Objective:To evaluate the dosimetric characteristics, safety and effectiveness of magnetic resonance-guided fractionated stereotactic radiotherapy (FSRT) for brain tumors.Methods:Clinical data of 8 brain tumor patients treated with magnetic resonance-guided FSRT in the Radiotherapy Department of the First Medical Center of the PLA General Hospital from July 2023 to February 2024 were retrospectively analyzed. Online adaptive radiotherapy was adopted for all patients. Adapt-to-position (ATP) or adapt-to-shape (ATS) radiotherapy was chosen by radiologists. Each adaptation was initiated after the radiotherapy plan was re-examined. The radiotherapy fractionation plan was 21-30 Gy/3-5 F. Clinical characteristics, radiotherapy plans and plan parameters were analyzed by statistical description. Median ( Q1， Q3) was used to describe continuous data and percentage was used to describe categorical data. Results:In this study, 9 lesions were treated a total of 41 times, including 20 times (49%) of ATP plan and 21 times (51%) of ATS plan. The median target area coverage rate was 95.1% (95%, 99.8%), the median target area maximum dose rate was 1.15 (1.07, 1.31), the median conformity index (CI) was 0.75 (0.69, 0.86), the median homogeneity index (HI) was 1.09 (1.06, 1.21), and the median gradient index (GI) was 4.73 (3.36, 8.45), respectively. After ATS plan, the median reduction in gross target volume (GTV) was 8.22 cm3 (1.2, 10.1 cm3), and the median reduction in brain tissue V12 Gy was 30.46 cm3 (8.34, 31.13 cm3).The median follow-up was 3.2 months (1.4, 6.1 months). No radiation necrosis was found in any patient. There were 2 cases of acute brain edema during radiotherapy (both were mild). Except for 1 case who died due to systemic disease progression, the remaining patients had no local recurrence, and achieved good quality of life. Conclusions:The parameters of the treatment plan of magnetic resonance-guided FSRT are generally acceptable. The adaptive plan can effectively reduce the dose of normal brain tissues. It is safe and feasible to use the magnetic resonance-guided FSRT for brain tumors.

Objective:To investigate the regulatory role of mesenchymal stem cells(MSCs)on radiation-induced lung injury in mice by the ferroptosis pathway.Methods:The mice were divided into normal control group,MSCs-treated group(MSCs group),single irradiation group(IR group)and IR combined with MSCs group(IR+MSCs group)according to random number table method before irradiation.A mouse model of radiation-induced lung injury was constructed using whole thorax irradiation with cobalt 60(60Co)(20Gy each time),and TNF-α and IL-6 levels of mouse were detected by enzyme-linked immunosorbent assay(ELISA).The injury of lung tissue in mice was assessed using hematoxylin eosin(HE)staining and Masson staining.Western Blot was used to examine the expression levels of ferroptosis-related proteins in lung tissue,including nuclear factor erythroid NF-E2 related factor 2(Nrf2),4-Hydroxynonenal(4-HNE)and glutathione peroxidase 4(GPX4).The expression level of prostaglandin-endoperoxide synthase 2 Gene(PTGS2)in the lung tissue of mice was detected by using quantitative polymerase chain reaction(qPCR),and the level of reactive oxygen species(ROS)in the lung tissue of mice was detected after radiation by using dihydroethidium(DHE),and the level of malondialdehyde(MDA)content in the lung tissue was detected after radiation.And then,the level of oxidative damage in the lung tissue of mice was assessed.Results:Elisa results showed the serum TNF-α and IL-6 levels in mice after irradiation in IR group were significantly higher than those in normal control group(F=53.60,10.65,P＜0.05),respectively.The HE and MSCs staining of pathological analysis showed that MSCs treatment could significantly relieve both early radiation-induced pneumonitis and advanced pulmonary fibrosis.After radiation,the 4-HNE expression level was upregulation and the Nrf2 expression level was downregulation in the lung tissues of mice,whereas MSCs were able to significantly reduce the 4-HNE expression and upregulate the Nrf2 expression.The mRNA expression level and MDA content of the ferroptosis gene PTGS2 were significantly increased,which were significantly higher than those of normal control group,while MSCs were able to significantly reduce its expression,and the differences were statistically significant(F=105.8,7.693,P＜0.05).Conclusion:MSCs is able to relieve significantly ionizing radiation-induced ferroptosis of lung epithelial cells,thereby relieve radiation-induced lung injury.

