What features of the high-transmission cellular (HTC) grid allow it to maintain equal or less radiation dose to the patient?

The high-transmission cellular (HTC) grid is designed to improve image quality in mammography while minimizing the radiation dose to the patient. The correct answer involves the use of copper strips and air interspaces.

Copper is effective in attenuating scattered radiation while allowing a high transmission of the primary beam, thereby reducing the overall radiation dose to the patient. The air interspaces are crucial because they provide a pathway for the primary x-rays to pass through while still allowing the scattered rays to be absorbed by the copper. This dual design helps in maintaining image quality and minimizing radiation exposure.

In contrast, other materials mentioned in the incorrect options do not offer the same combination of effective scatter reduction and minimal absorption of the primary beam. For example, lead strips are commonly used in traditional grids, but they absorb more of the primary beam compared to copper, which could result in a higher radiation dose. Similarly, elements like beryllium and aluminum may not have the same optimal transmission characteristics as copper in this specific application.

Thus, the combination of copper strips and air interspaces in the HTC grid effectively maintains equal or lower radiation doses while improving image quality in mammography.