Final answer:
A single mammographic projection typically delivers around 0.4 mSv, which is considered a low dose. This is comparable to other diagnostic techniques that use radiation, always balancing the risks with the benefits of obtaining a medical diagnosis.
Step-by-step explanation:
A single mammographic projection typically delivers around 0.4 mSv to the tissue affected. Various medical imaging techniques involve different levels of radiation exposure. For example, a chest x-ray has an exposure of about 0.1 mSv, while CT scans can deliver doses around 10 mSv. It's important to understand that these doses are localized to the tissue imaged, with minimal scatter to other tissues. The use of radiopharmaceuticals usually results in doses from 1 to 5 mSv. Special considerations are taken with isotopes like 131 I used in thyroid scans due to its longer half-life, resulting in higher exposures of about 0.75 Sv, while the more short-lived 123 I limits thyroid exposure to about 15 mSv. The risk from diagnostic doses of radiation must always be weighed against the medical benefits that the diagnosis provides.