Search Results (41)

Background: Recent advances in single-photon emission computed tomography (SPECT) technology, particularly cadmium–zinc–telluride (CZT) detectors, have improved spatial resolution and contrast in cerebral blood flow imaging. This study aimed to investigate whether these improvements translate to enhanced diagnostic accuracy for Alzheimer’s disease (AD). Methods: We compared conventional SPECT (eCAM) with CZT SPECT in 29 patients (mean age 60.9 ± 17.6 years, 69% female) with suspected neurodegenerative diseases. Results: Gray matter/white matter contrast was significantly higher in CZT SPECT compared to eCAM (1.615 ± 0.096 vs. 1.458 ± 0.068, p < 0.001). However, diagnostic accuracy for AD did not improve with CZT SPECT. For the participating psychiatrist, sensitivity decreased from 0.750 (eCAM) to 0.625 (CZT), while for the radiologist, specificity dropped from 0.571 (eCAM) to 0.429 (CZT). Overall accuracy slightly decreased for both readers. Conclusions: These findings suggest that while CZT SPECT offers superior image quality, it may not immediately translate to improved diagnostic accuracy for AD. The study highlights the importance of specialized training for clinicians in interpreting higher-resolution CZT SPECT images to fully leverage their potential in neurodegenerative disease diagnosis. Future research should focus on developing standardized training protocols and larger, multi-center studies to validate these findings. Full article

Background: Left ventricular ejection fraction remains the primary focus in cardiac monitoring for oncology patients undergoing potentially cardiotoxic chemotherapy, while right ventricular function is seldom examined. This study evaluates how established risk factors for left ventricular dysfunction affect right ventricular function. Methods: This retrospective cohort study included 1770 patients undergoing cadmium–zinc–telluride equilibrium radionuclide angiocardiography before chemotherapy. Patients were categorized based on risk factors for left ventricular dysfunction—diabetes (DM), atrial fibrillation (AF), coronary heart disease (CHD), and previous oncological therapy—and compared to controls using independent t-tests. Results: Patients with previous oncological therapy exhibited a significantly lower right ventricular end-diastolic volume (RVEDV) (mean difference: −4.4 mL/m², 95% CI: −6.1 to −2.7, p < 0.001), lower right ventricular end-systolic volume (RVESV) (−2.3 mL/m², 95% CI: −3.4 to −1.2, p < 0.001), and lower right ventricular stroke volume (RVSV) (−2.1 mL/m², 95% CI: −3 to −1.2, p < 0.001). In patients with CHD, there was a higher right ventricular ejection fraction (RVEF) (3.0 mL/m², 95% CI: 0.8 to 5.2, p < 0.01), whereas patients with DM had lower RVEDV (−5.1 mL/m², 95% CI: −9.2 to −1, p < 0.05) and RVESV (−3.0 mL/m², 95% CI: −5.5 to −0.4, p < 0.05). No ventricular variables differed from the control group among patients with AF. Conclusions: Risk factors known to affect the left ventricle also impacted the right ventricle, with the exception of AF. Full article

Cadmium zinc telluride (CZT) detectors have the advantages of high detection efficiency and good energy resolution, which are widely used in the fields of X-ray detection, environmental monitoring and nuclear radiation detection. The Frisch grid structure is used more often in the preparation of detectors because of its good unipolarity and simple structure. In this paper, the effects of changing the gate position, width and relative dielectric constant on the electrical properties of Frisch grid CZT detectors, such as potential, weight potential, electric field distribution and charge collection efficiency, are simulated in detail by the finite element method. From the simulation results, the optimisation of the performance of the Frisch grid detector is mainly based on minimising the distance between the gate and anode within a reasonable interval, increasing the area of the Frisch grid and selecting a material with a high relative permittivity for the fabrication of the Frisch grid. The research work contributes to the development of CZT detectors. Full article

