Final answer:
The presence of a pneumothorax should prompt a radiographer to not use automatic exposure controls when taking a chest x-ray, to ensure proper imaging and to minimize unnecessary radiation exposure.
Step-by-step explanation:
The patient history information that should prompt the radiographer to decide against using automatic exposure controls when taking a chest x-ray is C. Pneumothorax. A pneumothorax involves the presence of air in the pleural space, which can alter the density of the area being imaged and thus lead to incorrect exposure settings if automatic exposure controls are used. On the other hand, while conditions such as chronic bronchitis, oat cell carcinoma (lung cancer), and emphysema have significant health implications and affect the lungs, they do not typically necessitate the manual setting of exposure on an x-ray machine as the automatic exposure controls can often compensate appropriately for these conditions.
It is crucial to understand that prolonged exposure to x-rays can lead to cell damage and increase the risk of cancer. Therefore, minimizing unnecessary radiation exposure by using appropriate exposure settings is important for patient safety.