Objective:To investigate the performance of W2 plastic scintillator in megavolt photon and electron beams.Methods:The photon and electron beam energy provided by linear accelerator was used to collect data of the W2 scintillator. The parameters include the electrometer reading stability, W2 dose and dose rate linearity, and angular response. And the dose uncertainty of the W2 correction factors was also investigated.Results:The standard deviation of the electrometer reading stability was between 0.03 and 0.47. The linear regression factors of W2 dose were all 1.0; the maximum deviation of the dose rates was 0.61%. The Cerenkov light radiation correction factor(CLR) for 6 and 10 MV were 0.741 and 0.746, respectively, and the CLR for 6, 9, 12 and 15 MeV were 0.750, 0.753, 0.757 and 0.757, respectively. The maximum deviation of dose uncertainty for 15 MeV was 3.15%.Conclusions:The signal obtained by the blue and green channel was no angular dependence, the same as the high-energy electron beam, which verified that the Cerenkov radiation correction factor has good linearity. W2 plastic scintillator can be applied to non-coplanar radiotherapy dosimetry.

Supervision of teaching is of great significance to the substantive equivalence of "online" and "offline" teaching. Compared with the conventional supervision of offline teaching, supervision of online teaching has its particularity. The School of Medicine of Shanghai Jiao Tong University has formulated the online teaching supervision program, relying on the constantly improving supervision system in long-term practice and based on the quality control concept of OBE (outcomes-based education) which aims to improve the learning effect of students. The supervision program of online teaching includes full coverage of expert supervision, smooth feedback channels for students, prompt communication and solutions by management supervision, etc. And the effect of online teaching supervision on students' learning effect can be tested in practice. The effect of the online teaching has been investigated by the questionnaire survey. The results show that online teaching expert supervision has higher satisfaction and students learning effect is better, which illustrates that the online supervision program has played a positive role in teaching.

Objective To investigate the roles of ultrasound,laboratory methods,and genetic diagnostic techniques in screening and diagnosing fetuses with an unbalanced recombination of chromosome 18[rec(18)] due to parental pericentric inversion,and the relationship between rec(18) fetal phenotypes and their recombinant chromosomes.Methods We analyzed two pedigrees with pericentric inversion of chromosome 18 (including the fetuses and their parents) which received prenatal diagnosis and genetic counseling on March 2017 and March 2018 respectively at Xiamen Maternity and Children Health Care Hospital through karyotype analysis,chromosome microarray analysis(CMA) and fluorescence in situ hybridization (FISH).Literatures were retrieved from Scientific Citation Index,PubMed,China National Knowledge Infrastructure(CNKI) and Wanfang Data from 1970 to June 2018.The genetic counseling records,ultrasound and laboratory findings,pregnancy outcomes of families with pericentric inversion of chromosome 18 in this study and the included literatures were reported and analyzed.Results Non-invasive prenatal testing (NIPT) of one case indicated high risk of fetal trisomy 18 at 22 weeks of gestation.And the imaging examination indicated that fetus had interventricular septal defect and micrognathia at 24+2 weeks.Prenatal diagnosis confirmed that the fetal karyotype was 46,XY,rec(1 8)dup(18q) inv(18)(p1 1.32q12.1) pat,which was originated from his father whose karyotype was 46,XY,inv(1 8)(p1 1.32q12.1).In the other case,serum screening testing indicated high risk of fetal trisomy 18 at 12+3 weeks.Imaging examination indicated that fetus had thickened nuchal translucency at 13+3 weeks and bilateral choroid plexus cysts at 15+6 weeks.Prenatal diagnosis confirmed that the fetal karyotype was 46,XY,rec(18)dup(18q)inv(18) (p11.32q12.1) mat,which was originated from his mother whose karyotype was 46,XX,inv(18)(p11.32q12.1).Among the nine fetuses,including seven from five pedigrees reported in the literature retrieved and two from the two pedigrees we reported,seven showed abnormal soft markers or structures in ultrasound and three of the seven pedigrees had high risk of fetal trisomy 18.Conclusions Ultrasound screening is highly sensitive in detecting rec(18) fetuses,yet the association between ultrasound features and fetal karyotypes is not clear.The combination of multiple genetic analysis methods,including karyotype analysis,CMA and FISH,may be conducive to clarifying the types and sources of complex derived chromosomes.

