CAMRT Fluoroscopy and Interventional Radiography 1 — Questions and Answers
Question 1: What is the primary characteristic that distinguishes fluoroscopy from conventional radiography?
- It uses a lower kVp than conventional radiography
- It provides real-time, continuous X-ray imaging (Correct answer)
- It requires significantly higher mAs than static imaging
- It eliminates the need for radiation protection measures
Correct answer: It provides real-time, continuous X-ray imaging
Fluoroscopy provides real-time, continuous X-ray imaging, allowing visualization of dynamic physiological processes such as swallowing or vessel flow.
Question 2: In a conventional image intensifier, what is the correct sequence of conversions that produces a visible fluoroscopic image?
- X-rays → input phosphor (light) → photocathode (electrons) → output phosphor (light) → TV camera (Correct answer)
- X-rays → electrons → light → TV camera
- X-rays → photocathode → input phosphor → electrons → TV camera
- X-rays → TV camera → phosphor → electrons
Correct answer: X-rays → input phosphor (light) → photocathode (electrons) → output phosphor (light) → TV camera
The image intensifier converts X-rays to light via the input phosphor, then to electrons via the photocathode; electrons are accelerated to the output phosphor, producing a bright, minified image captured by the TV camera.
Question 3: What is the typical entrance skin dose rate range during standard fluoroscopy?
- 0.01–0.1 mGy/min
- 1–10 mGy/min (Correct answer)
- 50–100 mGy/min
- 500–1000 mGy/min
Correct answer: 1–10 mGy/min
Standard fluoroscopy delivers entrance skin dose rates of approximately 1–10 mGy/min, though high-dose-rate fluoroscopy modes can exceed this range.
Question 4: What is the function of the 'last image hold' (LIH) feature in fluoroscopic equipment?
- It permanently archives all fluoroscopic frames to PACS
- It displays the most recently acquired fluoroscopic frame as a static image without ongoing radiation (Correct answer)
- It reduces the image refresh rate to lower dose during dynamic runs
- It automatically records a cine loop of the entire procedure
Correct answer: It displays the most recently acquired fluoroscopic frame as a static image without ongoing radiation
LIH captures and displays the last acquired fluoroscopic frame as a static image, allowing the operator to review the image without continuing to expose the patient to radiation.
Question 5: What is the primary purpose of the automatic brightness control (ABC) system in a fluoroscopic unit?
- To adjust room ambient lighting for optimal monitor viewing conditions
- To automatically adjust kVp and/or mA to maintain consistent image brightness as attenuation changes (Correct answer)
- To control the speed at which the image intensifier rotates during the study
- To set the black-and-white contrast ratio on the display monitor
Correct answer: To automatically adjust kVp and/or mA to maintain consistent image brightness as attenuation changes
ABC automatically adjusts exposure parameters (kVp and/or mA) to compensate for changes in tissue thickness or density, maintaining consistent image brightness throughout the examination.
Question 6: During a barium swallow examination, why are multiple projections (AP, lateral, oblique) obtained rather than a single view?
- To reduce total radiation dose by spreading exposure over multiple positions
- To comprehensively evaluate esophageal anatomy and function from all angles and detect lesions that may be obscured in one view (Correct answer)
- Because a single lateral view is insufficient for contrast media flow
- To comply with mandatory CAMRT positioning protocols
Correct answer: To comprehensively evaluate esophageal anatomy and function from all angles and detect lesions that may be obscured in one view
Multiple projections are required to fully assess esophageal morphology and motility, as lesions or structural abnormalities may be hidden behind overlying structures in any single projection.
Question 7: At what cumulative fluoroscopic time does most current guidance recommend that the operator be alerted to monitor for potential high skin dose?
- 1 minute
- 5 minutes (Correct answer)
- 30 minutes
- 60 minutes
Correct answer: 5 minutes
Many regulatory and professional guidelines recommend alerting thresholds at 5 minutes of cumulative fluoroscopy time as a reference level to prompt dose monitoring and documentation in lengthy procedures.
CAMRT Fluoroscopy and Interventional Radiography 1
What is the primary characteristic that distinguishes fluoroscopy from conventional radiography?