Comprehensive Brachytherapy: Physical and Clinical Aspects PDF

Preface

Comprehensive Brachytherapy: Physical and Clinical Aspects is the most comprehensive overview available for the field of brachytherapy, covering fundamental principles of brachytherapy, modern clinical practice, and major advances under development.

Its concept is challenging as it brings together in one volume the technological basis, radiation dosimetry, quality assurance, and fundamentals of brachytherapy. In addition, it presents reviews of the most recent clinical practice in brachytherapy including prostate, gynecology, breast, and other clinical treatment sites. Brachytherapy is a field where the physicist and clinicians work together very closely, often in the same operating room. This book provides insight into the roles of these respective specialties and their collaboration, which provides an excellent treatment approach for the patients.

Modern brachytherapy is a mature treatment modality in several different perspectives embracing the use of standard equipment together with the application of advanced clinical imaging facilities, understanding of radiobiological effects on different tissues, and widely available and uniformly accepted principles of physics and dosimetry techniques and protocols. This treatment modality may be performed using either seed-type sources for permanent implantations or miniaturized stepping source technology for temporary implants with high-, pulsed-, and lowdose- rate 192Ir sources. The indication for brachytherapy in cervical cancer is unchallenged, and major developments have been reported for treatments in other sites such as prostate and breast.

Until now, treatment planning systems have been based on the assumption that tissue heterogeneity, applicator, and intersource effects are negligible, and thus, a water phantom dosimetry was used for patient dosimetric planning. However, it is now clear that they do introduce uncertainties in the treatment planning process, and new algorithms have been developed to account for them. Alongside this change, new types of applicators have been developed; these applicators are CT or MR compatible, thereby reducing the artifacts from the images. They are also more versatile and allow for asymmetric and individualized dose distributions. The wide availability of ultrasound, CT, and MRI scanners in modern radiation therapy departments plays a key role in these developments and has given impetus to three-dimensional imaging as a gold standard for target delineation, implant reconstruction, and dose prescription. In addition, in the near future, functional and molecular imaging provided by multiparametric MR imaging and PET-CT or PET-MR imaging devices will support biology-driven instead of morphology-driven target delineation leading to individualized biology-based treatment planning and treatment delivery.

Several other important areas relating to brachytherapy are presented in this book. The radiobiology chapter brings together the modern mathematics and the biological fundamentals, as applicable in the brachytherapy domain. There is a clear summary provided on the uncertainties associated with the brachytherapy dose administration with an in-depth discussion of the physics of uncertainties exploring a number of examples. Another chapter presents the clinical uncertainties in brachytherapy, focusing on variation of parameters such as contouring, image reconstruction, interfraction and intrafraction movement, etc. These observations also lead to better insight into the concept of applying margins in brachytherapy, challenging the old paradigm of considering a brachytherapy clinical target volume equal to the planning target volume. Clear views and practical data on radiation protection are also provided as a separate chapter.

Another section looks ahead to emerging technologies in brachytherapy and reviews why and how they should be employed. These chapters address new modalities added to the field of brachytherapy, including (1) the use of small electronic photon-emitting sources instead of using radioactivity; (2) the use of radioactive microspheres to treat metastatic tumors and hepatocellular carcinoma; (3) the application of neutron sources; (4) the development of robotics and navigation systems to refine the implant procedures; (5) 60Co HDR source; and (6) 169Yb and probably 170Tm miniaturized stepping sources for afterloading technology.

After these technological discussions, a vision is presented on the use of prospective risk analysis methods for the introduction of new brachytherapy techniques. Independent validation of the organization of the department and the technical and clinical procedures therein are discussed in an overview chapter on quality control and audits. The necessity of proper training of the teams, for the best implementation of the new applicators and treatment modalities, is shown in the final chapter with an overview of activities in several national and international professional societies.

Authors for the chapters were deliberately chosen to represent brachytherapy practices from different continents and to have the perspective of those directly involved in this practice. In most cases, authorships were shared between experts from North America and the European continent. In this way, the editors have tried to bring together as much as possible different views and approaches, aiming at a complete overview of best brachytherapy practices, in the hopes that this book will gain value for practitioners worldwide.

Recommendations may change in the future with the availability of more clinical, physical, dosimetric, and technological data. However, we believe that the material presented in the book defines the basis of modern brachytherapy, and we are confident that it will remain useful for our readers in the future.