Search

Local failure remains the major concern in grade 4 glioma or glioblastoma (GBM). Pilot studies have shown a radiotherapy (RT) dose–response relationship in GBM. Here we present our preliminary data of RT dose escalation using 68Ga-Pentixafor PET scan. High 68Ga-pentixafor uptake in glioma cells helps in sharp demarcation between tumour and normal brain. This phase II prospective study was conducted from 2018 to 2020. Thirty, biopsy-proven cases of grade 4 glioma were included. All patients underwent post-operative MRI of the brain and 68Ga-Pentixafor PET scan. RT was planned in 2-phases. Phase-1 GTV (GTV1) comprised of T2/flair abnormality, PET-avid disease and post-op cavity. A margin of 2cm was given to GTV-1 to create phase-1 CTV (CTV1), which was further expanded to 0.5cm to generate phase-1 PTV (PTV1). A radiation dose of 46Gy/23fr was prescribed to PTV-1. Phase-2 GTV (GTV2) consisted of CT/MRI contrast-enhancing lesion, PET avid disease and post-op cavity. A margin of 0.5 cm was given to GTV2 to create phase-2 CTV (CTV2) which was expanded to 0.5 cm to create phase-2 PTV (PTV2). RT dose of 14 Gy/7 fr was prescribed to PTV2. PET avid disease was delineated as GTV PET and a margin of 3mm was given to generate PTV-PET which received escalated RT dose of 21 Gy/7fr by simultaneous integrated boost (SIB) in phase 2 (Total dose to PTV PET = 67 Gy/30 fr). All patients received concurrent and adjuvant temozolomide. The data was prospectively maintained in Microsoft Excel sheet. SPSS v 23 was used for statistical analysis. The primary endpoints were estimation of the overall survival (OS) and progression-free survival (PFS), and secondary endpoint was to measure the incidence of radiation necrosis. Categorical variables were reported as frequency and percentage and quantitative variables were reported as median and range. Data from thirty patients were analysed. A median OS of 23 months was observed with estimated 1, 2 and 3 years OS of 90%, 40% and 17.8% respectively. A significant association of OS was seen with the extent of surgery (p = 0.04) and kernofsky performance status (p = 0.007). No patient developed significant radiation necrosis. The index study did not show any survival benefit from dose escalation RT. However, all of the patients tolerated the treatment well and none of them developed radiation necrosis. Considering the small sample size as a limitation of the index study, the role of 68Ga-pentixafor PET scan for radiation dose escalation should be further explored. CTRI/2019/05/019146. • Radiotherapy dose escalation in grade 4 glioma using 68Ga-Pentixafor PET scan. • Increased RT dose (67Gy/30#/6 weeks) was used for PET avid lesion. • None of the patients developed radiation necrosis. • No survival benefit from RT dose escalation. • Limitation – Small sample size. [ABSTRACT FROM AUTHOR]

Purpose Since the 1990s, PET has been successfully combined with MR or CT systems. In the past years, especially PET systems have seen a trend towards an enlarged axial field of view (FOV), up to a factor of ten. Methods Conducting a thorough literature research, we summarize the status quo of contemporary total-body (TB) PET/CT scanners and give an outlook on possible future developments. Results Currently, three human TB PET/CT systems have been developed: The PennPET Explorer, the uExplorer, and the Biograph Vision Quadra realize aFOVs between 1 and 2 m and show a tremendous increase in system sensitivity related to their longer gantries. Conclusion The increased system sensitivity paves the way for short-term, low-dose, and dynamic TB imaging as well as new examination methods in almost all areas of imaging. [ABSTRACT FROM AUTHOR]

Rationale and objectives: The purpose of this study was to evaluate the feasibility of unconstrained three-material decomposition in a human tissue specimen containing iodinated contrast agent, using an experimental multi-bin photon-counting silicon detector. It was further to evaluate potential added clinical value compared to a 1st-generation state-of-the-art dual-energy computed tomography system. Materials and methods: A prototype photon-counting silicon detector in a bench-top setup for x-ray tomographic imaging was calibrated using a multi-material calibration phantom. A heart with calcified plaque was obtained from a deceased patient, and the coronary arteries were injected with an iodinated contrast agent mixed with gelatin. The heart was imaged in the experimental setup and on a 1st-generation state-of-the-art dual-energy computed tomography system. Projection-based three-material decomposition without any constraints was performed with the photon-counting detector data, and the resulting images were compared with those obtained from the dual-energy system. Results: The photon-counting detector images show better separation of iodine and calcium compared to the dual-energy images. Additional experiments confirmed that unbiased estimates of soft tissue, calcium, and iodine could be achieved without any constraints. Conclusion: The proposed experimental system could provide added clinical value compared to current dual-energy systems for imaging tasks where mix-up of iodine and calcium is an issue, and the anatomy is sufficiently small to allow iodine to be differentiated from calcium. Considering its previously shown count rate capability, these results show promise for future integration of this detector in a clinical CT scanner. Key Points: • Spectral photon-counting detectors can solve some of the fundamental problems with conventional single-energy CT. • Dual-energy methods can be used to differentiate iodine and calcium, but to do so must rely on constraints, since solving for three unknowns with only two measurements is not possible. Photon-counting detectors can improve upon these methods by allowing unconstrained three-material decomposition. • A prototype photon-counting silicon detector with high count rate capability allows performing unconstrained three-material decomposition and qualitatively shows better differentiation of iodine and calcium than dual-energy CT. [ABSTRACT FROM AUTHOR]

Purpose: Online dose verification based on proton‐induced positron emitters is a promising strategy for quality assurance in proton therapy. Because of the nonlinear correlation between dose and the activity distributions, a machine learning‐based approach was developed to establish their relationship. Methods: Simulations were carried out using a pencil beam scanning system and a computed tomography (CT) image‐based phantom. A DiscoGAN model was developed to perform dose verification for both central and off‐center lines. Besides the activity as input, HU information from CT images and stopping power (SP) prior were incorporated as auxiliary features for the model. The performance was quantitatively studied in terms of mean absolute error (MAE) and mean relative error (MRE), under different signal‐to‐noise ratios (SNRs). In addition to a dataset comprising monoenergetic beams, two additional datasets were generated to evaluate the model's generalization capability: five reconstructed PET images based on an in‐beam PET system and a dataset comprising spread‐out Bragg peaks (SOBPs). Results: The feasibility of dose verification was successfully demonstrated for all three datasets. For the monoenergetic case (i.e., raw activity of positron emitters), the MRE is found to be <1% for the central lines and 5% for the off‐center lines, respectively. The range uncertainty is found to be less than 1 mm. The prediction based on five PET images, which take into account the detection of 511‐keV photons and image reconstruction, yields slightly inferior performance. For the SOBP case, the MRE of the center lines is found to be <3% and the range uncertainty is <1 mm. The inclusion of anatomical information (HU and SP) improves both accuracy and generalization of the DiscoGAN model. Conclusion: The combination of proton‐induced positron emitters, in‐beam PET, and machine learning may become a useful tool allowing for patient‐specific online dose verification in proton therapy. [ABSTRACT FROM AUTHOR]

