Detector Technology Research Articles

Limited-angle TOF-PET for intraoperative surgical applications: proof of concept and first experimental data

The intraoperative gamma probe (IPG) based on single gamma-ray detection remains the current gold standard modality for sentinel lymph node identification and tumor removal in cancer patients. However, IPGs do not meet the <5% false negative rate (FNR) requirement, a key metric suggested by the American Society of Clinical Oncology (ASCO). We aim to reduce FNR by using time of flight (TOF) PET detector technology in limited angle geometry system by using only two detector panels in coincidence. For proof of concept, we used two Hamamatsu TOF PET detector modules (C13500-4075YC-12) featuring 12× 12 arrays of 4.14× 4.14× 20 mm3 LFS crystal pixels with 4.2 mm pitch and coupled one-one to silicon photomultiplier (SiPM) pixels. The measured detector coincidence timing resolution (CTR) was 271 ps FWHM for the whole detector. We 3D printed lesion phantom containing spheres 2–10 mm in diameter, representing lymph nodes, and placed it inside a 10-liter warm background water phantom. Experimental results showed that with subminute data acquisition, 6 mm diameter spheres could be identified in the image when a lesion phantom with a 10:1 activity ratio to background was used. The simulation results were in good agreement with the experimental data by resolving 6 mm diameter spherical lesions with a 60 second acquisition time in a 25 cm deep background water phantom with a 10:1 activity ratio. As expected, the image quality improved as the CTR improved in the simulation and with decreasing background water phantom depth or increasing lesion-to-background activity ratio in the experiment. With the results presented here, we concluded that using a limited angle TOF PET detector system is a major step forward for intraoperative applications in that lesion detectability is beyond what conventional gamma- and NIR-based probes could achieve.

First GEM measurements at WEST and perspectives for fast electrons and heavy impurities transport studies in tokamaks

Soft X-ray (SXR) radiation emitted from tokamak plasmas contains very useful information about plasma stability, shape and impurity content, all key parameters to improve plasma performance. In the deuterium-tritium phase of ITER, the high neutron fluxes, gamma and hard X-ray emission will constitute too harsh an environment to permit the use of classical semiconductor detectors. New SXR detector technologies, more robust to such environments, should thus be investigated. First GEM (Gas Electron Multiplier) measurements performed at WEST were successful and showed that both spatially and spectrally resolved calibrated data could be acquired. Strategies to reconstruct tungsten (W) impurity radiation synthetic diagnostics, modelling and real measurements based on multiple diagnostics are proposed.

Light yield and field dependence measurement in PandaX-II dual-phase xenon detector

The dual-phase xenon time projection chamber (TPC) is one of the most sensitive detector technology for dark matter direct search, where the energy deposition of incoming particle can be converted into photons and electrons through xenon excitation and ionization. The detector response to signal energy deposition varies significantly with the electric field in liquid xenon. We study the detector's light yield and its dependence on the electric field in the PandaX-II dual-phase detector containing 580 kg liquid xenon in the sensitive volume. From our measurements, the light yield at electric fields from 0 V/cm to 317 V/cm is obtained for energy depositions up to 236 keV.

Calorimetric classification of track-like signatures in liquid argon TPCs using MicroBooNE data

The MicroBooNE liquid argon time projection chamber located at Fermilab is a neutrino experiment dedicated to the study of short-baseline oscillations, the measurements of neutrino cross sections in liquid argon, and to the research and development of this novel detector technology. Accurate and precise measurements of calorimetry are essential to the event reconstruction and are achieved by leveraging the TPC to measure deposited energy per unit length along the particle trajectory, with mm resolution. We describe the non-uniform calorimetric reconstruction performance in the detector, showing dependence on the angle of the particle trajectory. Such non-uniform reconstruction directly affects the performance of the particle identification algorithms which infer particle type from calorimetric measurements. This work presents a new particle identification method which accounts for and effectively addresses such non-uniformity. The newly developed method shows improved performance compared to previous algorithms, illustrated by a 93.7% proton selection efficiency and a 10% muon mis-identification rate, with a fairly loose selection of tracks performed on beam data. The performance is further demonstrated by identifying exclusive final states in νμCC interactions. While developed using MicroBooNE data and simulation, this method is easily applicable to future LArTPC experiments, such as SBND, ICARUS, and DUNE.

BraggNN: fast X-ray Bragg peak analysis using deep learning.

