conventional range shifter material to evaluate the impact of aluminum on neutron yield. The results were compared with the International Electrotechnical Commission (IEC) standards to evaluate the clinical acceptance of the secondary neutron yield. RESULTS For a range modulation up to 26 cm in water, the maximum simulated and measured values of out-of-field secondary neutron dose equivalent per therapeutic dose with aluminum range shifter were found to be( 0.57 ± 0.02 ) mSv/Gy $(0.57\pm 0.02)\ \text{mSv/Gy}$ and( 0.46 ± 0.04 ) mSv/Gy $(0.46\pm 0.04)\ \text{mSv/Gy}$ , respectively, overall higher than the solid water cases (simulation:( 0.332 ± 0.003 ) mSv/Gy $(0.332\pm 0.003)\ \text{mSv/Gy}$ ; measurement:( 0.33 ± 0.03 ) mSv/Gy $(0.33\pm 0.03)\ \text{mSv/Gy}$ ). The maximum far out-of-field secondary neutron dose equivalent was found to be (8.8 ± 0.5 $8.8 \pm 0.5$ ) μ Sv / Gy $\umu {\rm Sv/Gy}$ and (1.62 ± 0.02 $1.62 \pm 0.02$ ) μ Sv / Gy $\umu {\rm Sv/Gy}$ for the simulations and rem meter measurements, respectively, also higher than the solid water counterparts (simulation: (3.3 ± 0.3 $3.3 \pm 0.3$ ) μ Sv / Gy $\umu {\rm Sv/Gy}$ ; measurement: (0.63 ± 0.03 $0.63 \pm 0.03$ ) μ Sv / Gy $\umu {\rm Sv/Gy}$ ). CONCLUSIONS We conducted simulations and measurements of secondary neutron production under proton irradiation at FLASH energy with range shifters. We found that the secondary neutron yield increased when using aluminum range shifters compared to conventional materials while remaining well below the non-primary radiation limit constrained by the IEC regulations.
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Affiliation(s)
- Dixin Chen
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | - Rudi Labarbe
- Ion Beam Applications S.A. (IBA), Louvain-la-Neuve, Belgium
| | - Beryl Bell
- Ion Beam Applications S.A. (IBA), Louvain-la-Neuve, Belgium
| | - Michele Kim
- 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
| | - Wei Zou
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Wulff J, Paul A, Bäcker CM, Baumann KS, Esser JN, Koska B, Timmermann B, Verbeek NG, Bäumer C. Consistency of Faraday cup and ionization chamber dosimetry of proton fields and the role of nuclear interactions. Med Phys 2024; 51:2277-2292. [PMID: 37991110 DOI: 10.1002/mp.16819] [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: 01/13/2023] [Revised: 09/21/2023] [Accepted: 09/28/2023] [Indexed: 11/23/2023] Open
Abstract
BACKGROUND A Faraday cup (FC) facilitates a quite clean measurement of the proton fluence emerging from clinical spot-scanning nozzles with narrow pencil-beams. The utilization of FCs appears to be an attractive option for high dose rate delivery modes and the source models of Monte-Carlo (MC) dose engines. However, previous studies revealed discrepancies of 3%-6% between reference dosimetry with ionization chambers (ICs) and FC-based dosimetry. This has prevented the widespread use of FCs for dosimetry in proton therapy. PURPOSE The current study aims at bridging the gap between FC dosimetry and IC dosimetry of proton fields delivered with spot-scanning treatment heads. Particularly, a novel method to evaluate FC measurements is introduced. METHODS A consistency check is formulated, which makes use of the energy balance and the reciprocity theorem. The measurement data comprise central-axis depth distributions of the absorbed dose of quasi-monochromatic fields with a width of about 28.5 cm and FC measurements of the reciprocal fields with a single spot. These data are complemented by a look-up of energy-range tables, the average Q-value of transmutations, and the escape energy carried away by neutrons and photons. The latter data are computed by MC simulations, which in turn are validated with measurements of the distal dose tail and neutron out-of-field doses. For comparison, the conventional approach of FC evaluation is performed, which computes absorbed dose from the product of fluence and stopping power. The results from the FC measurements are compared with the standard dosimetry protocols and improved reference dosimetry methods. RESULTS The deviation between the conventional FC-based dosimetry and the IC-based one according to standard dosimetry protocols was -4.7 ( ± $\pm$ 3.3)% for a 100 MeV field and -3.6 ( ± $\pm$ 3.5)% for 200 MeV, thereby agreeing within the reported uncertainties. The deviations could be reduced to -4.0 ( ± $\pm$ 2.9)% and -3.0 ( ± $\pm$ 3.1)% by adopting state-of-the-art reference dosimetry methods. The alternative approach using the energy balance gave deviations of only -1.9% (100 MeV) and -2.6% (200 MeV) using state-of-the-art dosimetry. The standard uncertainty of this novel approach was estimated to be about 2%. CONCLUSIONS An alternative concept has been established to determine the absorbed dose of monoenergetic proton fields with an FC. It eliminates the strong dependence of the conventional FC-based approach on the MC simulation of the stopping-power and of the secondary ions, which according to the study at hand is the major contributor to the underestimation of the absorbed dose. Some contributions to the uncertainty of the novel approach could potentially be reduced in future studies. This would allow for accurate consistency tests of conventional dosimetry procedures.