Objectives: Single-photon emission computed tomography/computed tomography (SPECT/CT) hybrid systems have the advantage of performing various scans using the same imaging setting. Absorption and scattering of the gamma rays by the patient's body significantly affect images obtained from scintigraphy, especially in myocardial perfusion imaging. An important parameter for image quality in SPECT is image contrast which is defined as the difference in density between regions of the image corresponding to different levels of radioactive uptake in the patient. We objective of the study was to evaluate the influence of applying different correction methods on image contrast of myocardial SPECT/CT images. Material and Methods: A total of 114 patients, 43 females and 71 males, patient's raw data were processed and analyzed using attenuation correction (AC), scatter correction (SC), both attenuation and scatter correction together (ACSC), and no correction (NC). We short axis (coronal) slices resulted from the raw data reconstruction were chosen to perform the processing for hot and cold spheres for contrast values measurement. Statistical analysis was made for the measured contrast values for AC, SC, ACSC, and NC to determine the best image contrast. Results: When applying SC alone, it yields better contrast value (0.834), compared to AC (0.677) and ACSC (0.739). Both ACSC and AC had better image contrast compared to NC (0.592). Conclusion: We intercomparison study between the correction conditions indicates that the counts in SPECT/ CT are highly affected by all correction methods. We image contrast has been significantly improved by using SC, AC, and ACSC when compared with the NC image. Furthermore, SC is superior in the image contrast than the other correction conditions in the reconstruction of SPECT/CT MPI. [ABSTRACT FROM AUTHOR]

Computed tomography using X‐rays is applied during the bulk growth of silicon carbide (SiC) to investigate growth kinetics in situ during the physical vapor transport process. In addition to the standard SiC source material, in particular, a pure solid source SiC block is used. It is found that the growth rate is lowered as the sublimation of gaseous species is limited to the top part of the solid source. The morphological changes in the source area during growth differ significantly compared with the process when conventional powder is used. The formation of multiple growth centers on the surface of the seed is monitored in situ with a computed tomography system. In a series of experiments, the influence of the supersaturation on the growth is examined. The in situ computed tomography shows that the curvature of the growth interface is stronger influenced by the thermal field at higher pressures. A high supersaturation leads to the formation of rather smooth surface morphologies, whereas the formation of large steps on the surface is induced at lower supersaturations. [ABSTRACT FROM AUTHOR]

Trauma is one of the most important issues of most healthcare systems accompanying with head trauma in the most cases. We sought to determine the scoring system and initial Computed Tomography (CT) findings predicting the death at hospital discharge (early death) in patients with traumatic brain injury based on Marshall and Rotterdam CT scores. This is a cross sectional study on traumatic neurosurgical patients with mild-to-severe traumatic brain injury admitted to the emergency department of neurosurgery shyam shah medical college,rewa. Patients≥18 years old with TBI during last 24 hours with GCS≤13 were included and exclusion criteria were multiple trauma, penetrating injuries, previous history of anticoagulant therapy, pregnancy, not willingness for participation. Their initial CT and status at hospital discharge, one and three months (dead or alive) were reviewed, and both CT scores were calculated. We examined whether each score is related to death using SPSS11 by The Mann–Whitney U at the level of p≤0.05. Overall, 98 patients were included. Mean age was 43.52±21.29. Most patients were male (63.3%). Mean Marshall and Rotterdam CT scores were 3.2±1.3 and 2.5±1. The mortality at two weeks, one moth and three months were 19.4%, 20.4%, and 20.4%. Rotterdam CT score was significantly different based on type of hematoma. Median GCS score in alive and dead patients on 2 weeks were 10 and 4 (p=0.0001), at one month were 10 and 4 (p=0.0001), and at three months were 10 and 4 (p=0.0001). The median Marshall CT score on 2 weeks were 2 and 4 (p=0.0001), at one month were 2 and 4 (p=0.0001), and at three months were 2 and 4 (p=0.0001). The median Rotterdam CT score on 2 weeks were 2 and 4 (p=0.0001), at one month were 2 and 3 (p=0.001), and at three months were 2 and 3 (p=0.001). The Rotterdam CT score was significantly correlated with mortality at two weeks, one month and three months (p=0.004, p=0.001, and p=0.001, respectively). The Marshall CT score was not significantly correlated with mortality at any time. The Rotterdam CT score was more accurate for prediction of mortality on 2 weeks (ROC80.9), at one month (ROC80.7), and at three months were (ROC80.7) than The Rotterdam CT score (ROC 76, 74.1, and 74.1, respectively). This study concluded that The Marshall CT score was more accurate for prediction of mortality on 2 weeks, at one month, and at three months were than The Marshall CT score with higher ROC. The correlation of the Rotterdam CT score with mortality was significant. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) are useful for radiotherapy. Currently, efforts are underway globally for the development of novel titanium dioxide NPs (TiO2-NPs) that exhibit both contrast effects and anti-tumor effects. In this study, the image contrast properties of TiO2-NPs were evaluated using a clinical magnetic resonance imaging (MRI) system and a clinical computed tomography (CT) scanner, as the use of TiO2-NPs as an anti-cancer agent has been reported in several reports. An obvious difference in visualization was observed between the control and TiO2-NP samples on T2-weighted images. These results suggest that TiO2 can potentially be used as a novel theranostic drug with radiosensitizing ability and radiological diagnostic ability, through modification of chemical groups on its surface, and as a component of drug delivery systems. [ABSTRACT FROM AUTHOR]

Purpose: For cone‐beam computed tomography (CBCT) systems, we propose a sphere phantom based method to estimate the full three‐dimensional (3D) modulation transfer function (MTF). Methods: The FDK reconstruction of CBCT system in a local region was modeled by a triple convolution operator. Afterward, we calculated the directional projections of ideal and reconstructed sphere phantoms into a two‐dimensional (2D) plane for multiple views. To estimate the projected 3D point spread function (PSF), we applied the 2D Richardson–Lucy deconvolution with Tikhonov–Miller (RL‐TM). After estimating the projected 3D PSF from multiple views, the full 3D PSF was estimated by performing filtered backprojection. Then, the full 3D MTF was calculated by taking the modulus of the Fourier transform of the estimated 3D PSF. To validate the proposed method, we reconstructed sphere phantoms from simulation and experiment data. We simulated ideal 3D MTFs and compared them with the estimated 3D MTFs along the fz‐, fx‐, and f45∘‐directions. The full‐width at half‐maximum (FWHM) and full‐width at tenth‐maximum (FWTM) values were compared between ideal and estimated 3D MTFs. Results: The estimated 3D MTFs from both the simulation and experiment results show qualitative similarity in their shapes with the ideal 3D MTFs; FWHM and FWTM results quantitatively show that the proposed method provides reliable estimation performance. In particular, the estimated 3D MTF in a missing cone region was correctly matched with the corresponding ideal 3D MTF. Conclusions: In this work, we proposed a full 3D MTF estimation method for CBCT systems. Based on the results, we believe that the proposed method can be used to evaluate the spatial resolution performance of CBCT systems. [ABSTRACT FROM AUTHOR]

Objectives: To assess whether the evolution of two consecutive high-resolution computed tomography (HRCT) scores in patients with cystic fibrosis (CF) has prognostic value.Methods: A longitudinal retrospective study was performed to research adult patients with CF. Two consecutive HRCT studies were scored using Bhalla and Brody II scoring scales by two senior radiologists. Annual scoring changes for each scale were calculated and correlated with annual FEV1% decline, with pulmonary exacerbations and number of antibiotic treatments.Results: We selected sixty-four adult patients. The median interval between the two HRCTs was 3.88 ± 1.59 years. The mean spirometric values showed dynamic lung volumes lower than the general population; globally, there was a worsening of respiratory function over time. The change in the annual HRCT scores was positive on both scales, indicating a worse structural situation over time. The Brody II scale annual change showed a significant statistical correlation with a decline in the annual FEV1%, exacerbations and number of oral antibiotic treatments. In contrast, for the Bhalla scale, the relationship was moderately inverse with exacerbations and with the number of oral treatments. No statistically significant relationships were found for the change in the annual FEV1% and exacerbations or number of antibiotic treatments. The interobservational and intraobservational agreements were very strong in both scales.Conclusions: The annual evolution of the Brody II HRCT scoring system demonstrated a predictive value and correlated with FEV1% decline, pulmonary exacerbations and oral antibiotic treatments.Key Points: • HRCT evolution has prognostic value in cystic fibrosis. • Temporal evolution for the Brody II score is useful for clinical follow-up. • Brody II score changes correlate with FEV1% decline, pulmonary exacerbations and number of antibiotic treatments. [ABSTRACT FROM AUTHOR]

