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Author (up) Brzezinski, K.; Oliver, J.F.; Gillam, J.; Rafecas, M.; Studen, A.; Grkovski, M.; Kagan, H.; Smith, S.; Llosa, G.; Lacasta, C.; Clinthorne, N.H. doi  openurl
  Title Experimental evaluation of the resolution improvement provided by a silicon PET probe Type Journal Article
  Year 2016 Publication Journal of Instrumentation Abbreviated Journal J. Instrum.  
  Volume 11 Issue Pages P09016 - 13pp  
  Keywords Gamma camera; SPECT; PET PET/CT; coronary CT angiography (CTA); Medical-image reconstruction methods and algorithms; computer-aided software  
  Abstract A high-resolution PET system, which incorporates a silicon detector probe into a conventional PET scanner, has been proposed to obtain increased image quality in a limited region of interest. Detailed simulation studies have previously shown that the additional probe information improves the spatial resolution of the reconstructed image and increases lesion detectability, with no cost to other image quality measures. The current study expands on the previous work by using a laboratory prototype of the silicon PET-probe system to examine the resolution improvement in an experimental setting. Two different versions of the probe prototype were assessed, both consisting of a back-to-back pair of 1-mm thick silicon pad detectors, one arranged in 32 x 16 arrays of 1.4mm x 1.4mm pixels and the other in 40 x 26 arrays of 1.0mm x 1.0mm pixels. Each detector was read out by a set of VATAGP7 ASICs and a custom-designed data acquisition board which allowed trigger and data interfacing with the PET scanner, itself consisting of BGO block detectors segmented into 8 x 6 arrays of 6mm x 12mm x 30mm crystals. Limited-angle probe data was acquired from a group of Na-22 point-like sources in order to observe the maximum resolution achievable using the probe system. Data from a Derenzo-like resolution phantom was acquired, then scaled to obtain similar statistical quality as that of previous simulation studies. In this case, images were reconstructed using measurements of the PET ring alone and with the inclusion of the probe data. Images of the Na-22 source demonstrated a resolution of 1.5mm FWHM in the probe data, the PET ring resolution being approximately 6 mm. Profiles taken through the image of the Derenzo-like phantom showed a clear increase in spatial resolution. Improvements in peak-to-valley ratios of 50% and 38%, in the 4.8mm and 4.0mm phantom features respectively, were observed, while previously unresolvable 3.2mm features were brought to light by the addition of the probe. These results support the possibility of improving the image resolution of a clinical PET scanner using the silicon PET-probe.  
  Address [Brzezinski, K.; Oliver, J. F.; Gillam, J.; Rafecas, M.; Llosa, G.; Lacasta, C.] Univ Valencia, CSIC, Inst Fis Corpuscular, C Catedrat Jose Beltran 2, Valencia, Spain, Email: k.w.brzezinski@rug.nl  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1748-0221 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000387862300016 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2865  
Permanent link to this record
 

 
Author (up) Clinthorne, N.; Brzezinski, K.; Chesi, E.; Cochran, E.; Grkovski, M.; Grosicar, B.; Honscheid, K.; Huh, S.; Kagan, H.; Lacasta, C.; Linhart, V.; Mikuz, M.; Smith, D.S.; Stankova, V.; Studen, A.; Weilhammer, P.; Zontar, D. doi  openurl
  Title Silicon as an unconventional detector in positron emission tomography Type Journal Article
  Year 2013 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A  
  Volume 699 Issue Pages 216-220  
  Keywords PET; Silicon detectors; Multiresolution imaging; Magnifying PET  
  Abstract Positron emission tomography (PET) is a widely used technique in medical imaging and in studying small animal models of human disease. In the conventional approach, the 511 keV annihilation photons emitted from a patient or small animal are detected by a ring of scintillators such as LYSO read out by arrays of photodetectors. Although this has been successful in achieving similar to 5 mm FWHM spatial resolution in human studies and similar to 1 mm resolution in dedicated small animal instruments, there is interest in significantly improving these figures. Silicon, although its stopping power is modest for 511 keV photons, offers a number of potential advantages over more conventional approaches including the potential for high intrinsic spatial resolution in 3D. To evaluate silicon in a variety of PET “magnifying glass” configurations, an instrument was constructed that consists of an outer partial-ring of PET scintillation detectors into which various arrangements of silicon detectors are inserted to emulate dual-ring or imaging probe geometries. Measurements using the test instrument demonstrated the capability of clearly resolving point sources of Na-22 having a 1.5 mm center-to-center spacing as well as the 1.2 mm rods of a F-18-filled resolution phantom. Although many challenges remain, silicon has potential to become the PET detector of choice when spatial resolution is the primary consideration. (C) 2012 Elsevier B.V. All rights reserved.  
