HELIOS – Developing a HELium Imaging Oncology Scanner for Range Guided Radiotherapy (RGRT) for Non-Small Cell Lung Carcinoma (NSCLC)

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The goal of radiotherapy (RT) for lung cancer is to deliver radiation dose to the tumor while minimizing exposure of sensitive organs at risk (OARs) such as lung, heart and esophagus. Treatment has, therefore, always been a trade-off between tumor control and organ toxicity. However, in the lung many times the tumors are moving due to patient breathing. Changes in patient anatomy due to motion can occur at time scales ranging from seconds (intrafractional) to days or even several weeks (interfractional). The benefit of carbon ion therapy is challenged by both interfractional anatomical changes and intrafractional motion. In the treatment of moving lung tumors, the benefit of particle therapy is significantly reduced due to the impact of tumor motion and range uncertainties increasing the radiation dose to the OARs. We propose to develop an Helium Imaging Oncology Scanner (HELIOS) to facilitate range guided radiotherapy (RGRT) to reduce toxicity in carbon ion therapy of non-small cell lung carcinoma (NSCLC), by in-vivo monitoring of the delivered dose to a moving tumor. The RGRT approach is based on a carbon beam with mixed-in helium ions, resulting in helium ions exiting the patient due to their longer range at same energy per nucleon. The exiting helium ions will allow for in-vivo and real-time monitoring of the carbon Bragg peak within the patient with 2mm accuracy, reducing the amount of healthy tissue that is irradiated. This will reduce patient toxicity and allow for improved tumor control.To develop HELIOS, we apply for funding for detector components and research personnel to implement hardware & software for the use of HELIOS in a clinical research environment. A more experienced postdoctoral researcher will tackle the commissioning and validation of the HELIOS prototype at the Heidelberg Ion Therapy Center (HIT) through construction of an appropriate lung phantom and corresponding measurements. Here, the project can rely on substantial preliminary work investigating helium/carbon mixing. A PhD student will concurrently develop the algorithms necessary for RGRT treatment planning and image processing for HELIOS. This includes Monte Carlo simulation of dose and range radiographs on 4D imaging data as well as uncertainty estimates. The PhD student can rely on the open-source research treatment planning toolkit matRad developed at DKFZ and validated at HIT, which serves as powerful backbone for the software development and further use in research.The final phase of the project will bring together both HELIOS hardware and software to pave the way for upcoming basic and clinical research projects and application scenarios. Focus will lie on correlating further online in-room data, in particular surface images, to the dose planning simulations and range measurements to develop research protocols and clinical decision criteria for RGRT with HELIOS.