PowerPoint Presentation

RAD2012, Nis, SerbiaPositron Detector for radiochemistry on chip applications

R. Duane, N. Vasovi, P. LeCoz, N. Pavlov1, C. Jackson1, A. Jaki

1) Sensl technologies (www.sensl.com)

www.tyndall.ieThank you very much. This work was 1OUTLINERadiochemistry On Chip (ROC) European ProjectProduction of radiotracers for Positron Emission Tomography (PET) analysisSilicon Photomultiplier Technology

Miniature Radiation Probes

Summary

www.tyndall.ieQuickly give background to work followed by a short introduction to silicon photomultiplier technology2Positron Emission Tomography

Injection of positron emitting radiotracer (e.g. F-18 combination with glucose biomarker = FDG)

www.tyndall.iePET starts with an injection of positron emitting isotope like F18. This would be combined with a biomarker like glucose to produce FDG.3Commercial production of RadiotracersCyclotron to produce the radioactive isotope (e.g. F-18, C-11)Hot-cells to combine radioisotopes with biomarker such as glucose analog

+

=Fludeoxyglucouse (FDG)www.tyndall.ieOur project was looking at production of the radiotracers4Radiochemistry on Chip (ROC) Motivation

Technical Goal: Microfluidic synthesis platformMotivation: On-site production of PET radiotracerswww.tyndall.ieLengthy process of production and distribution from special labs to hospitals5Microfluidic Synthesis Platform

RadioTracerWaste Lines

www.tyndall.ieSimple flow diagram of the platform6Radiation Detection ObjectivesFlow ProbeWaste ProbeTrack movement of FDG radioactivity in 1m3 Lead Box High concentrations of positron and annihilation gammas (1Tbq total F18 activity)

Shielded probes to quantify activity in waste and flow shielded chambers

Unshielded positron probe to track small changes in positron activity in microfluidic chips as process monitor

microreactor

Positron Probewww.tyndall.ieOriginally going to talk about positron probe also but one of our partners asked us not to discuss details at this stage of development7Shielded probe requirements/designActivity: 3.7kBq/100uL (waste) to 740Mbq/uL (flow)Size: approx 1-2cm3 (due to microfluidic chip sizes)Scintillator based detectorMagnetic Field Immunity due to proximity to mini-cyclotronSemiconductor (Silicon) based photodetector Count linearity and stability (106)

www.tyndall.ieSensl Silicon Photomultiplier

Sensl Silicon Photomultiplier (SPM)Silicon Photomultiplier (SPM) = Array of Geiger Mode photodiodes3,640 35um geiger mode diodes per 3mm dieReplaces PhotoMultiplier Tube (PMT)

Low voltage 30V operationDirect gamma hits are not an issue due to device designExpect good count linearity for gamma detectorLarge signal to noise ratio results in simpler electronics and longer cabling

www.tyndall.ieBest solution is gamma scintillator plus spm11Sensl Silicon Photomultiplier Probes

Inorganic ScintillatorSPM

www.tyndall.ieCSI (TI) Probe Results

CSI (TI) chosen as best spectral match (550nm) to SPM peak light absorption (520nm) Peak Resolution 8.7% Cs137 , 10.5% Ge68511kev667kev

www.tyndall.ieEnergy linearity shows probe and electronics working well13CSI(TI) Probe Results

Distinguish minimum waste activity (1.5kBq) in lab environment at room temperatureStability of 4.7% (139kBq) over 12 hour measurement (1s integration time) Meets 5% specification for flow probeExpect better stability for 740MBq flow activitiesBackgroundMinimum Wastewww.tyndall.ieCSI(TI) Probe Linearity

Good linearity for low waste activities(1.5kBq-139kBq) using peak countingPeak Sensitivity = 30counts/second/kBq (at 6mm distance from disc source)

www.tyndall.ie15CSI (TI) Flow Probe Saturation of measured counts (Peak counting) CSI(TI) scintillator 1ms pulse and associated 3ms shaping time

www.tyndall.ieLSO Flow Probe

LSO scintillator (3mm) investigated for flow probe Faster gamma response (40ns) Poorer spectral matching (440nm peak photon emission)10s integration timewww.tyndall.ieLSO Flow Probe

Good fit to 1Gbq F-18 decay over 20 hours (Total counting)5 second integration time

109.74min F-18 half-life

www.tyndall.ieSUMMARYSilicon Photomultiplier based probes for radiochemistryCSI(TI) +SPM waste probeLSO + SPM flow probe

Preliminary results show good count linearity and stability

Temperature compensation circuitry for SPM gain in development

Welcome collaborators with access to high activity positron sources Stability, Linearity as a function of temperatureRadiation Hardness

www.tyndall.ieThank you for your attention!!!

www.tyndall.ie