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Objective:To explore the value of fast susceptibility weighted imaging (SWI) generated by a deep learning model in assessment of acute ischemic stroke (AIS).Methods:From January 2019 to January 2021, 118 AIS patients [75 males and 43 females, aged 23-100 (66±14) years] who underwent MR examination and SWI sequence scanning within 24 h of symptom onset in the First Medical Center of PLA General Hospital were retrospectively analyzed. MATLAB ′s randperm function was used to divide 118 patients into a training set of 96 cases and a test set of 22 cases at a ratio of 8∶2. Fourty-seven AIS patients [38 males and 9 females, aged 16-75 (58±12) years] from one center of a multicenter study were selected to build the external validation set. SWI image and filtered phase image were combined into complex value image as full sampling reference image. Undersampled SWI images were obtained by retrospective undersampling of reference fully sampled images, and the undersampling multiple was five times which could save 80% of the scanning time, then the complex-valued convolutional neural network (ComplexNet) was used to develop reconstruct fast SWI. Interclass correlation coefficient (ICC) or Kappa tests were used to compare the consistency of image quality and the diagnostic consistency for the presence of susceptibility vessel sign (SVS), cerebral microbleeds and asymmetry of cerebral deep medullary veins (DMVs) in AIS patient on fully sampled SWI and fast SWI based on ComplexNet.Results:In test set, score of image quality was 4.5±0.6 for fully sampled SWI image and 4.6±0.7 for fast SWI based on ComplexNet, and coefficient was excellent (ICC=0.86, P<0.05). Full sampling SWI had good agreement with fast SWI based on ComplexNet in detecting SVS (Kappa=0.79, P<0.05), microbleeds (Kappa=0.86, P<0.05), and DMVs asymmetry (Kappa=0.82, P<0.05) in AIS patients. In the external validation set, score of image quality was 4.1±1.0 for fully sampled SWI image and 4.0±0.9 for fast SWI based on ComplexNet, and coefficient was excellent (ICC=0.97, P<0.05). Full sampling SWI had good agreement with fast SWI based on ComplexNet in detecting SVS (Kappa=0.74, P<0.05), microbleeds (Kappa=0.83, P<0.05), and DMVs asymmetry (Kappa=0.74, P<0.05) in AIS patients. Conclusions:Deep learning techniques can significantly accelerate the speed of SWI, and the consistency of image quality and detected AIS signs between fast SWI based on ComplexNet and fully sampled SWI is good. The fast SWI based on ComplexNet can be applied to the radiographic assessment of clinical AIS patients
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Objective:To investigate the manpower allocation and scientific research level of radiotherapists in radiotherapy units in mainland China, aiming to provide reference for the construction of radiotherapist teams.Methods:The questionnaire was designed and produced by the organizer, released in the professional committee, professional group and other channels of the radiotherapist industry, and filled out by the technical person in charge of the radiotherapy unit through the online questionnaire survey. The collection time started from mid-May 2021 to mid-June 2021.Results:A total of 558 effective questionnaires filled out by radiotherapy units. The radiotherapy institutions participating in the survey had a total of 5500 radiotherapists, including 3702 males and 1798 females, 3754 with a bachelor's degree, 371 who are currently studying or have obtained a master's degree, 21 who are currently studying or have already obtained a doctoral degree, 3642 with junior or lower titles, 1580 with intermediate titles, and 278 with senior titles. In 2020, radiotherapists from 193 units published articles, those from 81 units received project funding, and those from 56 units obtained patent authorization, and those from 15 units had scientific research transformation. The participating units had a total of 1080 large-scale radiation therapy equipment. In 2020, the daily average number of radiotherapy patients was 47 900, the average daily load of accelerator patients was 44.35, and the average workload index per capita was 8.71. The average daily radiotherapy patients in county-level or below, city-level, and provincial-level institutions were 25.78, 65.68, and 173.76, respectively, and the per capita workload index was 5.22, 8.09, and 10.11.Conclusions:Compared with the 2019 survey, the educational background of radiotherapists in mainland China has been improved, and the title structure has been optimized to a certain extent, and the workload of large-scale radiotherapy units is larger than that of grass-roots units.
