Advanced instrumentation is critical to collecting quality data. For example, the Gordon Center has two head scanners, NeuroPET I and NeuroPET-CT II, that have been employed in brain studies for tau imaging, and for monitoring proton therapy. A novel collimator for CeraSPECT is available for SPECT imaging of the brain. We also make custom cardiac and respiratory phantoms to study imaging with motion. To process the collected data, a new, powerful computer cluster has recently come online.
High Sensitivity Brain PET
We have received the first prototype of a newly developed mobile NeuroPET scanner that is a dedicated to brain PET imaging system with a FOV of 27-cm in diameter and 24-cm in length. The scanner is mobile and was designed to achieve high sensitivity and good spatial resolution, and at low cost. It was recently installed at Massachusetts General Hospital. The performance of this new system has been investigated using procedures based on the NEMA 2001 PET standard and ACR Accreditation Program.
Spatial resolution was measured using a 22Na point source. The transverse resolution is 2.8 mm near the center and becomes 5.3 mm at a distance of r=10 cm from the center. The axial resolution is 4.7 mm at the center and 4.3 mm at r=10 cm. Because the reconstruction algorithm provided by the manufacturer assigns a weight to each event based on both energy and time information, weighted NEC rates were calculated. The weighted maximum NEC rate of 15 kcps was achieved for an activity of 35.5 MBq. The overall system sensitivity for true events is 18.8 and 21.6 cps/kBq in the center and 10 cm off the center of FOV, respectively, using an energy threshold of 200 keV. The results of NeuroPET compare favorably to those reported for other PET scanners.
High Sensitivity Brain PET/CT: NeuroPET/CT
We now have the second generation NeuroPET scanner, this one with an integrated CT component. This scanner is the first mobile brain PET/CT scanner available. The PET imaging system has a transaxial FOV of 25 cm and axial FOV of 22 cm. It uses 155316 2.3×2.3×10mm LYSO crystals (dual-layers) and 12096 SiPMTs. The scanner is mobile and can be transported on wheels to any desired location and used with any patient bed of adjustable height. The CT scan is performed by moving the scanner on precise treads, rather than moving the patient bed. The CT has 3264 detector channels with 8 axial channels at spacing of 1.25mm. The X-ray source, capable of 140 keV at 7.0 mA, can rotate at 60 rpm for 1440 views/sec. The scanner was designed to achieve high sensitivity and good spatial resolution, and at low cost. It was recently installed at Massachusetts General Hospital and is currently being used for several animal studies, and for the PET monitoring of proton therapy project. The performance of this new system has been investigated using procedures based on the NEMA 2012 PET standard and ACR Accreditation Program.
Spatial resolution was measured using a 22Na point source. The transverse resolution is 3.2 mm near the center and becomes 4.3 mm at a distance of r=10 cm from the center. The axial resolution is 3.5 mm at the center and 4.0 mm at r=10 cm. The maximum NEC rate of 19.5 kcps was achieved for an activity concentration of 2.9 kBq/ml. The overall system sensitivity for true events is 11.6 and 13.9 cps/kBq in the center and 10 cm off the center of FOV, respectively, using an energy threshold of 300 keV. The results of NeuroPET/CT compare favorably to those reported for other PET scanners.
Grogg KS, Toole T, Ouyang J, Zhu X, Normandin MD, Li Q, Johnson K, Alpert NM, El Fakhri G. National Electrical Manufacturers Association and Clinical Evaluation of a Novel Brain PET/CT Scanner. J. Nucl. Med. 2016; 57(4):646-52
View in: PubMed
Whole Body PET/CT
The Gordon Center is equipped with a GE whole-body MI-Discovery TOF-PET/CT. This 5-ring system was installed in January 2018. It has extended axial field of view (25 cm), 128 slice CT, 136 block detectors each of which comprising a 4×9 array of LYSO crystals (3.94×5.3x25mm). Timing resolution is sub-400ps FWHM. This system is dedicated exclusively to clinical research studies and animals studies.
