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Palmans H, Lourenço A, Medin J, Vatnitsky S, Andreo P. Current best estimates of beam quality correction factors for reference dosimetry of clinical proton beams. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac9172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 09/12/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Objective. To review the currently available data on beam quality correction factors,
k
Q
,
for ionization chambers in clinical proton beams and derive their current best estimates for the updated recommendations of the IAEA TRS-398 Code of Practice. Approach. The reviewed data come from 20 publications from which
k
Q
values can be derived either directly from calorimeter measurements, indirectly from comparison with other chambers or from Monte Carlo calculated overall chamber factors,
f
Q
.
For cylindrical ionization chambers, a distinction is made between data obtained in the centre of a spread-out Bragg peak and those obtained in the plateau region of single-energy fields. For the latter, the effect of depth dose gradients has to be considered. To this end an empirical model for previously published displacement correction factors for single-layer scanned beams was established, while for unmodulated scattered beams experimental data were used. From all the data, chamber factors,
f
Q
,
and chamber perturbation correction factors,
p
Q
,
were then derived and analysed. Main results. The analysis showed that except for the beam quality dependence of the water-to-air mass stopping power ratio and, for cylindrical ionization chambers in unmodulated beams, of the displacement correction factor, there is no remaining beam quality dependence of the chamber perturbation correction factors
p
Q
.
Based on this approach, average values of the beam quality independent part of the perturbation factors were derived to calculate
k
Q
values consistent with the data in the literature. Significance. The resulting data from this analysis are current best estimates of
k
Q
values for modulated scattered beams and single-layer scanned beams used in proton therapy. Based on this, a single set of harmonized values is derived to be recommended in the update of IAEA TRS-398.
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2
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Garty G, Harken A, Brenner D. Traceable dosimetry for MeV ion beams. JOURNAL OF INSTRUMENTATION : AN IOP AND SISSA JOURNAL 2022; 17:T02002. [PMID: 35497570 PMCID: PMC9052763 DOI: 10.1088/1748-0221/17/02/t02002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Standard dosimetry protocols exist for highly penetrating photon and particle beams used in the clinic and in research. However, these protocols cannot be directly applied to shallow penetration MeV-range ion beams. The Radiological Research Accelerator Facility has been using such beams for almost 50 years to irradiate cell monolayers, using self-developed dosimetry, based on tissue equivalent ionization chambers. To better align with the internationally accepted standards, we describe implementation of a commercial, NIST-traceable, air-filled ionization chamber for measurement of absorbed dose to water from low energy ions, using radiation quality correction factors calculated using TRS-398 recommendations. The reported dose does not depend on the ionization density in the range of 10-150 keV/μm.
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Affiliation(s)
- G. Garty
- Radiological Research Accelerator Facility, Columbia University, 136 S. Broadway, Irvington, NY 10533, U.S.A
| | - A.D. Harken
- Radiological Research Accelerator Facility, Columbia University, 136 S. Broadway, Irvington, NY 10533, U.S.A
| | - D.J. Brenner
- Radiological Research Accelerator Facility, Columbia University, 136 S. Broadway, Irvington, NY 10533, U.S.A
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Bolsa-Ferruz M, Palmans H, Boersma D, Stock M, Grevillot L. Monte Carlo computation of 3D distributions of stopping power ratios in light ion beam therapy using GATE-RTion. Med Phys 2021; 48:2580-2591. [PMID: 33465819 DOI: 10.1002/mp.14726] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 12/11/2020] [Accepted: 12/20/2020] [Indexed: 12/18/2022] Open
Abstract
PURPOSE This paper presents a novel method for the calculation of three-dimensional (3D) Bragg-Gray water-to-detector stopping power ratio (sw,det ) distributions for proton and carbon ion beams. METHODS Contrary to previously published fluence-based calculations of the stopping power ratio, the sw,det calculation method used in this work is based on the specific way GATE/Geant4 scores the energy deposition. It only requires the use of the so-called DoseActor, as available in GATE, for the calculation of the sw,det at any point of a 3D dose distribution. The simulations are performed using GATE-RTion v1.0, a dedicated GATE release that was validated for the clinical use in light ion beam therapy. RESULTS The Bragg-Gray water-to-air stopping power ratio (sw,air ) was calculated for monoenergetic proton and carbon ion beams with the default stopping power data in GATE-RTion v1.0 and the new ICRU90 recommendation. The sw,air differences between the use of the default and the ICRU90 configuration were 0.6% and 5.4% at the physical range (R80 - 80% dose level in the distal dose fall-off) for a 70 MeV proton beam and a 120 MeV/u carbon ion beam, respectively. For protons, the sw,det results for lithium fluoride, silicon, gadolinium oxysulfide, and the active layer material of EBT2 (radiochromic film) were compared with the literature and a reasonable agreement was found. For a real patient treatment plan, the 3D distributions of sw,det in proton beams were calculated. CONCLUSIONS Our method was validated by comparison with available literature data. Its equivalence with Bragg-Gray cavity theory was demonstrated mathematically. The capability of GATE-RTion v1.0 for the sw,det calculation at any point of a 3D dose distribution for simple and complex proton and carbon ion plans was presented.
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Affiliation(s)
- Marta Bolsa-Ferruz
- MedAustron Ion Therapy Center, Marie Curie-Straße 5, Wiener Neustadt, A-2700, Austria
| | - Hugo Palmans
- MedAustron Ion Therapy Center, Marie Curie-Straße 5, Wiener Neustadt, A-2700, Austria.,Medical Radiation Science, National Physical Laboratory, Teddington, TW11 0LW, UK
| | - David Boersma
- MedAustron Ion Therapy Center, Marie Curie-Straße 5, Wiener Neustadt, A-2700, Austria.,ACMIT Gmbh, Viktor-Kaplan-Straße 2/1, Wiener Neustadt, A-2700, Austria
| | - Markus Stock
- MedAustron Ion Therapy Center, Marie Curie-Straße 5, Wiener Neustadt, A-2700, Austria
| | - Loïc Grevillot
- MedAustron Ion Therapy Center, Marie Curie-Straße 5, Wiener Neustadt, A-2700, Austria
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Zink K. Twenty years after – das neue Dosimetrieprotokoll IAEA TRS-398 am Horizont sichtbar! Z Med Phys 2020; 30:249-251. [PMID: 33127206 DOI: 10.1016/j.zemedi.2020.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Proton transport modeling in a realistic biological environment by using TILDA-V. Sci Rep 2019; 9:14030. [PMID: 31575875 PMCID: PMC6773879 DOI: 10.1038/s41598-019-50270-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 09/05/2019] [Indexed: 12/17/2022] Open
Abstract
Whether it is in radiobiology to identify DNA lesions or in medicine to adapt the radiotherapeutic protocols, a detailed understanding of the radiation-induced interactions in living matter is required. Monte Carlo track-structure codes have been successfully developed to describe these interactions and predict the radiation-induced energy deposits at the nanoscale level in the medium of interest. In this work, the quantum-mechanically based Monte Carlo track-structure code TILDA-V has been used to compute the slowing-down of protons in water and DNA. Stopping power and range are then reported and compared with existing data. Then, a first application of TILDA-V to cellular irradiations is also reported in order to highlight the absolute necessity of taking into account a realistic description of the cellular environment in microdosimetry.
