Objective To study positron yield quantitatively in different phantoms by means of PET imaging after high energy photon irradiation,and to investigate the feasibility of bio-dose verification by PET in high energy photon radiotherapy.Methods The phantoms (hydrogel,HDPE,inhomogeneous phantom) were scanned with PET 1 min later after exposure to 2,4,6,8 Gy dose with/using 25 and 50 MV photon irradiation.The positron account rates were recorded every minute in PET scanning process and then fitted to get the half-lives of yielded nuclides.Positron distribution in each phantom was compared with dose distribution to investigate the relationship between positron activity and dose delivered.Results The half-lives of nuclides yielded in hydrogel and HDPE were supposed to be 2.23 and 19.47 min,respectively by fitting results,which had negligible difference with half-lives of 11C (20.2 min) and 15O (2.08 min).The positron amounts induced by 50 MV photon in hydrogel and HDPE were 3.88 and 3.86 times that of 25 MV photon,and increased in proportion to dose delivered.Except for build-up region and cavity,activity distributions in depth and off-axis were similar to dose distribution.Conclusions The amount and distribution of positron induced by high energy photon are related to dose delivered,and it is feasible to do dose verification with PET imaging in high energy photon radiotherapy.

Objective To investigate the awareness of osteoporosis and its influential factors in middle-aged and older people. Methods By using self-designed questionnaire, 354 middle-aged and old people were investigated as to their awarness of osteoporosis in Chajiao street community in Guangzhou. Among them, 58 people were measured the bone density in the calcaneal bone by Ultrasound. Results The average score of the questionnaire was 9.46 ± 5.13, and the accuracy was 39.4%. In the diagnosis and treatment, the accuracy was just 17.8%. The diet (the accuracy in 54%) and sport (the accuracy in 50.3%) were good. The statistical analyses showed the linear relationship between the T value of bone density and the age (P = 0.021), between the T value and the score (P = 0.047). Wilcoxon rank sum test found that the T value between female and male was significantly different (Z = -3.749, P < 0.000). With multiple linear regression analysis, the T value had a linear correlation with the score (F = 4.224, P = 0.045) positively. Conclusions Currently, the awareness of osteoporosis in the middle-aged and old people was inadequate. To better prevent osteoporosis, the propogation of knowledge and guidance provided by clinicians in osteoporosis should be improved necessarily and emergently.

The schemes of dose fractionation play an important role in tumor radiotherapy. We used mathematical methods to describe the process of tumor cells evolution during radiotherapy, trying to find how the schemes of dose fractionation affect tumor cells. In clinical radiobiology, linear-quadratic (LQ) model is frequently used to describe radiation effects of tumor cells. We integrated LQ model with effect of oxygen, and with the phenomenon of repopulation and reoxygenation in the theory of radiation biology. While we considered the disappearing progress of doomed cells in tumor, we established the mathematical model of tumor evolution in radiotherapy. We simulated some common treatment schedules, and studied the change role of tumor cells during radiotherapy. These results can serve for the optimization of dose fractionation scheme based on tumor radiobiological characteristics.
Cell Growth Processes ; radiation effects ; Dose Fractionation ; Humans ; Models, Theoretical ; Neoplasms ; pathology ; physiopathology ; radiotherapy ; Radiobiology

Objective To study the clinicopathologic characteristics of triple-negative breast cancer (TNBC) and its value in the prediction of prognosis. Method In this study,500 cases of female breast cancers were examined immunohistochcmically for the TNBC. The clinicopathologic characteristics of the 243 TNBC cases were inspected. Results TNBC accounted for 17.6% (88/500) of the 500 breast cancers. The histological types of the TNBC included mainly infihrative ductal carcinoma, metaplastic carcinoma and medullar carcinoma. Among those, histological grade Ⅲ accounted for 72.7% (64/88) of all the TNBC and was more common than that in hormone receptor positive breast cancers (HR+ group ) and Her-2 overexpression breast cancers (Her-2 group)(P=0.000). The positive rates of CK5/6 and EGFR in the TNBC were 30.7% (27/88) and 34.1% (30/88), respectively. The positive rates of ERCC1 and KIT in the TNBC were 28.4% (25/88) and 34.1% (30/88), respectively, Both of which were higher than those in the HR + group and Her-2 group, respectively (P=0.032 and P=0.026). 3-year survival rate of the TNBC was 71.5% and it was lower than that of HR group (P=0.021) and not significantly different from that of Her-2 group (P=0.474). Conclusions TNBC is the breast cancer with high aggressive pathologic futures and poor prognosis. EGFR and ERCC1 expression were positive in a portion of TNBC cases.