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Affiliation(s)
- Jörg Wulff
- West German Proton Therapy Centre Essen, Essen, Germany
- University Hospital Essen, Essen, Germany
- West German Cancer Center (WTZ), Essen, Germany
| | - Anne Paul
- West German Proton Therapy Centre Essen, Essen, Germany
- University Hospital Essen, Essen, Germany
- West German Cancer Center (WTZ), Essen, Germany
- Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Claus Maximilian Bäcker
- West German Proton Therapy Centre Essen, Essen, Germany
- University Hospital Essen, Essen, Germany
- West German Cancer Center (WTZ), Essen, Germany
| | - Kilian-Simon Baumann
- Department of Radiotherapy and Radiation Oncology, Marburg University Hospital, Marburg, Germany
- Marburg Ion-Beam Therapy Center (MIT), Marburg, Germany
- University of Applied Sciences, Institute of Medical Physics and Radiation Protection, Giessen, Germany
| | - Johannes Niklas Esser
- West German Proton Therapy Centre Essen, Essen, Germany
- University Hospital Essen, Essen, Germany
- West German Cancer Center (WTZ), Essen, Germany
| | - Benjamin Koska
- West German Proton Therapy Centre Essen, Essen, Germany
- University Hospital Essen, Essen, Germany
- West German Cancer Center (WTZ), Essen, Germany
| | - Beate Timmermann
- West German Proton Therapy Centre Essen, Essen, Germany
- University Hospital Essen, Essen, Germany
- West German Cancer Center (WTZ), Essen, Germany
- Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- German Cancer Consortium (DKTK), Essen, Germany
- Department of Particle Therapy, University Hospital Essen, Essen, Germany
| | - Nico Gerd Verbeek
- West German Proton Therapy Centre Essen, Essen, Germany
- University Hospital Essen, Essen, Germany
- West German Cancer Center (WTZ), Essen, Germany
| | - Christian Bäumer
- West German Proton Therapy Centre Essen, Essen, Germany
- University Hospital Essen, Essen, Germany
- West German Cancer Center (WTZ), Essen, Germany
- German Cancer Consortium (DKTK), Essen, Germany
- Department of Physics, Technische Universität Dortmund, Dortmund, Germany
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Tjelta J, Ytre-Hauge K, Lyngholm E, Handeland A, Henjum H, Stokkevåg C. Dose exposure to an adult present in the treatment room during pediatric pencil beam scanning proton therapy. Acta Oncol 2023; 62:1531-1535. [PMID: 37676843 DOI: 10.1080/0284186x.2023.2254924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 08/29/2023] [Indexed: 09/09/2023]
Affiliation(s)
- Johannes Tjelta
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | | | - Erlend Lyngholm
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - Andreas Handeland
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - Helge Henjum
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - Camilla Stokkevåg
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
- Department of Physics and Technology, University of Bergen, Bergen, Norway
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Mirzaei M, Rowshanfarzad P, Gill S, Ebert MA, Dass J. Risk of cardiac implantable device malfunction in cancer patients receiving proton therapy: an overview. Front Oncol 2023; 13:1181450. [PMID: 37469405 PMCID: PMC10352826 DOI: 10.3389/fonc.2023.1181450] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 06/12/2023] [Indexed: 07/21/2023] Open
Abstract
Age is a risk factor for both cardiovascular disease and cancer, and as such radiation oncologists frequently see a number of patients with cardiac implantable electronic devices (CIEDs) receiving proton therapy (PT). CIED malfunctions induced by PT are nonnegligible and can occur in both passive scattering and pencil beam scanning modes. In the absence of an evidence-based protocol, the authors emphasise that this patient cohort should be managed differently to electron- and photon- external beam radiation therapy (EBRT) patients due to distinct properties of proton beams. Given the lack of a PT-specific guideline for managing this cohort and limited studies on this important topic; the process was initiated by evaluating all PT-related CIED malfunctions to provide a baseline for future reporting and research. In this review, different modes of PT and their interactions with a variety of CIEDs and pacing leads are discussed. Effects of PT on CIEDs were classified into a variety of hardware and software malfunctions. Apart from secondary neutrons, cumulative radiation dose, dose rate, CIED model/manufacturer, distance from CIED to proton field, and materials used in CIEDs/pacing leads were all evaluated to determine the probability of malfunctions. The importance of proton beam arrangements is highlighted in this study. Manufacturers should specify recommended dose limits for patients undergoing PT. The establishment of an international multidisciplinary team dedicated to CIED-bearing patients receiving PT may be beneficial.
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Affiliation(s)
- Milad Mirzaei
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
- Department of Medical Imaging and Radiation Sciences, School of Biomedical Sciences, Monash University, Clayton, VIC, Australia
| | - Pejman Rowshanfarzad
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, Australia
| | - Suki Gill
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, Australia
| | - Martin A. Ebert
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, Australia
| | - Joshua Dass
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
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Tawonwong T, Suriyapee S, Dachviriyakij T, Pungkun V, Ruangchan S, Sanghangthum T. Measurement of Ambient Dose Equivalent in Compact Proton Therapy using In-house Neutron Moderator-based Poly Allyl Diglycol Carbonate. J Med Phys 2023; 48:243-247. [PMID: 37969145 PMCID: PMC10642591 DOI: 10.4103/jmp.jmp_35_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: 03/14/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 11/17/2023] Open
Abstract
Purpose The high-energy proton produces the unwanted dose contribution from the secondary neutron. The main purpose of this study is to report the validation results of in-house neutron moderator based on poly allyl diglycol carbonate (CR-39) detector, Chulalongkorn University Neutron Moderator (CUMOD) through the ambient dose equivalent, H*(10) measurement. Materials and Methods The Particle and Heavy Ion Transport code System (PHITS) Monte Carlo code was used to simulate the neutron response function. The CUMOD was calibrated with 241AmBe source calibrator in the range of 100-1000 μSv. The variation of neutron fields was generated employing different proton treatment plans covering most of the clinical scenarios. The ambient dose equivalents, H*(10), evaluated employing CUMOD were compared to those obtained with WENDI-II dosimeter. Results The linear relationship between CUMOD and WENDI-II responses showed an R2 value close to 1. The H*(10) per Gy delivered dose was in the range of 22-105 μSv for a 10 cm × 10 cm field. Conclusion The in-house CUMOD neutron moderator can expand the neutron detection dose range of CR-39 detector for ambient dose equivalent. The advantage of CUMODs is its capability to evaluate H*(10) in various positions simultaneously.