Objective:To compare and study the improvement of different iterative reconstruction(IR)algorithms of the tomotherapy(TOMO)Radixact system on the image quality of megavoltage computed tomography(MVCT)imaging system,and the influence of that on the precision of automatic registration,and to explore the reconstruction algorithm that is suitable for clinical application.Methods:Using the MVCT imaging system to respectively scan the Tomo-Phantom HE phantom and the Catphan 604 phantom,and to analyze three groups of images were generated by three kinds of reconstruction algorithms,which included the Standard(STD)algorithm,IR General(IR-G)algorithm and IR Soft Tissue(IR-ST)algorithm,in MVCT image.The noise index(NI),uniformity index(UI)of image,modulation transfer function(MTF),low contrast visibility(LCV)index and contrast-to-noise ratio(CNR)of three groups of images were calculated respectively.The Lucy phantom was used to test the accuracy of automatic registration algorithm.The registration data of four dimensions,included left-right(X-axis),head-foot(Y-axis),vertical(Z-axis)and free rotation(Roll)around the Y-axis,were used to conduct verification analysis for the influences of them on the precision of automatic registration.Results:The NI values of IR-G and IR-ST reconstruction algorithms were respectively 39.58±0.10 and 14.62±0.26,which were better than 39.58±0.10 of STD algorithm,and the UI values of them were respectively 19.87±0.83 and 15.84±2.51,which were better than 24.51±1.81 of STD algorithm,and LCV values of them were respectively 2.50±0.03 and 1.74±0.11,which were better than 3.67±0.04 of STD algorithm.All of them appeared significant increase,but the resolution with high contrast of MTF were respectively 0.23 and 0.21,which were lower than 0.32 of STD.The overall image quality of the IR algorithms was superior to that of the STD algorithm.In the accuracy test of the automatic registration algorithm,the registration precisions of IR-G and IR-ST algorithms on Y-axis were respectively(0.360±0.142)mm and(0.245±0.050)mm,which were significantly higher than 0.145±0.136 of STD algorithm,and the differences of them were significant(Z=6.0,15.0,P<0.05).The differences of registration precisions of other directions were not significant(P>0.05).Conclusion:The IR algorithm has advantages in terms of noise,uniformity and resolution with low-contrast,however,it shows reduction on resolution with high-contrast.This reduction of resolution with high-contrast do not lead to the decrease of the precision of automatic registration.

Objective:A dose verification system of two-dimensional semiconductor matrix(SRS MapCHECK)was used to verify the dose of the clinical treatment plan of patients who underwent CyberKnife(CK),which realized rapid verification for individualization of radiotherapy plans of patients through analyzed the γ-passing rates of them.Methods:A total of 253 patients with tumor who received CK clinical treatment in the First Medical Center of Chinese PLA General Hospital from March 2021 to May 2023 were selected.Among of them,121 cases received CK treatment on head,and 30 cases received that on lung,and 102 cases received CK treatment on abdomen and other metastatic tumor.In the MultiPlan treatment plan system,the plan of patient was mapped to the integrated model composed of StereoPHAN model and SRS MapCHECK matrix dose verification system by the means of the plan image center overlap.The dose verification was conducted on the plan of each patient on the basis of ensuring the consistency of the number of beam,direction of beam and the monitor unit.The different γ analysis standards(1%/1 mm,2%/1 mm,3%/1 mm,1%/2 mm,2%/2 mm,3%/2 mm,1%/3 mm,2%/3 mm and 3%/3 mm)were adopted to conduct global analysis of absolute dose for each verification plan,and the threshold(TH)of low dose was set as 10%.Results:The γ passing rates of phantom verification plans of 253 patients were respectively(88.64±5.91)%,(95.43±3.40)%,(97.90±2.06)%,(96.51±2.35)%,(98.15±1.68)%,(99.06±1.12)%,(98.30±1.39)%,(99.09±0.97)%and(99.52±0.63)%under different analysis standards.The γ passing rates of other standards of patients with tumor on different parts were larger than 95%except the analysis result of 1%1 mm standard.The overall analysis result of the deviation of central point dose was(-1.30±2.17)%,among of which the tumor of head,abdominal tumors and other metastatic tumor were about approximately-2%,while that of lung tumors were approximately-3%.The deviation of abdominal and other metastatic tumor was the minimum.The correlation analysis showed that the target volume and the size of the minimum collimator were respectively correlated to the dose deviation of the center.Conclusion:SRS MapCHECK dose verification system can conveniently and quickly realize the individualized verification for the plan of patients who receive CK treatment.

