ABSTRACT
Objective:To compare the dosimetric difference between intensity-modulated photon radiaotherapy (IMRT) planning and intensity-modulated proton radiotherapy (IMPT) planning for glioma.Methods:The clinical data of 15 glioma patients who underwent IMRT in ion medical center of the First Affiliated Hospital of USTC from November 2020 to April 2022 were retrospectively analyzed. IMRT planning and IMPT planning were designed for the image of each patient in the therapy planning system. Main dosimetric parameters were compared including plan target volume (PTV), coverage index (CI), dose homogeneity index (HI), and maximal dose (D max) and mean dose (D mean) of organs at risk between both plans. Results:There were no significant differences between IMRT planning and IMPT planning in terms of D max and D mean of PTV1 and PTV2, CI and HI (all P > 0.05). Compared with IMRT planning, brainstem D mean [6.92 GyE (0.09 GyE, 12.58 GyE) vs. 24.41 GyE (2.59 GyE, 34.18 GyE)], left optic nerve D max [0.78 GyE (0.04 GyE, 25.18 GyE) vs. 20.42 GyE (6.38 GyE, 37.17 GyE)], left optic nerve D mean [0.10 GyE (0.01 GyE, 11.63 GyE) vs. 9.74 GyE (2.99 GyE, 20.87 GyE)], right optic nerve D mean [1.57 GyE (0.13 GyE, 14.90 GyE) vs. 14.08 GyE (2.66 GyE, 23.67 GyE)], left len D max [0 GyE (0 GyE, 2.91 GyE) vs. 4.84 GyE (1.42 GyE, 5.48 GyE)], left len D mean [0 GyE (0 GyE, 1.73 GyE) vs. 3.84 GyE (1.25 GyE, 4.30 GyE)], right len D max [0.25 GyE (0.04 GyE, 4.55 GyE) vs. 4.28 GyE (1.58 GyE, 5.84 GyE)], right len D mean [0.16 GyE (0.01 GyE, 1.95 GyE) vs. 3.73 GyE (1.04 GyE, 4.86 GyE)], pituitary D max [6.97 GyE (0.18 GyE, 39.70 GyE) vs. 36.60 GyE (2.74 GyE, 45.19 GyE)], pituitary D mean [1.36 GyE (0.06 GyE, 13.85 GyE) vs. 24.74 GyE (2.42 GyE, 32.80 GyE)], hippocampus D max [5.10 GyE (0.24 GyE, 26.52 GyE) vs. 35.83 GyE (5.03 GyE, 46.11 GyE)], hippocampus D mean [0.36 GyE (0.04 GyE, 25.65 GyE) vs. 18.79 GyE (2.37 GyE, 28.10 GyE)] in IMPT planning were lower, and the differences were statistically significant (all P < 0.05). There were no statistical differences in brainstem D max [51.98 GyE (0.66 GyE, 53.43 GyE) vs. 53.29 GyE (3.87 GyE, 53.48 GyE)], right optic nerve D max [9.60 GyE (0.01 GyE, 43.32 GyE) vs. 25.37 GyE (3.45 GyE, 41.25 GyE)] of both plans (all P > 0.05). Conclusion:In the radiotherapy for glioma, IMRT and IMPT can meet the dose demand in clinic. Furthermore, IMPT planning can protect organs at risk and reduce radiation dose in hippocampus, brainstem, optic nerve, lens and pituitary.
ABSTRACT
Objective:To investigate the impacts of the composition and physical density of tissue on the dose distribution of implanted 125I seeds, in order to provide references for the clinical dose calculation and assessment of implanted radioactive particles. Methods:The OncoSeed 6711 physical model of 125I seeds was established using thes of twareegs_brachy and was validated through the calculation of dose rate constant and the radial dose function [ g( r)] in water. Then, based on the element composition and physical density of different types of tissue, the g( r) and absorbed dose ratein water, prostate, breast, muscle, and bone were calculated. Results:The calculated dose rate constant (0.950 cGy·h -1·U -1) and g( r)in water approached the values in related literature. The absorbed dose in bone was 6.042 times than that in water at a distance of 0.05 cm from the implanted source. The difference between the absorbed doses in breast and water was more than 10% at a distance of less than 1.7 cm from the implanted source. The difference between the absorbed doses in prostate/muscle and water was less than 5% at the same radial location. Conclusions:The dose distribution of 125I seeds in some types of human tissue is significantly different from that in water, which should be carefully considered in clinical dose calculation.
