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Rahimi R, Taylor M, Li X, Chen KL, MacLennan G, Murdoch E, Chang L, Parniani A, Wang P, Chawla A, Fan J, Kim D. Fetal dose assessment in a pregnant patient with brain tumor: A comparative study of proton PBS and 3DCRT/VMAT radiation therapy techniques. J Appl Clin Med Phys 2024; 25:e14394. [PMID: 38887816 PMCID: PMC11302808 DOI: 10.1002/acm2.14394] [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: 02/22/2024] [Revised: 04/11/2024] [Accepted: 04/23/2024] [Indexed: 06/20/2024] Open
Abstract
PURPOSE The treatment of brain tumors in pregnant patients poses challenges, as the out-of-field dose exposure to the fetus can potentially be harmful. A pregnant patient with prior radiation treatment was presented with a brain tumor at our clinic. This work reports on our pre-treatment study that compared fetal dose exposure between intensity-modulated proton therapy (IMPT) using pencil beam scanning (PBS) and conventional photon 3D conformal radiation therapy (3DCRT) and volumetric-modulated arc therapy (VMAT), and the subsequent pregnant patient's radiation treatment. MATERIALS AND METHODS Pre-treatment measurements of clinical plans, 3DCRT, VMAT, and IMPT, were conducted on a phantom. Measurements were performed using a device capable of neutron detections, closely following AAPM guidelines, TG158. For photon measurements, fetus shielding was utilized. On patient treatment days, which was determined to be proton treatment, shielding was used only during daily imaging for patient setup. Additionally, an in vivo measurement was conducted on the patient. RESULTS Measurements showed that IMPT delivered the lowest fetal dose, considering both photon and neutron out-of-field doses to the fetus, even when shielding was implemented for photon measurements. Additionally, the proton plans demonstrated superior treatment for the mother, a reirradiation case. CONCLUSION The patient was treated with proton therapy, and the baby was subsequently delivered at full term with no complications. This case study supports previous clinical findings and advocates for the expanded use of proton therapy in this patient population.
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Affiliation(s)
- Robabeh Rahimi
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | - Michael Taylor
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | - Xing Li
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | - Kuan Ling Chen
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | | | - Erin Murdoch
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | - Lienard Chang
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | - Ashkan Parniani
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | - Peng Wang
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | - Ashish Chawla
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | - Jiajin Fan
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
| | - Daniel Kim
- Radiation Oncology DepartmentInova Health SystemFairfaxVirginiaUSA
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Blommaert J, De Saint‐Hubert M, Depuydt T, Oldehinkel E, Poortmans P, Amant F, Lambrecht M. Challenges and opportunities for proton therapy during pregnancy. Acta Obstet Gynecol Scand 2024; 103:767-774. [PMID: 37491770 PMCID: PMC10993337 DOI: 10.1111/aogs.14645] [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] [Indexed: 07/27/2023]
Abstract
During pregnancy, the use of radiation therapy for cancer treatment is often considered impossible due to the assumed associated fetal risks. However, suboptimal treatment of pregnant cancer patients and unjustifiable delay in radiation therapy until after delivery can be harmful for both patient and child. In non-pregnant patients, proton-radiation therapy is increasingly administered because of its favorable dosimetric properties compared with photon-radiation therapy. Although data on the use of pencil beam scanning proton-radiation therapy during pregnancy are scarce, different case reports and dosimetric studies have indicated a more than 10-fold reduction in fetal radiation exposure compared with photon-radiation therapy. Nonetheless, the implementation of proton-radiation therapy during pregnancy requires complex fetal dosimetry for the neutron-dominated out-of-field radiation dose and faces a lack of clinical guidelines. Further exploration and standardization of proton-radiation therapy during pregnancy will be necessary to improve radiotherapeutic management of pregnant women with cancer and further reduce risks for their offspring.