Objective:To quantitatively analyze the differences in image quality and generated synthetic-computed tomography(sCT)between cone beam CT(CBCT)and iteration CBCT(iCBCT),which based on filtered back projection(FBP)and iterative reconstruction(IR)techniques of Varian Ethos adaption system.Methods:Using the special Catphan604 phantom of the test of CT image quality,five times of scanning series of CBCT and iCBCT were respectively performed based on thoracic and abdominal scanning protocols,so as to obtain four sets of images,and each set of image included the CBCT image,the composited sCT and iCBCT images based on CBCT,the composited sCT bases on iCBCT.The noise power spectrum(NPS),image uniformity(UI),modulation transfer function(MTF),low-contrast visibility(LCV)and contrast-to-noise ratio(CNR)of them were analyzed.Additionally,a retrospective analysis was conducted on images of six patients who underwent clinical radiotherapy,and the images of them were obtained by using thoracic and abdominal scanning protocols.The sCT images,which were generated by deformable registrations on the basis of CBCT and iCBCT,were analyzed,and they were compared with located CT images,and their mean absolute error(MAE)and root mean square error(RMSE)were further quantitatively analyzed.Results:Compared to CBCT,iCBCT significantly reduced NPS(thoracic images reduced by 0.08,abdominal images reduced by 0.06).The UI values of thoracic images and abdominal images of iCBCT were respectively 0.37 and 0.28,and those of CBCT were respectively 0.65 and 0.39.The LCV values of thoracic images and abdominal images of iCBCT were respectively 0.67 and 0.56,and those of CBCT were respectively 0.93 and 0.90.The MTF50％were 0.28 lp/mm except abdominal image of iCBCT was 0.29 lp/mm.The resolution rate of high contrast between iCBCT and CBCT was basic consistency.The differences of similarity analysis of the generated sCT and located CT bases on CBCT and iCBCT was no significant(P＞0.05).Conclusion:The image quality of iCBCT is superior to conventional CBCT.The accuracy of CT value of generated sCT bases on CBCT and iCBCT can meet requirement,and both of them can be used in the dose calculation of adaptive radiotherapy.

Objective:To explore the reform path of clinical laboratory technical talents training in local universities under the background of "New Medicine".Methods:The present situation of medical laboratory technical personnel training under the background of "New Medicine" was analyzed, and the teaching mode, teaching platform and practical teaching were reformed according to the reality of Guizhou Medical University.Results:An open education system of "healthcare-education collaboration and academia-industry alliances" and the talent training mode of "three-oriented drive, four-sided integration" had been formed, which improved the training quality and provided a large number of qualified medical laboratory technical undergraduate talents to the grass-roots of Guizhou Medical System.Conclusion:The reform and practice of applied talent training in Guizhou Medical University can be used as a reference for local colleges and universities to educate applied medical laboratory technical talents.

To study an automatic plan(AP) method for radiotherapy after breast-conserving surgery based on TiGRT system and and compare with manual plan (MP). The dosimetry parameters of 10 patients and the evaluation of scoring table were analyzed, it was found that the targets dose of AP were better than that of MP, but there was no statistical difference except for CI, The V5, V20 and V30 of affected lungs and whole lungs in AP were lower than all that in MP, the Dmean of hearts was slightly higher than that of MP, but the difference was not statistically significant, the MU of AP was increase by 16.1% compared with MP, the score of AP evaluation was increase by 6.1% compared with MP. So the AP could be programmed and automated while ensuring the quality of the plan, and can be used to design the plans for radiotherapy after breast-conserving surgery.
Breast Neoplasms/surgery* ; Female ; Humans ; Mastectomy, Segmental ; Organs at Risk ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Intensity-Modulated

Methods:Two thousand standard sections images werre collected from 2 000 clinical retrospective pediatric hip ultrasound videos from January 2019 to January 2021. All standard sections were annotated by the annotation team through the self-designed software based on Python 3.6 environment for image cross-media data annotation and manual review standardization process with unified standards. Among them, 1 753 were randomly selected for training the deep learning system, and the remaining 247 were used for testing the system. Further, 200 standard sections were randomly selected from the test set, and 8 clinicians independently completed the film reading annotation. The 8 independent results were then compared with the AI results.Results:The testing set consists of 247 patients. Compared with the clinician's measurements, the area under the receiver operating characteristic curve (AUC) of diagnosing hip joint maturity was 0.865, the sensitivity was 76.19%, and the specificity was 96.9%. The AUC of AI system interpretation under Graf detailed typing was 0.575, the sensitivity was 25.90%, the specificity was 89.10%. The 95% LoA of α-angle determined by Bland-Altman method, of -4.7051° to 6.5948° ( Bias -0.94, P<0.001), compared with clinicians' measurements. The 95% LoA of β-angle, of -7.7191 to 6.8777 ( Bias -0.42, P=0.077). Compared with those from 8 clinicians, the results of AI system interpretation were more stable, and the β-angle effect was more prominent. Conclusion:The AI system can quickly and accurately measure the Graf correlation index of standard DDH ultrasonic standard diagnosis plane.

