Purpose: To prospectively analyze the inter-fractional motion of the prostate in patients with prostate cancer treated with intensity-modulated radiation therapy (IMRT) using image-guided radiotherapy (IGRT) with dail...Purpose: To prospectively analyze the inter-fractional motion of the prostate in patients with prostate cancer treated with intensity-modulated radiation therapy (IMRT) using image-guided radiotherapy (IGRT) with daily cone-beam computed tomography (CBCT) as part of a rescan protocol for large offset, and to evaluate the efficacy of our protocol. Materials and Methods: Eligible patients were treated with the following protocol: 1) magnesium oxide and dimethylpolysiloxane were administered to ensure that patients had regular bowel movements;2) the patients were instructed to have an appropriately distended bladder during the planning CT and daily irradiation;3) the daily CBCT image was fused with the planning CT image using the prostate outline;and 4) if large offset was recognized, a rescan CBCT image was obtained after appropriate countermeasures, such as the discharge of gas and defecation, and re-registration was performed. Three shifts for the inter-fractional motion of the prostate were analyzed, in the fractions which needed the CBCT rescan;the displacement data after the final rescan were used. Results: Sixty-one patients were eligible, and a total of 2302 fractions were available for the analysis. Rescans of the CBCT for large offset were performed in 113 (5%) of the 2302 fractions. After the first rescan, the large offset was resolved in 106 (94%) of the 113 fractions. Excessive rectal gas was the reason for the large offset in 94 (83%) of the 113 fractions. The total mean and standard deviation of the inter-fractional motion of the prostate in the AP, LR, and SI directions were 1.1 ± 2.4, -0.1 ± 2.3, and 0.7 ± 3.0 mm, respectively. Conclusion: Large offset was recognized in 5% of all fractions. Daily CBCT with our rescan protocol could resolve the large offset, which was mainly caused by excessive rectal gas, and it may therefore be promising to reduce the inter-fractional motion of the prostate.展开更多
Facial imaging is used to study the facial shapeand its developmental changes over time.This isimportant to diagnose acquired malformations,to studynormal and abnormal growth and to differentiatebetween the results of...Facial imaging is used to study the facial shapeand its developmental changes over time.This isimportant to diagnose acquired malformations,to studynormal and abnormal growth and to differentiatebetween the results of treatment and normal growth,and to validate facial recognition.The two mainmethods to study and record facial imaging are bymeans of cephalometry and anthropometry[1].Cephalometrics is the scientific study of themeasurements of the展开更多
Image-guided radiotherapy(IGRT) provides precise positioning for the tumor target, but it may bring extra irradiation dose in the target positioning with a cone beam CT(CBCT) which has been increasingly used in IGRT. ...Image-guided radiotherapy(IGRT) provides precise positioning for the tumor target, but it may bring extra irradiation dose in the target positioning with a cone beam CT(CBCT) which has been increasingly used in IGRT. In this work, we focused on biological effects of the low-dose irradiation in IGRT, which have not been considered so far. Primary human fibroblasts cells from the lung and MRC-5 were irradiated by a CBCT. DNA doublestrand breaks(c-H2 AX foci) and micronucleus frequency of the irradiated samples were analyzed. Compared to the control, the c-H2 AX foci yields of the samples irradiated to 16 m Gy increased significantly, and the micronuclei rate of the samples irradiated for 3 days increased notably. The dose by imaging guidance device can be genotoxic to normal tissue cells, suggesting a potential risk of a secondary cancer. The effects, if confirmed by clinical studies,should be considered prudentially in designing IGRT treatment plans for the radiosensitive population, especially for children.展开更多
The main goal of this study was to introduce a novel three-dimensional procedure to objectively quantify both inner and outer condylar remodelling on preoperative multi-slice computed tomography （MSCT） and postopera...The main goal of this study was to introduce a novel three-dimensional procedure to objectively quantify both inner and outer condylar remodelling on preoperative multi-slice computed tomography （MSCT） and postoperative cone-beam computed tomography （CBCT） images. Second, the reliability and accuracy of this condylar volume quantification method was assessed. The mandibles of 20 patients （11 female and 9 male） who underwent bimaxillary surgery were semi-automatically extracted from MSCT/CBCT scans and rendered in 3D. The resulting condyles were spatially matched by using an anatomical landmark-based registration procedure. A standardized sphere was created around each condyle, and the condylar bone volume within this selected region of interest was automatically calculated. To investigate the reproducibility of the method, inter- and intra-observer reliability was calculated for assessments made by two experienced radiologists twice five months apart in a set of ten randomly selected patients. To test the accuracy of the bone segmentation, the inner and outer bone structures of one dry mandible, scanned according to the clinical set-up, were compared with the gold standard, micro-CT. Thirty-eight condyles showed a significant （P〈O.05） mean bone volume decrease of 26.4%_ 11.4% （502.9 mm3＋ 268.1 mm3）. No significant effects of side, sex or age were found. Good to excellent （ICC〉 0.6） intra- and inter-observer reliability was observed for both MSCT and CBCT. Moreover, the bone segmentation accuracy was less than one voxel （0.4 mm） for MSCT （0.3 mm __. 0.2 mm） and CBCT （0.4 mm _ 0.3 mm）, thus indicating the clinical potential of this method for objective follow-up in pathological condylar resorption.展开更多
