Radiotherapy Treatment Planning: New System Approaches

ISBN-13: 9781447112105 / Angielski / Miękka / 2012 / 220 str.

Olivier C. Haas; Olivier C. Haas

Opis

An in depth examination of many of the complex issues associated with planning and optimisation of intensity modulated radiotherapy treatment. It includes: a presentation of current practice, techniques and equipment used by medical physicists and others to deliver radiotherapy treatment; a systems modelling approach in the formulation of a beam model for optimisation, describing the effect of X-rays on human body tissues; a deterministic approach to the inverse problem in radiotherapy, based on weighted iterative least squares is modified to allow an adaptive scaling of the error to improve the performance of a general least squares algorithm; a guided random search methodology, based on genetic algorithms which is aimed at solving multi-objective optimisation problems is developed to optimise beam weight/wedge angle as well as coplanar beam orientation; the overall approach developed is demons trated practically using both traditional and modern measurement techniques.

Spis treści

1. Introduction and Brief Review of Developments in Radiotherapy.- 1.1 Introduction.- 1.2 Historical Review of Developments in Radiotherapy.- 1.2.1 The Early Workers.- 1.2.2 Effect of Radiation on Human Tissues.- 1.2.3 Improving the Physical Selectivity of Treatments.- 1.2.4 Developments of Megavoltage X-ray Machines.- 1.3 Radiotherapy Treatment Planning Procedures.- 1.3.1 Conventional Radiotherapy Procedures.- 1.3.2 Radiotherapy Treatment Planning.- 1.3.3 Automated Treatment Planning: Review of the Developments.- 1.3.4 Beam Compensation Techniques.- 1.4 Background to the Optimisation of Radiotherapy Treatment Plans.- 1.4.1 Traditional Approach to Manual Optimisation.- 1.4.2 Consideration of Region of Interest.- 1.4.3 Notion of Objective Function.- 1.4.4 Objective Based Dose Criteria.- 1.5 Optimisation in Radiotherapy: A Brief Review.- 1.5.1 Optimisation of Coplanar Beam Orientation.- 1.5.2 Optimisation of Beam Weight and Wedge Angle.- 1.5.3 Optimisation Method for in Field Intensity Modulation.- 1.5.4 Need for a Matrix Based Beam Model.- 1.5.5 Proposed Hybrid Approach.- 1.6 Concluding remarks.- 2. Beam Characteristics and Preliminary Modelling Considerations.- 2.1 Introduction.- 2.2 Need for an Appropriate Model Structure.- 2.3 Preliminary Physical Consideration.- 2.4 Typical Beam Characteristics.- 2.4.1 Photon Beam Central Axis Characteristics.- 2.4.2 In-Air-Profile.- 2.4.3 The Penumbra.- 2.4.4 Interaction of Photons with Matter.- 2.4.5 Influence of Inhomogeneities.- 2.5 Concept of Primary Modelling and Scatter Phenomenon.- 2.5.1 Primary Component.- 2.5.2 Forward Scatter Phenomenon.- 2.5.3 Determination of the Coefficient ?.- 2.6 Concluding Remarks.- 3. Formulation of Matrix Based Beam Model.- 3.1 Introduction.- 3.2 Parallel Pencil Beam Model Formulation.- 3.2.1 The Parallel Matrix Grid.- 3.2.2 Beam Dose Matrix.- 3.2.3 Primary Dose Calculation Matrix.- 3.2.4 Scatter Dose Calculation Matrix.- 3.3 Divergent Pencil Beam Matrix Formulation.- 3.3.1 Divergent Pencil Beam Matrix Grid.- 3.3.2 Overall Divergent Dose Calculation Matrix.- 3.4 Inclusion of In-Air-Profile, Penumbra and Patient Contour Correction.- 3.4.1 Inclusion of IAP.- 3.4.2 Inclusion of Patient Contour Correction.- 3.4.3 Inclusion of the Penumbra.- 3.4.4 General Formulation of the Matrix Based Beam Model.- 3.5 Verification and Tuning of Developed Beam Model.- 3.5.1 Open Field Tests.- 3.5.2 Intensity Modulated Beams.- 3.6 Concluding Remarks.- 4. Solving the Inverse Problem in Radiotherapy Treatment Planning.- 4.1 Introduction.- 4.2 Definition of the Inverse Problem.- 4.2.1 Brief Review of Previous Approaches.- 4.2.2 Inverse Problem — Preliminaries.- 4.3 Formulating the Inverse Problem for Matrix Based Beam Model.- 4.3.1 Derivation of ILS for a Single Beam.