The volume change of tumor during radiotherapy processes indirectly reflects the short-term efficacy and the quality of radiotherapy planning. We analyzed clinical data of radiotherapy using a mathematical model in our study. First, we selected eight esophageal carcinoma patients with only using 3DRT and conventional dose fractionation schemes. And then we observed and measured the change of tumor volume during the radiotherapy. Based on the LQ model, repopulation and re-oxygenation in 4Rs, and the kinetics of doomed tumor disintegration, we established the mathematical model of tumor evolution in radiotherapy. And then we used the model to analyze the clinical trial data about esophageal carcinoma with radiotherapy. It was proved that the results of the model almost coincided with the clinical trial data. According to the analysis results, we could get the related radiobiology parameters to estimate biological effective dose and repopulation of patients. The mathematical model could provide reference for assessment of prognosis and further scheme of treatment.
Algorithms ; Esophageal Neoplasms ; pathology ; radiotherapy ; Humans ; Models, Theoretical ; Radiotherapy Planning, Computer-Assisted ; methods ; Tumor Burden

OBJECTIVETo investigate the role of R-Spondinl in the activation of hepatic stellate cells (HSCs).

METHODSTwenty-four healthy male Kunming mice were randomly divided into the following two groups:fibrosis model group (n=16) and control group (n=8). Hepatic fibrosis was induced by subcutaneous injections of CC14 (20% in olive oil) at a dose of 5 ml/kg twice per week. After 10 weeks, the animals were sacrificed by CO(2) over-exposure and liver tissues were harvested.The protein and mRNA levels of R-Spondin1, alphat-SMA,and collagen I were examined by Western blot assay and real-time PCR respectively. Additionally,HSCs were isolated from the mice liver tissues to examine the time-series expression changes of R-Spondinl, alpha-SMA, and nuclear beta-catenin.TCF activity was analyzed by luciferase reporter assay.Moreover,HSCs were cocultured with recombinant R-Spondin1 and DKK1 to evaluate dose-response.

RESULTSR-Spondinl expression was significantly higher in the fibrosis model group than in the control group (protein level:3.16 ± 0.18 vs. 0.99 ± 0.16, t =13.31, P < 0.01; mRNA level:4.36 ± 0.26 vs. 0.98 ± 0.12, t =21.46, P < 0.01).The culture-activated mouse HSCs showed up-regulated TCF activity (5.33 ± 0.34 vs. non-activated: 1.03 ± 0.09, t =20.93, P < 0.01), nuclear beta-catenin expression (4.47 ± 0.21 vs. 0.97 ± 0.14, t =25.25, P < 0.01), and R-Spondin1 expression (protein level: 4.54 ± 0.18 vs. 1.04 ± 0.12, t =31.17, P < 0.01; mRNA level:5.13 ± 0.15 vs. 1.01 ± 0.16, t=38.06, P < 0.01). Exogenous stimulation of freshly isolated mouse HSCs with recombinant R-Spondin1 induced a dose-dependent increase in both TCF activity and the expression of nuclear beta-catenin and alphat-SMA. DKK1 down-regulated activities of factors in the WNT signaling pathway and repressed activation of HSCs. Conclusion R-Spondin1 may promote HSC activation by enhancing the canonical WNT signaling pathway.

Animals ; Down-Regulation ; Extracellular Matrix Proteins ; Hepatic Stellate Cells ; Liver Cirrhosis ; Male ; Mice ; RNA, Messenger ; Wnt Signaling Pathway ; beta Catenin

Breast Neoplasms ; metabolism ; pathology ; Female ; Humans ; Ki-67 Antigen ; genetics ; metabolism

Objective To design water-equivalent plastic scintillator detector for the measurement of absorbed dose in tumor radiotherapy.Methods The concentration of ZrO2to be doped in polystyrene was estimated according to the empirical formula,and then the Monte Carlo program Geant 4(GEometry And Tracking 4)was used to simulate the energy deposition and transport process of X-rays with different energies in water,solid water RW34(composed of 2.1 wt％TiO2doping polystyrene)and different concentrations of ZrO2particles doped in polystyrene.The dose and attenuation coefficients were compared among different materials at different depths of water.Results The doses at different depths and the attenuation coefficient of polystyrene(doped with about 0.4 wt％ZrO2nanoparticles)were much more consistent with those of water and even exhibit much better water-equivalence than RW34.Conclusions The simulation results provide the basis for the development of water-equivalent scintillator.