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Affiliation(s)
- Tanawat Tawonwong
- Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Her Royal Highness Princess Maha Chakri Sirindhorn Proton Center, Bangkok, Thailand
- Department of Radiology, Division of Radiation Oncology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
| | - Sivalee Suriyapee
- Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Department of Radiology, Division of Radiation Oncology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Tanapol Dachviriyakij
- Nuclear and Radiation Metrology Section, Regulatory Support Division, Office of Atoms for Peace, Bangkok, Thailand
| | - Vithit Pungkun
- Nuclear and Radiation Metrology Section, Regulatory Support Division, Office of Atoms for Peace, Bangkok, Thailand
| | - Sirinya Ruangchan
- Her Royal Highness Princess Maha Chakri Sirindhorn Proton Center, Bangkok, Thailand
- Department of Radiology, Division of Radiation Oncology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
| | - Taweap Sanghangthum
- Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Her Royal Highness Princess Maha Chakri Sirindhorn Proton Center, Bangkok, Thailand
- Department of Radiology, Division of Radiation Oncology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
- Department of Radiology, Division of Radiation Oncology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
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Griffin KT, Yeom YS, Mille MM, Lee C, Jung JW, Hertel NE, Lee C. Comparison of out-of-field normal tissue dose estimates for pencil beam scanning proton therapy: MCNP6, PHITS, and TOPAS. Biomed Phys Eng Express 2022; 9:10.1088/2057-1976/acaab1. [PMID: 36562506 PMCID: PMC10772933 DOI: 10.1088/2057-1976/acaab1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 12/12/2022] [Indexed: 12/14/2022]
Abstract
Monte Carlo (MC) methods are considered the gold-standard approach to dose estimation for normal tissues outside the treatment field (out-of-field) in proton therapy. However, the physics of secondary particle production from high-energy protons are uncertain, particularly for secondary neutrons, due to challenges in performing accurate measurements. Instead, various physics models have been developed over the years to reenact these high-energy interactions based on theory. It should thus be acknowledged that MC users must currently accept some unknown uncertainties in out-of-field dose estimates. In the present study, we compared three MC codes (MCNP6, PHITS, and TOPAS) and their available physics models to investigate the variation in out-of-field normal tissue dosimetry for pencil beam scanning proton therapy patients. Total yield and double-differential (energy and angle) production of two major secondary particles, neutrons and gammas, were determined through irradiation of a water phantom at six proton energies (80, 90, 100, 110, 150, and 200 MeV). Out-of-field normal tissue doses were estimated for intracranial irradiations of 1-, 5-, and 15-year-old patients using whole-body computational phantoms. Notably, the total dose estimates for each out-of-field organ varied by approximately 25% across the three codes, independent of its distance from the treatment volume. Dose discrepancies amongst the codes were linked to the utilized physics model, which impacts the characteristics of the secondary radiation field. Using developer-recommended physics, TOPAS produced both the highest neutron and gamma doses to all out-of-field organs from all examined conditions; this was linked to its highest yields of secondary particles and second hardest energy spectra. Subsequent results when using other physics models found reduced yields and energies, resulting in lower dose estimates. Neutron dose estimates were the most impacted by physics model choice, and thus the variation in out-of-field dose estimates may be even larger than 25% when considering biological effectiveness.
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Affiliation(s)
- Keith T. Griffin
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, USA
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Yeon Soo Yeom
- Department of Radiation Convergence Engineering, Yonsei University, Wonju, South Korea
| | - Matthew M. Mille
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, USA
| | - Choonik Lee
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Jae Won Jung
- Department of Physics, East Carolina University, Greenville, NC, USA
| | - Nolan E. Hertel
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Choonsik Lee
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, USA
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Van Hoey O, Stolarczyk L, Lillhök J, Eliasson L, Mojzeszek N, Liszka M, Alkhiat A, Mares V, Trompier F, Trinkl S, Martínez-Rovira I, Romero-Expósito M, Domingo C, Ploc O, Harrison R, Olko P. Simulation and experimental verification of ambient neutron doses in a pencil beam scanning proton therapy room as a function of treatment plan parameters. Front Oncol 2022; 12:903537. [PMID: 36158693 PMCID: PMC9494550 DOI: 10.3389/fonc.2022.903537] [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: 03/24/2022] [Accepted: 07/07/2022] [Indexed: 11/23/2022] Open
Abstract
Out-of-field patient doses in proton therapy are dominated by neutrons. Currently, they are not taken into account by treatment planning systems. There is an increasing need to include out-of-field doses in the dose calculation, especially when treating children, pregnant patients, and patients with implants. In response to this demand, this work presents the first steps towards a tool for the prediction of out-of-field neutron doses in pencil beam scanning proton therapy facilities. As a first step, a general Monte Carlo radiation transport model for simulation of out-of-field neutron doses was set up and successfully verified by comparison of simulated and measured ambient neutron dose equivalent and neutron fluence energy spectra around a solid water phantom irradiated with a variation of different treatment plan parameters. Simulations with the verified model enabled a detailed study of the variation of the neutron ambient dose equivalent with field size, range, modulation width, use of a range shifter, and position inside the treatment room. For future work, it is planned to use this verified model to simulate out-of-field neutron doses inside the phantom and to verify the simulation results by comparison with previous in-phantom measurement campaigns. Eventually, these verified simulations will be used to build a library and a corresponding tool to allow assessment of out-of-field neutron doses at pencil beam scanning proton therapy facilities.
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Affiliation(s)
- Olivier Van Hoey
- Belgian Nuclear Research Center (SCK CEN), Institute for Environment, Health and Safety (EHS), Mol, Belgium
- *Correspondence: Olivier Van Hoey,
| | - Liliana Stolarczyk
- Danish Centre for Particle Therapy, Aarhus University Hospital (AUH), Aarhus, Denmark
- Institute of Nuclear Physics, Polish Academy of Sciences, (IFJ PAN), Krakow, Poland
- The Skandion Clinic, Uppsala, Sweden
| | - Jan Lillhök
- Swedish Radiation Safety Authority, Solna, Sweden
| | - Linda Eliasson
- Department of Physics, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Natalia Mojzeszek
- Institute of Nuclear Physics, Polish Academy of Sciences, (IFJ PAN), Krakow, Poland
| | - Malgorzata Liszka
- Institute of Nuclear Physics, Polish Academy of Sciences, (IFJ PAN), Krakow, Poland
- The Skandion Clinic, Uppsala, Sweden
| | - Ali Alkhiat
- The Skandion Clinic, Uppsala, Sweden
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden
| | - Vladimir Mares
- Helmholtz Zentrum München, Institute of Radiation Medicine, Neuherberg, Germany
| | - François Trompier
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-Santé, Fontenay-aux-Roses, France
| | - Sebastian Trinkl
- Helmholtz Zentrum München, Institute of Radiation Medicine, Neuherberg, Germany
- Federal Office for Radiation Protection, Neuherberg, Germany
| | | | | | - Carles Domingo
- Departament de Física, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Ondrej Ploc
- Department of Radiation Dosimetry, Nuclear Physics Institute of the Czech Academy of Sciences (CAS), Prague, Czechia
| | - Roger Harrison
- Faculty of Medical Sciences, University of Newcastle upon Tyne, Newcastle Upon Tyne, United Kingdom
| | - Pawel Olko
- Institute of Nuclear Physics, Polish Academy of Sciences, (IFJ PAN), Krakow, Poland
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Eliasson L, Lillhök J, Bäck T, Billnert-Maróti R, Dasu A, Liszka M. Range-shifter effects on the stray field in proton therapy measured with the variance–covariance method. Front Oncol 2022; 12:882230. [PMID: 35982965 PMCID: PMC9380888 DOI: 10.3389/fonc.2022.882230] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 07/05/2022] [Indexed: 01/09/2023] Open
Abstract
Measurements in the stray radiation field from a proton therapy pencil beam at energies 70 and 146 MeV were performed using microdosimetric tissue-equivalent proportional counters (TEPCs). The detector volumes were filled with a propane-based tissue-equivalent gas at low pressure simulating a mean chord length of 2 μm in tissue. Investigations were performed with and without a beam range shifter, and with different air gaps between the range shifter and a solid water phantom. The absorbed dose, the dose-mean lineal energy, and the dose equivalent were determined for different detector positions using the variance–covariance method. The influence from beam energy, detector- and range-shifter positions on absorbed dose, LET, and dose equivalent were investigated. Monte Carlo simulations of the fluence, detector response, and absorbed dose contribution from different particles were performed with MCNP 6.2. The simulated dose response for protons, neutrons, and photons were compared with, and showed good agreement with, previously published experimental data. The simulations also showed that the TEPC absorbed dose agrees well with the ambient absorbed dose for neutron energies above 20 MeV. The results illustrate that changes in both dose and LET variations in the stray radiation field can be identified from TEPC measurements using the variance–covariance method. The results are in line with the changes seen in the simulated relative dose contributions from different particles associated with different proton energies and range-shifter settings. It is shown that the proton contribution scattered directly from the range shifter dominates in some situations, and although the LET of the radiation is decreased, the ambient dose equivalent is increased up to a factor of 3.