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Affiliation(s)
| | | | - Tom Depuydt
- Department of OncologyKU LeuvenLeuvenBelgium
- Department of Radiation OncologyUniversity Hospitals LeuvenLeuvenBelgium
| | - Edwin Oldehinkel
- Department of Radiation OncologyUniversity Medical Center Groningen, University of GroningenGroningenthe Netherlands
| | - Philip Poortmans
- Radiation OncologyIridium Netwerk & University of AntwerpWilrijkBelgium
| | - Frederic Amant
- Department of OncologyKU LeuvenLeuvenBelgium
- Gynecologic Oncology, Antoni van LeeuwenhoekNetherlands Cancer InstituteAmsterdamThe Netherlands
- Division Gynecologic OncologyUniversity Hospitals LeuvenLeuvenBelgium
| | - Maarten Lambrecht
- Department of OncologyKU LeuvenLeuvenBelgium
- Department of Radiation OncologyUniversity Hospitals LeuvenLeuvenBelgium
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3
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Kopačin V, Brkić H, Ivković A, Kasabašić M, Knežević Ž, Majer M, Nodilo M, Turk T, Faj D. Development and validation of the low-cost pregnant female physical phantom for fetal dosimetry in MV photon radiotherapy. J Appl Clin Med Phys 2024; 25:e14240. [PMID: 38150580 PMCID: PMC10860449 DOI: 10.1002/acm2.14240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/27/2023] [Accepted: 11/27/2023] [Indexed: 12/29/2023] Open
Abstract
BACKGROUND Monte Carlo (MC) simulations or measurements in anthropomorphic phantoms are recommended for estimating fetal dose in pregnant patients in radiotherapy. Among the many existing phantoms, there is no commercially available physical phantom representing the entire pregnant woman. PURPOSE In this study, the development of a low-cost, physical pregnant female phantom was demonstrated using commercially available materials. This phantom is based on the previously published computational phantom. METHODS Three tissue substitution materials (soft tissue, lung and bone tissue substitution) were developed. To verify Tena's substitution tissue materials, their radiation properties were assessed and compared to ICRP and ICRU materials using MC simulations in MV radiotherapy beams. Validation of the physical phantom was performed by comparing fetal doses obtained by measurements in the phantom with fetal doses obtained by MC simulations in computational phantom, during an MV photon breast radiotherapy treatment. RESULTS Materials used for building Tena phantom are matched to ICRU materials using physical density, radiation absorption properties and effective atomic number. MC simulations showed that percentage depth doses of Tena and ICRU material comply within 5% for soft and lung tissue, up to 25 cm depth. In the bone tissue, the discrepancy is higher, but again within 5% up to the depth of 5 cm. When the phantom was used for fetal dose measurements in MV photon breast radiotherapy, measured fetal doses complied with fetal doses calculated using MC simulation within 15%. CONCLUSIONS Physical anthropomorphic phantom of pregnant patient can be manufactured using commercial materials and with low expenses. The files needed for 3D printing are now freely available. This enables further studies and comparison of numerical and physical experiments in diagnostic radiology or radiotherapy.
