The lowest intensity of scatter radiation from the patient is located:

The lowest intensity of scatter radiation from the patient is located:

• A. At the foot of the table
• B. At the head of the table
• C. At a 90-degree angle from the patient
• D. At a 180-degree angle from the patient

Answer: (C)

Scatter radiation from the patient varies with angle to the primary X-ray beam. The lowest intensity occurs at a right angle to the beam, a 90-degree angle relative to the patient. This is because most scattered photons are deflected in directions closer to the beam and are more readily attenuated as the deflection angle increases toward 90 degrees, making fewer reach that side. Behind the patient (180 degrees) and along the table ends are directions where more scatter can reach due to the angular distribution and tissue interactions, so those positions aren’t the minimum. Thus the side position—perpendicular to the beam—has the least scatter.

Scatter radiation from the patient varies with angle to the primary X-ray beam. The lowest intensity occurs at a right angle to the beam, a 90-degree angle relative to the patient. This is because most scattered photons are deflected in directions closer to the beam and are more readily attenuated as the deflection angle increases toward 90 degrees, making fewer reach that side. Behind the patient (180 degrees) and along the table ends are directions where more scatter can reach due to the angular distribution and tissue interactions, so those positions aren’t the minimum. Thus the side position—perpendicular to the beam—has the least scatter.