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Schafasand M, Resch AF, Nachankar A, Góra J, Martino G, Traneus E, Glimelius L, Georg D, Fossati P, Carlino A, Stock M. Dose averaged linear energy transfer optimization for large sacral chordomas in carbon ion therapy. Med Phys 2024. [PMID: 38696546 DOI: 10.1002/mp.17102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 04/16/2024] [Accepted: 04/17/2024] [Indexed: 05/04/2024] Open
Abstract
BACKGROUND Carbon ion beams are well accepted as densely ionizing radiation with a high linear energy transfer (LET). However, the current clinical practice does not fully exploit the highest possible dose-averaged LET (LETd) and, consequently, the biological potential in the target. This aspect becomes worse in larger tumors for which inferior clinical outcomes and corresponding lower LETd was reported. PURPOSE The vicinity to critical organs in general and the inferior overall survival reported for larger sacral chordomas treated with carbon ion radiotherapy (CIRT), makes the treatment of such tumors challenging. In this work it was aimed to increase the LETd in large volume tumors while maintaining the relative biological effectiveness (RBE)-weighted dose, utilizing the LETd optimization functions of a commercial treatment planning system (TPS). METHODS Ten reference sequential boost carbon ion treatment plans, designed to mimic clinical plans for large sacral chordoma tumors, were generated. High dose clinical target volumes (CTV-HD) larger than250 cm 3 $250 \,{\rm cm}^{3}$ were considered as large targets. The total RBE-weighted median dose prescription with the local effect model (LEM) wasD RBE , 50 % = 73.6 Gy $\textrm {D}_{\rm RBE, 50\%}=73.6 \,{\rm Gy}$ in 16 fractions (nine to low dose and seven to high dose planning target volume). No LETd optimization was performed in the reference plans, while LETd optimized plans used the minimum LETd (Lmin) optimization function in RayStation 2023B. Three different Lmin values were investigated and specified for the seven boost fractions:L min = 60 keV / μ m $\textrm {L}_{\rm min}=60 \,{\rm keV}/{\umu }{\rm m}$ ,L min = 80 keV / μ m $\textrm {L}_{\rm min}=80 \,{\rm keV}/{\umu }{\rm m}$ andL min = 100 keV / μ m $\textrm {L}_{\rm min}=100 \,{\rm keV}/{\umu }{\rm m}$ . To compare the LETd optimized against reference plans, LETd and RBE-weighted dose based goals similar to and less strict than clinical ones were specified for the target. The goals for the organs at risk (OAR) remained unchanged. Robustness evaluation was studied for eight scenarios (± 3.5 % $\pm 3.5\%$ range uncertainty and± 3 mm $\pm 3 \,{\rm mm}$ setup uncertainty along the main three axes). RESULTS The optimization method withL min = 60 keV / μ m $\textrm {L}_{\rm min}=60 \,{\rm keV}/{\umu }{\rm m}$ resulted in an optimal LETd distribution with an average increase ofLET d , 98 % ${\rm {LET}}_{{\rm {d,}}98\%}$ (andLET d , 50 % ${\rm {LET}}_{{\rm {d,}}50\%}$ ) in the CTV-HD by8.9 ± 1.5 keV / μ m $8.9\pm 1.5 \,{\rm keV}/{\umu }{\rm m}$ (27 % $27\%$ ) (and6.9 ± 1.3 keV / μ m $6.9\pm 1.3 \,{\rm keV}/{\umu }{\rm m}$ (17 % $17\%$ )), without significant difference in the RBE-weighted dose. By allowing± 5 % $\pm 5\%$ over- and under-dosage in the target, theLET d , 98 % ${\rm {LET}}_{{\rm {d,}}98\%}$ (andLET d , 50 % ${\rm {LET}}_{{\rm {d,}}50\%}$ ) can be increased by11.3 ± 1.2 keV / μ m $11.3\pm 1.2 \,{\rm keV}/{\umu }{\rm m}$ (34 % $34\%$ ) (and11.7 ± 3.4 keV / μ m $11.7\pm 3.4 \,{\rm keV}/{\umu }{\rm m}$ (29 % $29\%$ )), using the optimization parametersL min = 80 keV / μ m $\textrm {L}_{\rm min}=80 \,{\rm keV}/{\umu }{\rm m}$ . The pass rate for the OAR goals in the LETd optimized plans was in the same level as the reference plans. LETd optimization lead to less robust plans compared to reference plans. CONCLUSIONS Compared to conventionally optimized treatment plans, the LETd in the target was increased while maintaining the RBE-weighted dose using TPS LETd optimization functionalities. Regularly assessing RBE-weighted dose robustness and acquiring more in-room images remain crucial and inevitable aspects during treatment.
