Radiography Flashcards

Which type of grid is most effective at removing off-angle scatter?

Answer: Crossed grid

A crossed grid (two parallel grids at 90° to each other) removes scatter in all directions and is the most effective type, though it requires precise patient/tube alignment.

Which projection of the lumbar spine best demonstrates the zygapophyseal (facet) joints on the side CLOSEST to the image receptor?

Answer: Oblique projection toward the IR side

In lumbar spine obliques, the facet joints closest to the IR (downside) are demonstrated on the RPO/LPO projection toward that side.

A radiographer notices that a patient's blood pressure is 90/60 mmHg and the patient is diaphoretic. What is the BEST initial action?

Answer: Notify the radiologist or supervising physician immediately

Hypotension (90/60) with diaphoresis may indicate shock or a serious medical event; the radiographer must immediately notify the supervising physician.

Which anatomical landmark is used to center the CR for a PA projection of the hand?

Answer: Third MCP joint

For a PA hand projection, the central ray is directed to the third metacarpophalangeal (MCP) joint to center the image of all five digits.

Which type of contrast agent is used to evaluate the large intestine for suspected polyps?

Answer: Barium sulfate double-contrast enema

A double-contrast barium enema uses barium sulfate to coat the mucosal surface and air to distend the colon, providing optimal visualization of small polyps.

What is the maximum permissible occupational dose (MPD) to the whole body per year according to NCRP guidelines?

Answer: 50 mSv (5,000 mrem)

The NCRP recommends a maximum occupational whole-body dose of 50 mSv (5,000 mrem) per year for radiation workers.

Which artifact in digital radiography appears as a grid-like pattern across the image due to anti-scatter grid frequency matching the detector?

Answer: Moiré artifact

A Moiré artifact occurs when the frequency of the anti-scatter grid lines resonates with the sampling frequency of the digital detector, producing a striped interference pattern.