This article discusses the features of the collimation system of a tomograph for monitoring steel products by Compton backscattering. The analysis of the aperture functions of the scattering volume for the ring-type detector with different sizes of the pinholes of the primary and secondary collimators is carried out. The efficiency of using a ring type detector is shown. Recommendations to select pinhole sizes of the primary and secondary collimators are given. An indirect estimation of the possible scanning depth of steel products is given. [ABSTRACT FROM AUTHOR]

Introduction: Complex renal cystic lesions have long posed a clinical dilemma to clinicians as they represent a heterogeneous group of both benign and malignant conditions sharing similar clinical and radiological features. The Bosniak classification system based on computed tomography (CT) imaging remains the gold standard to predict the risk of malignancy in cystic renal masses. We retrospectively reviewed our series of patients who underwent surgery for renal cysts, their histopathological diagnosis, the outcome of surgery, and follow-up. Materials and Methods: We retrospectively reviewed the inpatient charts of the hospital for patients with renal cysts undergoing surgery for the same during the period January 2000-December 2017. CT images of these patients were re-reviewed. Clinical, surgical, radiological, pathological, and postoperative outcomes were analyzed. Based on the final pathology findings, the patients were stratified into a renal cell carcinoma (RCC) or a benign tumor subgroup. Results: During the 18-year study period, 31 patients with Bosniak I simple renal cysts, 23 with Bosniak 2 cysts, 1 patient with Bosniak IIF cyst, 8 with III cyst, and 11 with IV cyst underwent surgery. None of the patients with Bosniak I, II, and IIF had malignancy on histopathological examination (HPR) of the resected cyst wall. Five of the eight patients with Bosniak III and all 11 patients with Bosniak IV cysts had malignant lesions. Histopathological variety of RCC was clear cell type with Fuhrman Grade 1–2 in all the 16 patients. None of the patients have had either local or systematic recurrence of the malignancy. Five patients died during the follow-up period due to causes other than malignancy. Conclusions: Patients with unifocal cystic RCC evaluated and managed using standard imaging carry an excellent prognosis. Bosniak classification system is very effective in predicting malignancy in categories II, IIF, and IV, but low in category III, and that 37.5% of Bosniak III cysts were benign on HPR. [ABSTRACT FROM AUTHOR]

Background: Xanthogranulomatous cholecystitis (XGC) is an uncommon variant of chronic cholecystitis. The differential diagnoses of XGC include gallbladder cancer (GBC), adenomyomatosis, and actinomycosis of the gallbladder. Purpose: To assess the usefulness of computed tomography (CT) findings in the diagnosis of XGC and differentiation from GBC. Material and Methods: We retrospectively assessed the pathological and radiological records of 13 patients with pathologically proven XGC and 33 patients with GBC. Results: Significant differences were observed for the following five CT findings: diffuse wall thickening (XGC = 85%, GBC = 15%, P < 0.01); absence of polypoid lesions (XGC = 100%, GBC = 48%, P < 0.01); intramural nodules or bands (XGC = 54%, GBC = 9%, P < 0.01); pericholecystic infiltration (XGC = 69%, GBC = 9%, P < 0.01); and pericholecystic abscess (XGC = 23%, GBC = 0%, P = 0.018). We defined the scoring system based on how many of the five CT findings were observed. Our scoring system, which included these findings, revealed that patients with three or more findings had sensitivity of 77% (95% confidence interval [CI] = 57–87) and specificity of 94% (95% CI = 86–98). Conclusion: Our scoring system can assist in the differentiation of XGC from GBC. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the sealing ability of different self-etch dental adhesives after different aging protocols. Sixty sound human third molars were used for this study. Two standardized Class II box cavities, with the gingival floor 1 mm below the cement-to-enamel junction were prepared in each tooth. Three adhesive groups (Clearfil SE Bond, Clearfil S3 Bond and Single Bond Universal) were subdivided into four subgroups (n = 10) according to the aging protocols: 24 h water storage (control); 1-year water aging; 10,000 thermocycling; and 240,000 thermo-mechanical aging. After the aging protocols, a 50% silver nitrate solution was used as a tracer. The internal adaptation analysis was performed using a micro computed tomography system. All tested aging protocols increase the silver nitrate penetration compared with the controls (p < 0.05). The samples aged in water have no significant difference with the samples aged with thermocycling (p > 0.05). The amount of silver nitrate penetration increased after thermo-mechanical aging for all samples (p < 0.05).The tested adhesives presented different marginal sealing abilities after thermo-mechanical loading and two-step self-etch adhesive showed lower silver nitrate penetration than one-step systems (p < 0.05). [ABSTRACT FROM AUTHOR]

Purpose: The increasing interest and availability of non-standard positron-emitting radionuclides has heightened the relevance of radionuclide choice in the development and optimization of new positron emission tomography (PET) imaging procedures, both in preclinical research and clinical practice. Differences in achievable resolution arising from positron range can largely influence application suitability of each radionuclide, especially in small-ring preclinical PET where system blurring factors due to annihilation photon acollinearity and detector geometry are less significant. Some resolution degradation can be mitigated with appropriate range corrections implemented during image reconstruction, the quality of which is contingent on an accurate characterization of positron range.Procedures: To address this need, we have characterized the positron range of several standard and non-standard PET radionuclides (As-72, F-18, Ga-68, Mn-52, Y-86, and Zr-89) through imaging of small-animal quality control phantoms on a benchmark preclinical PET scanner. Further, the Particle and Heavy Ion Transport code System (PHITS v3.02) code was utilized for Monte Carlo modeling of positron range-dependent blurring effects.Results: Positron range kernels for each radionuclide were derived from simulation of point sources in ICRP reference tissues. PET resolution and quantitative accuracy afforded by various radionuclides in practicable imaging scenarios were characterized using a convolution-based method based on positron annihilation distributions obtained from PHITS. Our imaging and simulation results demonstrate the degradation of small animal PET resolution, and quantitative accuracy correlates with increasing positron energy; however, for a specific "benchmark" preclinical PET scanner and reconstruction workflow, these differences were observed to be minimal given radionuclides with average positron energies below ~ 400 keV.Conclusion: Our measurements and simulations of the influence of positron range on PET resolution compare well with previous efforts documented in the literature and provide new data for several radionuclides in increasing clinical and preclinical use. The results will support current and future improvements in methods for positron range corrections in PET imaging. [ABSTRACT FROM AUTHOR]

The glial–lymphatic pathway is a fluid-clearance pathway consisting of a para-arterial route for the flow of cerebrospinal fluid along perivascular spaces and subsequently toward the brain interstitium. In this case series, we aim to investigate an empirical demonstration of glymphatic clearance of extravasated iodine following perforation incurred during endovascular therapy on serial computed tomography. Six consecutive cases of endovascular perforation during thrombectomy performed between 2005 and 2018 were retrospectively collected by searching our internal database of total 446 thrombectomies. Two cases were excluded because care was withdrawn shortly following the procedure and no follow-up imaging was available. One case was excluded because a ventricular drain was placed. Three cases were hence included in this analysis. All 3 cases demonstrated progressive absorption of contrast by the brain parenchyma with eventual contrast disappearance. We described a likely in vivo computed tomography correlate of the glymphatic system in a cohort of patients who sustained intraprocedural extravasation during thrombectomy for acute ischemic stroke. [ABSTRACT FROM AUTHOR]