  Address [Clinthorne, Neal; Huh, Sam] Univ Michigan, Dept Radiol, Ann Arbor, MI 48109 USA, Email: nclintho@umich.edu  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0168-9002 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000312809200045 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1290  
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Author (up) Grkovski, M.; Brzezinski, K.; Cindro, V.; Clinthorne, N.H.; Kagan, H.; Lacasta, C.; Mikuz, M.; Solaz, C.; Studen, A.; Weilhammer, P.; Zontar, D. doi  openurl
  Title Evaluation of a high resolution silicon PET insert module Type Journal Article
  Year 2015 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A  
  Volume 788 Issue Pages 86-94  
  Keywords Positron emission tomography; Silicon detectors; PET insert; Image reconstruction  
  Abstract Conventional PET systems can be augmented with additional detectors placed in close proximity of the region of interest. We developed a high resolution PET insert module to evaluate the added benefit of such a combination. The insert module consists of two back-to-back 1 mm thick silicon sensors, each segmented into 1040 1 mm(2) pads arranged in a 40 by 26 array. A set of 16 VATAGP7.1 ASICs and a custom assembled data acquisition board were used to read out the signal from the insert module. Data were acquired in slice (20) geometry with a Jaszczak phantom (rod diameters of 12-4.8 mm) Filled with F-18-FDG and the images were reconstructed with ML-EM method. Both data with full and limited angular coverage from the insert module were considered and three types of coincidence events were combined. The ratio of high-resolution data that substantially improves quality of the reconstructed image for the region near the surface of the insert module was estimated to be about 4%. Results from our previous studies suggest that such ratio could be achieved at a moderate technological expense by using an equivalent of two insert modules (an effective sensor thickness of 4 mm).  
  Address [Grkovski, Milan; Cindro, Vladimir; Mikuz, Marko; Studen, Andrej; Zontar, Dejan] Jozef Stefan Inst, Ljubljana, Slovenia, Email: milan.grkovski@ijs.si  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0168-9002 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000354870700016 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2232  
Permanent link to this record
 

 
Author (up) Studen, A.; Brzezinski, K.; Chesi, E.; Cindro, V.; Clinthorne, N.H.; Cochran, E.; Grosicar, B.; Grkovski, M.; Honscheid, K.; Kagan, H.; Lacasta, C.; Llosa, G.; Mikuz, M.; Stankova, V.; Weilhammer, P.; Zontar, D. doi  openurl
  Title Silicon detectors for combined MR-PET and MR-SPECT imaging Type Journal Article
  Year 2013 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A  
  Volume 702 Issue Pages 88-90  
  Keywords PET; Silicon detectors; SPECT  
  Abstract Silicon based devices can extend PET-MR and SPECT-MR imaging to applications, where their advantages in performance outweigh benefits of high statistical counts. Silicon is in many ways an excellent detector material with numerous advantages, among others: excellent energy and spatial resolution, mature processing technology, large signal to noise ratio, relatively low price, availability, versatility and malleability. The signal in silicon is also immune to effects of magnetic field at the level normally used in MR devices. Tests in fields up to 7 T were performed in a study to determine effects of magnetic field on positron range in a silicon PET device. The curvature of positron tracks in direction perpendicular to the field's orientation shortens the distance between emission and annihilation point of the positron. The effect can be fully appreciated for a rotation of the sample for a fixed field direction, compressing range in all dimensions. A popular Ga-68 source was used showing a factor of 2 improvement in image noise compared to zero field operation. There was also a little increase in noise as the reconstructed resolution varied between 2.5 and 1.5 mm. A speculative applications can be recognized in both emission modalities, SPECT and PET. Compton camera is a subspecies of SPECT, where a silicon based scatter as a MR compatible part could inserted into the MR bore and the secondary detector could operate in less constrained environment away from the magnet. Introducing a Compton camera also relaxes requirements of the radiotracers used, extending the range of conceivable photon energies beyond 140.5 keV of the Tc-99m. In PET, one could exploit the compressed sub-millimeter range of positrons in the magnetic field. To exploit the advantage, detectors with spatial resolution commensurate to the effect must be used with silicon being an excellent candidate. Measurements performed outside of the MR achieving spatial resolution below 1 mm are reported.  
  Address [Studen, A.; Cindro, V.; Grosicar, B.; Grkovski, M.; Mikuz, M.; Zontar, D.] Jozef Stefan Inst, Ljubljana, Slovenia, Email: andrej.studen@ijs.si  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0168-9002 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000314682300026 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1331  
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