[en] This paper presents a new secondary loop of nuclear power plant system, including the main components of turbine, condenser, feed pump, and heater, with RELAP5 code. The research of the single component model adaptive authentication analysis and the local computing ability of the code have been studied. The results show that the steady state calculation results of the RELAP5 code are basically consistent with the design value, and the dynamic calculations are also able to meet the calculation accuracy request of the main components in secondary loop. (authors)

[en] Objective: To evaluate the value of whole-body DWI (WB-DWI) in bone metastasis. Methods: WB-DWI was performed on 10 healthy volunteers and 35 patients with bone metastasis. WB-DWI and ECT was performed in all 35 patients to detect bone metastasis and compared the result between two methods with a chi-square test, P<0.05. Results: (1) Background tissue was suppressed in WB-DWI, fat, muscle, vessels and liver appeared the same as background. Skeleton showed medium or slightly lower signal. Lymph nodes, some glandular organs, kidneys were showed medium signal. Spleen, testicle, brain tissue were low signal, bladder, gallbladder were depicted as low signal because of 'T₂ through' effect. Bone metastasis were multitude and inequality of size, punctiform, nodosity, or column low intensity. (2) Concordance between WB-DWI and ECT was seen only in 4 case, while in total WB-DWI displayed 1 bone metastasis on skull, 46 on rib and sternum, 3 on scapula, 4 on extremities, 83 on vertebral, 36 on pelvic bone. ECT showed 2 bone metastasis on skull, 62 on rib and sternum, 7 on scapula, 9 on extremities, 64 on vertebral, 19 on pelvic bone. WB-DWI was recognizable for 74% bone metastasis on rib and sternum, ECT was 77%, 53% for vertebral and pelvic bone (P<0.05). Total distribution probability varied for metastasis of different location. Conclusion: WB-DWI was a sensitive method for' screening bone metastasis. (authors)

[en] Objective: To investigate the value of kinetic features measured by computer-aided diagnosis (CAD) for breast MRI. Methods: One hundred and sixty four lesions diagnosed pathologically by operation or biopsy comprised the analysis set. Automated lesion kinetic information from CADStream programs for breast MRI was identified. Three CAD variables were compared for benign and malignant lesions: initial phase peak enhancement (greatest percentage of signal intensity increase on first contrast enhanced sequence), delayed phase enhancement categorized by a single type of kinetics comprising the largest percentage of enhancement (washout, plateau, or persistent), and delayed phase enhancement categorized by single most suspicious type of kinetics (any washout > any plateau > any persistent). Morphological characteristics of breast lesions were described according to breast imaging and reporting data system (BI-RADS). Initial phase peak enhancement mean values between benign and malignant breast lesions were compared by using Wilcoxon rank-sum test, delayed phase enhancement categorized by a single type of kinetics comprising the largest percentage of enhancement or by single most suspicious type of kinetics between benign and malignant breast lesions were compared by using Chi-square test. Results: There were 72 benign and 92 malignant breast lesions. A total of 123 (75.0%) mass lesions were identified,and the other 41 (25.0%) lesions showed no mass. Thirty lesions were BI-RADS-MRI 2, 68 lesions were BI-RADS-MRI 3, 43 lesions were BI-RADS-MRI 4, 23 lesions were BI-RADS-MRI 5. Initial phase peak enhancement mean values of benign and malignant lesions were 237% (69% to 629%) and 336% (86% to 793%), respectively. There was no significant difference between benign and malignant lesions in initial peak enhancement mean value (Z=-1.626, P=0.104). Delayed phase enhancement categorized by single most suspicious type of kinetics (any washout > any plateau > any persistent) for benign and malignant lesions were 15, 10, 47 and 2, 3, 87 respectively. There was a significant difference between benign and malignant lesions (χ"2=23.562, P=0.000). Initial peak enhancement value < 100% or ≥100% were 5 and 67 for benign lesions, 3 and 89 for malignant lesions, respectively. There was no significant difference between benign and malignant lesions at 100% threshold (χ"2=1.181, P=0.277). Delayed phase enhancement categorized by a single type of kinetics comprising the largest percentage of enhancement (washout, plateau, or persistent) for benign and malignant lesions were 48, 6, 18 and 47, 15, 30 respectively.There was no significant difference between benign and malignant lesions (χ"2=4.496, P=0.106). Conclusions: Of CAD kinetics analyzed,only delayed enhancement categorized by most suspicious type is helpful for the differentiation between benign and malignant lesions. However, there is significant overlap between initial peak enhancement at 100% threshold or delayed kinetics categorized by largest percentage enhancement types of benign and malignant lesions, so lesion morphologic features should be considered. (authors)

