Call 18203/2016 per il finanziamento di 6 progetti per giovani ricercatori High performance 3D CadmiumZinc-Telluride spectro-imager for X and gamma-ray applications 3CaTS Nicoletta Protti, National Institute of Nuclear Physics INFN, Pavia Unit
Specific Objective: real-time 10B dose measurement in BNCT (Boron Neutron Capture Therapy) BNCT is an experimental form of binary radiotherapy based on the exothermic (Q = 2.79 MeV) nuclear reaction of the stable isotope 10B Lethal damages in cancer cells are produced if enough 10B is selectively loaded by the tumour (secondary particle ranges < 10μm)
General problem in BNCT dosimetry BNCT celllevel selectivity and biological effectiveness thermal neutron flux distribution at tumour site B microscopic distribution at irradiation time 10 dd(x,y,z) nb10(x,y,z) (x,y,z) dv Monte Carlo-based Treatment Planning Systems (TPS) validated through TEphantom measurements PET 10 irradiation B infusion blood samples and ICPS
in vivo BNCT dosimetry by single photon detection dd(x,y,z) nb10(x,y,z) (x,y,z) dv di (x,y,z) ray 478 kev photon detector
3CaTS goal To develop and build an innovative fully functional highly segmented prototype of a CdZnTe (CZT) solid state photon detector to prove and evaluate its perfromance as room temperature spectrometer with 3D spatial resolution capabilities suitable for different spectroscopic imaging applications in the range from few tens of kev up to 1 MeV medical imaging fine spectroscopy for fundamental physics hard-x and soft- rays astronomy
in vivo BNCT dosimetry by single photon detection detector neutron (25 mev) 7 10 B Li REQUIREMENTS 478 kev particle BNCT group in Pavia currently involved in small animal (rats, mice) tumour models irradiation at the thermal neutron facility of Pavia University TRIGA Mark II reactor detector high spatial resolution (~ 1mm) good detection efficiency @ 478 kev compact and portable imaging system
Available Nuclear Medicine detectors LSO spatial resolution few mm room for further development: small FOV imagers (myocardial perfusion imaging, scintymammography), MRI-coupling, preclinical studies and molecular imaging
Compound semiconductor detectors By selecting the physical properties (band gap, atomic number, density, etc...) through the material growth process it is possible to tailor and customize the compound semiconductor to the specific application of interest. Presently, Cadmium-Zinc-Telluride (CZT) is receiving increasing attention for the development of X and gamma ray detectors operating in the energy range from few tents of kev up to 1 MeV
Compound semiconductor detectors By selecting the physical properties (band gap, atomic number, density, etc...) through the material growth process it is possible to tailor and customize the compound semiconductor to the specific application of interest. Presently, Cadmium-Zinc-Telluride (CZT) is receiving increasing attention for the development of X and gamma ray detectors operating in the energy range from few tents of kev up to 1 MeV high Z high detection efficiency, favored photoelectric effect over Compton one wide band gap leakage current < na, room temperature operation
Compound semiconductor detectors By selecting the physical properties (band gap, atomic number, density, etc...) through the material growth process it is possible to tailor and customize the compound semiconductor to the specific application of interest. Presently, Cadmium-Zinc-Telluride (CZT) is receiving increasing attention for the development of X and gamma ray detectors operating in the energy range from few tents of kev up to 1 MeV high Z high detection efficiency, favored photoelectric effect over Compton one wide band gap leakage current < na, room temperature operation charge carriers trapping, 2-3 o.m. difference in between electrons and holes degradation of energy resolution and operative limits at high count rates