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Lourenço A, Bouchard H, Galer S, Royle G, Palmans H. The influence of nuclear interactions on ionization chamber perturbation factors in proton beams: FLUKA simulations supported by a Fano test. Med Phys 2018; 46:885-891. [DOI: 10.1002/mp.13281] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 10/16/2018] [Accepted: 10/21/2018] [Indexed: 11/05/2022] Open
Affiliation(s)
- Ana Lourenço
- Medical Radiation Science National Physical Laboratory Teddington TW11 0LW UK
- Department of Medical Physics and Biomedical Engineering University College London London WC1E 6BT UK
| | - Hugo Bouchard
- Département de Physique Université de Montréal, Québec 2900 Boulevard Edouard‐Montpetit Montréal QC H3T 1J4 Canada
| | - Sebastian Galer
- Medical Radiation Science National Physical Laboratory Teddington TW11 0LW UK
| | - Gary Royle
- Department of Medical Physics and Biomedical Engineering University College London London WC1E 6BT UK
| | - Hugo Palmans
- Medical Radiation Science National Physical Laboratory Teddington TW11 0LW UK
- Medical Physics Group EBG MedAustron GmbH A‐2700 Wiener Neustadt Austria
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7
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Giordanengo S, Palmans H. Dose detectors, sensors, and their applications. Med Phys 2018; 45:e1051-e1072. [DOI: 10.1002/mp.13089] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 06/19/2018] [Accepted: 06/21/2018] [Indexed: 12/20/2022] Open
Affiliation(s)
- Simona Giordanengo
- Istituto Nazionale di Fisica Nucleare, Section of Torino Via Giuria 1 10125 Torino Italy
| | - Hugo Palmans
- National Physical Laboratory Medical Radiation Science Hampton Road Teddington Middlesex TW11 0LW UK
- EBG MedAustron GmbH Marie‐Curiestraße 5 A‐2700 Wiener Neustadt Austria
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de Vera P, Abril I, Garcia-Molina R. Energy Spectra of Protons and Generated Secondary Electrons around the Bragg Peak in Materials of Interest in Proton Therapy. Radiat Res 2018; 190:282-297. [PMID: 29995591 DOI: 10.1667/rr14988.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The number and energy of secondary electrons generated around the trajectories of swift protons interacting with biological materials are highly relevant in proton therapy, due to the prominent role of low-energy electrons in the production of biodamage. For a given material, electron energy distributions are determined by the proton energy; and it is imperative that the distribution of proton energy at depths around the Bragg peak region be described as accurately as possible. With this objective, we simulated the energy distributions of proton beams of clinically relevant energies (50-300 MeV) at depths around the Bragg peak in liquid water and the water-equivalent polymer poly(methyl methacrylate) (PMMA). By using a simple model, this simulation has been conveniently extended to account for nuclear fragmentation reactions, providing depth-dose curves in excellent agreement with available experimental data. Special care has been taken to describe the electronic excitation spectrum of the target, taking into account its condensed phase nature. A predictive formula has been obtained for the mean value and the width of the proton energy distribution at the Bragg peak depth, quantities which are found to grow linearly with the initial energy of the beam, in good agreement with available data. To accurately characterize (in number and energy) the electrons generated around the proton paths, the energy distributions of the latter at each depth have been convoluted with the energy-dependent ionization inverse mean free paths. This results in a number of low-energy electrons around the Bragg peak larger than when only the proton beam average energy at the given depths is considered. The convoluted ionization inverse mean free path closely resembles the Bragg curve shape. The average energy of the secondary electrons is nearly constant (∼55 eV for liquid water and ∼43 eV for PMMA) in the plateau of the Bragg curve, independent of the proton incident energy and suddenly decaying once the Bragg peak is reached. These findings highlight the importance of a precise calculation of the proton beam energy distribution as a function of the target depth to reliably characterize the secondary electrons generated around the Bragg peak region.
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Affiliation(s)
- Pablo de Vera
- a Departamento de Física - Centro de Investigación en Óptica y Nanofísica, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, E-30100 Murcia, Spain
| | - Isabel Abril
- b Departament de Física Aplicada, Universitat d'Alacant, E-03080 Alacant, Spain
| | - Rafael Garcia-Molina
- a Departamento de Física - Centro de Investigación en Óptica y Nanofísica, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, E-30100 Murcia, Spain
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Wulff J, Baumann KS, Verbeek N, Bäumer C, Timmermann B, Zink K. TOPAS/Geant4 configuration for ionization chamber calculations in proton beams. ACTA ACUST UNITED AC 2018; 63:115013. [DOI: 10.1088/1361-6560/aac30e] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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10
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Chang W, Koba Y, Katayose T, Yasui K, Omachi C, Hariu M, Saitoh H. Correction of stopping power and LET quenching for radiophotoluminescent glass dosimetry in a therapeutic proton beam. Phys Med Biol 2017; 62:8869-8881. [PMID: 28980978 DOI: 10.1088/1361-6560/aa9155] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
To measure the absorbed dose to water D w in proton beams using a radiophotoluminescent glass dosimeter (RGD), a method with the correction for the change of the mass stopping power ratio (SPR) and the linear energy transfer (LET) dependence of radiophotoluminescent efficiency [Formula: see text] is proposed. The calibration coefficient in terms of D w for RGDs (GD-302M, Asahi Techno Glass) was obtained using a 60Co γ-ray. The SPR of water to the RGD was calculated by Monte Carlo simulation, and [Formula: see text] was investigated experimentally using a 70 MeV proton beam. For clinical usage, the residual range R res was used as a quality index to determine the correction factor for the beam quality [Formula: see text] and the LET quenching effect of the RGD [Formula: see text]. The proposed method was evaluated by measuring D w at different depths in a 200 MeV proton beam. For both non-modulated and modulated proton beams, [Formula: see text] decreases rapidly where R res is less than 4 cm. The difference in [Formula: see text] between a non-modulated and a modulated proton beam is less than 0.5% for the R res range from 0 cm to 22 cm. [Formula: see text] decreases rapidly at a LET range from 1 to 2 keV µm-1. In the evaluation experiments, D w using RGDs, [Formula: see text] showed good agreement with that obtained using an ionization chamber and the relative difference was within 3% where R res was larger than 1 cm. The uncertainty budget for [Formula: see text] in a proton beam was estimated to investigate the potential of RGD postal dosimetry in proton therapy. These results demonstrate the feasibility of RGD dosimetry in a therapeutic proton beam and the general versatility of the proposed method. In conclusion, the proposed methodology for RGDs in proton dosimetry is applicable where R res > 1 cm and the RGD is feasible as a postal audit dosimeter for proton therapy.