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Affiliation(s)
- Linda Eliasson
- Department of Physics, KTH, Stockholm, Sweden
- *Correspondence: Linda Eliasson,
| | - Jan Lillhök
- The Swedish Radiation Safety Authority, Solna, Sweden
| | | | | | - Alexandru Dasu
- Medical Radiation Sciences, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
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10
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De Saint-Hubert M, Verbeek N, Bäumer C, Esser J, Wulff J, Nabha R, Van Hoey O, Dabin J, Stuckmann F, Vasi F, Radonic S, Boissonnat G, Schneider U, Rodriguez M, Timmermann B, Thierry-Chef I, Brualla L. Validation of a Monte Carlo Framework for Out-of-Field Dose Calculations in Proton Therapy. Front Oncol 2022; 12:882489. [PMID: 35756661 PMCID: PMC9213663 DOI: 10.3389/fonc.2022.882489] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/04/2022] [Indexed: 11/30/2022] Open
Abstract
Proton therapy enables to deliver highly conformed dose distributions owing to the characteristic Bragg peak and the finite range of protons. However, during proton therapy, secondary neutrons are created, which can travel long distances and deposit dose in out-of-field volumes. This out-of-field absorbed dose needs to be considered for radiation-induced secondary cancers, which are particularly relevant in the case of pediatric treatments. Unfortunately, no method exists in clinics for the computation of the out-of-field dose distributions in proton therapy. To help overcome this limitation, a computational tool has been developed based on the Monte Carlo code TOPAS. The purpose of this work is to evaluate the accuracy of this tool in comparison to experimental data obtained from an anthropomorphic phantom irradiation. An anthropomorphic phantom of a 5-year-old child (ATOM, CIRS) was irradiated for a brain tumor treatment in an IBA Proteus Plus facility using a pencil beam dedicated nozzle. The treatment consisted of three pencil beam scanning fields employing a lucite range shifter. Proton energies ranged from 100 to 165 MeV. A median dose of 50.4 Gy(RBE) with 1.8 Gy(RBE) per fraction was prescribed to the initial planning target volume (PTV), which was located in the cerebellum. Thermoluminescent detectors (TLDs), namely, Li-7-enriched LiF : Mg, Ti (MTS-7) type, were used to detect gamma radiation, which is produced by nuclear reactions, and secondary as well as recoil protons created out-of-field by secondary neutrons. Li-6-enriched LiF : Mg,Cu,P (MCP-6) was combined with Li-7-enriched MCP-7 to measure thermal neutrons. TLDs were calibrated in Co-60 and reported on absorbed dose in water per target dose (μGy/Gy) as well as thermal neutron dose equivalent per target dose (μSv/Gy). Additionally, bubble detectors for personal neutron dosimetry (BD-PND) were used for measuring neutrons (>50 keV), which were calibrated in a Cf-252 neutron beam to report on neutron dose equivalent dose data. The Monte Carlo code TOPAS (version 3.6) was run using a phase-space file containing 1010 histories reaching an average standard statistical uncertainty of less than 0.2% (coverage factor k = 1) on all voxels scoring more than 50% of the maximum dose. The primary beam was modeled following a Fermi–Eyges description of the spot envelope fitted to measurements. For the Monte Carlo simulation, the chemical composition of the tissues represented in ATOM was employed. The dose was tallied as dose-to-water, and data were normalized to the target dose (physical dose) to report on absorbed doses per target dose (mSv/Gy) or neutron dose equivalent per target dose (μSv/Gy), while also an estimate of the total organ dose was provided for a target dose of 50.4 Gy(RBE). Out-of-field doses showed absorbed doses that were 5 to 6 orders of magnitude lower than the target dose. The discrepancy between TLD data and the corresponding scored values in the Monte Carlo calculations involving proton and gamma contributions was on average 18%. The comparison between the neutron equivalent doses between the Monte Carlo simulation and the measured neutron doses was on average 8%. Organ dose calculations revealed the highest dose for the thyroid, which was 120 mSv, while other organ doses ranged from 18 mSv in the lungs to 0.6 mSv in the testes. The proposed computational method for routine calculation of the out-of-the-field dose in proton therapy produces results that are compatible with the experimental data and allow to calculate out-of-field organ doses during proton therapy.
