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Gamma camera

Introduction

The objective of a quality control programme of the gamma camera is to assure that the findings in the patient examination have their origin in the patient and not in the gamma camera itself. In such a complex system as a modern gamma camera there are many factors that contribute to the final image quality and if not kept under control they will result in a misinterpretation of the examination in terms of false positive or false negative results. A thorough evaluation of the gamma camera system at installation, and a comprehensive routine quality control programme, will guarantee reliable function and detect the majority of problems that can occur. Another important factor in a quality control programme is the nuclear medicine specialists and the technologists ability to recognize the types of artifacts that will occur in the images due to improper function of the equipment. A system of communication and reporting is fundamental, and the medical physicist has a key position in this.

Important principles

A quality control programme for new equipment should start with an acceptance test to verify the equipment meets the specifications given by the vendor. The acceptance test should be performed according to accepted international standards and may require the use of instruments and phantoms not available in the department. The acceptance test forms the basis of the reference tests routinely performed in the department during the life-time of the equipment according to a schedule worked out by the medical physicist in cooperation with the nuclear medicine department. Certain parameters should be tested daily, others on weekly, monthly and yearly basis. Recommendations given by international, national and professional organizations should be followed. Reference testing is particularly important in order to detect and correct long-term slow deterioration in quality.  Furthermore the complexity of the equipment and the nature of the routine clinical investigations demand effective day-to-day control to ensure the validity of results.

Introduction to references

There is extensive literature on gamma camera quality control, including articles in scientific journals, textbooks and documents as well recommendations from different organizations (NEMA, IEC) and professional bodies (IPEM, ACR, EANM). The IAEA has published two detailed documents covering QA and QC procedures for scintillation camera systems as well as an assortment of examples of possible image errors and problems  The publications were written with the objective to provide professionals in nuclear medicine centers with detailed quality control test procedures for the scintillation camera and computer system. Some information on QC of gamma cameras can also be found on the IAEA web-site Radiation Protection of the Patient as well as in the review article by Zanzonico.