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Affiliation(s)
- Vjekoslav Kopačin
- Faculty of MedicineDepartment of RadiologyJ. J. Strossmayer University Osijek, University Hospital Center OsijekDepartment of Diagnostic and Interventional RadiologyOsijekCroatia
| | - Hrvoje Brkić
- Faculty of MedicineDepartment of Biophysics and Medical PhysicsJ. J. Strossmayer University OsijekOsijekCroatia
- Faculty of Dental Medicine and HealthDepartment of BiophysicsBiology and ChemistryJ. J. Strossmayer University OsijekOsijekCroatia
| | - Ana Ivković
- Faculty of MedicineDepartment of Biophysics and Medical PhysicsJ. J. Strossmayer University Osijek, University Hospital Center OsijekDepartment of Medical PhysicsOsijekCroatia
| | - Mladen Kasabašić
- Faculty of MedicineDepartment of Biophysics and Medical PhysicsJ. J. Strossmayer University Osijek, University Hospital Center OsijekDepartment of Medical PhysicsOsijekCroatia
| | - Željka Knežević
- Division of Materials ChemistryRuđer Bošković InstituteZagrebCroatia
| | - Marija Majer
- Division of Materials ChemistryRuđer Bošković InstituteZagrebCroatia
| | - Marijana Nodilo
- Division of Materials ChemistryRuđer Bošković InstituteZagrebCroatia
| | - Tajana Turk
- Faculty of MedicineDepartment of RadiologyJ. J. Strossmayer University Osijek, University Hospital Center OsijekDepartment of Diagnostic and Interventional RadiologyOsijekCroatia
| | - Dario Faj
- Faculty of MedicineDepartment of Biophysics and Medical PhysicsJ. J. Strossmayer University OsijekOsijekCroatia
- Faculty of Dental Medicine and HealthDepartment of BiophysicsBiology and ChemistryJ. J. Strossmayer University OsijekOsijekCroatia
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4
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Geser FA, Stabilini A, Christensen JB, Muñoz ID, Yukihara EG, Jäkel O, Vedelago J. A Monte Carlo study on the secondary neutron generation by oxygen ion beams for radiotherapy and its comparison to lighter ions. Phys Med Biol 2024; 69:015027. [PMID: 37995363 DOI: 10.1088/1361-6560/ad0f45] [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: 08/16/2023] [Accepted: 11/23/2023] [Indexed: 11/25/2023]
Abstract
Objective.To study the secondary neutrons generated by primary oxygen beams for cancer treatment and compare the results to those from primary protons, helium, and carbon ions. This information can provide useful insight into the positioning of neutron detectors in phantom for future experimental dose assessments.Approach.Mono-energetic oxygen beams and spread-out Bragg peaks were simulated using the Monte Carlo particle transport codesFLUktuierende KAskade, tool for particle simulation, and Monte Carlo N-Particle, with energies within the therapeutic range. The energy and angular distribution of the secondary neutrons were quantified.Main results.The secondary neutron spectra generated by primary oxygen beams present the same qualitative trend as for other primary ions. The energy distributions resemble continuous spectra with one peak in the thermal/epithermal region, and one other peak in the fast/relativistic region, with the most probable energy ranging from 94 up to 277 MeV and maximum energies exceeding 500 MeV. The angular distribution of the secondary neutrons is mainly downstream-directed for the fast/relativistic energies, whereas the thermal/epithermal neutrons present a more isotropic propagation. When comparing the four different primary ions, there is a significant increase in the most probable energy as well as the number of secondary neutrons per primary particle when increasing the mass of the primaries.Significance.Most previous studies have only presented results of secondary neutrons generated by primary proton beams. In this work, secondary neutrons generated by primary oxygen beams are presented, and the obtained energy and angular spectra are added as supplementary material. Furthermore, a comparison of the secondary neutron generation by the different primary ions is given, which can be used as the starting point for future studies on treatment plan comparison and secondary neutron dose optimisation. The distal penumbra after the maximum dose deposition appears to be a suitable location for in-phantom dose assessments.
