Volumetric modulated arc therapy for stereotactic body radiotherapy

136 Pages·2012·4.65 MB·English

Volumetric modulated arc therapy for stereotactic body radiotherapy:
Planning considerations, delivery accuracy and efficiency

Chin Loon Ong
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Volumetric modulated arc therapy for stereotactic body radiotherapy: Planning considerations, delivery accuracy and efficiency
________________________________________________________________________________________________________________

Volumetric modulated arc therapy for stereotactic body radiotherapy: Planning
considerations, delivery accuracy and efficiency

Nederlandse title:
Volumetrisch gemoduleerde arc therapie voor stereotactische radiotherapie: planning,
bestralingsnauwkeurigheid en efficiëntie

Thesis, Vrije Universiteit Amsterdam

© Chin Loon Ong, Amsterdam 2012
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means,
electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the copyright owner.

ISBN: 9789088914447

Address for correspondence:
Chin Loon Ong
Department of Radiation Oncology
VU University Medical Center
De boelelaan 1107
1081HV Amsterdam
Email: [email protected]
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VRIJE UNIVERSITEIT

Volumetric modulated arc therapy for stereotactic body radiotherapy:
Planning considerations, delivery accuracy and efficiency

ACADEMISCH PROEFSCHRIFT

ter verkrijging van de graad Doctor aan
de Vrije Universiteit Amsterdam,
op gezag van de rector magnificus
prof.dr. L.M. Bouter,
in het openbaar te verdedigen
ten overstaan van de promotiecommissie
van de Faculteit der Geneeskunde
op woensdag 19 september 2012 om 11.45 uur
in de aula van de universiteit,
De Boelelaan 1105

door

Chin Loon Ong

geboren te Maleisië

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Volumetric modulated arc therapy for stereotactic body radiotherapy: Planning considerations, delivery accuracy and efficiency
________________________________________________________________________________________________________________

promotoren: prof.dr. S. Senan
prof.dr. B.J. Slotman
copromotor: dr. W.F.A.R. Verbakel

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For my dearest family
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Volumetric modulated arc therapy for stereotactic body radiotherapy: Planning considerations, delivery accuracy and efficiency
________________________________________________________________________________________________________________

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Contents

Chapter 1 Introduction 9

Chapter 2 Stereotactic radiotherapy for peripheral lung tumors: A
27
comparison of volumetric modulated arc therapy with 3

other delivery techniques

Radiotherapy and Oncology December 2010;97(3):437-442

Chapter 3 Treatment of large stage I-II lung tumors using stereotactic
43
body radiotherapy (SBRT): planning consideration and early

toxicity

Radiotherapy and Oncology December 2010;97(3):431-436

Chapter 4 Dosimetric impact of interplay effect on RapidArc lung 59
stereotactic treatment delivery

International Journal of Radiation Oncology*Biology*Physics January 2011;79(1):305-

311

Chapter 5 Impact of the calculation resolution of anisotropic analytical
73
algorithm (AAA) for small fields and RapidArc treatment

plans

Medical Physics 2011;38(8):4471-4479

Chapter 6 Fast arc delivery for stereotactic body radiotherapy of 93
vertebral and lung tumors

International Journal of Radiation Oncology*Biology*Physics May 2012;83(1):e137-143

Chapter 7 Dosimetric impact of intra-fraction motion during high dose
107
rate stereotactic vertebral radiotherapy using flattened and

flattening filter free beams

Submitted

Chapter 8 Discussion

119

Appendices

Summary
136
Samenvatting
140
Acknowledgement
144
Curriculum Vitae
147
List of publications
148

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Volumetric modulated arc therapy for stereotactic body radiotherapy: Planning considerations, delivery accuracy and efficiency
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Chapter 1

Introduction

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Volumetric modulated arc therapy for stereotactic body radiotherapy: Planning considerations, delivery accuracy and efficiency
________________________________________________________________________________________________________________

1.1 Radiotherapy

According to the World Health Organization, cancer is the leading cause of death around the
world. In 2008, it was estimated that there were about 12.7 million new cancer cases and 7.6
million cancer deaths [1]. In the Netherlands alone, around 86,800 new cancer cases were
reported in 2007 and it is projected to rise to about 123,000 in 2020 [2]. Radiotherapy is one
of the main treatment options for cancer. The aim of radiotherapy is to destroy cancerous
cells while minimizing damage to the surrounding normal tissues. As normal tissues are able
to repair radiation damage better than cancer cells, a certain amount of dose delivered in
multiple fractions can effectively kill cancer cells, while sparing normal tissues. This
technique has been used as a cancer treatment by Emiel Grubbe [3] soon after the discovery
of X-rays by Wilhelm Röntgen in 1895 [4]. Since then, the art of radiation delivery has
evolved through the ages. Radiation therapy was traditionally delivered using radioactive
elements such as radium-226, which produces photons in the form of gamma rays at an
average energy of 0.83 MeV. In mid 1900s, radium was replaced by cobalt-60 in cancer
treatment due to its higher gamma ray energies (1.17 and 1.33 MeV). The first external beam
radiotherapy unit using Cobalt-60 was installed in 1951. It was widely adopted since x-ray
generators were only capable of generating x-rays at voltages up to 300 KV at that period.

The use of x-ray generators took a major step forward in 1953 when the first medical linear
accelerator (linac) which could generate X-rays up to 8MV became available [5]. Although
the maximum X-ray energy is 8 MeV for an 8MV X-ray beam, the mean energy was much
lower, in the order of approximately 3 MeV. The megavoltage linac had the advantages of
generating a higher penetrating energy, higher dose rate, lack of a physical radiation source
and better capability of delivering a uniform dose. Although the initial linacs did not have a
gantry that could rotate around the patient, in 1960, the first full rotational isocentric linac
was released. Despite the evident advantages of linacs, Cobalt-60 units were still widely used
because of the low cost of these machines. As technology advanced, the design of the linac
was simplified and the cost was reduced to be competitive with the Cobalt-60 units. In
subsequent decades, linacs began to replace Co-60 unit and have now become the standard in
external beam radiation therapy treatment.

Conventional radiotherapy delivery commonly uses the combination of two or more open
fields. Parallel opposed fields (Fig. 1a) is the simplest technique [6], and it is still being used
for fast treatment planning and delivery, mainly for palliative treatments [7,8]. Among the
advantages of parallel opposed fields are simplicity, less chance of geometric miss and
homogenous dose to the target volume (Fig. 2a). However, the latter is depending on the
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