Raster-scanning Helium Ion Beam Therapy: Development and Validation of a Novel Treatment Planning System for Biophysical Modeling and Optimization PDF Download

Author: Andrea Mairani
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Since 2009, over 5000 patients have been treated with proton (1H) and carbon (12C) ion beams at the Heidelberg Ion Therapy Center (HIT). By 2020, HIT will begin the first clinical raster-scanning particle therapy program using helium (4He) ions, which exhibit favorable biophysical properties intermediate of clinically used light and heavy ions. Today, a commercial treatment planning system (TPS) for 4He ions does not exist. This calls for an extensive development, testing and verification of a TPS for 4He ions, exploring both physical and biological dose models.This year, a GPU-based dose computation code for particle therapy (FRoG) was developed at HIT. Due to its parallelized computation scheme, sophisticated beam model and outstanding performance in conditions with anatomical complexity, FRoG performs forward dose calculations within minutes (in contrast to full simulation with hour-long runtimes) in excellent agreement with the clinical gold standard Monte Carlo simulations and measurements. Recent efforts focus on dose optimization (both physical and biological) for raster-scanning 4He ions beam therapy. A fully functional TPS within the FRoG framework will be devised and clinically integrated for 4He ion beams.Furthermore, biological phenomena of 4He ion beams remains poorly explored since the shutdown of clinical trials at the Lawrence Berkely National Laboratory in the early 1990u2019s. Potential biophysical and mechanistic approaches to modeling the relative biological effectives (RBE) in the clinic are under investigation in preparations for the first in-man treatment with raster-scanning 4He ion beams.

Author: Stewart Mein
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Radiotherapy with protons and heavier ions landmarks a novel era in the field of highprecision cancer therapy. To identify patients most benefiting from this technologically demanding therapy, fast assessment of comparative treatment plans utilizing different ion species is urgently needed. Moreover, to overcome uncertainties of actual in-vivo physical dose distribution and biological effects elicited by different radiation qualities, development of a reliable high-throughput algorithm is required. To this end, we engineered a unique graphics processing unit (GPU) based software architecture allowing rapid and robust dose calculation. Fast dose Recalculation on GPU (FRoG) currently operates with four particle beams, i.e., raster-scanning proton, helium, carbon and oxygen ions. Designed to perform fast and accurate calculations for both physical and biophysical quantities, FRoG operates an advanced analytical pencil beam algorithm using parallelized procedures on a GPU. Clinicians and medical physicists can assess both dose and dose-averaged linear energy transfer (LET) distributions for proton therapy (and in turn effective dose by applying variable RBE schemes) to further scrutinize plans for acceptance or potential re-planning purposes within minutes. In addition, various biological model predictions are readily accessible for heavy ion therapy, such as the local effect model (LEM) and microdosimetric kinetic model (MKM). FRoG has been extensively benchmarked against gold standard Monte Carlo simulations and experimental data. Evaluating against commercial treatment planning systems demonstrates the strength of FRoG in better predicting dose distributions in complex clinical settings. In preparation for the upcoming translation of novel ions, case-/disease-specific ion-beam selection and advanced multi-particle treatment modalities at the Heidelberg Ion-beam Therapy Center (HIT), we quantified the accuracy limits in particle therapy treatment planning under complex heterogeneous conditions for the four ions (p, 4He, 12C, 16O) for various dose engines, both analytical algorithms and Monte Carlo code. Devised in-house, FRoG landmarks the first GPU-based treatment planning system (non commercial) for raster-scanning 4He ion beams, with an official treatment program set for early 2020. Since its inception, FRoG has been installed and is currently in operation clinically at four centers across Europe: HIT (Heidelberg, Germany), CNAO (Pavia, Italy) , Aarhus (Denmark) and the Normandy Proton Therapy Center (Caen, France). Here, the development and validation of FRoG as well as clinical investigations and advanced topics in particle therapy dose calculation are covered. The thesis is presented in cumulative format and comprises four peer reviewed publications.