Objective To assess the brain development of newborns with cardiac septal defects by MRI.Methods The brain MR images of 150 newborns with cardiac septal defects and 50 normal newborns were analyzed retrospectively.We evaluated the brain development by measuring the four indices of lateral ventricle:anterior horn index (F/F'),body index (D/D'),caudate nucleus index (C/C')and Evans index.Independent samples t test was used to compare the differences between the two groups,and the possible positive diagnostic cut-off points were calculated by using the nonparametric ROC analysis.Results There were no significant differences between the congenital heart disease group and the control group in the two indices:F/F'[(0.301±0.035)vs (0.296±0.031);t=1.035,P>0.05]and Evans index [(0.239±0.052)vs (0.233±0.025);t=0.778,P>0.05].The values of D/D'[(0.261±0.039)vs (0.234±0.032);t=3.873,P<0.05)] and C/C'[(0.138±0.018)vs (0.124±0.015);t=4.479,P<0.05]were significantly higher in the congenital heart disease group than in the control group.In the congenial heart disease group,the area under the ROC curve obtained by D/D'and C/C'were 0.698 and 0.750,respectively.The maximum Yuedeng index corresponding to the D/D'value and the C/C'value were 0.28 and 0.12,respectively. Conclusion The body index(D/D')and the caudate nucleus index(C/C')are sensitive to evaluate the differences of the brain volume between the newborns with cardiac septal defects and the normal newborns.It is helpful to find the abnormal brain volume when the value of D/D'is greater than 0.28 and the value of C/C'is greater than 0.12.

BACKGROUND:The assessment of asymmetric gait quality plays a pivotal role in guiding rehabilitation training;however,the link between gait quality and kinematic-kinetic gait parameters remains ambiguous. OBJECTIVE:To formulate a machine-learning model for evaluating gait quality based on gait parameters,identify factors sensitive to gait quality from asymmetric gait parameters,investigate the relationship between gait indicators and gait quality,and provide guidance for asymmetric gait training and rehabilitation. METHODS:An asymmetric gait database was established through the creation of asymmetric conditions.Kinematic and kinetic data were collected from 8 young and 8 elderly subjects(all male,right dominant population)during gait tests.Gait quality for each test data set was assessed using symmetry indices,resulting in the creation of a gait parameter-gait quality dataset.Utilizing the Random Forest algorithm,a gait quality evaluation model was developed and key quality parameter factors were identified through differential analysis.This model was iteratively refined.The model's performance was evaluated through 10-fold cross-validation,and its effectiveness was verified using the cross-validation dataset. RESULTS AND CONCLUSION:(1)A gradient test was designed to categorize gait quality into optimal,suboptimal,intermediate,and poor groups,with 759,329,133,and 125 instances,respectively.(2)The application of the Random Forest algorithm in gait quality assessment was explored.A relationship model was established between gait indicators and gait quality,yielding a predictive model accuracy of 95.99%.(3)The 13 main parameters significantly influencing asymmetric gait quality were identified through the Random Forest model's feature importance ranking.(4)An analysis of gait quality sensitivity factors using the 13 important parameters led to the identification of five key sensitivity indexes.The Random Forest model utilizing these sensitivity factors achieved a predictive accuracy of 94.20%.

Objective: To explore the clinical significance of a prenatal case with two small supernumerary marker chromosomes (sSMC) through identification of their origins. Methods: G-banding chromosomal karyotyping analysis were carried out on fetal amniotic fluid sample and peripheral blood samples from both patients. Fluorescence in situ hybridization (FISH) and single nucleotide polymorphism-array (SNP-array) were used to analyze the component and size of the sSMCs. Results: The karyotype of the fetus was determined as 47, XX, + mar[53]/48, XX, + 2 mar[31]/46, XX[14]. SNP-array has revealed four copies of chromosome 2q11.1q11.2 with a size of 2.6 Mb and three copies of 10p11.23q11.23 with a size of 20.6 Mb. The results was confirmed by FISH. Conclusion A rare chromosomal abnormality with two sSMCs was identified by combined karyotype analysis, SNP-array and FISH, which provided valuable information for prenatal diagnosis.