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Affiliation(s)
- Weishan Chang
- Tokyo Metropolitan University, 7-2-10 Higashi-Ogu, Arakawa-ku, Tokyo 116-8551, Japan. National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555, Japan
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11
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Sorriaux J, Testa M, Paganetti H, Bertrand D, Lee JA, Palmans H, Vynckier S, Sterpin E. Consistency in quality correction factors for ionization chamber dosimetry in scanned proton beam therapy. Med Phys 2017; 44:4919-4927. [DOI: 10.1002/mp.12434] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 05/22/2017] [Accepted: 06/08/2017] [Indexed: 11/09/2022] Open
Affiliation(s)
- Jefferson Sorriaux
- Center of Molecular Imaging, Radiotherapy and Oncology; Institut de Recherche Expérimentale et Clinique; Université catholique de Louvain; Avenue Hippocrate 54 1200 Brussels Belgium
- ICTEAM Institute; Université catholique de Louvain; Chemin du Cyclotron 6 1348 Louvain-la-Neuve Belgium
| | - Mauro Testa
- Department of Radiation Convergence Engineering; Yonsei University; Wonju 220-710 Korea
| | - Harald Paganetti
- Department of Radiation Oncology; Massachusetts General Hospital; Harvard Medical School; Boston MA 02114 USA
| | - Damien Bertrand
- Ion Beam Applications S.A; Chemin du Cyclotron 3 1348 Louvain-la-Neuve Belgium
| | - John Aldo Lee
- Center of Molecular Imaging, Radiotherapy and Oncology; Institut de Recherche Expérimentale et Clinique; Université catholique de Louvain; Avenue Hippocrate 54 1200 Brussels Belgium
- ICTEAM Institute; Université catholique de Louvain; Chemin du Cyclotron 6 1348 Louvain-la-Neuve Belgium
| | - Hugo Palmans
- Medical Physics Department; EBG MedAustron GmbH; Wiener Neustadt A-2700 Austria
- Acoustics and Ionising Radiation Division; National Physical Laboratory; Teddington TW11 OLW UK
| | - Stefaan Vynckier
- Département de Radiothérapie; Cliniques Universitaires Saint-Luc; Avenue Hippocrate 54 1200 Brussels Belgium
| | - Edmond Sterpin
- Center of Molecular Imaging, Radiotherapy and Oncology; Institut de Recherche Expérimentale et Clinique; Université catholique de Louvain; Avenue Hippocrate 54 1200 Brussels Belgium
- Department of Oncology; Laboratory of Experimental Radiotherapy; Katholieke Universiteit Leuven; O&N Herestraat 49 - box 818 3000 Leuven Belgium
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12
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Martinetti F, Donadille L, Delacroix S, Nauraye C, De Oliveira A, Herault J, Clairand I. Monte Carlo Modeling of a Protontherapy Beam Line Dedicated to Ophthalmologic Treatments. NUCL TECHNOL 2017. [DOI: 10.13182/nt09-a9296] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Florent Martinetti
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), BP 17, 92262 Fontenay aux Roses Cedex, France
| | - Laurent Donadille
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), BP 17, 92262 Fontenay aux Roses Cedex, France
| | - Sabine Delacroix
- Institut Curie-Centre de Protonthérapie d’Orsay (ICPO), Campus universitaire bâtiment 101, 91898 Orsay, France
| | - Catherine Nauraye
- Institut Curie-Centre de Protonthérapie d’Orsay (ICPO), Campus universitaire bâtiment 101, 91898 Orsay, France
| | - Aurélien De Oliveira
- Institut Curie-Centre de Protonthérapie d’Orsay (ICPO), Campus universitaire bâtiment 101, 91898 Orsay, France
| | - Joël Herault
- Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice Cedex 2, France
| | - Isabelle Clairand
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), BP 17, 92262 Fontenay aux Roses Cedex, France
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Durante M, Paganetti H. Nuclear physics in particle therapy: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:096702. [PMID: 27540827 DOI: 10.1088/0034-4885/79/9/096702] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Charged particle therapy has been largely driven and influenced by nuclear physics. The increase in energy deposition density along the ion path in the body allows reducing the dose to normal tissues during radiotherapy compared to photons. Clinical results of particle therapy support the physical rationale for this treatment, but the method remains controversial because of the high cost and of the lack of comparative clinical trials proving the benefit compared to x-rays. Research in applied nuclear physics, including nuclear interactions, dosimetry, image guidance, range verification, novel accelerators and beam delivery technologies, can significantly improve the clinical outcome in particle therapy. Measurements of fragmentation cross-sections, including those for the production of positron-emitting fragments, and attenuation curves are needed for tuning Monte Carlo codes, whose use in clinical environments is rapidly increasing thanks to fast calculation methods. Existing cross sections and codes are indeed not very accurate in the energy and target regions of interest for particle therapy. These measurements are especially urgent for new ions to be used in therapy, such as helium. Furthermore, nuclear physics hardware developments are frequently finding applications in ion therapy due to similar requirements concerning sensors and real-time data processing. In this review we will briefly describe the physics bases, and concentrate on the open issues.
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Affiliation(s)
- Marco Durante
- Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute of Nuclear Physics (INFN), University of Trento, Via Sommarive 14, 38123 Povo (TN), Italy. Department of Physics, University Federico II, Naples, Italy
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15
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Gomà C, Andreo P, Sempau J. Monte Carlo calculation of beam quality correction factors in proton beams using detailed simulation of ionization chambers. Phys Med Biol 2016; 61:2389-406. [DOI: 10.1088/0031-9155/61/6/2389] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
The physics of proton therapy has advanced considerably since it was proposed in 1946. Today analytical equations and numerical simulation methods are available to predict and characterize many aspects of proton therapy. This article reviews the basic aspects of the physics of proton therapy, including proton interaction mechanisms, proton transport calculations, the determination of dose from therapeutic and stray radiations, and shielding design. The article discusses underlying processes as well as selected practical experimental and theoretical methods. We conclude by briefly speculating on possible future areas of research of relevance to the physics of proton therapy.
