1、 ANSI N449.1-1978American National Standard Procedures for Periodic Inspection of Cobalt-60 and Cesium-137 Teletherapy EquipmentSecretariat for N44Institute of Electrical and Electronics Engineers, IncApproved April 7, 1977Reaffirmed August 7, 1984American National Standards InstitutePublished byIns
2、titute of Electrical and Electronics Engineers, Inc345 East 47th Street, New York, NY 10017 Copyright 1978 byThe Institute of Electrical and Electronics Engineers, IncNo part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without theprior written p
3、ermission of the publisher.American National StandardAn American National Standard implies a consensus of those substantially concerned with its scope and provisions.An American National Standard is intended as a guide to aid the manufacturer, the consumer, and the general public.The existence of an
4、 American National Standard does not in any respect preclude anyone, whether he has approved thestandard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures notconforming to the standard. American National Standards are subject to periodic review and users
5、are cautioned toobtain the latest editions.CAUTION NOTICE:This American National Standard may be revised or withdrawn at any time. The procedures ofthe American National Standards Institute require that action be taken to reaffirm, revise, or withdraw this standard nolater than five years from the d
6、ate of publication. Purchasers of American National Standards may receive currentinformation on all standards by calling or writing the American National Standards Institute.iiiForeword(This foreword is not a part of ANSI N449.1-1978, Procedures for Periodic Inspection of Cobalt-60 and Cesium-137 Te
7、letherapyEquipment.)This guidelines for inspection of teletherapy equipment are the product of Subcommittee N44.2, and its original draftof 1973 was written by Peter Vreeling. Priority for the attention of N44.2 on this subject of periodic inspection wassuggested by the Bureau of Radiological Health
8、 (BRH) of the United States Department of Health, Education andWelfare. For those several early years of N44.2 the BRH was the sponsor of the subcommittee and some of the mostproductive work on this standard (ANSI N449.1-1978) was done at meetings in BRH headquarters. Urgency forpromulgation of stan
9、dards for periodic inspection of teletherapy apparatus was stimulated by a fatality occurring whena patient was crushed by a cobalt teletherapy whose deficiency might have been corrected by appropriate maintenanceand inspection. It is a tribute to teletherapy apparatus, in general, that few serious
10、accidents have been reported withsuch machines which became the “conventional radiotherapy devices” of the 1950s, 1960s and even the 1970s.Complacency can follow decades of safe and dependable use of cobalt and cesium teletherapy machines, and thismaintenance guide is designed to avoid accidents and
11、 inaccuracies of output.When the BRH deemed it in conflict with their bureau to continue sponsorship of N44.2, the subcommittee onstandards for radiotherapy equipment IEEE took on the task of continued sponsorship of N44.2, and the task ofcompletion of this maintenance standard by obtaining final ap
12、proval by formal balloting.Members of N44.2 assisted Peter Vreeling in their numerous reviews and meetings, but the brunt of the work indeveloping N449.1 was borne by Peter Vreeling, himself. Consensus and suggestions of overlapping pertinentstandards from other national and international agencies w
13、ere supplied by members of the subcommittee.N44.2 aimed its efforts toward supplying useful information on periodic inspections of teletherapy apparatus to users(physicians and physicists), manufacturers, and regulators (for example, BRH). During the multiple meetings anddiscussions on safety for te
14、letherapy, the increase in numbers of linear accelerators was recognized, and theimportance of promulgating standards for these complex devices was noted. But the relatively simpler job ofestablishing standards for cobalt teletherapy machines was elected because of the need for such a standard, and
15、also toafford a prototype standard for subsequent promulgation of similarly needed guides for linear accelerators.At the time it approved this standard, American National Standards Committee on Equipment and Materials forMedical Radiation Applications had the following personnel:A. B Brill, MD, PhD,
16、 Chair John Tagler, Secretary American Association for the Advancement of Science N. Suntharalingam, PhDCharles L Dunham, MD (Alt)American Association of Obstetricians and Gynecologists. Clayton T. Beccham, MDGeorge C. Lewis, Jr, MD (Alt)American Association of Physicists in Medicine. Robert M. Quil
17、lin, MPHLeonard Stanton, MS (Alt)American Chiropractic Association Joseph W. Howe, DCT. M. Goodrich, DC (Alt)American Conference of Governmental Industrial Hygienists Gordon LoddeJacqueline Messite, MD (Alt)American College of Physicians Henry N. Wagner, Jr, MDJoseph F. Ross, MD (Alt)American Colleg
18、e of Radiology S. Reid Warren, Jr, ScDArgonne Cancer Research Hospital Katherine A. LathropPaul V. Harper, MD (Alt)American Chemical Society . Ellis P. Steinberg, PhDAmerican Dental Association . Albert G. RichardsLeonard M. Kraske, MD (Alt)American Federation of Labor and Congress of Industrial Org
19、anizations .George TaylorJack Suarz (Alt)Armed Forces Radiobiology Research Institute Lester A. Slaback, JrJohn M. Arras (Alt)American Insurance Association Leo G. FoxwellHarry W. Rapp, Jr (Alt)ivAtomic Industrial Forum, Inc .W. R. Konneker, PhDAmerican Medical Technologists John M. RhodesThomas A.
