Dose reconstruction of electronic portal imaging device based on calibration and calculation / 中国医学物理学杂志

A dose reconstruction algorithm for electrionic portal imaging device(EPID)based on calibration and calculation is developed.The raw data of EPID in continuous acquisition mode are corrected for dark field and gain,and the gray level features of bright field are used to determine the field boundary.Subsequently,MU calibration,off-axis calibration and field size calibration are performed on the EPID data,and dose reconstruction is carried out based on the calibrated superimposed flux and the Monte Carlo model of the linac head.Nine cases of IMRT plans are selected for verification and measurement using EPID and MapCheck separately,and the passing rates between the two tools are compared under different gamma criteria(3%/3 mm and 2%/2 mm).For a planned case,the average passing rates of multiple cases verified by MapCheck under the two criteria were 99.02%±1.28%and 90.84%±4.49%,and the average passing rates of the EPID reconstruction models were 98.86%±1.19%and 91.39%±4.80%.Compared with MapCheck,the EPID reconstruction algorithm based on calibration and calculation has no significant difference in the passing rate of IMRT plan verification(P＞0.05),which meets the clinical requirements of dose verification.

Reconstruction of thoracic CT based on single-view projection with a cycle dual-task network in radiotherapy / 中华放射肿瘤学杂志

Objective:To construct a cycle dual-task network based on cycleGAN to implement 3D CT synthesis from single-view projection for adaptive radiotherapy of thoracic tumor and then evaluate image quality and dose accuracy.Methods:A total of 45 thoracic tumor patients admitted to the Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University were collected, and 991 cases were also selected from public dataset as pretrained dataset. Multi-view projections were acquired by ASTRA algorithm. The public dataset was divided into a training set of 800 cases, a validation set of 160 cases and a test set of 31 cases. The dataset obtained from patients in our hospital was divided into a training set of 40 cases and a test set of 5 cases. The network included synthetic CT model and multi-view projection prediction model and achieved the dual-task training. The final test only used the synthetic CT model to acquire the predicted CT images and deliver image quality [mean absolute error (MAE), peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM)] and dose evaluation.Results:Image quality evaluation metrics for synthetic CT showed high image synthesis accuracy with MAE of 0.05±0.01, PSNR of 19.08±1.69, SSIM of 0.75±0.04, respectively. The dose distribution calculated on synthetic CT was also close to the actual dose distribution. The mean 3%/3 mm γ pass rate for synthetic CT was 93.1%.Conclusions:A dual-task cycle network modified on cycleGAN has been implemented to rapidly and accurately predict 3D CT from single-view projection, which can be applied to the workflow of adaptive radiotherapy for thoracic cancer. Both image generation quality and dosimetric evaluation demonstrate that synthetic CT can meet the clinical requirements for radiotherapy.

Research on con-beam CT images segmentation method / 中华放射医学与防护杂志

Image-guided radiation therapy (IGRT) is a visual image-guided radiotherapy technique that has many advantages such as increasing the dose of tumor target area and reducing the dose of normal organ exposure. Cone beam CT (CBCT) is one of the most commonly used medical images in IGRT, and the rapid and accurate targeting of CBCT and the segmentation of dangerous organs are of great significance for radiotherapy. The current research method mainly includes partitioning method based on registration and segmentation method based on deep learning. This study reviews the CBCT image segmentation method, existing problems and development directions.

Development and application of three-dimensional point cloud radiotherapy real-time monitoring system based on depth camera / 中华放射肿瘤学杂志

Objective:To develop the real-time radiotherapy monitoring system of three-dimensional (3D) point cloud by using depth camera and verify its feasibility.Methods:Taking the depth camera coordinate system as the world coordinate system, the conversion relationship between the simulation CT coordinate system and the world coordinate system was obtained from the calibration module. The patient's simulation CT point cloud was transformed into the world coordinate system through the above relationship, and registered with the patient's surface point cloud obtained in real-time manner by the depth camera to calculate the six-dimensional (6D) error, and complete the positioning verification and fractional internal position error monitoring in radiotherapy. Mean and standard deviation of 6D calculation error, Hausdorff distance of point cloud after registration and the running time of each part of the program were calculated to verify the feasibility of the system. Fifteen real patients were selected to calculate the 6D error between the system and cone beam CT (CBCT).Results:In the phantom experiment, the errors of the system in the x, y and z axes were (1.292±0.880)mm, (1.963±1.115)mm, (1.496±1.045)mm, respectively, and the errors in the rotation, pitch and roll directions were 0.201°±0.181°, 0.286°±0.326°, 0.181°±0.192°, respectively. For real patients, the translational error of the system was within 2.6 mm, the rotational error was approximately 1°, and the program run at 1-2 frames/s. The precision and speed met the radiotherapy requirement. Conclusion:The 3D point cloud radiotherapy real-time monitoring system based on depth camera can automatically complete the positioning verification before radiotherapy, real-time monitoring of body position during radiotherapy, and provide error visual feedback, which has potential clinical application value.