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Affiliation(s)
- Mansure Schafasand
- Department of General and Translational Oncology and Hematology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | | | - Ankita Nachankar
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- ACMIT Gmbh, Wiener Neustadt, Austria
| | - Joanna Góra
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | | | | | | | - Dietmar Georg
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Piero Fossati
- Department of General and Translational Oncology and Hematology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | | | - Markus Stock
- Department of General and Translational Oncology and Hematology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
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Thwaites DI, Prokopovich DA, Garrett RF, Haworth A, Rosenfeld A, Ahern V. The rationale for a carbon ion radiation therapy facility in Australia. J Med Radiat Sci 2024; 71 Suppl 2:59-76. [PMID: 38061984 PMCID: PMC11011608 DOI: 10.1002/jmrs.744] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 11/17/2023] [Indexed: 04/13/2024] Open
Abstract
Australia has taken a collaborative nationally networked approach to achieve particle therapy capability. This supports the under-construction proton therapy facility in Adelaide, other potential proton centres and an under-evaluation proposal for a hybrid carbon ion and proton centre in western Sydney. A wide-ranging overview is presented of the rationale for carbon ion radiation therapy, applying observations to the case for an Australian facility and to the clinical and research potential from such a national centre.
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Affiliation(s)
- David I. Thwaites
- Institute of Medical Physics, School of PhysicsUniversity of SydneySydneyNew South WalesAustralia
- Department of Radiation OncologySydney West Radiation Oncology NetworkWestmeadNew South WalesAustralia
- Radiotherapy Research Group, Institute of Medical ResearchSt James's Hospital and University of LeedsLeedsUK
| | | | - Richard F. Garrett
- Australian Nuclear Science and Technology OrganisationLucas HeightsNew South WalesAustralia
| | - Annette Haworth
- Institute of Medical Physics, School of PhysicsUniversity of SydneySydneyNew South WalesAustralia
- Department of Radiation OncologySydney West Radiation Oncology NetworkWestmeadNew South WalesAustralia
| | - Anatoly Rosenfeld
- Centre for Medical Radiation Physics, School of PhysicsUniversity of WollongongSydneyNew South WalesAustralia
| | - Verity Ahern
- Department of Radiation OncologySydney West Radiation Oncology NetworkWestmeadNew South WalesAustralia
- Westmead Clinical School, Faculty of Medicine and HealthUniversity of SydneySydneyNew South WalesAustralia
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Nachankar A, Schafasand M, Hug E, Martino G, Góra J, Carlino A, Stock M, Fossati P. Sacral-Nerve-Sparing Planning Strategy in Pelvic Sarcomas/Chordomas Treated with Carbon-Ion Radiotherapy. Cancers (Basel) 2024; 16:1284. [PMID: 38610962 PMCID: PMC11010899 DOI: 10.3390/cancers16071284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/20/2024] [Accepted: 03/23/2024] [Indexed: 04/14/2024] Open
Abstract
To minimize radiation-induced lumbosacral neuropathy (RILSN), we employed sacral-nerve-sparing optimized carbon-ion therapy strategy (SNSo-CIRT) in treating 35 patients with pelvic sarcomas/chordomas. Plans were optimized using Local Effect Model-I (LEM-I), prescribed DRBE|LEM-I|D50% (median dose to HD-PTV) = 73.6 (70.4-76.8) Gy (RBE)/16 fractions. Sacral nerves were contoured between L5-S3 levels. DRBE|LEM-I to 5% of sacral nerves-to-spare (outside HD-CTV) (DRBE|LEM-I|D5%) were restricted to <69 Gy (RBE). The median follow-up was 25 months (range of 2-53). Three patients (9%) developed late RILSN (≥G3) after an average period of 8 months post-CIRT. The RILSN-free survival at 2 years was 91% (CI, 81-100). With SNSo-CIRT, DRBE|LEM-I|D5% for sacral nerves-to-spare = 66.9 ± 1.9 Gy (RBE), maintaining DRBE|LEM-I to 98% of HD-CTV (DRBE|LEM-I|D98%) = 70 ± 3.6 Gy (RBE). Two-year OS and LC were 100% and 93% (CI, 84-100), respectively. LETd and DRBE with modified-microdosimetric kinetic model (mMKM) were recomputed retrospectively. DRBE|LEM-I and DRBE|mMKM were similar, but DRBE-filtered-LETd was higher in sacral nerves-to-spare in patients with RILSN than those without. At DRBE|LEM-I cutoff = 64 Gy (RBE), 2-year RILSN-free survival was 100% in patients with <12% of sacral nerves-to-spare voxels receiving LETd > 55 keV/µm than 75% (CI, 54-100) in those with ≥12% of voxels (p < 0.05). DRBE-filtered-LETd holds promise for the SNSo-CIRT strategy but requires longer follow-up for validation.
