Interdepartmental audit with an anatomically realistic lung phantom

The diagnostic proficiency of nuclear medicine professionals and the accuracy of equipment may be tested with phantoms. All phases of the imaging chain should be included in the external quality assurance of imaging.

The aim of this study was to evaluate and compare the quality of nuclear imaging of the lung in Finland. For this purpose, we developed a new anatomically realistic lung phantom. The phantom consisted of plastic containers filled with plastic pellets to imitate the 3-dimensional shape of the lungs. These containers were filled with radioactive liquid and placed inside an anatomically accurate phantom of the chest cavity. The attenuation properties of the phantom were close to those of a real human thorax. Perfusion and ventilation defects were positioned inside the phantom to mimic 2 clinical cases. The phantom was imaged and interpreted as a patient simulation study in 18 Finnish hospitals. Reconstruction, printout, and reporting were according to the clinical routine of each hospital. The quality of the image sets and reports was evaluated and scored from 0 to 10. Additionally, technical performance was evaluated by a nuclear medicine specialist and hospital physicians.

The average score (+/-SD) for overall quality was 7.1+/-1.1 (range, 5.2-8.5). Reports received a score of 7.2+/-1.7 (4.7-10.0); image sets, 7.2+/-1.3 (4.8-9.7), technical evaluation by hospital readers, 6.5+/-2.3 (1.6-9.5); and technical evaluation by a specialist, 7.8+/-1.2 (5.7-10.0).

Lung imaging routines and the results of this survey were diverse. None of the participating hospitals routinely used tomography. In planar imaging, the most valuable projections were oblique (left anterior oblique, right anterior oblique, left posterior oblique, and right posterior oblique) and straight sides (right and left). The phantom mimics variable clinical situations well and is suitable for testing of imaging protocols and for proficiency testing of nuclear medicine professionals and equipment. Clinical phantom studies are an effective way of assessing an imaging program.