Why is the dose for a 2x magnification view approximately twice that of the standard contact image using a grid?

In magnification mammography, the positioning of the breast on the magnification platform results in the breast being much closer to the X-ray tube compared to standard contact imaging. This proximity increases the amount of radiation dose received by the breast tissue because the intensity of the X-ray beam decreases with distance. According to the inverse square law, halving the distance to the source of radiation results in a fourfold increase in dose; however, in this case, the dose is specifically noted as approximately double that of the standard contact image due to factors such as lesser beam spread and concentration of the X-ray beam on the area of interest.

The other choices do not accurately address the reasons behind the increase in dose associated with magnification views in the context provided. For instance, while the use of a small focal spot can enhance image detail, it is not the primary reason for the doubling of the dose in this scenario. Similarly, the KVp settings used in magnification and contact imaging do not inherently correlate with the radiation dose in the same way that distance does. Understanding the critical role of breast position relative to the X-ray source is essential for comprehensively grasping this aspect of mammography.