Objective To investigate the effects of volumetric modulated arc therapy (VMAT) with 6 MV and 10 MV X-ray photon energies in patients with cervical cancer. Methods From March 2019 to May 2020, 24 patients with cervical cancer who underwent radiation therapy in the Oncology Radiotherapy Department of our hospital were selected. VMAT plans with 6 MV and 10 MV photon energies were re-designed for each patient. The target parameters (D_98%, D_2%, D_mean), conformal index, and homogeneity index of the two groups were compared. The radiation doses received by the bladder, rectum, small intestine, left femoral head, right femoral head, and normal tissue other than planning target volume (Body-PTV), as well as monitor units and estimated total delivery time, were also compared. Results D_2%, D_mean, homogeneity index, and monitor units were significantly lower in the 10 MV group than in the 6 MV group (50.78 ± 0.33 Gy vs. 50.35 ± 0.29 Gy; 49.05 ± 0.2 Gy vs. 48.93 ± 0.17 Gy; 0.08 ± 0.01 vs. 0.07 ± 0.01; 1179.26 ± 110.55 vs. 1099.3 ± 80.9). Comparison of organs at risk showed that compared with the 10 MV group, the 6 MV group demonstrated significantly lower V_40Gy of the bladder, D_5% of the right femoral head, and D_2% and V_5Gy of Body-PTV (60.37 ± 13.66 vs. 60.84 ± 13.88; 37.09 ± 5.43 Gy vs. 38.03 ± 5.68 Gy; 41.71 ± 1.39 Gy vs. 42.16 ± 1.31 Gy; 47.88 ± 9.75 vs. 48.23 ± 9.74). There were no significant differences in other parameters between the two groups. Conclusion The VMAT plans with 6 MV and 10 MV X-ray photon energies both meet the clinical needs of cervical cancer radiotherapy. The cervical cancer VMAT plan with 6 MV photon energy is recommended due to better protection of the organs at risk.

Objective To investigate the effects of volumetric modulated arc therapy (VMAT) with 6 MV and 10 MV X-ray photon energies in patients with cervical cancer. Methods From March 2019 to May 2020, 24 patients with cervical cancer who underwent radiation therapy in the Oncology Radiotherapy Department of our hospital were selected. VMAT plans with 6 MV and 10 MV photon energies were re-designed for each patient. The target parameters (D_98%, D_2%, D_mean), conformal index, and homogeneity index of the two groups were compared. The radiation doses received by the bladder, rectum, small intestine, left femoral head, right femoral head, and normal tissue other than planning target volume (Body-PTV), as well as monitor units and estimated total delivery time, were also compared. Results D_2%, D_mean, homogeneity index, and monitor units were significantly lower in the 10 MV group than in the 6 MV group (50.78 ± 0.33 Gy vs. 50.35 ± 0.29 Gy; 49.05 ± 0.2 Gy vs. 48.93 ± 0.17 Gy; 0.08 ± 0.01 vs. 0.07 ± 0.01; 1179.26 ± 110.55 vs. 1099.3 ± 80.9). Comparison of organs at risk showed that compared with the 10 MV group, the 6 MV group demonstrated significantly lower V_40Gy of the bladder, D_5% of the right femoral head, and D_2% and V_5Gy of Body-PTV (60.37 ± 13.66 vs. 60.84 ± 13.88; 37.09 ± 5.43 Gy vs. 38.03 ± 5.68 Gy; 41.71 ± 1.39 Gy vs. 42.16 ± 1.31 Gy; 47.88 ± 9.75 vs. 48.23 ± 9.74). There were no significant differences in other parameters between the two groups. Conclusion The VMAT plans with 6 MV and 10 MV X-ray photon energies both meet the clinical needs of cervical cancer radiotherapy. The cervical cancer VMAT plan with 6 MV photon energy is recommended due to better protection of the organs at risk.

