RADIATION PROTECTION CRITERIA AND STANDARDS: THEIR BASIS AND USE FRIDAY, JUNE 3, 1960 CONGRESS OF THE UNITED STATES, SPECIAL SUBCOMMITTEE ON RADIATION, Washington, D.C. The subcommittee met, pursuant to recess, at 10:05 a.m., in room P-63, the Capitol, Hon. Chet Holifield (chairman of the subcommittee) presiding. Present: Representative Holifield, Senators Hickenlooper and Aiken, and Representative Hosmer. Also present: James T. Ramey, executive director; and Carey Brewer, professional staff member; Hal Hollister and James E. Turner, technical consultants. Representative HOLIFIELD. The committee will be in order. The subcommittee will continue its hearings on Radiation Protection Criteria and Standards, Their Basis and Use." Our first witness this morning will be Dr. Seymour Yale, University of Illinois, and Dr. George Paffenbarger, Washington, D.C., representing the American Dental Association. Gentlemen, will you please come forward? STATEMENT OF DR. SEYMOUR YALE, UNIVERSITY OF ILLINOIS; ACCOMPANIED BY DR. GEORGE PAFFENBARGER,2 WASHINGTON, D.C., REPRESENTING THE AMERICAN DENTAL ASSOCIATION Dr. PAFFENBARGER. Mr. Chairman, I am George C. Paffenbarger, director of the American Dental Association's research division at the National Bureau of Standards. With me is Dr. Seymour H. Hale of Chicago, Ill. Before I introduce Dr. Yale, I should like to outline for this committee some of the activities of the American Dental Association in the field of radiation protection over the years. The association is fully aware of its great responsibility for the proper use of the X-ray 1 Born Nov. 27, 1920, at Chicago, Ill. Married with two children. B.S. 1944, University of Illinois; D.D.S. 1945, University of Illinois, College of Dentistry: Graduate School, University of Illinois, 1947-48. 1945, engaged in private dental practice; 1948, associated with the College of Dentistry, University of Illinois; since 1957, professor and head of the department of radiology. Member of the advisory editorial board of the International Association for Dental Research (J. dental research) and member of the American Standards Association Sectional Committee (dental film specifications). Born in McArthur, Ohio, on Nov. 3, 1902. Graduated from the College of Dentristy, Ohio State University in 1924 with honors. Palama Settlement Dental Clinic, Honolulu, 1925-26; instructor in the College of Dentistry, Ohio State University, 1927-28; and research associate of the American Dental Association at the National Bureau of Standards, 1929-41, and since 1946. 1942-46 served in the Dental Corps of the U.S. Navy at the Naval Medical Supply Depot, Brooklyn, N.Y.; advanced from lieutenant commander to commodore; now holds the rank of rear admiral in the U.S. Navy Reserve. machines in the offices of members of the dental profession. At the present time it is reliably estimated that the 83,000 dentists engaged in private practice own and operate approximately 95,000 dental X-ray machines. Through the several media available to it, the association exerts strong influence in educating dentists and the public in this field as one of many which concern the practice of dentistry and the health of the Nation. The Journal of the American Dental Association carries scores of timely articles on the proper use of diagnostic radiation, and new information is brought to the profession in this way as soon as it becomes available. The association has prepared and distributed several educational movies on radiographic technique in the dental office, which demonstrate hygienic measures for the protection of the patient and the professional and technical staff. This association has produced these in cooperation with the National Bureau of Standards. The first of these motion pictures was produced in 1953 and, by the way, won the second prize at the Vienna International Film Festival in the medical category. Another one was prepared and is now in distribution, and it is entitled "Dental X-ray Equipment, Its Alteration for Modern Radiation Hygiene." At the present time the American Dental Association, in cooperation with the American Standards Association, is preparing a specification for a dental X-ray film. The association has had several symposia and has tried to establish at all the local levels programs on radiation hygiene for the benefit of the local practitioners. Essays and clinical presentations in the field of radiography are encouraged and invited for the programs of the various meetings of dental organizations at the national and community levels. The association has kept its membership informed concerning State legislation requiring registration and inspection of radiation producing devices. One of the principal objectives of these communications has been to encourage dentists to cooperate in the administration of State radiation protection laws. Recently, in cooperation with the American College of Radiology, the American Dental Association produced a booklet on radiation protection and hygiene and distributed it to every dentists in the United States. By the way, the Indiana Dental Association has asked permission to reprint this booklet for the Indiana dentists in Asia. The American Dental Association, through its various agencies, also maintains excellent relations with the dental trade organizations, who make these dental apparatus for use in generating radiation. In this close cooperation, agreement is reached on the safety factors necessary in