Depth-encoding using optical photon TOF in a prism-PET detector with tapered crystals.

Background: High-resolution brain positron emission tomography (PET) scanner is emerging as a significant and transformative non-invasive neuroimaging tool to advance neuroscience research as well as improve diagnosis and treatment in neurology and psychiatry. Time-of-flight (TOF) and depth-of-interaction (DOI) information provide markedly higher PET imaging performance by increasing image signal-to-noise ratio and mitigating spatial resolution degradation due to parallax error, respectively. PET detector modules that utilize light sharing can inherently carry DOI information from the multiple timestamps that are generated per gamma event.

Protocol parameter extraction and centralization framework for comprehensive and in-depth CT protocol review and management.

CT protocol management is an arduous task that requires expertise from a variety of radiology professionals, including technologists, radiologists, radiology IT professionals, and medical physicists. Each CT vendor has unique, proprietary protocol file structures, some of which may vary by scanner model, making it difficult to develop a universal framework for distilling technical parameters to a human-readable file format. An ideal solution for CT protocol management is to minimize the work required for parameter extraction by introducing a data format into the workflow that is universal to all CT scanners.

Age-specific Dose Catalog for Diagnostic Fluoroscopy and Fluoroscopically Guided Interventional Procedures from a Pediatric Hospital.

Background Fluoroscopy is an imaging modality associated with a wide range of dose levels, characterized using a variety of dose metrics, including effective dose. However, for clinical procedures, effective dose is a seldom-used and unregulated metric in the United States, and thus, it is not extensively studied in radiology despite potentially large clinical implications for patients, especially children and infants. Purpose To formulate and report a dose catalog across all diagnostic and interventional radiology (IR) fluoroscopy examination or procedure types at a specialized tertiary care pediatric hospital.

Resolving inter-crystal scatter in a light-sharing depth-encoding PET detector.

Inter-crystal scattering (ICS) in light-sharing positron emission tomography (PET) detectors leads to ambiguity in positioning the initial interaction, which significantly degrades the contrast, quantitative accuracy, and spatial resolution of the resulting image. Here, we attempt to resolve the positioning ambiguity of ICS in a light-sharing depth-encoding detector by exploiting the confined, deterministic light-sharing enabled by the segmented light guide unique to Prism-PET.We first considered a test case of ICS between two adjacent crystals using an analytical and a neural network approach.

Interleaved signal multiplexing readout in depth encoding Prism-PET detectors.

Background: Given the large number of readout pixels in clinical positron emission tomography (PET) scanners, signal multiplexing is an indispensable feature to reduce scanner complexity, power consumption, heat output, and cost.

Purpose: In this paper, we introduce interleaved multiplexing (iMux) scheme that utilizes the characteristic light-sharing pattern of depth-encoding Prism-PET detector modules with single-ended readout.

Methods: In the iMux readout, four anodes from every other silicon photomultiplier (SiPM) pixels across rows and columns, which overlap with four distinct light guides, are connected to the same application-specific integrated circuit (ASIC) channel.

A conformal TOF-DOI Prism-PET prototype scanner for high-resolution quantitative neuroimaging.

Background: Positron emission tomography (PET) has had a transformative impact on oncological and neurological applications. However, still much of PET's potential remains untapped with limitations primarily driven by low spatial resolution, which severely hampers accurate quantitative PET imaging via the partial volume effect (PVE).

Purpose: We present experimental results of a practical and cost-effective ultra-high resolution brain-dedicated PET scanner, using our depth-encoding Prism-PET detectors arranged along a compact and conformal gantry, showing substantial reduction in PVE and accurate radiotracer uptake quantification in small regions.

Nanopattern multi-well avalanche selenium detector for TOF-PET.

For the first time, we propose using amorphous selenium (-Se) as the photoconductive material for time-of-flight (TOF) detectors. Advantages of avalanche-mode-Se are having high fill factor, low excess noise due to unipolar photoconductive gain, band transport in extended states with the highest possible mobility, and negligible trapping. The major drawback of-Se is its poor single-photon time resolution and low carrier mobility due to shallow-traps, problems that must be circumvented for TOF applications.

Sub-2 mm depth of interaction localization in PET detectors with prismatoid light guide arrays and single-ended readout using convolutional neural networks.

Purpose: Depth of interaction (DOI) readout in PET imaging has been researched in efforts to mitigate parallax error, which would enable the development of small diameter, high-resolution PET scanners. However, DOI PET has not yet been commercialized due to the lack of practical, cost-effective, and data efficient DOI readout methods. The rationale for this study was to develop a supervised machine learning algorithm for DOI estimation in PET that can be trained and deployed on unique sets of crystals.

Prismatoid light guide array for enhanced gamma ray localization in PET: a Monte Carlo simulation study of scintillation photon transport.

High spatial resolution PET relies on having excellent depth-of-interaction (DOI) resolution and small detector elements. Depth-encoding in PET modules has traditionally been performed using dual-ended readout. In recent years, researchers have explored the feasibility of replacing the second readout array with a light guide at the entrance layer that introduces intercrystal light sharing in order to reduce cost and and make depth-encoding modules more compact.

High-Resolution Depth-Encoding PET Detector Module with Prismatoid Light-Guide Array.

Depth-encoding detectors with single-ended readout provide a practical, cost-effective approach for constructing high-resolution and high-sensitivity PET scanners. However, the current iteration of such detectors uses a uniform glass light-guide to achieve depth encoding, resulting in nonuniform performance throughout the detector array due to suboptimal intercrystal light sharing. We introduce Prism-PET, a single-ended-readout PET detector module with a segmented light-guide composed of an array of prismatoids that introduce enhanced, deterministic light sharing.

Picosecond Time Resolution with Avalanche Amorphous Selenium.

Ultrafast photodetection has traditionally been performed with crystalline photodetectors, which tend to suffer from low production yield, suboptimal detection efficiency, and operational limitations that restrict their potential applications. Amorphous selenium is a unique, disordered photosensing material in which carrier transport can be shifted entirely from localized to extended states where holes get hot, resulting in deterministic, non-Markovian impact ionization avalanche, causing selenium to exhibit characteristics similar to crystalline photoconductors. For the first time, we have fabricated a multiwell selenium detector using nanopillars that achieves both avalanche gain and unipolar time-differential charge sensing.