Final answer:
The savings in patient dose can be achieved because the collimation size (cm) is changed by a greater ratio than the SID.
Step-by-step explanation:
The savings in patient dose can be achieved because the Tube current (mA) is changed by a greater ratio than the Source-to-Image Distance (SID). You can think of the tube current as the quantity of X-ray photons produced in a given exposure. Therefore, by adjusting the mA, we can significantly alter the dose received by the patient without significantly affecting the quality of the image.
Moreover, to physically limit radiation doses, we employ techniques like shielding, increasing the distance from the source, and limiting the exposure time. These strategies work to protect both the patient and the technician during a procedure like taking an X-ray.
Furthermore, techniques like collimation and proper focal spot size can play an important role in limiting patient dose while maintaining image quality. Collimation helps shape the X-ray beam and limit its spread to non-targeted regions, while a smaller focal spot size results in better spatial resolution in the X-ray image.
Learn more about Tube current and dose saving