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Affiliation(s)
- Marijke De Saint-Hubert
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Nico Verbeek
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Faculty of Medicine, University of Duisburg-Essen, Essen, Germany
| | - Christian Bäumer
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Radiation Oncology and Imaging, German Cancer Consortium DKTK, Heidelberg, Germany.,Department of Physics, TU Dortmund University, Dortmund, Germany
| | - Johannes Esser
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Faculty of Mathematics and Science Institute of Physics and Medical Physics. Heinrich-Heine University, Düsseldorf, Germany
| | - Jörg Wulff
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany
| | - Racell Nabha
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Olivier Van Hoey
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Jérémie Dabin
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Florian Stuckmann
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,Faculty of Mathematics and Science Institute of Physics and Medical Physics. Heinrich-Heine University, Düsseldorf, Germany.,Klinikum Fulda GAG, Universitätsmedizin Marburg, Fulda, Zurich, Germany
| | - Fabiano Vasi
- Physik Institut, Universität Zürich, Zürich, Switzerland
| | | | | | - Uwe Schneider
- Physik Institut, Universität Zürich, Zürich, Switzerland
| | - Miguel Rodriguez
- Hospital Paitilla, Panama City, Panama.,Instituto de Investigaciones Cientificas y de Alta Tecnología INDICASAT-AIP, Panama City, Panama
| | - Beate Timmermann
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Faculty of Medicine, University of Duisburg-Essen, Essen, Germany.,Radiation Oncology and Imaging, German Cancer Consortium DKTK, Heidelberg, Germany.,Department of Particle Therapy, University Hospital Essen, Essen, Germany
| | - Isabelle Thierry-Chef
- Radiation Programme, Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain.,University Pompeu Fabra, Barcelona, Spain.,CIBER Epidemiología y Salud Pública, Madrid, Spain
| | - Lorenzo Brualla
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Faculty of Medicine, University of Duisburg-Essen, Essen, Germany
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11
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Shrestha S, Newhauser WD, Donahue WP, Pérez-Andújar A. Stray neutron radiation exposures from proton therapy: physics-based analytical models of neutron spectral fluence, kerma and absorbed dose. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac7377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 05/25/2022] [Indexed: 11/11/2022]
Abstract
Abstract
Objective. Patients who receive proton beam therapy are exposed to unwanted stray neutrons. Stray radiations increase the risk of late effects in normal tissues, such as second cancers and cataracts, and may cause implanted devices such as pacemakers to malfunction. Compared to therapeutic beams, little attention has been paid to modeling stray neutron exposures. In the past decade, substantial progress was made to develop semiempirical models of stray neutron dose equivalent, but models to routinely calculate neutron absorbed dose and kerma are still lacking. The objective of this work was to develop a new physics based analytical model to calculate neutron spectral fluence, kerma, and absorbed dose in a water phantom. Approach. We developed the model using dosimetric data from Monte Carlo simulations and neutron kerma coefficients from the literature. The model explicitly considers the production, divergence, scattering, and attenuation of neutrons. Neutron production was modeled for 120–250 MeV proton beams impinging on a variety of materials. Fluence, kerma and dose calculations were performed in a 30 × 180 × 44 cm3 phantom at points up to 43 cm in depth and 80 cm laterally. Main Results. Predictions of the analytical model agreed reasonably with corresponding values from Monte Carlo simulations, with a mean difference in average energy deposited of 20%, average kerma coefficient of 21%, and absorbed dose to water of 49%. Significance. The analytical model is simple to implement and use, requires less configuration data that previously reported models, and is computationally fast. This model appears potentially suitable for integration in treatment planning system, which would enable risk calculations in prospective and retrospective cases, providing a powerful tool for epidemiological studies and clinical trials.
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12
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McAuley GA, Lim CJ, Teran AV, Slater JD, Wroe AJ. Monte Carlo evaluation of high-gradient magnetically focused planar proton minibeams in a passive nozzle. Phys Med Biol 2022; 67. [PMID: 35421853 DOI: 10.1088/1361-6560/ac678b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 04/14/2022] [Indexed: 11/12/2022]
Abstract
Objective. To investigate the potential of using a single quadrupole magnet with a high magnetic field gradient to create planar minibeams suitable for clinical applications of proton minibeam radiation therapy.Approach. We performed Monte Carlo simulations involving single quadrupole Halbach cylinders in a passively scattered nozzle in clinical use for proton therapy. Pencil beams produced by the nozzle of 10-15 mm initial diameters and particle range of ∼10-20 cm in water were focused by magnets with field gradients of 225-350 T m-1and cylinder lengths of 80-110 mm to produce very narrow elongated (planar) beamlets. The corresponding dose distributions were scored in a water phantom. Composite minibeam dose distributions composed from three beamlets were created by laterally shifting copies of the single beamlet distribution to either side of a central beamlet. Modulated beamlets (with 18-30 mm nominal central SOBP) and corresponding composite dose distributions were created in a similar manner. Collimated minibeams were also compared with beams focused using one magnet/particle range combination.Main results. The focusing magnets produced planar beamlets with minimum lateral FWHM of ∼1.1-1.6 mm. Dose distributions composed from three unmodulated beamlets showed a high degree of proximal spatial fractionation and a homogeneous target dose. Maximal peak-to-valley dose ratios (PVDR) for the unmodulated beams ranged from 32 to 324, and composite modulated beam showed maximal PVDR ranging from 32 to 102 and SOBPs with good target dose coverage.Significance.Advantages of the high-gradient magnets include the ability to focus beams with phase space parameters that reflect beams in operation today, and post-waist particle divergence allowing larger beamlet separations and thus larger PVDR. Our results suggest that high gradient quadrupole magnets could be useful to focus beams of moderate emittance in clinical proton therapy.
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Affiliation(s)
- Grant A McAuley
- Department of Radiation Medicine, Loma Linda University, Loma Linda CA, United States of America
| | - Crystal J Lim
- School of Medicine, Loma Linda University, Loma Linda, CA United States of America
| | - Anthony V Teran
- Department of Radiation Medicine, Loma Linda University, Loma Linda CA, United States of America.,Orange County CyberKnife and Radiation Oncology Center, Fountain Valley, CA, United States of America
| | - Jerry D Slater
- Department of Radiation Medicine, Loma Linda University, Loma Linda CA, United States of America
| | - Andrew J Wroe
- School of Medicine, Loma Linda University, Loma Linda, CA United States of America.,Department of Radiation Oncology, Miami Cancer Institute, Miami, FL, United States of America.,Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
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13
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Zorloni G, Bosmans G, Brall T, Caresana M, De Saint-Hubert M, Domingo C, Ferrante C, Ferrulli F, Kopec R, Leidner J, Mares V, Nabha R, Olko P, Caballero-Pacheco MÁ, Ruehm W, Silari M, Stolarczyk L, Swakon J, Tisi M, Trinkl S, Van Hoey O, Vilches-Freixas G. Joint EURADOS WG9-WG11 rem-counter intercomparison in a Mevion S250i proton therapy facility with Hyperscan pulsed synchrocyclotron. Phys Med Biol 2022; 67:075005. [PMID: 35259730 DOI: 10.1088/1361-6560/ac5b9c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Objective Proton therapy is gaining popularity because of the improved dose delivery over conventional radiation therapy. The secondary dose to healthy tissues is dominated by secondary neutrons. Commercial rem-counters are valuable instruments for the on-line assessment of neutron ambient dose equivalent (H*(10)). In general, however, a priori knowledge of the type of facility and of the radiation field is required for the proper choice of any survey meter. The novel Mevion S250i Hyperscan synchrocyclotron mounts the accelerator directly on the gantry. It provides a scanned 227 MeV proton beam, delivered in pulses with a pulse width of 10 µs at 750 Hz frequency, which is afterwards degraded in energy by a range shifter modulator system. This environment is particularly challenging for commercial rem-counters; therefore, we tested the reliability of some of the most widespread rem-counters to understand their limits in the Mevion S250i stray neutron field. Approach This work, promoted by the European Radiation Dosimetry Group (EURADOS), describes a rem-counter intercomparison at the Maastro Proton Therapy centre in the Netherlands, which houses the novel Mevion S250i Hyperscan system. Several rem-counters were employed in the intercomparison (LUPIN, LINUS, WENDI-II, LB6411, NM2B-458, NM2B-495Pb), which included simulation of a patient treatment protocol employing a water tank phantom. The outcomes of the experiment were compared with models and data from the literature. Main results We found that only the LUPIN allowed for a correct assessment of H*(10) within a 20% uncertainty. All other rem-counters underestimated the reference H*(10) by factors from 2 to more than 10, depending on the detector model and on the neutron dose per pulse. In pulsed fields, the neutron dose per pulse is a fundamental parameter, while the average neutron dose rate is a secondary quantity. An average 150-200 µSv/GyRBE neutron H*(10) at various positions around the phantom and at distances between 186 cm and 300 cm from it was measured per unit therapeutic dose delivered to the target. Significance Our results are partially in line with results obtained at similar Mevion facilities employing passive energy modulation. Comparisons with facilities employing active energy modulation confirmed that the neutron H*(10) can increase up to more than a factor of 10 when passive energy modulation is employed. The challenging environment of the Mevion stray neutron field requires the use of specific rem-counters sensitive to high-energy neutrons (up to a few hundred MeV) and specifically designed to withstand pulsed neutron fields.
