Organ motion is a substantial concern in the treatment of thoracic tumours using radiotherapy. A number of technologies have evolved in order to address this concern in both the fields of CT imaging and radiation delivery. This review paper investigates the technologies which have been developed for the delivery of radiotherapy as well as the accuracy and workload implications of their use. Treatment techniques investigated include: breath hold, breath gating, robotic compensation and MLC manipulation. Each technique has its own advantages and drawbacks in regards to accuracy, treatment time, linac alterations and workload. Further, some treatment techniques have specific requirements for what kind of CT scans needs to be used in the planning process. This, along with the aforementioned considerations, could influence the decision as to implement some of these treatment techniques in the clinic.

Minimal invasive tumor therapies are getting ever more sophisticated with novel treatment approaches and new devices allowing for improved targeting precision. Applying these effectively requires precise localization of the structures of interest. Vital processes, such as respiration and heartbeat, induce organ motion, which cannot be neglected during therapy. This review focuses on 4D organ models to compensate for respiratory motion during therapy. An overview is given on the effects of motion on the therapeutical outcome, methods required to capture and quantify respiratory motion, range of reported tumor motion, types of surrogates used when tumors are not directly observable, and methods for temporal prediction of surrogate motion. Organ motion models, which predict the location of structures of interest from surrogates measured during therapy, are discussed in detail.

Organ motion is a substantial concern in the treatment of thoracic tumours using radiotherapy. A number of technologies have evolved in order to address this both during computed tomography (CT) imaging and radiation delivery. This review paper investigates the various technologies which have been developed in the field of CT scanning as well as their accuracy, cost and the implications of their clinical implementation. The scanning modalities covered include: slow CT, breath hold CT, gated CT and retrospectively correlated CT (4DCT). It was found that there are advantages and drawbacks to each of the mentioned techniques relating to patient dose, scan time, extra equipment and workload. Also some scanning techniques are only compatible with certain treatment modalities which would further influence the decision as to which technologies to implement.