Fast and compact proton radiography imaging system for proton radiotherapy

Transcription

1 Fast and compact proton radiography imaging system for proton radiotherapy Aleksandra K. Biegun ATTRACT NL Kick-off event, 9 th February 2017, Amsterdam, The Netherlands

2 Proton therapy work flow CT scan Knowledge of patient HU =1000 µ µ water µ water Translation 3D map of proton stopping powers (PSP) Treatment planning " $ # de dx % ' & Treatment verification Treatment ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun Fast and compact proton radiography imaging system for proton radiotherapy 2

3 Knowledge of the patient and its consequence CT scan HU =1000 µ µ water µ water Schneider approach Schneider et al, PMB 41 (1996) 111 o Conversion HU to proton stopping power is NOT unique o Systematic uncertainties of 3-4% or more require larger than neccessary irradiation safety margins around the tumor 3D map of proton stopping powers " $ # de dx % ' & Increased dose to healthy tissues ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun Fast and compact proton radiography imaging system for proton radiotherapy 3

4 Why proton radiography? ² Direct measurement of proton stopping powers (model free) ² High resolving power for proton beam (centerpiece of the pen visible) ² X-ray produces a clearer image of the spring, but density resolution for the centerpiece is not high high proton energy (180 MeV) Ruy et al, PMB53 (2008) 5461 low proton energy (40 MeV) X-rays Protons help determining energy losses in soft materials ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun Fast and compact proton radiography imaging system for proton radiotherapy 4

5 Current systems with tracking s Residual energy-range G. Poludniowski et al., Br J Radiol (2015) 88: Group Year (# of units) Residual Energy-Range Detector Rate (Hz) Imaging device PSI 2005 x-y Sci-Fi (4) Plastic scintillator telescope 1 M prad ² Trend towards Si tracking s (individual proton) Fast, BUT with high Z, high ρ more Multiple Coulomb Scattering à more blurred image ² Different approaches for energy/range s Too slow / too thin ² Count rate close to required Size / configuration not yet optimal LLU/ UCSC/NIU LLU/ UCSC/ CSUSB 2013 x-y SiSDs (4) CsI (Tl) 15 k pct 2014 x-y SiSDs (4) AQUA 2013 x-y GEMs (2) PRIMA I 2014 x-y SiSDs (4) PRIMA II 2014 x-y SiSDs (4) Plastic scintillator hybrid telescope Plastic scintillator telescope YAG:Ce calorimeter YAG:Ce calorimeter 2 M pct 1 M prad 10 k pct 1 M pct INFN 2014 x-y Sci-Fi (4) x-y Sci-Fi 1 M pct NIU/FNAL 2014 x-y Sci-Fi (4) Niigata University 2014 x-y SiDs (4) Plastic scintillator telescope NaI (Tl) calorimeter 2 M pct 5 k pct CMOS APS PRaVDA 2015 X-u-v SiSDs 1 M pct ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun Fast and compact proton radiography imaging telescope system for proton radiotherapy 5

6 Ideal system with tracking s Residual energy-range ü s Low Z and WET à minimum MCS in Fast à high count rate (> MHz), time resolution ~ns Spatial resolution à 50 µm Full proton track determination Modular and compact à 30x30 cm 2 ü Residual energy Good energy resolution of up to 1% (YAG:Ce, LaBr 3 ) Fast à high count rate (> MHz) ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun Fast and compact proton radiography imaging system for proton radiotherapy 6

7 Ideal system with tracking s ü Easy to mount on a gantry in proton therapy centers ü Scan time + reconstruction of up to few sec All to be clinically acceptable! Residual energy-range ü s Low Z and WET à minimum MCS in Fast à high count rate (> MHz), time resolution ~ns Spatial resolution à 50 µm Full proton track determination Modular and compact à 30x30 cm 2 ü Residual energy Good energy resolution of up to 1% (YAG:Ce, LaBr 3 ) Fast à high count rate (> MHz) ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun Fast and compact proton radiography imaging system for proton radiotherapy 7

8 Energy loss radiographs: ΔE = E beam -E residual (Geant4) ² All protons that passed through phantom and three s ΔE (MeV) ² Protons with maximum scattering angle θ < 5.2 mrad ΔE (MeV) Selecting protons traveling along straight lines improves the image quality A.K. Biegun et al., JINST 11 C12015 (2016) ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun Fast and compact proton radiography imaging system for proton radiotherapy 8

9 Proton CART (Exp 2015) Collaboration with J. Visser, M. van Beuzekom, E. Koffeman Improved part of detection system: KVI-CART, May 2015 Position: TPC based on Timepix3 - factor 100 faster data acquisition compared to GridPix used in experiment (May 14) imaged à 100x more data object Energy: BaF2 scintillator (patient) energy position tracking phanton Count rate ~20 khz increased by factor 100!! but still not high enough for clinical requirement ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun tracking Proton beam Fast and compact proton radiography imaging system for proton radiotherapy 9

10 Energy loss reconstruction: Sims vs. Exp 2015 ² Phantom partially covered by Timepix3-based TPCs (3.0 x 3.0 cm 2 ) ΔE (arb. unit) ² θ < 5.2 mrad ΔE (MeV) Lung Fat/Air/CTsw Preliminary PMMA Simulations and experimental results are comparable Master thesis: M. Dietze with J. Visser, M. van Beuzekom, E. Koffeman (Nikhef,June 2016) ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun Fast and compact proton radiography imaging system for proton radiotherapy 10

11 Summary Fast and compact detection system Good spatial, angular and energy resolutions Compatible with reconstruction algorithms An accurate proton stopping power map of the patient à Accurate treatment plan à Full benefit from proton radiotherapy ATTRACT NL Kick-off event, Amsterdam 9 February 2017 Aleksandra K. Biegun Fast and compact proton radiography imaging system for proton radiotherapy 11