Fluoroscopy – Chapter 33 Key Vocabulary

Vocabulary flashcards covering essential terms, components, safety parameters, and digital concepts from the Chapter 33 Fluoroscopy lecture.

Fluoroscopy

Dynamic imaging technique that provides real-time visualization of anatomical structures using a continuous or pulsed x-ray beam.

Static Diagnostic Radiography

Traditional x-ray imaging that produces single still images rather than real-time sequences.

Image Intensifier (II)

Vacuum tube device that converts low-intensity x-ray images into bright, visible images for viewing during fluoroscopy.

Input Phosphor

Cesium iodide scintillator layer of the II that converts incoming x-ray photons into light photons.

Scintillator

Material (e.g., CsI) that glows and emits light when struck by ionizing radiation.

Cesium Iodide (CsI)

High-efficiency phosphor used in input screens and flat-panel detectors to convert x-rays to light.

Photocathode

Cesium–antimony layer that converts light from the input phosphor into electrons in proportion to light intensity.

Electrostatic Lenses

Negatively charged rings inside the II that accelerate and focus electrons toward the output phosphor.

Anode (in II)

Positively charged (+25 kV) plate that attracts electrons toward the output phosphor.

Output Phosphor

Zinc-cadmium sulfide layer (~2.5-5 cm) that converts electrons back into a bright light image.

Brightness Gain

Overall ability of the II to increase image illumination; equal to minification gain × flux gain.

Flux Gain

Increase in brightness due to electron acceleration; ratio of output light photons to input x-ray photons.

Minification Gain

Brightness increase from compressing the light photons onto the smaller output phosphor; (input diameter² ÷ output diameter²).

Automatic Brightness Control (ABC)

Fluoroscopic system that automatically adjusts kVp and/or mA to maintain image brightness at the II.

Automatic Exposure Control (AEC)

Electronic feature that terminates exposure once sufficient radiation has reached the detector; used in ABC.

Automatic Brightness Stabilization

Alternate term for ABC highlighting maintenance of consistent image brightness.

Automatic Gain Control

System that amplifies the video signal electronically rather than changing x-ray exposure factors.

Magnification Mode

II function that shifts the focal point by increasing lens voltage to enlarge the image, improving resolution but raising patient dose.

Veil Glare

Internal light scatter in the II that lowers image contrast across the field.

Vignetting

Reduction in brightness at the periphery of an II image due to geometric and optical factors.

Charge-Coupled Device (CCD)

Semiconductor chip that converts light from the II into electronic signals for digital image capture.

Signal-to-Noise Ratio (SNR)

Measure comparing useful image signal to background noise; higher SNR equals better image quality.

Detective Quantum Efficiency (DQE)

Efficiency with which a detector converts incoming x-ray signal into a useful image; higher DQE means lower required dose.

Dead-Man Foot Switch

Spring-loaded pedal that activates x-ray exposure only while depressed, enhancing safety in fluoroscopy.

Tabletop Exposure Rate

Patient entrance skin dose during fluoroscopy, limited to 100 mGy/min (typical 10–30 mGy/min).

Source-to-Skin Distance (SSD)

Minimum required space between x-ray tube and patient skin: 38 cm (fixed) and 30 cm (mobile/C-arm).

Pulse-Progressive Fluoroscopy

Digital fluoroscopy technique using rapid on/off x-ray pulses to lower dose while maintaining image quality.

Interrogation Time

Time needed for an x-ray tube to switch on and reach preset kVp/mA (≈1 ms with high-freq generators).

Extinction Time

Time required for an x-ray tube to turn off after the exposure pulse ends (≈1 ms).

Flat Panel Image Receptor (FPIR)

Thin, lightweight cesium-iodide/amorphous-silicon detector that replaces II and CCD in digital fluoro systems.

Thin-Film Transistor (TFT) Array

Matrix of electronic switches in flat-panel detectors that collects and reads out charge from each pixel.

Amorphous Silicon (a-Si)

Photodiode material used with CsI scintillators in indirect flat-panel detectors to convert light into electrical charge.

Road-Mapping

Real-time subtraction technique where a stored mask image is subtracted from live images to guide catheter placement.

Digital Subtraction Angiography (DSA)

Imaging method that subtracts a pre-contrast mask from post-contrast images to enhance vascular detail.

Dynamic Range

Range of x-ray exposures a detector can accurately capture; wider range improves visualization of both low and high densities.

Mirror System

Early viewing method reflecting output screen image to the operator before image intensifiers became standard.

Brightness (Luminance)

Perceived light intensity of an image; increased by flux and minification gains in the II.