MODULE 5 -Fluoroscopy

Flashcards based on Fluoroscopy Lecture Notes

What is the main purpose of fluoroscopy?

To provide real-time dynamic imaging of the body, often using contrast media.

What are some similarities between fluoroscopy and general x-ray machines?

Both use the same x-ray tube style (tungsten anode, filaments) and digital image receptor systems.

How does fluoroscopy differ from general x-ray imaging?

Uses lower output generators, 1–5 mA current, time controlled by exposure switch, and continuous imaging.

What is the purpose of an image intensifier?

To enhance image brightness for better visualization.

What material is the input phosphor made of, and what does it do?

Cesium iodide (CsI); it converts x-rays into light.

What does the photocathode do in an image intensifier?

Converts light into electrons.

What do electrostatic lenses do in fluoroscopy?

Focus and accelerate electrons toward the output phosphor.

What material is the output phosphor made of, and its function?

Zinc cadmium sulfide; converts electrons back into light.

How much does magnification increase patient dose in fluoroscopy?

By approximately a factor of 2.2.

What is the purpose of Automatic Brightness Control (ABC)?

Maintains consistent image brightness during varying patient thickness.

How does ABC adjust brightness?

By detecting output light and adjusting kV or mA through a feedback loop.

Name 4 common image artifacts in fluoroscopy.

Image lag, vignetting, pincushion distortion, S-distortion.

What causes pincushion distortion?

The curved surface of the image intensifier.

What causes S-distortion in fluoroscopy?

External electromagnetic interference affecting electron paths.

What features are included in digital fluoroscopy systems?

Last image hold, collimation lines, automatic rate controllers.

What are the advantages of flat panel detectors in fluoroscopy?

No distortion, consistent image quality, smaller/lighter, no cassettes.

What is the minimum lead equivalent for personnel lead aprons?

0.5 mm Pb equivalent.

What is the lead requirement for bucky slot covers and protective curtains?

0.25 mm Pb equivalent.

Why are low dose settings and pulsed fluoroscopy used?

To reduce radiation exposure for both patient and technician.

What role does a CCD play in fluoroscopy systems?

Provides fast image readout with quick response times.

What does the exposure switch control in fluoroscopy?

It controls the duration of exposure; image is only produced while the switch is held.

What mA current range is typical for image intensifier systems?

1–5 mA.

What mA range do digital flat panel detectors typically use in fluoroscopy?

Higher mA ranges than image intensifier systems.

What happens at the anode in an image intensifier?

It aids electron crossover at the focal point, impacting magnification and image sharpness.

What is “last image hold” in digital fluoroscopy?

The system displays the last fluoroscopic image without additional radiation exposure.

What is vignetting in fluoroscopic imaging?

A decrease in image brightness at the edges compared to the center.

What causes image lag in fluoroscopy?

Continued light emission from the phosphors after x-ray exposure ends.

What equipment components are typically part of a fluoroscopy system?

Computer, TV monitor, grid, x-ray tube, flat panel detector.

How do digital flat panel detectors work in fluoroscopy?

They convert x-ray photons directly or indirectly into electrical signals for image creation.

What are TFTs in fluoroscopy, and what do they do?

Thin-Film Transistors; they collect and transmit electrical signals from flat panel detectors.

What are the benefits of using CCDs in fluoroscopy systems?

Fast response times, rapid image readout, and improved temporal resolution.

Why is grid use important in fluoroscopy?

To reduce scatter radiation and improve image contrast.

What is the role of collimation lines in digital fluoroscopy?

To visually limit the x-ray beam to the area of interest and reduce unnecessary exposure.

What happens during the “pulse rate” function in fluoroscopy?

The x-ray beam is emitted in pulses instead of continuously, reducing dose.

What fluoroscopy feature automatically adjusts imaging based on patient thickness?

Automatic Brightness Control (ABC).

What fluoroscopy component is affected most by electromagnetic fields, causing distortion?

Electrons in the image intensifier, resulting in S-distortion.