A more efficient, radiation-free alternative to systematic chest x-ray for the detection of embolized seeds to the lung.

PURPOSE

To evaluate the efficacy of a seed-migration detector and to compare its performance to fluoroscopy and postoperative chest radiographs.

METHODS AND MATERIALS

A gamma scintillation survey meter was converted to a seed-migration detector by adding a shield on the probe detection window. The detector response to three (125)I seed activities was characterized for different source-to-detector distances in water. The detector was used to perform a chest evaluation on 737 patients at their first postoperative visit. When the detector showed positive activity, seed migration was confirmed by taking a chest radiograph and by looking at the region with fluoroscopy.

RESULTS

One hundred and three patients (14.0%) presented at least one embolized seed. This accounts for 123 of the 39,887 seeds. Eighty-seven, 12, and 4 patients had respectively one, two, and three seed embolization. Compared with the seed-migration detector, detection based on fluoroscopy would have led to 13 false-negative detections (of 103, or 12.6%), and the radiograph would have resulted in 31 or 30.1%. More important, standard chest X-ray would have required a survey and extra radiation dose to lung to 100% of the patients, rather than the 14% who required it.

CONCLUSIONS

The usual recommendation to perform chest radiographs at the first follow-up visit to scan lungs for embolized seeds should be revised because of the high false-negative rate. Scintillator-based gamma counter detector provides superior detection sensitivity and should be adopted as a standard of practice. Chest X-ray could be limited to documenting cases of positive migration.