Compound semiconductor detectors Main drawback of CZT as radiation detection material: (1) challenging growth technology to deliver big (1-2 inches diameter) detector-grade crystals and (2) low carrier mobility (in comparison with traditional Si and Ge semiconductor detectors) (1) Boron oxide encapsulated vertical Bridgman technique (state of art) to prevent crystal-crucible contact Zone 3 TC3 TC2 Zone 2 TC1 Zone 1 detector-grade large single grain crystals up to 3 inches very low dislocation density (< 104 cm-2; minimum value of 1.5 103 cm-2)
3CaTS proposed detector 3D-CZT sensor: 20x20x5 mm3, Limited number of read-out channels (30) but still high segmentation. planar transversal field (PTF), orthogonal strip electrodes (20 + 10), contact pitches of 2 mm (cathode) and 1 mm (anode, 1 central read-out strip + 4 drift strips/side) Bottom face face(*) (*) Bottom Top face face Top -rays (*) drift strips not reported -rays PPF PTF
3CaTS proposed detector 3D-CZT sensor: 20x20x5 mm3, planar transversal field (PTF), orthogonal strip electrodes (20 + 10), contact pitches of 2 mm (cathode) and 1 mm (anode, 1 central read-out strip + 4 drift Bottom face face(*) (*) Bottom Top face face Top -rays (*) drift strips not reported -rays photon irradiation strips/side)
3D position sensing CZT spectrometers CZT spectrometer with spatial resolution in three dimensions (3D CZT) are a new frontier. The advantage offered by 3D reconstruction of both the photon interaction position and the single energy deposition are fundamental for applications requiring high detection efficiency even in the Compton regime (> 100 kev) and a uniform and fine spectroscopic response throughout the sensitive volume (correction for signal variations due to charge trapping and material non-uniformity).
Imagin reconstruction software Proposed energy range: few tens kev up to 1 MeV, with special emphasis around 500 kev Compton interaction probability in CZT crystal 4 times that of photoelectric effect Development of a software for image reconstruction able to take advantage of the Compton events inside the 3D spectrometric sensor: - co-registration of interaction position and deposited energy per hit => - imaging reconstructed by analysing the distribution of the intersections of the incidence cones of Compton kinematic and through the use of statistical methods (e.g. maximum likelyhood) and the results of Monte Carlo simulations (GEANT4) Through this tool we could drastically improve the detection efficiency and the wide angle response of the detector at high energy, allowing the implementation of reliable and effective reduction of noise.
3CaTS proposed detector 3D-CZT sensor: 20x20x5 mm3, planar transversal field (PTF), orthogonal strip electrodes (20 + 10), The 3D spatial detection capability requires fast electronics able to perform pulse detection and trigger time tagging with high resolution (< 1ns), allowing time coincidence measurements in short time coincidence windows. contact pitches of 2 mm (cathode) and 1 mm (anode, 1 central read-out strip + 4 drift strips/side) Bottom face face(*) (*) Bottom Top face face Top -rays (*) drift strips not reported -rays Digital approach: detector output signal from CSP directly fed into fast digitizers and processed by digital algorithms Other advantages: - customable filters and procedures - stability and reproducibility - off-line and real-time analysis - PSA to minimize incomplete charge collection distortions, pile-up, recovery signal through DOI information and charge sharing - reduction and control of dead time effects
Required expertise for positive realization of 3CaTS project imaging in Compton regime BNCT and neutron facility crystal growth fast and customable electronics
Required expertise for positive realization of 3CaTS project imaging in Compton regime na g lo o B Pav ia BNCT and neutron facility rm a P a Palermo crystal growth fast and customable electronics