OBJECTIVE: To explore the nature of chromosomal abnormality in a fetus with nasal bone dysplasia and clarify its clinical effect. METHODS: Fetal chromosome karyotype was analyzed by G-banding. Single nucleotide polymorphism array (SNP-array) was used to detect the chromosomal copy number variations, and fluorescence in situ hybridization (FISH) was used to verify the result. RESULTS: Fetal karyotype analysis showed an unknown chromosomal fragment in 21q21 region. SNP-array discovered a 7.5 Mb duplication in the 21q22.12q22.3 region. FISH confirmed that the unknown fragment was derived from a 21q22.12q22.3 duplication. CONCLUSION Combined use of karyotype analysis, SNP-array and FISH has clarified the nature of chromosomal abnormality in a fetus with nasal bone dysplasia, which has enabled more accurate prenatal diagnosis and genetic counseling.

Objective:To understand the components, performance, acceptance test and quality assurance (QA) protocols of the new Varian Halcyon accelerator through the procedures of installation product acceptance (IPA).Methods:Per Varian IPA protocol, TG-142 for LINAC and TG-148 for tomotherapy QA protocols, the software license, safety interlock, mechanical accuracy, dosimetric performance and imager system were checked thoroughly. Some parameters were benchmarked to the conventional TrueBeam system.Results:The system has been fully licensed. Safety interlock was normal. Mechanical accuracy: The maximum deviation of beam stability per gantry rotation was 1.13%. The size of isocenter was>0.59mm. The offsets of MV imager, collimation rotation and absolute gantry rotation were 0.09mm, -0.21° and 0.11°, respectively. The maximum offsets of couch, virtual-to-isocenter were 0.15mm (vertical) and -0.04mm (vertical), respectively. Beam performance: The depth deviation of maximum dose was 0.1cm. The offset of percentage depth dose at 10cm was 0.5%. The maximum deviations of off-axis-intensity, symmetry, and repeatability were 0.9%, 0.94% and -0.44%, respectively. MV imager: The dark field mean pixel value, noise, corrected pixels, defective lines, sensitivity and linearity disparity of dose were 614, 4.4, 3626, 0, 19177, and 0.47%, respectively. All values were within the range of tolerance. Visual check of contrast resolution and small object detection was all satisfactory.Conclusions:Without Halcyon-specific TG report or guidelines, manufacture-provided IPA manual can be helpful with the installation of acceptance and QA protocols. IPA has been successfully performed for Halcyon at Peking University Cancer Hospital. The automated workflow improves the clinical efficiency by simplifying the operations.

Objective To compare two pretreatment plan QA methods for HalcyonTM accelerator using Portal Dosimetry (PD),and PTW OCTAVIUS 1500 detector array + Octagonal phantom (Oct 1500)respectively.Methods Parallel measurement-based pretreatment QA using two methods was performed for 22 IMRT/VMAT plans (74 fields) that have been used to treat 20 patients recruited in the Halcyon clinical trial.Several γ 2D comparisons were also applied to provide guidelines for Halcyon planning QA.Results Using Oct1500 method,the γ 2D passing rates for 74 fields in 22 Plans were 95.26±3.59,95.01±3.62 (Local Dose),99.05± 1.35,98.57± 1.96 (Max Dose) respectively.Two-related samples non-parametric tests suggested that the differences between the evaluation criteria were of statistical significance (Z =-7.220,-4.108,P＜0.05).For PD method,the γ 2D passing rates were 84.11％ ± 1.35％ (1 mm/1％),99.07％± 1.35％ (2 mm/2％),and 99.86％ ± 1.35％ (3 mm/3％).Two-related samples non-parametric tests suggested that the differences between evaluation criteria of PD method were statistically significant (Z =-7.475,-7.475,-6.906,P＜0.05).For 74 fields and max dose,3 mm/3％ evaluation criteria,two-related samples non-parametric tests suggested that the differences between PD and Oct1500 method were statistically significant (Z=-5.072,P＜0.05).Conclusions Both methods can be used for Halcyon pretreatment plan QA.PD is superior to Oct1500 with respect to efficiency and spatial resolution-induced verification accuracy.The criteria of 2 mm/2％ for PD,and Max Dose/3 mm/3％ for Oct1500 was suggested.