How can scatter radiation be minimized besides collimation?

• A. Use grids, increase distance as feasible, proper shielding, and optimal exposure factors.
• B. Increase kVp without limits.
• C. Use larger fields.
• D. Ignore shielding practices.

Answer: (A)

Scatter degrades image contrast, so the goal is to reduce photons that bounce around inside the patient and reach the detector. You can do this beyond collimation by using a grid to absorb scattered photons, increasing distance so more scatter misses the detector (air gap or greater SID, with a trade-off in sharpness and exposure that you compensate for), applying proper shielding to reduce irradiated tissue and thus the amount of scatter produced, and selecting exposure factors that minimize scatter while still producing a diagnostic image (the right balance of kVp and mAs for the exam).

Grids physically absorb much of the scatter before it reaches the image receptor, though they require higher exposure to maintain receptor brightness. Increasing distance reduces the likelihood that scattered photons will strike the detector, but can magnify the image and lower sharpness, so it’s used judiciously. Shielding limits the volume of tissue irradiated, thereby reducing scatter generation. Choosing optimal exposure factors helps keep the primary beam effective for the image while limiting scatter production.

Using higher kVp without limits would increase scatter and reduce contrast; larger fields increase scatter; ignoring shielding practices would raise both patient dose and scatter.