Fast film is characterized by what advantage?

Fast film is characterized by higher radiosensitivity, which means it requires less exposure to radiation to produce an image. This is a crucial advantage in radiography, as it allows for quicker imaging with reduced radiation doses to both patients and healthcare workers. The increased sensitivity of fast film is achieved through the use of larger silver halide crystals in the emulsion, enabling it to capture more photons in a shorter amount of time.

This characteristic is especially beneficial in scenarios where minimizing radiation exposure is a priority, such as in pediatric radiology or when conducting multiple imaging exams in a short period. Higher radiosensitivity also contributes to improved image quality in lower-dose situations, allowing for clearer images without needing to increase radiation levels.

In contrast, the other options suggest advantages that are not inherent to fast film. Greater durability relates more to physical properties rather than sensitivity, while lower cost and longer shelf life are not specific advantages tied to the film's sensitivity. Each of those aspects can vary independently based on the film type, manufacturer, and storage conditions.