Development of New Detectors for PET Imaging at BNL DOE/JLAB Meeting Bethesda, MD May 20, 2004 Craig Woody Physics Dept Brookhaven National Lab RatCAPBeta Microprobe

C.Woody, DOE/JLAB Meeting, 5/20/042 The RatCAP Project Part of a larger project for Imaging The Awake Animal also involving motion tracking in both PET and MRI SUNY BNL

C.Woody, DOE/JLAB Meeting, 5/20/043 RatCAP: Rat Concious Animal PET Mockup of the portable ring on the head of a rat Readout chip APD LSO Socket Ring containing 12 block detectors of 2x2 mm 2 x 5 mm deep LSO crystals with APDs and integrated readout electronics

C.Woody, DOE/JLAB Meeting, 5/20/044 LSO Crystal Arrays Studying different types of crystal arrays to optimize light output and energy resolution CTI white powder reflector Proteus unbonded 3M reflector Proteus single crystals

C.Woody, DOE/JLAB Meeting, 5/20/045 Optimization of Light Collection unwrapped air unwrapped cookie wrapped cookie wrapped air Dashed = Measured Solid = Opticad OPTICAD Ray Tracing Program 2x2 mm 2 single crystals wrapped in 3M reflector and coupled with a silicone cookie to a calibrated PMT N pe /MeV = N  /MeV x  x QE 2400 = 25,000 x 0.4 x 0.24

C.Woody, DOE/JLAB Meeting, 5/20/046 Measurement of Light Output and Energy Resolution of Crystals Arrays Average light yield of final arrays ~ 5400 p.e./MeV (~ 22 % higher than prototype) All final crystal arrays have been received and tested Energy resolution ~ 16% for 137 Cs Measured with 3rd prototype ASIC  ~ 13% Total spread ~ ± 40%

C.Woody, DOE/JLAB Meeting, 5/20/047 Characterization of Avalanche Photodiodes 4x8 array 1.6 x 1.6 mm 2 active pixel area Hamamatsu S8550 N pe ~ 2700 Typical G ~ 50  ~ 135K signal e’s Common voltage for each 16 channels Dark current < 40 nA (~ 1.2 nA/ch) Expected noise in final ASIC ~ 1100 e’s (C T ~ 10 pF) G ~ 50 All final APD arrays have been received and tested

C.Woody, DOE/JLAB Meeting, 5/20/048 Test Setup with Crystal and APD Arrays Two arrays of 4x8 APDs and crystals using hybrid preamps and shapers and CAMAC DAQ system

C.Woody, DOE/JLAB Meeting, 5/20/049 Source Images Single 1 mm dia. 68 Ge point source 1.6 mm off axis 2 mm Multiple 68 Ge point sources (~ 2mm) spaced ~ 4 mm 4 mm

C.Woody, DOE/JLAB Meeting, 5/20/0410 Wrist Monitor for Measuring the Arterial Input Function For human studies, the input function is taken from the radial artery in the wrist. Activity in the surrounding veins produce a significant background which can be rejected using the good spatial resolution of the wrist monitor. Planar image of a 1 mm diameter 68 Ge line source Wrist Phantom

C.Woody, DOE/JLAB Meeting, 5/20/0411 Beta Scintillation Microprobe Radioisotopes used in PET emit positrons with energies of a few hundred keV which have a range of several mm in blood or tissue. This range is comparable to the spatial resolution obtained in most PET cameras. These positrons can be detected directly using plastic or crystal scintillators. With crystal scintillators which have high density, the positrons will range out, depositing all of their energy in the crystal and producing a large signal. Small scintillation probes can be used to directly measure the radiotracer concentration in the blood or tissue.

C.Woody, DOE/JLAB Meeting, 5/20/0412 Probe Construction LSO microprobe consisting of 0.5 mm diameter x 1.5 mm long LSO crystal wrapped with several layers of white reflecting teflon and covered with polyester shrink tubing.

C.Woody, DOE/JLAB Meeting, 5/20/0413 Rat Brain Studies with Microprobe Uptake of 11 C-methylphenidate in the nucleus accumbens region of a rat brain with LSO probe nucleus accumbens ~ 2 mm

C.Woody, DOE/JLAB Meeting, 5/20/0414 Input Function Measured with Microprobe LSO microprobe (0.3 mm dia. x 0.5 mm) inserted inside an 18 gauge syringe needle for blood flow study. Activity of 11 C-tyrosine measured in baboon blood flow during a PET scan using a syringe mounted LSO microprobe. Input function

C.Woody, DOE/JLAB Meeting, 5/20/0415 Related Detector R&D in the Physics Department RHIC The PHENIX group in the Physics Department works closely with Chemistry, Instrumentation and Medical on detector development for medical imaging

C.Woody, DOE/JLAB Meeting, 5/20/0416 Areas of Detector Development Scintillating crystals (LSO, PWO, BaF 2, CsI, CeF 3, PbF 2,...) Photodetectors (PMTs, APDs, solid and gaseous deep UV photocathodes,...) Micropattern gas detectors (GEMs, Micromegas,...) Time Projection Chambers (PHENIX, STAR detector upgrades) Calorimetry (Pb/Sc, Si/W  PHENIX upgrades) High speed DAQ and trigger (PHENIX) Offline data processing (PHENIX) Areas of overlap with detector development for medical imaging