What is the primary function of a Linear Accelerator?

The primary function of a Linear Accelerator, often referred to as a linac, is to produce high-energy particles, typically electrons or protons, which are used in the treatment of cancer. These high-energy particles are directed towards tumor cells in a process known as radiation therapy. The energy delivered during treatment targets cancer cells while aiming to minimize damage to the surrounding healthy tissue.

In the context of the options provided, the focus on using high-energy protons for cancer treatment aligns explicitly with the advancements in radiation oncology. Protons have a distinct advantage in that they can deliver a concentration of energy to a specific depth in the body, potentially improving treatment efficacy and reducing side effects.

Other options pertain to functions that are unrelated to the primary purpose of a Linear Accelerator. For instance, creating cross-sectional images is associated with imaging techniques like CT scans. Similarly, capturing films of bone might refer to traditional X-ray imaging rather than therapeutic applications. Measuring scattering ability is more relevant to experimental physics and materials research rather than direct therapeutic use. Therefore, the correct answer reflects the main application of Linear Accelerators in modern cancer treatment protocols.