Cone-beam computed tornography （CBCT） has the notable features of high efficiency and high precision, and is widely used in areas such as medical imaging and industrial non-destructive testing. However, the presence...Cone-beam computed tornography （CBCT） has the notable features of high efficiency and high precision, and is widely used in areas such as medical imaging and industrial non-destructive testing. However, the presence of the ray scatter reduces the quality of CT images. By referencing the slit collimation approach, a scatter correction method for CBCT based on the interlacing-slit scan is proposed. Firstly, according to the characteristics of CBCT imaging, a scatter suppression plate with interlacing slits is designed and fabricated. Then the imaging of the scatter suppression plate is analyzed, and a scatter correction Calculation method for CBCT based on the image fusion is proposed, which can splice out a complete set of scatter suppression projection images according to the interlacing-slit projection images of the left and the right imaging regions in the scatter suppression plate, and simultaneously complete the scatter correction within the fiat panel detector （FPD）. Finally, the overall process of scatter suppression and correction is provided. The experimental results show that this method can significantly improve the clarity of the slice images and achieve a good scatter correction.展开更多
This study describes a case of antral septum with alveolar process extension that is identified using cone-beam computed tomography (CBCT). Periapical radiolucency was observed in the maxillary sinus, and clinical and...This study describes a case of antral septum with alveolar process extension that is identified using cone-beam computed tomography (CBCT). Periapical radiolucency was observed in the maxillary sinus, and clinical and radiographic examinations ruled out the possibility of odontogenic lesions. CBCT was performed to elucidate the radiolucency identified using periapical radiography. A 3-D image indicated that the maxillary sinus extended into the alveolar process toward the palatal cortical bone in the region of the maxillary right first molar, as well as an antral septum extending from the inferior and lateral wall of the right maxillary sinus. CBCT is an important tool for use in dental practice because CBCT images reveal the entire volume of the maxillary sinus and allow for identification of patient anatomy and anatomical variations, which is essential for planning appropriate surgical interventions.展开更多
文摘Purpose: To prospectively analyze the inter-fractional motion of the prostate in patients with prostate cancer treated with intensity-modulated radiation therapy (IMRT) using image-guided radiotherapy (IGRT) with daily cone-beam computed tomography (CBCT) as part of a rescan protocol for large offset, and to evaluate the efficacy of our protocol. Materials and Methods: Eligible patients were treated with the following protocol: 1) magnesium oxide and dimethylpolysiloxane were administered to ensure that patients had regular bowel movements;2) the patients were instructed to have an appropriately distended bladder during the planning CT and daily irradiation;3) the daily CBCT image was fused with the planning CT image using the prostate outline;and 4) if large offset was recognized, a rescan CBCT image was obtained after appropriate countermeasures, such as the discharge of gas and defecation, and re-registration was performed. Three shifts for the inter-fractional motion of the prostate were analyzed, in the fractions which needed the CBCT rescan;the displacement data after the final rescan were used. Results: Sixty-one patients were eligible, and a total of 2302 fractions were available for the analysis. Rescans of the CBCT for large offset were performed in 113 (5%) of the 2302 fractions. After the first rescan, the large offset was resolved in 106 (94%) of the 113 fractions. Excessive rectal gas was the reason for the large offset in 94 (83%) of the 113 fractions. The total mean and standard deviation of the inter-fractional motion of the prostate in the AP, LR, and SI directions were 1.1 ± 2.4, -0.1 ± 2.3, and 0.7 ± 3.0 mm, respectively. Conclusion: Large offset was recognized in 5% of all fractions. Daily CBCT with our rescan protocol could resolve the large offset, which was mainly caused by excessive rectal gas, and it may therefore be promising to reduce the inter-fractional motion of the prostate.
