[Analysis of the complete genome characterization of 11 human astrovirus strains in Shandong Province].

Objective: To study the complete genome characterization of Human Astrovirus (HAstV) in Shandong Province. Methods: Stool samples from acute flaccid paralysis (AFP) surveillance in Shandong Province from 2020 to 2022 were collected, and HAstV nucleic acid was examined by real-time quantitative PCR (qPCR). Next-generation sequencing (NGS) was conducted for the positive samples to obtain complete genome sequences and identify the genotype. Homology comparison and phylogenetic analysis were performed by using BioEdit and Mega software. Results: A total of 667 samples were examined by qPCR, of which 14 were HAstV-positive (2.1%), including HAstV-1 (n=6), MLB1 (n=6), MLB2 (n=1), and VA2 (n=1). The complete genome sequences were obtained from 11 samples. The six HAstV-1 sequences of this study had 98.2% to 99.9% nt similarities with each other and 87.6% to 98.6% with those from other regions. The four MLB1 sequences of this study had 99.1% to 99.9% nt similarities with each other and 92.2% to 99.4% with those from other regions. The VA2 sequence of this study had 96.0% to 96.3% nt similarities with those from other regions. Phylogenetic analysis based on ORF2 region showed that the local HAstV-1 sequences were most closely related to Japanese strains, and had distinct topology with phylogenies based on ORF1a and ORF1b regions. Conclusion: The complete genome sequences of 11 HAstV strains are obtained, and the VA2 complete genome is found.

Setup error of electronic portal image device in IMRT for thoracic tumors and its influence.

OBJECTIVE: The aim of this study was to analyze the setup error of the electronics portal image device (EPID) in intensity-modulated radiation therapy (IMRT) for thoracic tumors and the influence on the outward expansion distance of the target area. PATIENTS AND METHODS: A total of 202 patients with chest tumors admitted to our hospital from March 2016 to March 2018 were selected as the observation subjects. All patients were treated with IMRT. The original plan was developed based on the SM90 obtained by the planning target volume (PTV) expansion method, and the new plan was obtained by shifting the isocenter coordinates of the treatment plan according to the positioning error value obtained by EPID. Before the treatment, EPID scans were performed. The electronic radiation field images (ERIs) were registered with the digitally reconstructed radiographic images (DRRs) generated by the treatment planning system using the image registration software, and the setup errors in the X, Y, and Z directions were further measured. The PTV was developed according to ERIs, and the setup error was simulated to obtain the PTV with 95% internal target volume (ITV) reaching the prescribed dose under the condition of a setup error. The outward expansion distance of clinical target volume (CTV) → PTV was calculated. RESULTS: In this experiment, the setup errors in X, Y, and Z directions were (-2.00±1.16) mm, (0.16±1.14) mm, and (-0.55±1.16) mm, respectively. The systematic error in the Z direction was -3.00 mm, and the random error in the X direction was 3.30 mm. The CTV → PTV outward expansion distance was set as 7, 8 and 7 mm in the X direction, Y direction and Z direction, respectively. At this time, under the presence of setup error, the PTV D95 and the ITV V100 in the new plan were (62.23±3.85) Gy and (97.51±1.56) %, respectively, effectively ensuring that 95% ITV of 90% patients reached the prescribed dose. In contrast, the ITV D95 and ITV V100 in the presence of setup error were (56.11±5.26) Gy and (90.15±3.12) %, respectively, at a CTV → PTV outward expansion distance of 5 mm, which could not guarantee that 95% ITV of 90% patients reached the prescribed dose. In the presence of a setup error, the double-lung 5 Gy irradiation of the total heart volume (V5), the double-lung 20 Gy irradiation of the total heart volume (V20), mean lung dose (MLD), mean heart dose (MHD), and D1 cm3 of the new plan increased by 0.89%, 0.29%, 0.13%, 0.06%, and 5 Gy, respectively, compared with the original plan. CONCLUSIONS: In general, the first treatment of radiotherapy in thoracic tumors mostly has a certain degree of setup error, which is most evident in the X direction. When the CTV → PTV outward expansion distance is set at 7, 8, and 7 mm in the X direction, Y direction, and Z direction, respectively, it can effectively ensure that 95% ITV reach the prescribed dose in 90% of patients in the presence of a setup error. EPID helps to achieve the desired effect of radiotherapy, improves the efficacy of radiotherapy, and reduces the side effects caused by radiotherapy errors.