High Sensitivity Brain SPECT
Sensitivity near the center of the brain is critical for some clinical applications of brain SPECT, especially for those applications which require dynamic imaging. We have designed and built a novel collimator for the CeraSPECT dedicated brain SPECT system which uses variable focusing to increase the sensitivity for central regions of its field of view. The sensitivity at the center of the field of view is increased by a factor of two compared to the standard three-segment parallel-hole collimator; this sensitivity gain is achieved without compromising spatial resolution.
El Fakhri G., Ouyang J., Zimmerman R.E., Fischman A.J., Kijewski M.F.
Performance of a Novel Collimator for High-Sensitivity Brain SPECT. Med. Phys.
2006; 33:209-215. [PDF]
Ouyang J., El Fakhri G., Xia W., Kijewski M.F., Genna S. The Design and
Manufacture of an Annular Variable-focusing Collimator for High-sensitivity
Brain SPECT. IEEE Trans Nucl Sci 2006; 53: 2613-2618.
Advanced Radiation Detector Systems
Under this program we develop advanced radiation detector systems for nuclear medicine, intraoperative imaging probes, and computed tomography applications by rigorously studying and addressing some of the fundamental obstacles on the way of such high-performance imaging systems. The main research goal is to develop novel and cost-effective platform to fabricate radiation detectors using laser processed scintillators. By using laser-induced optical barriers (LIOB) technology we are seeking new designs of scintillator detectors for PET, SPECT, and CT imaging modalities that were not possible before. In LIOB, a pulsed laser beam is focused inside the scintillator bulk. An optimized pulse with respect to the wavelength, pulse energy and duration, refractive index of the crystal, etc can locally alter the crystal structure thus creating an optical barrier that has different index of refraction with respect to its immediate surrounding media. These optical barriers behave as reflectors and can be used to manipulate the spread of the scintillation light to achieve spatial resolution.
High-resolution and high-sensitivity with DOI PET scanner for small animal imaging
The focus of this project is to develop high-performance and cost-effective detector for MRI-compatible small animal PET imaging. The goal is develop sub-millimeter spatial resolution detectors with depth of interaction (DOI) capability while maintaining high sensitivity to the incident 511 keV gamma rays by using 15-25 mm thick L(Y)SO:Ce scintillator. Using LIOB technique, we are developing detectors with built-in optical micro-structures to manipulate the spread of scintillation light and achieve 3D spatial information.
Performance of the LYSO:Ce crystal with 0.77 mm pixels coupled with 4×4 SiPM array (4.2 mm pixel pitch).
H. Sabet, H. Kudrolli, B. Singh, V.V. Nagarkar, Fabricating high-resolution and high-sensitivity scintillator arrays using Laser Induced Optical Barriers, IEEE NSS-MIC, pp. 4080 – 4084, 2012
Cardiac and respiratory phantoms
We have constructed several custom-made phantoms to study motion from heart beat and respiration during imaging.
- Positrons (internal link): Beowulf cluster with one master node and five computing nodes, including a total of 120 logical processors, 384 GB memory, and 36 TB disk space, and is capable of running both 32- and 64-bit applications.
- Boson: A global shared memory (ccNUMA interconnect) Silicon Graphics UV 2000 supercomputer. The hardware consists of 32 2-processor 8-core Intel Xeon E5-4640 2.4 GHz processing nodes (512 cores, 1024 threads), 3 terabytes of RAM and 120 terabytes of disk storage. System performance is 9.83 teraflops and includes the high-performance SGI InfiniteStorage 5000 storage system with 4 GB cache and 6Gb/s Fibre Channel architecture for data throughput.
- C57B, Alzheimer transgenic, Diabetic transgenic
- NOD.CB17-Prkdcscid Il2rgtm1Wjl/SzJ (NOD/SCID)
- Fischer Wistar – Rattus norvegicus
- TgF344-AD (expressing mutant genes identified in Alzheimer’s Diseases patients)
- RNU Nude
- Macaque Rhesus
Other large animals
- Rabbits: New Zealand White
- Woodchucks : Eastern woodchuck – Marmota monax
- Pigs : Yorkshire