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Excerpt

Computer-assisted surgery can result in improved accuracy of implant insertion and a reduction in radiation exposure to both the patient and surgeon. This article attempts to quantify the reduction of radiation doses during spine surgery in 4 different types of computer-assisted surgical procedures. While radiation exposure to the patient is important, also of importance is the cumulative radiation exposure to the surgeon who may use these techniques on a daily basis. An article by Rampersaud et al1 showed a high intraoperative occupational radiation exposure with the standard thoracoscopic-guided insertion of pedicle screws, and the significance of this current study is that this radiation exposure can be significantly reduced through the use of the Iso-C3D C-arm scanner (Siemens, GER). The improved accuracy and insertion of implants has been studied elsewhere2–4 and is not the focus of this article.
This study evaluated 4 techniques: (1) standard fluoroscopic-guided insertion; (2) a computerized tomography based computer navigation system in which a preoperative computerized tomography scan of the patient’s surgical area is obtained but requires intraoperative standard fluoroscopic imaging for registering each vertebra; (3) 2-dimensional fluoroscopic-based navigation, which provides the surgeon with up to 4 planes of visualization and requires calibrated single C-arm shots in which the instruments are visualized (the patients’ vertebrae need only 2–3 C-arm shots); and (4) the newest technique, that of an Iso-C3D C-arm system. This C-arm goes through a 190° scan and acquires 50–100 2-dimensional frames in 1–2 minutes. Reconstructions show the bony anatomy in the coronal, sagittal, and axial planes, and the surgeon can use these to guide the instruments.
The data in the article (Tables 1, 2) show that the median time of radiation and dosage is progressively decreased with these 4 techniques, with the Iso-C3D C-arm having the least. It is important to realize that the authors could only study the radiation dosage at the source of the radiation. Because of technical difficulties, they could not study the dosage on the receiver side, or to the patient. Having said this, it is probably most important to study the radiation being delivered from the source as far as the surgeon and patient are concerned.
It is noteworthy that this study only evaluated patients with spine fractures. The study needs to be repeated in patients with a coronal or sagittal plane deformity before those results can be extrapolated. Another potential problem that must be addressed before changing our standard of practice is the accuracy of the screw placement with the Iso-C3D C-arm navigation system, which was not studied in this article. The reduction of radiation dosage is extremely encouraging and of utmost importance, but we need to maintain the accuracy of screw insertion. In summary, I commend the authors on a very important contribution to the literature. I encourage them to continue their work and assess the accuracy of implant insertion, and also the radiation exposure and accuracy in patients with deformity.

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