Author: Stewart Mein
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Benedikt Kopp
Publisher:
ISBN:
Category :
Languages : en
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The Heidelberg Ion-Beam Therapy Center (HIT) uses the Raster Scan technique for proton and carbon ions. The treatment planning system (TPS) RayStation, Raysearch Laboratories, will be integrated into the application system IONTRIS, Siemens Healthineers.As TPS commissioning for proton and carbon ions various cases of target volumes were optimized with the clinical TPS Syngo RT Planning, Siemens Healthineers, using a Pencil Beam (PB) algorithm. Dose distributions rising from simple geometries like cubic volumes in water to complex cases like anthropomorphic Rando Alderson head phantom and double-wedge phantom were recalculated in RayStation using a PB algorithm for Carbons and Monte Carlo (MC) for Protons. RayStation dose distributions were compared with syngo TPS calculations and to measurements with a 24 Pin-Point chamber array in a water phantom and for complex geometries with the 2D array Octavius1000SRS, both PTW.For Protons both TPS were comparable for simple geometries. The RayStation MC algorithm better describes the lateral spread of the proton beam passing a range modulator and an air gap of 20 cm. For complex geometries, including cases with lateral inhomogeneities or oblique entrance, the RayStation MC shows better agreement with the measurements. The carbon PB calculation is on the same level of precision as the Syngo TPS for all geometries.Still based on preliminary basis data, the RayStation dose calculation yields excellent results. We are looking forward to integrating RayStation into clinical routine and making use of its powerful tools.

Author: Michael Farley Moyers
Publisher:
ISBN: 9781930524552
Category : Science
Languages : en
Pages : 580

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This book is indexed and includes a DVD with color images and tables. The number of light ion beam (including proton beam) treatment programs is rapidly increasing worldwide; however, there are currently no practical guides to support the acceptance testing, commissioning, planning, and continuing quality assurance of these programs. This book is aimed at those individuals who participate in the delivery and planning aspects of light ion beam treatments. Typically these individuals are medical physicists with responsibilities for calibration and verification of beam delivery, quality assurance, and computerized treatment planning; however other individuals may also find the book useful. This book provides practical recommendations and guides the reader through the steps of the treatment process, focusing on practical details.

Author: Mansure Schafasand
Publisher:
ISBN:
Category :
Languages : en
Pages : 123

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At MedAustron Ion Therapy Center (MA) patients are treated with protons (since 12/2016) and carbon ions (since 7/2019). In 2020, the medical commissioning of the Vertical Beam Line installed in Irradiation Room 2 (IR2VBL) with carbon ions started. This work reports the dosimetric commissioning of the Treatment Planning System (TPS) RayStation v8B (RS, RaySearch laboratories, Sweden) for the IR2VBL with carbon ions at MA. The validation was performed for isocentric and non-isocentric setups and the focus was on the carbon pencil beam dose calculation algorithm (v3.0) available in RS. The verified parameters for the 1D/2D validation were the integrated radial profiles as function of depth, the spot profiles and the beam model calibration. For the 3D validation several test cases with different complexity were used. The relative dose deviation between the TPS and the measured dose (at 75% of Range_80) was within ±0.1% for all energies. Part of the commissioning is to translate the commissioning findings to Patient Specific Quality Assurance (PSQA). Hence, the second part of the thesis focused on the analysis of PSQA trend lines for all patients treated at MA during the first three years of clinical operation. Those measurements are performed for each patient before treatment. A comparison between the planned and measured dose is presented in the current work for different selection criteria like dose calculation algorithm, anatomical site, etc. The overestimation of the pencil beam algorithm for both particle types, when a range shifter is inserted, was observed in the results of both parts.*****At MedAustron Ion Therapy Center (MA) patients are treated with protons (since 12/2016) and carbon ions (since 7/2019). In 2020, the medical commissioning of the Vertical Beam Line installed in Irradiation Room 2 (IR2VBL) with carbon ions started. This work reports the dosimetric commissioning of the Treatment Planning System (TPS) RayStation v8B (RS, RaySearch laboratories, Sw

Author: Halil Ozan Gozbasi
Publisher:
ISBN:
Category : Cancer
Languages : en
Pages :