ABSTRACT
Objective:To evaluate the impacts of tissue heterogeneity on dose calculation of cervical brachytherapy by comparing the doses calculated by two clinically used dose calculation method and the CT image-based Monte Carlo (MC) method.Methods:This study retrospectively selected 11 patients with cervical cancer treated with 3D brachytherapy in Anhui Provincial Cancer Hospital from January 2018 to June 2020. The dose distribution of each plan was calculated via three methods, dose calculation method described in American Association of Physicist in Medicine(AAPM) Task Group No. 43 Report (TG43-BT), Acuros BV(BV-BT) used to perform accurate dose calculations in high-dose-rate (HDR) brachytherapy with phantom heterogeneity, and CT image-based EGSnrc tool kit used to perform Monte Carlosimulation (MC-BT). The dose volumes( V3 Gy, V6 Gy, V9 Gy, and V12 Gy), target volume doses( D98, D90, D50), D2 cm 3 of organs at risk (OARs) calculated by the three methods were compared. Results:The HRCTV D90obtained by TG43-BT was 6.274 Gy, which was even overestimated by around 5% compared to the result calculated by MC-BT. Meanwhile, TG43-BT overestimated the dose volumesand the target volume doses compared to MC-BT.Except for D50 and V12 Gy, the differences between the doses to tumor calculated by BV-BT and MC-BT were not statistically significant( P>0.05). There was also no significant statistical difference between the D2 cm 3 of rectum, small intestine, and sigmoid calculated by BV-BT and MC-BT ( P>0.05). In contrast, the dose to D2 cm 3 of bladder determined by MC-BT was 4.609 Gy, which was notably higher than those deter mined by TG43-BT and BV-BT. Conclusions:TG43-BT overestimated the doses to tumor targets and most OARs since the effects of tissue heterogeneity were not taken into consideration. BV-BT performed efficient calculation and most of the dose distributionin target volume and OARs obtained by BV-BT were consistent with that calculated by MC-BT. Nevertheless, low accuracy occurred for the regions near the sources and full bladder, which warrants further caution in clinical evaluation.
ABSTRACT
Objective:To investigate the dosimetry differences in the treatment of locally advanced cervical cancer with intracavitary/interstitial brachytherapy (IC/IS BT), intracavity brachytherapy combined with intensity modulated radiotherapy (ICBT+ IMRT) and simple IMRT.Methods:Totally 16 patients with local advanced cervical cancer were retrospectively selected, which were treated by three-dimensional brachytherapy. On the basis of the original three-dimensional intracavitary/interstitial brachytherapy plan, ICBT+ IMRT and IMRT plans were designed respectively to study the dosimetry differences of target and different organs at risk for the three kinds of plans.Results:A total of 75 brachytherapy treatment plans were designed, including 25 IC/IS BT, 25 ICBT+ IMRT and 25 IMRT. There was not statistically significant difference of target dose parameters between ICBT+ IMRT and IC/IS BT plan ( P>0.05). ICBT+ IMRT plans had better OAR sparing than IC/IS BT. The doses of OARs in the IMRT plans were relatively large and the volume irradiated to more than 60 Gy ( V60) was significantly higher( t=6.77, 10.37, 4.61, 2.83, P<0.05). Conclusions:The ICBT+ IMRT technique not only provides better target coverage, but also maintains low doses to the OARS, which can be used as an alternative treatment to IC/IS BT. Although the target coverage of IMRT is better, the protection of OARs is not satisfied, so it is not suitable for local boost therapy of advanced cervical cancer.
ABSTRACT
Objective To study the dosimetric parameters of Varian GammaMed Plus HDR 192 Ir source via Monte Carlo ( MC ) method based on the recommendation of the American Association of Physicist in Medicine ( AAPM) and European Society for Radiotherapy and Oncology ( ESTRO) . Methods Using the Monte Carlo program EGSnrc, an accurate model of 192 Ir source for MC calculations was establish firstly. Through formula derivation, bilinear interpolation and unit conversion, the air kerma strength per unit source activity, the dose rate constant, radial dose function and anisotropy function was obtained then , and compare the result with those in other published studies. Results The air kerma strength per unit source activity was 9. 781 × 10-8 U/Bq. The dose rate constant was 1. 113 cGy · h-1 · U-1 , with a discrepancy of less than 0. 4％ compared with result published in other works. Furthermore, the curves of radial dose function and anisotropy function overall agree with the data shown in the literature. Conclusions The feasibility of performing dosimetric studies of 192 Ir source using the MC software EGSnrc was demonstrated. This work provides a theoretical guidance on analysis of the dose distribution of brachytherapy and on evaluation of the dose accuracy of clinical radiotherapy.
