ABSTRACT
This chapter includes photon-beam delivery methods in which anatomic motion is implicit and covered in margins, as well as delivery methods in which anatomic motion is explicitly accounted for, that is, gating and real-time adaptive radiotherapy on conventional, robotic, and gimballed linear accelerators. The chapter excludes four-dimensional (4D) dosimetry approaches for proton and carbon ion beams, and abdominal compression and breath-hold techniques that reduce motion. 4D dosimetry is needed because patient motion creates one of the largest uncertainties in the treatment chain, along with contouring uncertainties. 4D dosimetry is commonly performed for both experimental and clinical reasons using volumetric detectors moved by programmable phantoms. Anthropomorphic programmable phantoms, which are heterogeneous, are often used for treatments such as lung where there are large differences in tissue density through which the radiation travels. The data required for 4D dosimetry include treatment plans and motion traces. An increasing number of 4D dosimetry studies are performed for real-time adaptive radiotherapy treatment techniques.
