U. S. Department of Commerce Charles Sawyer, Secretary National Bureau of Standards A. V. Astin, Acting Director The Advisory Committee on X-ray and Radium Protection was formed in 1929 upon the recommendation of the International Commission on Radiological Protection, under the sponsorship of the National Bureau of Standards and with the cooperation of the leading radiological organizations. The small committee functioned effectively until the advent of atomic energy, which introduced a large number of new and serious problems in the field of radiation protection. At a meeting of this committee in December 1946, the representatives of the various participating organizations agreed that the problems in radiation protection had become so manifold that the committee should enlarge its scope and membership and should appropriately change its title to be more inclusive. Accordingly, at that time the name of the committee was changed to the National Committee on Radiation Protection. At the same time, the number of participating organizations was increased and the total membership considerably enlarged. In order to distribute the work load, eight working subcommittees were established, as listed below. Each of these subcommittees is charged with the responsibility of preparing protection recommendations in its particular field. The reports of the subcommittees are approved by the main committee before publication. The following parent organizations and individuals comprise the main committee: American Medical Association: H. B. Williams. American Radium Society: E. Quimby and J. E. Wirth. American Roentgen Ray Society: R. R. Newell and J. L. Weatherwax. National Bureau of Standards: L. S. Taylor, Chairman. National Electrical Manufacturers Association: E. Dale Trout. Radiological Society of North America: G. Failla and R. S. Stone. U. S. Air Force: W. S. Cowart, Lt. Col. U. S. Army: D. A. York, Lt. Col. U. S. Atomic Energy Commission: K. Z. Morgan and Shields Warren. U. S. Navy: W. H. Sullivan. U. S. Public Health Service: H. L. Andrews and E. G. Williams. Physics. Pur 7-31-The following are the subcommittees and their chairmen: Subcommittee 1. Subcommittee 5. Subcommittee 6. Subcommittee 7. Permissible Dose from External Sources, G. Failla. X-rays up to Two Million Volts, H. O. Wyckoff. Electrons, Gamma Rays and X-rays above Two Handling of Radioactive Isotopes and Fission Monitoring Methods and Instruments, H. L. Subcommittee 8. Waste Disposal and Decontamination, J. H. With the increasing use of radioactive isotopes by industry, the medical profession, and research laboratories, it is essential that certain minimal precautions be taken to protect the users and the public. The recommendations contained in this Handbook represent what is believed to be the best available opinions on the subject as of this date. As our experience with radioisotopes broadens, we will undoubtedly be able to improve and strengthen the recommendations for their safe handling, utilization, and disposal of wastes. This report does not endeavor to provide a complete. manual on radiological instruments. It is designed, however, to indicate the types of measurements and instruments that are necessary for determining the adequacy of radiation shielding. This applies to low-voltage and highvoltage X-ray installations, radioactivity laboratories, radium handling areas, etc. The Committee on Nuclear Sciences of the National Research Council is preparing detailed reports on specific instrumentation problems and the reader is referred to these reports for more detailed information. The present Handbook has been prepared by the Subcommittee on Monitoring Methods and Instruments. Its membership is as follows: H. L. ANDREWS, Chairman. C. B. BRAESTRUP. J. HEALEY. R. E. LAPP. W. H. RAY. J. E. ROSE. E. G. WILLIAMS. A. V. ASTIN, Acting Director. Contents Page 3. General principles of hazard control. 8. Beta- and gamma-radiation detectors_ 11. X- and gamma-radiation measuring instruments_ 12. Beta-radiation instruments.. 13. Alpha-particle instruments.. IV. Personnel monitoring instruments- Radiological Monitoring Methods and Instruments I. General 1. Scope of Report It is imperative that users of radioactive materials and other sources of radiation take adequate measures to prevent overexposure of personnel. Any adequate radiation protection program may require a variety of types of measuring instruments, and trained personnel must be available to insure the use of suitable instruments in the proper way, to interpret the readings obtained, and to make necessary recommendations for reducing hazards. The present report represents an attempt to establish some basic guides for methods of determining radiation hazards and selecting suitable instruments for measuring them. No attempt will be made to give detailed discussions of the recommendations. Radiation hazards arise from a wide variety of sources and the monitoring methods must vary accordingly. Sources such as X-ray units are relatively fixed in position and constitute radiation hazards only when they are in operation. Radioactive isotopes, on the other hand, are hazardous until natural decay has reduced the activity to safe levels. Furthermore, such materials may be spilled or lost during their use and become rather widely spread throughout a building or area. High-voltage accelerators represent an intermediate case, where the greatest hazard is present during operation, but where induced radioactivity may persist for some time after the equipment is shut down. The attainable characteristics of radiation-protection instruments are dependent on technical advances in electronics and in other fields. For this reason, specific recommendations may become obsolete as new designs are introduced. The present report considers only types that have proved useful in practice. Throughout this report a sharp distinction has been made between scanning and measuring radiation. Scanning is used to denote a rapid, qualitative survey, usually carried out with sensitive detecting instruments, to locate and determine the extent of a radiation source. Measuring refers to |