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Physical phantoms have been used to test the diagnostic proficiency of nuclear medicine professionals and the accuracy of their equipment in external quality assurance surveys. No dynamic renal phantoms are commercially available. A new renal phantom, presented in this paper, was constructed and patented in the United States. Methods: The organs to be simulated by the phantom were in the form of containers filled with radioactive solution, and the device further comprised movable steel and lead plates between the containers and the [gamma]-camera. The detectable radiation was regulated in accordance with automated computer-controlled step motors to move the attenuators to simulate a given patient situation. The reproducibility of the phantom measurements was defined as a coefficient of variation. Four different kidney-function simulations were repeated 3 times, and 6 parameters were compared. Results: The average root mean square deviation of the coefficient of variation was 6.7% for the perfusion integral, 1.3% for time to reach the maximum activity, 19.7% for mean transit time, 3.3% for function (Patlak [%]), 1.0% for outflow index (%), and 6.5% for time to reach the half-activity from maximum. Conclusion: With this phantom, the true values of most parameters measured are well known; it closely approaches true extraction, washout, and attenuation properties and curves, and the images produced are similar to those of patient studies. Compared with the first manual version, this new automated phantom is easy to use. Any desired clinical situation can be programmed. It is a promising tool for quality assurance and calibration of renography.
Key Words: phantom; renography; [gamma]-camera; radionuclide imaging
J Nucl Med 2004; 45:495-499
The availability of different radiopharmaceuticals, multiple quantitative parameters, and variable acquisition and processing protocols makes renal imaging a complex subject (1). Quantitative functional parameters assessed by different institutions are not always comparable. Standardization of nuclear medicine procedures is essential, and the entire diagnostic imaging chain needs to routinely be evaluated and developed. International consensus reports (2) can and should be used as a gold standard.
With the need for quality control in nuclear medicine, the need for correct use of instrumentation and objective comparisons with interlaboratory clinical studies is evident. Most parts of the imaging chain have to be considered in multicenter comparisons. Computer-simulated data (i.e., hybrid phantoms) (3,4) are usually...