Prostate probe with SPECT technique NSS – MIC November 5 - KnoxvilleF. Garibaldi- INFN – Roma1 – gr. Coll. ISS  the medical problem  the proposal  Layout  Multimodality  SiPM/electronics  summary and outlook 1

Radionuclides imaging techniques Patient injected with radioactive drug. Drug localizes according to its metabolic properties. Gamma rays, emitted by radioactive decay, that exit the patient are imaged. 1.Collimator Only gammas that are perpendicular to imaging plane reach the detector 2.Scintillator Converts gammas to visible light 3.Photodetector Convert light to electrical signal 4.Readout Electronics Amplify electrical signal and interface to computer 5.Computer decoding procedure Elaborate signal and gives image output

PET Compton Camera mechanical collimation Multi pinhole

Single photon techniques - simple(r) - cheape(r) - extending the radiotracers available - dual tracer  looking at two different biological processes pros cons - efficiency - spatial resolution

Compton Prostate Imaging Probe Internal Compton ProbeExternal Compton Probe

Conventional SPECT Reconstructions 5:110:115:120:1 w / tumor bkgd 171 and 245 keV, 8.8M events / 40 slices Spatial resolution ~15mm FWHM Prostate

Compton Prostate Probe Reconstructions 5:110:115:120:1 w / tumor bkgd 245 keV only, 1.2 million events, 8mm lesion Prostate Spatial resolution ~2mm FWHM

Internal Detector Details 10–12 layers of 1mm thick Si detectors + position and orientation sensor Exploded View Assembled Unit

Detector Packaging Unfolded energy spectrum “Raw” energy spectrum Use Tape Automated Bonding (TAB) (Very thin kapton tape with aluminum traces) Kapton microcables Detector VATA ASIC Kapton “hybrid” board

Demise of the Compton Prostate Probe Decreasing interest in imaging single photon agents “Coincidence” PET cameras not reimbursed by HCFA Technology ultimately was a bit far off

Single photon Compton camera ( N. Clinthorne. Michigan )

W. Moses – Rome workshop 2005

111 In-ProstaScint is not a good radiotracer but a new one proposed by M. Pomper looks promising. Radionuclides Single photon The single photon endorectal probe provides 2D imaging. We have to try to have 3 D images ( using multipinhole collimation and/or adding up a SPECT tomograph (spatial resolution would be dominated by the small probe (see later, the PET case ))

our proposal -insert scintillator pixels into square holes of the collimator  better performances (spatial resolution (?) and sensitivity (thicker scintillator)) -using diverging collimator  better performances (reducing scan time) -using multipinhole collimation  better performances (increasing sensitivity, tomographic recinstruction)

New radiotracers coming soon (M. Pomper, Johns Hopkins) Radiotracers available for SPECT and PET (from “New agents and Techniques for Imaging prostate cancer” A. Zahreer, S. Y. Cho, M. Pomper”, to be published on JNM ) SPECT: Prostascint, Bombesyn, 99mTechnetium nanocolloid (limphonodes), other coming soon … PET C—11 Choline, F-18-Choline, Ga-68 Dotabomb (Hofmann (Rome workshop)) many others coming… (collaboration with Johns Hopkins for testing in ISS (mice models for prostate available) and/or at JHU) 16