X-ray diffraction based microscopy techniques such as high-energy diffraction microscopy (HEDM) rely on knowledge of the position of diffraction peaks with high precision. These positions are typically computed by fitting the observed intensities in detector data to a theoretical peak shape such as pseudo-Voigt. As experiments become more complex and detector technologies evolve, the computational cost of such peak-shape fitting becomes the biggest hurdle to the rapid analysis required for real-time feedback in experiments. To this end, we propose BraggNN, a deep-learning based method that can determine peak positions much more rapidly than conventional pseudo-Voigt peak fitting. When applied to a test dataset, peak center-of-mass positions obtained from BraggNN deviate less than 0.29 and 0.57 pixels for 75 and 95% of the peaks, respectively, from positions obtained using conventional pseudo-Voigt fitting (Euclidean distance). When applied to a real experimental dataset and using grain positions from near-field HEDM reconstruction as ground-truth, grain positions using BraggNN result in 15% smaller errors compared with those calculated using pseudo-Voigt. Recent advances in deep-learning method implementations and special-purpose model inference accelerators allow BraggNN to deliver enormous performance improvements relative to the conventional method, running, for example, more than 200 times faster on a consumer-class GPU card with out-of-the-box software.

New Radionuclides and Technological Advances in SPECT and PET Scanners.

Simple SummaryAdvances in nuclear medicine are made by technological and radionuclide improvements. Throughout nuclear medicine’s history, these advances were often intertwined and complementary based on different clinical questions, availability and need. This paper covers some of these developments in radionuclides and instrumentation.Developments throughout the history of nuclear medicine have involved improvements in both instrumentation and radionuclides, which have been intertwined. Instrumentation developments always occurred during the search to improving devices’ sensitivity and included advances in detector technology (with the introduction of cadmium zinc telluride and digital Positron Emission Tomography—PET-devices with silicon photomultipliers), design (total body PET) and configuration (ring-shaped, Single-Photon Emission Computed Tomography (SPECT), Compton camera). In the field of radionuclide development, we observed the continual changing of clinically used radionuclides, which is sometimes influenced by instrumentation technology but also driven by availability, patient safety and clinical questions. Some areas, such as tumour imaging, have faced challenges when changing radionuclides based on availability, when this produced undesirable clinical findings with the introduction of unclear focal uptakes and unspecific uptakes. On the other end of spectrum, further developments of PET technology have seen a resurgence in its use in nuclear cardiology, with rubidium-82 from strontium-82/rubidium-82 generators being the radionuclide of choice, moving away from SPECT nuclides thallium-201 and technetium-99m. These continuing improvements in both instrumentation and radionuclide development have helped the growth of nuclear medicine and its importance in the ever-evolving range of patient care options.

The large inner Micromegas modules for the Atlas Muon Spectrometer upgrade: Construction, quality control and characterization

The steadily increasing luminosity of the LHC requires an upgrade with high-rate and high-resolution detector technology for the inner end cap of the ATLAS muon spectrometer: the New Small Wheels (NSW). In order to achieve the goal of precision tracking at a hit rate of about 15 kHz/cm2 at the inner radius of the NSW, large area Micromegas quadruplets with 100µm spatial resolution per plane have been produced. IRFU, from the CEA research center of Saclay, is responsible for the production and validation of LM1 Micromegas modules. The construction, production, qualification and validation of the largest Micromegas detectors ever built are reported here. Performance results under cosmic muon characterization will also be discussed.

P61 - Metal oxide field effect transistors (MOSFETs) versus optically stimulated luminescence detectors (OSLDs) technology in total body irradiation

P61 - Metal oxide field effect transistors (MOSFETs) versus optically stimulated luminescence detectors (OSLDs) technology in total body irradiation

Characterization of FBK 3D pixel sensor modules based on RD53A readout chip for the ATLAS ITk

CERN is planning to upgrade its Large Hadron Collider to the High Luminosity phase (HL-LHC), pushing detector technologies to cope with unprecedently demanding performance in terms of particle rate and radiation hardness. The ATLAS experiment decided to equip the innermost layer (L0) of its Inner Tracker (ITk) with small-pitch 3D pixels of two different geometries, i.e., 25 µm × 100 µm for the central barrel and 50 µm × 50 µm for the lateral rings. A new generation of 3D pixels featuring these small-pitch dimensions and reduced active thickness (∼150 µm) has been developed to this purpose within a collaboration of INFN and FBK since 2014. Recently, the R&D activities have been focused on the characterization of modules based on sensors compatible with the RD53A readout chip, which were tested in laboratory and at beam lines. In this paper, we report on the characterization of modules irradiated with protons up to a fluence of 1 × 1016 neq/cm2, including threshold tuning and noise measurements, and results from beam tests performed at DESY. Moreover, we will discuss about the electrical characteristics at wafer level and at module level before and after irradiation.