ABSTRACT
Objective To understand the situation of college students' awareness about innovative credit, analyze the influencing factors, in order to provide a scientific basis for constructing innovation credits and promoting the double strategy. Method The undergraduates of a medical university who were still at school in April 2015 were selected, and by using a stratified cluster sampling method, 450 students were chosen to be conducted by self-administered questionnaire survey to understand the cognitive status of in-novation of credit system in college students. Chi square test was used to compare the passing rates of students in different demographic characteristics, and the relationship between scores was analyzed by linear regression analysis. Result A total of 439 valid questionnaires were collected , and the total scores of innovative knowledge, attitudes and behaviors of 439 undergraduates were 15.95％ (70/439), 36.44％ (160/439) and 32.80％(144/439) respectively. In the part of knowledge innovation credits, girls' passing rate was higher than boys ( χ2=4.010,P=0.045. In the part of attitude, high grade group students had more positive attitude than the low grade group of students ( χ2=6.227,P=0.0013). In the part of behavior; higher grade students with innovative credits had higher pass rates than those in lower grades (chi, 2=7.781, P=0.005), and boys had a higher rate of passing than girls ( χ2=6.658,P=0.010). The total score of knowledge was positively linear with the total score of attitude and behavior. Conclusion College Students' awareness of innovation credit rate is low, but the innovative attitude and behavior is positive. The higher the awareness rate is conducive to the cultivation of attitude and behavior, so it is necessary in medical colleges to carry out innovation of credit and promote the cultivation of innovative consciousness.
ABSTRACT
Objective To investigate the relationship between the single nucleotide polymorphisms (SNP) of rs1008438 in HSP70 promoter and the susceptibility of high altitude pulmonary edema (HAPE) .Methods The PCR‐DNA sequencing method was used to analyze gene distribution of rs1008438 in 100 HAPE patients and 200 healthy people ,and the relationship between dif‐ferent genotypes and HAPE was evaluated .Meanwhile ,HSP70 protein in cytoplasm and nuclei of white blood cells were detected by ELISA in patientgroup and healthy group .TNF‐α,IL‐1β and IL‐6 levels were analyzed by protein chip technology and EVI‐DENCE180 automatic chip reader .Results The TT ,GT ,and GG genetype frequencies of rs1008438 in HAPE patients and healthy controls were 76 .0% ,20 .0% ,4 .0% ,and 93 .0% ,6 .5% ,0 .5% ,respectively .The TT genetype frequency in HAPE patients was significantly lower than that in healthy control(P<0 .05) .The HAPE incidence rate in GT/GG genetype was 4 .195 times higher than that in TT genetype ,and the allele G can also significantly increase the prevalence of HAPE compared to T allele (OR=4 .178) .ELISA showed that HSP70 were higher in HAPE group of all genotypes than those in healthy control of the same geno‐type .And the nuclei/cytoplasm ratio of HSP70 in TT genotype was higher than that in GT/GG genotype .Protein chip showed that the levels of TNF α,IL‐1β,and IL‐6 in HAPE group were significantly higher than those in healthy control .Conclusion The poly‐morphism of rs1008438 is related to susceptibility of HAPE .Mutate genetype may change the promoter activity and increase the ex‐pression of HSP70 ,which induced HAPE .
ABSTRACT
Objective To investigate the expression of sialic acid-binding immunoglobulin-like lectin-1 (Siglec-1) in the peripheral blood mononuclear cells (PBMCs) in patients with rheumatoid arthritis (RA),osteoarthritis (OA) and healthy controls and to explore the relationship between Siglec-1 expression and disease activity in RA.Methods Siglec-1 protein and mRNA levels were measured by flow cytometry and real-time quantitative reversetranscription-polymerase chain reaction (qRT-PCR) in 42 RA patients,28 OA patients and 26 healthy controls,respectively.The correlation studies between Siglec-1 and disease activity score 28 (DAS28) or C-reactive protein were performed.T-test was used for comparisons between groups and Pearson's correlation test was used for correlation analysis.Results The percentage of Siglec-1 positive cells of PBMCs in RA group [(15.2±7.6)％] was significantly higher than that in the OA group [(2.3 ±2.6)％] or healthy controls [(2.1±1.6)％,t=8.615,8.661; all P＜0.01].And the major cell type in PBMCs that expressed Siglec-1 was monocytes.The relative Siglec-1 mRNA expression in PBMCs in the RA group (3.4±1.5) was also significantly higher than that in the OA group (1.2±0.4) or healthy controls [(1.0± 0.4),t=3.446,3.966; all P＜0.05].But no significant differences of Siglec-1 protein and mRNA between the OA group and healthy controls were found.Furthermore,positive correlations between Siglec-1 protein and DAS28 or hs-CRP were found in RA patients (r=0.89,P＜0.01; r=0.48,P＜0.01).Conclusion PBMCs are activated which are characterized by elevated expression of Siglec-1 in RA patients.Circulating Siglec-1 may be considered as a potential noninvasive biomarker for monitoring disease activity in RA.