Comparison of cone beam and fan beam (tomotherapy) adaptive radiotherapy: physical and clinical developments and evaluation of new approaches of intensity modulated raditotherapy

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Tomotherapy is a new form of radiation delivery. Although still in its clinical infancy, preliminary results are encouraging. The potential of a clinical superior radiation delivery device is to be compared with the present day linear accelerator radiation delivery and the clinical treatment possibilities promised by proton and heavy ion irradiation. A ranking of treatment modalities depending on the clinical demands should be provided. Tomotherapy combines computed tomography with a radiation delivery system. The unit integrates treatment planning, patient positioning, and treatment delivery into one system. It has the potential to significantly improve patient care by virtue of its increased precision in treatment delivery, which may result in reduced toxicity and dose escalation. While clinicians are optimistic about these potential clinical benefits, this has not yet been established. Further, changes in practice resulting from the introduction of tomotherapy in the clinic would likely impact the current organizational structure. For example, increased precision may allow a reduction in the number of fractions, the impact of image guided positioning of the patient may lead to a rising number of virtual simulations replacing stereotatic treatments.The aim of this proposal is to evaluate the future role of tomotherapy in radiation oncology. Tomotherapy especially delivered in its helical form represents a new way to deliver radiation therapy to arbitrarily shaped target volumes. We want to show if potential advantages of tomotherapy such as higher dose conformality to the target volume and better sparing of normal structures at faster treatment time hold true under clinical conditions. The possibility of online imaging allows for correction of daily setup uncertainties and even may allow to take into account intrafractional movement. The tomotherapy requires a whole new treatment unit which includes the treatment planning and delivery. Currently different approaches of treatment delivery with conventional linearaccelerators equipped with multileafcollimators are being developed. Therefore a systematic evaluation of the tomotherapy approach seems to be justified. We propose to compare one set of parameters which includes medical physics characteristics, treatment planning parameters, radiobiological experiments, socioeconomical considerations and the safety of application and also clinical results of the tomotherapy approach to that of IMRT with linacs and ion beams in the hands of experienced users.The clinical studies will focus on breast cancer, prostate cancer, lung cancer including mesothelioma, upper gastrointestinal tract tumors, prostate cancer and CNS tumors. Patients will be included in phase I/II and in randomized phase II studies. The aim is to identify the characteristics of patients who will benefit from one or the other form of radiation therapy and to predict the best modality for these patients. Finally the number of tomotherapy units which would be eventually necessary should be estimated.