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Affiliation(s)
| | - Geert Bosmans
- Maastricht University Medical Centre+ Oncology Centre, P. Debyelaan 25, Maastricht, Limburg, 6229, NETHERLANDS
| | - Thomas Brall
- Helmotz Zentrum Munchen, Ingolstädter Landstr. 1, Neuherberg, 85764, GERMANY
| | - Marco Caresana
- Energy, Politecnico di Milano, via Lambruschini 4, Milano, 20133, ITALY
| | - Marijke De Saint-Hubert
- Radiation protection Dosimetry and Calibration Expert Group, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, Mol, 2400, BELGIUM
| | - Carles Domingo
- Departament de Fisica, Universidad Autonoma de Barcelona, Plaça Cívica, Bellaterra, 08193 , SPAIN
| | | | | | - Renata Kopec
- Institute of Nuclear Physics Polish Academy of Science, Walerego Eljasza Radzikowskiego 152, Krakow, 31-342, POLAND
| | | | - Vladimir Mares
- Helmholtz Zentrum Muenchen Deutsche Forschungszentrum fuer Gesundheit und Umwelt, D-85758 Neuherberg, Neuherberg, 85764 , GERMANY
| | - Racell Nabha
- Radiation protection Dosimetry and Calibration Expert Group, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, Mol, 2400, BELGIUM
| | - Pawel Olko
- PAN, Polish Academy of Sciences, ul Radzikowskiego 152, PL 31-342, Krakow, Kraków, 31-342, POLAND
| | | | - Werner Ruehm
- Helmholtz Center Munich, Ingolstädter Landstr. 1, Neuherberg, 85764 , GERMANY
| | - Marco Silari
- CERN, Esplanade des Particules 1, Geneve, 1211, SWITZERLAND
| | - Liliana Stolarczyk
- Dansk Center for Partikelterapi, Aarhus University Hospital Skejby, Palle Juul-Jensens Boulevard 25, Aarhus, 8200, DENMARK
| | - Jan Swakon
- Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, Krakow, 31-342, POLAND
| | - Marco Tisi
- Helmholtz Center Munich German Research Center for Environmental Health, Ingolstädter Landstr. 1, Neuherberg, Bayern, 85764, GERMANY
| | - Sebastian Trinkl
- Bundesamt fur Strahlenschutz Neuherberg, Ingolstädter Landstraße 1, Neuherberg, 85764, GERMANY
| | - Olivier Van Hoey
- Studiecentrum voor Kernenergie, Boeretang 200, Mol, 2400, BELGIUM
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14
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The influence of nuclear models and Monte Carlo radiation transport codes on stray neutron dose estimations in proton therapy. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2021.106693] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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15
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Tisi M, Mares V, Schreiber J, Englbrecht FS, Rühm W. Geant4 Monte Carlo simulation study of the secondary radiation fields at the laser-driven ion source LION. Sci Rep 2021; 11:24418. [PMID: 34952912 PMCID: PMC8709851 DOI: 10.1038/s41598-021-03897-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 12/09/2021] [Indexed: 11/09/2022] Open
Abstract
At the Center for Advanced Laser Applications (CALA), Garching, Germany, the LION (Laser-driven ION Acceleration) experiment is being commissioned, aiming at the production of laser-driven bunches of protons and light ions with multi-MeV energies and repetition frequency up to 1 Hz. A Geant4 Monte Carlo-based study of the secondary neutron and photon fields expected during LION's different commissioning phases is presented. Goal of this study is the characterization of the secondary radiation environment present inside and outside the LION cave. Three different primary proton spectra, taken from experimental results reported in the literature and representative of three different future stages of the LION's commissioning path are used. Together with protons, also electrons are emitted through laser-target interaction and are also responsible for the production of secondary radiation. For the electron component of the three source terms, a simplified exponential model is used. Moreover, in order to reduce the simulation complexity, a two-components simplified geometrical model of proton and electron sources is proposed. It has been found that the radiation environment inside the experimental cave is either dominated by photons or neutrons depending on the position in the room and the source term used. The higher the intensity of the source, the higher the neutron contribution to the total dose for all scored positions. Maximum neutron and photon ambient dose equivalent values normalized to 109 simulated incident primaries were calculated at the exit of the vacuum chamber, where values of about 85 nSv (109 primaries)-1 and 1.0 μSv (109 primaries)-1 were found.
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Affiliation(s)
- M Tisi
- Institute of Radiation Medicine, Helmholtz Zentrum München, Neuherberg, Germany.
