Computed tomography (CT) fluoroscopy combines the conventional advantages of both CT and fluoroscopy and has an important role in image-guided interventions where real-time imaging is required.
Historically, fluoroscopy was the main image guidance tool for interventional radiology procedures. The developments in CT led to it becoming an increasingly used tool in image-guided procedures e.g. chest biopsies. CT fluoroscopy combines the cross-sectional image targeting provided by CT with the real-time imaging, tracking and movement perception of fluoroscopy for interventional procedures. It allows continuous update of images at a fixed position and is commonly used for CT-guided biopsies and fluid drainages.
Advantages
overlapping structures can be removed, providing accurate spatial information
real-time display of images
consequent reduction in complications through finer needle control
reduced procedure time
increased operator confidence
Technical considerations
video monitor will need to be displayed in the scanning room
an operator panel is required in the scanning room – with controls available for table movement, gantry lift, laser light control and fluoroscopic factors. Exposures will usually be activated using a footswitch
involves an x-ray tube current of 30-50 mA, compared with conventional fluoroscopy with approximately 4 mA, or conventional CT with approximately 150-400 mA
need for additional beam filtration to decrease patient radiation exposure
consideration for radiation exposure to the interventionalist
multislice machines have finer z-axis resolution, which improves localization accuracy
CT fluoroscopy requires special techniques for image reconstruction, due to the need for rapid imaging feedback