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Affiliation(s)
- Federico A Geser
- Department of Radiation Safety and Security, Paul Scherrer Institute (PSI), Forschungsstrasse 111, Villigen PSI 5232, Switzerland
| | - Alberto Stabilini
- Department of Radiation Safety and Security, Paul Scherrer Institute (PSI), Forschungsstrasse 111, Villigen PSI 5232, Switzerland
| | - Jeppe B Christensen
- Department of Radiation Safety and Security, Paul Scherrer Institute (PSI), Forschungsstrasse 111, Villigen PSI 5232, Switzerland
| | - Iván D Muñoz
- Department of Physics and Astronomy, Heidelberg University, Im Neuenheimer Feld 226, Heidelberg D-69120, Germany
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - Eduardo G Yukihara
- Department of Radiation Safety and Security, Paul Scherrer Institute (PSI), Forschungsstrasse 111, Villigen PSI 5232, Switzerland
| | - Oliver Jäkel
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
- Heidelberg Ion Beam Therapy Center (HIT), Department of Radiation Oncology, University Hospital Heidelberg (UKHD), Im Neuenheimer Feld 450, Heidelberg D-69120, Germany
| | - José Vedelago
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
- Department of Radiation Oncology, Heidelberg University Hospital (UKHD), Im Neuenheimer Feld 400, Heidelberg D-69120, Germany
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5
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Oancea C, Solc J, Bourgouin A, Granja C, Jakubek J, Pivec J, Riemer F, Vykydal Z, Worm S, Marek L. Thermal neutron detection and track recognition method in reference and out-of-field radiotherapy FLASH electron fields using Timepix3 detectors. Phys Med Biol 2023; 68:185017. [PMID: 37607560 DOI: 10.1088/1361-6560/acf2e1] [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: 02/28/2023] [Accepted: 08/22/2023] [Indexed: 08/24/2023]
Abstract
Objective.This work presents a method for enhanced detection, imaging, and measurement of the thermal neutron flux.Approach. Measurements were performed in a water tank, while the detector is positioned out-of-field of a 20 MeV ultra-high pulse dose rate electron beam. A semiconductor pixel detector Timepix3 with a silicon sensor partially covered by a6LiF neutron converter was used to measure the flux, spatial, and time characteristics of the neutron field. To provide absolute measurements of thermal neutron flux, the detection efficiency calibration of the detectors was performed in a reference thermal neutron field. Neutron signals are recognized and discriminated against other particles such as gamma rays and x-rays. This is achieved by the resolving power of the pixel detector using machine learning algorithms and high-resolution pattern recognition analysis of the high-energy tracks created by thermal neutron interactions in the converter.Main results. The resulting thermal neutrons equivalent dose was obtained using conversion factor (2.13(10) pSv·cm2) from thermal neutron fluence to thermal neutron equivalent dose obtained by Monte Carlo simulations. The calibrated detectors were used to characterize scattered radiation created by electron beams. The results at 12.0 cm depth in the beam axis inside of the water for a delivered dose per pulse of 1.85 Gy (pulse length of 2.4μs) at the reference depth, showed a contribution of flux of 4.07(8) × 103particles·cm-2·s-1and equivalent dose of 1.73(3) nSv per pulse, which is lower by ∼9 orders of magnitude than the delivered dose.Significance. The presented methodology for in-water measurements and identification of characteristic thermal neutrons tracks serves for the selective quantification of equivalent dose made by thermal neutrons in out-of-field particle therapy.
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Affiliation(s)
- Cristina Oancea
- ADVACAM, U Pergamenky 12, 170 00 Prague 7, Czech Republic
- University of Bucharest, Bucharest, Romania
| | - Jaroslav Solc
- Czech Metrology Institute, Okruzni 31, 638 00 Brno, Czech Republic
| | - Alexandra Bourgouin
- Dosimetry for Radiation Therapy and Diagnostic Radiology, Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, 38116, Germany
| | - Carlos Granja
- ADVACAM, U Pergamenky 12, 170 00 Prague 7, Czech Republic
| | - Jan Jakubek
- ADVACAM, U Pergamenky 12, 170 00 Prague 7, Czech Republic
| | - Jiri Pivec
- ADVACAM, U Pergamenky 12, 170 00 Prague 7, Czech Republic
| | - Felix Riemer
- Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, 15738 Zeuthen, Germany
| | - Zdenek Vykydal
- Czech Metrology Institute, Okruzni 31, 638 00 Brno, Czech Republic
| | - Steven Worm
- Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, 15738 Zeuthen, Germany
| | - Lukas Marek
- ADVACAM, U Pergamenky 12, 170 00 Prague 7, Czech Republic
- Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
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Wong YM, Koh CWY, Lew KS, Chua CGA, Nei W, Tan HQ, Lee JCL, Mazonakis M, Damilakis J. A review on fetal dose in Radiotherapy: A historical to contemporary perspective. Phys Med 2023; 105:102513. [PMID: 36565555 DOI: 10.1016/j.ejmp.2022.102513] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/09/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