20、Pence (Alt)American Nuclear Society Herbert M. Parker, PhDAmerican Osteopathic Association. William E. Betts, Jr, PhDRobert R. Rosenbaum, MD (Alt)American Osteopathic College of Radiology . M. Carmen Pettapiece, MDRobert R. Rosenbaum, MD (Alt)American Pharmaceutical Association . William BrinerCharl
21、es H. Barnstein, MD (Alt)American Podiatry AssociationSidney B. Roth MDAmerican Public Health Association Rodney Dean Ice, PhDStanley J. Malsky, PhD (Alt)American Roentgen Ray Society. Charles A. Bickham, Jr, MDHomer L. Twigg, Jr, MD (Alt)American Radium Society . Morris J. Wizenberg, MDAmerican Soc
22、iety of Clinical Pathologists . Welby N. Tauxe, MDAmerican Society of Hospital Pharmacists.Barry M. BowenAmerican Society of Mechanical Engineers Allan B. DrosinAmerican Society for Quality ControlVacantAmerican Society of Radiologic Technologists. John H. Tolan, RTStephen Hiss, RT (Alt)Association
23、of State and Territorial Health Officers.Richard M. FryMartin C. Wukasch (Alt)American Veterinary Medical AssociationFrank A. Todd, MPH, DBMLeo A. Whitehair, DBM, MS, PhD (Alt)Brookhaven National Laboratory.H. Atkins, MDRalph Fairchild, PhD (Alt)Battelle-Northwest Memorial Institute (Nonvoting) Carl
24、os E. Newton, JrH. V. Larson (Alt)Bureau of Radiological Health Marshall S. LittlePeter Paras, PhD (Alt)College of American PathologistsJohn R. Hansell, MDWolfgang Hauser, MD (Alt)Department of Defense Office of the Surgeon.General David H. WoodRobert M. Quillin, MPH (Alt)Electronic Industries Assoc
25、iation.D. C. FleckensteinL. M. Rundlett (Alt)Food and Drug Administration . Earl L. Meyers, MDHealth Physics Society.John Hale, PhD (Alt)Institute of Electrical and Electronic EngineersCharles A. BurnhamThe Metallurgical Society of AIME .J. Lawrence Katz, PhDEvan Greener, MD (Alt)National Bureau of
26、Standards Robert Loevinger, PhDElmer H. Eisenhower (Alt)Wilfrid B. Mann, PhDNational Cancer Institute . Robert W. SwainNational Council on Radiation Protection and Measurements. Herbert M. Parker, PhDNational Electrical Manufacturers Association T. H. RogersJoel Hixson (Alt)National FormularyCharles
27、 H. Barnstein, MDElmer O. Krueger (Alt)National Naval Medical Center.VacantNuclear Regulatory Commission Allen Brodsky, PhDLeo Wade, PhDNaval Research Laboratory.Robert L. FlournoyRonald B. Luersen (Alt)Parenteral Drug Association Robert Varney, MDThomas H. Riggs (Alt)Puerto Rico Nuclear Center .E.
28、Theodore Agard, PhDA. E. Lanaro, MD (Alt)Radiological Society of North America Harold N. Schwinger, MDNorman Simon, MD (Alt)Scientific Apparatus Makers Association. Robert A. Arrison, JrJ. B. Rickey (Alt)Society of Nuclear Medicine . John U. Hidalgo, PhDSouthwest Research Institute Edward E. Dean, M
29、DH. Haskell Ziperman, MD (Alt)The United States Pharmacopeia Gordon E. Lindenblad, PhDE. James Potchen, MD (Alt)Veterans Administration. John R. BoggsChester B. Land (Alt)Gerald J. Hine, PhDvCLAUSE PAGE1. Scope.12. Objective .13. General Considerations .14. Test Procedures .24.1 General . 24.2 Sourc
30、e-condition Indicator. 34.3 Door Interlock 34.4 Source Holder/Shutter Movement . 34.5 Protective Source Housing, Beam-Off Leakage 34.6 Head Movement. 54.7 Beam Orientation . 54.8 Source Leakage 54.9 Central-Axis Indicator 54.10 Light-Radiation-Field Congruence 54.11 Isocenter Position. 74.12 Source-
31、Skin Distance (SSD) 104.13 Source Output 114.14 Timer 114.15 Stand and Stretcher 134.16 Manual Source/Shutter Return. 144.17 Pneumatic System 144.18 Overhaul of Electrical, Mechanical, and Source Assemblies 145. Radiation Safety146. Records147. References.15Copyright 1978 IEEE All Rights Reserved1Am
32、erican National Standard Procedures for Periodic Inspection of Cobalt-60 and Cesium-137 Teletherapy Equipment1. ScopeThis guideline provides suggested procedures for the inspection of cobalt-60 and cesium-137 teletherapy equipmentwhich may identify and quantify malfunctions or maladjustments of the
33、safety and radiation defining components.This guideline is a companion document to ANSI N449-1974 1, which specifies tests and suggested frequencies forthe inspection and maintenance of teletherapy equipment.2. ObjectiveThe objective of the standard is to provide users of the teletherapy units with
34、suggested procedures for performing theperiodic inspection of their equipment as specified in ANSI N449-1974 1. Methods and equipment are listed for eachprocedure.3. General ConsiderationsThe procedures included in this document are not intended to be all-inclusive. Other procedures may be equallysa
