Objective:The purpose of this paper is to introduce a method of using compensate angles to eliminate rotation set-up errors without six-degree of freedom couch. Methods: To detect six-degree of freedom set-up errors, cone-beam computed tomography (CBCT) scans were acquired. These set-up errors were defined as a matrix to transform from accelerator coordinate system to patient coordinate system. Two independent vectors were defined to describe angles of gantry, collimator and couch in accelerator machine. Transformation of vectors were determined by transformation matrix and re-calculated back to the machine angles. Results:It was found that compensate angles can fully corrected the rotation angles in set-up with limited time consuming. It is feasible to implement compensate angles in routinely radiation procedure. Conclusion:With this method, it is possible to implement the complete corrections of set-up errors in radiotherapy without six-degree of freedom couch and it is convenient in operation as well.

OBJECTIVE:To observe the protective effect of ketamine and dexamethasone on lung injury in esophageal cancer thoracotomy. METHODS:60 patients with one-lung ventilation thoracotomy were randomly divided into 4 groups:blank group (group S),ketamine group(group K),dexamethasone group(group D)and ketamine and dexamethasone group(group KD)by number. After surgery,the patient-controlled epidural anaigesia (PCEA) was used to record the concentrations of IL-6,IL-8, TNF-α with the time point of preoperative 30 min (T0),60 min after one-lung ventilation (OLV)(T1),120 min after the OLV (T2),2 h after restore double-lung ventilation(T3),the changes of respiratory index(RI)in blood gas analysis and the analgesic effect and adverse reactions in 48 h after treatment. RESULTS:There was no obvious difference between the blood pressure and heart rate in 4 groups. Compared with T0,the RI values in T1,T2 and T3 were increased;compared with group KD,the RI values in T2 and T3 in group K,group D and group S were increased;compared with T0,the concentrations of IL-6 and IL-8 in T1,T2 and T3 were increased(P<0.05);compared with group S,the concentrations of IL-6 and IL-8 in T1,T2 and T3 in group D,group F and group KD were decreased(P<0.05);compared with group KD,the concentrations of IL-6 and IL-8 in T2 and T3 in group D and group K were higher(P<0.05),there was no significant difference between group D and group K(P>0.05)and the con-centration of TNF-α in 4 groups was lower than minimum detectable concentrations;compared with group KD,the scores of anal-gesia visual analogue scale(VAS)and Prince-Henry in postoperative 48 h in group K and group S were higher(P<0.05);com-pared with group D,group S and group K,the total number of press PCEA and the total amount of analgesic in group KD were de-creased (P<0.05) and the incidence of postoperative nausea was low (P<0.05);there was no significant difference in the inci-dence of postoperative delirium in 4 groups (P>0.05). CONCLUSIONS:Ketamine and dexamethasone can reduce the release of inflammatory mediators,decrease the RI values,increase the analgesia effect and has certain protective effect on lung injury.

Objective To study the application of correlation statistical analysis model in IMRT planning optimization. Methods A correlation statistical analysis model was established. IMRT plans of 5 prostate cancer patients were randomly chosen from the ADAC Pinacal 7.6 version planning system. The beam parameters, objective functions of the target area and optimization parameters of the primary plan were kept unchanged. The main optimization parameters including EUD parameter a,weight (w) and EUD_(max) of OAR were adjusted in optimization procedure successively. The correlation analysis (CF) and optimization efficiency analysis (OF) were carried out on the results of the optimization. The optimal value of parameters (MORt{}) with the best dose distribution was obtained and substituted in the corresponding primary plan.After optimization, the dose distributions of the two IMRT plans were compared. Results There were signif-icant differences with different optimization methods. The EUD parameter a and weight factor (w) almost had no effect on volume dose of OAR (OF < 0.01), though had obvious effect on the maximum dose and mean dose (OF≈1). The CF analysis showed that the correlation between the PTV ( V_(95)) volume and OAR dose was different when the EUD parameter a and w were applied for optimization. Meanwhile, the difference was proportional to the distance between the target area and OAR. The mean dose of OAR was decreased and the mean dose of PTV was more close to the prescription dose when the optimization parameters of the prima-ry plan were substituted with MOR{a} ,MOR{w} and MORt{EUD_(max)}. Besides, the DVH and isedose dis-tribution of the secondary plan were better. Conclusions The correlation statistical analysis model can be used to accurately determine the scope of optimization parameters in the IMRT planning procedure in prostate cancer, and an IMRT plan which fulfils the clinical requirement can be obtained efficiently.

