Measurement of the radiation dose to the skin of the anterior chest is a reasonable indicator of:

• A. thyroid dose
• B. breast dose
• C. probability of cataracts
• D. depression of lymphocytes

Answer: (B)

The skin entrance dose on the front of the chest is a practical proxy for the dose received by breast tissue during chest radiography. Because the breast lies just beneath that anterior chest skin, the energy deposited in the skin closely tracks the energy reaching the breast tissue when the X-ray beam enters from the front. This makes the anterior chest skin dose a reasonable indicator of breast dose, useful for dose assessment and optimization of chest exams. The thyroid would be affected more by exposures in the neck region, cataracts relate to dose to the eye lenses from head/eye exposures, and lymphocyte depression is a systemic effect tied to overall body dose rather than a localized chest measurement.