SU-F-P-59: Detection of Missing Surgical Needles with Intraoperative Mobile X-Ray




To determine the minimal detectable size of a surgical needle using intraoperative mobile x-ray imaging. Also, varying techniques such as low kVp and high tube current were tested to investigate whether this improved the detection of the various needle sizes.


Seven surgical needle sizes, 6.5, 8, 11, 13, 16, 17 and 19 mm, were positioned on three regions (thoracic, abdominal and pelvic) of an adult size anthropomorphic RANDO phantom. The phantom represents an average size adult. The phantom, in front of detector, was imaged with 44” x-ray tube to detector distance. For the thoracic region, each needle size was imaged 4 times using the following technique (81 kVp at 32 mAs and 200 mAs; then 100 kVp at 32 mAs and 200 mAs. This was repeated for the abdominal and pelvic regions of the phantom. The images were reviewed by a board certified diagnostic radiologist.


The surgical needles sized 13 mm and above were visible at all three body regions using all four kVp and mAs combinations. For surgical needle sizes 8 and 11 mm, the visibility of needle was ambiguous in thoracic region and barely visible abdominal and pelvic regions. Surgical needles, with size smaller than 8 mm, could not be visualized on x-ray with unassisted eyesight. The detectability of the smaller sized needles was not improved with increasing mAs or decreasing kVp.


Surgical needle sizes less that 13 mm were not visualized with intraoperative mobile x-ray imaging using various mAs and kVp combinations. Intraoperative mobile x-ray is not recommended to locate surgical needle sizes less than 13 mm for the following reasons: (1) it prevents unnecessary radiation exposure to patient, (2) it avoids the delay time with wound closure and completion of the operative procedure, and (3) it saves radiologist reading time.