Sensor Design Optimization of Innovative Low-Power, Large Area FD-MAPS for HEP and Applied Science

Fully depleted monolithic active pixel sensors (FD-MAPSs) represent a state-of-the-art detector technology and profit from a low material budget and cost for high-energy physics experiments and other fields of research like medical imaging and astro-particle physics. Compared to the MAPS currently in use, fully depleted pixel sensors have the advantage of charge collection by drift, which enables a fast and uniform response overall to the pixel matrix. The functionality of these devices has been shown in previous proof-of-concept productions. In this article, we describe the optimization of the test pixel designs that will be implemented in the first engineering run of the demonstrator chip of the ARCADIA project. These optimization procedures include radiation damage models that have been employed in Technology Computer Aided Design simulations to predict the sensors’ behavior in different working environments.

Ultra Fast Astronomy: Optimized Detection of Multimessenger Transients

Ultra Fast Astronomy is a new frontier becoming enabled by improved detector technology allowing discovery of optical transients on millisecond to nanosecond time scales. These may reveal counterparts of energetic processes such as fast radio bursts, gamma ray bursts, gravitational wave events, or play a role in the optical search for extraterrestrial intelligence (oSETI). We explore some example science cases and their optimization under constrained resources, basically how to distribute observations along the spectrum of short duration searches of many targets or long searches over fewer targets. As a demonstration of the method we present some analytic and some numerical optimizations, of both raw detections and science characterization such as an information matrix analysis of constraining a burst delay -- flash duration relation.

A Brief Overview of Scanning Transmission Electron Microscopy in a Scanning Electron Microscope

Abstract This article provides a brief overview of STEM-in-SEM, discussing the pros and cons, recent advancements in detector technology, and the emergence of 4D STEM-in-SEM, a relatively new method that uses diffraction patterns recorded at different raster positions to enhance images offline in selected regions of interest.

Evaluation of diffusion coefficient of P-glycoprotein molecules labeled with green fluorescent protein in living cell membrane.

The movement of individual molecules inside living cells has recently been resolved by single particles tracking (SPT) method which is a powerful tool for probing the organization and dynamics of the plasma membrane constituents. Effective treatment of metastatic cancers requires the toxic chemotherapy, however this therapy leads to the multidrug resistance phenomenon of the cancer cells, in which the cancer cells resist simultaneously to different drugs with different targets and chemical structures. P-glycoprotein molecules which are responsible for multidrug resistance of many cancer cells have been studied by cancer biologists during past haft of century. Recently, advances in laser and detector technologies have enabled single fluorophores to be visualized in aqueous solution. The development of the total internal reflection fluorescent microscope (TIRFM) provided means to monitor dynamic molecular localization in living cells. In this paper, P-glycoproteins (PGP) were labeled with green fluorescent protein (GFP) in living cell membrane of Madin-Darby canine kidney (MDCK) and the TIRFM method was used to characterize the dynamics of individual protein molecules on the surface of living cells. An evanescent field was produced by a totally internally reflected and a laser beam was illuminated the glass-water interface. GFP-PGP proteins that entered the evanescent field appeared as individual spots of light which were slighter than background fluorescence. We obtained high-resolution images and diffusion maps of membrane proteins on cell surface and showed the local diffusion properties of specific proteins on single cells. We also determined the diffusion coefficient, the mean square displacement and the average velocity of the tracked particles, as well as the heterogeneity of the cell environment. This study enabled us to understand single-molecule features in living cell and measure the diffusion kinetics of membrane-bound molecules.