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Affiliation(s)
- Wayne D Newhauser
- Medical Physics Program, Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, LA, 70803, USA
- Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA, 70809, USA
| | - Rui Zhang
- Medical Physics Program, Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, LA, 70803, USA
- Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA, 70809, USA
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Gomà C, Hofstetter-Boillat B, Safai S, Vörös S. Experimental validation of beam quality correction factors for proton beams. Phys Med Biol 2015; 60:3207-16. [DOI: 10.1088/0031-9155/60/8/3207] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Mali SB. Proton therapy for head neck cancer. Oral Oncol 2014; 51:e10-2. [PMID: 25467208 DOI: 10.1016/j.oraloncology.2014.10.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 10/21/2014] [Accepted: 10/23/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Shrikant Balasaheb Mali
- MGV KBH Dental College Nashik, Flat no 2, Jyoti Savitri Apartment, Above Bank of Maharashtra, Ashoka Marg, Nashik, India.
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Abstract
The first goal of this paper is to clarify the reference conditions for the reference dosimetry of clinical proton beams. A clear distinction is made between proton beam delivery systems which should be calibrated with a spread-out Bragg peak field and those that should be calibrated with a (pseudo-)monoenergetic proton beam. For the latter, this paper also compares two independent dosimetry techniques to calibrate the beam monitor chambers: absolute dosimetry (of the number of protons exiting the nozzle) with a Faraday cup and reference dosimetry (i.e. determination of the absorbed dose to water under IAEA TRS-398 reference conditions) with an ionization chamber. To compare the two techniques, Monte Carlo simulations were performed to convert dose-to-water to proton fluence. A good agreement was found between the Faraday cup technique and the reference dosimetry with a plane-parallel ionization chamber. The differences-of the order of 3%-were found to be within the uncertainty of the comparison. For cylindrical ionization chambers, however, the agreement was only possible when positioning the effective point of measurement of the chamber at the reference measurement depth-i.e. not complying with IAEA TRS-398 recommendations. In conclusion, for cylindrical ionization chambers, IAEA TRS-398 reference conditions for monoenergetic proton beams led to a systematic error in the determination of the absorbed dose to water, especially relevant for low-energy proton beams. To overcome this problem, the effective point of measurement of cylindrical ionization chambers should be taken into account when positioning the reference point of the chamber. Within the current IAEA TRS-398 recommendations, it seems advisable to use plane-parallel ionization chambers-rather than cylindrical chambers-for the reference dosimetry of pseudo-monoenergetic proton beams.
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Affiliation(s)
- C Gomà
- Centre for Proton Therapy, Paul Scherrer Institute, Villigen PSI, Switzerland. Department of Physics, Swiss Federal Institute of Technology Zurich, Zurich, Switzerland
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de Vera P, Abril I, Garcia-Molina R. Water equivalent properties of materials commonly used in proton dosimetry. Appl Radiat Isot 2014; 83 Pt B:122-7. [PMID: 23478093 DOI: 10.1016/j.apradiso.2013.01.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 01/10/2013] [Accepted: 01/11/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Pablo de Vera
- Departament de Física Aplicada, Universitat d'Alacant, E-03080 Alacant, Spain
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Andreo P, Wulff J, Burns DT, Palmans H. Consistency in reference radiotherapy dosimetry: resolution of an apparent conundrum when60Co is the reference quality for charged-particle and photon beams. Phys Med Biol 2013; 58:6593-621. [DOI: 10.1088/0031-9155/58/19/6593] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Palmans H, Al-Sulaiti L, Andreo P, Shipley D, Lühr A, Bassler N, Martinkovič J, Dobrovodský J, Rossomme S, Thomas RAS, Kacperek A. Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations. Phys Med Biol 2013; 58:3481-99. [DOI: 10.1088/0031-9155/58/10/3481] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Gomà C, Andreo P, Sempau J. Spencer–Attix water/medium stopping-power ratios for the dosimetry of proton pencil beams. Phys Med Biol 2013; 58:2509-22. [DOI: 10.1088/0031-9155/58/8/2509] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Sánchez-Parcerisa D, Gemmel A, Jäkel O, Rietzel E, Parodi K. Influence of the delta ray production threshold on water-to-air stopping power ratio calculations for carbon ion beam radiotherapy. Phys Med Biol 2012; 58:145-58. [DOI: 10.1088/0031-9155/58/1/145] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Wang LLW, Perles LA, Archambault L, Sahoo N, Mirkovic D, Beddar S. Determination of the quenching correction factors for plastic scintillation detectors in therapeutic high-energy proton beams. Phys Med Biol 2012; 57:7767-81. [PMID: 23128412 DOI: 10.1088/0031-9155/57/23/7767] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Plastic scintillation detectors (PSDs) have many advantages over other detectors in small field dosimetry due to their high spatial resolution, excellent water equivalence and instantaneous readout. However, in proton beams, the PSDs undergo a quenching effect which makes the signal level reduced significantly when the detector is close to the Bragg peak where the linear energy transfer (LET) for protons is very high. This study measures the quenching correction factor (QCF) for a PSD in clinical passive-scattering proton beams and investigates the feasibility of using PSDs in depth-dose measurements in proton beams. A polystyrene-based PSD (BCF-12, ϕ0.5 mm × 4 mm) was used to measure the depth-dose curves in a water phantom for monoenergetic unmodulated proton beams of nominal energies 100, 180 and 250 MeV. A Markus plane-parallel ion chamber was also used to get the dose distributions for the same proton beams. From these results, the QCF as a function of depth was derived for these proton beams. Next, the LET depth distributions for these proton beams were calculated by using the MCNPX Monte Carlo code, based on the experimentally validated nozzle models for these passive-scattering proton beams. Then the relationship between the QCF and the proton LET could be derived as an empirical formula. Finally, the obtained empirical formula was applied to the PSD measurements to get the corrected depth-dose curves and they were compared to the ion chamber measurements. A linear relationship between the QCF and LET, i.e. Birks' formula, was obtained for the proton beams studied. The result is in agreement with the literature. The PSD measurements after the quenching corrections agree with ion chamber measurements within 5%. PSDs are good dosimeters for proton beam measurement if the quenching effect is corrected appropriately.
