High-Speed Data Acquisition Electronics for a PEM Scanner The ClearPEM Project Pedro Lousã (on behalf of the ClearPEM Consortium) 16th IEEE NPSS Real Time Conference 2009 Beijing May 12th, 2009

Breast Cancer Breast Cancer Mammography Most common type of cancer among women Second deadliest cancer One out of 9 women develop a form of breast cancer throughout her life Mammography Advantages Low cost Good sensivity/specificity Disadvantages Based in structural tissue changes Less reliable in dense breasts High false-positive rates 2

P.E.T. (Positron Emission Tomography) Based on the decay of a positron emitting radionuclide (tracer) 18F-FDG most commonly used radiotracer Based on histological and metabolical changes of the tissue PET vs. Mammography Advantages Not dependent on tissue density Very good sensivity Disadvantages More expensive Low sensivity for small lesions (WB-PET) 3

The ClearPEM Project Goal Framework Status High performance scanner, to approach the limits allowed by tracer physiology Framework Project developed in the framework of the Crystal Clear Collaboration, CERN Funded by the Portuguese Innovation Agency (AdI) 4.5 M€ investiment 6 years development Status IP licensend to PETsys, SA Scanner ready for clinical trials 4

The ClearPEM Project Requirements High counting sensitivity Detector capable of image resolution of 1 mm Detector capable to sustain a large flux of single photons (up to 10 MHz) On-line coincidence trigger with few ns resolution No data acquisition dead-time (up to 1 M coincidence events/s) Measurement of individual hits of Compton events in the detector Movable and compact dual-head detector plates with large active area No parallax effect 5

Fluorine-18 Fluordeoxyglucose (FDG) Concept Radiotracer 18F-FDG - Fluordeoxyglucose Scintillating Crystals LYSO:Ce Avalanche Photodiodes (APD) Hamamatsu S8550 Electronic Detector Custom developed ASIC Fluorine-18 Fluordeoxyglucose (FDG) 6

System Architecture FrontEnd Subsystem DAE Subsystem 7

Detector Technology Crystals APDs Detector Plates Material: LYSO:Ce Density: 7.4g.cm-3 Emission Peak: 420nm Light Yield: 27000 photons/MeV Time Constant: 40ns Geometry: 2x2x20 mm3 APDs Operating Voltage: 350-450V Dark Current: ≤10nA Gain uniformity (sub-array): ±15% Detector Plates 6144 crystals 12288 readout channels 160x180 mm2 surface area Front-back readout for DoI measurement 8

Frontend ASIC Characteristics Technology: CMOS 0.35μm Area: 70mm2 Input: 192 channels Output: 2 highest channels Max Input Charge: 90 fC Noise: ENC ~ 1300 e- Shaping: 40ns Analog Memories: 10 samples Clock Frequency: 50-100MHz Power: 3.6 mW/channel 9

Frontend (FE) Electronics Frontend Board Processes 384 APD channels Contains 2 ASICs for signal selection 2 High-speed ADCs (10bit, 100MHz) 1 LVDS transmitter (600Mbps) Supermodule Comprises 2 FE Boards Processes 768 APD channels Detector Plate Comprises 8 Supermodules Processes 6144 APD channels Contains one Service Board to control 192 high-voltage lines as well as power supply, clock distribution, temperature monitoring and threshold settings 10

FE Electronics Performance Pulse Shape Amplifier response rise time: 20ns Variation in baseline <0.5% Noise ENC = 1300 e- r.m.s. Inter-channel dispersion ~ 8% (2.2 ADC Counts = 5keV) (Noise measurements obtained with full electronics chain) 11

Data Acquisition Electronics (DAE) DAE Crate System DAE housed in a single 19” rack crate Uses two cPCI backplanes 1 TGR/DCC Board 4 DAQ Boards FE - DAE bandwidth up to 19.2Gbps Sophisticated coincidence trigger (36k calibration constants) DAE-Acq Server bandwidth up to 6.4Gbps 12

Data Acquisition Electronics (DAE) DAQ Board (Slave) Check Signal’s Integrity Calculate Basic Signal’s Parameters Signal’s Classification Send Relevant Data to TGR/DCC Board Built on two 4-million gate Virtex-II FPGA System composed by 4 boards 13

Data Acquisition Electronics (DAE) TRG/DCC Board (Master) DAQ Boards’ Arbitration Data Concentration Find Coincidences Sends Relevant Data to Acq Server Control Circuit Gateway System’s Synch and Reset Relies on a 3-million gate Virtex-II FPGA S-Link bridge to Acq Server 14

Data Acquisition Electronics Performance Trigger Performance Events in coincidence up to 4.5MHz (This involves computation of energy and time as well as Compton grouping and transmission to the trigger processor) Acquisition rate up to 0.8MHz (This involves readout of the event dataframe after the issueing of a trigger) Disk storage > 300MBps 15

Simulations Simulation Model NURBS CArdiac Torso (NCAT) Phantom Detector detailed description Standard injection of 10mCi (370MBq) Background tissue SUV: 2.12kBq/ml Lesions SUV: (4:1) 8.5kBq/ml (5:1) 10.5kBq/ml Exam Duration: 5 minutes W. P. Segars,"Development of a new dynamic NURBS-based cardiac-torso (NCAT) phantom", PhD dissertation, The University of North Carolina, May 2001 16

Simulations 17

ClearPEM Images Image Setup Results 1mm 22Na source Grid with 5mm pitch Two acquisitions with orthogonal plate orientations for each source location (400-600 keV) Reconstruction of 16 source positions Results Horizontal FWHM: 1.3mm Vertical FWHM: 1.2mm OSEM-2D OSEM-3D 18

Clinical Trials Phase 1 Phase 2 Tuning the image reconstruction with real cases Phase 2 Assessment of PEM sensitivity / specificity Comparison to mammography, MRI, WB-PET 19

Conclusions ClearPEM technological developments were successfully completed Excellent detector performance ClearPEM electronics is one of the most innovative systems available for APD-based PET systems Next steps: scanner characterization and clinical tests 20

Thank you! 谢 大 家 Pedro Lousã pedro.lousa@inov.pt ClearPEM Consortium RT 2009 Conference