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Objective:To investigate and analyze the basic occupational situation of Chinese radiotherapists and to provide references for the development and construction of the radiation therapist team in China.Methods:Between May 7, 2021 and June 15, 2021, this survey was conducted using a self-designed questionnaire, which was distributed and collected in the form of online survey to conduct a statistical analysis of the basic situation of radiotherapists in 30 provincial-level administrative regions in China.Results:A total of 2 928 valid questionnaires were collected from 30 provincial-level administrative regions. The ratio of male to female and average age of the participants were 69∶31 and 35 years (18-65), respectively. According to the survey result, 84.7% of the participants came from Tertiary A-level hospitals. In terms of educational background, the participants with doctoral, master, undergraduate, junior-college, and technical-secondary degrees accounted for 0.2%, 6.9%, 76.6%, 14.9%, and 1.4%, respectively. In terms of title, full senior technologists, associate senior technologist, technologist-in-charge, technologist, and technician in the participants accounted for 0.5%, 5.8%, 32.5%, 52.2%, and 8.2%, respectively. The participants with years of employment of 0-, 5-, 10-, 20-y accounted for 33.74%, 25.79%, 25.51%, and 14.96%, respectively. The majors of the participants included medical imaging/imaging technology (45.9%), clinical medicine (19.1%), and biomedical engineering (11.9%).Conclusions:Chinese radiotherapists tend to be younger and are rapidly increasing in number. Employers should attach importance to the career planningand continuing education of radiotherapists to improve their technical skills, in order to fully satisfy the demand for radiotherapists in the new era.
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Objective:To compare the difference between active breathing coordinator (ABC) technique and free breathing (FB) mode combined with bodyfix stereotactic radiotherapy (SBRT) for chest tumors.Methods:40 thoracic tumor patients receiving SBRT were randomly selected and divided into the ABC technique group and FB model group. After fixation with bodyfix fixing devices in two groups, cone-beam CT (CBCT) scan images before each SBRT were matched with the plan reference images. The setup errors in the left-right (LR), superior-inferior (SI) and anterior-post (AP) directions were obtained. Then, the setup errors were corrected. SBRT was performed and split intra-fraction CBCT was conducted simultaneously, which was repeated until the end of treatment.Results:In the ABC technique group, the setup errors in the LR, SI and AP directions were (0.25±0.21) cm, (0.28±0.21) cm, and (0.21±0.24) cm, significantly less compared with (0.31±0.22) cm, (0.32±0.21) cm and (0.37±0.23) cm in the FB model group (all P<0.05). The V 30Gy of the heart, the V 20Gy and V 30Gy of the lung in the ABC technique group were significantly less than those in the FB model group (0.31%∶7.35%; 24.5%∶32.9%; 19.5%∶25.8%, all P<0.05). Conclusions:ABC technique combined with bodyfix fixation device may be superior to FB mode in SBRT for chest tumors, which remains to be validated by subsequent studies with large samples.
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OBJECTIVE@#To investigate the pre-treatment preventive maintenance and quality control procedure of MRI system and transcranial MRI-guided focused ultrasound (TcMRgFUS) treatment system by monitoring quality control of these two systems.@*METHODS@#The general performance index and image quality control index of MRI system, as well as the quality assurance program of TcMRgFUS EXABLATE 4000 system were tested and recorded.@*RESULTS@#The general performance index and image quality control index of MRI system met requirements.@*CONCLUSIONS@#Through system detection, the system performance could be monitored, ensuring the accuracy and safety of surgery.
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Hyperthermia, Induced , Magnetic Resonance Imaging , Phantoms, Imaging , Quality ControlABSTRACT
Objective To compare the dosimetric parameters between the use of Tandem and Ring (TR;Nucletron#090.617) or Tandem and Ovoid (TO;Nucletron#189.730) applicators during three-dimensional (3D) high-dose rate (HDR) brachytherapy (BT) for cervical cancer.Methods The records of 40 cervical cancer (ⅡB-ⅣA) patients treated with 3D-image-guided HDR-BT were reviewed.Of these 40 patients, 20 were treated with the TO applicator, and 20 with the TR applicator.The D100% and V150% of the clinical target volume (CTV) and the D2 cc of organs at risk (OAR)(the rectum, bladder, and small intestine) during 3D-HDR-BT using TO and TR were compared using the independent sample t-test.ResultsOverall metrics:CTV volume:66.04±13.86 cm3(TR) vs.65.67±15.08 cm3(TO)(P=0.052);CTV D100:3.71±0.34 Gy (TR) vs.3.37±0.49 Gy (TO)(P=0.016);CTV V150%:0.54±0.02(TR) vs.0.56±0.04(TO)(P=0.034);rectum D2 cc:3.38±0.30 Gy (TR) vs.2.95±0.80 Gy (TO)P=0.037);bladder D2 cc:4.33±0.39 Gy (TR) vs.2.93±1.27 Gy (TO)(P=0.00);and small ntestine D2 cc:3.04±1.02 Gy (TR) vs.3.41±0.57 Gy (TO)(P=0.171).Conclusions TR has better CTV coverage than TO during 3D HDR brachytherapy for cervical cancer.In addition, D2 cc of the rectum and bladder were both igher with TR than with TO, though there is no significant dosimetric difference in the small intestine between the two applicators.Therefore, tumor location, extent of invasion, and vaginal conditions should be considered when selecting the suitable pplicator for the treatment of cervical cancer.
