Comprehensive evaluations of a prototype full field-of-view photon counting CT system through phantom studies.

Objective. Photon counting CT (PCCT) has been a research focus in the last two decades. Recent studies and advancements have demonstrated that systems using semiconductor-based photon counting detectors (PCDs) have the potential to provide better contrast, noise and spatial resolution performance compared to conventional scintillator-based systems. With multi-energy threshold detection, PCD can simultaneously provide the photon energy measurement and enable material decomposition for spectral imaging. In this work, we report a performance evaluation of our first CdZnTe-based prototype full-size PCCT system through various phantom imaging studies.Approach.This prototype system supports a 500 mm scan field-of-view and 10 mmz-coverage at isocenter. Phantom scans were acquired using 120 kVp from 50 to 400 mAs to assess the imaging performance on: CT number accuracy, uniformity, noise, spatial resolution, material differentiation and quantification.Main results.Both qualitative and quantitative evaluations show that PCCT, under the tested conditions, has superior imaging performance with lower noise and improved spatial resolution compared to conventional energy integrating detector (EID)-CT. Using projection domain material decomposition approach with multiple energy bin measurements, PCCT virtual monoenergetic images have lower noise, and good accuracy in quantifying iodine and calcium concentrations. These results lead to increased contrast-to-noise ratio (CNR) for both high and low contrast study objects compared to EID-CT at matched dose and spatial resolution. PCCT can also generate super-high resolution images using much smaller detector pixel size than EID-CT and greatly improve image spatial resolution.Significance.Improved spatial resolution and quantification accuracy with reduced image noise of the PCCT images can potentially lead to better diagnosis at reduced radiation dose compared to conventional EID-CT. Increased CNR achieved by PCCT suggests potential reduction in iodine contrast media load, resulting in better patient safety and reduced cost.

Successful resection of pancreatic carcinoma recurrence in the remnant pancreas after a pancreaticoduodenectomy.

We present a rare case in which a pancreatectomy was performed for a recurrent tumor in the remnant pancreas after a pancreaticoduodenectomy, and we review the associated literature. A 67-year old man underwent pancreaticoduodenectomy for pancreatic cancer on April 9, 2003. The tumor was composed of well differentiated adenocarcinoma and diagnosed as R0, pT2, pN1, pM0, pStage III according to UICC TNM classification. Five years and eight months later, his serum level of carcinoembryonic antigen was found to be elevated, and a computed tomography showed a low-density mass near the site of the pancreaticojejunostomy and dilatation of the jejunal stump. We conducted a total resection of the remnant pancreas including pancreaticojejunostomy, splenectomy and peripancreatic lymph node dissection without any residual macroscopic tumor. Histologically, it was diagnosed as a well differentiated adenocarcinoma, similar to the initial tumor. It is difficult to assess whether this tumor developing in the remnant pancreas was a local recurrence or a second primary cancer. However, we believe this tumor was a second primary tumor because of the long interval period and the absence of a neoplastic invasion in the resection margins of the initial specimens.

Soft-sensor development for monitoring the lysine fermentation process.

Monitoring cell growth and target production in working fermentors is important for stabilizing high level production. In this study, we developed a novel soft sensor for estimating the concentration of a target product (lysine), substrate (sucrose), and bacterial cell in commercially working fermentors using machine learning combined with available on-line process data. The lysine concentration was accurately estimated in both linear and nonlinear models; however, the nonlinear models were also suitable for estimating the concentrations of sucrose and bacterial cells. Data enhancement by time interpolation improved the model prediction accuracy and eliminated unnecessary fluctuations. Furthermore, the soft sensor developed based on the dataset of the same process parameters in multiple fermentor tanks successfully estimated the fermentation behavior of each tank. Machine learning-based soft sensors may represent a novel monitoring system for digital transformation in the field of biotechnological processes.

Data science-based modeling of the lysine fermentation process.

Mathematical modeling of the fermentation process is useful for understanding the influence of operating parameters on target production and control performance, depending on the situation, to stabilize the target production at a high-level. However, the previous approaches using physical modeling methods and traditional knowledge-based methods are difficult to apply on working fermentors at a commercial plant scale because they have unknown and unmeasured parameters involved in target production. This study focused on developing an ensemble learning model that can predict the amino acid fermentation process behavior based on observation values, which can be obtained from fermentation tanks and future control input. The results revealed the influence of each control input on lysine production during the culturing period. Furthermore, high-order stability, which achieved the target trajectory for lysine production, was realized using dynamic fermentation controls. Additionally, this study demonstrates that the fermentation behavior on a commercial plant scale is reproduced using the ensemble device. The ensemble learning model will provide novel control system with data-science based model of Industry 4.0 in the field of biotechnological processes.

Developing nonstationary noise estimation for application in edge and corner detection.

