Particle therapy is an established method to treat deep-seated tumours using accelerator-produced ion beams. For treatment planning, the precise knowledge of the stopping power (SP) within the patient is vital. Currently, SP values are extrapolated from X-ray CT, thus introducing conversion errors, eventually leading to uncertainties in the applied dose distribution. Using a proton computed tomography (pCT) system for direct measurement of the SP has the potential to increase the accuracy of treatment planning.
A pCT demonstrator, consisting of double-sided silicon strip detectors (DSSD) as tracker and an upgraded version of the TERA range telescope comprised of plastic scintillator slabs coupled to silicon photomultipliers (SiPM) was developed. This system was used to image a 3D tomogram of an aluminium stair phantom at the accelerator facility MedAustron, Austria.
For image reconstruction, the GPU-based open source software framework TIGRE was used. Imaging results as well as technical and physical limitations of this pCT demonstrator will be discussed. Finally, a novel ion computed tomography (iCT) system based on 4D tracking detectors for particle path estimation as well as time-of-flight residual energy measurement will be proposed and first design study results for this iCT system will be presented.