目的 分析比较锥形束CT(CBCT)与MOSAIQ两系统用于测量胸部放射治疗(放疗)摆位误差情况。 方法 2011年2月－9月,随机选择21例用热塑模固定的胸部调强治疗患者，进行同次摆位的CBCT图像采集和电子射野影像(EPID)正侧位图像采集。将CBCT图像与定位CT图像进行匹配，图像经iViewGT系统传输至MOSAIQ系统图像处理模块中与计划生成的数字重建图像(DRR)正侧位片进行匹配，分别记录两套系统图像匹配结果在X(左右)方向、Y(头脚)方向、Z(前后)方向的平移误差及CBCT的旋转误差值，计算其均值、标准差，进行统计学处理。 结果 本研究共获取图像106组，每组内包含一次CBCT图像和EPID图像。CBCT和MOSAIQ系统下EPID匹配结果平移误差在X、Y、Z方向分别为(−0.103 ± 0.240)cm、(−0.086 ± 0.342)cm、(0.017 ± 0184)cm和(0.005 ± 0.214)cm、(−0.004 ± 0.0.315)cm、(−0.113 ± 0.239)cm；旋转误差在X、Y、Z方向分别为(0.792 ± 1.173)°、(−0.130 ± 1.407)°、(0.793 ± 0.960)°，其中≤3°的概率分别为98.2%、97.2%、99.1%，最大绝对值分别为5°、3.4°、3.3°。两套系统在X、Y、Z三个方向的平移误差经配对样本检验，在Y方向P＞0.05，在X和Z方向上P值均＜0.05， 两系统的测量差值有直线负相关关系。 结论 CBCT和EPID在测量胸部放疗靶区中心的平移误差中差异有统计学意义，因此建议在做胸部放疗时有CBCT的情况下应优先使用。
ObjectiveTo compare the dosimetric differences among flattening filter free intensity modulated radiotherapy (3FIMRT), flattening filter free volumetric modulated arc therapy (3FVMAT), filter free intensity modulated radiotherapy (IMRT), and filter free volumetric modulated arc therapy (VMAT) for hyperthyroidism exophthalmus patients.MethodsComputed tomography (CT) scans of 29 patients, who were diagnosed with hyperthyroidism exophthalmus and treated with radiation therapy between September 2016 and September 2017, were selected for study. Four treatment plans with the same dose prescription and objective constrains were designed for each patient based on their images, consisting of IMRT, VMAT, 3FIMRT, and 3FVMAT. The target dosimetric distribution, normal tissue radiation dose, monitor units, and treatment time of each plan were evaluated.ResultsFour types of plans were all able to satisfy the clinical treatment requirements, and there were no significant differences in maximum dose, mean dose (Dmean), homogeneity index of the targets (P>0.05). For the parameters minimum dose, V50%, conformity index (CI), gradient index of the targets, statistically significant differences were observed among the four kinds of technologies (F=10.920, 35.860, 11.320, 17.790; P<0.05). The CI of IMRT and 3FIMRT were superior to those of VMAT and 3FVMAT, but there was no significant difference between IMRT and 3FIMRT. In terms of Lens Dmean and Brain Dmean, statistically significant differences were observed among the four kinds of technologies (F=5.054, 83.780; P<0.05). For Lens Dmean and Brain Dmean, 3FVMAT achieved better sparing effects when compared with the other three plans. The total monitor units and treatment time did not significantly differ between 3FVMAT and VMAT. The mean monitor units of 3FVMAT were 65.07% and 70.22% less than that of IMRT and 3FIMRT respectively. The mean treatment time of 3FVMAT were 48.1% and 35.24% less than that of IMRT and 3FIMRT respectively.Conclusion3FVMAT can bring more dosimetric advantages for hyperthyroidism exophthalmus radiation therapy when compared with IMRT, 3FIMRT, and VMAT.
ObjectiveTo investigate the clinical feasibility of optical surface imaging (OSI) system in guiding thermoplastic body film to fix radiotherapy of pelvic tumors.MethodsFrom January to May in 2019, 20 pelvic tumor patients fixed with thermoplastic films were selected. After the first treatment, cone beam CT (CBCT) was performed to verify and correct the setup errors. OSI was used to collect the patient’s image information as the reference image for the later treatment setup. The later treatment was performed by traditional three-point setup, and OSI was used to record the setup data and monitor the treatment. CBCT scan results were taken as the standard, to calculate the system error (Σ), random error (σ) and margin of three-point and OSI setup. The result of CBCT scan was defined as three-point setup error.ResultsIn lateral-medial, superior-inferior, and anterior-posterior directions, the OSI system errors were 0.14, 0.37, and 0.14 cm, respectively, the random errors were 0.20, 0.57, and 0.23 cm, respectively, and the corresponding margins were 0.49, 1.32, and 0.51 cm, respectively; the three-point setup system errors were 0.13, 0.39, and 0.12 cm, respectively, the random errors were 0.15, 0.43, and 0.13 cm, respectively, and the corresponding margins were 0.43, 1.28, and 0.39 cm, respectively. If the target coverage rate was counted at the 0.8 cm outward margin, the proportions of the three-point setup in lateral-medial, superior-inferior and anterior-posterior were 100.00%, 80.65%, and 100.00%, respectively, and those of the OSI setup were 100.00%, 95.48%, and 99.35%, respectively. Pearson analysis showed that the weakly correlation of lateral-medial, superior-inferior directions had statistical significance (P<0.05), and there was no statistical significance in the other directions (P>0.05).ConclusionsCompared with the traditional three-point setup, OSI cannot improve the setup precision of thermoplastic body film fixation in pelvic tumor radiotherapy. OSI acquired the image of thermoplastic phantom, which is quite different from the actual target location of the patient. OSI application method should be improved in clinical application.