Purpose: Two ultra‐high‐resolution (UHR) computed tomography (CT) scanners are clinically available. One is achieved by a CT system with a 0.25 mm × 160 row detector (Detector‐UHR), whereas the other is with a 0.6 mm × 32 row detector with in‐plane comb filtering in a dual source CT (Comb‐UHR). We compared radiation dose efficiencies of the two UHR modes to that of a routine scan mode (RS), using physical image quality measures for an assumed condition of abdominal CT angiography (CTA). Methods: A wire phantom, a 300‐mm cylindrical water bath phantom, and a microdisk phantom were used for measuring the modulation transfer function (MTF), noise power spectrum (NPS), and slice sensitivity profiles (SSP), respectively, at CTDIvol of 20 mGy. Images with minimal slice thicknesses were reconstructed by filtered back projection methods. System performance functions (SPF2) based on the prewhitening theorem were calculated by dividing MTF2 by NPS measurements. The ideal observer's detectability index (d'2) was also estimated for a task corresponding to a 1‐mm diameter vessel. Furthermore, a bar‐pattern phantom placed in a water phantom resembling an adult abdomen was scanned, and the visibility of the bars was observed. Results: System performance function (SPF2) results showed that Comb‐UHR has a 70% dose efficiency compared to RS and provides better than twofold SPF2 compared to Detector‐UHR. The d'2 values of Detector‐UHR, Comb‐UHR, and RS were 6.5, 14.7, and 16.0, respectively. Although the bar‐pattern phantom images were consistent with the SPF results, bar widths < 1.0 mm for Detector‐UHR and < 0.75 mm for Comb‐UHR and RS were not resolved. Conclusions: Though both the UHR modes exhibited system performances extending to 2.6 cycles/mm, they appeared not to be advantageous compared to RS in the conditions applicable to abdominal CTA, because of their insufficient dose efficiencies. [ABSTRACT FROM AUTHOR]

Study Design: Prospective comparative study. Purpose: To compare the incidence of iatrogenic superior facet joint violation (SFV) in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and open TLIF (OPEN-TLIF) at a single lower lumbar fusion level and to evaluate the patient and surgical factors influencing the outcome. Overview of Literature: Iatrogenic SFV is a significant risk factor for adjacent segment disease (ASD). Blind screw placement technique in MIS-TLIF contributes to the increasing incidence of iatrogenic SFV which can be influenced by several other potential factors. There are only limited studies comparing the incidence of iatrogenic SFV in MIS-TLIF and OPEN-TLIF. Methods: In total, 225 cases (450 top screws; MIS-TIFL, 120; OPEN-TILF, 105) undergoing single-level lower lumbar fusion were included in the study. Postoperative computed tomography grading system was used to evaluate iatrogenic SFV. Patient and surgical factors such as age, body mass index, top-screw level, side of the top screw, depth of the spine, and superior facet joint angle (SFA) were analyzed in iatrogenic SFV and non-violation groups to determine their influence on iatrogenic SFV. The clinical outcomes in both groups were assessed preoperatively and postoperatively. Results: The overall incidence of iatrogenic SFV and high-grade violations was higher in MIS-TLIF (41.25%) than in OPEN-TLIF (30.4%). In both groups, bivariate analysis showed a significantly greater incidence of the iatrogenic SFV in patients aged <60 years and those with obesity, top pedicle screws at L4, right-sided top screws, SFA >35°, and depth of the spine >50 mm. Conclusions: This study demonstrated that the incidence of iatrogenic SFV is greater in MIS-TLIF than in OPEN-TLIF at a single lower lumbar level. MIS-TLIF is effective for lumbar degenerative disease; however, the incidence of iatrogenic SFV was higher. Patient and surgical factors must be considered to protect the facet joints in both TLIF methods to avoid ASD. [ABSTRACT FROM AUTHOR]

Extracorporeal cardiopulmonary resuscitation (ECPR) can be associated with increased survival and neurologic benefits in selected patients with out-of-hospital cardiac arrest (OHCA). However, there remains insufficient evidence to recommend the routine use of ECPR for patients with OHCA. A novel integrated trauma workflow concept that utilizes a sliding computed tomography (CT) scanner and interventional radiology (IR) system, named a hybrid emergency room system (HERS), allowing emergency therapeutic interventions and CT examination without relocating trauma patients, has recently evolved in Japan. HERS can drastically shorten the ECPR implementation time and more quickly facilitate definitive interventions than the conventional advanced cardiovascular life support workflow. Herein, we discuss our novel workflow concept using HERS on ECPR for patients with OHCA. [ABSTRACT FROM AUTHOR]

Introduction: The performance of computed tomography is routinely checked using phantoms, which are known as important diagnostic imaging tools. Depending upon the aim of the study, different phantoms are designed, while trying to satisfy certain levels of diversities in their application. Material and Methods: The present study describes the construction of an inexpensive phantom designed for simultaneous measurements of 12 different samples. The body of the phantom, test tube holders, and test tubes were made of materials of low attenuation coefficient. Body of the phantom was filled with water. Test tubes filled with solutions of known chemical compositions were mounted on the test tube holders. The whole phantom was scanned at 80, 100, 120, 140 kVp to evaluate the performance of the CT system. Using Hounsfield Unit (HU) data from these liquid samples of known electron density, the phantom was calibrated for electron density measurements. Results: The system's accuracy and reproducibility were verified by measuring the HU values for some known materials. According to the results obtained from the experimental data with liquid samples, the accuracy of the water and noise was within ±3.2 HU and 0.6%, respectively. Moreover, the image uniformity error was less than ±2 HU, and CT system's linearity for calibration was estimated with 99.9% confidence. Conclusion: The present system gives satisfactory results with known samples and can be used with confidence for characterizing unknown materials. [ABSTRACT FROM AUTHOR]

A method for the time calibration of the Time-of-Flight Positron Emmission Tomograph (TOF-PET) systems using fixed sources is described. Compared to the commercially used calibration methods, the new method gives a chance to run the calibration during the medical scan. Reduction of the time needed for calibration can increase the number of patients examined by PET. The process of calibration of the Jagiellonian Positron Emission Tomograph (J-PET) detector is shown as an example. [ABSTRACT FROM AUTHOR]

Background: Nontraumatic headache is a frequent complaint in the emergency department (ED). Cranial computed tomography (CT) is a widely available test for the diagnostic work-up, despite the risk of exposure to ionizing radiation.Objectives: We sought to develop and evaluate a cranial CT request computerized decision support system (CDSS) for adults with their first presentation of unusual severe nontraumatic headache in the ED.Methods: Electronic database searches identified clinical decision and prediction rules and studies delineating risk factors in nontraumatic headache. A long list of risk factors extracted from these articles was reduced by a 30-member multidisciplinary expert panel (radiologists, emergency physicians, methodologists), using a 90% agreement threshold. This shortlist was used to develop the algorithm for the cranial CT request CDSS, which was implemented in March 2016. Impact evaluation compared CT scan frequency and diagnostic yield of pathologic findings before (March-August 2015) and after (March-August 2016) implementation.Results: From the 10 selected studies, 10 risk factors were shortlisted to activate a request for cranial CT. Before implementation, 377 cranial CTs were ordered (15.3% of 2469 CT scans) compared with 244 after (9.5% of 2561 CT scans; pre-post difference 5.74%; 95% confidence interval [CI] 3.92-7.56%; p < 0.001), corresponding to a 37.6% relative reduction in the test ordering rate (95% CI 25.7-49.5%; p < 0.001). Despite the reduction in cranial CT scans, we did not observe an increase in pathological findings after introducing the decision support system (70 cases before [18.5%] vs. 35 cases after [14.3%]; pre-post difference -4.0% [95% CI -10.0 to 1.6%]; p = 0.170).Conclusion: In nontraumatic headache among adults seen in the ED, CDSS decreased the cranial CT request rate but the diagnostic yield did not improve. [ABSTRACT FROM AUTHOR]

