Objective To compare the dosimetric effects of systematic MLC leaf position errors on flattening filter (FF) and flattening filter-free (FFF) IMRT for nasopharyngeal carcinoma (NPC).Methods In totaly of ten patients with NPC were enrolled in the current study.FF IMRT and FFF IMRT plans were designed for each patient, and in-house software was developed to modify the corresponding MLC files.Briefly, three kinds of systematic MLC error presented with 0.5 and 1 mm magnitudes error were simulated.The modified MLC files were re-imported into IMRT plans for dose recalculation, and differences in the dosimetry trends between FF-IMRT and FFF-IMRT plans were analyzed using a dosevolume histogram.Results Upon closed MLC, the average changes in D95％ of PTV and D of parotid glands in FFF-IMRT plans were more sensitive than in FF-IMRT plans (t =3.298-4.793, P ＜ 0.05).Otherwise, when MLC are shifted in the same direction, changes in D95％of PTV, D of PGTV, PTV as well as D of left parotid gland in FFF-IMRT plans were also more sensitive (t =2.372-6.844, P ＜ 0.05), whereas average changes in D of right parotid gland presented with less sensitivity (t =-4.049,-3.378, P ＜ 0.05).Conclusions For out-of-field or large organs, FFF-IMRT plans are more sensitive to leaf position error than FF-IMRT plans.

Objective To explore the dosimetric difference between different radiotherapy technologies in the treatment of early peripheral stage non?small ?cell lung cancer ( NSCLC ) . Methods Four?dimensional computed tomography scans and delineation of target volumes and organs at risk ( OARs) were performed in 5 patients pathologically diagnosed with stage T1/T2 peripheral NSCLC who were admitted from 2014 to 2015. Target volumes contained gross tumor volume (GTV), internal target volume (ITV), and planning target volume (PTV). ITV was contoured on the maximum intensity projection images. PTV was defined as ITV plus a 5 mm margin. OARs contained the heart, lung, esophagus, and spinal cord. The Monaco 5. 0 treatment planning system was used to design three plans. The three?dimensional conformal radiotherapy (3DCRT) plan had 11 fields in the diseased lung covering the PTV plus a 0. 2 cm margin. The sliding window intensity?modulated radiotherapy ( SW?IMRT ) plan had 9 fields in the same areas as the 3DCRT plan. The volumetric modulated arc therapy ( VMAT) plan had the gantry rotating 180° around the diseased lung. The evaluation criteria referred to the RTOG 0618 trial. Comparison was made by paired t test. Results The SW?IMRT plan had a significantly better homogeneity index than the 3DCRT plan ( 1. 03 vs. 1. 24,P= 0. 017 ) . Compared with the VMAT plan, the mean monitor units in the 3DCRT plan was significantly reduced by 24. 5%( P=0. 022) . The V30 and V40 of the 3DCRT plan were significantly reduced by 29. 4% and 28. 4%, respectively, compared with the SW?IMRT plan ( P=0. 003,0. 006) and 56. 7%and 59. 7%, respectively, compared with the VMAT plan ( P=0. 041,0. 019) . Conclusions 3DCRT may be an appropriate radiotherapy method for early stage NSCLC.

Objective To evaluate effects of glucocorticoids on maxillary bone mineral density in rats with acute adriamycin-induced nephrotoxicity (ADR). Methods Forty rats were randomly divided into four groups, control group, glucocorticoids- treated group, ADR group and ADR + glucocorticoids- treated group. ADR group and ADR +glucocorticoids-treated group were given 4 mg/kg adriamycin injection via tail vein to establish ADR model. Control group and glucocorticoids-treated group were given 4 mg/kg saline injection via tail vein. After establishment of ADR model, glucocorticoids-treated group and ADR + glucocorticoids-treated group were intragastric administration of 30 mg/(kg · d) methylprednisolone for 10 weeks, and control group and ADR group were given the same volumes of normal saline. Values of bone calcium pigment (BGP), type Ⅰ collagen, N-terminal pro-peptide (PINP), β-Ⅰ type collagen C-terminal cross-linked telopeptide (CTX) were detected by ELISA. The micro-CT scan was used to measure Tb.Th, Tb.Sp, Tb.N, BVF and bone mineral density (BMD). Results Compared with other three groups, the levels of BGP and PINP were significantly decreased, and CTX were significantly increased in ADR + glucocorticoids-treated group (P<0.05). Micro-CT analysis showed that there was significant maxillae osteoporosis, including changes of porous micro architecture, lower BMD, decreased BVF, lower Tb.Th and widening Tb.Sp in ADR + glucocorticoids-treated group (P<0.05). There was no significant difference in Tb.N between four groups. Conclusion There is imbalanced bone metabolism in rat model of ADR. High-dose hormone therapy can accelerate the occurrence of osteoporosis, decrease bone metabolism, and affect bone structure.

