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A dynamic phantom for radionuclide renography

The aim of the study was to develop and test a dynamic phantom simulating radionuclide renography. The phantom consisted of five partly lead covered plastic containers simulating kidneys, heart, bladder and background (soft tissues, liver and spleen). Dynamics were performed with multiple movable steel plates between containers and a gamma camera. Control of the plates is performed manually with a stopwatch following exact time schedules. The containers were filled with activities (Tc) which produce count rates close to clinical situations. Count rates produced by the phantom were compared with ten clinical renography cases: five Tc MAG3 and five Tc DTPA examinations. Two phantom simulations were repeated three times with separate fillings, acquisitions and analyses. Precision errors as a coefficient of variation (CV) of repeated measurements were calculated and theoretical values were compared with the corresponding measured ones. A multicentre comparison was made between 19 nuclear medicine laboratories and three clinical cases were simulated with the phantom. Correlations between count rates produced by the phantom and clinical studies were r = 0.964 for Tc MAG3 ( p < 0.001) and 0.961 for Tc DTPA ( p < 0.001). The precision error was % and the percentage difference between theoretical and measured values for was %. Images and curves of the scanned phantom were close to a real patient in all 19 laboratories but calculated parameters varied: the difference between theoretical and measured values for was %. The difference between laboratories is most probably due to variations in acquisition protocols and analysis programs: 19 laboratories with 18 different protocols and 8 different programs. The dynamics were found to be repeatable and suitable for calibration purposes for radionuclide renography programs and protocols as well as for multicentre comparisons.