[en] Objective: To evaluate multiple magnetic resonance (MR) imaging techniques in the differentiation of benign and malignant soft tissue tumors by comparing different information from MR perfusion-weighted Imaging (MR-PWI) and ¹HMR spectroscopy (¹H-MRS). Methods: Forty patients with soft tissue tumors underwent conventional MR imaging, dynamic contrast-enhanced T₂^*-weighted MR-PWI and ¹H proton MR spectroscopy. The differences of perfusion and ¹H-MRS parameters of benign and malignant tumors were analyzed with t test. Results: There was significant difference between benign and malignant tumoral tissues of BF value and Cho/Cr ratio (t=2.531, 2.927, P<0.05), while BV, MTT, Cho, Cr or Lip peak value were not. TIC was different between benign group (Ib) and malignant group (Ia). When the threshold value of BF was 4.35 ml·100 mg^-1·min^-1, sensitivity and specificity for determining malignant tumors were 81.8% (18/22), 72.2% (13/18), respectively. When the threshold value of Cho/Cr ratio was 3.22, Sensitivity and specificity for determining malignant tumors were 86.4% (19/22), 88.9% (16/18), respectively. The abnormal wave crest is detected at 2.0-2.1 ppm in 5 malignant tumors (2 malignant schwannoma and 3 malignant fibrous histiocytoma), while the other 55 cases were not. Conclusion: The BF value and Cho/Cr ratio were both valuable diagnostic parameters in differentiating benign and malignant soft tissue tumors. TIC was helpful to distinguish malignant tumors from benign tumors, while the sensitivity and specificity of ¹H-MRS in diagnosing malignant soft tissue tumors were both higher. (authors)

[en] Purpose: To assess the reliability of dual-energy CT (DECT) spectral imaging for the differentiation of bone metastases (BMs) from Schmorl's nodes (SNs) in the vertebrae of cancer patients. Materials and methods: In this retrospective study, 102 cancer patients who underwent DECT (GE spectral CT Discovery CT750 HD scanner) had 110 low density vertebral lesions. Each lesion was characterized as a BM or SN, based on the typical MRI or SPECT/PET-CT findings as well as size and number change in the 6 months follow-up. The means of 140 kVp polychromatic CT values, 40–140 keV monochromatic CT values, slopes (k) of the spectral curves, bone(water) and water(bone) densities of BMs and SNs were measured and compared with independent-samples t-test. The difference values of the two lesions and their respective normal bone tissue were calculated (normal density − lesion density) and compared using independent-samples t-test. ROC curves were used to compare the diagnostic efficacies of these measures in the identification of SNs and BMs. Results: 110 lesions consisting of 69 BMs and 41 SNs were identified. The spectral curve patterns and slopes for BMs and SNs were different (p < 0.05). The water(bone) density of BMs (1009.02 ± 59.25 mg/cm"3) was higher than that of SNs (892.00 ± 83.65 mg/cm"3) (p < 0.01) while the bone(water) density (43.57 ± 50.87 mg/cm"3) was lower than that of SNs (174.60 ± 94.61 mg/cm"3) (p < 0.01). The 40 keV CT value, k, bone(water) density and water(bone) density had a higher diagnostic efficacy for differentiating the two lesions than polychromatic CT value (p < 0.05). Conclusions: Dual-energy CT imaging is accurate enough for identification of osteolytic metastases and Schmorl's nodes