文摘Facial imaging is used to study the facial shapeand its developmental changes over time.This isimportant to diagnose acquired malformations,to studynormal and abnormal growth and to differentiatebetween the results of treatment and normal growth,and to validate facial recognition.The two mainmethods to study and record facial imaging are bymeans of cephalometry and anthropometry[1].Cephalometrics is the scientific study of themeasurements of the
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA03040000)the National Natural Science Foundation under Grant No.30900386+1 种基金the Anhui Provincial Natural Science Foundation under Grant Nos.090413095 and 11040606Q55the National Natural Science Foundation of Department of Education of Anhui Province under Grant No KJ2010B380
文摘Image-guided radiotherapy(IGRT) provides precise positioning for the tumor target, but it may bring extra irradiation dose in the target positioning with a cone beam CT(CBCT) which has been increasingly used in IGRT. In this work, we focused on biological effects of the low-dose irradiation in IGRT, which have not been considered so far. Primary human fibroblasts cells from the lung and MRC-5 were irradiated by a CBCT. DNA doublestrand breaks(c-H2 AX foci) and micronucleus frequency of the irradiated samples were analyzed. Compared to the control, the c-H2 AX foci yields of the samples irradiated to 16 m Gy increased significantly, and the micronuclei rate of the samples irradiated for 3 days increased notably. The dose by imaging guidance device can be genotoxic to normal tissue cells, suggesting a potential risk of a secondary cancer. The effects, if confirmed by clinical studies,should be considered prudentially in designing IGRT treatment plans for the radiosensitive population, especially for children.
基金the Coordination for the Improvement of Higher Education Personnel(CAPES)programmeScience without borders from Brazilian governmentthe Research Foundation Flanders(FWO)from Flemish government for the fellowship support
文摘The main goal of this study was to introduce a novel three-dimensional procedure to objectively quantify both inner and outer condylar remodelling on preoperative multi-slice computed tomography （MSCT） and postoperative cone-beam computed tomography （CBCT） images. Second, the reliability and accuracy of this condylar volume quantification method was assessed. The mandibles of 20 patients （11 female and 9 male） who underwent bimaxillary surgery were semi-automatically extracted from MSCT/CBCT scans and rendered in 3D. The resulting condyles were spatially matched by using an anatomical landmark-based registration procedure. A standardized sphere was created around each condyle, and the condylar bone volume within this selected region of interest was automatically calculated. To investigate the reproducibility of the method, inter- and intra-observer reliability was calculated for assessments made by two experienced radiologists twice five months apart in a set of ten randomly selected patients. To test the accuracy of the bone segmentation, the inner and outer bone structures of one dry mandible, scanned according to the clinical set-up, were compared with the gold standard, micro-CT. Thirty-eight condyles showed a significant （P〈O.05） mean bone volume decrease of 26.4%_ 11.4% （502.9 mm3＋ 268.1 mm3）. No significant effects of side, sex or age were found. Good to excellent （ICC〉 0.6） intra- and inter-observer reliability was observed for both MSCT and CBCT. Moreover, the bone segmentation accuracy was less than one voxel （0.4 mm） for MSCT （0.3 mm __. 0.2 mm） and CBCT （0.4 mm _ 0.3 mm）, thus indicating the clinical potential of this method for objective follow-up in pathological condylar resorption.