Required expertise for positive realization of 3CaTS Unit 1. project BNCT-related studies at reactor-based neutron facility; research topics: 10B concentration measurment techniques ex-vivo; neutron measurements and (n+ )-dosimetry; Monte Carlo MCNP simulations BNCT and neutron facility CZT procurement and realization of prototypes imaging in Compton regime na g lo o B Pav ia rm a P Unit 3. study, design and realization of semiconductor detectors (CdTe, CZT) and related front-end/readout electronics for hard X ad soft spectroscopy and imaging for astrophysics missions a Palermo crystal growth fast and customable electronics Unit 2. Research topics: development of semiconductor radiation detectors (CdTe, CZT) and digital electronics (digital pulse processing systems) for X and -rays detection
3CaTS workpackages, milestones and timetable Year 1 WP Tasks 1 Detector system design and construction (U1+U2+U3) 2 Digital multichannel electronics (U2) 3 Sensor Characterization and Signal/Imaging reconstruction (U1+U3) 4 BNCT application (U1) 5 Astrophysical application (U3) Milestones Q1 Q2 Q3 Year 2 Q4 i) construction of 2 fully functional CZT prototypes, with complete bonding and interface to digital multichannel electronic; ii) detectors and electronics characterization and test; Iii) development and preliminary testing of fully functional image reconstruction software. Q1 Q2 Q3 Q4 completion of comprehensive tests and characterizations of at least 1 prototype: i) for BNCT-SPECT; ii) for hard X and soft astrophysics
Single tasks assignement Unit Member 1 BNCT and medical applications N.Protti (PI), >80% 2 electronics Individual tasks Project management, design of whole detection system, planning of performance tests, in particular for BNCT-SPECT S.Fatemi, 100% S.Altieri, 30% A.De Bari, 40% (2018) BNCT-SPECT, MCNP simulation, test with gamma sources of reference for PET and SPECT, test at thermal neutron facility of Pavia LENA laboratory, image reconstruction software test in BNCT frame; evaluation of detector performance for PGNA-analysis; realization of testing campaign in fundamental physics application, with particular emphasis to detector performance comparison with HPGe L.Abbene (LR), 50% Assistance in project management as local responsible of Unit 2 and in whole detection system design with special emphasis for digital electronics F.Principato, 20% 3 N.Auricchio (LR), 35% image reconstruction and E.Caroli, 20% astrophysical J.Stephen, 20% applications A.Basili, 20% S.Silvestri, 20% Developing, testing and characterization of digital electronics Assistance in project management as local responsible of Unit 3 and in design of whole detection system with special emphasis to astrophysical applications, in particular as focal plane detector of a broad band Laue lens as well as scattering polarimeter for hard X and soft gamma rays Development of software for Compton imaging and its test in astrophysical frame; implementation of the detector system in the LARIX Laue facility and realization of performance test with Laue crystals; realization of polarization measurements at ERSF (Grenoble, France)
3CaTS costs: INFN contribution Costs (k ) Year 1 Year 2 Total Instrumentation 73 17 90 Consumables 0 14.5 14.5 Services 0 23 23 Travels 2 11 13 TOTAL 75 65.5 140.5 Motivation Year 1 i) 2 prototype 3D-CZT detectors and digital electronics Year 2 i) mechanical supports @ LARIX facility, liquid cold plate, X and ray collimator ii) radioactive sources for BNCT-SPECT purpose (and possibly astrophysics) Year 2 i) 6Li-enriched Li2CO3 powder for thermal neutron shielding ii) consumables @ LARIX facility Iii) general electronics components Year 2 i) irradiation time at Pavia TRIGA Mark II reactor ii) experimental time @ LARIX facility Project advancement meetings, detector measurement campains at Pavia reactor, LARIX and eventually Grenoble ESR facilities
3CaTS costs: cofinancy from non-infn Units Unit k in-kind 2 University of Palermo 42 Detector and electronics laboratory equipped with instrumentation for characterization of the digial electronics 3 INAF Bologna 42 Physics and electronics laboratory equipped with instrumentation, micrometric positioning systems and multi-parameters data acquisition systems; imaging reconstruction software. TOTAL 84 due2lab NOT directly involved in project research, merely fornitore of the 2 3D-CZT prototypes following U1+U2+U3 s required system design and lay-out.
