What is the size of the flat-panel detector inside the table of a DR system?

The size of the flat-panel detector typically found in a digital radiography (DR) system is indeed 17 x 17 inches. This size is standard for many applications as it provides a balance between capturing large areas for imaging and maintaining adequate resolution and detail. A detector of this size allows for flexibility in imaging different body parts, including larger areas such as the abdomen or pelvis, while still being manageable for positioning and workflow within a clinical setting.

The use of a 17 x 17 inch detector enhances the capability to obtain high-quality images in a variety of clinical situations without the limitation of smaller detector sizes, which might require multiple exposures to cover an equivalent area. Therefore, this size is optimal for many imaging scenarios in the medical field, making it the correct choice for this question.