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BackgroundWith the rapid development of nuclear energy and the wide application of nuclear technology, the radioactivity level of bodies of water has become a highly concerning issue for the public and governments, especially after the Fukushima nuclear accident in Japan.PurposeThis study aims to develop an online γ radioactivitymonitoring system based on 4G Remote Terminal Unit (4G-RTU) to meet the needs of online and emergency monitoring of water radioactivity.MethodsFirst, the γ-ray monitoring device based on sodium iodide detector, 4G-RTU, an integrated power supply waterproof and compression resistant floating device and corresponding software were employed to compose an online monitoring. Second, Qt programming control software was used to realize the remote control of the system, real-time radioactivity monitoring, and data upload. Finally, the original data obtained by the system were used to test the performance indicators, applicability, accuracy, and software functions to verify the practicability of the system.ResultsWithin the coverage of the 4G network, the system realizes remote control of equipment, real-time online monitoring, and data upload throughout the day. The detectable energy range of the system is 30~3 000 keV, and the energy resolution of the system for 137Cs at 662 keV is 7.3% with minimum detectable activity of 0.75 Bq∙L-1. The spectral drift for 208Tl at 2 614 keV is 0.33%, and the linearity of the spectral energy is 0.999 970. The maximum value of energy spectrum stability is 2.28% for 7 h continuous operating, and the minimum value is -2.36%. The operating temperature range of the system is in the range of -5 ℃ to +50 ℃.ConclusionsThe on-line monitoring system meets the application demand and achieves the expected function. It has important popularization value and application prospects in the field of online radioactive monitoring of bodies of water such as oceans, lakes, and rivers.

Background: Venous tumor thrombus (VTT) consistency of renal cell carcinoma (RCC) is an important consideration in nephrectomy plus thrombectomy. However, evaluation of VTT consistency through preoperative MR imaging is lacking. Purpose: To evaluate VTT consistency of RCC through intravoxel incoherent motion‐diffusion weighted imaging (IVIM‐DWI) derived parameters (Dt, Dp, f, and ADC) and the apparent diffusion coefficient (ADC) value. Study Type: Retrospective. Population: One hundred and nineteen patients (aged 55.8 ± 11.5 years, 85 male) with histologically‐proven RCC and VTT who underwent radical resection. Field Strength/Sequences: 3.0‐T; two‐dimensional single‐shot diffusion‐weighted echo planar imaging sequence at 9 b‐values (0–800 s/mm2). Assessment: IVIM parameters and ADC values of the primary tumor and the VTT were calculated. The VTT consistency (friable vs. solid) was determined through intraoperative findings of two urologists. The accuracy of VTT consistency classification based on the individual IVIM parameters of primary tumors and of VTT, and based on models combining parameters, was assessed. Type of operation, intra‐operative blood loss, and operation length were recorded. Statistical Tests: Shapiro–Wilk test; Mann–Whitney U test; Student's t‐test; Chi‐square test; Receiver operating characteristic (ROC) analysis. Statistical significance level was P < 0.05. Results: Of the enrolled 119 patients, 33 patients (27.7%) had friable VTT. Patients with friable VTT were significantly more likely to experience open surgery, have significantly more intraoperative blood loss, and significantly longer operative duration. The area under the ROC curve (AUC) values of Dt of the primary tumor and VTT in classifying VTT consistency were 0.758 (95% CI 0.671–0.832) and 0.712 (95% CI 0.622–0.792), respectively. The AUC value of the model combining Dp and Dt of VTT was 0.800 (95% CI 0.717–0.868). Furthermore, the AUC of the model combining Dp and Dt of VTT and Dt of the primary tumor was 0.886 (95% CI 0.814–0.937). Conclusion: IVIM‐derived parameters had the potential to predict VTT consistency of RCC. Evidence Level: 3 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]