ABSTRACT
Beam's eye view radiographic imaging refers to the acquisition of planar X-ray projection images using the megavoltage linear accelerator treatment beam as the X-ray source and an X-ray imaging receptor to collect and display the image for the purpose of patient localization and treatment verification. The poorer contrast properties of the incident megavoltage (MV) beam and the reduced detection efficiency at high energies limits the image quality and requires higher doses to the patient for a useful anatomical image compared to a diagnostic radiography system. Image-guided radiation therapy requires the registration of an image acquired at treatment with a reference image. All modern radiotherapy treatment planning systems (RTPS) contain tools for generating and manipulating digitally reconstructed radiographs (DRRs). Some RTPS's include tools to define volumes of interest for the generation of DRRs that exclude parts of the anatomy that are not of interest or obscure features of interest.