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Affiliation(s)
- L L W Wang
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Gorjiara T, Kuncic Z, Doran S, Adamovics J, Baldock C. Water and tissue equivalence of a new PRESAGE® formulation for 3D proton beam dosimetry: A Monte Carlo study. Med Phys 2012; 39:7071-9. [DOI: 10.1118/1.4757922] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Moskvin V, Cheng CW, Fanelli L, Zhao L, Das IJ. A semi-empirical model for the therapeutic range shift estimation caused by inhomogeneities in proton beam therapy. J Appl Clin Med Phys 2012; 13:3631. [PMID: 22402381 PMCID: PMC5716409 DOI: 10.1120/jacmp.v13i2.3631] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 06/28/2011] [Accepted: 10/16/2011] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to devise a simple semi‐empirical model to estimate the range shift in clinical practices with high‐Z inhomogeneity in proton beam. A semi‐empirical model utilizing the logarithmic dependence on Z in stopping power from Bohr's classical approach has been developed to calculate the range shift due to the presence of inhomogeneity. Range shift from metallic plates of atomic number Z of various thicknesses were measured in water using a parallel plate ionization chamber and calculated with the FLUKA Monte Carlo code. The proton range shifts for bone and polymethyl methacrylate (PMMA) were estimated using the semi‐empirical model and compared with Monte Carlo calculation. The semi‐empirical equation to determine range shift and water equivalent thickness is presented. The model predicts a shift of the therapeutic range to within 2.5% accuracy for initial proton energies of 50 to 250 MeV and atomic numbers from 3.3 (effective Z for water) to 82. This equation is independent of beam energy, and thus provides range shift from high‐Z materials without the knowledge of proton energy. The proposed method of calculating the therapeutic range shift accurately requires only knowledge of the effective or actual atomic number of the inhomogeneity and the thickness of the inhomogeneity along the beam direction. The model generalizes the range shift calculation for any material based on its effective atomic number, and permits reliable prediction of the range shift for material combinations where no data is currently available. The proposed model can be readily implemented in routine clinical practice for proton range shift estimation and quality assurance on the treatment planning. PACS numbers: 87.53.‐j, 87.55.‐x, 87.53.Bn, 87.55.D‐, 87.55.Qr, 87.55.K‐
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Affiliation(s)
- Vadim Moskvin
- Department of Radiation Oncology, Indiana University School of Medicine, 535 Barnhill Dr. RT-041, Indianapolis, IN 46202, USA.
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Lühr A, Hansen DC, Sobolevsky N, Palmans H, Rossomme S, Bassler N. Fluence correction factors and stopping power ratios for clinical ion beams. Acta Oncol 2011; 50:797-805. [PMID: 21767177 DOI: 10.3109/0284186x.2011.581691] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND In radiation therapy, the principal dosimetric quantity of interest is the absorbed dose to water. Therefore, a dose conversion to dose to water is required for dose deposited by ion beams in other media. This is in particular necessary for dose measurements in plastic phantoms for increased positioning accuracy, graphite calorimetry being developed as a primary standard for dose to water dosimetry, but also for the comparison of dose distributions from Monte Carlo simulations with those of pencil beam algorithms. MATERIAL AND METHODS In the conversion of absorbed dose to phantom material to absorbed dose to water the water-to-material stopping power ratios (STPR) and the fluence correction factors (FCF) for the full charged particle spectra are needed. We determined STPR as well as FCF for water to graphite, bone (compact), and PMMA as a function of water equivalent depth, z(w), with the Monte Carlo code SHIELD-HIT10A. Simulations considering all secondary ions were performed for primary protons as well as carbon, nitrogen and oxygen ions with a total range of 3 cm, 14.5 cm and 27 cm as well as for two spread-out Bragg-peaks (SOBP). STPR as a function of depth are also compared to a recently proposed analytical formula. RESULTS The STPR are of the order of 1.022, 1.070, and 1.112 for PMMA, bone, and graphite, respectively. STPR vary only little with depth except close to the total range of the ion and they can be accurately approximated with an analytical formula. The amplitude of the FCF depends on the non-elastic nuclear interactions and it is unity if these interactions are turned off in the simulation. Fluence corrections are of the order of a percent becoming more pronounced for larger depths resulting in dose difference of the order of 5% around 25 cm. The same order of magnitude is observed for SOBP. CONCLUSIONS We conclude that for ions with small total range (z(w-eq) ≤3 cm) dosimetry without applying FCF could in principle be performed in phantoms of materials other than water without a significant loss of accuracy. However, in clinical high-energy ion beams with penetration depths z(w-eq) ≥3 cm, where accurate positioning in water is not an issue, absorbed dose measurements should be directly performed in water or accurate values of FCF need to be established.
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Affiliation(s)
- Armin Lühr
- Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark.
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Rinaldi I, Ferrari A, Mairani A, Paganetti H, Parodi K, Sala P. An integral test of FLUKA nuclear models with 160 MeV proton beams in multi-layer Faraday cups. Phys Med Biol 2011; 56:4001-11. [PMID: 21677365 DOI: 10.1088/0031-9155/56/13/016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Monte Carlo (MC) codes are useful tools to simulate the complex processes of proton beam interactions with matter. In proton therapy, nuclear reactions influence the dose distribution. Therefore, the validation of nuclear models adopted in MC codes is a critical requisite for their use in this field. A simple integral test can be performed using a multi-layer Faraday cup (MLFC). This method allows separation of the nuclear and atomic interaction processes, which are responsible for secondary particle emission and the finite primary proton range, respectively. In this work, the propagation of 160 MeV protons stopping in two MLFCs made of polyethylene and copper has been simulated by the FLUKA MC code. The calculations have been performed with and without secondary electron emission and transport, as well as charge sharing in the dielectric layers. Previous results with other codes neglected those two effects. The impact of this approximation has been investigated and found to be relevant only in the proximity of the Bragg peak. Longitudinal charge distributions computed with FLUKA with both approaches have been compared with experimental data from the literature. Moreover, the contribution of different processes to the measurable signal has been addressed. A thorough analysis of the results has demonstrated that the nuclear and electromagnetic models of FLUKA reproduce the two sets of experimental data reasonably well.
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Affiliation(s)
- I Rinaldi
- German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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Ulmer W, Schaffner B. Foundation of an analytical proton beamlet model for inclusion in a general proton dose calculation system. Radiat Phys Chem Oxf Engl 1993 2011. [DOI: 10.1016/j.radphyschem.2010.10.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Athar BS, Paganetti H. Comparison of second cancer risk due to out-of-field doses from 6-MV IMRT and proton therapy based on 6 pediatric patient treatment plans. Radiother Oncol 2010; 98:87-92. [PMID: 21159398 DOI: 10.1016/j.radonc.2010.11.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 11/10/2010] [Accepted: 11/14/2010] [Indexed: 01/17/2023]
Abstract
BACKGROUND AND PURPOSE This study compared 6-MV IMRT and proton therapy in terms of organ specific second cancer lifetime attributable risks (LARs) caused by scattered and secondary out-of-field radiation. MATERIALS AND METHODS Based on simulated organ doses, excess relative and excess absolute risk models were applied to assess organ-specific LARs. Two treatment sites (cranium and central spine) were considered involving six treatment volumes and six patient ages (9-month, 4-year, 8-year, 11-year, 14-year, and adult). RESULTS The LARs for thyroid cancer from a 6 cm diameter field treating a brain lesion in a 4-year old patient were estimated to be 1.1% and 0.3% in passive proton therapy and IMRT, respectively. However, estimated LARs for bladder cancer, more than 25 cm from the field edge for the same patient and treatment field, were estimated to be 0.2% and 0.02% from IMRT and proton therapy, respectively. Risks for proton beam scanning was found to be an order of magnitude smaller compared to passive proton therapy. CONCLUSION In terms of out-of-field risks, IMRT offers advantage close to the primary field and an increasing advantage for passive proton therapy is noticed with increasing distance to the field. Scanning proton beam therapy shows the lowest risks.