Is Endogenous Ethylene Production Associated with Increased Shoot Number in Gentian Cultured In Vitro? Developing a Method for Ethylene Measurement at Nano Level within a Gas-exchangeable In Vitro System

We investigated the possibility of either exogenous ethylene or endogenous ethylene production having an association with the increase in shoot number when nodal explants of Gentiana spp. ‘Little Pinkie’ were cultured in an in vitro medium supplemented with ethephon (10 mg⋅L–1). For the first time within an in vitro system, we report the application of laser ethylene detector technology, and optimization of the methodology to quantify concentrations of ethylene (in the part-per-billion range) released from ethephon decomposition within the atmosphere of gas-exchangeable culture vessels including nodal explants. Compared with continuous (continuous measurements on the same replicate of vessels) and repeated (sampling same replicate of vessels every 48 hours) sampling methodologies, the nonrepeated (sampling fresh replicate of vessels every 48 hours) method of measurement of ethylene concentration was more representative of the actual condition within vessels. Although no prior published data exist showing the positive or negative effect of gaseous ethylene in the headspace of culture vessels on bud outgrowth in gentian, our study shows gaseous ethylene in the headspace of culture vessels was not effective in increasing shoot formation in gentian explants cultured in vitro, whereas ethephon supplementation in agar was effective. Plant material in culture vessels did not have a significant effect on ethylene production regardless of the presence or absence of ethephon. Therefore, although ethephon supplementation in the medium produced gaseous ethylene in the headspace, it was unlikely to cause endogenous ethylene production in explants, but it did trigger shoot formation in ‘Little Pinkie’, perhaps through decomposition to ethylene within the explant tissue, enhancing the internal ethylene level possibly at a locally high concentration.

Medipix3 for dosimetry and real-time beam monitoring: first tests at a 60 MeV proton therapy facility

Charged particle therapy (CPT) is an advanced modality of radiation therapy which has grown rapidly worldwide, driven by recent developments in technology and methods of delivery. To ensure safe and high quality treatments, various instruments are used for a range of different measurements such as for quality assurance, monitoring and dosimetry purposes. With the emergence of new and enhanced delivery techniques, systems with improved capabilities are needed to exceed existing performance limitations of conventional tools. The Medipix3 is a hybrid pixel detector able to count individual protons with millisecond time resolution at clinical flux with near instant readout and count rate linearity. The system has previously demonstrated use in medical and other applications, showing wide versatility and potential for particle therapy. In this work we present measurements of the Medipix3 detector in the 60 MeV ocular proton therapy beamline at the Clatterbridge Cancer Centre, U.K. The beam current and lateral beam profiles were evaluated at multiple positions in the treatment line and compared with EBT3 Gafchromic film. The recorded count rate linearity and temporal analysis of the beam structure was measured with Medipix3 across the full range of available beam intensities, up to 3.12 × 1010 protons/s. We explore the capacity of Medipix3 to provide non-reference measurements and its applicability as a tool for dosimetry and beam monitoring for CPT. This is the first known time the performance of the Medipix3 detector technology has been tested within a clinical, high proton flux environment.

Diagnostic protocols in oncology: workup and treatment planning. Part 1: the optimitation of CT protocol.

The increase in oncology knowledge and the possibility of creating personalized medicine by selecting a more suitable therapy related to tumor subtypes, as well as the patient's management with cancer within a multidisciplinary team has improved the clinical outcomes. Early detection of cancer through screening-based imaging is probably the major contributor to a reduction in mortality for certain cancers. Nowadays, imaging can also characterize several lesions and predict their histopathological features and can predict tumor behaviour and prognosis. CT is the main diagnostic tool in oncologic imaging and is widely used for the tumors detection, staging, and follow-up. Moreover, since CT accounts for 49-66% of overall patient radiation exposure, the constant reduction, optimization, dose inter- and intraindividual consistency are major goals in radiological field. In the recent years, numerous dose reduction techniques have been established and created voltage modulation keeping a satisfactory image quality. The introduction of CT dual-layer detector technology enabled the acquisition of spectral data without additional CT x-ray tube or additional acquisitions. In addition, since MRI does not expose the body to radiation, it has become a mainstay of non-invasive diagnostic radiology modality since the 1980s.

The Detector Control System for the magnetic field sensors in New Small Wheel phase I upgrade of ATLAS detector

In conjunction with the High Luminosity upgrade of the Large Hadron Collider accelerator at CERN, the ATLAS detector is also undergoing an upgrade to handle the significantly higher data rates. The muon end-cap system upgrade in ATLAS, lies with the replacement of the Small Wheel. The New Small Wheel (NSW) is expected to combine high tracking precision with upgraded information for the Level-1 trigger. To accomplish this, small Thin Gap Chamber (sTGC) and MicroMegas detector technologies are being deployed. Due to their installation location in ATLAS, the effects of Barrel Toroid and End-Cap Toroid magnets on NSW must be measured. For the final experiment at ATLAS, each sTGC large double wedge will be equipped with magnetic field Hall effect sensors to monitor the magnetic field near the NSW. The readout is done with an Embedded Local Monitor Board (ELMB) called MDT DCS Module (MDM). For the integration of this hardware in the experiment, first, a detector control system was developed to test the functionality of all sensors before their installation on the detectors. Subsequently, another detector control system was developed for the commissioning of the sensors. Finally, a detector control system based on the above two is under development for the expert panels of ATLAS experiment. In this paper, the sensor readout, the connectivity mapping and the detector control systems will be presented.

