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Objective To investigate the influence of respiratory motion on target dose distribution in radiotherapy for patients with lung tumors. Methods The Big Bore Brilliance CT with bellows system was used to gain the 4DCT sets and respiratory frequency information of the patients. The moving ranges of the tumors in left-right (LR), anterior-posterior (AP) and cranial-caudal (CC) directions were measured from the center coordinate values of gross tumor volume of ten time-phase CT sets in the treatment planning sys-tem. Then a breathing model was used to simulate the tumor motions due to respiration. A 4-dimensional motion table was used to mimic the motion of lung tumor in beams-eye-view (BEV). A 2-dimensional semi-conductor beams measurement system was fixed to the table to measure the 2-dimensional dose distribution of static and dynamic targets using the treatment beams at gantry angle of 0°. Finally, the differences of the dose distribution between the static and moving phantom were compared and analyzed with the statistical soft-ware R. Results When the amplitude (half of the moving rang) in the CC direction was 1 cm, the passing ratio of relative dose difference ≤4% in one beam field was minimal (1.1%), and there was 58% maximal relative dose absence. The 4% passing ratios media in the CC direction were 94.7%, 79.4%, 58.6% and 37.1% in <0.25, 0.25-<0.50, 0.50- <0.75 and ≥0.75 mm amplitude (X<'2>=29.20,P=0.000), but were all similar in the AP and LR directions. The mean value of the relative dose change in the high dose area was smaller than the low dose area in the 89% beam fields. When only the CC direction was consid-ered, the 4% passing ratio of 3.6 s and 8.2 s period was 72% and 60%, respectively. Conclusions The amplitude in the CC direction is a factor impacting the dose distribution of the moving target. The influence of respiratory motion on high dose area is more than that on low dose area. When the other respiratory param-eters are fixed, the motion of long period has more influence on the dose than that of short period. Special at-tention should be paid to the patients with tumor of more than 0.5 cm amplitude in the CC direction when planning the intensity modulated radiotherapy.

6.Effect of polysaccharide sulfate 916 on the production of nitric oxide in ECV304 cells induced by cytokines and H(2)O(2).

Decheng REN ; Meiyu GENG ; Guanhua DU

Chinese Medical Journal 2002;115(4):614-616

7.Significance and mechanism of Tet1 against Mycobacterium marinum infection in mice

Xin WEN ; Jingrui SONG ; Liangjie LUO ; Mei WAN ; Yunfei CHEN ; Shuang ZHOU ; Cairong DING ; Dan LI ; Debing DU ; Decheng WANG

Chinese Journal of Microbiology and Immunology 2021;41(3):165-173

Objective:To investigate the significance and mechanism of ten-eleven translocation (Tet1) against Mycobacterium marinum ( Mm) infection in mice. Methods:SPF wild-type C57BL/6 and Tet1-knockout (Tet1KO) mice were injected intravenously with Mm. All mice were monitored and the abscesses formed in tail were observed and quantified. Pathological changes in mouse tail tissues were observed using hematoxylin and eosin (HE) staining and transmission electron microscopy and the differences between the two groups were analyzed. Immunohistochemistry staining was used to detect the expression and distribution of TNF-α and TGF-β in mouse tail tissues. Moreover, mouse tail tissues were cultured on 7H10 plates for bacterial counting. The expression of NF-κBp65 and TGF-β was detected by Western blot. Results:Obvious lesions including abscesses and ulcers were formed in the Mm-infected C57BL/6, but only scattered small abscesses were observed in Mm-infected Tet1KO mice. During Mm infection, the bacterial load was gradually increased in C57BL/6 mice, but decreased in Tet1KO mice. Histopathological examination showed that obvious inflammatory cell infiltration and typical granulomatous lesions were found in Mm-infected C57BL/6 mice, while no significant inflammatory cell infiltration was detected in Mm-infected Tet1KO mice. Immunohistochemistry staining demonstrated that the expression of TNF-α and TGF-β was lower in Mm-infected Tet1KO mice than in Mm-infected C57BL/6 mice. Moreover, the expression of phosphorylated NF-κBp65 and TGF-β was significantly reduced in Mm-infected Tet1KO mice as compared with that in Mm-infected C57BL/6 mice. Conclusions:Deletion of Tet1 could alleviate the inflammatory damage mediated by Mm and enhance the host immune response to bacteria.