- 4.3.2 Multiple Beam Formulation.- 4.3.3 Assessment of the ILS Algorithm on Standard Test Cases.- 4.3.4 Introduction of Constraints on the IMBs.- 4.4 Articulation of the Objectives.- 4.4.1 Weighted Sum of the Objectives.- 4.4.2 Adaptive Objective Weighting.- 4.5 Improving the Rate of Convergence of the Algorithm.- 4.6 Simulation Studies.- 4.6.1 Influence of the Initial Conditions.- 4.6.2 Compensating for Inhomogeneities.- 4.7 Concluding remarks.- 5. Hybrid Genetic Algorithms Applied to Radiotherapy Treatment Planning.- 5.1 Introduction.- 5.1.1 Guided Random Search.- 5.2 Genetic Algorithms.- 5.2.1 Simple GA.- 5.2.2 Hybridising GAs.- 5.2.3 Multi-Objective Approach.- 5.3 Multi-Objective Genetic Algorithms.- 5.3.1 Pareto Ranking.- 5.3.2 Selection Methods.- 5.3.3 Diagramatic Representation.- 5.4 Optimisation of Coplanar Beam Orientation in Radiotherapy.- 5.4.1 Brief Review of Existing Approaches — Orientation.- 5.4.2 Motivation for the Geometrical Approach.- 5.4.3 Geometrical Formulation: Preliminaries.- 5.4.4 Formulation of the Objectives — Orientation.- 5.4.5 Coding Considerations — Orientation.- 5.4.6 Hybridisation by Inclusion of Problem Specific Search Operators.- 5.4.7 Simulation Studies — Beam Orientation..- 5.4.8 Influence of Optimal Beam Orientation on Dose Distribution.- 5.5 Optimisation of Beam Weights and Wedge Angles.- 5.5.1 Brief Review of Existing Techniques.- 5.5.2 Coding Strategies.- 5.5.3 Simulation Studies.- 5.6 Concluding Remarks.- 6. Experimental Verification of Overall Approach.- 6.1 Introduction.- 6.2 Optimisation of Conformal Radiotherapy Treatment.- 6.3 Modulating Beam Intensity with Compensators.- 6.3.1 Compensator Preliminaries.- 6.3.2 Modelling of the Compensators.- 6.3.3 Manufacture of the Compensators.- 6.3.4 Determination of the Number of Monitor Units.- 6.3.5 Schematic Representation of the Overall Approach.- 6.4 Experimental Verification of Intensity Modulated Radiation Therapy.- 6.4.1 Assessing Dose Distribution with Film.- 6.4.2 Assessment of Conformal Distribution with Gel Dosimeters.- 6.4.3 Overall Assessment of the Experiment.- 6.5 Concluding remarks.- 7. Conclusions.- References.

Blurb

This volume contains an in depth examination of many of the complex issues associated with planning and optimisation of intensity modulated radiotherapy treatment.

The book is divided into five parts: a presentation of current practice, techniques and equipment used by medical physicists and others to deliver radiotherapy treatment; a systems modelling approach is used in the formulation of a beam model for the purpose of optimisation, describing the effect of X-rays on human body tissues whilst taking all the relevant factors into account; a deterministic approach to the inverse problem in radiotherapy, based on weighted iterative least squares is modified to allow an adaptive scaling of the error to improve the performance of a general least squares algorithm; a guided random search methodology, based on genetic algorithms which is specifically aimed at solving multi-objective optimisation problems is developed to optimise beam weight/wedge angle as well as coplanar beam orientation; the overall approach developed is demonstrated practically using both traditional and modern measurement techniques such as film and more modern techniques such as gel dosimeter.

The work is essential for all those involved in the broad area of medical engineering, and will be an invaluable addition to libraries, institutions and for students of the subject at all levels.

 

Advances in Industrial Control aims to report and encourage the transfer of technology in control engineering. The rapid development of control technology has an impact on all areas of the control discipline. The series offers an opportunity for researchers to present an extended exposition of new work in all aspects of industrial control.