Background and Objectives: Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a well-established technique for evaluating myocardial perfusion and function in patients with suspected or known coronary artery disease. While conventional dual-detector SPECT scanners have limitations in spatial resolution and photon detection sensitivity, recent advancements, including full-ring solid-state cadmium zinc telluride (CZT) detectors, offer enhanced image quality and improved diagnostic accuracy. This study aimed to compare the performance of Veriton-CT, a full-ring CZT SPECT system, with GE Discovery 530c, a dedicated cardiac fixed-angle gamma camera, in myocardial perfusion imaging and their correlation with coronary angiography findings. Materials and Methods: This was a prospective study that analyzed 21 patients who underwent MPI at the Department of Nuclear Medicine, Lithuanian University of Health Sciences, Kauno Klinikos. A one-day stress–rest protocol using 99mTc-Sestamibi was employed, with stress testing performed via bicycle ergometry or pharmacological induction. MPI was first conducted using GE Discovery 530c (GE Health Care, Boston, MA, USA), followed by imaging on Veriton-CT, which included low-dose CT for attenuation correction. The summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) were analyzed and compared between both imaging modalities. Coronary angiography results were retrospectively collected, and lesion-based analysis was performed to assess the correlation between imaging results and the presence of significant coronary artery stenosis (≥35% and ≥70% narrowing). Image quality and the certainty of distinguishing the inferior myocardial wall from extracardiac structures were also evaluated by two independent researchers with differing levels of experience. Results: Among the 14 patients included in the final analysis, Veriton-CT was more likely to classify MPI scans as normal (64.3%) compared to GE Discovery 530c (28.6%). Additionally, Veriton-CT provided a better assessment of the right coronary artery (RCA) basin, showing greater agreement with coronary angiography findings than GE Discovery 530c, although the difference was not statistically significant. No significant differences in lesion overlap were observed for the left anterior descending artery (LAD) or left circumflex artery (LCx) basins. Furthermore, the image quality assessment revealed slightly better delineation of extracardiac structures using Veriton-CT (Spectrum Dynamics Medical, Caesarea, Israel), particularly when evaluated by an experienced researcher. However, no significant difference was observed when assessed by a less experienced observer. Conclusions: Our findings suggest that Veriton-CT, with its full-ring CZT detector system, may offer advantages over fixed-angle gamma cameras in improving image quality and reducing attenuation artifacts in MPI. Although the difference in correlations with coronary angiography findings was not statistically significant, Veriton-CT showed a trend toward better agreement, particularly in the RCA basin. These results indicate that full-ring SPECT imaging could improve the diagnostic accuracy of non-invasive MPI, potentially reducing the need for unnecessary invasive angiography. Further studies with larger patient cohorts are required to confirm these findings and evaluate the clinical impact of full-ring SPECT technology in myocardial perfusion imaging. Full article

Recently, the numerical simulation of solar cells has attracted tantamount scientific attention in the photovoltaic community because it saves on research time and resources before the actual fabrication of the devices in the laboratories. Despite significant advancements in the fabrication of quantum dot-sensitized solar cells (QDSSCs), the power conversion efficiency (PCE) is still low when compared to other solar cells such as perovskite. This efficiency gap poses a substantial challenge in harnessing the full potential of QDSSCs for widespread adoption in renewable energy applications. Enhancing the efficiency of QDSSCs is imperative for their commercial viability and widespread deployment. In this work, SCAPS-1D was used in the simulation of QDSSCs. The solar cell with a general configuration of FTO/TiO₂/PbS/HTL/Au was investigated. In the device, PbS quantum dots were inserted as the absorber layer, TiO₂ as the electron transport layer (ETL), gold as the back contact, and the following inorganic materials, i.e., copper (I) iodide (CuI), copper (I) oxide (Cu₂O), cadmium zinc telluride selenide (CZTSe), copper iron tin sulfide (CFTS), and copper zinc tin sulfide selenide (CZTSSe) were tested as HTL materials, and FTO acted as the conductive substrate. The best HTL material (CZTSSe) exhibited a PCE of 22.61%, with a fill factor (FF) of 84.67%, an open circuit voltage (V_oc) of 0.753 V, and a current density (J_sc) of 35.48 mA cm⁻². This study contributes to the field by employing SCAPS-1D simulations to optimize QDSSCs, exploring novel inorganic HTL materials for these solar cells and identifying CZTSSe as a promising low-cost HTL that significantly enhances both the performance and commercial viability of QDSSCs. Full article

Stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) require precise small-field dosimetry, verified through patient-specific quality assurance (PSQA). This study evaluated the feasibility of using a single-crystal cadmium–zinc–telluride (Cd_0.9Zn_0.1Te, CZT) detector for PSQA in SRS and SBRT. We fabricated a CZT detector with Au electrodes and examined its fundamental characteristics, including dose linearity, dose rate dependence, energy dependence, angular dependence, source-to-surface distance (SSD) dependence, field size dependence, depth dependence, and reproducibility, under 6 and 10 MV LINAC beam irradiation and compared the results with those from a standard ionization chamber. The results revealed that the CZT detector demonstrated excellent linearity across 0–1000 cGy with minimal deviation in the low-dose region, negligible dose rate dependence, and minimal energy dependence, exhibiting a 2.2% drop at 15 MV relative to 6 MV. Its angular and SSD dependencies deviated slightly from the ionization chamber, consistent with the expected physical behaviors and correctable in clinical practice. The detector also revealed consistent performance over time with excellent reproducibility, and its depth dependence results were consistent with those of the ionization chamber. Thus, the CZT detector provides consistent performance in small-field measurements under varying conditions, satisfying the requirements for SRS and SBRT. Full article

Background/Objectives: This study aimed to assess the diagnostic capability of quantitative parameters from whole-body bone single-photon emission computed tomography/computed tomography (SPECT/CT) in detecting bone metastases in prostate cancer patients; Methods: We retrospectively analyzed 82 prostate cancer patients who underwent staging bone scintigraphy with a full-ring 360° Cadmium-Zinc-Telluride (CZT) SPECT/CT system. From the SPECT/CT images, we measured the maximum (SUVmax) and mean (SUVmean) standardized uptake values at six normal bone sites (skull, humerus, thoracic spine, lumbar spine, iliac bone, and femur), and the SUVmax for both metastatic and benign bone lesions. Ratios of lesion SUVmax-to-maximum and mean uptake values at the skull, humerus, and femur were computed for each lesion; Results: SUVmax and SUVmean at the skull and femur exhibited significantly lower variance compared to those at the thoracic spine, lumbar spine, and iliac bone, and revealed no significant differences between patients with and without bone metastasis. In receiver operating characteristic curve analysis for detecting bone metastasis among 482 metastatic lesions, 132 benign bone lesions, and 477 normal bone sites, the lesion-to-femur mean uptake ratio demonstrated the highest area under the curve value (0.955) among SPECT/CT parameters. Using a cut-off value of 5.38, the lesion-to-femur mean uptake ratio achieved a sensitivity of 94.8% and a specificity of 86.5%; Conclusions: The bone lesion-to-femur mean uptake ratio was the most effective quantitative bone SPECT/CT parameter for detecting bone metastasis in prostate cancer patients. Quantitative analysis of bone SPECT/CT images could thus play a crucial role in diagnosing bone metastasis. Full article

The SIDDHARTA-2 collaboration has developed a novel X-ray detection system based on cadmium-zinc-telluride (CZT, CdZnTe), marking the first application of this technology at the DA$\Phi$NE electron-positron collider at INFN-LNF. This work aims to demonstrate the stability of the detectors’ performance in terms of linearity and resolution over short and long periods, thereby establishing their suitability for precise spectroscopic measurements within a collider environment. A reference calibration spectrum is presented in association with findings from assessments of linearity and resolution stability. Additionally, this study introduces a validated model of the response function of the detector. The relative deviations from the nominal values for the source transitions, obtained by fitting the entire spectrum with a background function and the previously introduced response function, are reported. Finally, a comparison of the calibration performance with and without beams circulating in the collider’s rings is presented. These promising results pave the way for applying CZT detectors in kaonic atom studies and, more generally, in particle and nuclear physics spectroscopy. Full article