This paper aims to review on fetal dose in radiotherapy and extends and updates on a previous work1 to include proton therapy. Out-of-field doses, which are the doses received by regions outside of the treatment field, are unavoidable regardless of the treatment modalities used during radiotherapy. In the case of pregnant patients, fetal dose is a major concern as it has long been recognized that fetuses exposed to radiation have a higher probability of suffering from adverse effects such as anatomical malformations and even fetal death, especially when the 0.1Gy threshold is exceeded. In spite of the low occurrence of cancer during pregnancy, the radiotherapy team should be equipped with the necessary knowledge to deal with fetal dose. This is crucial so as to ensure that the fetus is adequately protected while not compromising the patient treatment outcomes. In this review paper, various aspects of fetal dose will be discussed ranging from biological, clinical to the physics aspects. Other than fetal dose resulting from conventional photon therapy, this paper will also extend the discussion to modern treatment modalities and techniques, namely proton therapy and image-guided radiotherapy, all of which have seen a significant increase in use in current radiotherapy. This review is expected to provide readers with a comprehensive understanding of fetal dose in radiotherapy, and to be fully aware of the steps to be taken in providing radiotherapy for pregnant patients.
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Affiliation(s)
- Yun Ming Wong
- Division of Physics and Applied Physics, Nanyang Technological University, Singapore
| | | | - Kah Seng Lew
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore
| | | | - Wenlong Nei
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore
| | - Hong Qi Tan
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore.
| | - James Cheow Lei Lee
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore; Division of Physics and Applied Physics, Nanyang Technological University, Singapore
| | - Michael Mazonakis
- Department of Medical Physics, School of Medicine, University of Crete, Greece
| | - John Damilakis
- Department of Medical Physics, School of Medicine, University of Crete, Greece
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Development of a computational pregnant female phantom and calculation of fetal dose during a photon breast radiotherapy. Radiol Oncol 2022; 56:541-551. [PMID: 36259318 PMCID: PMC9784366 DOI: 10.2478/raon-2022-0039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 08/01/2022] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND The incidence of carcinoma during pregnancy is reported to be 1:1000-1:1500 pregnancies with the breast carcinoma being the most commonly diagnosed. Since the fetus is most sensitive to ionizing radiation during the first two trimesters, there are mixed clinical opinions and no uniform guidelines on the use of radiotherapy during pregnancy. Within this study the pregnant female phantom in the second trimester, that can be used for radiotherapy treatment planning (as DICOM data), Monte Carlo simulations (as voxelized geometry) and experimental dosimetry utilizing 3D printing of the molds (as .STL files), was developed. MATERIALS AND METHODS The developed phantom is based on MRI images of a female patient in her 18th week of pregnancy and CT images after childbirth. Phantom was developed in such a manner that a pregnant female was scanned "in vivo" using MRI during pregnancy and CT after childbirth. For the treatment of left breast carcinoma, 3D conformal radiotherapy was used. The voxelized geometry of the phantom was used for Monte Carlo (MC) simulations using Monte Carlo N-Particle transport codeTM 6.2 (MCNP). CONCLUSIONS The modeled photon breast radiotherapy plan, applied to the phantom, indicated that the fetus dose is 59 mGy for 50 Gy prescribed to the breast. The results clearly indicate that only 9.5% of the fetal dose is caused by photons that are generated in the accelerator head through scattering and leakage, but the dominant component is scattered radiation from the patient's body.
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Rabus H, Zankl M, Gómez-Ros JM, Villagrasa C, Eakins J, Huet C, Brkić H, Tanner R. Lessons learnt from the recent EURADOS intercomparisons in computational dosimetry. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2022.106822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Tanner R, Agosteo S, Rabus H. EURADOS working group 6, computational dosimetry, a history of promoting good practice via intercomparisons and training. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2022.106829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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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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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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