the production of machines. In cooperation with the National Bureau of Standards, the American Standards Association and other groups, the association is working on the development of standards and specifications for dental radiographic film, adoption of which eventually will contribute importantly to the stabilization of the X-ray dosage picture. The Association's Council on Dental Research continues to provide information on radiation hygiene to dentists and dental auxiliary personnel, and to cooperate with other agencies in fulfilling its obligations in this area. A consultant of the Council serves with the National Committee on Radiation Protection which is completing its re vision of Handbook 60. There is in this book a section on proper practices for maintaining radiation hygiene in the dental office. This Handbook No. 60, the principal one, is now being revised, and when the revision is finished, the Council plans to issue a report to the entire membership of the association. The association's interest in radiation and radiation protection will continue as long as dentists use radiographic means for the detection of oral diseases, as they realize the extreme importance of it. It is a privilege to cooperate with this committee in providing information on the association's participation in the movement to reduce unnecessary exposure to radiation from all sources, and in the interest of the public welfare. To give further insight into the technical aspects of the matter from the dental standpoint, I would like to introduce Dr. Seymour H. Yale of Chicago, Ill., who will present the remainder of our statement. Dr. Yale is a professor and head of the Department of Radiology, College of Dentistry, University of Illinois and is a consultant on radiology to the Council on Dental Research of the American Dental Association. He has published many articles on radiology and is eminently qualified to speak on the subject, and he has had the active cooperation of the Argonne National Laboratories in this particular work at the University of Chicago. Now I would like to introduce Dr. Yale, Mr. Chairman. Dr. YALE. Mr. Chairman, members of the committee, the dentist has four objectives in employing the radiographic examination as a diagnostic aid in rendering a complete oral health service: 1. To recognize frank disease processes: bony tumors, bony cysts, changes in the jawbones occurring in certain systemic diseases, bony periodontal pockets, dental caries, etc. 2. To discover evidence of these and other oral diseases in their incipiency, or early stages. 3. To serialize or record the chronological progress of the growth and development of oral tissues and the treatment of oral disease involving bone and tooth structures. 4. To apprise the patient of his existing good oral health when radiographic examination reveals the absence of oral disease, either of a local or a systemic nature. Cognizant of its total responsibilities in the utilization of X-radiation in oral diagnosis, dentistry has established a two-front attack focused upon the reduction of radiation hazards. These areas are (1) intensive research, and (2) continuous professional education. The scope of research activity in radiation protection problems in dentistry is demonstrated in a review of the dental literature for 1958. During that year, 65 papers in the field of radiation protection appeared in English language dental journals. (Yale, S. H.: "Studies in Radiology," J.A.D.A. 58:36, May 1959.) The American Academy of Oral Roentgenology published a comprehensive report on recommendations for X-ray protection in the dental office which included appendixes listing suppliers of film badge services, ionization chamber dosimeters, replacement timers, and barrier materials. (Richards, A. G., and others: "X-Ray Protection in the Dental Office." J.A.D.A. 56-514, April 1958.) Under the cosponsorship of the American College of Radiology and the American Dental Association, additional practical information on the control of radiation hazards was supplied in a manual listing a number of methods for insuring good radiation hygiene in the dental office, including proper collimation and filtration, use of fast films, and emphasis on special care with children and pregnant women. (Chamberlain, R. H., and Nelsen, R. J.: "A Practical Manual on the Medical and Dental Use of X-Rays With Control of Radiation Hazards." Sponsored by the American Dental Association, Chicago. American College of Radiology, 1958.) Gonadal exposure of patients: The genetic effects of the X-radiation used by dentists have been widely discussed. The dental contribution to the 10-roentgen 30-year gonadal dose is estimated by radiobiologists at approximately 1 roentgen. Independent findings of a number of dental researchers indicate that the 1-roentgen gonadal dose represents in excess of 200 full-mouth X-ray examinations of 14-20 films each per patient during this 30-year period. (Eselman, J. C.: "Radiation Intimidation-True or False." Penn. D. J. 25: 18, January 1958. Richards, A. G.: "Roentgen-Ray Doses in Dental Radiography." J.A.D.A. 56: 351-368, March 1958.) It should be noted that (1) this data is based upon the roentgen output of uncollimated, unfiltered X-ray machines, and (2) the average dental patient has less than 12-15 full-mouth X-ray examinations made during his first 30 years of life. It is clear that the actual exposure from dental diagnostic radiation is far below the