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External beam radiotherapy is delivered from outside the body aimed at cancer cells to damage their DNA making them unable to divide and reproduce. The beams travel through the body and may damage nearby healthy tissues unless carefullyplanned. Therefore, the goal of treatment plan optimization is to find the best system configuration to deliver sufficient dose to target structures while avoiding damage to healthy tissues. This thesis investigates optimization approaches for two external beam radiation therapy techniques: Intensity-Modulated Radiation Therapy (IMRT) and Volumetric-Modulated Arc Therapy (VMAT). We develop an automated treatment planning technology for IMRT which generates several high-quality treatment plans satisfying the provided requirements in a single invocation and without human guidance. Our approach is based on an existing linear programming-based fluence map optimization model that approximates dose-volume requirements using conditional value-at-risk (C-VaR) constraints. We show how the parameters of the C-VaR constraints can be used to control various metrics of treatment plan quality. A novel bi-criteria scoring based beam selection algorithm is developed which finds the best beam configuration at least ten times faster for real-life brain, prostate, and head and neck cases as compared to an exact mixed integer programming model. Patient anatomy changes due to breathing during the treatment of lung cancer need to be considered in treatment planning. To date, a single phase of the breathing cycle is typically selected for treatment and radiation is shut-off in other phases. We investigate optimization technology that finds optimal fluence maps for each phase of the breathing cycle by considering the overall dose delivered to a patient using image registration algorithms to track target structures and organs at risk. Because the optimization exploits the opportunities provided in each phase, better treatment plans are obtained. The improvements are shown on a real-life lung case. VMAT is a recent radiation treatment technology which has the potential to provide treatments in less time compared to other delivery techniques. This enhances patient comfort and allows for the treatment of more patients. We build a large-scale mixed-integer programming model for VMAT treatment plan optimization. The solution of this model is computationally prohibitive. Therefore, we develop an iterative MIP-based heuristic algorithm which solves the model multiple times on a reduced set of decision variables. We introduce valid inequalities that decrease solution times, and, more importantly, that identify higher quality integer solutions within specified time limits. Computational studies on a spinal tumor and a prostate tumor case produce clinically acceptable results.

Author: Andrea Mairani
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Radiotherapy with protons and heavier ions landmarks a novel era in the field of high-precision cancer therapy. To identify patients most benefiting from this technologically demanding therapy, fast assessment of comparative treatment plans utilizing different ion species is urgently needed. Moreover, to overcome uncertainties of actual in-vivo physical dose distribution and biological effects elicited by different radiation qualities, development of a reliable high-throughput algorithm is required. To this end, we engineered a unique graphics processing unit (GPU) based software architecture allowing rapid and robust dose calculation. Fast dose Recalculation on GPU, FRoG, currently operates with four particle beams, i.e., raster-scanning proton, helium, carbon and oxygen ions. Designed to perform fast and accurate calculations for both physical and biophysical quantities, FRoG operates an advanced analytical pencil beam algorithm using parallelized procedures on a GPU. Clinicians and medical physicists can assess both dose and dose-averaged LET distributions for proton therapy (and eventually DRBE by applying variable RBE schemes) to further scrutinize plans for acceptance or potential re-planning purposes within minutes. In addition, various biological model predictions are readily accessible for heavy ion therapy, such as LEM and MKM. FRoG has been extensively benchmarked against gold standard Monte Carlo simulations and experimental data. Evaluating against commercial treatment planning systems demonstrates the strength of FRoG in better predicting dose distributions in complex clinical settings. A summary of the recent clinical investigations with FRoG will be presented.