Background: The rapid development and complexity of new x‐ray computed tomography (CT) technologies and the need for evidence‐based optimization of image quality with respect to radiation and contrast media dose call for an updated approach towards CT performance evaluation. Aims: This report offers updated testing guidelines for testing CT systems with an enhanced focus on the operational performance including iterative reconstructions and automatic exposure control (AEC) techniques. Materials and Methods: The report was developed based on a comprehensive review of best methods and practices in the scientific literature. The detailed methods include the assessment of 1) CT noise (magnitude, texture, nonuniformity, inhomogeneity), 2) resolution (task transfer function under varying conditions and its scalar reflections), 3) task‐based performance (detectability, estimability), and 4) AEC performance (spatial, noise, and mA concordance of attenuation and exposure modulation). The methods include varying reconstruction and tube current modulation conditions, standardized testing protocols, and standardized quantities and metrology to facilitate tracking, benchmarking, and quantitative comparisons. Results: The methods, implemented in cited publications, are robust to provide a representative reflection of CT system performance as used operationally in a clinical facility. The methods include recommendations for phantoms and phantom image analysis. Discussion: In line with the current professional trajectory of the field toward quantitation and operational engagement, the stated methods offer quantitation that is more predictive of clinical performance than specification‐based approaches. They can pave the way to approach performance testing of new CT systems not only in terms of acceptance testing (i.e., verifying a device meets predefined specifications), but also system commissioning (i.e., determining how the system can be used most effectively in clinical practice). Conclusion: We offer a set of common testing procedures that can be utilized towards the optimal clinical utilization of CT imaging devices, benchmarking across varying systems and times, and a basis to develop future performance‐based criteria for CT imaging. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the association between individual risk factors and coronary artery calcification (CAC), as a marker of subclinical cardiovascular disease, in a population-based nested cross-sectional study of midlife women. Anthropometric and metabolic data from 295 women from the South of Brazil were analyzed. Habitual physical activity was assessed by pedometer. CAC was assessed by a multi-detector computed tomography system. Average Agatston score was used to stratify participants as CAC > 0 and CAC = 0. Women with CAC > 0 (34.7%) were older (58.7 ± 5.4 vs. 56.3 ± 5.2 years, p <.001) and had higher prevalence of central adiposity (71 vs. 59%, p =.04) and hypertension (71 vs. 52%, p =.002) than women in the CAC = 0 group. Hormone therapy (HT) was more prevalent in the group with CAC = 0 (19.7 vs. 9.8%, p =.029). The prevalence ratios for CAC > 0 were 0.545 (95%CI:0.309–0.962, p =.036) for HT and 1.752 (95%CI:1.207–2.541, p =.003) for hypertension, after adjustment for age, educational level, smoking, alcohol intake, and physical activity. The present data in a population-based sample of midlife women indicate that hypertension and age were positively associated with higher risk for CAC > 0 and HT was related with CAC = 0. [ABSTRACT FROM AUTHOR]

To better understand the basic properties and phenomena of compression failure in rock mass structures, a series of uniaxial compression tests on sandstone specimens was carried out using loading equipment, an acoustic emission system, a computed tomography scanning system and a high-speed video camera. The results showed that the fracture process of sandstone samples was divided into three stages: original micro-crack closure, micro-crack nucleation and macro-crack propagation. Avalanche energies of the intact and single-fissured specimens followed a power-law distribution, which revealed avalanche criticality. The optimal exponents (r ) of single-fissured specimens were about 1.64 and were slightly lower than that of the intact specimen. The fitted power-law exponents ( r ′ ) of sandstone specimens change in the different stages of experiments and gradually tend to a stable value, which acted as a "warning signal" for the impending major collapse. Based on histogram analysis and the maximum likelihood method, the presence of a flaw may affect the statistical properties of avalanche energies. The flaw inclination angle had little influence on the optimal exponent, but it had certain influence on the fracture modes of the specimens. This paper may provide a new theoretical basis for predicting the collapse failure of engineering rock mass structures. [ABSTRACT FROM AUTHOR]

Glioblastoma (GBM) is the most common aggressive malignant primary brain tumor, rarely concurrent in patients who require deep brain stimulation (DBS) implants. Despite the high incidence of these circumstances alone, the coexistence of both in a patient has been seldom reported. In this paper, we report a case of a patient suffering from a movement disorder treated with DBS who developed a GBM. A patient with bilateral DBS of the globus pallidus internus for refractory secondary dystonia developed a GBM close to the electrode leads, 2.5 years after implantation. The clinical findings, medical management and pitfalls, and possible relationship between the DBS device and the tumor development are discussed. We withdrew the system to perform brain magnetic resonance imaging safely. This revealed an extended lesion that was biopsied. The removal led to a clinical worsening that resulted in fatality, without the possibility of receiving adjuvant treatment. The available literature shows similar management, which depends mainly on the stimulation system used. We advise the use of magnetic resonance imaging–safe devices; otherwise, we recommend keeping the system and proceeding with computed tomography imaging for diagnostic and management if necessary. The true relationship between chronic DBS stimulation and GBM is to be clarified. [ABSTRACT FROM AUTHOR]

BACKGROUND: Intraoperative computed tomography (iCT) system has been developed focusing on combining the advanced imaging techniques for the best imaging modality. However, the use of iCT system in the operating rooms is limited due to the lack of flexible mobility. OBJECTIVE: This study aims to develop a mobile iCT imaging system and assess its imaging performance in a phantom study. METHODS: The mobile iCT system with mecanum omni-directional wheels has three major components namely, a rotating gantry, a slip-ring and a stationary gantry. Performance of mecanum iCT system was evaluated using the indices of signal-to-noise (SNR), contrast-to noise (CNR), and spatial resolution (MTF). Anatomical landmarks on phantom images were assessed using a 5-point scale (5 = definitely seen; 4 = probably seen; 3 = equivocal; 2 = probably not seen; and 1 = definitely not seen). RESULTS: The mecanum iCT system can be conveniently used for a whole-body scan under intraoperative conditions even in narrow operating rooms due to a smaller turning radius. The image quality of the mecanum iCT system was found to be acceptable for clinical applications (with SNR = 162.72, CNR = 134.29 and MTF = 694 μm). The diagnostic scores on the phantom images were 'definitely seen' value. CONCLUSIONS: The proposed mecanum iCT system achieved the improved flexible mobility and has potential to better serve as a useful imaging tool in the clinical intraoperative setting. [ABSTRACT FROM AUTHOR]

