Which method can reduce x-ray exposure by up to 50%?

The method that can significantly reduce x-ray exposure by up to 50% is the use of square cones over round cones. This reduction occurs due to the improved collimation that square cones provide. Square cones create a more focused beam of x-rays that align more closely with the area being imaged, minimizing radiation exposure to surrounding tissues. By defining the beam better, square cones can effectively limit the area being irradiated, thus lowering the overall dose received by the patient.

In contrast, increasing the mA setting typically results in a higher radiation output and greater exposure. Reducing filtration levels can lead to increased exposure by allowing more low-energy (less penetrating) radiation to reach the patient rather than filtering it out. Shortening exposure times can reduce the amount of radiation received but does not specifically relate to the method of cone shape, which directly enhances beam focus and minimizing unnecessary exposure. Thus, the use of square cones is the most effective method in this context for reducing x-ray exposure.