Proton therapy is an emerging radiation therapy technique to deliver highly-targeted doses with ionizing radiation beams to cancer patients with improved sparing of healthy surrounding tissues and reduced toxicity compared to conventional photon beam radiotherapy. While traditionally patients are irradiated in supine position, with the radiation beam being rotated around the patient to target the tumour volume from multiple angles, recent technological developments have made it possible to do the opposite. Instead of using bulky equipment to rotate the radiation beam around the patient, robotics has made it possible to rotate the patient in upright position relative to a stationary beam generated by compact equipment. This not only saves costs and space, but also improves system reliability and increases patient comfort. 

Image guidance during treatment is crucial to assure highly accurate dose delivery. The recent development of a vertical computed tomography (CT) device enables the acquisition of anatomical images at the treatment isocentre prior to irradiation and during each treatment fraction. This allows for adaptive therapy, taking into account anatomical variations that occur during the course of treatment. Since the targeting accuracy of proton therapy is more sensitive to anatomical variations than photon therapy, tumour shrinkage and/or motion as well as organ deformation during dose application must be accounted for. However, the lack of real-time image guidance is currently the dominant limiting factor in achieving a higher targeting accuracy for moving tumours with proton therapy. 

Magnetic resonance imaging (MRI) has the capability to provide unrivalled soft-tissue contrast images in real-time. However, the development of in-beam MRI for proton therapy has only recently started and not yet reached technical maturity to be introduced into the clinic. Recently, a unique, whole-body in-beam MRI device has been installed at HZDR/OncoRay in Dresden (Germany). By means of the rotating, open-bore magnet, this device offers the possibility to scan and irradiate patients in both recumbent and upright posture. Upright patient positioning in this device is challenging from a technical, ergonomical and workflow point-of-view. 

Objective 

The aim of this project is to optimize an upright patient positioning system (UPPS) to be used inside the in-beam MRI device with respect to both patient comfort and immobilization. An inclusive design of an MR-compatible UPPS for a future clinical upright MR-integrated proton therapy system should be developed. 

Tasks 

To assemble key anthropometric and mobility data for different patient subgroups. To consider relevant patient demographics for the highest patient inclusivity in the development of bespoke immobilization devices to be used for different patient postures in the upright position. To consider occupational health of the staff to achieve an ergonomic workflow with the UPPS. To study and verify the positional accuracy of said immobilization devices in the in-beam MRI device at HZDR/OncoRay.