In this study, a new CT measurement system was developed for preoperation evaluation of total knee replacement (TKR). To validate the developed imaging processing systems, TKR patients with and without a bowed lower limb were recruited. All patients underwent plain radiographs and CT scan before a TKR procedure. The precision and effectiveness of two measurements validated by an orthopedic surgeon and evaluated using the developed 3D computed tomography image system were compared. In vivo statistics data, particularly for Taiwanese patients, showed no difference between bowed lower limb and normal lower limb groups. The results of this study did not reveal a significant difference between the 3D-reconstructed CT images and 2D plain radiographs. However, the proposed 3D-reconstructed CT image measurement system demonstrated consistent measurements for TKR patients and for the bowed lower limb group in preoperative evaluation. The implemented system could be used in conjunction with the current 2D radiograph approach. The proposed system assist surgeons and patients when discussing operations and clinical approaches. Clinical results validated the system. [ABSTRACT FROM AUTHOR]

Using X-ray computed tomography (CT) as an industrial measurement tool requires the development of standards and reference objects for calibration. The purpose of this paper is to describe a manufacturing process for a reference object made from silicon and containing cavities with sub-millimeter features. Lithographic processes are used to etch silicon wafers to produce features arranged within 4 × 4 mm2 areas. The patterned wafer is diced and multiple pieces are bonded to form a 2 mm thick layered solid. For ease of handling, a protective shell is fabricated around the silicon stack and is made from glass and UV cure epoxy. Measurements obtained by coherence scanning interferometry (CSI) and CT are used to illustrate a comparative data analysis. Because different systems and process parameters would result in different measures of performance, no attempt has been made to optimize measurement procedures in this study. A feature with major dimensions 300 μm by 400 μm and containing a cubic shaped edge was extracted from the CT data. From the same wafer, a different pattern containing a similar feature was measured by CSI. Linear dimensions between edges from nominal were within 1 μm for the CSI measurements and up to 3.1 μm for the CT. The curve shape edge was fitted to the coefficients of a nominal shape and to best fit coefficients of a cubic polynomial. Both fits resulted in comparable residuals with standard deviations from nominal fit of 0.141 μm for CSI and 0.387 μm for CT, and respectively 0.117 μm and 0.320 μm for the polynomial fits. • This study demonstrates a design of a direct bonded silicon reference object for X-ray CT dimensional metrology studies. • Features were patterned and etched onto silicon wafer surfaces and wafers bonded into a stack to create engineered cavities. • A comparison of CT and CSI data provides an example of spatial dimension and curve fitting for a feature with a cubic curve. [ABSTRACT FROM AUTHOR]

Highlights • Development of a state-of-the-art computed tomography system capable of tracking ballistic-velocity unbounded material through a three-dimensional coordinated system. • Utilizes flash X-radiography technology to penetrate outer material layers. • Utilizes customized iterative reconstruction routines within Lawrence Livermore National Laboratory's "Livermore Tomography Tools" software suite to computationally reconstruct multiple X-ray projections into a 3-D volume. • Demonstrates the first example using a bullet penetrating an aluminum plate. Abstract The U.S. Army Research Laboratory (ARL) and Lawrence Livermore National Laboratory have developed a high speed computed tomography system that is capable of tracking unbounded material flux through a reconstruction volume at ballistic rates. It achieves this feat by creating three individual time-registered volume reconstructions throughout the duration of a single dynamic event. Each individual volume reconstruction is computed from five attenuation projections, which are collected using five flash X-ray sources and five digital imaging plate detectors. This work summarizes the numerous complexities in combining the 15 sources and 15 detectors into a single diagnostic, the complexities of analyzing multiple reconstruction volumes from a limited number of views, and complications associated with designing an experiment to fit within the bounding conditions of the diagnostic. It continues to demonstrate an example of how free-flowing material propagates through a reconstruction volume during a bullet/target interaction. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the sensitivity and specificity of 3 different systems of cone-beam computed tomography (CBCT) in the detection of natural external root resorption (ERR) cavities using microtomography as the gold standard. A sample of 126 ex vivo teeth were submitted to a microtomography examination to verify the presence/absence of ERR cavities. Then, they were divided into the control group: 85 teeth that did not present with an ERR cavity; and experimental group: 41 teeth that presented with 1 or more ERR cavities. The size of the natural ERR cavities varied from 2.46 mm3 to 3.11 mm3, which corresponded to cavities of 1.67 mm and 1.81 mm in diameter, respectively. The teeth were placed on a dry human mandible for scanning in each of the 3 protocols with different voxel sizes: 0.25 mm, 0.20 mm, and 0.166 mm. The accuracy of the 3 protocols evaluated in this study are listed in decreasing order: 60.3% for a voxel size of 0.20 mm, 56.7% for a voxel size of 0.166 mm, and 46.7% for a voxel size of 0.25 mm; these are smaller values than previous studies have obtained using artificial ERR cavities. Statistically significant results were not found among the 3 CBCT protocols that were used (P >.05), and the receiver operating characteristic curve shows the small differences found between the protocols. The results indicate that CBCT presents, for natural ERR, lower sensitivity and specificity values than those detected in previous studies of artificial cavities. The results demonstrate that natural ERR is neither easily observed nor accurately located by CBCT, as previous studies using artificial ERR indicated. • Compare sensitivity and specificity of 3 different CBCTs in the detection of natural ERR cavities. • Architecture of ERRs is different from each other in shape and size. • According to the findings of this study, voxel size 0.25 mm is not valuable or useful for the ERR evaluation. [ABSTRACT FROM AUTHOR]

Abstract The Thin-TOF PET (TT-PET) project aims at the construction of a small-animal PET scanner based on silicon monolithic pixel sensors with 30 ps time resolution for 511 keV photons, equivalent to 100 ps time resolution for minimum ionizing particles. The high time resolution of the pixel sensor allows for precise time of flight measurement of the two photons and a significant improvement in the signal-to-noise ratio of images. The TT-PET scanner also has sensitivity for photon depth of interaction, thus improving the spatial resolution across the whole view of the scanner. The performance of the scanner estimated by a GEANT4 Monte Carlo simulation is presented. In order to achieve the high time resolution, the SiGe heterojunction bipolar transistor technology (SG13S from IHP) was chosen for fast integration, low equivalent noise charge and low power consumption. TCAD simulations were used to design the appropriate guard rings for the pixel sensor. Laboratory measurements of the first test chip show the correct functionality of the guard ring up to a bias potential of 200 V applied to the pixels and a good signal-to-noise ratio for the detection of electrons from a 90Sr source. A test beam measurement with an un-thinned chip shows more than 99 % efficiency and approximately 200 ps time resolution for minimum ionizing particles despite the absence of wafer thinning and post-processing. Highlights • The Thin-TOF PET (TT-PET) project aims at the construction of a TOF PET scanner. • The robustness of the first prototype against breakdown up to a potential 160 V. • First prototype shows a time resolution of 200 ps for MIPs under a test beam. [ABSTRACT FROM AUTHOR]