Magnetic bead-based adsorption strategy for exosome isolation.

Exosomes, one type of extracellular vesicle (EV) secreted by cells, participate in intercellular communication and other biological processes as carriers of lipids, functional proteins, mRNAs, miRNAs, lncRNAs, and DNA fragments. Their presence in biofluids makes them attractive candidates as innovative clinical diagnostic tools. However, the conventional isolation and analysis of high-purity exosomes in clinical application is challenging, with traditional methods facing a number of shortcomings, including low yield or purity, long periods of processing, high cost, and difficulties in standardization. In this study, we provide an overview of commonly used exosome isolation approaches with a focus on magnetic bead-based capture, an ideal methodology with high purity and integrality of exosomes. The current challenges on exosome isolation methods are also described to highlight areas for future research and development.

Functional characterization of piggyBac-like elements from Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

PiggyBac is a transposable DNA element originally discovered in the cabbage looper moth (Trichoplusia ni). The T. ni piggyBac transposon can introduce exogenous fragments into a genome, constructing a transgenic organism. Nevertheless, the comprehensive analysis of endogenous piggyBac-like elements (PLEs) is important before using piggyBac, because they may influence the genetic stability of transgenic lines. Herein, we conducted a genome-wide analysis of PLEs in the brown planthopper (BPH) Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), and identified a total of 28 PLE sequences. All N. lugens piggyBac-like elements (NlPLEs) were present as multiple copies in the genome of BPH. Among the identified NlPLEs, NlPLE25 had the highest copy number and it was distributed on five chromosomes. The full length of NlPLE25 consisted of terminal inverted repeats and sub-terminal inverted repeats at both terminals, as well as a single open reading frame transposase encoding 546 amino acids. Furthermore, NlPLE25 transposase caused precise excision and transposition in cultured insect cells and also restored the original TTAA target sequence after excision. A cross-recognition between the NlPLE25 transposon and the piggyBac transposon was also revealed in this study. These findings provide useful information for the construction of transgenic insect lines.

Dosimetric effect of CT truncated regionson radiotherapy for thoracic esophageal cancer / 中国辐射卫生

@#<b>Objective</b> To investigate the dosimetric effect of truncated regions in computed tomography (CT) images on the targets and organs at risk in volumetric modulated arc therapy (VMAT) for middle thoracic esophageal cancer. <b>Methods</b> CT images of 15 patients with middle thoracic esophageal cancer were selected. Circle masks were used to make the volume of the truncated region account for 10%, 20%, 30%, and 40% of the arm volume, and the corresponding truncated CT images were obtained. The real CT was denoted as CT0. Two radiotherapy plans were made on CT0. One plan was VMAT_1F with full arcs, and the other one was VMAT_3F with arm avoidance. The plans were transplanted to four truncated CT, respectively, and the dosimetric differences between different plans were compared using Wilcoxon signed-rank test. <b>Results</b> Compared with VMAT_1F in CT0, <i>D</i>_mean and <i>V</i>₅ of the lung decreased in VMAT_3F, but <i>D</i>_max of the spinal cord, <i>D</i>_mean of the heart, and <i>V</i>₂₀ of the lung increased. In VMAT_3F, there was no statistically significant difference between the dosimetric parameters in the four truncated CT and those in CT0 (all <i>P</i> > 0.05). In VMAT_1F, except for homogeneity index and <i>D</i>_max of the spinal cord, the dosimetric parameters in four truncated CT were significantly different from those in CT0 (<i>P</i> < 0.05). The dosimetric difference increased with the increase in truncated region-to-volume ratio. <b>Conclusion</b> Complete CT data should be collected in clinical practice, and the radiation field avoiding the truncated regionshould be set if necessary to reduce the influence of the truncated region on dosimetry.

Research progress of MR imaging for prediction of CT imaging / 中国辐射卫生

Medical images can provide clinicans with accurate and comprehensive patients’ information. Morphological or functional abnormalities caused by various diseases can be manifested in many aspects. Although MR images and CT images can highlight the medical image data of different tissue structures of patients, single MR images or CT images cannot fully reflect the complexity of diseases. Using MR image to predict CT image is one of the cross-modal prediction of medical images. In this paper, the methods of MR image prediction for CTmage are classified into four categoriesincluding registration based on atlas, based on image segmentationmethod, based on learning method and based on deep learning method. In our research, we concluded that the method based on deep learning should bemore promoted in the future by compering the existing problems and future development of MR image predicting CT image method.

