The physics of conformal radiotherapy : advances in technology

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THE PHYSICS OF CONFORMAL RADIOTHERAPY: Advance in Technology......Page 2
CONTENTS......Page 6
PREFACE......Page 11
ACKNOWLEDGEMENTS......Page 16
1.1. THE RATIONALE FOR DEVELOPING CONFORMAL THERAPY......Page 18
Table of Contents......Page 0
1.2. METHODS FOR AND CONTROVERSIES IN DETERMINING THE CONTOURS OF TARGET VOLUMES, ORGANS-AT-RISK AND THEIR BEAM’S-EYE-VIEW PROJECTIONS......Page 21
1.2.1. The interaction with the human observer......Page 23
1.2.2. The influence of organ movement......Page 24
1.2.3. Setup errors......Page 27
1.2.4. The use of multiple-modality imaging......Page 28
1.2.5. Beam apertures......Page 30
1.3.1. What is treatment-plan optimisation?......Page 31
1.3.2. Classes of inverse-treatment-planning techniques......Page 33
1.3.3.1. A simple analogy of a walker descending from a hilltop to the lowest poim point a valley.......Page 35
1.3.3.3. General mathematical description of the optimisation problem and simulated annealing.......Page 37
1.3.3.4. The hill descender’s problem in mathematical terms.......Page 38
1.3.3.5. IMB optimisation by simulated annealing.......Page 39
1.3.4. The power of simulated annealing: cost functions......Page 42
1.3.5. Classical and fast simulated annealing......Page 46
1.3.6. Practicalities of implementing simulated annealing for inverse treatment planning......Page 47
1.3.7. Implementations at the Institute of Cancer Research (ICR) and Royal Marsden NHS Trust (RMNHST)......Page 49
1.3.8. Conclusion......Page 53
1.4. PROGRESS IN 3D TREATMENT-PLAN OPTIMISATION BY SIMULATED ANNEALING AT MEMORIAL SLOAN KETTERING HOSPITAL (MSK), NEW YORK......Page 54
1.5. OPTIMISATION AT DELFT UNIVERSITY OF TECHNOLOGY......Page 57
1.6. PROJECTION AND BACKPROJECTION ISSUES IN ANALYTIC INVERSE TREATMENT PLANNING FOR OPTIMISING IMBS......Page 58
1.7. DOSE CALCULATION FOR INVERSE PLANNING OF IMBS......Page 62
1.8. DETERMINISTIC ITERATIVE OPTIMISATION OF IMBS: HOLMES’ SOLUTION......Page 64
1.9. DETERMINISTIC ITERATIVE OPTIMISATION OF IMBS: BORTFIELD'S SOLUTION......Page 67
1.10. OPTIMISATION USING IMBS, A BIOLOGICAL COST FUNCTION AND ITERATIVE TECHNIQUES......Page 72
1.11. OPTIMISATION OF 2D PLANNING OF IMBS BY MINIUM NOR, MAXIMUM ENTROPY AND GENETIC METHODS......Page 77
1.12. ITERATIVE OPTIMISATION OF IMBS AT THE UNIVERSITY OF WISCONSIN; THE POWER OF COST FUNCTIONS AND AN ELECTROSTATIC ANALOGY......Page 79
1.13. OPTIMISATION OF DYNAMIC THERAPY......Page 81
1.14. OPTIMISATION OF BEAM ORIENTATIONS......Page 82
1.15. SHEROUSE'S METHOD FOR COMBINING WEGED FIELDS BY ANALYSIS OF GRADIENTS......Page 87
1.16. CONTROVERSIES IN DETERMINING THE ‘BEST PLAN’......Page 92
1.17. SUMMARY......Page 93
REFERENCES......Page 94
CHAPTER 2: METHODS TO CREATE INTENSITY-MODULATED BEAMS (IMBS)......Page 113
2.1. CLASS 1: 2D COMPENSATORS......Page 114
2.2. CLASS 2: DYNAMIC-LEAF COLLIMATION......Page 116
2.2.1. The solution of Convery and Rosenbloom......Page 118
2.2.2. The solution of Svensson et al......Page 120
2.2.3. The solution of Stein et al......Page 123
2.2.4. The solution of Spirou and Chui......Page 127
2.2.5.1. Dynamic-leaf movement.......Page 132
2.2.5.2. Intensity-modulated arc therapy.......Page 139
2.2.6. Iterative optimisation of scanning-leaf configurations......Page 141
2.2.7. The solution of Spirou and Chui including upstream influence modulation......Page 142
2.2.8. Experimental delivery of IMBs with dynamic-leaf movement......Page 144
2.3. CLASS 3: LEAF-SWEEP AND CLOSE-IN; THE BORTFELD AND BOYER METHOD OF MULTIPLE-SEGMENTED (STATIC) IMBS......Page 147
2.4. CLASS 4: TOMOTHERAPY; THE CAROL COLLIMATOR AND THE MACKIE MACHINE......Page 155
2.4.1.The NOMOS 2D intensity-modulating collimator......Page 169
2.4.2. A diagnostic analogue......Page 172
2.5. CLASS 5 : CREATION OF IMBS BY THE MOVING-BAR TECHNIQUE......Page 173
2.7. SCANNING-BEAM THERAPY......Page 179
2.8. VERIFICATION OF IMB DELIVERY......Page 182
2.9. SUMMARY......Page 183
REFERENCES......Page 184
CHAPTER 3: THE MULTILEAF COLLIMATOR (MLC) IN CLINICAL PRACTICE......Page 193
