CAMRT Fluoroscopy and Interventional Radiography 2 — Questions and Answers
Question 1: During an upper GI series, which contrast agent should be used when bowel perforation is suspected?
- High-density barium sulfate suspension
- Water-soluble iodinated contrast medium (Correct answer)
- Low-density barium paste
- Air contrast (double contrast) alone
Correct answer: Water-soluble iodinated contrast medium
Water-soluble iodinated contrast is used when perforation is suspected because barium sulfate in the peritoneal cavity causes severe granulomatous peritonitis; iodinated agents are absorbed and excreted safely.
Question 2: During a double-contrast barium enema, which patient position is used to allow barium to flow from the sigmoid colon into the cecum?
- Left lateral decubitus
- Prone position
- Right lateral decubitus (Correct answer)
- Reverse Trendelenburg
Correct answer: Right lateral decubitus
The right lateral decubitus position uses gravity to direct barium flow from the descending colon and sigmoid into the cecum, which lies in the right lower quadrant.
Question 3: What does 'pulsed fluoroscopy' mean, and what is its primary benefit?
- Alternating between high and low kVp to enhance contrast
- Delivering X-rays in discrete pulses rather than continuously, significantly reducing patient dose (Correct answer)
- Rapidly acquiring sequential spot images for cine analysis
- Using grid pulsing to suppress scatter radiation
Correct answer: Delivering X-rays in discrete pulses rather than continuously, significantly reducing patient dose
Pulsed fluoroscopy produces X-rays only during brief discrete pulses, displaying each frame as a hold until the next pulse, which can reduce patient dose by 50–90% compared to continuous fluoroscopy.
Question 4: In a hysterosalpingogram (HSG), contrast medium is instilled through which route?
- Directly into the fallopian tubes via laparoscopic cannula
- Through the cervix into the uterine cavity, with flow into the tubes demonstrating patency (Correct answer)
- Into the peritoneal cavity via transabdominal puncture
- Intravenously to opacify the uterine vasculature
Correct answer: Through the cervix into the uterine cavity, with flow into the tubes demonstrating patency
HSG involves transcervical catheter placement to fill the uterine cavity with contrast; free spill from the fimbriated ends of the fallopian tubes into the peritoneum confirms tubal patency.
Question 5: Which geometric artifact is characteristic of image intensifier-based fluoroscopy systems?
- Quantum mottle at the image periphery
- Pincushion distortion caused by the curved input phosphor projecting onto a flat output phosphor (Correct answer)
- Heel effect creating brightness gradient across the image
- Motion unsharpness due to long exposure times
Correct answer: Pincushion distortion caused by the curved input phosphor projecting onto a flat output phosphor
Pincushion distortion arises because straight lines passing near the periphery of the curved image intensifier input screen appear to bow inward, creating a characteristic warping of peripheral structures.
Question 6: During a micturating cystourethrogram (MCU/VCUG), what are the two primary diagnostic aims of the examination?
- To measure bladder capacity and assess renal function
- To evaluate urethral anatomy and detect vesicoureteral reflux during voiding (Correct answer)
- To determine post-void residual and classify bladder calculi
- To assess bladder wall thickness and detect mucosal polyps
Correct answer: To evaluate urethral anatomy and detect vesicoureteral reflux during voiding
The MCU is designed to evaluate the urethra for strictures or abnormalities during voiding and to detect vesicoureteral reflux, in which contrast flows retrograde from the bladder toward the kidney.
Question 7: What safety principle does the fluoroscopic 'dead man switch' enforce?
- It triggers an emergency shutdown of the entire X-ray generator on release
- It requires continuous operator pressure to maintain X-ray production, preventing inadvertent prolonged exposure (Correct answer)
- It automatically logs total fluoroscopy time to the PACS system
- It prevents accidental patient movement by locking the table
Correct answer: It requires continuous operator pressure to maintain X-ray production, preventing inadvertent prolonged exposure
The dead man switch requires the operator to continuously depress a footswitch or hand control to sustain fluoroscopic exposure; releasing it immediately terminates X-ray production, ensuring deliberate and active operator intent.
CAMRT Fluoroscopy and Interventional Radiography 2
During an upper GI series, which contrast agent should be used when bowel perforation is suspected?