Objective:To explore the beam performance of GTR 360° PBS dedicated nozzle for IBA Proteus Plus proton system and evaluate the beam characteristics of PBS during acceptance test procedure (ATP) to meet the precision and safety requirements of clinical treatment.Methods:According to the requirements of acceptance tests, the beam tests of PBS mainly included: test of integrated depth dose (IDD), test of maximum field size at the maximum and minimum ranges, field uniformity and informative PBS tests for the GTR 360°, test of lateral dose uniformity in a single field uniform dose in a cube, test of longitudinal dose uniformity in a single field uniform dose in a cube, and test of monitor unit reproducibility and proportionality.Results:The maximum deviation measured of range, fall back accuracy and distal fall-off was 0.03 g/m 2, 0.01 g/m 2 and 0.078 g/m 2, respectively. Maximum field size at the maximum and minimum ranges was 30.2 cm×40.2 cm and 30.1 cm×40.1 cm, respectively. During the different gantry angles and ranges, the lowest γ passing rate of a pattern plan was 97%, the maximum deviation of the centrical beam spot size at the X and Y axes was -0.16 mm and -0.21 mm, and the worst symmetry was 0.80%. Compared with the centrical beam spot, the maximum size deviation of the other beam spots was 0.11 mm and 0.14 mm at the X and Y axes, and the maximum position accuracy deviation of the beam spot was 0.60 mm and 0.43 mm at the X and Y axes. The maximum deviation of lateral dose uniformity at at the X and Y axes was 0.55% and 0.80% in the high energy region, and 0.6% and 0.75% in the low energy region. The maximum deviation of longitudinal dose uniformity was 0.79% in the high energy region, and 2.22% in the low energy region. The monitor unit (MU) reproducibility factor was 0.106% and the maximum proportionality deviation was 0.67%. Conclusion:The dedicated nozzle of PBS has passed all the beam performance acceptance tests, which meet the requirements of all parameters, and the whole system yields relatively high accuracy, repeatability and good stability.

Objective: To study the dosimetric characteristics and plan quality of PTV-based intensity modulated proton radiotherapy (IMPT) and volumetric-modulated arc therapy (VMAT) plans for prostate cancer, so as to provide a reference for clinical application. Methods: A total of 10 prostate cancer cases were included in this retrospective study. IMPT and RapidArc plans were designed by RayStation and Eclipse TPS based on PTV, respectively. For each case, IMPT plans were generated using multiple field optimization (MFO) technique with two parallel-opposed lateral fields, whereas RapidArc plans were generated using double-arc technique (two full arcs). Final dose calculation of IMPT was conducted by pencil beam(PB) and Monte Carlo (MC) algorithm, respectively, with adopted data model from the pencil beam scanning (PBS) proton therapy system of IBA Protues Plus(IBA Group, Belgium); The data model originated from the linear accelerator of Varian Clinac iX (Varian Medical Systems, America) was used for RapidArc plans. Dosimetric parameters of DVH and dose distribution were used to compare the dose differences in targets and organs at risk (OARs) between these two treatment techniques. Results: For targets, HIs of PB-IMPT and MC-IMPT were slightly better than that of RapidArc , but CI of IMPT was slightly lower than that of RapidArc; D_1% of PB-IMPT was significantly better than those of MC-IMPT and RapidArc (Z=-2.805, -2.803, P<0.05). PB-IMPT and MC-IMPT achieved better protection than RapidArc on rectum V₃₀(Z=-2.191, -1.988, P<0.05)and D_mean(Z=-2.599, -2.497, P<0.05), bladder V₃₀(Z=-2.701, -2.701, P<0.05), V₄₀(Z=-2.395, -2.395, P<0.05)and D_mean(Z=-2.701, -2.701, P<0.05). There was no significant difference between PB-IMPT and MC-IMPT plans for prostate cancer, except for the D_1% [(73.86±67.34) Gy vs.(75.45±2.01) Gy] (RBE) and HI [(0.040±0.010) vs. (0.058±0.020)] of the target. Conclusions Both techniques can meet the clinical requirements, but IMPT showed significant dosimetric advantages compared with RapidArch by reducing the dose to OARs and improving the plan quality.