CAT/CT guided biopsies and other minimally invasive interventions are well established medical procedures. Since the beginning of computed tomography, conventional CAT/CT imaging studies has been used to guide an interventional procedure such as a tissue biopsy of a suspected tumor or metastases.
Advanced interventional CT scanners provide fluoroscopic techniques allowing additionally the guidance of minimally invasive surgery or micro-therapy. Fluoro CT allows the continuous monitoring of the needle trajectory or inserted surgical instrument. A wide gantry opening, external tilting laser for needle guidance and special software ease the intervention.
CT images are also used to plan radiotherapy cancer treatment and determine how the disease is responding to the treatment.

A fluoroscope projects x-ray images in a video sequence (movie) onto a screen monitor.
Early generation fluoroscopes presented particularly difficult viewing challenges for radiologists. The human retina contains two types of image receptors. Cones (central vision) operate better in bright light, while rods (peripheral vision) are more sensitive to blue-green light and low light. Therefore, the radiologists wear red goggles to filter out blue-green wavelengths to allow the rods to recover peak sensitivity before viewing fluoroscopic images.
To avoid this time consuming accommodation, the industry developed the image intensifier tube in the 1950s. Due to the high amount of individual images during a fluoroscan, a very sensitive amplifier is needed to cut down radiation exposure. Until today, image intensifiers amplify the faint light emitted by the fluorescing screen and the images can be viewed on a monitor. Recently, digital technique replaces the large and bulky image intensifier with flat-panel technology.
Various other components of a fluoroscope system include a gantry, patient table, x-ray tube, filters, collimators, images sensor, camera and computer, most similar to other radiographic systems.
A fluoroscopy system provides the view of moving anatomic structures and is valuable in performing procedures that require continuous imaging and monitoring, such as barium studies, gastrointestinal function tests, cardiac functions, studies of diaphragmatic movement, or catheter placements. A number of technologies are available to record images created during fluoroscopic (fluorographic) exams.

When invented, a fluoroscopic system consisted of x-ray tube, fluorescent screen and x-ray table. In 1950's, the development of the image intensifier revolutionized fluoroscopes. The basic components are extended by a gantry, image intensifier, camera, film and monitor system. The x-ray tube is usually located under the patient table, in opposition to the image intensifier and film cassette or display unit. The patient table can be rotated to an upright position for certain examinations and can be lowered to horizontal position for other imaging procedures. In some instances, the unit can be operated from outside the room.
Today, the transition from conventional to digital fluoroscopy replaces the image intensifier. A flat-panel detector in combination with sensitive image sensors and digital image processing improves the diagnostic ability of a modern system.

(FID) The focus to isocenter distance is the distance from the focus of the x-ray tube to the isocenter (the rotation center of the CT gantry).

A slice is a tomographic section of an object. A slice is defined by position and thickness; each slice is divided into a matrix of voxels. In computed tomography, a motorized table slips the patient through the gantry and slices are made when the x-ray tube rotates in a circle around the patient.