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Objective To compare the ExacTrac X-ray and CBCT image guide system for the head and neck cancer patients in radiotherapy. Methods Twenty head and neck cancer patients were randomly chosen and divided two Group. In group A ( 10 patients) ,the cross X-ray radiation photos were matched with the DRR after positioning with the infrared markers. Obtain the setup errors on three directions and rotation errors. Then adjustment of error with 6D treatment bed,record time set-up and registration. In group B ( 10 patients) ,the CBCTimages were matched with reference CT data after manual positioning. Obtain the setup errors on three directions and around the vertical axis direction errors. Then adjustment of error,record the time of set-up and registration. Groups were compared using the paired t-test. Results For group A and B group,the translation errors were (0.59±0. 25) mm,(0.62±0. 25) mm,(1.56±0. 28) mm,and (0.52± 0. 31) mm,(0.74±0. 17) mm,(1.58±0. 34) mm on horizontal,vertical,up-down directions,respectively (P=0.43,0.21,0.90).For group A,the rotation errors were (0.54±0.17)°,(0.72±0.27)°,(0.44± 0. 22)°,respectively;with (1.26±0. 33)°on vertical directions on B group (P=0. 01).The time of set-up registration on group A was significantly less than group B ( 108. 0 s vs . 165. 8 s , P= 0. 00 ) . Conclusions For the head and neck cancer patients in raditherapy,the image guide systems is feasible. The rotation errors of ExacTrac X-ray slightly less than CBCT.The time of set-up and registration of ExacTrac X-ray significantly less than CBCT,but the image resolution of ExacTrac X-ray inferior for CBCT.
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Objective To develop double-arc volumetric modulated arc therapy ( VMAT) plans using standard phantom and standard target volume in AAPM119 report, and to investigate the dosimetric parameters of Agility and MLCi2 leafs according to the requirements for target dose in AAPM119 report. Methods The Cshape, Head and Neck, Prostate, and Multitarget structures for standard target volume delineation in AAPM119 report were used.The Elekta Agility multi-leaf collimator was used to develop plans, and then with other parameters remaining unchanged, Elekta MLCi2 was used for plan optimization and dose calculation.The target dose in AAPM119 report was used as the standard to analyze the differences in target volume and dose-volume parameters of organs at risk between the four structures for target volume delineation.Results According to the mean dose in AAPM119 report, in the Cshape, Head and Neck, and Multitarget target volumes, the radiotherapy plans developed with Agility had better dosimetric parameters compared with those developed with MLCi2.In the prostate target volume, the radiotherapy plans developed with MLCi 2 had better dosimetric parameters compared with those developed with Agility .Conclusions With the structures for target volume delineation, plan designing personnel, designing parameters, and evaluation criteria remaining the same, Elekta Agility can achieve the dose target better than Elekta MLCi2 in the aspect of strict dose limit.
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Objective To study the impact of respiratory frequency and amplitude of patients with the thoracic or abdomen tumor on 4DCT' s reconstructed image.Methods 75 thoracic or abdomen tumor patients who performed a scanning with belly belt-type respiratory gating on 4DCT between November 2012 to March 2013 in our hospital were retrieved.Reviewed their respiratory frequency,amplitude and fault distance of 4DCT' s reconstructed image and analyzed the correlation fault distance of the reconstructed image.The correlation analysis was used by bivariate Spearman method.Results Among these reconstructed images,fault distance more than 6 mm could be seen in 11 cases,fault distance ranging from 3 mm to 6 mm could be found in 46 cases,and distance less than 3 mm could be detected in 18 case.Respiratory frequency correlated significantly with the amplitude (rs =0.369,P =0.000);the respiratory rate had a tight association with the fault distance of the reconstructed image (r,=0.273,P=0.018);and respiratory amplitude was associated obviously with the fault distance of the reconstructed image (r,=0.696,P=0.000).Conclusions Both 4DCT reconstructed image and respiratory amplitude are significantly correlated to the continuity of the respiratory frequency.The smaller the respiratory frequence and amplitude change are,the better continuity will be.