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Affiliation(s)
- Basit S Athar
- Department of Radiation Oncology, Massachusetts General Hospital & Harvard Medical School, MA, USA.
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Abril I, Garcia-Molina R, Denton CD, Kyriakou I, Emfietzoglou D. Energy loss of hydrogen- and helium-ion beams in DNA: calculations based on a realistic energy-loss function of the target. Radiat Res 2010; 175:247-55. [PMID: 21268719 DOI: 10.1667/rr2142.1] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We have calculated the electronic energy loss of proton and α-particle beams in dry DNA using the dielectric formalism. The electronic response of DNA is described by the MELF-GOS model, in which the outer electron excitations of the target are accounted for by a linear combination of Mermin-type energy-loss functions that accurately matches the available experimental data for DNA obtained from optical measurements, whereas the inner-shell electron excitations are modeled by the generalized oscillator strengths of the constituent atoms. Using this procedure we have calculated the stopping power and the energy-loss straggling of DNA for hydrogen- and helium-ion beams at incident energies ranging from 10 keV/nucleon to 10 MeV/nucleon. The mean excitation energy of dry DNA is found to be I = 81.5 eV. Our present results are compared with available calculations for liquid water showing noticeable differences between these important biological materials. We have also evaluated the electron excitation probability of DNA as a function of the transferred energy by the swift projectile as well as the average energy of the target electronic excitations as a function of the projectile energy. Our results show that projectiles with energy ≲100 keV/nucleon (i.e., around the stopping-power maximum) are more suitable for producing low-energy secondary electrons in DNA, which could be very effective for the biological damage of malignant cells.
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Affiliation(s)
- Isabel Abril
- Departament de Física Aplicada, Universitat d'Alacant, Alacant, Spain
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Abstract
Recently, ion beam radiotherapy (including protons as well as heavier ions) gained considerable interest. Although ion beam radiotherapy requires dose prescription in terms of iso-effective dose (referring to an iso-effective photon dose), absorbed dose is still required as an operative quantity to control beam delivery, to characterize the beam dosimetrically and to verify dose delivery. This paper reviews current methods and standards to determine absorbed dose to water in ion beam radiotherapy, including (i) the detectors used to measure absorbed dose, (ii) dosimetry under reference conditions and (iii) dosimetry under non-reference conditions. Due to the LET dependence of the response of films and solid-state detectors, dosimetric measurements are mostly based on ion chambers. While a primary standard for ion beam radiotherapy still remains to be established, ion chamber dosimetry under reference conditions is based on similar protocols as for photons and electrons although the involved uncertainty is larger than for photon beams. For non-reference conditions, dose measurements in tissue-equivalent materials may also be necessary. Regarding the atomic numbers of the composites of tissue-equivalent phantoms, special requirements have to be fulfilled for ion beams. Methods for calibrating the beam monitor depend on whether passive or active beam delivery techniques are used. QA measurements are comparable to conventional radiotherapy; however, dose verification is usually single field rather than treatment plan based. Dose verification for active beam delivery techniques requires the use of multi-channel dosimetry systems to check the compliance of measured and calculated dose for a representative sample of measurement points. Although methods for ion beam dosimetry have been established, there is still room for developments. This includes improvement of the dosimetric accuracy as well as development of more efficient measurement techniques.
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Affiliation(s)
- Christian P Karger
- Department of Medical Physics in Radiation Oncology (E040), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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36
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Kirby D, Green S, Palmans H, Hugtenburg R, Wojnecki C, Parker D. LET dependence of GafChromic films and an ion chamber in low-energy proton dosimetry. Phys Med Biol 2009; 55:417-33. [DOI: 10.1088/0031-9155/55/2/006] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Neutrons from the reactions of protons or deuterons of energies between 35 and 70 MeV on beryllium are most suitable for therapy because of the high yield and good penetration. Lower energy sources are used for limited applications. Proton therapy is conducted mainly in two energy ranges, viz. 60–75 MeV (exclusively for the treatment of eye lesions) and ≥200 MeV for general applications. Characterisation of both neutron and proton therapy beams in terms of spectral fluence is important for accurate determination of dosimetry parameters, for interpreting biological effects, for intercomparison purposes and to perform accurate radiation transport calculations.
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Abstract
Dose in radiation therapy is traditionally reported as the water-equivalent dose, or dose to water. Monte Carlo dose calculations report dose to medium and thus a methodology is needed to convert dose to medium into dose to water (or vice versa) for comparison of Monte Carlo results with results from planning systems. This paper describes the development of a formalism to convert dose to medium into dose to water for proton fields when simulating the dose with Monte Carlo techniques. The conversion is based on relative stopping power but also considers energy transferred via nuclear interactions. The influence of different interaction mechanisms of proton beams (electromagnetic versus nuclear) is demonstrated. Further, an approximate method for converting doses retroactively is presented. Based on the outlined formalism, five proton therapy patients with a total of 33 fields were analyzed. Dose distributions, dose volume histograms and absolute doses to assess the clinical significance of differences between dose to medium and dose to water are presented. We found that the difference between the two dose reporting definitions can be up to 10% for high CT numbers if analyzing the mean dose to the target. The difference is clinically insignificant for soft tissues. For the structures analyzed, the mean dose to water could be converted to dose to medium by applying a correction factor increasing linearly with increasing average CT number in the volume. We determined that an approximate conversion method, done retroactively with an energy-independent stopping power ratio and without considering nuclear interaction events separately (as compared to on-the-fly conversion during simulation), is sufficiently accurate to compute mean doses. It is insufficient, however, when analyzing the beam range. For proton beams stopping in bony anatomy, the predicted beam range can differ by 2-3 mm when comparing dose to tissue and dose to water.
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Affiliation(s)
- Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital & Harvard Medical School, Boston, MA 02114, USA.
