WE‐E‐332‐02: Dosimetric Characterization of a Cone Beam O‐Arm Imaging System

Abstract

Purpose: The O‐arm is a cone beam imaging system designed primarily to support orthopedic surgery as well as for image‐guided and vascular surgery. Using a gantry that can be opened or closed, the O‐arm can function as a 2D fluoroscopy device or collect 3D volumetric imaging data like a CT system. Our clinical applications of the O‐arm in spine surgical procedures, assessment of pedicle screw position, kyphoplasty procedures, and etc show that the O‐arm 3D mode provides enhanced imaging information in the surgical procedure compared to radiographs or fluoroscopy alone. However, the radiation dose of the O‐arm has remained uninvestigated. This study is to investigate patient dose and scatter radiation from an O‐arm and compare the results to those from a CT scanner and a conventional C‐arm. Method and Materials: The patient dose was measured using a 0.6 cc Farmer ion chamber and 30 cm long CT head and body phantoms. Scatter radiation was measured at several locations around the O‐arm, at 1m, 2m and 3m distances from the iso‐center of the O‐arm, in both the 2D fluoroscopic mode and the 3D mode with a Radcal 10×5−180 pancake ion chamber using a 30 cm long CTDI body phantom as the source of scatter. The same measurements were made for an OEC C‐arm and a 64 slice CT scanner, respectively. Results: The results show that under identical technical conditions and with the same scan length, the O‐arm 3D mode delivers radiation dose to patients and scatter dose to personnel that is comparable to that of the 64 slice CT scanner. The O‐arm 2D mode produces similar scatter radiation as a conventional GE OEC fluoroscopic C‐arm system. Conclusion: Our study demonstrated that the O‐arm had comparable radiation dose to patients and radiologists as CT and C‐arm systems.