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Objective To compare set?up error and the positioning and error correction time between the infrared markers automatic positioning+ ExacTrac ( A) and the manual positioning+ cone?beam computed tomography ( CBCT) image?guided radiotherapy ( IGRT) ( B) in intensity?modulated radiotherapy ( IMRT) for lung cancer. Methods A total of 20 patients with lung cancer were randomly divided into Group A and Group B. In Group A, after automatic positioning, a group of orthogonal X?rays images were taken using kV X?rays, which matched digitally reconstructed radiographs to obtain errors before correction. In group B, after manual positioning, images were taken using CBCT, which matched reference computed tomography images to obtain errors before correction. The positioning and error correction time was recorded in both groups. After error correction, errors after correction were obtained in each group using IGRT. Between?group comparison was made using the paired t test. Results The errors in lateral, longitudinal, vertical, and spinning vertical directions were significantly reduced after correction in both Group A and B (A:1.8±1?3 vs. 0.4±0?1, P=0?000;2.7±1?9 vs. 0.5±0?1, P=0?000;2.8±1?7 vs. 0.4±0?1, P=0?000;1.6±1?0 vs. 0.3±0?9, P=0?000;B:2.6±1?9 vs. 0.5±0?5, P=0?000;3.1±2?5 vs. 0.6±0?6, P=0?000;2.1±1?8 vs. 0.5±0?5, P=0?000;0.9±0?7 vs. 0.3±0?1, P=0?000). There were no significant differences in errors after correction between Group A and Group B (0.4±0?1 vs. 0.5±0?5, P=0?204;0.5±0?1 vs. 0.6± 0?6, P=0?257;0.4± 0?1 vs. 0.5± 0?5, P=0?518;0.3± 0?9 vs. 0.3± 0?1, P=0?755 ) . However, the positioning and error correction time in Group A was significantly shorter than that in Group B (199.1±16?2 vs. 315.2±13?7, P=0?000). Conclusions The application of ExacTrac or CBCT IGRT can substantially reduce set?up errors and improve set?up accuracy in IMRT. In addition, the application of the ExacTrac system can substantially shorten the positioning and error correction time.
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Objective To study the ExacTrac X-ray image guide system for patients with head and neck cancer.Methods Ten patients were chosen foe this study.It was immoblized using the head mask and frame fixtures.The two KV X-ray units were matched with the digitally reconstructed radiographs after positioning with the infrared markers.Then the setup errors on x (horizontal axis),y (vertical axis) and z (up-down) directions and rotation errors were obtained.Paired t-test between any two direction difference errors.Results The setup errors with ExacTrac X-ray image guide system for the patients in x,y,z directions and rotation errors were (0.57 ± 0.24) mm,(0.68 ± 0.19) mm,(1.54 ± 0.29) mm,(0.54 ±0.13) °,(0.60 ± 0.23) °,(0.51 ± 0.15) °.The z-axis direction have slightly larger error (P =0.02,0.01).The others have not statistical significance (P =0.06,0.10-0.41).Conclusions To use ExacTrac X-ray image guide system cooperating with the six degree of freedom treatment couch in image guided radiotherapy for is feasible,the motion errors ＜ 2 mm,the rotation errors ＜ 2°.Reduced of the setup errors with replace the sphere or to reduce pollution of the sphere,improve the accuracy,it could provide a better quality assurance in radiation therapy.
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Objective To compare the accuracy of blood volume perfusion imaging (perfusion CT)with contrast enhanced 64-slice spiral computed tomography (CECT) in the evaluation of gross tumor volume (GTV) and clinical target volume (CTV) using rabbits with VX2 brain tumor. Methods Perfusion CT and CECT were performed in 20 rabbits with VX2 brain tumor. The GTV and CTV calculated with the maximal and minimal diameter of each tumor in the blood volume (BV) maps and CECT were measured and compared to those in pathological specimens. Results The mean value of the maximal and minimal diameter of GTV was (8.19 ± 2. 29) mm and (4.83 ± 1.31) mm in pathological specimens, (11.98 ±3.29) mmand (7.03±1.82) mm in BV maps, while (6.36±3.85) mm and (3.17±1.93) mm in CECT images, which were significantly different (pathological specimen vs. BV map, t = 7. 17,P =0. 000;pathological specimen vs. CECT, t = 8.37, P = 0. 000, respectively). The mean value of the maximal and minimal diameter of CTV in pathologic specimens was (12.87 ± 3.74) mm and (7.71 ± 2. 15) mm, which was significantly different from that of GTV and CTV in CECT (t = - 3. 18, P = 0. 005 and t = - 4. 24, P =0. 000;t= -11.59,P=0.000 and t= -9.39,P=0.000), while similar with that of GTV in BV maps (t = - 1.95,P = 0. 067; t = - 2. 06, P = 0. 054). For CECT, the margin from GTV to CTV was 81.83% ±40.33% for the maximal diameter and 276.73% ± 131.46% for the minimal. While for BV maps, the margin was 7.93% ± 17. 84% and 12.52% ± 27. 83%, which was significant different from that for CECT images (t=7.36,P=0. 000 and t= -8.78,P=0.000). Conclusions Compared with CECT, the BV map from 64-slice spiral CT peffusion imaging might have higher accuracy in target volume delineation for brain tumor.