Radiobiologically based optimization of external beam radiotherapy techniques using a small number of fields
Author: Svante Söderström
Publisher:
Published: 1995
Total Pages: 50
ISBN-13: 9789171533760
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Biologically Optimized Radiation Therapy
Author: Anders Brahme
Publisher: World Scientific Publishing Company
Published: 2014-03-21
Total Pages: 688
ISBN-13: 9814602507
DOWNLOAD EBOOKRadiation therapy has developed and advanced dramatically in the last few decades. However, very little has been published or done in the area of biologically optimized treatment planning. Development of Biologically Optimized Radiation Therapy aims to fill and close an important gap in the literature with a well-focused and in-depth content.The book covers the biological, physical and clinical background of advanced biologically based radiation therapy optimization with focus on modern radiation therapy modalities such as electron, photon and light ion therapy. Highly recommended for its strong interdisciplinary profile, the book contains a meritorious compilation of previously unpublished materials in many areas of modern science. Undergraduates, researchers and practitioners such as oncologists, medical physicists and radiation biologists alike should find the book immensely informative and comprehensively thorough.
Optimization of Field Matching in External Photon Beam Radiation Therapy
Author: Víctor Hernández Masgrau
Publisher:
Published: 2015
Total Pages: 54
ISBN-13:
DOWNLOAD EBOOKRadiation therapy is one of the main modalities used for treating cancer patients, together with surgery and chemotherapy. Radiotherapy treatments can be carried out with a great variety of devices, but most treatments are currently delivered with megavoltage x-ray beams produced by medical linear accelerators (linacs). Many treatments are carried out with adjacent radiation fields, which need to be matched. Field matching is a complex problem, which presents several geometrical and dosimetrical challenges. This thesis deals with different aspects related to field matching using medical linacs. The aim is to optimize the process in order to improve the accuracy of this technique in clinical practice. The results of the thesis are included in four publications. Two of them focus on the geometrical problem of field matching; the other two on the optimization in single-isocenter half-beam (SIHB) techniques. In the first group the geometrical problem of matching the adjacent fields is addressed. Fields with different isocenters can be matched by rotating the couch and the collimator and selecting the appropriate field sizes in such a way that their side planes are coincident. For the first time a general analytical solution to this problem, applicable to any field configuration, is presented. The solution provides all the parameters needed to achieve a geometrically exact match. Additionally, the general analytical solution permits to derive simplified expressions for particular treatment techniques. Another important advantage of the general solution is that it allows to draw practical conclusions regarding field matching in clinical practice. In the second group, issues regarding the SIHB technique are investigated. In this technique one of the asymmetric jaws is set to zero in such a way that half-fields with no divergence at the central axis are combined. First, the effect of the field setup on the dosimetry of abutted fields in SIHB techniques is analyzed. Results show that the field setup has an important influence on the dosimetry at the junction. Thus, having a uniform dose distribution for two fields at gantry 0° does not guarantee a uniform distribution for other field arrangements. In addition, junction doses are largely affected by the relative position of the radiation fields involved. Studies aiming to assess or to optimize the homogeneity of the dose distribution at the junction should, therefore, take this effect into account. Second, a new method to calibrate the zero jaw position is proposed that improves its accuracy. This is important because in the SIHB technique the zero position of the jaw is critical for the dose homogeneity at the junction. The presented method allows a more accurate and safer use of half-beam techniques.
Genetic and Evolutionary Computation — GECCO 2004
Author: Kalyanmoy Deb
Publisher: Springer
Published: 2004-06-01
Total Pages: 1490
ISBN-13: 3540248544
DOWNLOAD EBOOKThe two volume set LNCS 3102/3103 constitutes the refereed proceedings of the Genetic and Evolutionary Computation Conference, GECCO 2004, held in Seattle, WA, USA, in June 2004. The 230 revised full papers and 104 poster papers presented were carefully reviewed and selected from 460 submissions. The papers are organized in topical sections on artificial life, adaptive behavior, agents, and ant colony optimization; artificial immune systems, biological applications; coevolution; evolutionary robotics; evolution strategies and evolutionary programming; evolvable hardware; genetic algorithms; genetic programming; learning classifier systems; real world applications; and search-based software engineering.
