A cassette-less system in radiography is known as?

A cassette-less system in radiography is referred to as digital radiography. This technology allows for images to be captured directly and instantly on digital sensors without the need for traditional film or cassettes.

In digital radiography, the image acquisition process is streamlined and often involves a flat-panel detector or similar technology that converts x-ray energy into digital images, which can be viewed immediately on a computer screen. This leads to quicker processing times, enhanced image quality, and easier storage and retrieval of images compared to the older film-based methods.

The other options mentioned, such as analog radiography, film-based systems, and conventional radiography, all involve the use of physical film or cassettes to capture images, which is a defining characteristic not found in digital radiography. Thus, the distinction of being cassette-less is what clearly identifies digital radiography as the correct answer.