Colloidal cadmium telluride (CdTe) nanoplatelets (NPLs) are promising materials for optoelectronic applications, such as photovoltaics and light-emitting diodes, due to their unique optical and electronic properties. However, controlling their growth, thickness, and stoichiometry remains challenging. This study explores the effect of synthesis temperature on the structural, optical, and stoichiometric properties of CdTe NPLs. CdTe NPLs were synthesized at temperatures of 170 °C, 180 °C, 190 °C, and 200 °C using colloidal methods. The resulting NPLs were characterized by UV–Vis absorption spectroscopy, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), and total reflection X-ray fluorescence (TXRF) to assess their morphology, structure, and elemental composition. The results showed that the synthesis temperature significantly affected the NPL’s morphology and stoichiometry. Optimal stoichiometry was achieved at 180 °C and 190 °C, with the crystal structure transitioning from zinc blende at lower temperatures to wurtzite at higher temperatures. Optical properties, including luminescence intensity and emission peaks, also varied with temperature. The synthesis temperature is an important parameter in controlling the structural and optical properties of CdTe NPLs. The optimal conditions for obtaining NPLs with the best characteristics were identified at 190 °C, presenting important findings for further optimization of CdTe NPL synthesis for optoelectronic applications. Full article

Single photon emission tomography/computed tomography (SPECT/CT) is a mature imaging technology with a dynamic role in the diagnosis and monitoring of a wide array of diseases. This paper reviews the technological advances, clinical impact, and future directions of SPECT and SPECT/CT imaging. The focus of this review is on signal amplifier devices, detector materials, camera head and collimator designs, image reconstruction techniques, and quantitative methods. Bulky photomultiplier tubes (PMTs) are being replaced by position-sensitive PMTs (PSPMTs), avalanche photodiodes (APDs), and silicon PMs to achieve higher detection efficiency and improved energy resolution and spatial resolution. Most recently, new SPECT cameras have been designed for cardiac imaging. The new design involves using specialised collimators in conjunction with conventional sodium iodide detectors (NaI(Tl)) or an L-shaped camera head, which utilises semiconductor detector materials such as CdZnTe (CZT: cadmium–zinc–telluride). The clinical benefits of the new design include shorter scanning times, improved image quality, enhanced patient comfort, reduced claustrophobic effects, and decreased overall size, particularly in specialised clinical centres. These noticeable improvements are also attributed to the implementation of resolution-recovery iterative reconstructions. Immense efforts have been made to establish SPECT and SPECT/CT imaging as quantitative tools by incorporating camera-specific modelling. Moreover, this review includes clinical examples in oncology, neurology, cardiology, musculoskeletal, and infection, demonstrating the impact of these advancements on clinical practice in radiology and molecular imaging departments. Full article

(1) Background: The objective of this study was to determine the optimal post-processing model for dynamic cadmium–zinc–telluride single-photon emission computed tomography (CZT-SPECT). (2) Methods: A total of 235 patients who underwent diagnostic invasive coronary angiography within three months of the SPECT and those who had coronary computed tomography angiography (CCTA) before SPECT (within 3 months) were enrolled in this study. Each SPECT study was processed to obtain global and regional stress myocardial blood flow (sMBF), rest-MBF (rMBF), myocardial flow reserve (MFR) and flow difference (FD) estimates obtained with 1-tissue-compartment (1TCM) and net retention (NR) modes, both with and without attenuation correction. (3) Results: The use of AC led to significantly higher sMBF, rMBF and DF values obtained by 1TCM compared those values derived by 1TCM with NAC; the lowest values of stress MBF and rest MBF were obtained by 1TCM_NAC. The resting flow, MFR and DF were significantly (p < 0.005) higher in the AC model than in NAC. All quantitative variables were significantly (p < 0.05) higher in NR_NAC than in the 1TC_NAC model. Finally, sMBF, rMBF and FD showed significantly (p < 0.05) higher values by using 1TMC_AC compared to NR_AC. (4) Conclusions: We suggested that 1-compartment and net retention models correctly reflect coronary microcirculation and can be used for clinical practice for evaluating quantitative myocardial perfusion by dynamic SPECT. Attenuation correction is an important step in post-processing dynamic SPECT data, which increases the consistency and diagnostic accuracy of models. Full article

