Proceedings of a Conference on Neutrons from Electron Medical Accelerators

194 Pages·2014·9.55 MB·English

by  Heaton, H. T

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1
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Proceedings of a Conference
^^jo^
on Neutrons from Electron m
:;n
Medical Accelerators
Proceedings of a Conference held at the National Bureau of Standards, C-
Gaithersburg, Maryland, April 9-10, 1979
Edited by:
H.T. Heaton,
II
National Measurement Laboratory
National Bureau of Standards
Washington, DC 20234
R. Jacobs
Bureau of Radiological Health
Food and Drug Administration
Rockville, Maryland 20857
Sponsored in part by:
Bureau of Radiological Health
Food and Drug Administration
U.S. Department of Health,
Education, and Welfare
With cooperation from:
^
American Association of
Physicists in Medicine
U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary
Luther H. Hodges, Jr., Under Secretary
Jordan J. Baruch, Assistant Secretary for Science and Technology
NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
Issued September 979
1
Library of Congress Catalog Card Number: 79-600133
National Bureau of Standards Special Publication 554
Nat. Bur. Stand. (U.S.), Spec. Publ. 554, 172 pages(Sept. 1979)
CODEN: XNBSAV
U.S. GOVERNMENT PRINTING OFFICE
WASHINGTON: 1979
ForsalebytheSuperintendentofDocuments, U.S. Government Printing Office, Washington, D.C. 20402
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PREFACE
These are the proceedings of the Conference The papers are printed in the proceedings as
on Neutrons from Electron Medical Accelerators they were received from the authors and in the
held April 9-10, 1979 at the National Bureau of order in which they were presented in the sessions.
Standards, Gaithersburg, Maryland. When medical For convenience we have preserved the conference
accelerators such as betatrons, microtrons and notation for the sessions. To speed the publica-
electron linear accelerators are operated at tion of the proceedings, all papers were submitted
energies above about 10 MeV, neutrons can be pro- by the authors in camera-ready form. We are greatly
duced by photonuclear interactions with machine indebted to the authors and all those who assisted
components such as collimators, beam flatteners, in the preparation of the manuscripts. Their
etc. The purpose of this conference was to efforts have made it possible to get the proceedings
acquaint members of the scientific, radiotherapy, in print much more rapidly than would otherwise be
regulatory, and accelerator manufacturing com- the case.
munities with the latest state-of-the-art
information concerning this neutron production. When commercial equipment, instruments and
materials are mentioned or identified in this
The program opened with a keynote address proceedings it is intended only to adequately
which was followed by five invited paper sessions. specify experimental procedure. In no case does
These sessions were concerned with the uses of such identification imply recommendation or
high energy beams in radiotherapy; the existing endorsement by the National Bureau of Standards,
regulations, their interpretation and application; nor does it imply that the material or equipment
the biological effects of neutrons and the identified is necessarily the best available for
appropriate quality factors to use in evaluating the purpose.
the hazard associated with a given electron
accelerator; the characteristics of neutron The Editors gratefully acknowledge the
radiation from existing accelerators, the instru- assistance of the National Bureau of Standards
mentation, measurement and calculational techniques Office of Technical Publications in the prepara-
available for determining the neutron spectral tion of these proceedings and of Mrs. Kathy Stang
fluence and dose in both the primary as well as of the National Measurement Laboratory and
the leakage beams; and finally what shielding and Miss Jo Ann Lorden of the Public Information
design techniques can be employed to reduce the Division for help in the arrangements for the