[en] Objective: To assess the diagnostic value of MSCT and MR perfusion in the differentiation of benign and malignant soft tissue tumors. Methods: Twenty-six patients with soft tissue tumors were studied in MSCT perfusion and 29 patients in MR perfusion. The differences of perfusion parameters of benign and malignant tumors were analyzed. Results: The average value of MSCT BF was (24.49 ± 14.49) ml·100 mg^-1 · min^-1 for malignant group, and (1.98 ± 1.19) ml·100 mg^-1 · min^-1 for benign group. PS was (14.64 ± 1.89) ml·100 mg^-1·min^-1 for malignant group, and (2.40 ± 0.38) ml·100 mg^-1·min^-1 for benign group. The mean BF and PS in benign and malignant tumors had significant difference in MSCT perfusion. The sensitivity , specificity, accuracy, positive predictive value, and negative predictive value of MSCT in estimating the potential malignancy of the tumors were 90.9%(10/11), 86.7%(13/15), 88.5%(23/26), 83.3%(10/12), and 92.9%(13/14), respectively. The average value of MR BF was (0.11 ± 0.02) ml·100 mg^-1·min^-1 for malignant group, and (0.07 ± 0.01) ml·100 mg^-1·min^-1 for benign group. The mean BF in benign and malignant tumors has significant difference in MR perfusion. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of MR in estimating the potential malignancy of the tumors were 91.7%(11/12), 88.2%(15/17), 89.7%(26/29), 84.6%(11/13), and 93.8%(15/16), respectively. Conclusion: MSCT and MR perfusion are very helpful in the differentiation of benign soft tissue tumors from malignant ones. (author)

[en] Objective: To assess the diagnostic potential of MR- PWI and MR-DWI in differentiating benign from malignant bone tumors. Methods: MR- PWI and MR- DWI were performed on 39 patients by using GE Signa 1.5 T MR imager. The perfusion imaging was started with GRE- EPI sequence, signal intensities were measured on delineated ROI and TIC was gotten using the Functool 2 software system Type of TIC, signal decreasing in first- pass period, maximum slope of TIC and signal difference between two standard states were compared between benign and malignant bone tumors MR-DWI was performed with SE-EPI fast scan sequence with diffusion in three directions ADC values were obtained and compared on delineated ROI using the Functool 2 software system. The resultant data were analyzed with software (SPSS, version 13.0). Subjective overall performance of two techniques was evaluated with Receiver Uperating Characteristic (ROC) analysis. Results: 1.MR-PWI: 1.The patterns of TIC of most benign bone tumors (17/21) were type Ⅰ and Ⅱ, and that of all malignant bone tumors were type Ⅲ and Ⅳ. 2.There were significant differences in signal decreasing in first- pass period [(17.52±.37)% vs. (52.42±5.74)%], maximum slope of TIC [(4.69±2.84)% s"-"1 vs. (9.63±4.05)%·s"-"1] and signal difference between two standard states [(6.87±3.34)% vs. (31.75±1.09)%] between benign and malignant groups. And their diagnostic accuracy was 82.1%, 79.5% and 87.2% respectively. 3. 4 highly vascularized benign bone tumors were mistaken in diagnosis as malignant ones according to their perfusion characteristics. 2. MR-DWI: There was significant difference between ADC of benign and malignant groups [(1.86±0.38)×10"-"3 mm"2/s vs. (1.44±0.26))×10"-"3 mm"2/s] when b value was 300 s/mm"3. The diagnostic accuracy was 79.5% when ADC value less than 1.63)×10"-"3 mm"2/s was considered as malignant ones. 3 The diagnostic accuracy of MR-PWI and MR-DWI were 89.7% and 79.5% respectively. Conclusion: MR-PWI is the better valuable technique than MR-DWI in differentiation benign from malignant bone tumors. To suspicious highly vascularized bone tumors. MR-PWI combining with MR-DWI lead to higher diagnostic accuracy. (authors)