Kaonic atom X-ray spectroscopy is a consolidated technique for investigations on the physics of strong kaon–nucleus/nucleon interaction. Several experiments have been conducted regarding the measurement of soft X-ray emission (<20 keV) from light kaonic atoms (hydrogen, deuterium, and helium). Currently, there have been new research activities within the framework of the SIDDHARTA-2 experiment and EXCALIBUR proposal focusing on performing precise and accurate measurements of hard X-rays (>20 keV) from intermediate kaonic atoms (carbon, aluminum, and sulfur). In this context, we investigated cadmium–zinc–telluride (CdZnTe or CZT) detectors, which have recently demonstrated high-resolution capabilities for hard X-ray and gamma-ray detection. A demonstrator prototype based on a new cadmium–zinc–telluride quasi-hemispherical detector and custom digital pulse processing electronics was developed. The detector covered a detection area of 1 cm² with a single readout channel and interesting room-temperature performance with energy resolution of 4.4% (2.6 keV), 3% (3.7 keV), and 1.4% (9.3 keV) FWHM at 59.5, 122.1, and 662 keV, respectively. The results from X-ray measurements at the DAΦNE collider at the INFN National Laboratories of Frascati (Italy) are also presented with particular attention to the effects and rejection of electromagnetic and hadronic background. Full article

Estimating accurate radiation doses when a radioactive source’s location is unknown can protect workers from radiation exposure. Unfortunately, depending on a detector’s shape and directional response variations, conventional G(E) function can be prone to inaccurate dose estimations. Therefore, this study estimated accurate radiation doses regardless of source distributions, using the multiple G(E) function groups (i.e., pixel-grouping G(E) functions) within a position-sensitive detector (PSD), which records the response position and energy inside the detector. Investigations revealed that, compared with the conventional G(E) function when source distributions are unknown, this study’s proposed pixel-grouping G(E) functions improved dose estimation accuracy by more than 1.5 times. Furthermore, although the conventional G(E) function produced substantially larger errors in certain directions or energy ranges, the proposed pixel-grouping G(E) functions estimate doses with more uniform errors at all directions and energies. Therefore, the proposed method estimates the dose with high accuracy and provides reliable results regardless of the location and energy of the source. Full article

The spectroscopic and imaging performance of energy-resolved photon counting detectors, based on new sub-millimetre boron oxide encapsulated vertical Bridgman cadmium zinc telluride linear arrays, are presented in this work. The activities are in the framework of the AVATAR X project, planning the development of X-ray scanners for contaminant detection in food industry. The detectors, characterized by high spatial (250 µm) and energy (<3 keV) resolution, allow spectral X-ray imaging with interesting image quality improvements. The effects of charge sharing and energy-resolved techniques on contrast-to-noise ratio (CNR) enhancements are investigated. The benefits of a new energy-resolved X-ray imaging approach, termed window-based energy selecting, in the detection of low- and high-density contaminants are also shown. Full article

Radiation detectors based on Cadmium Zinc Telluride (CZT) compounds are becoming popular solutions thanks to their high detection efficiency, room temperature operation, and to their reliability in compact detection systems for medical, astrophysical, or industrial applications. However, despite a huge effort to improve the technological process, CZT detectors’ full potential has not been completely exploited when both high spatial and energy resolution are required by the application, especially at low energies (<10 keV), limiting their application in energy-resolved photon counting (ERPC) systems. This gap can also be attributed to the lack of dedicated front-end electronics which can bring out the best in terms of detector spectroscopic performances. In this work, we present the latest results achieved in terms of energy resolution using SIRIO, a fast low-noise charge sensitive amplifier, and a linear-array pixel detector, based on boron oxide encapsulated vertical Bridgman-grown B-VB CZT crystals. The detector features a 0.25-mm pitch, a 1-mm thickness and is operated at a −700-V bias voltage. An equivalent noise charge of 39.2 el. r.m.s. (corresponding to 412 eV FWHM) was measured on the test pulser at 32 ns peaking time, leading to a raw resolution of 1.3% (782 eV FWHM) on the 59 keV line at room temperature (+20 °C) using an uncollimated ²⁴¹Am, largely improving the current state of the art for CZT-based detection systems at such short peaking times, and achieving an optimum resolution of 0.97% (576 eV FWHM) at 1 µs peaking time. The measured energy resolution at the 122 keV line and with 1 µs peaking time of a ⁵⁷Co raw uncollimated spectrum is 0.96% (1.17 keV). These activities are in the framework of an Italian collaboration on the development of energy-resolved X-ray scanners for material recycling, medical applications, and non-destructive testing in the food industry. Full article