Andrew LaBella is awarded the 2019 Valentin T. Jordanov Radiation Instrumentation Travel Grant. Andy is the first author on all three papers accepted from Goldan Lab at the IEEE NSS/MIC conference in Manchester, UK. The papers cover topics ranging from our revolutionary and patented Prism-PET technology for ultra-high spatial resolution and ultra-high sensitivity TOF-DOI-Compton PET, to 100 ps TOF PET, and finally utilizing convolutional neural networks (CNNs) for enhanced 3D gamma-ray localization. For more information, please click here.
Dr. Goldan has received a new NIH grant entitled “SWAD: Large-Area Photon Counting X-Ray Imager Using Amorphous Selenium”.
In this NIH R01 grant, we proposed to develop a prototype hyperspectral photon counting imager using the field-Shaping multi-Well Avalanche Detector (SWAD) for high spatial resolution contrast-enhanced x-ray breast imaging. Given that the photosensor material is amorphous, the detector structure is inherently inexpensive, and thus, it enables a cost-effective imager design with large area scalability. Also, the photon counting imager will permit quantum-noise-limited performance, energy weighting, high frame-rates, and multi-energy thresholding. The technological innovation we develop will lead to the widespread clinical application of a more efficient and lower dose contrast-enhanced cancer screening system for mammography.
Andrew LaBella publishes his first paper on “Picosecond Time Resolution with Avalanche Amorphous Selenium.”This paper appeared as a supplementary cover in ACS Photonics, vol. 6, issue 6. Congratulations Andy!
Picosecond timing in an avalanche amorphous selenium semiconductor is achieved by implementing Nano-Frisch grids along the collecting electrode to form a multiwell structure. The induced photocurrent following optical impulse exposure is independent of carrier motion outside the wells resulting in unipolar time-differential charge sensing via extended-state hot hole transport. This is the first experimental report of avalanche gain and picosecond time-resolution using an amorphous semiconductor. Further analysis suggests we may be able to achieve sub-100 picosecond coincidence timing resolution in time-of-flight PET using our multiwell selenium semiconductor as the photodetector.
Atreyo Mukherjee publishes his first paper on “Hole transport in selenium semiconductors using density functional theory and bulk Monte Carlo.” Congratulations Atreyo!
In this paper, we have considered effective mass approximations in the case of phonon-limited hole transport in selenium semi-conductors combined with simulated deformation potentials and Monte Carlo (MC) solutions to the Boltzmann transport equation (BTE). This method allows us to obtain microscopic access to carrier trajectories and relaxation dynamics, driven by acoustic and optical phonons, and ultimately calculate the low-field differential drift mobility and observe high field runaway effects. We first utilized density functional theory (DFT) simulations to calculate the density of states and acoustic/optical deformation potentials for the crystalline phases.
In general, we showed how holes in selenium can undergo both elastic (momentum relaxation) and inelastic (energy and momentum relaxation) collisions and yet get “hot,” thus gaining energy at a higher rate from the electric field than they lose to the lattice vibrations in the form of phonon scattering.
Dr. Goldan has been promoted to tenure-track assistant professor at Stony Brook University in the department of Radiology.
We are recruiting two PhD candidates and one Post Doctoral fellow for our work on medical imaging detectors. If you are interested, please forward your CV to Amirhossein.Goldan@stonybrookmedicine.edu. To learn more about our research, please click here.
AAPM showcases the ‘best in physics’
Selenium ramps TOF-PET performance
In the imaging category, Andrew LaBella from SUNY Stony Brook University described NEW-HARP, an amorphous selenium photodetector for time-of-flight (TOF) PET. The aim of NEW-HARP (nano-electrode multi-well high-gain avalanche rushing photoconductor) is to achieve a sufficient time resolution to perform TOF-PET in simultaneous PET/MRI.
Dr. Goldan was a recipient of the 2018 National Academy of Inventors (NAI) award.
Dr. Goldan is awarded his second NIH-R21 (NIBIB Trailblazer) grant for the feasibility study of a novel high-efficiency avalanche detector for high resolution x-ray imaging applications.
The proposed detector features a very thin layer of ultra-high efficiency Cadmium Selenide (CdSe), while coupled to a thicker multi-well avalanche amorphous selenium (a-Se) film, to serve as the photoelectric conversion layer for further enhancing the low-dose x-ray sensitivity (in addition to having avalanche gain inside a-Se). This project is inspired by the commercial success of solution-processed and highly tunable colloidal quantum dots (e.g., release of the first Quantum-Dot LED or QLED TV in 2015) for the formation of the CdSe layer. This project is in close collaboration with Professor Wei Zhao of Radiology who is also the Co-PI on this 3-year grant.
Dr. Goldan is awarded his first NIH-R21 grant for the feasibility study of picosecond avalanche selenium detectors for time-of-flight (TOF) PET.
The latest integration of PET with MR has greatly advanced the clinical capability in cancer detection, staging, and monitoring of treatment. A time-of-flight (TOF) PET system uses timing information to determine if two registered photons are in “time coincidence” (in which case they belong to the same positron annihilation event), and uses the arrival time difference to localize each annihilation event. The use of TOF information in PET enables (1) simultaneous PET/MR imaging with enhanced resolution (especially for obese patients), (2) improved lesion detectability, and (3) shorter examination time with coregistration. Furthermore, TOF-PET has already shown to substantially reduce artifacts that are induced by MR imaging-based attenuation correction. Thus, TOF-PET/MR has immense potential to become a “one-stop shop” imaging technology that provides simultaneous functional, molecular and morphologic assessments of neurologic, cardiovascular, onco- logic, and musculoskeletal diseases. However, existing state-of-the-art TOF-PET/MR systems (such as the recently introduced SIGNA TOF PET/MR system developed by GE) all utilize a detector ring based on silicon photomultipliers (SiPMs) which still require further improvement to enhance cells’ photon detection e ciency (PDE), reduce optical crosstalk, and increase uniformity and yield. These problems cause the TOF imaging system to have suboptimal clinical effectiveness. In addition, the relatively high cost and small area of SiPMs prohibits large axial field-of-view to maximize geometric detection e ciency and approach the fundamental sensitivity limits of PET. Our hypothesis is that a novel low-cost amorphous selenium (a-Se) detector structure with avalanche multiplication gain and unipolar time differential (UTD) charge sensing can have optimal coincidence timing resolution (CTR) for TOF-PET. The objective of this exploratory R21 proposal is to demonstrate the feasibility of a-Se for TOF-PET by building single pixels on a glass substrate and measuring their CTR.