Objective To investigate the local or systemic effects of initial periodontal therapy on peritoneal dialysis in patients with chronic kidney disease and periodontitis. Methods Sixty-one patients with both periodontitis and regular peritoneal dialysis were selected in this study and were randomly divided into observation group (n=31) and control group (n=30). Patients in observation group were given periodontal initial therapy (ultrasonic supragingival scaling and ultrasonic subgingival irrigation, drug, root planing, oral health education) and peritoneal dialysis treatment. Patients in control group were given only peritoneal dialysis treatment. Clinical parameters including plaque index (PLI), gingival index (GI) and probing depth (PD) were detected before and one month after treatment in two groups. The concentrations of high-sensitivity C-reactive protein (hs-CRP) in gingival sulcus fluid and serum samples were measured by immune transmission turbidity method in two groups. Results There were no significant differences in PLI, GI, PD, hs-CRP of gingival sulcus fluid, and serum hs-CRP before treatment between the two groups. After one-month initial therapy, all the indexes were decreased in observation group, which were significantly different compared with those before treatment (P<0.05). And all the indexes were significantly lower in observation group than those of control group. There were no significant differences in PLI, PD, GI, hs-CRP of gingival sulcus fluid, and serum hs-CRP between control group and observation group before treatment. Conclusion Periodontal initial treatment can improve the periodontal inflammation in patients with chronic kidney disease, and reduce the concentration of systemic inflammatory factor hs-CRP, decreasing the risk of infection.

BACKGROUND:Artificial femoral head replacement provides a new idea for the repair of unstable intertrochanteric fracture. Artificial prosthesis replacement may affect original femoral biomechanical stability and lead to a variety of adverse consequences. OBJECTIVE:To analyze the stress distribution of femoral head replacement in the treatment of unstable femoral intertrochanteric fractures with three-dimensional finite element analysis. METHODS:One male old volunteer was randomly selected from population who underwent health examination. The left femur was scanned with spiral CT, and the three-dimensional finite element models of the human femur and prosthesis were established. The three-dimensional finite element model was used to simulate the actual working conditions of human climbing stairs, and the stress distribution of the bone channels around the surface of the femur and the prosthesis was analyzed with three-dimensional finite element analysis. RESULTS AND CONCLUSION: Under normal condition, the stress of the human femur was in a consistent state. Stress changed gradualy from the proximal end to the distal end. The stress of the prosthesis was concentrated in the middle section. The prosthesis of inner stress distribution was analyzed to obtain stress distribution of prosthesis and femur cancelous bone interface. The analysis found that stress change trend was consistent. The results suggest that artificial femoral head replacement does not have a significant effect on the overal stress distribution of the human femur, and the overal stress distribution does not change, and the maximum stress region is located in the middle of the whole femur. After the reconstruction, the stress concentration of the femur is not observed.