margin recommended by the authorities. Survey of X-ray facilities and procedures in private dental offices: During 1958, it became apparent that a critical need existed for a statistical exaluation of the status of radiation hygiene practiced in dental offices in the United States. Based upon experience gained in an earlier pilot radiation survey, the Department of Radiology at the College of Dentistry, University of Illinois, was awarded a U.S. Public Health Service grant to assist in coordinating a large scale radiation survey program. The specific aim of the program was to conduct a survey of the X-ray facilities in 2,000 dental offices under actual operating conditions. Participating grants were awarded to each of 10 dental schools in the United States. In order to implement a significant geographic analysis of the data collected, the folowing dental schools were chosen: Baylor University, Dallas, Tex.; Detroit University, Detroit, Mich.; Emory University, Atlanta, Ga.; Indiana University, Indianapolis, Ind.; Temple University, Philadelphia, Pa.; Tufts University, Boston, Mass.; University of Kansas City, Kansas City, Mo.; University of Minnesota, Minneapolis, Minn.; University of Southern California, Los Angeles; and University of Washington, Seattle, Wash. Each of the 10 schools was charged with the collection of specific radiation data on 200 local dental offices. Preliminary findings of this program will be discussed later in this testimony. Survey of courses in radiation hygiene: A questionnaire requesting information on the number of undergraduate lecture hours devoted to radiation hazards and/or hygiene was recently sent to 45 dental schools in the United States. A 77.7 percent response indicates that an average of 4 hours of such lectures are being presented. In addition to formal lectures, some schools require extensive assigned reading in the area, and all schools stated that radiation hygiene was stressed in undergraduate clinical practice. Recommendations for reducing radiation exposure: Authorities are in agreement that four basic factors are operative in the reduction of radiation used by the dentist: (1) collimation of the X-ray beam, (2) selective filtration of the X-ray beam, (3) utilization of more sensitive X-ray film, and (4) employment of higher kilovoltage X-ray machines The reduction of beam size through collimation is accomplished by installing a lead washer in the port or opening of the dental X-ray machine. Although the size of the opening in the lead washer varies with each brand of machine, such variation in size provides a standard area of exposure, irrespective of the brand of X-ray machine used. Aluminum is most commonly used for filtration, or removal of the soft X-rays that do not contribute to the production of a good diagnostic X-ray film. (Lee, E. A.: Some Radiation Hazards of Dental X-Ray and Their Elimination. Bul. Monmouth Co. D. Soc. 11: (no paging) March 1958. Peters, H. A.: Specific Protective Measures for Dental X-Rays. Chron. Omaha Dist. D. Soc. 22: 80, November 1958.) A given dental X-ray machine may be filtered through the simple expedient of placing aluminum disks of predetermined thicknesses behind the collimator. Another method of filtration combines copper and aluminum disks. (Yale, S. H. and Goodman, L. S.: Reduction of Radiation Output of the Standard Dental X-Ray Machine Utilizing Copper for External Filtration. J.A.D.A. 54: 354, March 1957.) The rationale for and method of collimation and filtration have been cited repeatedly by research workers in dental radiology during the past 4 years. The experiences and findings of some of these researchers indicate that the dental procession in this country has developed an acute awareness of the need to maintain good radiation hygiene in practice. This concept is graphically demonstrated by the following studies: During the period extending from November of 1957 to March of 1958, a radiation survey was made of 122 X-ray machines in 113 dental offices in the Chicago area (Yale, S. H. and Hauptfuehrer, J. D.: Survey and Analysis of Roentgen Exposure to Dentists: Preliminary Report. J.A.D.A. 58:49-54, April 1959). Results of this survey showed that 22.6 percent of these machines were collimated and 16.8 percent were filtered. In a current comparable radiation survey of 2,000 dental offices in 10 States described earlier in this report, initial assessment of the data provided by 1,649 X-ray machines in 8 of these States indicates that now 69 percent of these machines are collimated and 56.3 percent are filtered. A second Chicago survey recently completed shows collimation and filtration data that compare favorably with the new national average. In the evaluation of such data, one may conclude that the widespread research and educational programs in radiation hygiene in dentistry are increasingly effective. Dental X-ray film is fundamentally similar to ordinary photographic film, in that increased sensitivity of the emulsion requires less energy for exposure. More sensitive photographic film requires less light, and more sensitive X-ray film requires less X-radiation to produce acceptable results. Data supplied by one of the leading manufacturers of dental X-ray film in the United States indicates that approximately 50 percent of such film currently produced by this manufacturer is of the more sensitive high-speed or fast type. In addition, this firm reports an 8 percent yearly increase in the rate of |