Incorporating Uncertainty and Motion in Intensity Modulated Radiation Therapy Treatment Planning PDF Download
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Author: Benjamin Charles Martin
Publisher:
ISBN:
Category :
Languages : en
Pages : 264
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Book Description
Abstract: In radiation therapy, one seeks to destroy a tumor while minimizing the damage to surrounding healthy tissue. Intensity Modulated Radiation Therapy (IMRT) uses overlapping beams of x-rays that add up to a high dose within the target and a lower dose in the surrounding healthy tissue. IMRT relies on optimization techniques to create high quality treatments. Unfortunately, the possible conformality is limited by the need to ensure coverage even if there is organ movement or deformation. Currently, margins are added around the tumor to ensure coverage based on an assumed motion range. This approach does not ensure high quality treatments. In the standard IMRT optimization problem, an objective function measures the deviation of the dose from the clinical goals. The optimization then finds the beamlet intensities that minimize the objective function. When modeling uncertainty, the dose delivered from a given set of beamlet intensities is a random variable. Thus the objective function is also a random variable. In our stochastic formulation we minimize the expected value of this objective function. We developed a problem formulation that is both flexible and fast enough for use on real clinical cases. While working on accelerating the stochastic optimization, we developed a technique of voxel sampling. Voxel sampling is a randomized algorithms approach to a steepest descent problem based on estimating the gradient by only calculating the dose to a fraction of the voxels within the patient. When combined with an automatic sampling rate adaptation technique, voxel sampling produced an order of magnitude speed up in IMRT optimization. We also develop extensions of our results to Intensity Modulated Proton Therapy (IMPT). Due to the physics of proton beams the stochastic formulation yields visibly different and better plans than normal optimization. The results of our research have been incorporated into a software package OPT4D, which is an IMRT and IMPT optimization tool that we developed.
Author: Benjamin Charles Martin
Publisher:
ISBN:
Category :
Languages : en
Pages : 264
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Book Description
Abstract: In radiation therapy, one seeks to destroy a tumor while minimizing the damage to surrounding healthy tissue. Intensity Modulated Radiation Therapy (IMRT) uses overlapping beams of x-rays that add up to a high dose within the target and a lower dose in the surrounding healthy tissue. IMRT relies on optimization techniques to create high quality treatments. Unfortunately, the possible conformality is limited by the need to ensure coverage even if there is organ movement or deformation. Currently, margins are added around the tumor to ensure coverage based on an assumed motion range. This approach does not ensure high quality treatments. In the standard IMRT optimization problem, an objective function measures the deviation of the dose from the clinical goals. The optimization then finds the beamlet intensities that minimize the objective function. When modeling uncertainty, the dose delivered from a given set of beamlet intensities is a random variable. Thus the objective function is also a random variable. In our stochastic formulation we minimize the expected value of this objective function. We developed a problem formulation that is both flexible and fast enough for use on real clinical cases. While working on accelerating the stochastic optimization, we developed a technique of voxel sampling. Voxel sampling is a randomized algorithms approach to a steepest descent problem based on estimating the gradient by only calculating the dose to a fraction of the voxels within the patient. When combined with an automatic sampling rate adaptation technique, voxel sampling produced an order of magnitude speed up in IMRT optimization. We also develop extensions of our results to Intensity Modulated Proton Therapy (IMPT). Due to the physics of proton beams the stochastic formulation yields visibly different and better plans than normal optimization. The results of our research have been incorporated into a software package OPT4D, which is an IMRT and IMPT optimization tool that we developed.
Author: Ehsan Salari
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
ABSTRACT: My Ph. D. dissertation focuses on model and algorithm development to enhance several aspects of an IMRT treatment plan. In particular, it addresses two major clinical issues encountered in treatment delivery, which are efficiency and accuracy. The beam-on-time, as a measure of the delivery efficiency, is incorporated into the IMRT treatment planning problem using a Direct Aperture Optimization approach. This allows for taking the efficiency factor into consideration when designing a treatment plan. Moreover, we have proposed robust and efficient models and solution approaches to account for the dosimetric inaccuracies caused during the treatment delivery. More specifically, we have considered two sources of inaccuracy which may compromise the treatment outcome; (1) the tongue-and-groove effect and (2) the organ motion. To account for the tongue-and-groove effect, we have developed robust models and efficient solution methods to obtain clinically-attractive treatment plans regardless of the exact effect of this source of inaccuracy. Furthermore, to incorporate the uncertainty caused by the organ motion into the IMRT treatment planning problem, we have proposed an entirely new modeling framework as well as solution approaches to obtain high-quality treatment plans while taking the variation of the treatment outcome into account.