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Paganetti H, Jiang H, Parodi K, Slopsema R, Engelsman M. Clinical implementation of full Monte Carlo dose calculation in proton beam therapy. Phys Med Biol 2008; 53:4825-53. [PMID: 18701772 DOI: 10.1088/0031-9155/53/17/023] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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Hollmark M, Gudowska I, Belkić D, Brahme A, Sobolevsky N. An analytical model for light ion pencil beam dose distributions: multiple scattering of primary and secondary ions. Phys Med Biol 2008; 53:3477-91. [DOI: 10.1088/0031-9155/53/13/005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Newhauser W, Fontenot J, Zheng Y, Polf J, Titt U, Koch N, Zhang X, Mohan R. Monte Carlo simulations for configuring and testing an analytical proton dose-calculation algorithm. Phys Med Biol 2007; 52:4569-84. [PMID: 17634651 DOI: 10.1088/0031-9155/52/15/014] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Contemporary treatment planning systems for proton radiotherapy typically use analytical pencil-beam algorithms - which require a comprehensive set of configuration data - to predict the absorbed dose distributions in the patient. In order to reduce the time required to prepare a new proton treatment planning system for clinical use, it was desirable to configure the planning system before measured beam data were available. However, it was not known if the Monte Carlo simulation method was a practical alternative to measuring beam profiles. The purpose of this study was to develop a model of a passively scattered proton therapy unit, to simulate the properties of the proton fields using the Monte Carlo technique and to configure an analytical treatment planning system using the simulated beam data. Additional simulations and treatment plans were calculated in order to validate the pencil-beam predictions against the Monte Carlo simulations using realistic treatment beams. Comparison of dose distributions in a water phantom revealed small dose difference and distances to agreement under the validation conditions. The total simulation time for generating the 768 beam configuration profiles was approximately 6 weeks using 30 nodes in a parallel processing cluster. The results of this study show that it is possible to configure and test a proton treatment planning system prior to the availability of measured proton beam data. The model presented here provided a means to reduce by several months the time required to prepare an analytical treatment planning system for patient treatments.
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Affiliation(s)
- Wayne Newhauser
- Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
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Seco J, Jiang H, Herrup D, Kooy H, Paganetti H. A Monte Carlo tool for combined photon and proton treatment planning verification. ACTA ACUST UNITED AC 2007. [DOI: 10.1088/1742-6596/74/1/021014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Tuckwell W, Bezak E. Calculation of the positron distribution from 15O nuclei formed in nuclear reactions in human tissue during proton therapy. Phys Med Biol 2007; 52:2483-98. [PMID: 17440247 DOI: 10.1088/0031-9155/52/9/010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
To measure and verify the dose distribution within a patient during proton therapy, indirect methods must be used. One such method is to use positron emission tomography (PET), which takes advantage of the nuclear reactions that take place between protons and nuclei in the tissue. The dominant nuclear reaction in human muscle tissue involves oxygen nuclei and produces radioactive oxygen-15. Oxygen-15 decays through positron emission, and it is these positrons that go on to annihilate that produce the signal used in the PET technique. Finding the distribution of annihilation points, however, is not analogous to finding the proton dose distribution. The oxygen-15 and positrons travel finite distances within the tissue, blurring the detected PET distribution from the desired proton distribution. Through Monte Carlo modelling, an analysis of the differences between the positron, oxygen-15 and proton distributions has been made. The program SRIM 2003 was used to find the correlation between the three distributions within simulated muscle tissue. Results show that the distal edge of the proton Bragg peak correlates with the detectable positron distribution, which is a section of the dose distribution of interest due to the steep dose gradient and position of adjacent critical structures.
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Affiliation(s)
- W Tuckwell
- School of Chemistry and Physics, University of Adelaide, Adelaide, South Australia, Australia.
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Jiang H, Seco J, Paganetti H. Effects of Hounsfield number conversion on CT based proton Monte Carlo dose calculations. Med Phys 2007; 34:1439-49. [PMID: 17500475 PMCID: PMC2292645 DOI: 10.1118/1.2715481] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The Monte Carlo method provides the most accurate dose calculations on a patient computed tomography (CT) geometry. The increase in accuracy is, at least in part, due to the fact that instead of treating human tissues as water of various densities as in analytical algorithms, the Monte Carlo method allows human tissues to be characterized by elemental composition and mass density, and hence allows the accurate consideration of all relevant electromagnetic and nuclear interactions. On the other hand, the algorithm to convert CT Hounsfield numbers to tissue materials for Monte Carlo dose calculation introduces uncertainties. There is not a simple one to one correspondence between Hounsfield numbers and tissue materials. To investigate the effects of Hounsfield number conversion for proton Monte Carlo dose calculations, clinical proton treatment plans were simulated using the Geant4 Monte Carlo code. Three Hounsfield number to material conversion methods were studied. The results were compared in forms of dose volume histograms of gross tumor volume and clinical target volume. The differences found are generally small but can be dosimetrically significant. Further, different methods may cause deviations in the predicted proton beam range in particular for deep proton fields. Typically, slight discrepancies in mass density assignments play only a minor role in the target region, whereas more significant effects are caused by different assignments in elemental compositions. In the presence of large tissue inhomogeneities, for head and neck treatments, treatment planning decisions could be affected by these differences because of deviations in the predicted tumor coverage. Outside the target area, differences in elemental composition and mass density assignments both may play a role. This can lead to pronounced effects for organs at risk, in particular in the spread-out Bragg peak penumbra or distal regions. In addition, the significance of the elemental composition effect (dose to water vs. dose to tissue) is tissue-type dependent and is also affected by nuclear reactions.
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Affiliation(s)
| | - Joao Seco
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
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Kempe J, Gudowska I, Brahme A. Depth absorbed dose and LET distributions of therapeutic H1, He4, Li7, and C12 beams. Med Phys 2006; 34:183-92. [PMID: 17278503 DOI: 10.1118/1.2400621] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The depth absorbed dose and LET (linear energy transfer) distribution of different ions of clinical interest such as 1H, 4He, 7Li, and 12C ions have been investigated using the Monte Carlo code SHIELD-HIT. The energies of the projectiles correspond to ranges in water and soft tissue of approximately 260 mm. The depth dose distributions of the primary particles and their secondaries have been calculated and separated with regard to their low and high LET components. A LET value below 10 eV/nm can generally be regarded as low LET and sparsely ionizing like electrons and photons. The high LET region may be assumed to start at 20 eV/nm where on average two double-strand breaks can be formed when crossing the periphery of a nucleosome, even though strictly speaking the LET limits are not sharp and ought to vary with the charge and mass of the ion. At the Bragg peak of a monoenergetic high energy proton beam, less than 3% of the total absorbed dose is comprised of high LET components above 20 eV/nm. The high LET contribution to the total absorbed dose in the Bragg peak is significantly larger with increasing ion charge as a natural result of higher stopping power and lower range straggling. The fact that the range straggling and multiple scattering are reduced by half from hydrogen to helium increases the possibility to accurately deposit only the high LET component in the tumor with negligible dose to organs at risk. Therefore, the lateral penumbra is significantly improved and the higher dose gradients of 7Li and 12C ions both longitudinally and laterally will be of major advantage in biological optimized radiation therapy. With increasing charge of the ion, the high LET absorbed dose in the beam entrance and the plateau regions where healthy normal tissues are generally located is also increased. The dose distribution of the high LET components in the 7Li beam is only located around the Bragg peak, characterized by a Gaussian-type distribution. Furthermore, the secondary particles produced by high energy 7Li ions in tissuelike media have mainly low LET character both in front of and beyond the Bragg peak.
