CT fluoroscopy

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 localisation accuracy
• CT fluoroscopy requires special techniques for image reconstruction, due to the need for rapid imaging feedback

See also

• image reconstruction in CT fluoroscopy
• radiation dose considerations in CT fluoroscopy