Using 1,2 dimethylimidazole to improve gel thermalstability for wellbore plugging in ultra-high temperature fractured reservoirs

Working fluid loss as well as formation damage is usually encountered as a big challenge during well completion and workover for fossil-fuel production. Polymer gel is widely used for wellbore plugging to isolate the working fluid and the reservoir for controlling fluid loss and protecting the reservoir. However, with the increasing number of ultra-high temperature well (>180 °C) operations, the thermal stability of the gel plug is increasingly required. In this paper, 1,2 dimethylimidazole (C5H8N2) is first used to prepare a gel plug. The effects of C5H8N2 on gel gelation at dynamic heating mode, viscosity, elasticity, thermal stability and temporary plugging performances are evaluated at 190 °C. It is found that the addition of C5H8N2 does not affect the gelation, while a slightly viscosity-reducing effect is exhibited. At 190 °C, the gel without C5H8N2 broke down within 4 hours and lost its temporary plugging performance, while the gel with 20% imidazole remained unbroken after 60 hours. For the fractured core (5 cm in length) plugging experiments, the addition of 15% C5H8N2 significantly increased the breakthrough pressure of gels from 0.2 MPa to 1.9 MPa compared to pure gels (without C5H8N2). The enhancement mechanism of C5H8N2 is investigated. Recommendations for the application of gels with C5H8N2 are given in the paper. This paper provides an avenue for the development of gel plug to deal with wellbore temporary plugging jobs in ultra-high temperature fractured reservoirs.</p

A practical method to improve the performance of knowledge-based VMAT planning for endometrial and cervical cancer

The aim of this work was to demonstrate a practical and effective method to improve the performance of RapidPlan (RP) model. 203 consecutive clinical VMAT plans (P0) for cervical and endometrial cancer were used to train an RP model (M0). The plans were then reoptimized by M0 to generate 203 new plans (P1). Compared with P0, 150 plans with a lower mean dose (MD) of bladder, rectum and PBM were selected from P1 to configure a new RP model (M1). A final RP model (M2) was trained using plans in M1 and the remaining 53 plans from P1 (excluding OARs with worse MD) and the corresponding plans from P0 (only including OARs with better MD). The models were validated on the mentioned 53 plans (closed-loop set) and 46 patient cohorts outside the training library (open-loop set). p  For closed-loop validation, the difference of D2%, D98% and CI95% between groups was of no statistical significance, the homogeneity index (HI) was lower in the groups of RP models (p 0, M1 and M2, except the MD of bowel in M1 and MD of LFH in M2. Similarly, for open-loop validation, there was no significant difference in D2%, D98% and HI between groups, but CI95% was larger in the clinical group (p 0, M1 and M2, with the exception of bowel in M1. The practical method of incorporating plan data of better-sparing OARs from both the clinical VMAT plans and the re-optimized plans could further improve the performance of the RP model.</p

DataSheet_1_A study on the radiomic correlation between CBCT and pCT scans based on modified 3D-RUnet image segmentation.docx

PurposeThe present study is based on evidence indicating a potential correlation between cone-beam CT (CBCT) measurements of tumor size, shape, and the stage of locally advanced rectal cancer. To further investigate this relationship, the study quantitatively assesses the correlation between positioning CT (pCT) and CBCT in the radiomics features of these cancers, and examines their potential for substitution.MethodsIn this study, 103 patients diagnosed with locally advanced rectal cancer and undergoing neoadjuvant chemoradiotherapy were selected as participants. Their CBCT and pCT images were used to divide the participants into two groups: a training set and a validation set, with a 7:3 ratio. An improved conventional 3D-RUNet (CLA-UNet) deep learning model was trained on the training set data and then applied to the validation set. The DSC, HD95 and ASSD were calculated for quantitative evaluation purposes. Then, radiomics features were extracted from 30 patients of the test set.ResultsThe experiments demonstrate that, the modified model achieves an average DSC score 0.792 for pCT and 0.672 for CBCT scans. 1037 features were extracted from each patient’s CBCT and pCT images, 73 image features were found to have R values greater than 0.9, including three features related to the staging and prognosis of rectal cancer.ConclusionIn this study, we proposed an automatic, fast, and consistent method for rectal cancer GTV segmentation for pCT and CBCT scans. The findings of radiomic results indicate that CBCT images have significant research value in the field of radiomics.</p

Absolute differences in the heart between the perturbed and the original plans.

Absolute differences in the heart between the perturbed and the original plans.</p

Underdosed volumes in CTV (red) in VMAT-5B (orange) and VMAT-10B (dark green) with setup errors in the inferior direction for a typical patient.

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Dosimetric comparison between VMAT-5B and VMAT-10B for the OARs.

Dosimetric comparison between VMAT-5B and VMAT-10B for the OARs.</p

Data_Sheet_1_How do moral hazard behaviors lead to the waste of medical insurance funds? An empirical study from China.docx

ObjectiveThe huge loss of health insurance funds has been a topic of concern around the world. This study aims to explore the network of moral hazard activities and the attribution mechanisms that lead to the loss of medical insurance funds.MethodsData were derived from 314 typical cases of medical insurance moral hazards reported on Chinese government official websites. Social network analysis (SNA) was utilized to visualize the network structure of the moral hazard activities, and crisp-set qualitative comparative analysis (cs/QCA) was conducted to identify conditional configurations leading to funding loss in cases.ResultsIn the moral hazard activity network of medical insurance funds, more than 50% of immoral behaviors mainly occur in medical service institutions. Designated private hospitals (degree centrality = 33, closeness centrality = 0.851) and primary medical institutions (degree centrality = 30, closeness centrality = 0.857) are the main offenders that lead to the core problem of medical insurance fraud (degree centrality = 50, eigenvector centrality = 1). Designated public hospitals (degree centrality = 27, closeness centrality = 0.865) are main contributor to another important problem that illegal medical charges (degree centrality = 26, closeness centrality = 0.593). Non-medical insurance items swap medical insurance items (degree centrality = 28), forged medical records (degree centrality = 25), false hospitalization (degree centrality = 24), and overtreatment (degree centrality = 23) are important immoral nodes. According to the results of cs/QCA, low-economic pressure, low informatization, insufficient policy intervention, and organization such as public medical institutions, were the high-risk conditional configuration of opportunism; and high-economic pressure, insufficient policy intervention, and organizations, such as public medical institutions and high violation rates, were the high-risk conditional configuration of risky adventurism (solution coverage = 31.03%, solution consistency = 90%).ConclusionThere are various types of moral hazard activities in medical insurance, which constitute a complex network of behaviors. Most moral hazard activities happen in medical institutions. Opportunism lack of regulatory technology and risky adventurism with economic pressure are two types causing high loss of funds, and the cases of high loss mainly occur before the government implemented intervention. The government should strengthen the regulatory intervention and improve the level of informatization for monitoring the moral hazard of medical insurance funds, especially in areas with low economic development and high incident rates, and focus on monitoring the behaviors of major medical services providers.</p

Dosimetry of the targets and OARs for the patients with perturbed plans.

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Schematic diagram showing the planning target volume (PTV) and beam arrangements for a representative patient.

A, the two continuous ~240° arcs that start at 300 ~ 305° and stop at 170 ~ 179° for lymph nodes in SCF; B, the four split sub-arcs obtained by splitting two ~240° arcs at 30° for the chest wall.</p

Absolute differences in CTV between the perturbed and original plans.

Absolute differences in CTV between the perturbed and original plans.</p