Author: Nicholas Pierre Nelson
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Dynamically collimated proton therapy (DC-PT) is a derived form of pencil beam scanning proton therapy (PBS-PT) and is gaining interest in the field of radiation therapy. In pencil beam scanning, near-monoenergetic beamlets of protons are magnetically swept across target volumes in successive energy layers at depths dictated by the Bragg peak depth. The achievable dosimetric benefits associated with PBS are largely dependent on pencil beam width, which can be reduced through collimation. Therefore, a Dynamic Collimation System (DCS) was proposed by Hyer et al. in 2014 to enable energy layer-specific collimation in PBS-PT, or DC-PT. This work focuses on the development and validation of the dosimetric benefits proposed by the DCS through Monte Carlo methods and experimental techniques using the clinical prototype of the DCS equipped to the PBS-PT system located at the Miami Cancer Institute (MCI). First, a Monte Carlo beam model was developed using uncollimated beam measurements performed at MCI. This uncollimated beam model was then extended to include the beam-modifying components of the DCS and subsequently validated against measurements of DCS-collimated beamlets. Additionally, the model of DCS' accessory range shifter, which is required to treat at depths below 4 cm in water, was validated in terms of water equivalent thickness and spot size broadening. Novel beam and DCS modeling techniques that were necessitated by the focused design of the DCS trimmers were developed to achieve excellent agreement with experimental data. Collimated beamlet measurements consisting of integral depth dose curves and two-dimensional profiles were used to verify the increase in entrance dose and sharpened penumbra caused by collimation, respectively. Following the development of the Monte Carlo model, simple and complex treatment plans were developed to characterize the dosimetric benefits of the DCS and mechanically integrate the DCS with the PBS beamline at MCI. The treatment plans consisted of cubic target geometries that were treated with multiple energy layers, where reductions in penumbra were parametrized as a function of treatment depth, lateral field size, and trimmer-to-surface distance. Through this, it was found that the achievable penumbra with the DCS was independent of the lateral field size, and for non-range shifted plans, the trimmer-to-surface distance. For range shifted plans, increases in the trimmer-to-surface distance were found to directly reduce the achievable penumbra. Penumbra reductions of up to 64% were observed at a depth of 5 cm with the use of the DCS. The cubic plans allowed for an idealized geometry that was favorable to facilitate initial investigations into treatment plan creation and optimization. Additionally, the multi-energy cubic plans did not require integration between the DCS trimmers and beam scanning controller, which was not available at the time. Because of this, the trimmers and beam delivery were operated independently, and trimmers were moved in between energy layers. Optimized plan parameters were written to PBS layer definition files for delivery and measurements were performed using radiochromic film and an ionization chamber array to validate simulations. Treatment plans for clinically relevant target geometries were then developed following the successful characterization of the cubic plans. These plans significantly differed from the cubic plans in that they required the trimmers to move on a spot-by-spot basis, which is the expected clinical delivery scenario. To accomplish this, treatment planning methods that were used for the cubic plans were extended to support treatment planning for clinically relevant delivery patterns, where trimmer configurations were strategically selected to yield the most efficient and conformal treatments. Treatment plans were created for multiple target shapes placed at various depths that were treated with and without the range shifter. Normal tissue rinds, which are a region of expansion into the healthy tissue surrounding the target, were evaluated to gauge the effectiveness of collimation. Through this, dose reductions of up to 12% and 45% were observed within 10- and 30-mm normal tissue rinds. Subsequent measurements were then carried out for one of the target shapes at three depths. To accomplish delivery, the DCS trimmer control system was integrated with the beam scanning controller system to move the trimmers on a spot-by-spot basis. Measurements were then performed to provide insight into the accuracy of the fully integrated delivery and validity of the simulated normal tissue dose reductions. This work presents a significant advancement in the development of the DCS technology. Prior to this work, literature supporting the use of the DCS primarily consisted of computational treatment planning studies and experimental studies of single beamlet irradiations. These contributions were invaluable to the continued interest in the development of the DCS and ultimately led to the design and fabrication of a clinical DCS prototype with intentions for integration with a clinical delivery system. Therefore, this work builds upon the existing literature by providing the first experimental evidence that demonstrates the dosimetric benefits of the DCS for composite treatment fields. Additionally, the methods utilized in this work have been applied to other aspects of the DCS implementation, such as the development of dose calculation algorithms and the establishment of mechanical tolerances. In conclusion, the Dynamic Collimation System significantly improves the lateral dose conformity in PBS-PT. The utility of DC-PT delivered with the DCS has been thoroughly demonstrated through computational and experimental studies. Now fully integrated with a clinical delivery system, the DCS is quickly advancing toward clinical use. This dissertation has provided the first experimental data supporting the effectiveness of DC-PT with the DCS and other aspects of the DCS implementation that will contribute to safe and effective clinical use.

Author: Michael Goitein
Publisher: Springer Science & Business Media
ISBN: 0387726454
Category : Science
Languages : en
Pages : 333

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Book Description
The papers collected in this hugely useful volume cover the principle physical and biological aspects of radiation therapy and in addition, address practical clinical considerations in the planning and delivering of that therapy. The importance of the assessment of uncertainties is emphasized. Topics include an overview of the physics of the interactions of radiation with matter and the definition of the goals and the design of radiation therapy approaches.