IAEA-TECDOC-1223 Current status of neutron capture therapy May 2001 The originating Sections of this publication in the IAEA was: Applied Radiation Biology and Radiotherapy Section Dosimetry and Medical Radiation Physics Section Division of Human Health and the Physics Section Division of Physical and Chemical Sciences International Atomic Energy Agency Wagramer Strasse 5 P.O. Box 100 A-1400 Vienna, Austria CURRENT STATUS OF NEUTRON CAPTURE THERAPY IAEA, VIENNA, 2001 IAEA-TECDOC-1223 ISSN 1011–4289 © IAEA, 2001 Printed by the IAEA in Austria May 2001 FOREWORD There are about 6000 new glioblastoma multiform brain tumours diagnosed each year in the United States of America alone. This cancer is usually fatal within six months of diagnosis even with current standard treatments. Research on boron neutron capture therapy (BNCT) has been considered as a method of potentially curing such cancers. There is a great interest at under-utilised research reactors institutions to identify new medical utilization, attractive to the general public. Neutron capture therapy is a true multidisciplinary topic with a large variety of individuals involved. This publication attempts to provide current information for all those thinking about being involved with NCT, based on the knowledge and experience of those who have pioneered the treatment. It covers the whole range of NCT from designing reactor conversions or new facilities, through to clinical trials and their effectiveness. However, since most work has been done with boron capture therapy for brain tumours using modified thermal research reactors, this tends to be the focus of the report. One of the factors which need to be addressed at the beginning is the timing of the further development of NCT facilities. It should be emphasised that all current work is still at the research stage. Many of those now involved believe that there is little need for many more research facilities until such time as the treatment shows more promising results. For this and other reasons discussed in the report, very serious consideration should be given by research reactor owners and operators before spending large sums of money converting their facilities for NCT. Papers presented at the Technical Committee Meeting on Current Issues Related to Neutron Capture Therapy, held in Vienna from 14 to 18 June 1999, are given in the annexes. The contribution of the participants to the drafting of this publication is gratefully acknowledged. The consultant editorial group which significantly contributed to this publication comprised: D. Rorer of the Brookhaven National Laboratory, USA, A. Wambersie of the Université Catholique de Louvain, Belgium, G. Whitmore of the Ontario Cancer Institute, Princess Margret Hospital, Canada and R. Zamenhof of the Beth Israel Deaconess Medical Center, USA. The IAEA staff members responsible for the preparation of this publication were V. Levin and P. Andreo of the Division of Human Health and B. Dodd of the Division of Physical and Chemical Sciences. EDITORIAL NOTE In preparing this publication for press, staff of the IAEA have made up the pages from the original manuscript(s). The views expressed do not necessarily reflect those of the IAEA, the governments of the nominating Member States or the nominating organizations. Throughout the text names of Member States are retained as they were when the text was compiled. The use of particular designations of countries or territories does not imply any judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries. The mention of names of specific companies or products (whether or not indicated as registered) does not imply any intention to infringe proprietary rights, nor should it be construed as an endorsement or recommendation on the part of the IAEA. CONTENTS OVERVIEW ...............................................................................................................................1 1. DESIRED NEUTRON BEAM PARAMETERS....................................................................6 1.1. General beam properties..................................................................................................6 1.2. Epithermal beam intensity...............................................................................................7 1.3. Incident beam quality ......................................................................................................7 1.3.1. The fast neutron component..................................................................................8 1.3.2. The gamma ray component ...................................................................................8 1.3.3. The ratio between the thermal flux and the epithermal flux .................................8 1.3.4. The ratio between the total neutron current and the total neutron flux. ................8 1.4. Beam size ........................................................................................................................8 2. NEUTRON SOURCES FOR CAPTURE THERAPY...........................................................9 2.1. Possible sources of neutrons ...........................................................................................9 2.2. Converted thermal reactors using spectrum shifting and filtering ..................................9 2.3. Fast reactors.....................................................................................................................9 2.4. New reactor designs ........................................................................................................9 2.5. Fission converters..........................................................................................................10 2.6. Accelerators...................................................................................................................10 2.7. Californium ...................................................................................................................10 References to Section 2 ........................................................................................................12 3. REACTOR AND BEAM DESIGN CONSIDERATIONS...................................................13 3.1. Core reflector.................................................................................................................13 3.2. Spectrum shift vs. filtered beam....................................................................................13 3.3. Core-to-patient distance ................................................................................................13 3.4. Beam intensity and current-to-flux ratio .......................................................................14 3.5. Undesirable radiation components in the incident epithermal beam ............................15 3.5.1. Gamma contamination ........................................................................................15 3.5.2. Thermal neutron contamination ..........................................................................15 3.5.3. Fast neutron contamination .................................................................................16 3.6. Moderators ....................................................................................................................16 3.7. Filters.............................................................................................................................16 3.8. Collimators....................................................................................................................16 3.9. Shutters..........................................................................................................................17 3.10. Fission converters........................................................................................................17 3.11. Reactor beam design analysis......................................................................................18 3.12. Beam monitoring.........................................................................................................19 References to Section 3 ........................................................................................................20 4. IRRADIATION FACILITY OPERATION AND MANAGEMENT...................................21 4.1. Operation of the facility ................................................................................................21 4.1.1. Reliability............................................................................................................21 4.1.2. Availability..........................................................................................................21 4.1.3. Single versus multiple users................................................................................21 4.1.4. Continuous versus intermittent operations..........................................................21 4.2. Personnel at the NCT facility........................................................................................21 4.2.1. Staffing needs......................................................................................................22 4.2.2. Responsibilities ...................................................................................................22 4.3. Technical co-operation and communication .................................................................23 4.3.1. Between reactor operation