A more efficient, radiation-free alternative to systematic chest x-ray for the detection of embolized seeds to the lung.
OBJECTIVE
To evaluate the efficacy of a seed-migration detector and to compare its performance to fluoroscopy and postoperative chest radiographs.


METHODS
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.
Morrier
Janelle
J
Département de radio-oncologie et Centre de recherche en cancérologie de l'Université Laval, Hôtel-Dieu de Québec, Québec, Canada. janelle.morrier@mail.chuq.qc.ca
Chrétien
Mario
M
Martin
André-Guy
AG
Vigneault
Eric
E
Beaulieu
Luc
L
D001918:Brachytherapy / Q000009:adverse effects* / Q000295:instrumentation; D002138:Calibration; D005188:False Negative Reactions; D005471:Fluoroscopy; D005548:Foreign-Body Migration / Q000150:complications / Q000000981:diagnostic imaging*; D015902:Gamma Cameras; D006801:Humans; D007457:Iodine Radioisotopes; D008168:Lung; D008297:Male; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000209:etiology; D011877:Radionuclide Imaging
D007457:Iodine Radioisotopes