neutron production to a minimxam. The conference conference, and the excellent secretarial
closed with a summary session which was recorded assistance of Mrs. Karen Fritz and Mrs. Joan Donahue.
and is reproduced in full in these proceedings
for those interested in comments and review of
the full conference.
In order to achieve broad and even coverage
of the field, papers were presented by invita-
tion only although attendance at the conference
was open to anyone. In spite of the highly
specific topic of the conference there were 208
registrants with 22 participants from 8 foreign
countries.
H. Thompson Heaton, II
National Bureau of Standards
Robert Jacobs
Bureau of Radiological Health
iii
,
ABSTRACT
These proceedings are the compilation of 18 papers presented at the
Conference on Neutrons from Electron Medical Accelerators held in
Gaithersburg, MD on April 9 and 10, 1979. The topics addressed include:
properties of high energy beams for radiotherapy, regulations, biological
interpretation, physical measurements and calculations, and neutron
reduction techniques.
Key words: Dosimetry, high energy radiotherapy beams, leakage, measure-
ment techniques, medical accelerators, neutrons, relative biological effei
standards, shielding techniques.
iv
TABLE OF CONTENTS
Preface
,
Abstract
. .
Conference Personnel
KEYNOTE ADDRESS
Unwanted Neutron Contribution to
Megavoltage X-ray and Electron Therapy
J. S. Laughlin, A. Ried, L. Zeitz, and J. Ding
BEAMS FROM HIGH ENERGY ACCELERATORS FOR RADIOTHERAPY
Chairman: H. E. Johns
Advantages and Properties of High
Energy Photon Beams
H. E. Johns
Use of High Energy X rays in Cancer
Cure
W. E. Powers
Scattered Radiation Relative to Leakage
Radiation in High Energy X ray Beams
J. A. Rawlinson
REGULATIONS
Chairman: R. S. Caswell
International Standards for Medical
Accelerators
G. R. Higson •.
State Regulations for Medical Accelerators
C. H. Smith
BIOLOGICAL INTERPRETATION
Co-chairmen: J. A. Devanney
L. M. Bates
The RBE of Neutrons
H. H. Rossi
Risk of Cancer Based on Promotion
from Cytotoxicty
T. D. Jones, D. G. Jacobs, J. A. Auxier, and G. D, Kerr . . . ,
Clinical Tradeoff: The Maximum
Probability of Uncomplicated Cure
L. Cohen
Dependence of Radiation-Induced
Neoplastic Transformation In Vitro
Upon Radiation Quality and Repair
A. Han and M. M. Elkind
PHYSICAL MEASUREMENTS AND CALCULATIONS
Co-chairmen; G, R. Holeman
W, P. Swanson
Neutron Sources and Their
Characteristics
R. C. McCall and ............
W. P. Swanson 75
Mixed Photon-Neutron Field Measurements
R, Nath, K. W. Price and
G. R. Holeman 87
Neutron Contamination in the
Primary Beam
P. H. McGinley and
M. Sohrabi 99
Neutron Production from Electron
Accelerators Used for Medical Purposes
E. J. Axton and
A. G. Bardell
Survey of European Measurements on
Photoneutron Production from Electron
Accelerators Used for Medical Purposes
E. J. Axton and
A. G. Bardell
Neutron Leakage from Current Machines
P. R. Almond
NEUTRON REDUCTION TECHNIQUES
Chairman: C. S. Nunan
Design Criteria for Photon Beam Exits
on High Energy Medical Accelerators
Accelerators to Minimize Neutron Production
L. Taumann 139
Neutron Leakage Characteristics Related
to Room Shielding
E. Tochilin and
P. D. LaRiviere ^ 145
SUMMARY PANEL DISCUSSION 155
List of Attendees 163
Author Index 175
vi
CONFERENCE PERSONNEL
Conference Co-chairmen
J. E. Leiss
National Bureau of Standards
J. C. Villforth
Bureau of Radiological Health
Program Committee
L, M. Bates J, S. Laughlin
American Association of Physicists Memorial Sloan-Kettering Cancer
in Medicine Center
R. S, Caswell R. C. McCall
National Bureau of Standards Stanford Linear Accelerator Center
J. A. Devanney J. McDonald
Bureau of Radiological Health Memorial Sloan-Kettering Cancer
Center
E. G. Fuller
National Bureau of Standards C. S. Nunan
Varian
H. T. Heaton, II
National Bureau of Standards R. Schneider
Bureau of Radiological Health
G. R. Holeman
Yale University R. J. Schultz
Yale University
R. Jacobs
Bureau of Radiological Health W. P. Swanson
Stanford Linear Accelerator Center
vii