Purpose: Prostate motion during the radiotherapy course is an important issue. This study investigated the inter-fraction prostate motion in controlled rectal filling condition. Methods: 10 prostate cancer patients underwent image-guided radiotherapy (IGRT) using a cone-beam computed tomography (CBCT) system, after the insertion of fiducial markers (FMs). The planning CT was the reference CT (CTref) used to estimate the reference intermarker distances, and CBCTs were used for off-line comparison with CTref. We evaluated the influence of rectal and bladder volume on prostate shifts. We calculated the required planning target volume (PTV) margins in this patient population. Results: 120 CBCTs were analyzed. Mean prostate displacements (± SD) along the 3 axes (x, y, z) averaged over the 10 patients, were: 0.90 ± 0.84 mm in x, 0.00 ± 2.07 mm in y, -0.80 ± 1.28 mm in z. There is a statistically significant anti-correlation between prostate displacements and: bladder volume variations (P < 0.001) in the y-axis, and rectal volume variations (P < 0.05) in the z-axis. PTV margins obtained for the directions x, y and z are respectively 2.5, 5.6 and 3.9 mm. Conclusion: IGRT in reproducible empty rectum condition allow a high reduction of daily treatment uncertainties. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with limited treatment options. Despite decades of therapeutic development, only two modestly efficacious disease-modifying drugs—riluzole and edaravone—are available to ALS patients. Biomarkers that can facilitate ALS diagnosis, aid in prognosis, and measure drug pharmacodynamics are needed to accelerate therapeutic development for patients with ALS. Positron emission tomography (PET) imaging has promise as a biomarker for ALS because it permits visualization of central nervous system (CNS) pathology in individuals living with ALS. The availability of PET radioligands that target a variety of potential pathophysiological mechanisms—including cerebral metabolism, neuroinflammation, neuronal dysfunction, and oxidative stress—has enabled dynamic interrogation of molecular changes in ALS, in both natural history studies and human clinical trials. PET imaging has potential as a diagnostic biomarker that can establish upper motor neuron (UMN) pathology in ALS patients without overt UMN symptoms, as a prognostic biomarker that might help stratify patients for clinical trials, and as a pharmacodynamic biomarker that measures the biological effect of investigational drugs in the brain and spinal cord. In this Review, we discuss progress made with 30 years of PET imaging studies in ALS and consider future research needed to establish PET imaging biomarkers for ALS therapeutic development. [ABSTRACT FROM AUTHOR]

Featured Application: This article describes the evaluation of the automatic classification system for computed tomography (CT) images using a deep learning technique. Additional learning for automatic training will help to create various classification models in the medical fields. The results in this study will be useful for creating new classification models. A large number of images that are usually registered images in a training dataset are required for creating classification models because training of images using a convolutional neural network is done using supervised learning. It takes a significant amount of time and effort to create a registered dataset because recently computed tomography (CT) and magnetic resonance imaging devices produce hundreds of images per examination. This study aims to evaluate the overall accuracy of the additional learning and automatic classification systems for CT images. The study involved 700 patients, who were subjected to contrast or non-contrast CT examination of brain, neck, chest, abdomen, or pelvis. The images were divided into 500 images per class. The 10-class dataset was prepared with 10 datasets including with 5000–50,000 images. The overall accuracy was calculated using a confusion matrix for evaluating the created models. The highest overall reference accuracy was 0.9033 when the model was trained with a dataset containing 50,000 images. The additional learning for manual training was effective when datasets with a large number of images were used. The additional learning for automatic training requires models with an inherent higher accuracy for the classification. [ABSTRACT FROM AUTHOR]

A low-cost Photoacoustic Computed Tomography (PACT) system consisting of 16 single-element transducers has been developed. Our design proposes a fast rotating mechanism of 360° rotation around the imaging target, generating comparable images to those produced by large-number-element (e.g., 512, 1024, etc.) ring-array PACT systems. The 2D images with a temporal resolution of 1.5 s and a spatial resolution of 240 µm were achieved. The performance of the proposed system was evaluated by imaging complex phantom. The purpose of the proposed development is to provide researchers a low-cost alternative 2D photoacoustic computed tomography system with comparable resolution to the current high performance expensive ring-array PACT systems. [ABSTRACT FROM AUTHOR]

Abstract: The design of a new automatic X-ray microtomograph is described. The parameters of optical schemes and X-ray detectors in use are presented. Methods for automating experiments, processing tomographic data, and getting access to them are reported. [ABSTRACT FROM AUTHOR]

Objective: To analyze the clinical effectiveness and safety of early interventional embolization in the treatment of ruptured cerebral aneurysm. Methods: Eighty-eight patients with cerebral aneurysm rupture who were admitted to the hospital between February 2015 and October 2016 were selected as the research subjects and were randomly divided into a control group (N=44) and an observation group (N=44) using random number table. Patients in the control group were given interventional embolization three days after admission, while patients in the observation group were given interventional embolization within three days after admission. The complete, sub complete and incomplete embolization rates were compared between the two groups. The prognosis of the patients was evaluated using modified Rankin scale and modified Barthel index. The incidences of complications were recorded. Results: The complete, sub-complete and incomplete embolization rates of the observation group and control group were significantly different (P<0.05). The modified Rankin score of the observation group was remarkably lower than that of the control group, and the modified Barthel index of the observation group was remarkably higher than that of the control group; the differences had statistical significance (P<0.05). The incidence of complications of the observation group was lower than that of the control group, and the difference had statistical significance (P<0.05). Conclusion: Early interventional embolization has satisfactory effect in the treatment of cerebral aneurysm rupture and effectively improve prognosis; hence it is worth promotion in clinical practice. [ABSTRACT FROM AUTHOR]

Abstract Unilateral condylar hyperplasia is a rare disease that causes facial asymmetry as a result of excessive vertical or horizontal growth, or both, of the mandibular condyle. Investigation should address the patient's concerns, and establish whether the disease is active with the use of single positron emission tomography (PET). Proportional reduction of the condyle arrests active disease and restores mandibular height, and any residual asymmetry can be corrected according to conventional orthognathic principles. We recommend the use of 3-dimensional virtual planning for such complex movements. The rarity of the disease means that, to our knowledge, high-quality evidence is lacking and further research is needed. [ABSTRACT FROM AUTHOR]

The authors propose a dual-energy approach to reduce cone-beam artefacts in a circular orbit cone-beam computed tomography (CT) system. When there exist multiple dense structures within a large cone angle, two-pass algorithm is ineffective for reducing cone-beam artefacts because high-density materials are incorrectly segmented with simple thresholding. The proposed algorithm utilises projection data obtained with dual-energy X-ray spectra to estimate projections of the high-density materials from multi-density anatomical structures. Using bone and water as two of basis functions, the projection data of bone materials can be precisely estimated via dual-energy scans. Then, bone-only images are reconstructed by a constrained total-variation minimisation-based iterative algorithm. The reconstructed bone images are used to generate cone-beam artefacts and the final corrected images are acquired by subtracting the generated cone-beam artefacts from the original Feldkamp, Davis, and Kress images. The proposed method was validated using an extended cardiac-torso phantom with complex vertebral anatomy and compared with the two-pass algorithm. The results show that the proposed method restores distorted bony structures and intensity values, especially in regions with large cone angles. A qualitative evaluation of the mean-squared errors and structural similarities demonstrates the effectiveness of the proposed method compared to the two-pass algorithm. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to design and simulate a new computed tomography (CT) system with a high temporal resolution for dynamic objects. We propose a multisource cubical CT (MCCT) system with X-ray tubes and detectors installed on a cube. Carbon nanotube- (CNT-) based X-ray focal spots are distributed on the twelve edges of the cube. The distribution of X-ray focal spots and detectors completely avoids mechanical movements to scan an object under inspection. CNTs are excellent electron field emitters because the use of a “cold” cathode makes it possible to fabricate a cathode with multiple electron emission points, and the CNT-based X-ray focal spots possess little response time and programmable emission. The proposed rotation-free MCCT system can acquire a high scanning speed when using a high frame rate detector. A three-dimensional (3D) reconstruction algorithm with tensor framelet-based L0-norm (TF-L0) minimization is developed for the simulation study of the MCCT. Simulation experiment results demonstrate the feasibility of the MCCT system. [ABSTRACT FROM AUTHOR]

