Well Scintillation Counting Systems for Nuclear Medicine Applications Indeveloping Countries

IAEA-201 WELL SCINTILLATION COUNTING SYSTEMS FOR NUCLEAR MEDICINE APPLICATIONS INDEVELOPING COUNTRIES REPORT OF A CONSULTANTS' MEETING ORGANIZED BY THE INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 23-25 MAY 1977 t#\ ~ A TECHNICAL DOCUMENT ISSUED BY THE (4..)INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, 1977 Printed by the IAEA in Austria September 1977 PLEASE BE AWARE THAT ALL OF THE MISSING PAGES IN THIS DOCUMENT WERE ORIGINALLY BLANK The IAEA does not maintain stocks of reports in this series. However, microfiche copies of these reports can be obtained from INIS Microfiche Clearinghouse International Atomic Energy Agency Kimtner Ring 11 P.O. Box 590 A-1011 Vienna, Austria on prepayment of US $0.65 or against one IAEAmicrofiche service coupon. FOREWORD Nuclear medicine instruments employed in developing countries are usually acquired from the commercial market in developed countries. They thus embody the technological refinements characteristic of that market, but are by the same token optimized for purposes and conditions of use that may differ substantially from those found in developing countries. Furthermore, the diversity of instruments in this market is great, and their design is undergoing a very rapid evolution. It is, therefore, inevitable both that the instruments are not optimized for use in developing countries and that a rational selection even from among those available is difficult for the consumer in the developing country to make. A consultants' meeting was organized by the Medical Applications Section of the Division of Life Sciences, IAE&, during the period 23-25 May 1977, to examine well scintillation counting systems in the light of the requirements of laboratories in developing` countries. The deliberations of these consultants, summarized in this report, may provide guidance both as to selection from currently available instruments and as to directions in instrument design that might be followed to the advantage of such laboratories. CONTENTS I. Introduction ....................................... 1 II. General Remarks ..................................... 2 III. Tasks for Well Scintillation Counting Systems ......... 4 IV. Manual vs. Automatic Counting Systems ................. 6 V. Desirable Characteristics of Manual Well Scintillation Counters ................. ........... 6 VI. Automatic Well Scintillation Counters ................. 9 VII. Alternative Systems for Handling Samples Containing 2 I .............................. 15 VIII. Conclusions and Recommendations ....................... 15 Appendix 1. Participants in Consultants t Meeting ............ 19 Appendix 2. Characteristics of Commercially Available Well Scintillation Counting Systems .......... 20 Appendix 3. Agency's Prototype Automatic Well Scintillation Counter . .... ...... 37 WELL SCINTILLATION COUNTING SYSTEMS FOR NUCLEAR MEDICINE APPLICATIONS IN DEVELOPING COUNTRIES I. INTRODUCTION *) This Group of Consultants) was convened by the Medical Applications Section of the International Atomic Energy Agency to identify the design characteristics that well scintillation counting systems should incorporate in order to perform nuclear medicine measurements effectively in developing countries. The term "well scintillation counting system" was taken to include any system optimized to measure the activity of gamma-ray emitting samples of volume up to about 5 ml, whatever the size and form of the cavity in which the sample was located while being measured. Systems intended for measurement of bulk samples, such as urine and faeces, were not considered. (However, it was noted that a detector designed for the former purpose could function well in the latter application with suitable adaptations (Potter, 1977).) The context of the meeting was summarized in introductory remarks by the Agency's Secretariat. The Medical Applications Section has as one component of its programme an effort to assure a more effective use of nuclear medicine instruments in developing countries. This effort has three facets: (1) identification of the most rewarding applications of nuclear medicine techniques, (2) identification of favourable design attributes of instruments used in such applications, and (3) development of maintenance strategies to assure reliable performance of the instruments once put into service. It must be expected that with regard to all three facets the circumstances distinctive to developing countries - in health, in wealth, in technological capability - would lead to allocations of priorities and resources somewhat different from those in the developed countries *) Members of the Group are listed in Appendix 1. - 1 - where most applications and instruments have originated. This meeting of consultants, convened in relation to the second facet, was the first of a series planned by the Medical Applications Section to examine in turn the design attributes of specific instrument systems. It was hoped that the recommendations of the Group would help the Agency and laboratories in its Member States to select from among the multitude of available instruments the most suitable well scintillation counting systems for their purposes, and also that they would guide the Agency in its attempts to stimulate the development of more appropriate instruments of this type. The Group took particular note of the reports of two previous meetings organized by the IAEA and WHO. The first of these (WHO, 1976), in analyzing how nuclear medicine services could be best established at various levels of medical care, described some of the conditions nuclear medicine instruments should meet in developing countries. The second (IAEA, 1976), in reviewing the problem of maintenance of nuclear medicine instruments in developing countries, identified certain design attributes that might alleviate maintenance difficulties. The Group also made reference to a collection of brochures provided by the Secretariat on currently available commercial well scintillation counting systems (summarized in Appendix 2), and to a recent review of automatic counters for gamma-ray emitting samples (Robert S. First, Inc., 1977). The following report gives the opinions and r commendations of the Group on the issues it was asked to review. II. GEIMRAL REWMRES In terms of the numbers of patients studied or the numbers of tests performed, it is likely that well scintillation counters are the single most important instrument system in nuclear medicine laboratories in developing countries. As is evident from Appendix 2, the equipment currently available ranges from manual instruments priced at a few hundred dollars to large systems costing nearly one hundred times as much and offering automated sample changing and -2- data processing. In view of this wide range of options, it is worthwhile to examine which of the features may be of greatest importance in developing countries. In general terms, and drawing upon the two IAEA and WHO documents already referred to, high priority should be given to the following features : (1) Low cost. This is doubly important, first because funds are anyway limited, second because it is highly desirable at present levels of instrument reliability to duplicate instrumentation, both to insure that at least one working instrument will be available at all times and to assist diagnosis of faults by substitution of component parts. (2) Ease of operation. Equipment may be operated by personnel with less specialized training than is the case in developed countries, and requirements for complicated adjustments of instruments may not be reliably observed. (3) Convenience of quality control. It should be possible to discover the existence of faults by use of simple tests not requiring technical knowledge. (4) Freedom from breakdown and ease of repair if it occurs. Spare parts and trained servicemen are often unavailable, and major administrative barriers involving customs and currency exchange regulations impede acquisition of support from outside the country. (5) Capability to operate satisfactorily in the presence of unreliable electrical mains. Mains voltage levels in many laboratories undergo wide fluctuations, and power failures are common. As discussed in the remainder of this report, it appears that these objectives are most likely to be reached with the following approach. A laboratory should start with a basic manual well scintillation counter capable of giving reasonable performance for most tasks. This instrument should have certain further attributes: (1) It should be constructed of components, preferably on plug-in boards, for which spares and service are locally available. (2) It should form part of an instrument system that upgrades and degrades gracefully, i.e., it should be possible to improve performance by addition of options (e.g., a sample changer) without expensive -3- conversion or replication of existing features, and if part of the upgraded instrument were to break down the surviving components should be capable of still performing satisfactorily, even if at a lower level of sophistication (e.g., failure of a printer or sample changer should not prevent manual use). (3) The system should have diagnostic indicators or test routines capable of revealing the location of faults. (4) The system should be capable of operating from a battery power supply. At present there are few if any commercial instruments that offer all of these features, and there are several barriers that make difficult their realization. To some extent the goals are themselves contradictory. In

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