Radiation Therapy Physics
Author: Alfred R. Smith
Publisher: Springer Science & Business Media
Published: 2013-11-11
Total Pages: 468
ISBN-13: 3662031078
DOWNLOAD EBOOKThe aim of this book is to provide a uniquely comprehensive source of information on the entire field of radiation therapy physics. The very significant advances in imaging, computational, and accelerator technologies receive full consideration, as do such topics as the dosimetry of radiolabeled antibodies and dose calculation models. The scope of the book and the expertise of the authors make it essential reading for interested physicians and physicists and for radiation dosimetrists.
Beamlet-based Treatment Plan Optimization in External Beam Radiation Therapy
Author: Ho Jin Kim
Publisher:
Published: 2014
Total Pages:
ISBN-13:
DOWNLOAD EBOOKExternal beam radiation therapy is one of the most widely used therapeutic methods for treating patients. In this modality, prior to the actual treatment, machine delivery parameters are optimized based on a patient model derived from the pre-treatment CT images. The goal of treatment planning is to maximize the dose to the planning target volume (PTV), while sparing the critical organs. A number of treatment techniques have been developed to meet the clinical demands. In reality, however, these techniques suffer from a series of problems and the performance of currently available plan optimization and dose delivery techniques is sub-optimal - the treatment plans out of the optimization algorithms are often not clinically sensible. Hence, considerable effort may be required to plan a patient's treatment, seriously hindering the optimal and efficient use of the radiation therapy. This thesis presents efficient and effective fluence-map optimizing techniques to demonstrate the improvement in either plan quality or delivery efficiency in static field and (continuous) rotational arc treatment schemes. To attain the objective above, new mathematical models and beam configurations are employed in the center of the treatment planning and its optimizing process. Of note, the demonstrations of our proposed methods or strategies proceed in two directions: (1) improving the delivery efficiency without damaging the plan quality, and (2) enhancing the plan quality, while maintaining the similar delivery efficiency of the existing methods.
Spatially Modulated Dose Optimization and Performance Limitations with Robust Targeting Performance for Preclinical Irradiation
Author: James Michael Patrick Stewart
Publisher:
Published: 2018
Total Pages:
ISBN-13:
DOWNLOAD EBOOKThe flexibility and sophistication of modern external beam radiotherapy treatment planning and delivery methods have advanced techniques to improve the therapeutic ratio. Contemporary dose optimization and calculation algorithms facilitate radiotherapy plans which closely conform the three-dimensional dose distribution to the target, with beam shaping devices and image guided field targeting ensuring the rigor and accuracy of treatment delivery. In general, such advances outpaced the technical ability of preclinical systems to faithfully reproduce the clinical capabilities at the scale required for robust small animal or radiobiological investigations. Evidence for sophisticated, and potentially efficacious, new clinical treatment strategies could not always be gathered from preclinical data owing to the improbability of rigorously scaling the proposed technique to the fidelity required for small animal studies. Within the past decade, several groups have developed dedicated small animal irradiator platforms to redress this imbalance. Such systems are commonly based on on-board computed tomography (CT) approaches to facilitate visualization and radiation targeting with interchangeable collimators incorporating field sizes on the millimeter scale. The integration of these capabilities has laid the foundation for precisely modulating and accurately targeting radiation dose for intricate preclinical studies, but algorithms and methods to do so remain in their infancy. In this thesis, we advance techniques to robustly optimize and accurately deliver spatially varying dose distributions for small animal or radiobiological research. An optimization framework based on empirically measured dose kernel measurements is first developed. The native targeting uncertainty of the microirradiator is then rigorously quantified and an online method to ensure high performance targeting accuracy for all radiation field sizes is demonstrated. Finally, it is proven that the underlying spatial frequency content of a dose kernel fundamentally limits the achievable degree of spatial modulation. This result is refined to define a lower bound in the minimization of a dose optimization objective function and provide a direct, analytic method to estimate the result of such an optimization. The combined results demonstrate that the optimization of complex dose distributions can be quickly estimated, iteratively refined, and automatically delivered with millimetre scale modulation at an accuracy of a tenth of a millimetre.
Optimization of External Radiation Beams for Therapy Planning
Author: Tom Lewis Gallagher
Publisher:
Published: 1967
Total Pages: 476
ISBN-13:
DOWNLOAD EBOOKOptimization Approaches for Planning External Beam Radiotherapy
Author: Halil Ozan Gozbasi
Publisher:
Published: 2010
Total Pages:
ISBN-13:
DOWNLOAD EBOOKExternal 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.