Objective:In this retrospective study, the accuracy and outcomes of segmental Le Fort I surgery with the aid of 3D-printed surgical templates and occlusal splints and dental model surgery were evaluated.Methods:Clinical data of patients receiving segmental Le Fort I surgery in the Department of Orthognathic and Temporo-Mandibular Joint Surgery of West China Stomatological Hospital of Sichuan University from January 2014 to June 2019 were retrospectively analyzed. The accuracy of virtual surgical planning(VSP) and the difference between VSP and dental model surgery were evaluated by postoperative complications, color distance maps, and quantitative accuracy analysis.The amount of surgical displacement of the maxilla in the three-dimensional direction before and after surgery, the occurrence of postoperative complications and the patients'satisfaction survey were analyzed in both groups. Paired t-tests were used for the linear distance and angle between the preoperative design model and the final virtual surgery model in the digital surgery group. Independent samples t-test was used for each marker point’s preoperative and postoperative displacements in the three-dimensional direction between the digital surgery group and the dental model group. The proportion of postoperative complications in the 2 groups was tested using the Pearson chi-square test, and the difference was considered statistically significant at P<0.05. Results:There were 129 patients in the digital surgery group, 35 males and 94 females, aged (24.5±6.5) years, and 92 patients in the dental model surgery group, 28 males and 64 females, aged (27.7±5.4) years.The overall mean linear difference was 1.23±0.35 mm, and the overall mean angular difference was 2.48°±0.31°. The vertical displacement of U3R, U6L in the digital surgery group was (6.72±1.57)mm and (4.73±2.07)mm. The vertical displacement of U3R, U6L in the group of dental model surgery was (4.07±2.14)mm and (1.62±1.82)mm.The significant deviation difference in U3R-Y and U6L-Y between two groups could be detected. The complications in two groups showed a significant difference. Except for one case of root injury, there was no serious complication recorded in the digital surgery group. However, there were three cases of palatal fistulas, four cases of root injury and two cases of bone dehiscence in the dental model group. 94.5% of patients in the digital surgery group are satisfied with the surgical results, while 89.1% in the dental model group.Conclusion:Compared with dental model surgery, segmental Le Fort I surgery is highly accurate under the guidance of surgical templates and occlusal splint which has better postoperative results and effectively reduces the occurrence of surgical complications.

Objective:To evaluate the stability of the zygomatic complex in reduction malarplasty (RM) with different fixation method.Methods:The clinical data of patients with zygomatic arch protrusion at the Department of Orthognathic and Temporomandibular Joint Surgery, West China Hospital of Stomatology, Sichuan University from January 2018 to January 2021 were analyzed retrospectively. All patients underwent L-shaped osteotomy reduction malarplasty which were divided into zygomatic body fixation (ZBF) and zygomatic arch fixation (ZAF) according to fixation technique. As for ZBF, there were 4 different groups including two bicortical screws (2LS), an L-shaped plate with one bicortical screw (LPLS), an L-shaped plate with short-wing on the zygoma (LPwZ) and an L-shaped plate with short-wing on the maxilla (LPwM). As for ZAF, there were 3 different groups including mortice-tenon (MT), 3-hole plate (3HP) and short screw (SS). CT imaging data of two postoperative periods (1 week later; 6 months later) were collected. ITK-SNAP and 3D Slicer software were applied to evaluate the difference in the displacement distance of relevant landmarks of the zygomatic complex, so as to compare the postoperative stability of RM under different fixation methods. Statistical analyses were performed using IBM SPSS Statistics, version 25.0, and Kruskal-Wallis method was used to compare the difference of relevant landmarks displacement distance between ZBF group and ZAF group. P<0.05 was considered statistically significant. Results:60 patients (120 zygomatic arches) who were composed of 21 men and 39 women, aged (27.1±4.9) years were included. There were 30 samples in each group of ZBF and 40 samples in each group of ZAF. Compared with the single L-shaped plate (LPwZ, LPwM) group, the displacement distance of zygomatic complex in 2LS and LPLS groups was shorter ( P<0.05). The three fixation method of zygomatic arch (MT, 3HP, SS) had similar effects on the displacement of zygomatic complex ( P>0.05). Conclusion:After RM, the "two-bridge" fixation method (2LS and LPLS) provides better stability than the single L-shaped plate. The stability of all ZAF is similar when combined with 2LS or LPLS.