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Affiliation(s)
- Ankita Nachankar
- ACMIT Gmbh, 2700 Wiener Neustadt, Austria
- Department of Radiation Oncology, MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria; (E.H.); (P.F.)
| | - Mansure Schafasand
- Department of Medical Physics, MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria; (M.S.); (G.M.); (J.G.); (A.C.); (M.S.)
- Department of Radiation Oncology, Medical University of Vienna, 1090 Wien, Austria
- Division Medical Physics, Karl Landsteiner University of Health Sciences, 3500 Krems an der Donau, Austria
| | - Eugen Hug
- Department of Radiation Oncology, MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria; (E.H.); (P.F.)
| | - Giovanna Martino
- Department of Medical Physics, MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria; (M.S.); (G.M.); (J.G.); (A.C.); (M.S.)
| | - Joanna Góra
- Department of Medical Physics, MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria; (M.S.); (G.M.); (J.G.); (A.C.); (M.S.)
| | - Antonio Carlino
- Department of Medical Physics, MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria; (M.S.); (G.M.); (J.G.); (A.C.); (M.S.)
| | - Markus Stock
- Department of Medical Physics, MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria; (M.S.); (G.M.); (J.G.); (A.C.); (M.S.)
- Division Medical Physics, Karl Landsteiner University of Health Sciences, 3500 Krems an der Donau, Austria
| | - Piero Fossati
- Department of Radiation Oncology, MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria; (E.H.); (P.F.)
- Division Radiation Oncology, Karl Landsteiner University of Health Sciences, 3500 Krems an der Donau, Austria
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Cartechini G, Missiaggia M, Scifoni E, La Tessa C, Cordoni FG. Integrating microdosimetric in vitroRBE models for particle therapy into TOPAS MC using the MicrOdosimetry-based modeliNg for RBE ASsessment (MONAS) tool. Phys Med Biol 2024; 69:045005. [PMID: 38211313 DOI: 10.1088/1361-6560/ad1d66] [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: 07/17/2023] [Accepted: 01/11/2024] [Indexed: 01/13/2024]
Abstract
Objective.In this paper, we present MONAS (MicrOdosimetry-based modelliNg for relative biological effectiveness (RBE) ASsessment) toolkit. MONAS is a TOPAS Monte Carlo extension, that combines simulations of microdosimetric distributions with radiobiological microdosimetry-based models for predicting cell survival curves and dose-dependent RBE.Approach.MONAS expands TOPAS microdosimetric extension, by including novel specific energy scorers to calculate the single- and multi-event specific energy microdosimetric distributions at different micrometer scales. These spectra are used as physical input to three different formulations of themicrodosimetric kinetic model, and to thegeneralized stochastic microdosimetric model(GSM2), to predict dose-dependent cell survival fraction and RBE. MONAS predictions are then validated against experimental microdosimetric spectra andin vitrosurvival fraction data. To show the MONAS features, we present two different applications of the code: (i) the depth-RBE curve calculation from a passively scattered proton SOBP and monoenergetic12C-ion beam by using experimentally validated spectra as physical input, and (ii) the calculation of the 3D RBE distribution on a real head and neck patient geometry treated with protons.Main results.MONAS can estimate dose-dependent RBE and cell survival curves from experimentally validated microdosimetric spectra with four clinically relevant radiobiological models. From the radiobiological characterization of a proton SOBP and12C fields, we observe the well-known trend of increasing RBE values at the distal edge of the radiation field. The 3D RBE map calculated confirmed the trend observed in the analysis of the SOBP, with the highest RBE values found in the distal edge of the target.Significance.MONAS extension offers a comprehensive microdosimetry-based framework for assessing the biological effects of particle radiation in both research and clinical environments, pushing closer the experimental physics-based description to the biological damage assessment, contributing to bridging the gap between a microdosimetric description of the radiation field and its application in proton therapy treatment with variable RBE.