Objective To develop a beam orientation optimization algorithm for the gantry orientation in three-dimensional conformal radiotherapy(3 DCRT).Methods Patients' data were imported from the Pinnacle v 7.2 treatment planning system.including the DICOMRT and dose distribution files.These imported files were merged using a uniforiB coordinate system.The algorithm determined the optimized beam weight for each beam group and optimized the beam orientation with genetic algorithm.The optimized parameters,including the optimized beam orientations and weights,were exposed back to the Pinnacle v 7.2 to compare with the conventional 3DCRT plan.The optimized algorithm was implemented with our in-house program. The dose distributions, the DVH diagram and the conformity index of two lung cancer patients were compared. Results for the two lung cancer patients,the conformity index of the optimized plan(0.59 and 0.7)was higher than the conwentional 3DCRT plan(0.36 and 0.58).The maximum dose in spinal cord was reduced by 17.8%and 22.4%,the lung V20 reduced by 3.12%and 4.35%,and V30 reduced by 4.47%and 1.49%.For the brain tumor patient. the dose of lens and eyes was also decreased significantly. Conclusion This beam orientation optimization can be used as an assistant planning tool.

Objective To develop a brachtherapy (BT) dose calculation program based on AAPM TG-43UI formula.With this program we can combine the dose result of external beam radiotherapy (EBRT) and BT together which is calculated by the different treatment planning TPS.Methods BT treatment data, such as source parameter, dwelling position and dwelling time, are retrieved from Nucletron Plato planning system and converted to ADAC planning system coordinate.The BT 3D dose distribution is re-calculated as well.Then the 3D dose distribution is exported to ADAC planning system.In that way, ADAC planning system can display either the EBRT dose or the BT dose and the combined dose can be calculated, displayed and evaluated as well.Results BT dose calculation result of our program which based on AAPM TG-43UI formula is identical with which of Plato (<0.1%).Furthermore, the BT dose can be transfer to the ADAC easily and the dose distributions of combined therapy can be merged in ADAC.Conclusions Our program can be used to combine the dose result of EBRT and BT from different TPS.

Objective To explore the set-up errors of position fixation with simple perforated foam pad in colorectal cancer radiotherapy and their causes as well as the improvement measures.Methods Sixty cases of color-ectal cancer patients undergoing radiotherapy were collected.Prone position was adopted with the position fixed by perforated foam pad and membrane.CBCT imaging was taken weekly before treatment,setup errors were corrected if necessary.Errors throughout the course of treatment for each patient were recorded and compared between patients, followed by analyzing the reasons of errors.Results Before calibration,the maximum errors on the direction of left and right (X-axis),front and back (Z),upside and downside (Y)in these 60 patients were 0.5cm,0.9cm and 0.7cm respectively with the average errors of (0.22 ±0.03)cm,(0.38 ±0.03)cm and (0.27 ±0.04)cm respec-tively.Conclusion The method of applying perforated foam pad and thermoplastic mask in colorectal cancer radio-therapy is currently the most commonly used in the clinical position fixation techniques,by which the small intestine, bladder and other pelvic tissues can be well protected.Due to poor comfort prone position,it is necessary to further improve perforated foam pad through improving the quality of the foam pad,thus improving patients comfort and posi-tioning repeatability and reducing position fixation errors.

Objective To compare the dosimetric differences between free-hand method and virtually optimized method for implanting needles in intracavitary and interstitial combined brachytherapy (IC/IS BT) of cervical cancer,and to explore the improvement space of the existing interstitial brahcytherapy plan.Methods High-dose-rate cervical cancer IC/IS BT plans (short for Treatment-Plan) of 18 cases were retrospectively analyzed.For each treatment plan,Nucletron Oncentra 3D brachytherapy planning system was utilized to redesign the virtually optimized insertion method IC/IS BT plan (short for Optimized-Plan).Dose volume histogram was adopted to evaluate the dose distribution in high-risk clinical target areas and exposure dose to organ at risk (OAR).The plan execution efficiency between two plans was also assessed.Results Comparing these two plans,the differences in conformity and uniformity of dose distribution of the target area were statistically significant (P=0.000,0.008).The differences of D0.01 cm3,D1 cm3,D2 cm3 and D5 cm3 in bladder,rectum,sigmoid and small bowel were all statistically significant (all P＜0.05).Optimized-Plan could reduce the D2 cm3 of bladder,rectum,sigmoid and small bowel by 60.41,36.43,27.53 and 12.43 cGy,respectively.The execution time for the Treatment-Plan and Optimized-Plan were (857.92±243.39) s and (804.53±239.13) s with statistical significance (P＜0.001).Conclusions Compared with the free-hand method,virtually optimized method yields more conformable coverage of the target area and more uniform dose distribution.At the same time,the doses of each OAR are reduced to different degrees and the execution time of the plan is also shortened.