Author: Runqing Jiang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Yelin Suh
Publisher:
ISBN:
Category : Lungs
Languages : en
Pages :
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Book Description
Lung cancer is the leading cause of cancer-related deaths worldwide. Radiotherapy is one of the main treatment modalities of lung cancer. However, the achievable accuracy of radiotherapy treatment is limited for lung-based tumors due to respiratory motion. Four-dimensional radiotherapy explicitly accounts for anatomic motion by characterizing the motion, creating a treatment plan that accounts for this motion, and delivering this plan to the moving anatomy. This thesis focuses on the current problems and solutions throughout the course of four-dimensional radiotherapy. For characterization of respiratory-induced motion, patient tumor motion data were analyzed. It is shown that tumor motion can be significant during radiotherapy treatment, and its extent, direction, and linearity vary considerably between patients, between treatment fractions, and between respiratory cycles. After this, approaches to four-dimensional intensity-modulated radiation therapy treatment planning were developed and investigated. Among the techniques to manage respiratory motion, tumor tracking using a dynamic multileaf collimator delivery technique was chosen as a promising method. A formalism to solve a general four-dimensional intensity-modulated radiation therapy treatment-planning problem was developed. Specific solutions to this problem accounting for tumor motion initially in one dimension and extending this to three dimensions were developed and investigated using four-dimensional computed tomography planning scans of lung cancer patients. For four-dimensional radiotherapy treatment delivery, accuracy of two-dimensional projection imaging methods was investigated. Geometric uncertainty due to the limitation of two-dimensional imaging in monitoring three-dimensional tumor motion during treatment delivery was quantified. This geometric uncertainty can be used to estimate proper margins when a single two-dimensional projection imager is used for four-dimensional treatment delivery. Lastly, tumor-tracking delivery using a moving average algorithm was investigated as an alternative delivery technique that reduces mechanical motion constraints of a multileaf collimator. Moving average tracking provides an approximate solution that can be immediately implemented for delivery of four-dimensional intensity-modulated radiation therapy treatment. The clinical implementation of four-dimensional guidance, intensity-modulated radiation therapy treatment planning, and dynamic multileaf collimator tracking delivery may have a positive impact on the treatment of lung cancer.
Author: Nancy Y. Lee
Publisher: Springer
ISBN: 3319424785
Category : Medical
Languages : en
Pages : 393
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Book Description
This handbook is designed to enable radiation oncologists to treat patients appropriately and confidently by means of particle therapy. The orientation and purpose are entirely practical, in that the focus is on the physics essentials of delivery and treatment planning , illustration of the clinical target volume (CTV) and associated treatment planning for each major malignancy when using particle therapy, proton therapy in particular. Disease-specific chapters provide guidelines and concise knowledge on CTV selection and delineation and identify aspects that require the exercise of caution during treatment planning. The treatment planning techniques unique to proton therapy for each disease site are clearly described, covering beam orientation, matching/patching field techniques, robustness planning, robustness plan evaluation, etc. The published data on the use of particle therapy for a given disease site are also concisely reported. In addition to fully meeting the needs of radiation oncologists, this "know why" and “know how” guide to particle therapy will be valuable for medical physicists, dosimetrists, and radiation therapists.
Author:
Publisher: Medical Physics Publishing Corporation
ISBN:
Category : Medical
Languages : en
Pages : 464
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Book Description
Provides an account of the perspective, methodology, and experience in the physical and medical aspects of IMRT at Memorial Sloan-Kettering Cancer Center (MSKCC).
Author: Indra J Das
Publisher: Myprint
ISBN: 9780750317696
Category :
Languages : en
Pages : 360
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Book Description
Author: Arvind Kumar
Publisher:
ISBN:
Category : Mathematical optimization
Languages : en
Pages :
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Book Description
We have proposed a new formulation that incorporates all aspects which control the quality of a treatment plan that have been considered to date. However, in contrast with established mixed-integer and global optimization formulations, we do so while retaining linearity of the optimization problem, and thereby ensuring that the problem can be solved efficiently. We also developed a linear programming based algorithm to integrate beam orientation optimization with intensity modulation. We have developed neighborhood search methods based on fast sensitivity analysis and greedy search based heuristics for solving this integrated problem. Delivering complex dose distributions sometimes requires a set of very complex beam cross sections (fluence profiles).
Author: X. Allen Li
Publisher: CRC Press
ISBN: 1439816352
Category : Medical
Languages : en
Pages : 404
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Book Description
Modern medical imaging and radiation therapy technologies are so complex and computer driven that it is difficult for physicians and technologists to know exactly what is happening at the point-of-care. Medical physicists responsible for filling this gap in knowledge must stay abreast of the latest advances at the intersection of medical imaging an
Author: Todd Pawlicki
Publisher: John Wiley & Sons
ISBN: 0470376511
Category : Medical
Languages : en
Pages : 365
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Book Description
The publication of this fourth edition, more than ten years on from the publication of Radiation Therapy Physics third edition, provides a comprehensive and valuable update to the educational offerings in this field. Led by a new team of highly esteemed authors, building on Dr Hendee’s tradition, Hendee’s Radiation Therapy Physics offers a succinctly written, fully modernised update. Radiation physics has undergone many changes in the past ten years: intensity-modulated radiation therapy (IMRT) has become a routine method of radiation treatment delivery, digital imaging has replaced film-screen imaging for localization and verification, image-guided radiation therapy (IGRT) is frequently used, in many centers proton therapy has become a viable mode of radiation therapy, new approaches have been introduced to radiation therapy quality assurance and safety that focus more on process analysis rather than specific performance testing, and the explosion in patient-and machine-related data has necessitated an increased awareness of the role of informatics in radiation therapy. As such, this edition reflects the huge advances made over the last ten years. This book: Provides state of the art content throughout Contains four brand new chapters; image-guided therapy, proton radiation therapy, radiation therapy informatics, and quality and safety improvement Fully revised and expanded imaging chapter discusses the increased role of digital imaging and computed tomography (CT) simulation The chapter on quality and safety contains content in support of new residency training requirements Includes problem and answer sets for self-test This edition is essential reading for radiation oncologists in training, students of medical physics, medical dosimetry, and anyone interested in radiation therapy physics, quality, and safety.
