The Bergen proton CT project Helge Pettersen Haukeland

The Bergen proton CT project Helge Pettersen, Haukeland University Hospital

3 -slide introduction Proton Computed Tomography if Pierluigi did bad

BERGEN PCT - HELGE PETTERSEN X-ray CT X-ray tube X-ray detector September 2019 PAGE 3

BERGEN PCT - HELGE PETTERSEN Proton CT High energy proton beam Energy detector Position detectors September 2019 PAGE 4 Position detectors

BERGEN PCT - HELGE PETTERSEN The energy detector Range telescope Scintillator September 2019 PAGE 5

Proton CT with a Digital Tracking Calorimeter First proof-of-concept detector

BERGEN PCT - HELGE PETTERSEN p. CT – Digital Tracking Calorimeter Beam Patient Assume proton vector & position September 2019 7 Measure multiple protons’ vector, position & track protons to find range

Beam tests in. BERGEN CERN + Groningen, NL (2014) PCT - HELGE PETTERSEN September 2019 PAGE 8

Protons hitting the pixel detectors Pixel Position Y [Pixel number] PHYS 212 - HELGE PETTERSEN April 2019 9 Pixel Position X [Pixel number]

Analysis workflow 10 PCT - HELGE PETTERSEN

BERGEN PCT - HELGE PETTERSEN Proof-of-concept: ALICE-Fo. Cal • From 2013: Analysis + beamtests with the ALICE-Fo. Cal detector for p. CT • Expectedly poor resolution • Track reconstruction possible at high rates – ~1 million/s across 16 cm 2 @ 2 k. Hz readout September 2019 PAGE 11

Proton CT with a Digital Tracking Calorimeter Second prototype

BERGEN PCT - HELGE PETTERSEN Alice Pixel Detector (ALPIDE) 4 3 n i E D I P L A n o e r o M September 2019 ! s e t u n i m 14 http: //bora. uib. no/handle/1956/16041: Design of High-Speed Digital Readout System for Use in Proton Computed Tomography

BERGEN PCT - HELGE PETTERSEN Monte Carlo simulations • A very important tool in detector development – Define geometry, materials, beam, readout… – Simulation of how the particles interact and how energy is deposited September 2019 PAGE 15

BERGEN PCT - HELGE PETTERSEN GATE • Geant 4 -based MC framework • Macro-based, simple to automate, e. g. to test iterative designs: September 2019 PAGE 16

Charge diffusion from proton tracks

Protons hitting the pixel detectors Pixel Position Y [Pixel number] PHYS 212 - HELGE PETTERSEN April 2019 18 Pixel Position X [Pixel number]

BERGEN PCT - HELGE PETTERSEN Charge diffusion in pixels September 2019 19 Pettersen, H. E. S. , 2018. Ph. D thesis

BERGEN PCT - HELGE PETTERSEN Heidelberg beam test: 2018 • September 2019 PAGE 20 Grimstad, S. , 2019. MSc: Simulation and analysis of clustering for proton CT Tambave, G. et al. , 2019. Nucl Instr And Meth in Phys Res A; 162626

BERGEN PCT - HELGE PETTERSEN Tambave, G. et al. , 2019. Nucl Instr And Meth in Phys Res A; 162626 September 2019 PAGE 21

UNIVERSITY OF BERGEN // HAUKELAND UNIVERSITY HOSPITAL Compare this to MIMOSA (Po. C) 22 Pettersen, H. E. S. , 2018. Ph. D thesis

BERGEN PCT - HELGE PETTERSEN MC modeling of Cluster Sizes • September 2019 PAGE 23

BERGEN PCT - HELGE PETTERSEN Pettersen, H. E. S. et al. , 2019. Physica Medica 63, 87– 97. September 2019 PAGE 24

BERGEN PCT - HELGE PETTERSEN Accuracy of cluster reconstruction September 2019 PAGE 25 Grimstad, S. , 2019. MSc: Simulation and analysis of clustering for proton CT

Track reconstruction

BERGEN PCT - HELGE PETTERSEN Proton track reconstruction • With a DTC-type detector: – Possible to reconstruct many protons in a single readout – All proton hits throughout the detector must be «de-spaghetti-fied» into tracks September 2019 PAGE 27

BERGEN PCT - HELGE PETTERSEN Tracking algorithm • September 2019 Pettersen, H. E. S. et al. , 2019. EPJ Wo. C (in press).

BERGEN PCT - HELGE PETTERSEN Stuff we’ve tried • September 2019 PAGE 29

BERGEN PCT - HELGE PETTERSEN Good track Incomplete track Unfiltered secondary Two tracks confused Unused cluster September 2019 PAGE 30 Garcia-Santos, A. , 2019. Utrecht University, Delft. MSc: Optimization of the Track Reconstruction Algorithm in a Pixel Based Range Telescope for Proton Computed Tomography

BERGEN PCT - HELGE PETTERSEN Pettersen, H. E. S. et al. , 2019. EPJ Wo. C (in press). September 2019 PAGE 31

BERGEN PCT - HELGE PETTERSEN Pettersen, H. E. S. et al. , 2019. Physica Medica 63, 87– 97. Aluminum absorber thickness (final = 3. 5 mm) September 2019 PAGE 32

BERGEN PCT - HELGE PETTERSEN What are the degrading effects? Pettersen, H. E. S. et al. , 2019. EPJ Wo. C (in press). September 2019 PAGE 33

BERGEN PCT - HELGE PETTERSEN Track filtering • September 2019 PAGE 34 Pettersen, H. E. S. et al. , 2019. Physica Medica 63, 87– 97.