Objective To analyze the clinical application of donor specific antibodies (DSAs) detected by a single antigen Luminex virtual crossmatch,and to discuss the treatment of DSA and the impact of DSA on renal function.Methods Serum from living-relative renal recipients before and after transplantation was investigated using a Luminex single antigen assay.The relation between DSA and renal acute rejection as well as renal function was analyzed.Results A total of 30 patients and 173 serum samples were tested,including 47 serum samples before transplantation,and 126 after transplantation.DSA was positive in one patient before transplantation,and 8 patients after transplantation.Three of the patients positive for DSA were treated by Bortezomib,3 by addition of MMF,2 by addition of CNI,1 by addition of Sirolimus.The MFI of DSA in one of the patients treated by Bortezomib was decreased to below 1000,while that in the other two decreased by more than 50 ％.The renal eGFR at the time with and without DSA was (1.50 ± 0.59) and (1.23 ± 0.38)ml/s respectively (P＜0.05).Conclusion Dynamic monitoring of single bead antigen antibody DSA conduces to direct the adjustment of immunosuppressant.The appearance of DSA contributes to the declination of renal function.Application of Bortezomib decreased the MFI of DSA.

Objective:To study the changing characteristics and impact factors of helical tomotherapy (HT)for longitudinal dose fall-off outside the target, in order to guide the plan junction or pretreatment target and implementation efficiency in clinical.Methods:Eight patients with head and neck tumors admitted to the Department of Oncology Radiotherapy of the First Affiliated Hospital of Zhengzhou University in December 2019 were retrospectively selected as the research objects. The planning target area and dose drop structure were outlined in the head and neck images with a thickness of 1 mm obtained by Siemens SOMATOM Definition AS positioning computerized tomography (CT). Different field widths (FW, 5.0 cm/2.5 cm/1.0 cm) and pitches (0.430/0.287/0.215) were assembled for planning with the same modulation factor (1.8), finest does calculation grid (0.195 cm ×0.195 cm) and other planning parameters were consistent. The plans were designed by different parameters, and the result was analyzed by univariate analysis.Results:The that different pitch curves coincided under the same field width by comparative analyzing, so pitchs had no effect on dose drop. The different field width curves were independent of each other, indicating that the field width had an effect on dose drop in the head and foot direction. The relationship between the longitudinal dose drop speed outside the target and the change of the field width was inversely correlated: the larger field widths meant the slower dose fall-off and the larger penumbra, while the smaller field widths meant the faster fall-off and the smaller penumbra. When the dose fall-off to 50% of the prescribed dose, the distance from the target was approximately equal to half the field widths, and the pitchs had not affect the rate of dose-drop, while the dose at different distances from the target boundary could be calculated by the fitting formulas. The field widths and pitchs had little effect on the CI and HI index of the target, relatively, the target area was best when the field width was 2.5 cm. The total beam-on time gradually decreased with the increase of the field widths and pitches.Conclusions:When segment target therapy needs to consider planning junction, execution efficiency, and controlling longitudinal dose fall-off and considered the execution, the optimal planned parameters such as field widths and pitches could be selected or the target at the junction regions could be adducted according to the longitudinal dose drop formula, so as to achieve the ideal dose distribution.

Objective: To achieve quantitative analysis of image quality parameters and establish warning and action thresholds for the on-board imaging (OBI) system of linear accelerator. Methods: The Catphan604 phantom was repeatedly scanned in the Full-Fan and Half-Fan CBCT scanning modes on a Varian EDGE linear accelerator, and the software based on Python language development in-house was utilized to analyze image quality parameters, such as CT number linearity, geometric consistency, slice thickness, spatial resolution, uniformity and low-contrast resolution. The quantitative analysis results of each image quality parameter obtained from 16 times of scanning within 16 months were normalized to the mean and the standard deviations were recorded. A run chart analysis was created to determine the warnings and action thresholds. Results: The software built in-house can quantitatively analyze the image parameters of the two scanning modes of OBI system. The low-contrast resolution of Half-Fan was better than that of Full-Fan, whereas the spatial resolution of Full-Fan was superior to that of Half-Fan. One standard deviation (1σ) was set as the warning threshold and 2 standard deviations (2σ) as the action threshold, respectively. The tolerance level of Half-Fan was smaller than that of Full-Fan. Conclusion Self-developed software enables quantitative analysis of accelerator image quality parameters, establishes warning and action tolerance of quality assurance and provides guidance for image quality assurance under image-guided radiotherapy specification.

