Which of the following radiographic examinations is known to deliver a fetal dose exceeding 10 mGy?

The lumbar spine series is known to deliver a fetal dose exceeding 10 mGy primarily due to the extent of radiation utilized in imaging the lower back region, which involves multiple views and corresponding X-ray exposure. The anatomical depth and the amount of tissue that the X-rays must penetrate in a lumbar spine series contribute to a higher dose compared to other radiographic examinations.

In the context of fetal protection from radiation, special consideration is given to examinations that can result in doses above certain thresholds, as significant exposure may pose risks during pregnancy. Radiographic procedures like the lumbar spine series, which targets deeper structures and utilizes additional imaging parameters, lead to increased radiation dose to surrounding tissues, including the fetus, especially in cases where the uterus is involved.

Fetal doses from procedures like chest X-rays and abdominal X-rays typically remain below this threshold due to their more limited exposure fields and techniques aimed at minimizing patient radiation dose. Pelvic ultrasound, being a non-radiative diagnostic tool, does not contribute to fetal radiation at all, making it significantly less concerning in terms of fetal dose. Therefore, understanding the varying impacts of different radiographic examinations on fetal exposure is crucial in minimizing the risks associated with radiation imaging during pregnancy.