[en] Objective: To evaluate MR diffusion-weighted imaging (DWI)and MR perfusion- weighted imaging(PWI) in differentiating benign from malignant soft tissue tumors by comparing the related parameters. Methods: Fifty patients with soft tissue tumors verified by pathology (benign 24, malignant 26) underwent DWI and dynamic contrast-enhanced T₂^*-weighted PWI. DWI and PWI data of benign and malignant soft tissue tumors were acquired at the workstation and their difference was analyzed with t-test. The diagnostic accordance rate was verified with x²-test. Subjective overall performance of two techniques were evaluated with receiver operating characteristic (ROC) analysis. Results: ADC values of benign and malignant tumors were (2.03±0.36) x 10^-3 mm²/s, (1.52±0.39) x 10^-3 mm²/s, respectively. The signal intensity decrease of them during the first-pass perfusion (SI_decrease) were (13.54 ± 3.37)%, (47.57 ± 5.21)%, respectively. The maximum linearity slope rate of TIC (SS_max) of them were (5.51 ± 2.54)%, (7.94 ± 3.33)%, respectively. There were significant differences between benign and malignant tumors of ADC value and SI_decrease (t=2.515, 2.938; P<0.05), while there was no significant difference in SS_max (t= 1.272,P>0.05). When the threshold of ADC value was 1.866 x mm²/s, sensitivity and specificity for determining malignant tumors were 84.6% (22/26)and 83.3% (20/24). When the threshold of SI_decrease was 40.33%, sensitivity and specificity for determining malignant tumors were 88.5% (23/26)and 75.0% (18/24). In type la of TIC, the proportion of benign soft tissue tumor was 3/24 and malignant tumor was 20/26. In type Ib, benign tumor was 14/24 and malignant tumor was 3/26. In type Ic, malignant tumor was 3/26. In type II, benign tumor was 7/24. The diagnostic accordance rate of DWI and PWI were 84.0% (42/50)and 82.0% (41/50), respectively. There was no significant difference between them (χ²=0.8, P>0.05). The accuracies of them were 81.7%, 83.6% respectively by the area under the ROC curve (AUC). The sensitivity of PWI in diagnosing malignant soft tissue tumors was higher. Conclusions: ADC value and SI_decrease are valuable diagnostic parameters in differentiating benign and malignant soft tissue tumors. The threshold of these parameters for diagnosing malignant soft tissue tumors are 1.866 x 10^-3 mm²/s and 40.33%, respectively. The type of TIC can help to distinguish malignant tumors from benign tumors, while the SS_max can not. The accuracies of DWI and PWI in the diagnosis of malignant soft tissue tumors are moderate. Compared with DWI, PWI should be selected firstly because of its higher sensitivity in diagnosing malignant tumors. (authors)

[en] We present a method to construct the wide-band achromatic metalens in full visible waveband. The metalens is accomplished via arrayed rectangular dielectric nanoblocks which can manipulate the electromagnetic waves to support focusing function. The research results indicate that the dielectric nanoblocks with different widths can achieve the phase shift, in addition, the lengths of the dielectric nanoblock provide an extra degree of freedom for realizing the control of the wavefront. Therefore, the double regulation functions of widths and lengths can realize dispersion compensation. Finally, we design and simulate an achromatic metalens through combining dielectric nanoblocks with varied widths and lengths, which can achieve wide-band achromatic focusing in the spectral range from 0.4 µ m to 0.8 µ m with high diffraction efficiency (about 69%–84%). The method may be applied as an effective solution of wide-band light manipulation in integrated optical systems. (paper)

[en] Two-phase flow instability has been researched in the past decades. The forced circulation vertical parallel narrow channel system under different flow conditions was performed by the best estimate system computer code RELAP5/MOD3.4. The instability of parallel channel system was studied. The results show that two-phase flow instability between multi-channels (FIBM) and flow excursion instability are two typical types of instability in parallel narrow channels. The process and inherent reason of flow excursion and FIBM in forced circulation parallel channel system were analyzed. The effects of main operating parameters on flow excursion instability were studied. (authors)