Portal radiography in veterinary radiation oncology: options and considerations.

Portal radiography involves the acquisition of images to visualize radiation treatment field(s) using the radiation treatment source. The standard has been the use of film-based systems with improvements over the years in film-screen technology providing near diagnostic quality images. More recent advances have included the development of digital systems with such notable improvements including ability to window/level images to enhance viewing and readability, and significant shortening of the time required to acquire images.