Final answer:
The less dense breast is used for classification during mammograms to enhance tumor detection due to better contrast. MRI is also used to supplement X-rays, especially in younger women with denser breasts.
Step-by-step explanation:
When breasts are not equally dense, the less dense breast is used to make classification. This is because the increased presence of fat in the less dense breast can provide more contrast on a mammogram, making it easier to identify lumps or tumors. As women age, their breast tissue often becomes less dense, which actually facilitates the detection of tumors using X-ray diagnostics. For younger women, whose breasts are typically denser, contrast in a mammogram can be more difficult to achieve, leading to challenges in early detection. To assist in such cases, MRI (Magnetic Resonance Imaging) has been employed alongside traditional X-rays to improve the accuracy of breast cancer screening and reduce the occurrence of false positives.