Accurate estimation of noise and signal power is of fundamental interest in a wide variety of vision applications as it is critical to thresholding and decision processes. This paper proposes two methods for the estimation of nonstationary noise based upon models of image structure which locally separate signal from noise. The resulting algorithms are noniterative and thereby fast. The accuracy of the proposed and existing methods is compared, first separately and then in application to two common image processing tasks: edge and corner detection. It is demonstrated that the proposed model can be used to improve the stability of both, in the presence of contrast change and nonstationary noise.

Degradation of cyanuric acid in soil by Pseudomonas sp. NRRL B-12227 using bioremediation with self-immobilization system.

The rates of degradation of cyanuric acid, a key intermediate in a metabolic pathway of s-triazine herbicides, were measured for Pseudomonas sp. NRRL B-12227. The rate of degradation was affected by the rate of cyanuric acid transport through cell membranes and the activity of cyanuric acid amidohydrolase inside the cells. At low concentrations of cyanuric acid, the acclimation of cells to cyanuric acid and/or added nutrients effectively enhanced the degradation rate. The strain was also applied to bioremediation using a Bioremediation with Self-Immobilization System (BSIS), in which Pseudomonas sp. NRRL B-12227 cells were co-immobilized with Bacillus subtilis, the latter of which secretes a viscous polymer, in a shallow layer of soil packed in a column. More than 70% of the Pseudomonas sp. NRRL B-12227 cells were co-immobilized with the B. subtilis in a 7.5 cm layer of the packed soil by self-aggregation. More than 60% of the 1 mM cyanuric acid supplied to the packed soil was degraded in this layer during a 72 h period.

A case of isolated pancreatic metastasis of gastric cancer presenting problematic discrimination from gastropancreatic double cancer.

We experienced a case of isolated pancreatic metastasis caused by gastric cancer which showed high levels of the tumor markers relevant to pancreatic cancer. The patient was a 59-year-old man who had tumors in both the gastric antrum and pancreatic head. He was diagnosed as having double cancer of the stomach and pancreas on account of the high values of pancreatic cancer-associated markers, and underwent operation. This resulted in non-curable resection attributable to broad lymph node metastasis. The resected specimen lacked continuity between the pancreas tumor and gastric tumor, and the pancreatic tumor was histologically diagnosed as metastasis from the gastric cancer. Moreover, the advanced lymph vessel invasion suggested possible metastasis through the lymph ducts. The present case is a rare metastatic form because there has been no report of lymphogenous isolated pancreatic metastasis of gastric cancer. In advanced gastric cancer, the possibility of pancreatic metastasis should be always borne in mind, and pancreatic biopsy may be taken into account at times. Radical operation may be performed corresponding to the degree of each stage of the double cancer of stomach and pancreas. However, considering the low possibility of curable resection for pancreatic metastasis of gastric cancer, other treatments than surgery should also be considered.

Multiscale analysis of stress distribution in teeth under applied forces.

OBJECTIVES: The present study aimed to clarify stress distribution in teeth under an external applied load using microindentation and multiscale simulation. METHODS: Anisotropic material properties of enamel and dentin were measured using a microindentation method with a dynamic ultra microhardness tester. The numerical model was constructed using the finite element mesh superposition method with a microscale (enamel rods), mesoscale (teeth), and macroscale (bone). Multiscale simulation was used to analyze different scale structures. A concentrated load (10 N) was applied to the labial surface of the central incisor. RESULTS: The results revealed stresses of 5 MPa (normal stress) and 6.5 MPa (shear stress) in the enamel sheath at the center of the labial region compared to 1.4 MPa (normal stress) and 21.4 MPa (shear stress) in the cervical region. SIGNIFICANCE: These results suggest that shear stresses in the enamel sheath may play significant roles in stress transmission.

Randomized, controlled investigation of the anti-infective properties of the Alexis retractor/protector of incision sites.

BACKGROUND: We prospectively investigated whether the wound-protective Alexis (Applied Medical, Rancho Santa Margarita, CA) wound retractor was effective in preventing surgical site infection (SSI). METHODS: We examined the actual condition of SSI in a 12-month randomized, controlled trial consisting of 221 patients who had undergone nontraumatic gastrointestinal surgery. The patients were divided into a With Alexis retractor group (n = 111) and a Without Alexis retractor group (n = 110). We also analyzed SSI separately on the basis of surgical sites such as gastric surgery or colorectal surgery. RESULTS: Overall estimation showed a significant decrease in wound infection (superficial incisional SSI) in the With Alexis retractor group. In the analysis based on surgical sites, a significant decrease in wound infection was noted in the With Alexis retractor group, the members of which had undergone colorectal surgery. There was no significant difference between the two groups in the occurrence of organ/space SSI, including anastomotic leak or intraperitoneal abscess. CONCLUSION: It was suggested that the use of the Alexis wound retractor would protect surgical wounds from contamination by bacteria and thus prevent infection.