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Affiliation(s)
- Giorgio Cartechini
- Department of Radiation Oncology, University of Miami Miller School of Medicine, 1550 NW 10th Avenue, 33126, Miami (FL), United States of America
- Trento Institute for Fundamental Physics and Application (TIFPA), via Sommarive 15, I-38123, Trento, Italy
| | - Marta Missiaggia
- Department of Radiation Oncology, University of Miami Miller School of Medicine, 1550 NW 10th Avenue, 33126, Miami (FL), United States of America
- Trento Institute for Fundamental Physics and Application (TIFPA), via Sommarive 15, I-38123, Trento, Italy
| | - Emanuele Scifoni
- Trento Institute for Fundamental Physics and Application (TIFPA), via Sommarive 15, I-38123, Trento, Italy
| | - Chiara La Tessa
- Department of Radiation Oncology, University of Miami Miller School of Medicine, 1550 NW 10th Avenue, 33126, Miami (FL), United States of America
- Trento Institute for Fundamental Physics and Application (TIFPA), via Sommarive 15, I-38123, Trento, Italy
- Department of Physics, University of Trento, via Sommarive 14, I-38123, Trento, Italy
| | - Francesco G Cordoni
- Trento Institute for Fundamental Physics and Application (TIFPA), via Sommarive 15, I-38123, Trento, Italy
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, I-38123, Trento, Italy
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Verona C, Barna S, Georg D, Hamad Y, Magrin G, Marinelli M, Meouchi C, Verona Rinati G. Diamond based integrated detection system for dosimetric and microdosimetric characterization of radiotherapy ion beams. Med Phys 2024; 51:533-544. [PMID: 37656015 DOI: 10.1002/mp.16698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 08/02/2023] [Accepted: 08/04/2023] [Indexed: 09/02/2023] Open
Abstract
BACKGROUND Ion beam therapy allows for a substantial sparing of normal tissues and higher biological efficacy. Synthetic single crystal diamond is a very good material to produce high-spatial-resolution and highly radiation hard detectors for both dosimetry and microdosimetry in ion beam therapy. PURPOSE The aim of this work is the design, fabrication and test of an integrated waterproof detector based on synthetic single crystal diamond able to simultaneously perform dosimetric and microdosimetric characterization of clinical ion beams. METHODS The active elements of the integrated diamond device, that is, dosimeter and microdosimeter, were both realized in a Schottky diode configuration featured by different area, thickness, and shape by means of photolithography technologies for the selective growth of intrinsic and boron-doped CVD diamond. The cross-section of the sensitive volume of the dosimetric element is 4 mm2 and 1 μm-thick, while the microdosimetric one has an active cross-sectional area of 100 × 100 μm2 and a thickness of about 6.2 μm. The dosimetric and microdosimetric performance of the developed device was assessed at different depths in a water phantom at the MedAustron ion beam therapy facility using a monoenergetic uniformly scanned carbon ion beam of 284.7 MeV/u and proton beam of 148.7 MeV. The particle flux in the region of the microdosimeter was 6·107 cm2 /s for both irradiation fields. At each depth, dose and dose distributions in lineal energy were measured simultaneously and the dose mean lineal energy values were then calculated. Monte Carlo simulations were also carried out by using the GATE-Geant4 code to evaluate the relative dose, dose averaged linear energy transfer (LETd ), and microdosimetric spectra at various depths in water for the radiation fields used, by considering the contribution from the secondary particles generated in the ion interaction processes as well. RESULTS Dosimetric and microdosimetric quantities were measured by the developed prototype with relatively low noise (∼2 keV/μm). A good agreement between the measured and simulated dose profiles was found, with discrepancies in the peak to plateau ratio of about 3% and 4% for proton and carbon ion beams respectively, showing a negligible LET dependence of the dosimetric element of the device. The microdosimetric spectra were validated with Monte Carlo simulations and a good agreement between the spectra shapes and positions was found. Dose mean lineal energy values were found to be in close agreement with those reported in the literature for clinical ion beams, showing a sharp increase along the Bragg curve, being also consistent with the calculated LETd for all depths within the experimental error of 10%. CONCLUSIONS The experimental indicate that the proposed device can allow enhanced dosimetry in particle therapy centers, where the absorbed dose measurement is implemented by the microdosimetric characterization of the radiation field, thus providing complementary results. In addition, the proposed device allows for the reduction of the experimental uncertainties associated with detector positioning and could facilitate the partial overcoming of some drawbacks related to the low sensitivity of diamond microdosimeters to low LET radiation.