3-CaTS (3D Cadmium-Zinc-Tellurium Spectro-imager for X and gamma-ray applications) project Main goal of the project: o highly segmented CZT semiconductor spectrometer with 3D spatial resolution capabilities working at RT o energy range from few tens of kev up to 700 kev for multi-purpose applications o high efficiency, fine spectroscopy and imaging, limiting the complexity of detector design and realization Expected characteristics and performance: o intrinsic geometrical space resolution of 1x5x2 mm 3 improvable by reconstruction methods up to 0.2x0.3 mm2 in the plane directly exposed to the photon flux ( x y) and 0.6 mm in depth ( z) o energy resolution: < 3% at 500 kev without correction, improvable to < 1% after corrections o detection efficiency at 478 kev: 13% for photoelectrons, 52% for Compton scattered events o operating energy range: 20-700 kev
Backup slides
Single tasks assignement Unit Member 1 N.Protti (PI), >80% Project management, design of whole detection system, planning of performance tests, in particular for BNCTSPECT (MCNP simulation), and integration of the subsystems, test of prototypes with gamma sources of reference for PET and SPECT, test of protoypes at the thermal neutron facility of LENA laboratory in Pavia, supervision of image reconstruction software and its test in BNCT frame, evaluation of detector performance for prompt gamma neutron activation analysis S.Fatemi, 100% S.Altieri, 30% A.De Bari, 40% (2018) Detection system design for BNCT-SPECT (MCNP simulation), test of prototypes with gamma sources of reference for PET and SPECT, test of protoypes at the thermal neutron facility of LENA laboratory in Pavia, development of image reconstruction software and its test in BNCT frame Assistance in project manageemnt and in design of whole detection system with special emphasis for BNCT application, supervision of test of prototypes at thermal neutron facility of LENA laboratory, evaluation of detector performance for PGNA-analysis Supervision of test of prototypes with gamma sources of reference for PET and SPECT, realization of testing campaign in fundamental physics application, with particular emphasis to detector performance comparison with HPGe L.Abbene (LR), 50% Assistance in project management as local responsible of Unit 2 and in design of whole detection system with special emphasis in digital electronics (design of front-end preamplifiers and buffers; design of digitizers; design and realization of mounting and front end boards; design and development of the digital firmware for multichannel read-out; development of the software for correction and compensation of signals 2 F.Principato, 20% 3 N.Auricchio (LR), 35% E.Caroli, 20% J.Stephen, 20% A.Basili, 20% S.Silvestri, 20% Individual tasks Assistance in developing, testing and characterization of digital electronics Assistance in project management as local responsible of Unit 3 and in design of whole detection system with special emphasis to astrophysical applications, definition of performance tests of prototypes as focal plane detector of a broad band Laue lens as well as scattering polarimeter for hard X and soft gamma rays, realization of polarization measurements at ERSF (Grenoble, France) Development of software for Compton imaging and its test in astrophysical frame Implementation of the detector system in the LARIX Laue facility and realization of performance test with Laue crystals
Compound semiconductor detectors Main drawback of CZT as radiation detection material: (1) challenging growth technology to deliver big (1-2 inches diameter) detector grade crystals and (2) low carrier mobility (in comparison with traditional Si and Ge semiconductor detectors) (2) low carrier mobility Irradiation geometry Electronic methods Electrode design
3-CaTS proposed detector 3D-CZT single unit: 20x20x5 mm3, planar transversal field (PTF), orthogonal strip electrodes (20 + 10), contact pitches of 2 mm (cathode) and 1 mm (anode, 1 central read-out strip + 4 drift strips/side) Bottom face face(*) (*) Bottom Top face face Top -rays (*) drift strips not reported -rays The anode strip signal is independent of the photon interaction position The induced signal on cathode electrodes is dependent on the depth of interaction. By combining the effect of the hole trapping with the single polarity charge sensing ability, we can obtain information on the radiation interaction depth through the Ratio R between the collected charges Qcathode and Qstrip. The depth information (R) can be used to correct the anode strip signal fluctuation caused by the electron trapping and the non ideal weighting potential effect
3CaTS proposed detector
Main radiation components @ BNCT accelerator-based facility single photon detector sampling positions treatment room scattered radiations: epithermal and fast n + incident n beam + contamination primary beam scattered n +, n-induced photons: 1 H(n, )2H 10 B(n, )7Li*