Development and clinical application of 3D visualization-guided patient positioning system for radiotherapy / 中华放射医学与防护杂志

Objective:To develop a 3D visualization technology-assisted patient positioning system for radiotherapy and compare it with traditional patient positioning method for breast and pelvic radiotherapy.Methods:A total of 40 patients receiving radiotherapy in Changzhou No.2 People′s Hospital from June 2020 to April 2021 were selected for this study, including 20 patients with breast cancer and 20 patients with pelvic cancer.3D visualization reconstruction was carried out using the CT data of the patients for positioning. Then the 3D visualization models were integrated with the real treatment environment and were then shifted to the isocentral positions of accelerators through interactive operations. Based on this, the patients were actually positioned. Every week, all of the patients were firstly treated with traditional positioning, followed by 3D visualization-guided positioning. As a result, 240 times of positioning data of all patients were collected in three weeks. They were compared with the data of cone-beam CT(CBCT)-guided positioning, which served as the gold standard.Results:The absolute positioning errors of 3D visualization-guided positioning along x, y and z axes were (1.92±1.23), (2.04±1.16), and (1.77±1.37)mm, respectively for patients with breast cancer and were (2.07±1.08), (1.33±0.88), and (1.99±1.25)mm, respectively for patients with pelvic cancer. Compared with traditional positioning method , the accuracy of 3D visualization-guided positioning along x、 y, and z axes was increased by 38.83%, 52.40% and 33%, respectively for patients with breast cancer and was improved by 36.84%, 54.04% and 52.58% for patients with pelvic cancer, with all differences being statistically significant along y and z axes ( t=2.956-5.734, P< 0.05). Meanwhile, the error distribution of the two positioning method was statistically significant along in y axis for patients with breast cancer( χ2=7.481, P<0.05) and was statistically significant along each axis for patients with pelvic cancer( χ2=5.900, 6.415, 7.200, P<0.05). Conclusions:The positioning method guided by 3D visualization technology can effectively improve the positioning accuracy of patients with breast cancer and patients with pelvic cancer and is of value in potential clinical application.

Application of MRI segmentation in tumor radiotherapy / 中华放射肿瘤学杂志

Magnetic resonance imaging (MRI) is a technology with no radiation and high resolution of soft tissues. Therefore, MRI-guided radiotherapy has become a hot spot in the field of radiotherapy. It is of great importance to accurately delineate the targets in radiation oncology. Currently, the delineation of targets is mostly completed by manual segmentation, which is time-consuming, subjective and inconsistent. Automatic segmentation can improve the efficiency and consistency without sacrificing the accuracy of segmentation. In this article, the automatic segmentation methods of MRI applied in radiotherapy were reviewed. The goals, challenges and methods of automatic segmentation for different radiotherapy sites including prostate, nasopharyngeal carcinoma, brain tumors and other organs were analyzed and discussed.

Study of volume resolution of prostate motion target by four-dimensional ultrasound / 中华放射肿瘤学杂志

Objective:To explore the volume resolution of prostate motion target by four-dimensional (4D) ultrasound.Methods:The prostate ultrasound model was selected, and the group comparison study was conducted using 4D ultrasound to outline the prostate target under different motion amplitudes (A) and motion period (T). The simulated A value was set as 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm, respectively. The T value was set as 1 s, 2 s, 3 s, and 4 s, respectively. The volume of the target of the model prostate was calculated, and the static ultrasound image of the target was used as the control group to analyze the difference between two groups.Results:When the model was still, the size of the target of ultrasound was consistent with that of CT scan ( P>0.05). When the A values were 0.5 mm and 1 mm, there was no statistical difference between the volume in period 1-4 s and the volume in the target at rest (all P>0.05). When the A values were 2 mm and 3 mm, and the T values were 1 s, 2 s and 3 s there was statistical difference between the volume of target and that of of static ultrasonic target (all P<0.05). When the A value was 2 mm and the T value was 4 s, there was no statistical difference between the target volume and the static target volume ( P=0.710). The range within the group was 6.7 cm 3, and the standard deviation was 1.15 cm 3. When the A value was 3 mm and the T value was 4 s, the volume repeatability of the target was poor, and the range within the group was 14.4 cm 3; when the A values were 4 mm and 5 mm, and the T values were 1-4 s, the range within the group was 3.27-17.63 cm 3 and 6.51-21.02 cm 3, respectively. The volume repeatability of the target under each period was extremely poor, which could not meet the clinical requirements. Conclusion:4D ultrasound can provide reliable reference data for patients′ target delineation within 1-4 s of motion cycle and within 1 mm of motion amplitude, which exerts on effect upon the original position of probe.