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Affiliation(s)
- Claudio Verona
- Dipartimento di Ingegneria Industriale, Università di Roma "Tor Vergata", Sez. INFN-Roma2, Roma, Italia, Italy
| | - Sandra Barna
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Yasmin Hamad
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Giulio Magrin
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Marco Marinelli
- Dipartimento di Ingegneria Industriale, Università di Roma "Tor Vergata", Sez. INFN-Roma2, Roma, Italia, Italy
| | - Cynthia Meouchi
- Institute of Atomic and Subatomic Physics, Vienna University of Technology, Vienna, Austria
| | - Gianluca Verona Rinati
- Dipartimento di Ingegneria Industriale, Università di Roma "Tor Vergata", Sez. INFN-Roma2, Roma, Italia, Italy
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Heuchel L, Hahn C, Ödén J, Traneus E, Wulff J, Timmermann B, Bäumer C, Lühr A. The dirty and clean dose concept: Towards creating proton therapy treatment plans with a photon-like dose response. Med Phys 2024; 51:622-636. [PMID: 37877574 DOI: 10.1002/mp.16809] [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: 07/03/2023] [Revised: 10/11/2023] [Accepted: 10/11/2023] [Indexed: 10/26/2023] Open
Abstract
BACKGROUND Applying tolerance doses for organs at risk (OAR) from photon therapy introduces uncertainties in proton therapy when assuming a constant relative biological effectiveness (RBE) of 1.1. PURPOSE This work introduces the novel dirty and clean dose concept, which allows for creating treatment plans with a more photon-like dose response for OAR and, thus, less uncertainties when applying photon-based tolerance doses. METHODS The concept divides the 1.1-weighted dose distribution into two parts: the clean and the dirty dose. The clean and dirty dose are deposited by protons with a linear energy transfer (LET) below and above a set LET threshold, respectively. For the former, a photon-like dose response is assumed, while for the latter, the RBE might exceed 1.1. To reduce the dirty dose in OAR, a MaxDirtyDose objective was added in treatment plan optimization. It requires setting two parameters: LET threshold and max dirty dose level. A simple geometry consisting of one target volume and one OAR in water was used to study the reduction in dirty dose in the OAR depending on the choice of the two MaxDirtyDose objective parameters during plan optimization. The best performing parameter combinations were used to create multiple dirty dose optimized (DDopt) treatment plans for two cranial patient cases. For each DDopt plan, 1.1-weighted dose, variable RBE-weighted dose using the Wedenberg RBE model and dose-average LETd distributions as well as resulting normal tissue complication probability (NTCP) values were calculated and compared to the reference plan (RefPlan) without MaxDirtyDose objectives. RESULTS In the water phantom studies, LET thresholds between 1.5 and 2.5 keV/µm yielded the best plans and were subsequently used. For the patient cases, nearly all DDopt plans led to a reduced Wedenberg dose in critical OAR. This reduction resulted from an LET reduction and translated into an NTCP reduction of up to 19 percentage points compared to the RefPlan. The 1.1-weighted dose in the OARs was slightly increased (patient 1: 0.45 Gy(RBE), patient 2: 0.08 Gy(RBE)), but never exceeded clinical tolerance doses. Additionally, slightly increased 1.1-weighted dose in healthy brain tissue was observed (patient 1: 0.81 Gy(RBE), patient 2: 0.53 Gy(RBE)). The variation of NTCP values due to variation of α/β from 2 to 3 Gy was much smaller for DDopt (2 percentage points (pp)) than for RefPlans (5 pp). CONCLUSIONS The novel dirty and clean dose concept allows for creating biologically more robust proton treatment plans with a more photon-like dose response. The reduced uncertainties in RBE can, therefore, mitigate uncertainties introduced by using photon-based tolerance doses for OAR.
