Flat Panel Detector or Image Intensifier: Comparing Fluoroscopy Receptors

How image intensifier fluoroscopy works

An image intensifier (II) is a vacuum tube. X-rays strike an input phosphor, the light is converted to electrons, accelerated and focused onto a small output phosphor, and a camera captures the bright small image that is shown on a monitor. The input diameter, commonly in inches, defines the field of view, and magnification modes use a smaller part of the input screen.

The technology is mature and well understood. Its drawbacks come from the physics: the curved input screen and electron optics create some geometric distortion, the image can lose brightness at the edges, and the output depends on the camera chain.

How a flat panel detector differs

A flat panel detector (FPD) is a solid-state plate that converts X-rays directly or through a scintillator into an electronic signal pixel by pixel. There is no vacuum tube or camera, no geometric distortion and no edge vignetting, and the image is natively digital. Our article on flat panel detector types explains the technologies.

Dynamic panels read out many frames per second at low noise, so they can serve both radiography and fluoroscopy. Villa's Apollo DRF, for example, uses a 43 × 43 cm dynamic detector for radiography and continuous or pulsed fluoroscopy, and Perlove's PLD9600D uses a 17 × 17 inch dynamic panel with pulsed fluoroscopy at 25 frames per second.

Distortion, dynamic range, dose and size

The main image advantages of FPDs are absence of geometric distortion, a rectangular field and a wide dynamic range, which helps when the image contains both thick and thin anatomy. They usually need less service for the detector itself, while II brightness and the camera chain can degrade with age.

On dose, the picture is more nuanced. A modern FPD can deliver a comparable or better image at the same or lower dose, but the result depends on the pulse rate, filtration and the technique curve, not only on the receptor. Ask for dose-rate and image-quality measurements from the system you are considering. Physically, a flat panel is slim, so tables can be lower and rooms more flexible.

Compare running costs separately: for an II this means replacing the tube and camera as they age, while for a panel the risks are damage from impact and the cost of detector replacement. Include these items in the lifetime cost calculation.

• Geometry: FPD has no distortion; II has some
• Dynamic range: wider on FPD
• Space: FPD is slim; II and camera need volume
• Digital workflow: native on FPD

Cost, lifetime and when to upgrade

An FPD system usually costs more at purchase, but over its lifetime the cost balance depends on service, replacement parts and the productivity of the room. A detector is expensive to replace, so check the warranty and the replacement terms. An II-based system may still be adequate for low-volume, simple examinations.

Consider upgrading when the II image has degraded, spare parts are hard to obtain, you want advanced applications such as DSA, stitching or tomosynthesis, or you need a single detector for radiography and fluoroscopy. See our article on flat panel detectors in fluoroscopy for the parameters to compare.

Questions to ask before choosing

Ask for the detector size, frame rates, dose-rate curves, DQE and MTF data, DAP display, DICOM support and the upgrade path. Request a demonstration with your own typical examinations, and involve your physicist in acceptance testing.

Check the current UAE device registration and radiation licensing requirements with the relevant authorities. To compare options for your department, contact Beckfinity.