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Affiliation(s)
- Johanna Kempe
- Division of Medical Radiation Physics, Department of Oncology-Pathology, Karolinska Institutet and Stockholm University, Box 260, SE-171 76 Stockholm, Sweden.
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Medin J, Ross CK, Klassen NV, Palmans H, Grusell E, Grindborg JE. Experimental determination of beam quality factors,kQ, for two types of Farmer chamber in a 10 MV photon and a 175 MeV proton beam. Phys Med Biol 2006; 51:1503-21. [PMID: 16510959 DOI: 10.1088/0031-9155/51/6/010] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Absorbed doses determined with a sealed water calorimeter operated at 4 degrees C are compared with the results obtained using ionization chambers and the IAEA TRS-398 code of practice in a 10 MV photon beam (TPR(20,10) = 0.734) and a 175 MeV proton beam (at a depth corresponding to the residual range, R(res) = 14.7 cm). Three NE 2571 and two FC65-G ionization chambers were calibrated in terms of absorbed-dose-to-water in (60)Co at the Swedish secondary standard dosimetry laboratory, directly traceable to the BIPM. In the photon beam quality, calorimetry was found to agree with ionometry within 0.3%, confirming the k(Q) values tabulated in TRS-398. In contrast, a 1.8% deviation was found in the proton beam at 6 g cm(-2) depth, suggesting that the TRS-398 tabulated k(Q) values for these two ionization chamber types are too high. Assuming no perturbation effect in the proton beam for the ionization chambers, a value for (w(air)/e)(Q) of 33.6 J C(-1) +/- 1.7% (k = 1) can be derived from these measurements. An analytical evaluation of the effect from non-elastic nuclear interactions in the ionization chamber wall indicates a perturbation effect of 0.6%. Including this estimated result in the proton beam would increase the determined (w(air)/e)(Q) value by the same amount.
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Affiliation(s)
- Joakim Medin
- Department of Medical Radiation Physics, Lund University, Malmö University Hospital, SE-205 02 Malmö, Sweden.
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Ohtani H. Charged particle equilibrium of small field in clinical proton beams. Nihon Hoshasen Gijutsu Gakkai Zasshi 2005; 61:1645-50. [PMID: 16395240 DOI: 10.6009/jjrt.kj00004017355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
It is expected that proton beam radiotherapy will become an effective treatment for tumors. For an organ for which a correct dose prescription is required, a proton beam has the ability to provide the dose most suitable for the specific purpose. We measured the charged particle equilibrium factor of proton beams in water using a plane parallel ionization chamber. The maximum energy of the proton beam used in this study was 70 MeV, produced from an isochronous cyclotron. We assume that the charged particle equilibrium factor can be separated into longitudinal and lateral components, that is, the factor E (Z, R) is dependent on depth, Z, and field radius, R; such that E (Z, R) =E (Z) E (R). The E (Z) -factor of primary protons was considered in order to investigate the influence of secondary charged particles. From the results, the charged particle equilibrium factor for the longitudinal component does not remain sharp with the decrease of water depth, and the lateral component is not maintained with the decrease of field size. However, the longitudinal components of primary protons at shallow depth were in equilibrium.
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Affiliation(s)
- Hiroki Ohtani
- Tokyo Metropolitan University, Faculty of Health Sciences, School of Radiologic Science
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49
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Pshenichnov I, Mishustin I, Greiner W. Neutrons from fragmentation of light nuclei in tissue-like media: a study with the GEANT4 toolkit. Phys Med Biol 2005; 50:5493-507. [PMID: 16306647 DOI: 10.1088/0031-9155/50/23/005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We study energy deposition by light nuclei in tissue-like media taking into account nuclear fragmentation reactions, in particular, production of secondary neutrons. The calculations are carried out within a Monte Carlo model for heavy-ion therapy (MCHIT) based on the GEANT4 toolkit. Experimental data on depth-dose distributions for 135-400 A MeV (12)C and (18)O beams are described very well without any adjustment of the model parameters. This gives confidence in successful use of the GEANT4 toolkit for MC simulations of cancer therapy with beams of light nuclei. The energy deposition due to secondary neutrons produced by (12)C and (20)Ne beams in a (40-50 cm)(3) water phantom is estimated to be 1-2% of the total dose, that is only slightly above the neutron contribution (approximately 1%) induced by a 200 MeV proton beam.
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Affiliation(s)
- Igor Pshenichnov
- Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe University, Frankfurt am Main, Germany.
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50
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Newhauser W, Koch N, Hummel S, Ziegler M, Titt U. Monte Carlo simulations of a nozzle for the treatment of ocular tumours with high-energy proton beams. Phys Med Biol 2005; 50:5229-49. [PMID: 16264250 DOI: 10.1088/0031-9155/50/22/002] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
By the end of 2002, 33 398 patients worldwide had been treated with proton radiotherapy, 10 829 for eye diseases. The dose prediction algorithms used today for ocular proton therapy treatment planning rely on parameterizations of measured proton dose distributions, i.e., broad-beam and pencil-beam techniques, whose predictive capabilities are inherently limited by severe approximations and simplifications in modelling the radiation transport physics. In contrast, the Monte Carlo radiation transport technique can, in principle, provide accurate predictions of the proton treatment beams by taking into account all the physical processes involved, including coulombic energy loss, energy straggling, multiple Coulomb scattering, elastic and nonelastic nuclear interactions, and the transport of secondary particles. It has not been shown, however, whether it is possible to commission a proton treatment planning system by using data exclusively from Monte Carlo simulations of the treatment apparatus and a phantom. In this work, we made benchmark comparisons between Monte Carlo predictions and measurements of an ocular proton treatment beamline. The maximum differences between absorbed dose profiles from simulations and measurements were 6% and 0.6 mm, while typical differences were less than 2% and 0.2 mm. The computation time for the entire virtual commissioning process is less than one day. The study revealed that, after a significant development effort, a Monte Carlo model of a proton therapy apparatus is sufficiently accurate and fast for commissioning a treatment planning system.
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Affiliation(s)
- Wayne Newhauser
- The University of Texas M D Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX, USA.
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