| | - V Mares
- Institute of Radiation Medicine, Helmholtz Zentrum München, Neuherberg, Germany
| | - J Schreiber
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität, Garching bei München, Germany
- Max-Planck-Institute for Quantum Optics, Garching bei München, Germany
| | - F S Englbrecht
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität, Garching bei München, Germany
| | - W Rühm
- Institute of Radiation Medicine, Helmholtz Zentrum München, Neuherberg, Germany
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16
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Vedelago J, Geser FA, Muñoz ID, Stabilini A, Yukihara EG, Jaekel O. Assessment of secondary neutrons in particle therapy by Monte Carlo simulations. Phys Med Biol 2021; 67. [PMID: 34905742 DOI: 10.1088/1361-6560/ac431b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/14/2021] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The purpose of this study is to estimate the energy and angular distribution of secondary neutrons inside a phantom in hadron therapy, which will support decisions on detector choice and experimental setup design for in-phantom secondary neutron measurements. APPROACH Dedicated Monte Carlo simulations were implemented, considering clinically relevant energies of protons, helium and carbon ions. Since scored quantities can vary from different radiation transport models, the codes FLUKA, TOPAS and MCNP were used. The geometry of an active scanning beam delivery system for heavy ion treatment was implemented, and simulations of pristine and spread-out Bragg peaks were carried out. Previous studies, focused on specific ion types or single energies, are qualitatively in agreement with the obtained results. MAIN RESULTS The secondary neutrons energy distributions present a continuous spectrum with two peaks, one centred on the thermal/epithermal region, and one on the high-energy region, with the most probable energy ranging from 19 MeV up to 240 MeV, depending on the ion type and its initial energy. The simulations show that the secondary neutron energies may exceed 400 MeV and, therefore, suitable neutron detectors for this energy range shall be needed. Additionally, the angular distribution of the low energy neutrons is quite isotropic, whereas the fast/relativistic neutrons are mainly scattered in the down-stream direction. SIGNIFICANCE It would be possible to minimize the influence of the heavy ions when measuring the neutron-generated recoil protons by selecting appropriate measurement positions within the phantom. Although there are discrepancies among the three Monte Carlo codes, the results agree qualitatively and in order of magnitude, being sufficient to support further investigations with the ultimate goal of mapping the secondary neutron doses both in- and out-of-field in hadrontherapy. The obtained secondary neutron spectra are available as supplementary material.
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Affiliation(s)
- José Vedelago
- German Cancer Research Centre, Im Neuenheimer Feld 280, Heidelberg, 69120, GERMANY
| | - Federico A Geser
- Paul Scherrer Institut, Forschungsstrasse 111, Villigen PSI, 5232, SWITZERLAND
| | - Iván D Muñoz
- German Cancer Research Centre, Im Neuenheimer Feld 280, Heidelberg, 69120, GERMANY
| | - Alberto Stabilini
- Paul Scherrer Institut, Forschungsstrasse 111, Villigen PSI, 5235, SWITZERLAND
| | - Eduardo G Yukihara
- Paul Scherrer Institut, Forschungsstrasse 111, Villigen PSI, 5232, SWITZERLAND
| | - Oliver Jaekel
- German Cancer Research Centre, Im Neuenheimer Feld 280, Heidelberg, 69120, GERMANY
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17
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Behrends C, Bäumer C, Verbeek N, Ehlert J, Prasad R, Wulff J, Lühr A, Timmermann B. Technical note: Providing proton fields down to the few-MeV level at clinical pencil beam scanning facilities for radiobiological experiments. Med Phys 2021; 49:666-674. [PMID: 34855985 DOI: 10.1002/mp.15388] [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: 08/23/2021] [Revised: 11/03/2021] [Accepted: 11/18/2021] [Indexed: 11/08/2022] Open
Abstract
PURPOSE The adequate performance of radiobiological experiments using clinical proton beams typically requires substantial preparations to provide the appropriate setup for specific experiments. Providing radiobiologically interesting low-energy protons is a particular challenge, due to various physical effects that become more pronounced with larger absorber thickness and smaller proton energy. This work demonstrates the generation of decelerated low-energy protons from a clinical proton beam. METHODS Monte Carlo simulations of proton energy spectra were performed for energy absorbers with varying thicknesses to reduce the energy of the clinical proton beam down to the few-MeV level corresponding to μ m-ranges. In this way, a setup with an optimum thickness of the absorber with a maximum efficiency of the proton fluence for the provisioning of low-energy protons is supposed to be found. For the specific applications of 2.5-3.3 MeV protons and α -particle range equivalent protons, the relative depth dose was measured and simulated together with the dose-averaged linear energy transfer (LETd) distribution. RESULTS The resulting energy spectra from Monte Carlo simulations indicate an optimal absorber thickness for providing low-energy protons with maximum efficiency of proton fluence at an user-requested energy range for experiments. For instance, providing energies lower than 5 MeV, an energy spectrum with a relative total efficiency of 38.6 % to the initial spectrum was obtained with the optimal setup. The measurements of the depth dose, compared to the Monte Carlo simulations, showed that the dosimetry of low-energy protons works and protons with high LETd down to the range of α -particles can be produced. CONCLUSIONS This work provides a method for generating all clinically and radiobiologically relevant energies - especially down to the few-MeV level - at one clinical facility with pencil beam scanning. Thereby, it enables radiobiological experiments under environmentally uniform conditions.
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Affiliation(s)
- Carina Behrends
- West German Proton Therapy Centre Essen (WPE), 45147 Essen, Germany.,Department of Physics, TU Dortmund University, 44227 Dortmund, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, 45147 Essen, Germany
| | - Christian Bäumer
- West German Proton Therapy Centre Essen (WPE), 45147 Essen, Germany.,Department of Physics, TU Dortmund University, 44227 Dortmund, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, 45147 Essen, Germany.,German Cancer Consortium (DKTK), 69120 Heidelberg, Germany
| | - Nico Verbeek
- West German Proton Therapy Centre Essen (WPE), 45147 Essen, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, 45147 Essen, Germany.,Faculty of Medicine, University of Duisburg-Essen, 45147 Essen, Germany
| | - Jens Ehlert
- Institute for Laser and Plasma Physics, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany.,Department of Haematology, Oncology and Clinical Immunology, Heinrich-Heine-University Düsseldorf, Medical Faculty, 40225 Düsseldorf, Germany
| | - Rajendra Prasad
- Institute for Laser and Plasma Physics, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Jörg Wulff
- West German Proton Therapy Centre Essen (WPE), 45147 Essen, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, 45147 Essen, Germany
| | - Armin Lühr
- Department of Physics, TU Dortmund University, 44227 Dortmund, Germany
| | - Beate Timmermann
- West German Proton Therapy Centre Essen (WPE), 45147 Essen, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, 45147 Essen, Germany.,German Cancer Consortium (DKTK), 69120 Heidelberg, Germany.,Faculty of Medicine, University of Duisburg-Essen, 45147 Essen, Germany.,Department of Particle Therapy, University Hospital Essen, 45147 Essen, Germany
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Yeom YS, Kuzmin G, Griffin K, Mille M, Polf J, Langner U, Jung JW, Lee C, Ellis D, Shin J, Lee C. A Monte Carlo model for organ dose reconstruction of patients in pencil beam scanning (PBS) proton therapy for epidemiologic studies of late effects. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2020; 40:225-242. [PMID: 31509813 PMCID: PMC10065358 DOI: 10.1088/1361-6498/ab437d] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Significant efforts such as the Pediatric Proton/Photon Consortium Registry (PPCR) involving multiple proton therapy centers have been made to conduct collaborative studies evaluating outcomes following proton therapy. As a groundwork dosimetry effort for the late effect investigation, we developed a Monte Carlo (MC) model of proton pencil beam scanning (PBS) to estimate organ/tissue doses of pediatric patients at the Maryland Proton Treatment Center (MPTC), one of the proton centers involved in the PPCR. The MC beam modeling was performed using the TOPAS (TOol for PArticle Simulation) MC code and commissioned to match measurement data within 1% for range, and 0.3 mm for spot sizes. The established MC model was then tested by calculating organ/tissue doses for sample intracranial and craniospinal irradiations on whole-body pediatric computational human phantoms. The simulated dose distributions were compared with the treatment planning system dose distributions, showing the 3 mm/3% gamma index passing rates of 94%-99%, validating our simulations with the MC model. The calculated organ/tissue doses per prescribed doses for the craniospinal irradiations (1 mGy Gy-1 to 1 Gy Gy-1) were generally much higher than those for the intracranial irradiations (2.1 μGy Gy-1 to 0.1 Gy Gy-1), which is due to the larger field coverage of the craniospinal irradiations. The largest difference was observed at the adrenal dose, i.e. ∼3000 times. In addition, the calculated organ/tissue doses were compared with those calculated with a simplified MC model, showing that the beam properties (i.e. spot size, spot divergence, mean energy, and energy spread) do not significantly influence dose calculations despite the limited irradiation cases. This implies that the use of the MC model commissioned to the MPTC measurement data might be dosimetrically acceptable for patient dose reconstructions at other proton centers particularly when their measurement data are unavailable. The developed MC model will be used to reconstruct organ/tissue doses for MPTC pediatric patients collected in the PPCR.
