J Wang*, S McKenney, L Phillips, Stanford University, Stanford, CA

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  J Wang

MO-C930-IePD-F8-1 (Monday, 7/11/2022) 9:30 AM - 10:00 AM [Eastern Time (GMT-4)]

Exhibit Hall | Forum 8

Purpose: Intraoperative CT scan during spine surgery provides opportunities of immediate evaluation of surgical instrument position without the need of the postoperative CT scan. In this phantom study, three imaging systems with 3D Cone-beam scanning capability were evaluated in radiation dose and image quality using clinical protocols of teenage patients.

Methods: Three imaging systems were studied: A: Ziehm RFD 3D, B: Philips Allura Xper, and C: Medtronic O-arm. Spine protocols for teenagers or slim adults were used. The “CT-like” dose metrics CTDIw was obtained using the conventional CTDI measurement methodology (32cm body phantom and a pencil ion chamber). Dose measurements in the peripheral and central locations were acquired using abdomen-shape tissue equivalent CT dose phantoms of four different sizes (CIRS phantoms). Image quality of the 3D scans was compared using the CIRS phantoms and a CT ACR phantom. CT number accuracy, image noise, image uniformity and high-contrast resolution was studied.

Results: Using the “slim patient” protocol, the CTDIw is 5.9, 20.9 and 9.01 mGy based on 32-cm CTDI phantom. The water(bone) CT number of the ACR module 1 are 57(588) HU, -37(738) HU and 328(1525) HU. In the uniformity test, the maximum CT number difference between central and peripheral locations is 102HU, 137HU and 153HU respectively. System B showed the best visualization of the 5, 6 and 7 lp/cm metal bars in the high contrast resolution module of the ACR phantom.

Conclusion: Because of the difference in scanning geometry, automatic exposure control, and default clinical protocol settings, the radiation dose magnitude and distribution vary among three systems, which also results in different image quality performance.

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