For imaging a fiberglass cast, what adjustment to the X-ray technique is recommended?

For imaging a fiberglass cast, what adjustment to the X-ray technique is recommended?

• A. Decrease mA by half
• B. Increase mA by 1.5x
• C. Increase kVp by 20
• D. Use the same technique as for plaster casts

Answer: (B)

The main idea is that immobilization casts change how much X‑ray energy reaches the detector, so you adjust exposure to maintain adequate bone detail through the cast. Fiberglass casts are less dense than plaster, but they still attenuate the beam enough to dull the image of the underlying bone if you stick with the same technique used for uncast limbs. Increasing the mA by about 1.5 times raises the number of photons reaching the detector, improving image density behind the cast and helping you visualize the bone and any fracture lines more clearly without disproportionately lowering contrast. Using the same technique as plaster would overestimate the attenuation and typically require even higher exposure, while decreasing exposure or increasing kVp alone would either underpenetrate or reduce contrast, making subtle fractures harder to see. So boosting the mA by roughly 50% is the practical adjustment to get a reliable image through a fiberglass cast.

The main idea is that immobilization casts change how much X‑ray energy reaches the detector, so you adjust exposure to maintain adequate bone detail through the cast. Fiberglass casts are less dense than plaster, but they still attenuate the beam enough to dull the image of the underlying bone if you stick with the same technique used for uncast limbs. Increasing the mA by about 1.5 times raises the number of photons reaching the detector, improving image density behind the cast and helping you visualize the bone and any fracture lines more clearly without disproportionately lowering contrast.

Using the same technique as plaster would overestimate the attenuation and typically require even higher exposure, while decreasing exposure or increasing kVp alone would either underpenetrate or reduce contrast, making subtle fractures harder to see. So boosting the mA by roughly 50% is the practical adjustment to get a reliable image through a fiberglass cast.