Objective:To reconstruct the three-dimensional (3D) dose distribution in radiotherapy based on the convolutional neural networks (CNN) through multi-perspective scintillation light processing.Methods:First, fluorescence images were captured from three orthogonal perspectives using a complementary metal-oxide-semiconductor (CMOS) imaging sensor. Then, the images were converted into 3D images, which were input to the trained CNN for dose reconstruction. Finally, the reconstructed doses in different fields were evaluated in terms of gamma pass rate, mean-square error (MSE), percentage depth dose (PDD), and cross beam profile (CBP). Additionally, as the CNN model, 3D-Unet was pre-trained on a virtual dataset.Results:With the 50% maximum dose of as the threshold and 3%/3 mm as the standard, the central-plane and stereo-mean gamma pass rates of all field reconstruction distributions were over 90%, with MSEs remained below 1%. Besides, the PDD and CBP curves showed MSEs below 1‰ and below 1%, respectively.Conclusions:The deep learning-based method for 3D dose reconstruction using scintillation light contributes to enhanced verification of instantaneous 3D relative dose based on plastic scintillation detectors.

Objective:To summarize the clinical characteristics of patients with coronavirus disease 2019 (COVID-19) infected with Delta variant, so as to provide further references for clinical diagnosis and treatment.Methods:A real-world study was conducted to analyze the characteristics of 166 COVID-19 patients infected with Delta variant at Guangzhou Eighth People’s Hospital, Guangzhou Medical University.Results:The study enrolled 5 asymptomatic cases, 123 non-severe cases (mild and moderate type), and 38 severe cases (severe and critical type). Among these patients, 69 (41.6%) were male and 97 (58.4%) were female, with a mean age of 47.0±23.5 years. Thirty-nine cases (23.5%) had received 1 or 2 doses of inactivated vaccine. The incidence of severe COVID-19 cases was 7.7% in 2-doses vaccinated patients, which was lower than that of 11.5% in 1-dose and 26.8% in unvaccinated patients. The proportion of severe cases in 2 dose-vaccinated patients was 7.7%, which was lower than that of 11.5% in 1-dose vaccinated patients and 26.8% in unvaccinated patients, but the difference was not significant ( P>0.05). The most common clinical symptom was fever (134 cases, 83.2%), and 39.1% of cases presented with high-grade fever (≥39 °C); other symptoms were cough, sputum, fatigue, and xerostomia. The proportion of fever in severe cases was significantly higher than that of non-severe cases (97.4% vs. 76.4%, P<0.01). Similarly, the proportion of severe cases with high peak temperature (≥39 ℃) () was also higher than that of non-severe cases (65.8% vs. 30.9%, P<0.01). The median minimal Cycle threshold (Ct) values of viral nucleic acid N gene and ORFlab gene were 20.3 and 21.5, respectively, and the minimum Ct values were 11.9 and 13.5, respectively. Within 48 h of admission, 9.0% of cases presented with decreased white blood cell counts, and 52.4% with decreased lymphocyte counts. The proportions of increased C-reactive protein, serum amyloid A, interleukin 6, and interleukin 10 were 32.5%, 57.4%, 65.3%, and 35.7%, respectively. The proportions of elevated C-reactive protein, serum amyloid A and interleukin-6 in severe cases were significantly higher than those in non-severe cases ( P<0.01). Logistic regression analysis showed that older age and higher peak temperature were associated with a higher likelihood of severe cases ( OR>3, 95% CI: 2-7, P<0.01). In terms of treatment, traditional Chinese medicine (TCM) was used in 97.6% of non-severe cases and 100% in severe cases. Other treatments included respiratory and nutritional support, immunotherapy (such as neutralizing antibodies and plasma of recovered patients). The median times from admission to progression to severe cases, of fever clearance, and of nucleic acid conversion were 5 days, 6 days and 19 days, respectively. No deaths were reported within 28 days. Conclusions:The symptoms of Delta variant infection in Guangzhou are characterized by a high proportion of fever, high peak temperature, long duration of fever, high viral load, a long time to nucleic acid conversion, and a high incidence of severe cases. The severe cases exhibit a higher percentage of elderly patients, a longer duration of fever and have a higher fever rate and a higher hyperthermia rate than non-severe cases. Age and hyperthermia are independent risk factors for progression to severe disease. The combination of TCM and Western medicine can control the progression of the disease effectively.