BERGEN PCT - HELGE PETTERSEN Pettersen, H. E. S. , 2018. Ph. D thesis September 2019 PAGE 35

BERGEN PCT - HELGE PETTERSEN What happens to bad tracks? • September 2019 PAGE 36

Range calculation

BERGEN PCT - HELGE PETTERSEN Finding the proton range Pettersen, H. E. S. , 2018. Ph. D thesis September 2019 PAGE 38

BERGEN PCT - HELGE PETTERSEN • September 2019 PAGE 39 Pettersen, H. E. S. et al. , 2018. Radiat. Phys. Chem. 144, 295– 297.

BERGEN PCT - HELGE PETTERSEN Range resolution from individual tracks Pettersen, H. E. S. et al. , 2019. Physica Medica 63, 87– 97. September 2019 40

BERGEN PCT - HELGE PETTERSEN Range accuracy and precision Range straggling September 2019 PAGE 41 Range straggling + detector uncertainty

BERGEN PCT - HELGE PETTERSEN Range distribution per beam energy Pettersen, H. E. S. et al. , 2019. Physica Medica 63, 87– 97. September 2019 42

BERGEN PCT - HELGE PETTERSEN Pettersen, H. E. S. et al. , 2019. Physica Medica 63, 87– 97. September 2019 PAGE 43

BERGEN PCT - HELGE PETTERSEN September 2019 PAGE 44 Pettersen, H. E. S. et al. , 2019. Physica Medica 63, 87– 97.

BERGEN PCT - HELGE PETTERSEN Design choice: 3. 5 mm Pettersen, H. E. S. et al. , 2019. Physica Medica 63, 87– 97. September 2019 PAGE 45

BERGEN PCT - HELGE PETTERSEN Number of layers needed Pettersen, H. E. S. et al. , 2019. Physica Medica 63, 87– 97. September 2019 PAGE 46

What about images?

The Most Likely Path scheme The Most Likely Path (MLP) of the proton through the object • A model fit to the entry and exit angle/position ! y • Use the curves for image reconstruction a n o re o M 48 n o P L M d s r u h T Li, T. , et al. , Reconstruction for proton computed tomography by tracing proton trajectories: a Monte Carlo study. Med Phys, 2006. 33(3): p. 699 -706

BERGEN PCT - HELGE PETTERSEN How to find the entrance position? ! y a d i Fr n o Measure before Use middle value g Estimate from front n i g position (not too bad eh!) the patient… of pencila beam m i d e MC tracks d i s e l Estimated g n i s tracks n o e r o M September 2019 PAGE 49 Krah N et al. (2018) PMB 63 (13) Also Pettersen HES, Volz L et al. Rejected by Phys Med Biol

BERGEN PCT - HELGE PETTERSEN References • • • September 2019 Garcia-Santos, A. (2019). MSc: Optimization of the Track Reconstruction Algorithm in a Pixel Based Range Telescope for Proton Computed Tomography. Utrecht University. Grimstad, S. (2019). MSc: Simulation and analysis of clustering for proton CT. Pettersen, H. E. S. (2018). Ph. D: A Digital Tracking Calorimeter for Proton Computed Tomography. University of Bergen. Pettersen, H. E. S. , Alme, J. , Biegun, A. , van den Brink, A. , Chaar, M. , Fehlker, D. , Meric, I. , Odland, O. H. , Peitzmann, T. , Rocco, E. , et al. (2017). Proton Tracking in a high-granularity Digital Tracking Calorimeter for proton CT purposes. Nucl. Instr. and Meth. in Phys. Res. A 860, 51– 61. Pettersen, H. E. S. , Chaar, M. , Meric, I. , Odland, O. H. , Sølie, J. R. , and Röhrich, D. (2018). Accuracy of parameterized proton range models; a comparison. Radiat. Phys. Chem. 144, 295– 297. Pettersen, H. E. S. , Alme, J. , Barnaföldi, G. G. , Barthel, R. , van den Brink, A. , Chaar, M. , Eikeland, V. , García-Santos, A. , Genov, G. , Grimstad, S. , et al. (2019 a). Design optimization of a pixel-based range telescope for proton computed tomography. Physica Medica 63, 87– 97. Pettersen, H. E. S. , Meric, I. , Odland, O. H. , Shafiee, H. , Sølie, J. R. , and Röhrich, D. (2019 b). Proton Tracking Algorithm in a Pixel-Based Range Telescope for Proton Computed Tomography. EPJ Web of Conferences In press. Pettersen, H. E. S. , Volz, L. , Sølie, J. , Rohrich, D. , and Seco, J. A Linear Projection Model to Estimate a Proton’s Position in a Pencil Beam For Single Sided List Mode Proton Imaging. Rejected PMB Tambave, G. , Odland, Odd Harlad, Pettersen, H. E. S. , Alme, J. , Genov, G. , Grøttvik, O. S. , Samnøy, A. T. , Röhrich, D. , Ullaland, K. , Ur Rehman, A. , et al. (2019). Characterization of Monolithic CMOS Pixel Sensor Chip with Ion Beams for Application in proton Computed Tomography. NIMA. Krah, N. , Khellaf, F. , Rit, S. , and Rinaldi, I. (2018). A comprehensive theoretical comparison of proton imaging set-ups in terms of spatial resolution. Physics in Medicine and Biology 63. PAGE 50

BERGEN PCT - HELGE PETTERSEN Thanks for your attention September 2019 51