Objective:In this retrospective study, the accuracy and outcomes of segmental Le Fort I surgery with the aid of 3D-printed surgical templates and occlusal splints and dental model surgery were evaluated.Methods:Clinical data of patients receiving segmental Le Fort I surgery in the Department of Orthognathic and Temporo-Mandibular Joint Surgery of West China Stomatological Hospital of Sichuan University from January 2014 to June 2019 were retrospectively analyzed. The accuracy of virtual surgical planning(VSP) and the difference between VSP and dental model surgery were evaluated by postoperative complications, color distance maps, and quantitative accuracy analysis.The amount of surgical displacement of the maxilla in the three-dimensional direction before and after surgery, the occurrence of postoperative complications and the patients'satisfaction survey were analyzed in both groups. Paired t-tests were used for the linear distance and angle between the preoperative design model and the final virtual surgery model in the digital surgery group. Independent samples t-test was used for each marker point’s preoperative and postoperative displacements in the three-dimensional direction between the digital surgery group and the dental model group. The proportion of postoperative complications in the 2 groups was tested using the Pearson chi-square test, and the difference was considered statistically significant at P<0.05. Results:There were 129 patients in the digital surgery group, 35 males and 94 females, aged (24.5±6.5) years, and 92 patients in the dental model surgery group, 28 males and 64 females, aged (27.7±5.4) years.The overall mean linear difference was 1.23±0.35 mm, and the overall mean angular difference was 2.48°±0.31°. The vertical displacement of U3R, U6L in the digital surgery group was (6.72±1.57)mm and (4.73±2.07)mm. The vertical displacement of U3R, U6L in the group of dental model surgery was (4.07±2.14)mm and (1.62±1.82)mm.The significant deviation difference in U3R-Y and U6L-Y between two groups could be detected. The complications in two groups showed a significant difference. Except for one case of root injury, there was no serious complication recorded in the digital surgery group. However, there were three cases of palatal fistulas, four cases of root injury and two cases of bone dehiscence in the dental model group. 94.5% of patients in the digital surgery group are satisfied with the surgical results, while 89.1% in the dental model group.Conclusion:Compared with dental model surgery, segmental Le Fort I surgery is highly accurate under the guidance of surgical templates and occlusal splint which has better postoperative results and effectively reduces the occurrence of surgical complications.

Objective:To evaluate the stability of the zygomatic complex in reduction malarplasty (RM) with different fixation method.Methods:The clinical data of patients with zygomatic arch protrusion at the Department of Orthognathic and Temporomandibular Joint Surgery, West China Hospital of Stomatology, Sichuan University from January 2018 to January 2021 were analyzed retrospectively. All patients underwent L-shaped osteotomy reduction malarplasty which were divided into zygomatic body fixation (ZBF) and zygomatic arch fixation (ZAF) according to fixation technique. As for ZBF, there were 4 different groups including two bicortical screws (2LS), an L-shaped plate with one bicortical screw (LPLS), an L-shaped plate with short-wing on the zygoma (LPwZ) and an L-shaped plate with short-wing on the maxilla (LPwM). As for ZAF, there were 3 different groups including mortice-tenon (MT), 3-hole plate (3HP) and short screw (SS). CT imaging data of two postoperative periods (1 week later; 6 months later) were collected. ITK-SNAP and 3D Slicer software were applied to evaluate the difference in the displacement distance of relevant landmarks of the zygomatic complex, so as to compare the postoperative stability of RM under different fixation methods. Statistical analyses were performed using IBM SPSS Statistics, version 25.0, and Kruskal-Wallis method was used to compare the difference of relevant landmarks displacement distance between ZBF group and ZAF group. P<0.05 was considered statistically significant. Results:60 patients (120 zygomatic arches) who were composed of 21 men and 39 women, aged (27.1±4.9) years were included. There were 30 samples in each group of ZBF and 40 samples in each group of ZAF. Compared with the single L-shaped plate (LPwZ, LPwM) group, the displacement distance of zygomatic complex in 2LS and LPLS groups was shorter ( P<0.05). The three fixation method of zygomatic arch (MT, 3HP, SS) had similar effects on the displacement of zygomatic complex ( P>0.05). Conclusion:After RM, the "two-bridge" fixation method (2LS and LPLS) provides better stability than the single L-shaped plate. The stability of all ZAF is similar when combined with 2LS or LPLS.

