Quality control of nuclear cardiology procedures is a multiple-step process that begins before the patient enters the laboratory, continues during the acquisition and after the patient leaves the laboratory. It requires attention from the technologist as well as the physician. Requirements for imaging system quality control are based on Nuclear Regulatory Commission (NRC) and agreement state requirements, accepted imaging guidelines and standards and more recently the Intersocietal Commission for Accreditation of Nuclear Laboratory (ICANL) and American College of Radiology (ACR) Accreditation standards.1–6 The requirements and frequency may vary slightly between standards. However, the basic premise of why it is necessary is the same in all situations: to ensure adequate camera performance, identify any potential sources of error or artifact within an acquisition, and ultimately provide the patient and referring physician with the best quality information possible. If quality control procedures are not followed, it may lead to an equivocal or falsely interpreted study, which may result in increased downstream costs as well as poor outcomes. This chapter will review quality control procedures before, during, and after the acquisition of a nuclear cardiology study.
QUALITY CONTROL BEFORE THE ACQUISITION
There are several required and recommended equipment quality control procedures that should be performed on each imaging system.2,5–13 The recommended frequency of the procedures may vary among equipment manufacturers; however, all are important to ensure proper system performance (Table 4-1). These tasks consist of daily, weekly, and quarterly system testing.
Table 4-1Recommended Frequency for Gamma Camera Quality Control Procedures |Favorite Table|Download (.pdf) Table 4-1 Recommended Frequency for Gamma Camera Quality Control Procedures
|Test ||Frequency |
|Energy peaking ||Daily |
|Uniformity ||Daily |
|Sensitivity ||Daily or weekly |
|Resolution and linearity ||Weekly |
|Center of rotation ||Weekly |
|SPECT phantom evaluation ||Quarterly |
Energy peaking (photopeak analysis) should be performed daily to verify that the camera is counting photons using the correct energy.2,3,7–9 Each imaging system should be checked before use to ensure that the camera peaking electronics are functioning properly, that the energy window has not drifted, and that the energy spectrum is the appropriate shape.
During the procedure, the pulse height analyzer's energy window should be manually or automatically placed over the correct photopeak energy. It is recommended that no greater than a 2% energy window be used in order to obtain the most accurate peak energy.2,7–9 If the test is performed intrinsically, a point source should be placed at least 1.5 m away from the surface of the camera detector. If performed extrinsically, a sheet source should be used. In either case, the source should be enough to flood the entire field of view (FOV).
Verifying the photopeak ...