Objective: To investigate the willingness to receive measles-containing vaccine (MCV) and its influencing factors among healthcare workers in the Yangtze River Delta region, so as to provide the evidence for improving the measles-containing vaccination rate Methods: Healthcare workers were sampled from 19 medical institutions in each of Shanghai Municipality, Jiangsu Province, Zhejiang Province and Anhui Province for questionnaire surveys using a multi-stage stratified convenience sampling methods from July 2020 to March 2021. Participants' gender, age, educational level, professional title, measles-containing vaccination, awareness of MCV and willingness to receive MCV were collected, and the factors affecting the willingness to receive MCV were identified among healthcare workers using a multivariable logistic regression model. Results: Totally 1 403 questionnaires were allocated, and 1 394 valid questionnaires were recovered, with an effective recovery rate of 99.36%. The respondents included 327 men and 1 067 women, with a male to female ratio of 1∶3.26, and 64.35% (897) were at ages of 31 to 50 years. There were 1 005 respondents with a bachelor degree (72.09%), 765 with middle and senior professional titles (54.88%), 676 with a history of measles-containing vaccination (48.49%), 1 176 with willingness to receive MCV (84.36%) and 218 without willingness to receive MCV due to convenience of vaccination (30.73%) and cost (19.27%). Multivariable logistic regression analysis showed that region (Zhejiang, OR=1.613, 95%CI: 1.054-2.470; Anhui, OR=2.058, 95%CI: 1.259-3.363), and no history of measles (OR=2.219, 95%CI: 1.302-3.781) were factors improving the willingness to receive MCV among healthcare workers, and hospital level (secondary, OR=0.483, 95%CI: 0.306-0.763; tertiary, OR=0.251, 95%CI: 0.160-0.394), history of measles-containing vaccination (no, OR=0.262, 95%CI: 0.172-0.399; unknown, OR=0.386, 95%CI: 0.266-0.559), and unawareness of MCV knowledge (OR=0.208, 95%CI: 0.081-0.536) were factors inhibiting the willingness to receive MCV among healthcare workers. Conclusions The willingness to receive MCV correlates with region, history of measles, hospital level, history of measles-containing vaccination and awareness of MCV knowledge among healthcare workers in the Yangtze River Delta region.

Conformal radiation therapy using multi-leaf collimator (MLC) is considered as a conventional technology in the hospital nowadays. However the stepped leaf edge caused by the finite width of the leaves could influence the conformality that could be achievable. In this paper, the effect produced by rotating the collimator angle on the conformality was investigated. A method, in which multiple MLC fields of various rotation angles are applied, has been proposed to have the targets be more uniformly irradiated and thus to eliminate the cold spots on the targets and hot spots in normal tissues. By simulation, it has been shown that the multiple MLC field method can eliminate the stepped leaf edges and improve the conformality significantly, moreover, the PTV can receive a more uniform delivery with cold spot eliminated.
Humans ; Radiometry ; methods ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; instrumentation ; methods ; Radiotherapy, Conformal ; methods

Objective: To study a lung dose prediction method for the early stage non-small cell lung cancer (NSCLC) treated with stereotactic body radiotherapy based on machine learning algorithm, and to evaluate the feasibility of application in planning quality assurance. Methods: A machine learning algorithm was utilized to achieve DVH prediction. First, an expert plan dataset with 125 cases was built, and the geometric features of ROI, beam angle and dose-volume histogram(DVH) parameters in the dataset were extracted. Following a correlation model was established between the features and DVHs. Second, the geometric and beam features from 10 cases outside the training pool were extracted, and the model was adopted to predict the achievable DVHs values of the lung. The predicted DVHs values were compared with the actual planned results. Results: The mean squared errors of external validation for the 10 cases in mean lung dose (MLD)MLD and V₂₀ of the lung were 91.95 cGy and 3.12%, respectively. Two cases whose lung doses were higher than the predicted values were re-planned, and the results showed that the the lung doses were reduced. Conclusion It is feasible to utilize the anatomy and beam angle features to predict the lung DVH parameters for plan evaluation and quality assurance in early stage NSCLC patients treated with stereotactic body radiotherapy