Gamma scanning is a nuclear inspection technique widely used to troubleshoot industrial equipments in refineries and petrochemicals plants such as distillation columns and reactors. In this technique, a sealed radiation source and detector move along the equipment, and the intensity readouts generate the density profile of the equipment. Although many improvements have been introduced in recent years, the result of gamma scan still consists of a simple 1-D density plot. In this work, we present the tomographic gamma scanning that, using image reconstruction techniques, shows the result as a 2-D image of density distribution. Clearly, an image reveals more features of the equipment than a 1-D graph and many problems that could not be troubleshooted using the conventional technique can now be solved with this imaging technique. We use ART (Algebraic Reconstruction Technique) intercalated with total variation minimization filter. The use of total variation minimization leads to compressive sensing tomography, allowing to obtain good quality reconstruction from few irradiation data. We simulated the reconstruction of different density distributions. We applied the new technique to data obtained by irradiating with gamma rays phantoms that emulate industrial equipments. Finally, we present the result obtained by applying the innovative technique to real operating distillation column. It seems that the new technique has identified a problem in this equipment that is very difficult to detect using conventional gamma scan. [ABSTRACT FROM AUTHOR]

ABSTRACT: In a multi‐center patient study, using different CT scanners, CT‐based finite element (FE) models are utilized to calculate failure loads of femora with metastases. Previous studies showed that using different CT scanners can result in different outcomes. This study aims to quantify the effects of (i) different CT scanners; (ii) different CT protocols with variations in slice thickness, field of view (FOV), and reconstruction kernel; and (iii) air between calibration phantom and patient, on Hounsfield Units (HU), bone mineral density (BMD), and FE failure load. Six cadaveric femora were scanned on four CT scanners. Scans were made with multiple CT protocols and with or without an air gap between the body model and calibration phantom. HU and calibrated BMD were determined in cortical and trabecular regions of interest. Non‐linear isotropic FE models were constructed to calculate failure load. Mean differences between CT scanners varied up to 7% in cortical HU, 6% in trabecular HU, 6% in cortical BMD, 12% in trabecular BMD, and 17% in failure load. Changes in slice thickness and FOV had little effect (≤4%), while reconstruction kernels had a larger effect on HU (16%), BMD (17%), and failure load (9%). Air between the body model and calibration phantom slightly decreased the HU, BMD, and failure loads (≤8%). In conclusion, this study showed that quantitative analysis of CT images acquired with different CT scanners, and particularly reconstruction kernels, can induce relatively large differences in HU, BMD, and failure loads. Additionally, if possible, air artifacts should be avoided. © 2018 Orthopaedic Research Society. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 36:2288–2295, 2018. [ABSTRACT FROM AUTHOR]

While computed tomography (CT) is now commonly used and considered to be clinically valuable, significant DNA double-strand breaks (γ-H2AX foci) in white blood cells from adult and pediatric CT patients have been frequently reported. In this study to determine whether γ-H2AX foci and X-ray-induced naked DNA damage are suppressed by administration of the PrC-210 radioprotector, human blood samples were irradiated in a CT scanner at 50–150 mGy with or without PrC-210, and γ-H2AX foci were scored. X-ray-induced naked DNA damage was also studied, and the DNA protective efficacy of PrC-210 was compared against 12 other common “antioxidants.” PrC-210 reduced CT radiation-induced γ-H2AX foci in white blood cells to near background (P < 0.0001) at radiation doses of 50–150 mGy. PrC-210 was most effective among the 13 “antioxidants” in reducing naked DNA X-ray damage, and its addition at 30 s before an •OH pulse reduced to background the •OH insult that otherwise induced >95% DNA damage. A systemic PrC-210 dose known to confer 100% survival in irradiated mice had no discernible effect on micro-CT image signal-to-noise ratio and CT image integrity. PrC-210 suppressed DNA damage to background or near background in each of these assay systems, thus supporting its development as a radioprotector for humans in multiple radiation exposure settings. [ABSTRACT FROM AUTHOR]

Background & Aims There are limited data on the association between non-alcoholic fatty liver disease (NAFLD) and subclinical coronary atherosclerosis. This study investigated the influence of NAFLD on subclinical coronary atherosclerosis as detected by coronary computed tomography angiography (CCTA) in an asymptomatic population. Methods A total of 5,121 consecutive asymptomatic individuals with no prior history of coronary artery disease or significant alcohol intake voluntarily underwent abdominal ultrasonography and CCTA as part of a general health examination. Fatty liver was assessed by ultrasonography examination. The fatty liver index and NAFLD fibrosis score were also calculated. Coronary atherosclerotic plaques on CCTA were evaluated. The association between NAFLD and subclinical coronary atherosclerosis was determined by logistic regression analysis. Results Of the study participants, 1,979 (38.6%) had ultrasonography-diagnosed NAFLD. After adjustment for cardiovascular risk factors, there were no statistically significant differences in the adjusted odds ratios of NAFLD for calcified plaque (1.03; 95% CI 0.89–1.20; p =  0.673) and mixed plaque (1.15; 95% CI 0.93–1.42; p =  0.214). However, adjusted odds ratios for any atherosclerotic plaque (1.18; 95% CI 1.03–1.35; p =  0.016) and non-calcified plaque (1.27; 95% CI 1.08–1.48; p =  0.003) were significantly higher in NAFLD. In addition, there was a significant association of fatty liver index ≥30 with non-calcified plaque (1.37; 95% CI 1.14–1.65; p =  0.001) and NAFLD fibrosis score ≥−1.455 with non-calcified plaque (1.20; 95% CI 1.08–1.42; p =  0.030). Conclusions In this large cross-sectional study of asymptomatic individuals undergoing CCTA, NAFLD was consistently associated with non-calcified plaque, suggesting an increased cardiovascular risk. Lay summary In asymptomatic individuals, non-alcoholic fatty liver disease (NAFLD) was an independent risk factor for non-calcified plaque, which has been known as a vulnerable plaque associated with sudden and unexpected cardiac events. Therefore, appropriate medical therapy for NAFLD was required to reduce future cardiac events. [ABSTRACT FROM AUTHOR]

Malan loess is a grayish yellow or brownish yellow, clastic, highly porous and brittle late Quaternary sediment formed by the accumulation of windblown dust. The present-day pore structure of Malan loess is crucial for understanding the loessification process in history, loess strengths and mechanical behavior. This study employed a modern computed tomography (CT) device to scan Malan loess samples, which were obtained from the east part of the Loess Plateau of China. A sophisticated and efficient workflow for processing the CT images and constructing 3D pore models was established by selecting and programming relevant mathematical algorithms in MATLAB, such as the maximum entropy method, medial axis method, and node recognition algorithm. Individual pipes within the Malan loess were identified and constructed by partitioning and recombining links in the 3D pore model. The macropore structure of Malan loess was then depicted using quantitative parameters. The parameters derived from 2D images of CT scanning included equivalent radius, length and aspect ratio of pores, porosity, and pore distribution entropy, whereas those derived from the constructed 3D structure models included porosity, coordination number, node density, pipe radius, length, length density, dip angle, and dip direction. The analysis of these parameters revealed that Malan loess is a strongly anisotropic geomaterial with a dense and complex network of pores and pipes. The pores discovered on horizontal images, perpendicular to the vertical direction, were round and relatively uniform in shape and size and evenly distributed, whereas the pores discovered on vertical images varied in shape and size and were distributed in clusters. The pores showed good connectivity in vertical direction and formed vertically aligned pipes but displayed weak connectivity in horizontal directions. The pipes in vertical direction were thick, long, and straight compared with those in horizontal directions. These results were in good agreement with both numerical simulation and laboratory permeability tests, which indicate that Malan loess is more permeable in the vertical direction than in the horizontal directions. [ABSTRACT FROM AUTHOR]