基金supported by the National Science and Technology Major Project of the Ministry of Industry and Information Technology of China(Grant No.2012ZX04007021)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.51105315)+1 种基金the Natural Science Basic Research Program of Shaanxi Province,China(Grant No.2013JM7003)the Northwestern Polytechnical University Foundation for Fundamental Research,China(Grant Nos.3102014KYJD022 and JC20120226)
文摘Cone-beam computed tornography （CBCT） has the notable features of high efficiency and high precision, and is widely used in areas such as medical imaging and industrial non-destructive testing. However, the presence of the ray scatter reduces the quality of CT images. By referencing the slit collimation approach, a scatter correction method for CBCT based on the interlacing-slit scan is proposed. Firstly, according to the characteristics of CBCT imaging, a scatter suppression plate with interlacing slits is designed and fabricated. Then the imaging of the scatter suppression plate is analyzed, and a scatter correction Calculation method for CBCT based on the image fusion is proposed, which can splice out a complete set of scatter suppression projection images according to the interlacing-slit projection images of the left and the right imaging regions in the scatter suppression plate, and simultaneously complete the scatter correction within the fiat panel detector （FPD）. Finally, the overall process of scatter suppression and correction is provided. The experimental results show that this method can significantly improve the clarity of the slice images and achieve a good scatter correction.
文摘目的:主观评价和客观评估不同成像参数下CBCT的图像质量,分析图像质量的主观评价和客观评价间的关系。方法:分别采用6台不同品牌CBCT扫描仪〔3D Accuitomo(Morita)、i-CAT(Kavo)、5G(NewTom)、Smart3D(北京朗视)、DCT Pro(Vatech)、VGi(NewTom)〕,在各个品牌的典型曝光条件下(电压和电流强度不同)扫描空间分辨率模体和高仿真头模,7位医师对拍摄的CBCT图像进行主观评价打分,比较不同CBCT扫描仪的空间分辨率和对常见口腔解剖结构的可见性。客观评价指标采用各仪器所获的图像空间分辩率(LP/mm)。结果:7位医师的组内一致性和组间一致性均无显著性差异。主观评价New Tom 5G为2分,i-CAT为5分,其余4个品牌匀为4分,客观评价i-CAT的LP/mm为1.8,Smart3D为2.0,其余4个品牌为1.0~1.7。在相同管电流条件下,不同管电压的图像主观质量有显著性差异。在相同管电压条件下,不同管电流的图像主观质量有显著性差异。结论:图像质量的主客观评价具有一定的一致性,不同品牌之间的客观评价差异可能与电压、电流强度不同有关。
文摘目的探究鼻咽癌患者调强放射治疗(IMRT)中应用锥形束计算机断层扫描(CBCT)和机载影像系统(on Board Image,OBI)分析对摆位误差的影响。方法筛选2018年7月~2021年7月桂林医学院附属医院接诊的140例鼻咽癌患者进行分组对照研究,所有患者均依据数字表法随机分为CBCT组和OBI组,每组各70例患者。比较两组的摆位误差及放射剂量差异,分析CBCT、OBI系统在降低鼻咽癌患者IMRT的摆位误差中的价值。结果(1)相比于校正前,校正后两组的摆位误差均明显降低,并且相比于OBI组,校正后CBCT组的摆位误差明显更低(P均<0.05);(2)在降低鼻咽癌患者IMRT的摆位误差中,CBCT的ROC曲线下面积(area under curve,AUC)、特异度、敏感度与OBI对比均明显升高(Z=2.241,P<0.000);(3)相比于校正前,校正后两组的计划靶区边界(margins of planning target volume,MPTV)值均明显降低,并且相比于OBI组,校正后CBCT组的MPTV值明显更低(P均<0.05);(4)两组脑干、脊髓、晶状体和视交叉的实际剂量高于计划剂量,且CBCT组低于OBI组,差异有统计学意义(P<0.05)。结论鼻咽癌患者应用CBCT、OBI系统分析均可校正摆位误差,提高患者的摆位与调强放疗精确度。CBCT、OBI系统可以通过减少摆位误差,有可能进一步缩小计划靶区范围,从而减少靶区临近危机器官的照射剂量的临床目的。CBCT的作用更明显,是值得临床推广应用的方案。
文摘This study describes a case of antral septum with alveolar process extension that is identified using cone-beam computed tomography (CBCT). Periapical radiolucency was observed in the maxillary sinus, and clinical and radiographic examinations ruled out the possibility of odontogenic lesions. CBCT was performed to elucidate the radiolucency identified using periapical radiography. A 3-D image indicated that the maxillary sinus extended into the alveolar process toward the palatal cortical bone in the region of the maxillary right first molar, as well as an antral septum extending from the inferior and lateral wall of the right maxillary sinus. CBCT is an important tool for use in dental practice because CBCT images reveal the entire volume of the maxillary sinus and allow for identification of patient anatomy and anatomical variations, which is essential for planning appropriate surgical interventions.