Objective:To investigate the effects of breast milk to total milk intake ratio during hospitalization on the duration of antibiotic therapy in preterm infants less than 34 weeks of gestation.Methods:Clinical data of preterm infants ( n=1 792) less than 34 gestational weeks were retrospectively collected in 16 hospitals of Jiangsu Province Neonatal-Perinatal Cooperation Network from January 1, 2019, to December 31, 2021. The days of therapy (DOT) were used to evaluate the duration of antibiotic administration. The median DOT was 15.0 d (7.0-27.0 d). The patients were divided into four groups based on the quartiles of DOT: Q 1 (DOT≤7.0 d), Q 2 (7.0 d27.0 d) groups. According to the breast milk intake ratio (breast milk intake to total milk intake during hospitalization×100%), they were also divided into four groups: very-low-ratio breastfeeding group (breast milk intake ratio≤25%), low-ratio breastfeeding group (25%75%). Univariate analysis ( Chi-square test and Kruskal-Wallis rank-sum test) was used to analyze the factors influencing DOT. Spearman correlation analysis and trend Chi-square test were used to explore the relationship between breast milk intake ratio and DOT. After using multiple imputations to address missing data, two models were constructed after adjusting for different factors, and multinomial logistic regression model was applied to evaluate the effects of the breast milk intake ratio on DOT. Finally, sensitivity analysis was conducted to assess the stability of the models. Results:(1) Of the 1 792 preterm infants, there were 507 (28.3%) in the Q 1 group, 422 (23.5%) in the Q 2 group, 438 (24.4%) in the Q 3 group and 425 (23.7%) in the Q 4 group. (2) The median values of DOT in the very-low-ratio, low-ratio, medium-ratio and high-ratio breastfeeding groups were 20.0 d (11.0-31.0 d), 20.0 d (11.0-32.0 d), 13.0 d (6.0-25.8 d) and 10.0 d (4.0-21.0 d), respectively. Compared with the very-low-ratio and low-ratio breastfeeding groups, the medium-ratio and high-ratio breastfeeding groups had shorter DOT (all P<0.05). (3) After adjusting for factors with P<0.1 (prenatal glucocorticoid exposure, antimicrobial use within 24 h before delivery, gestational age at delivery, birth weight, Apgar score≤7 at 1 min, neonatal respiratory distress syndrome, infectious pneumonia and early-onset neonatal sepsis) between the DOT quartile groups, it showed that medium-ratio and high-ratio breastfeeding were protective factors in contrast to very-low-ratio breastfeeding in the Q 2, Q 3 and Q 4 groups as compared with the Q 1 group [Q 2 group: OR=0.50 (95% CI: 0.30-0.85) and OR=0.36 (95% CI: 0.26-0.51); Q 3 group: OR=0.31 (95% CI: 0.18-0.55) and OR=0.20 (95% CI: 0.14-0.29); Q 4 group: OR=0.22 (95% CI: 0.12-0.42) and OR=0.17 (95% CI: 0.12-0.26)]. Conclusion:Breast milk intake accounting for over 50% of total milk intake has a positive impact on reducing DOT in premature infants requiring antibiotics, which suggests that breastfeeding should be actively encouraged.

Objective:To investigate the daily diet and living habits of Hashimoto's thyroiditis (HT) patients, and to explore the influencing factors of HT.Methods:The patients admitted to the Thyroid Surgery Clinic of Cancer Hospital Affiliated to Harbin Medical University from March to December 2021 were selected as the investigation subjects and were divided into observation group (106 patients with HT) and control group (63 healthy people). Questionnaire was used to collect the information of daily diet and living habits of the two groups, and physical examination was used to collect the information of height and weight. The levels of serum thyroid function indicators thyroid stimulating hormone (TSH), free triiodothyronine (FT 3) and free thyroxin (FT 4) were tested by automatic chemiluminescence immunoassay, and the comparison and analysis were conducted between the two groups. Multivariate logistic regression was used to analyze the influencing factors of HT. Results:The results of univariate analysis showed that there were significant differences in sex ratio and serum TSH levels between the two groups ( P < 0.05); the proportion of people in observation group who slept for less than 6 hours per day, frequently looked at their mobile phones, ate fried food ≥1 time per week, and ate meat ≥1 kg per week was higher than that in control group; however, the proportion of people in observation group who drank tea ≥1 time per week, smoked ≥1 time per week, had a salty daily taste, ate nuts ≥1 time per week, and ate vegetables ≥1 kg per week was lower than that in control group, and the differences were statistically significant ( P < 0.05). The results of multivariate logistic regression analysis showed that female, slept duration < 6 hours/day, weekly meat consumption ≥1 kg, and elevated serum TSH levels were risk factors for the onset of HT [odds ratios ( OR) = 3.37, 4.11, 2.48, 1.14, and 95% confidence intervals ( CI): 1.08 - 10.55, 1.46 - 11.59, 1.00 - 6.51, 1.00 - 1.30]; eating ≥1 kg of vegetables per week was a protective factor for the onset of HT ( OR = 0.36, 95% CI: 0.17 - 0.79). Conclusion:Female, poor diet and lifestyle habits are risk factors for the onset of HT.

