Image Quality and Interpretation Flashcards

Which of the following describes the relationship between OID (object-to-image distance) and magnification?

Answer: Increasing OID increases magnification

As OID increases, the object is farther from the image receptor and closer to the source, causing greater divergence of X-rays and increased magnification.

On an AP pelvis radiograph, the obturator foramina appear unequal in size. What does this indicate?

Answer: Patient rotation

Unequal obturator foramina on an AP pelvis indicate patient rotation, as both foramina should appear symmetric when properly positioned.

What does a step-wedge (penetrometer) image primarily evaluate?

Answer: The exposure latitude and contrast scale of the imaging system

A step-wedge produces a range of densities that allows evaluation of the system's exposure latitude, contrast, and density response across different exposure levels.

Which radiographic finding is most characteristic of free air (pneumoperitoneum) on an upright abdominal radiograph?

Answer: Air under the diaphragm

Free intraperitoneal air rises to the highest point in the abdomen and appears as a radiolucent crescent under the diaphragm on an upright view.

What effect does increasing the source-to-image distance (SID) have on image sharpness, assuming all other factors remain constant?

Answer: Sharpness increases because geometric unsharpness decreases

At greater SID, the X-ray beam approaches parallel rays more closely, reducing geometric unsharpness (penumbra) and improving recorded detail.

Which type of grid is designed to be used at a specific SID range and will produce grid cutoff if used outside that range?

Answer: Focused grid

A focused grid has grid lines angled to align with the divergence of the X-ray beam at a specific SID, causing cutoff artifacts if used at incorrect distances.

When reviewing an image for diagnostic quality, which criterion confirms adequate penetration on a lateral thoracic spine radiograph?

Answer: Intervertebral disc spaces are visible through the superimposed shoulders

On a lateral thoracic spine, the intervertebral disc spaces must be visible through the shoulders to confirm sufficient penetration of all superimposed structures.