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To assess a novel Cone Beam Tomosynthesis (CBT) 3D surgical imaging modality by assessing Image Quality (IQ) and dose when compared to Cone Beam Computed Tomography (CBCT).

The CBT system operates by acquiring fast fluoro acquisitions taken in a circular tomosynthesis geometry and reconstructing a 3D volume providing near real-time 3D images of the surgical scene. Both the CBT and CBCT system have a low dose mode and a high image quality (IQ) mode. Two patient scans were performed on each system using each mode. The high IQ mode in CBT was achieved using a stereotactic acquisition. To assess IQ, an accreditation phantom (Catphan-504, Phantom Laboratory, Salem, NY) was used to quantify image quality metrics, with a focus on metrics relevant to imaging for spinal fusion procedures: geometric accuracy and high-contrast resolution. Standard noise measurements (CNR) over homogenous bony, and soft tissue regions were recorded and two metrics were computed. Uniformity metric was computed as the difference (in Hounsfield Units (HU)) between the center and the edge of an imaged homogenous module. CNR was computed as the ratio of the contrast in a bony area over the noise in the surrounding water area. To assess dose, an anatomic phantom (RANDO®, RSD Phantoms, Long Beach, CA) was outfitted with 24 OSL dosimeters (nanoDotTM, Landauer, Glenwood, IL) placed both on the surface of the lung inside the phantom, and on the skin surface. The absorbed dose was computed by combining the 24 dosimeter readings.

Initial CBT images have shown to have similar image quality when compared to CBCT. Uniformity (CBT vs CBCT) was 130.0 HU vs 92.6 HU for high IQ and 391.6 HU vs. 178.3 HU in low dose. CNR (CBT vs CBCT) was 11.0 vs 10.7 for high IQ mode. Absorbed Dose was reduced by more than 90% with CBT. (0.60mSv in CBT vs. 10.30mSv in CBCT in the low resolution mode, and 1.20mSv in CBT vs. 15.95mSv in CBCT for high resolution mode).

When looking at high contrast bony anatomy, CBT is comparable to CBCT in terms of Uniformity, CNR, and MFT with considerable less dose to the patient. CBT shows potential to provide near-real time intraoperative 3D imaging for procedures such as spinal fusion.

Cone Beam Tomosynthesis has potential to reduce dose and increase accuracy as compared to CBCT. CBT also provides an open geometry which has the potential for concurrent 3D imaging during surgery.