**Core Concept**
The mammography examination involves the use of low-energy X-rays to produce images of the breast tissue. The radiation dose used in mammography is a critical factor in minimizing the risk of radiation-induced malignancy while maximizing diagnostic accuracy.

**Why the Correct Answer is Right**
The correct answer is 0.7 mSv. This dose is based on the guidelines set by the American College of Radiology (ACR) and the Radiological Society of North America (RSNA), which recommend a radiation dose of 0.7 mSv for a standard mammography examination. This dose is considered adequate for achieving high-quality images while minimizing the risk of radiation-induced harm. The mammography equipment is designed to deliver a low dose of radiation, typically in the range of 0.5-1.0 mSv, depending on the specific machine and examination protocol.

**Why Each Wrong Option is Incorrect**
**Option A:** 0.5 mSv is too low to achieve high-quality images in all breast tissue types, particularly in denser breasts.
**Option C:** 0.9 mSv is higher than the recommended dose and may increase the risk of radiation-induced harm without providing additional diagnostic benefit.
**Option D:** 1 mSv is higher than the recommended dose and may not be necessary for achieving high-quality images in most breast tissue types.

**Clinical Pearl / High-Yield Fact**
Radiation doses used in mammography have decreased significantly over the past few decades, from around 4 mSv in the 1970s to the current recommended dose of 0.7 mSv. This reduction in dose has greatly minimized the risk of radiation-induced harm while maintaining high diagnostic accuracy.

**✓ Correct Answer: B. 0.7 mSv**