【摘要】 目的 利用不同匹配区域对锥形束CT（CBCT）与定位CT（FBCT）分别配准，测量出鼻咽癌放射治疗中颈部的变形误差。 方法 分析2007年4月-2008年12月收治鼻咽癌患者23例，调整治疗床前198次CBCT扫描。将鼻咽部扫描CBCT图像匹配区域分为上下两个区域进行对比分析。其中上匹配区域为:上界为蝶窦上缘，下界为颈4下缘，侧界包括下颌骨外轮廓，前界为上颌窦1/2，后界为平棘突后缘；下匹配区域为:上界约颈4下缘，下界约胸2-3下缘，侧界包括椎体外轮廓，前界包括皮肤，后界平棘突后缘。匹配方式选择骨，比较匹配结果差异。 结果 选择上与下匹配区域结果除Y（头脚）方向旋转误差无统计学差异外，余均有统计学差异（Plt;0.05） 。差值在X（左右）、Z（前后）、Y（头脚）方向平移分别为（1.14±2.80）、（0.47±1.41）、（0.58±3.88） mm，旋转误差X、Y、Z方向分别为（0.90±1.98）、（0.80±2.03）、（0.68±1.90）°。 结论 鼻咽癌放射治疗中颈部区域存在一定变形误差，通过CBCT引导发现变形误差并进行正确纠正是必须的，结合临床实际及靶区与危及器官的变化为重新计划提供依据。【Abstract】 Objective To investigate the rotation errors due to neck deformation in nasopharyngeal cancer (NPC) radiotherapy with different match areas to register conebeam CT(CBCT) from image guiding and fanbeam (FBCT) from simulation. Methods A total of 198 pre-correction CBCT data sets from 23 NPC patients from April 2007 to December 2008 were retrospectively analyzed. The matching areas in CBCT images were divided into up and down region of interest (ROI). For the up ROI, the superior, inferior, left and right, anterior, and posterior boundary were set parallel with sphenoid sinus up side, C4 down side, mandible outside, and 1/2 of maxillary air sinus and acanthi. For the down ROI, the lines were set parallel with C4 down side, T2-3 down side, neck outside, skin surface and acanthi respectively in all directions. All registrations were performed automatically by bony anatomy and the results were compared. Results The registration results by the up and the down ROI showed significant difference except Y direction for rotation. The translation error was (1.14±2.80),(0.47±1.41),and (0.58±3.88) mm, respectively; and the rotation error was (0.90±1.98),(0.80±2.03),and (0.68±1.90) ° in X, Y, and Z direction, respectively. 〖WTHZ〗Conclusions〖WTBZ〗There are some significant deformation errors at neck areas in NPC radiotherapy. It is important to find out the deformation and correct it with CBCT image guiding. This kind of error information may provide clues for re-planning in addition to clinical practice and the changes of clinical targets and involved organs.
目的 通过非小细胞肺癌（NSCLC）图像引导放射治疗（IGRT）过程中，每次治疗前获取的锥形束CT图像，动态观察肿瘤体积的变化。 方法 2009年2月－2010年8月18例周围型NSCLC患者接受IGRT。每次治疗前进行千伏级锥形束CT（KV-CBCT）图像的采集。每周在KV-CBCT图像上勾画肿瘤靶区并计算靶区体积，经统计后分析肿瘤治疗过程中体积的变化。 结果 治疗开始时平均体积为28.5 cm3（2.5～109.1 cm3），治疗结束时平均体积为17.1 cm3 （1.4～73.4 cm3）。平均退缩率为35.9%（3.9%～68.9%），平均每天的退缩率为1.5% （0.1%～5.4%）。治疗结束时，0例病灶完全消退，1例部分消退，10例微小消退，7例稳定。 结论 治疗过程中，NSCLC肿瘤的退缩可以通过KV-CBCT进行观察。当病灶为周围型时，能对肿瘤体积的变化进行客观有效的评价。放射治疗过程中肿瘤的体积改变具有很大的异质性，肿瘤在治疗过程中体积均有一定的退缩，但治疗结束时大多数病灶仅为微小消退或稳定。