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Affiliation(s)
- Lena Heuchel
- Department of Physics, TU Dortmund University, Dortmund, Germany
| | - Christian Hahn
- Department of Physics, TU Dortmund University, Dortmund, Germany
- OncoRay-National Center of Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
- Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Jakob Ödén
- RaySearch Laboratories AB, Stockholm, Sweden
| | | | - Jörg Wulff
- West German Proton Therapy Center Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
| | - Beate Timmermann
- West German Proton Therapy Center Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
- Department of Particle Therapy, University Hospital Essen, Essen, Germany
- German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Essen, Germany
| | - Christian Bäumer
- Department of Physics, TU Dortmund University, Dortmund, Germany
- West German Proton Therapy Center Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
- German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Essen, Germany
| | - Armin Lühr
- Department of Physics, TU Dortmund University, Dortmund, Germany
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Schafasand M, Resch AF, Nachankar A, Gora J, Traneus E, Glimelius L, Georg D, Stock M, Carlino A, Fossati P. Investigation on the physical dose filtered by linear energy transfer for treatment plan evaluation in carbon ion therapy. Med Phys 2024; 51:556-565. [PMID: 37727137 DOI: 10.1002/mp.16751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 08/22/2023] [Accepted: 09/01/2023] [Indexed: 09/21/2023] Open
Abstract
BACKGROUND Large tumor size has been reported as a predicting factor for inferior clinical outcome in carbon ion radiotherapy (CIRT). Besides the clinical factors accompanied with such tumors, larger tumors receive typically more low linear energy transfer (LET) contributions than small ones which may be the underlying physical cause. Although dose averaged LET is often used as a single parameter descriptor to quantify the beam quality, there is no evidence that this parameter is the optimal clinical predictor for the complex mixed radiation fields in CIRT. PURPOSE Purpose of this study was to investigate on a novel dosimetric quantity, namely high-LET-dose (D > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ , the physical dose filtered based on an LET threshold) as a single parameter estimator to differentiate between carbon ion treatment plans (cTP) with a small and large tumor volume. METHODS Ten cTPs with a planning target volume,PTV ≥ 500 cm 3 $\mathrm{PTV}\ge {500}\,{{\rm cm}^{3}}$ (large) and nine with aPTV < 500 cm 3 $\mathrm{PTV}<{500}\,{{\rm cm}^{3}}$ (small) were selected for this study. To find a reasonable LET threshold (L thr $\textrm {L}_{\textrm {thr}}$ ) that results in a significant difference in terms ofD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ , the voxel based normalized high-LET-dose (D ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ ) distribution in the clinical target volume (CTV) was studied on a subset (12 out of 19 cTPs) for 18 LET thresholds, using standard distribution descriptors (mean, variance and skewness). The classical dose volume histogram concept was used to evaluate theD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ andD ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ distributions within the target of all 19 cTPs at the before determinedL thr $\textrm {L}_{\textrm {thr}}$ . Statistical significance of the difference between the two groups in terms of meanD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ andD ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ volume histogram parameters was evaluated by means of (two-sided) t-test or Mann-Whitney-U-test. In addition, the minimum target coverage at the above determinedL thr $\textrm {L}_{\textrm {thr}}$ was compared and validated against three other thresholds to verify its potential in differentiation between small and large volume tumors. RESULTS AnL thr $\textrm {L}_{\textrm {thr}}$ of approximately30 keV / μ m ${30}\,{\rm keV/}\umu {\rm m}$ was found to be a reasonable threshold to classify the two groups. At this threshold, theD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ andD ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ were significantly larger (p < 0.05 $p<0.05$ ) in small CTVs. For the small tumor group, the near-minimum and medianD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ (andD ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ ) in the CTV were in average9.3 ± 1.5 Gy $9.3\pm {1.5}\,{\rm Gy}$ (0.31 ± 0.08) and13.6 ± 1.6 Gy $13.6\pm {1.6}\,{\rm Gy}$ (0.46 ± 0.06), respectively. For the large tumors, these parameters were6.6 ± 0.2 Gy $6.6\pm {0.2}\,{\rm Gy}$ (0.20 ± 0.01) and8.6 ± 0.4 Gy $8.6\pm {0.4}\,{\rm Gy}$ (0.28 ± 0.02). The difference between the two groups in terms of mean near-minimum and medianD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ (D ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ ) was 2.7 Gy (11%) and 5.0 Gy (18%), respectively. CONCLUSIONS The feasibility of high-LET-dose based evaluation was shown in this study where a lowerD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ was found in cTPs with a large tumor size. Further investigation is needed to draw clinical conclusions. The proposed methodology in this work can be utilized for future high-LET-dose based studies.
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Affiliation(s)
- Mansure Schafasand
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | | | - Ankita Nachankar
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- ACMIT Gmbh, Wiener Neustadt, Austria
| | - Joanna Gora
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | | | | | - Dietmar Georg
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Markus Stock
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Oncology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
| | | | - Piero Fossati
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Oncology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
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