35、tisfactory. However, the procedures described here have been used successfully and will give results with sufficientaccuracy to meet the recommended tolerances when performed by competent people with appropriate equipment.Appropriate equipment means equipment which is functioning properly and of rel
36、evant accuracy and reproducibility.Persons performing the test shall be competent in use of the test equipment, the teletherapy unit, and the proceduresperformed. A “qualified expert” as defined by the NCRP is acceptable in this regard.NOTE Qualified Expert: With reference to radiation protection, a
37、 person having the knowledge and training to measure ionizingradiation, to evaluate radiation safety techniques, and to advise regarding protection needs. With reference to thecalibration of radiation therapy equipment, a person having, in addition to the above qualifications, training andexperience
38、 of the clinical applications of radiation physics to radiation therapy 2.2Copyright 1978 IEEE All Rights ReservedANSI N449.1-1978 PROCEDURES FOR PERIODIC INSPECTION OF COBALT-60Persons performing service and maintenance of the teletherapy unit shall be trained and experienced in radiation safetyand
39、 operation of the teletherapy unit and its components, and properly equipped with replacement parts, handlingequipment, and other special equipment dictated by the individual service procedure. Upon completion of anyserviceoperation no matter how minor and before commencing use of the teletherapy un
40、it or accessories, the unit andancillary equipment shall be tested to assure mechanical, electrical, and radiation safety of the equipment.NOTE These tests should not be construed as taking the place of constant vigilance in observation of the patient and equipmentby therapy personnel during use of
41、the equipment since electrical and mechanical failures may occur despite frequenttesting of machines and associated equipment.4. Test Procedures4.1 GeneralTable 1 gives the tests and a suggested sequence of tests to check the teletherapy unit for compliance with therecommended objective and specific
42、ation. Performance of the tests in the suggested sequence should minimize theneed for repetitive testing and duplication of effort and provide redundant checks on radiation beam and mechanicalparameters.Table 1Tests in their Recommended SequenceTests Objective SpecificationsSource-condition indicato
43、r (see Sec 4.2) source position or condition onoffDoor interlock (see Sec 4.3) fail-safe operation yesnoSource holder/shutter movement (see Sec 4.4) smooth and rapid movement reproducible, mfr specsSource housing leakage (see Sec 4.5) safe leakage radiation levelless than 2 mR/h average and 10 mR/h
44、maximum at 1 mHead movement (see Sec 4.6)smooth, stable, indicator accurateindicator 1Beam orientation (see Sec 4.7) limit switches working yesnoSource leakage (see Sec 4.8) no removable contamination less than 50 nCi*NOTE: Since publication of ANSI N449-1974, certain state regulatory agencies have
45、lowered the allowable limit for removable contaminationfrom 50 nCi to 5 nCi. The US Nuclear Regulatory Commissions limit remains at 50 nCi.Central-axis indicator (see Sec 4.9) centrally located2 mmLight-radiation-field (see Sec 4.10) congruence3 mm on any side for a 10 10 field at depth of dose maxi
46、mumIsocenter position (see Sec 4.11) stable isocenterwithin a sphere not greater than 4 mm in diameterSSD indicator (see Sec 4.12) accurate and reproducible3 mmSource output (see Sec 4.13) calibration and output accurate/reproducible within 3 percentTimer (see Sec 4.14) accurate and reproducible rep
47、roducibleStand-stretcher (see Sec 4.15) stable and accurate indicators Manual source/shutter return (see Sec 4.16) equipment available and usable Pneumatic system (see Sec 4.17) functioning properly free of water and pressurizedCopyright 1978 IEEE All Rights Reserved3AND CESIUM-137 TELETHERAPY EQUIP
48、MENT ANSI N449.1-1978As a matter of general good practice, a minimum of three instrument readings should be taken at each data point. Forexample, three readings of source transit time to “on” and three readings to “off” should be made. All readings arerecorded and the average used as the data point.
49、 When using an ionization chamber for radiation measurements, theirradiation time and instrument scale should be chosen so as to utilize the most accurate and reproducible part of thescale. For instance, if a condenser R-chamber was calibrated at 50 percent of full scale and is shown to be linearbetween 20 and 80 percent of full scale, irradiation times should be utilized which will result in readings between 20and 80 percent of full scale.Maintenance operations for individual teletherapy units which are ordinarily performed by manufacturer or distributors
