When using a portable C-arm for an anteroposterior chest view, where is the most scattered radiation?

The correct answer highlights the physics of radiation scatter in relation to the primary beam during fluoroscopic procedures. When using a portable C-arm, the primary beam is directed through the patient's body, and scattered radiation is produced as the beam interacts with tissue. The intensity of scattered radiation decreases as you move away from the primary beam, but there are specific angles where it becomes more pronounced.

Scattered radiation is most intense at angles that are perpendicular to the direction of the primary beam. In this context, the most significant scatter occurs at 90 degrees, but as the question specifies using a C-arm for a chest view, the geometry involved suggests that the highest levels of scatter radiation occur further from the primary beam's line of travel—around 135 degrees. This angle represents an area where the scattered photons emitted from the patient are at their peak because they are dispersed in multiple directions as they bounce off tissues.

In practice, understanding the distribution of scattered radiation is crucial for protecting both the operators and any nearby personnel from unnecessary exposure. This knowledge helps in making informed decisions about positioning during procedures and the placement of lead shielding.