Wider research context:
Low gain avalanche detectors (LGADs) are novel ultra-fast silicon detectors which allow the simultaneous measurement of the position and time-of-arrival of individual particles with excellent spatial (< 100 µm) and time precision (< 100 ps), so-called 4D-tracking. Employing this new detector technology for ion computed tomography (iCT), an imaging modality for the direct measurement of the relative stopping power distribution inside the patient, could help to overcome the limitations of current iCT prototype systems, especially the limited rate capability. This would not only help to make iCT clinically relevant for ion beam therapy and therefore improve the treatment planning quality, but it would also allow to explore completely new imaging concepts by incorporating time-of-flight (TOF) measurements into the imaging process, so-called 4D-tracking iCT.
Objectives:
The main goal of this study is to conduct the first experimental study of the innovative 4D-tracking iCT approach, aiming to show its feasibility in fulfilling all clinical requirements. For that purpose, two different scanner and imaging concepts will be explored , i.e. 4D-tracking iCT with a TOF calorimeter and the sandwich TOF-iCT approach. The latter is a novel, untested imaging concept, which, in contrast to any other iCT system, does not require a residual energy detector, thus making the system more compact, cost efficient and easier to integrate into the treatment room.
Methods:
The first 4D-tracking iCT scanner using an existing LGAD readout system developed at GSI will be built and tested. For both imaging modalities, a proof-of-concept measurement at the ion beam therapy centre MedAustron in Austria, by creating iCT scans of small inanimate objects to benchmark each design, is planned. New calibration methods for the sandwich TOF-iCT modality using TOF measurements through different homogeneous objects will be optimised and explored.
Level of originality:
It will be the first time that a 4D-tracking iCT system will be built and tested, including the experimental realisation of both of the investigated imaging modalities. Especially results for the sandwich TOF-iCT method are highly anticipated by the scientific community as no previous measurements of the TOF through different materials with such high time precision (<100 ps) have been conducted.