Effects of FSEER on immunosuppressive and bone-marrow-suppressive mice after chemotherapy / 中国免疫学杂志

Objective:To observe the effect of FSEER on the immunosuppressive and bone-marrow-suppressive mice after chemotherapy,and explore the mechanism of hematopoietic and immunologic function in mice accentuated by FSEER.Methods: Mice were injected cyclophosphamide(Cy)except control group,then randomly divided into mode group(saline),FSEER groups[120,60 mg/( kg· d) ].The spleen index( SI) of all mice was calculated respectively.Flow cytometry instrument testing mice peripheral blood lymphocytes CD3,CD4,CD8 change.The content of TNF-α,IL-2 and IL-12 in mice serum were measured by ELISA kits.Morphological images of bone marrow of the mice were observed under the microscope after Wright-Giemsa′s staining.Results:The spleen index( SI) was increased in both of the two FSEER groups.ELISA analyses showed that the content of TNF-αand IL-2 was increased in both of the two FSEER groups.The population of CD3+CD4+T lymphocyte and the ratio of CD4+/CD8+were all increased in the low dose experimental group.After treated with FSEER, the hematopoietic depression was improved significantly.Conclusion: FSEER can improve the state of immunosuppressive and myelosuppressive mice caused by Cy thus could alleviate the side effect of chemotherapy ef-fectively.

Expression of apelin-APJ in chronic obstructive pulmonary disease and its significance / 实用医学杂志

Objective To detect the expression of apelin and angiotensin I receptor related protein (APJ) in rats with chronic obstructive pulmonary disease (COPD), and to explore the role of apelin-APJ system in the occurrence and development of COPD. Methods A rat model of COPD was established using the method of smoke exposure. SD rats were randomly divided into a control group and a COPD group. The rats in COPD group were exposed to secondhand cigarette smoke in a fume box twice a day for 4 months. Expressions of apelin mRNA and APJ mRNA in rat lung tissues were detected by real-time quantitative polymerase chain reaction (qRT-PCR). Expressions of apelin protein and APJ protein were determined by immunohistochemistry. Results The expressions of apelin mRNA and APJ mRNA in COPD group were decreased by 44% and 13% as compared with those in the control group. The mRNA expressions of apelin and APJ in rat lung tissues were negatively correlated with RV/(LV + S) (r = -0.454 and -0.448, P < 0.05), and positively related with FEV0.3/FVC (r = 0.529 and 0.475;P < 0.05). Apelin and APJ were mainly expressed in the epithelial cells of the bronch and lung, alveolar macrophages, vascular endothelial cells, and the membrane and cytoplasm of some alveolar wall cells. The expression of apelin and APJ protein was lower in COPD group than in the control group (P < 0.05). Conclusions The mRNA and protein expressions of apelin and APJ are decreased in the lung tissues in rats with COPD , which may be an important factor leading to the development of COPD. Apelin-APJ system might be a new target for prevention and treatment of pulmonary hypertension and right ventricular hypertrophy induced by COPD.

Analysis of diagnosis and treatment on asymptomatic adrenal pheochromocytoma of 33 cases / 中国医师进修杂志

Objective To improve the diagnosis and treatment of asymptomatic adrenal pheochromocytoma. Method The clinical data of 33 patients with asymptomatic adrenal pheochromocytoma were reviewed. Results All the patients were not preut with typical signs and symptoms of pheochromocytoma, 16 patients were found adrenal mass by routine physical examination, 15 patients presented with superior abdominal or flank pain, 1 patient was fever and 1 patient was diarrhea. Most of patients were prent with round mass with low density in the center of the tumor,5 patients had elevated level of plasma epinephrine and norepinephrine (16% ,5/31),24 hours urine CA and VMA were elevated in 6 patients (24%, 6/25) and 5 patients (20%, 5/25) respectively, 26 patients who were suspected pheochromocytoma preoperatively were treated with α-adrenergic blockade (prazosin) to control the blood pressure or with intravenous colloid fluids and blood transfusion to expand intravascular volume before operation. The tumors were removed successfully in 32 patients, and biopsy was done in 1 patient because of the serious invasion to the vena cava by the tumor. All the patients were diagnosed pheochromocytoma histopathologically,and followed up for 1 month to 7 years, no tumor recurrence. Conclusions The patients with asymptomatic adrenal pheochromocytoma have lower catecholamine excretion in their plasma and urine. Combination of modem imaging examinations are useful methods to diagnose asymptomatic adrenal pheochromocytoma. To lower the risk of operation, the control of blood pressure and the expanding of intravascular volume are important for the patients with huge adrenal mass or typical suspected appearance of pheochromocytoma.