Full Detector Simulation with Unprecedented Background Occupancy at a Muon Collider

In recent years, a Muon collider has attracted a lot of interest in the high-energy physics community, thanks to its ability of achieving clean interaction signatures at multi-TeV collision energies in the most cost-effective way. Estimation of the physics potential of such an experiment must take into account the impact of beam-induced background on the detector performance, which has to be carefully evaluated using full detector simulation. Tracing of all the background particles entering the detector region in a single bunch crossing is out of reach for any realistic computing facility due to the unprecedented number of such particles. To make it feasible a number of optimisations have been applied to the detector simulation workflow. This contribution presents an overview of the main characteristics of the beam-induced background at a Muon collider, the detector technologies considered for the experiment and how they are taken into account to strongly reduce the number of irrelevant computations performed during the detector simulation. Special attention is dedicated to the optimisation of track reconstruction with the conformal tracking algorithm in this high-occupancy environment, which is the most computationally demanding part of event reconstruction.

Reduction of radiation exposure in scoliosis monitoring using flat detector and pulsed fluoroscopy technology

A new flat detector and pulsed fluoroscopy technology is available to further reduce radiation exposure in radiological monitoring during scoliosis treatment in children and adolescents. The aim of this study is to compare different settings of the system (opening area(OA) and image quality settings (IQS)) in order to find the optimal parameters with high image quality and the lowest possible radiation exposure. Therefore, we examined four cadaver spines (T1 to sacrum) with the flat detector technique using digital pulsed fluoroscopy and simulated the abdominal soft tissues. The images were merged and evaluated by three different investigators using an established scoring system. For comparison, we used digital radiography images of the cadaver spines. The values for the DAP increased from the small OA (33% ; 0.56 µGy·m²) to the maximum OA (100% ; 0.82 µGy·m²) by 45% (p = .003) and from the low image quality setting (0.57 µGy·m²) to the high setting (0.84 µGy·m²) by 48% (p = .028). Despite the low DAP, the setting 33% OA achieved the best point values for image quality, therefore this setting is clearly preferred. Using a digital fluoroscopy system allows a significant reduction of radiation exposure by a factor of 7.5 (3.88µGy·m² to 0.5µGy·m²) compared to slot- scanning x-ray (EOS). Due to this success, the flat detector and pulsed fluoroscopy technology can be an alternative to established methods such as X-ray and EOS in clinical use.

A feasibility study of time of flight cone beam computed tomography imaging.

The time of flight (TOF) cone beam computed tomography (CBCT) was recently shown to reduce the X-ray scattering effects by 95% and improve the image CNR by 110% for large volume objects. The advancements in X-ray sources like in compact Free Electron Lasers (FEL) and advancements in detector technology show potential for the TOF method to be feasible in CBCT when imaging large objects. To investigate the feasibility and efficacy of TOF CBCT in imaging smaller objects with different targets such as bones and tumors embedded inside the background. The TOF method used in this work was verified using a 24 cm phantom. Then, the GATE software was used to simulate the CBCT imaging of an 8 cm diameter cylindrical water phantom with two bone targets using a modeled 20 keV quasi-energetic FEL source and various TOF resolutions ranging from 1 to 1000 ps. An inhomogeneous breast phantom of similar size with tumor targets was also imaged using the same system setup. The same results were obtained in the 24 cm phantom, which validated the applied CBCT simulation approach. For the case of 8 cm cylindrical phantom and bone target, a TOF resolution of 10 ps improved the image contrast-to-noise ratio (CNR) by 57% and reduced the scatter-to-primary ratio (SPR) by 8.63. For the case of breast phantom and tumor target, image CNR was enhanced by 12% and SPR was reduced by 1.35 at 5 ps temporal resolution. This study indicates that a TOF resolution below 10 ps is required to observe notable enhancements in the image quality and scatter reduction for small objects around 8 cm in diameter. The strong scattering targets such as bone can result in substantial improvements by using TOF CBCT.