Objective To investigate the dosimetric differences between volumetric modulated arc therapy (VMAT) with a flattening filter (FF) and flattening filter-free (FFF) VMAT in fractionated stereotactic radiotherapy for brain metastases. Methods Seventeen patients with brain metastases were divided into FF-VMAT group (VMAT plans with the FF mode) and FFF-VMAT group (VMAT plans with the FFF mode). The two groups were compared in terms of target volume dose parameters (D_98%, D_2% and D_mean), the conformal index (CI), the gradient index (GI), the gradient, normal brain tissue dose parameters (V_5Gy, V_10Gy, V_12Gy and D_mean), monitor units, and beam-on time. Results Compared with the FF-VMAT group, the FFF-VMAT group had significantly lower GI (3.33 ± 0.37 vs 3.27 ± 0.35, P = 0.001), a significantly lower gradient [(0.85 ± 0.20) cm vs (0.84 ± 0.19) cm, P = 0.002], a significantly shorter beam-on time [(177.05 ± 62.68) s vs (142.71 ± 34.59) s, P = 0.001], and significantly higher D_2% [(65.69 ± 2.15) Gy vs (66.99 ± 2.03) Gy, P = 0.001] and D_mean [(58.77 ± 1.60) Gy vs (59.95 ± 1.43) Gy, P <0.001]. There were no significant differences in the CI, the D_98% of the target volume, the V_5Gy, V_10Gy, V_12Gy and D_mean of the normal brain tissue, and monitor units between FFF-VMAT and FF-VMAT. Conclusion FFF-VMAT can better protect the normal tissue around the target volume, reduce the beam-on time, and improve treatment efficiency.

Objective To investigate the dose calculation accuracy of two algorithms in Monaco TPS for self-made phantoms with different cavity thickness, and analyze the influence of phantoms with different cavity thickness on dose verification of upper esophageal cancer. Methods The phantoms with different cavity thickness were placed on the simulated CT positioning machine to scan and acquire images. In Monaco TPS, the irradiation fields with energy of 6 MV, 100 MU and different square field sizes were added to the acquired images. The dose of the cavity of the ionization chamber was calculated by two algorithms, and measured on the accelerator by dosimeter under the same conditions. At the same time, 20 patients with upper esophageal cancer who received dynamic intensity modulation in fixed field were randomly selected and included in the study, and two algorithms were used for dose verification on phantoms with different cavity thickness. The results were statistically analyzed by SPSS 22.0 software. Results The maximum deviations between the calculated values and the measured values were 0.66% and −1.8%, in the calculation of phantoms with different cavity thickness by algorithms of Monte Carlo and Pencil Beam. In Monte Carlo algorithm, the result of RD pair t test is P > 0.05. Paired t test of AD (0 mm, 10 mm), (5 mm, 10 mm) and (10 mm, 20 mm) groups showed no significant difference (P < 0.05). The maximum deviation was 1.1%, and the rest groups were not statisticely significant (P > 0.05); In Pencil Beam algorithm the t test results of RD (0 mm, 20 mm) and (5 mm, 20 mm) pairs were (P < 0.05), the maximum deviation was 0.58%, and the rest groups were (P > 0.05). In AD group, (P < 0.05), the maximum deviation was 2.78%; The paired t test between the two algorithms was (P < 0.05), and the maximum deviations in RD and AD groups were 2.49% and 4.14%, respectively. Conclusion Monte Carlo algorithm has accurate calculation and high gamma pass rate of dose verification, and there is no clinical difference in gamma pass rate of dose verification among phantoms with different cavity thickness, pencil Beam algorithm is not recommended in cavity phantom calculation.