Gonads should be shielded if they lie within what distance of the primary beam?

• A. Within 1 cm
• B. Within 3 cm
• C. Within 5 cm
• D. Within 10 cm

Answer: (C)

Gonadal shielding is used when the reproductive organs could receive a meaningful dose from the exam, since they are highly radiosensitive. The standard guideline is to shield the gonads if they lie within five centimeters of the primary beam. At that distance, the dose to the testes or ovaries from the direct beam and scattered radiation is substantial enough that shielding can meaningfully reduce their exposure without compromising the diagnostic information. If the gonads are more than five centimeters away from the beam, the exposure is typically low enough that shielding isn’t routinely required, though it may still be considered in certain cases. Ensure the shield is positioned to cover the gonads and not interfere with the area of interest, and apply shielding decisions in light of image quality and dose optimization practices.