Objective To investigate the optimal distance between the upper and lower targets in the subsection total body irradiation(TBI)using helical tomotherapy,and to analyze the dose distribution of abutment regions. Methods A total of 8 patients with acute leukemia with a height of about 120 cm were involved in the study. All patients were scanned from the calvarium to the toe by computerized tomography (CT,Siemens)with a thickness of 5 mm,and a lead wire was placed at a point 10 cm above the patella as a marker of the boundary between the upper and lower targets. The delineation of target volumes and organs at risk(OAR)was performed in the Varian Eclipse 10.0 doctor workstation. The different distances between the lead wires and the boundary of the two targets were delineated, and images were transferred to the HT workstation to design the radiotherapy planning,including Jaw width(5 cm),modulation factor(1.8),and pitch(0.43). The plans were superimposed together, and then the dose distribution in abutment regions with different target gaps was analyzed to find the optimal distance. Results When the target gap was 5 cm, the dose distribution in abutment regions was satisfactory. However,the dose was obviously insufficient when the gap was more than 5 cm;the doses in abutment regions significantly exceeded the prescribed doses when the gap was less than 5 cm. Conclusions In the subsection TBI using HT, different parameters were designed,including Jaw width(5 cm), modulation factor(1.8), pitch(0.43), and slice thickness(5 mm). The upper and lower borders of the targets should be 2.5 cm away from the lead wire,that is,a gap of 5 cm,thus avoiding the dose-related hot or cold spots in the target convergence and ensuring a safer and more accurate radiotherapy.

Objective Based on lung cancer center database,we analyzed the clinical characteristics of lung patients with bone metastases.The relationship between bone metastases,skeletal-related events,survival time and different pathological subtypes of lung cancer were also evaluated in this study.Methods A total of 861 patients with lung cancer were studied from May 2010 to April 2012 at Tianjin Medical University Cancer Institute and Hospital.As to follow-up situation,patients' survival status and treatment information were collected by telephone follow-up and (or) examinationsin outpatient.The clinical characteristics,skeletal-related events and survival of bone metastaticpatients with different pathological types of lung cancer were analyzed.Logistic regression analysis was used to identify risk factors for bone metastases.The relationship between histological subtypes and the incidence of bone metastases was evaluated using Odds Ratios (ORs).The chi-square test was used to compare the proportion of bone metastases,synchronous bone metastases and SREs among different histological subtypes patients.The overall survivals was evaluated using the Kaplan Meier.Results A total of 861 patients with lung cancerwere enrolled in this study,including 293 cases with bone metastases.The average follow-up of our population was 14.2 months and the last follow-up time was September 2017.Among different pathological types of lung cancer,adenocarcinoma (39.14％,173/442) has the highest incidence of bone metastases,followed by other types (29.91％,35/117),squamous cell carcinoma (29.47％,56/190) and SCLC (25.89％,29/112).Spine (59.73％,175/293) was the most common location site of the bone metastases,followed by the ribs (49.15％,144/293),pelvis (20.48％,60/293),femur (16.38％,48/293) and sternal (16.38％,48/293).Lung adenocarcinoma was a risk factor for bonemetastases (P=0.002).In ORs analyze,adenocarcinoma patients were more likely to develop bone metastases [OR=1.60,95％CI (1.21～2.13)].In our cohort,58.36％of patients with lung cancer had skeletal related events.Among various types of skeletal related events of patients with bone metastases,the most common one was radiotherapy for bone metastases (51.88％,152/293),followed by pathological fractures (15.02％,44/293),spinal cord compression (6.48％,19/293),bone instability requiring surgery (4.78％,14/293) and hypercalcemia (1.71％,5/293).There was no significant difference between different types of skeletal related events.The median survival time of the patients with bone metastases was 11.5 months.There was no significant difference in survival between adenocarcinoma patients and non-adenocarcinoma patients (P=0.111).Conclusion This study suggested that the incidence of bone metastasis in lung adenocarcinoma was 39.14％ and lung adenocarcinoma was a risk factor for bone metastases,which supported early screening and monitoring of bone metastasis in the patients.