Which exposure factors would best eliminate prominent pulmonary vascular markings in the RAO position of the sternum?

To eliminate prominent pulmonary vascular markings in an imaging study, particularly in the right anterior oblique (RAO) position of the sternum, using a lower milliampere (mA) setting is essential. This technique helps reduce the overall radiation dose and, consequently, minimizes the exposure of the vasculature to the imaging beam, which can otherwise enhance vascular markings due to increased contrast.

The choice to use 25 mA is strategic as it provides a gentle exposure that reduces the likelihood of overwhelming the image with vascular detail. The longer exposure time of 7/10 seconds allows for enough sensitivity to detect the sternum clearly while maintaining minimal highlight on the vascular structures. The kV setting at 70 kV also ensures sufficient penetration for the structures of interest without significantly increasing image contrast, which enhances the visibility of the vascular markings when higher contrast is used.

Together, these exposure factors effectively manage image quality while achieving the goal of diminishing prominent vascular markings, making this combination the best choice among the available options.