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Affiliation(s)
- Yeon Soo Yeom
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, United States of America
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Hälg RA, Schneider U. Neutron dose and its measurement in proton therapy-current State of Knowledge. Br J Radiol 2020; 93:20190412. [PMID: 31868525 PMCID: PMC7066952 DOI: 10.1259/bjr.20190412] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 12/06/2019] [Accepted: 12/19/2019] [Indexed: 12/26/2022] Open
Abstract
Proton therapy has shown dosimetric advantages over conventional radiation therapy using photons. Although the integral dose for patients treated with proton therapy is low, concerns were raised about late effects like secondary cancer caused by dose depositions far away from the treated area. This is especially true for neutrons and therefore the stray dose contribution from neutrons in proton therapy is still being investigated. The higher biological effectiveness of neutrons compared to photons is the main cause of these concerns. The gold-standard in neutron dosimetry is measurements, but performing neutron measurements is challenging. Different approaches have been taken to overcome these difficulties, for instance with newly developed neutron detectors. Monte Carlo simulations is another common technique to assess the dose from secondary neutrons. Measurements and simulations are used to develop analytical models for fast neutron dose estimations. This article tries to summarize the developments in the different aspects of neutron dose in proton therapy since 2017. In general, low neutron doses have been reported, especially in active proton therapy. Although the published biological effectiveness of neutrons relative to photons regarding cancer induction is higher, it is unlikely that the neutron dose has a large impact on the second cancer risk of proton therapy patients.
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Isobe T, Mori Y, Takei H, Sato E, Sakae T. [14. Biological Dose and Effects of Neutrons in Proton Beam Therapy]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2020; 76:863-869. [PMID: 32814743 DOI: 10.6009/jjrt.2020_jsrt_76.8.863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
| | | | | | - Eisuke Sato
- Faculty of Health Science, Juntendo University
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Combe R, Arbor N, el Bitar Z, Higueret S, Husson D. Conception of a New Recoil Proton Telescope for Real-Time Neutron Spectrometry in Proton-Therapy. EPJ WEB OF CONFERENCES 2018. [DOI: 10.1051/epjconf/201817009001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Neutrons are the main type of secondary particles emitted in proton-therapy. Because of the risk of secondary cancer and other late occurring effects, the neutron dose should be included in the out-of-field dose calculations. A neutron spectrometer has to be used to take into account the energy dependence of the neutron radiological weighting factor. Due to its high dependence on various parameters of the irradiation (beam, accelerator, patient), the neutron spectrum should be measured independently for each treatment.
The current reference method for the measurement of the neutron energy, the Bonner Sphere System, consists of several homogeneous polyethylene spheres with increasing diameters equipped with a proportional counter. It provides a highresolution reconstruction of the neutron spectrum but requires a time-consuming work of signal deconvolution. New neutron spectrometers are being developed, but the main experimental limitation remains the high neutron flux in proton therapy treatment rooms. A new model of a real-time neutron spectrometer, based on a Recoil Proton Telescope technology, has been developed at the IPHC. It enables a real-time high-rate reconstruction of the neutron spectrum from the measurement of the recoil proton trajectory and energy. A new fast-readout microelectronic integrated sensor, called FastPixN, has been developed for this specific purpose.A first prototype, able to detect neutrons between 5 and 20 MeV, has already been validated for metrology with the AMANDE facility at Cadarache. The geometry of the new Recoil Proton Telescope has been optimized via extensive Geant4 Monte Carlo simulations. Uncertainty sources have been carefully studied in order to improve simultaneously efficiency and energy resolution, and solutions have been found to suppress the various expected backgrounds. We are currently upgrading the prototype for secondary neutron detection in proton therapy applications.
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Kry SF, Bednarz B, Howell RM, Dauer L, Followill D, Klein E, Paganetti H, Wang B, Wuu CS, George Xu X. AAPM TG 158: Measurement and calculation of doses outside the treated volume from external-beam radiation therapy. Med Phys 2017; 44:e391-e429. [DOI: 10.1002/mp.12462] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 05/17/2017] [Accepted: 05/25/2017] [Indexed: 12/14/2022] Open
Affiliation(s)
- Stephen F. Kry
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Bryan Bednarz
- Department of Medical Physics; University of Wisconsin; Madison WI 53705 USA
| | - Rebecca M. Howell
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Larry Dauer
- Departments of Medical Physics/Radiology; Memorial Sloan-Kettering Cancer Center; New York NY 10065 USA
| | - David Followill
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Eric Klein
- Department of Radiation Oncology; Washington University; Saint Louis MO 63110 USA
| | - Harald Paganetti
- Department of Radiation Oncology; Massachusetts General Hospital and Harvard Medical School; Boston MA 02114 USA
| | - Brian Wang
- Department of Radiation Oncology; University of Louisville; Louisville KY 40202 USA
| | - Cheng-Shie Wuu
- Department of Radiation Oncology; Columbia University; New York NY 10032 USA
| | - X. George Xu
- Department of Mechanical, Aerospace, and Nuclear Engineering; Rensselaer Polytechnic Institute; Troy NY 12180 USA
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