3.1. CHARACTERISING THE PHYSICAL PROPERTIES OF AN MLC......Page 194
3.2. CAN AN MLC REPLACE SHAPED CAST BLOCKS?......Page 203
3.2.1. Setting leaves with respect to the beam’s-eye-view of the PTV......Page 209
3.2.2. Does the use of the MLC save time?......Page 212
3.3.1. The MLC creating multiple fields for conformal therapy......Page 214
3.3.3. The MLC in conformal stereotactic radiotherapy......Page 215
3.3.4. Sparing dose to normal brain tissue with shaped fields......Page 218
3.3.5. Theoretical studies of normal-tissue sparing in stereotactic radiotherapy using various field-shaping collimators......Page 219
3.4. COMPUTER CONTROL OF MLC LEAVES AND INTERFACE TO IMAGING......Page 224
3.5. VERIFYING MLC LEAF POSITION......Page 225
3.6.1. The GEMS MLC......Page 226
3.6.2. A prototype multi-rod MLC......Page 228
REFERENCES......Page 231
4.1. THE USE OF PORTAL IMAGES TO ASSESS AND CORRECT PATIENT SETUP ERROR......Page 238
4.1.1. The use of radio-opaque markers for patient (re)positioning......Page 240
4.2. TRANSIT DOSIMETRY......Page 241
4.2.1. The digital reconstructed radiograph (DRR)......Page 242
4.2.2. Registration of the DRR with the portal image; creation of treatment-time 3D CT data......Page 244
4.2.3.1. Detector calibration.......Page 245
4.2.3.2. Extraction of primary exit fluence.......Page 251
4.2.4. Backprojection to obtain a 3D map of the primary fluence in the patient......Page 255
4.2.6. Determination of the 3D dose distribution......Page 256
4.2.7. Verification of verification, MRI of dose-sensitive gels......Page 258
4.2.7.1. PET imaging for verifying proton irradiations.......Page 261
4.3. USE OF PORTAL IMAGING FOR COMPENSATOR CONSTRUCTION......Page 262
REFERENCES......Page 266
5.1. TUMOUR CONTROL PROBABILITY: GENERAL CONSIDERATIONS......Page 275
5.2. MODELS FOR TCP WITH INTER- AND INTRA-TUMOUR HETEROGENEITY......Page 276
5.3. MECHANISTIC PREDICTION OF TCP......Page 280
5.4. DVH REDUCTION TECHNIQUES AND FORMULAE FOR COMPUTATION OF NTCP......Page 283
5.4.1.Equivalence of the Lyman expression and the Logistic formula for  NTCP......Page 289
5.5.1. Homogeneous irradiation......Page 290
5.5.2. Inhomogeneous irradiation......Page 294
5.6. RANKING 3D TREATMENT PLANS USING PROXY ATTRIBUTES......Page 296
5.7. ERROR ESTIMATION IN DETERMINING DVH, TCP AND NTCP......Page 297
5.8. CONTROVERSIES CONCERNING REPORTING VOLUMES......Page 300
5.9. SUMMARY......Page 301
REFERENCES......Page 302
6.1. NEW FACILITIES......Page 305
6.2. THE CLATTERBRIDGE FACILITY IN THE UK......Page 311
6.3. THE CLINICAL PROTON FACILITY AT LOMA LINDA, USA......Page 314
6.4. THE CLINICAL PROTON FACILITY AT ORSAY, PARIS, FRANCE......Page 316
6.5. THE CLINICAL PROTON FACILITY AT PSI, SWITZERLAND......Page 317
6.6. THE CLINICAL PROTON FACILITY AT FAURE, SOUTH AFRICA......Page 319
6.7. THE CLINICAL PROTON FACILITY AT INDIANA UNIVERSITY, USA......Page 322
6.9. THE CLINICAL PROTON FACILITY AT TRIUMF, CANADA......Page 323
6.10. THE PROPOSED UK HIGH-ENERGY PROTON FACILITY......Page 324
6.11.1. Physical description......Page 325
6.11.2. Clinical comparison......Page 326
6.11.3. Treatment planning for spot scanning......Page 327
6.12. PHOTONS OR PROTONS?......Page 328
6.13. PROTON RADIOGRAPHY......Page 330
6.14. SUMMARY......Page 331
REFERENCES......Page 332
7.1. TOMOGRAPHY ‘DRIVES’ CONFORMAL RADIOTHERAPY......Page 339
7.2. CROSS SECTION IMAGING ON A RADIOTHERAPY SIMULATOR......Page 340
7.3. MULTIMODALITY IMAGING AND IMAGE COMPRESSION......Page 348
7.4. 3D DISPLAY OF ANATOMY AND RADIATION QUANTITIES......Page 350
7.4.1. ‘Tumour’s-eye-view......Page 358
7.5. THE CT-SIMULATOR......Page 359
7.6. INFORMATION COORDINATION......Page 362
7.7. THERAPY COMPUTATIONAL ADVANCES THAT ASSIST RADIATION......Page 363
7.8. SUMMARY......Page 364
REFERENCES......Page 365
EPILOGUE......Page 370
APPENDIX A: DECISION TREES IN CONFORMAL TREATMENT PLANNING......Page 372
APPENDIX B: METHODS OF COMPUTING DOSE TO A POINT AND FEATURES OF EACH METHOD......Page 375
APPENDIX C: QUALITY ASSURANCE OF CONFORMAL THERAPY......Page 378
APPENDIX D: A NOTE ON THE WORK OF GEORGE BIRKHOFF......Page 381
REFERENCES......Page 383