乳腺癌放疗摆位误差分析及其对心肺受量的影响

发布时间：2019-02-28 21:17

【摘要】：目的：通过模拟摆位误差,探讨乳腺癌放疗中摆位误差对心肺受量的影响。方法：通过移动射野中心,模拟三个方向(X、Y、Z轴)的线性摆位误差,模拟的误差值分别选取为2、3、5、7、9mm,将射野中心向患侧乳腺方向移动2mm,重新计算心肺受量,并将新剂量序列记为X2,将治疗中心向健侧乳腺方向移动2mm,将新剂量序列记为X-2,模拟其他误差值时新剂量序列分别记为X3、X-3、X5、X-5等。将射野中心向头侧方向移动2mm,重新计算靶区及危及器官剂量,并将新剂量序列记为Y2,将射野中心向脚侧方向移动2mm,将新剂量序列记为Y-2,模拟其他误差值时新剂量序列分别记为Y3、Y-3、Y5、Y-5等。将射野中心向前胸方向移动2mm,重新计算靶区及危及器官剂量,并将新剂量序列记为Z2,将治疗中心向后背方向移动2mm,将新剂量序列记为Z-2,模拟其他误差值时新剂量序列分别记为Z3、Z-3、Z5、 Z-5等。结果：①对于肺,Y-5、Y-7、Y-9、Z5、Z7、Z9的双肺V20较原计划增加；X-5、X-7、X-9、Y-5、Y-7、Y-9、Z5、Z7、Z9的患肺V20较原计划增加,均超过限量；X-3、X-5、X-7、X-9、Y-3、Y-5Y-7、Y-9、Z5、 Z7、Z9的患肺平均剂量较原计划增加4.39%、7.65%、11.55%、17.15%、7.5%、12.5%、17.8%、23.1%、8.0%、11.48%、10.7%。②对于心脏,X-3、X-5、X-7、X-9、Y-5、Y-7、Y-9的V30较原计划增加,其中X-7、X-9、Y-9超过限量；X-7、X-9的V40较原计划增加；X-5、X-7、X-9、Y-5、Y-7、Y-9的心脏平均剂量较原计划增加；增加幅度为51cGy、79cGy、107cGy、 85cGy、125cGy、171cGy。结论：①患侧方向、头方向、后背方向大于5mm的误差会使患肺V20超过限量；患侧肺方向、头方向大于3mm,后背方向大于5mm的误差会使患侧肺平均剂量产生较大增加。②患侧方向、头方向大于5mm的误差会使心脏平均剂量产生较大增加。③建议当患侧方向、头方向、后背方向误差大于5mm时,应校正误差；当预估患者产生放射性肺损伤风险较大时,患侧方向、头方向校正阈值为3mm。目的：利用千伏级锥形束CT(CBCT)分析头肩体垫固定的乳腺癌患者放疗摆位中的误差,并为临床靶区(CTV)外扩为计划靶区(PTV)提供依据。方法：利用CBCT分析头肩体垫固定的乳腺癌病人放疗摆位中的误差,获得患者左右(X)、头脚(Y)、上下(Z)三个轴方向的线性误差(X、Y、Z),及绕此三个轴的旋转误差(Xr、Yr、Zr)。统计误差数据,评价头肩体垫的优劣,并由公式MPTV=2.5Σ+0.7δ，，计算出CTV外扩为PTV的范围(MPTV)。结果：53例患者共得到265次摆位误差的数据。对于线性摆位误差,三个方向总系统误差为2.5mm、 2.3mm、1.9mm,总随机误差为2.5mm、2.2mm、2.2mm。建议外扩边界为8.0mm,7.3mm、6.3mm。对于旋转误差,绕三轴方向的总系统误差分别为1.03。、1.1。、0.95。,总随机误差为0.79。、1.15。、0.72。。结论：头肩体垫具有较好的摆位精度。利用CBCT测量乳腺癌放疗的摆位误差,为乳腺癌放疗CTV外扩为PTV提供参考依据,提高了乳腺癌放疗的精准性。
[Abstract]:Objective: to investigate the effect of placement error on cardio-pulmonary dose in radiotherapy of breast cancer by simulating positioning error. Methods: the linear positioning errors in three directions (X, Y, Z axis) were simulated by moving the center of the field. The error values were 2, 3, 5, 7, 9 mm, respectively. The center of the field was moved 2 mm to the affected side of the breast, and the cardio-pulmonary dose was recalculated. The new dose sequence was recorded as X2, the treatment center moved 2 mm to the contralateral mammary gland, the new dose sequence was recorded as X ~ (2), and the new dose sequence was recorded as X _ 3, X _ (3), X _ (5), X _ (5) and so on when other error values were simulated. Moving the center of the field 2 mm to the head side, recalculating the target area and endangering organ doses, recording the new dose sequence as Y 2, moving the center of the field 2 mm to the crural side, and recording the new dose sequence as Y\-2\ {# * $} 2. The new dose sequences were recorded as Y _ 3, Y _ 5, Y _ 5 and so on when other error values were simulated. Move the center of the field 2 mm to the front chest, recalculate the target and organ-endangering doses, write the new dose sequence Z2, move the treatment center 2 mm to the back, and write the new dose sequence Z-2. The new dose sequences were recorded as Z _ 3, Z _ 5, Z _ 5 and so on when other errors were simulated. Results: (1) for the lung, V20 of both lungs was higher than that of the original plan for Y5, Y7, Y9, Z5, Z7 and Z9; The lung V20 of X5, X7, X9, Y5, Y7, Y9, Z5, Z7, Z9 were increased compared with the original plan and exceeded the limit. The average lung dose for X-3, X-5, X-7, X-9, Y-3, Y-5Y-7, Y-9, Z5, Z7, Z9 increased by 4.39%, 7.65%, 11.55%, 17.15%, 7.5%, respectively. 12.5%, 17.8%, 23.1%, 8.0%, 11.48%, 10.7% for the heart, X3, X5, X7, X9, Y5, Y7, Y9, V30 is higher than originally planned. Among them, X7, X9, Y9 exceeded the limit; The V40 of X-7, X-9, X-5, X-7, X-9, Y-5, Y-7, Y-9 and Y-9 were increased by 51 cGy, 79 cGy, 107 cGy, 85 cGy, 125 cGy, 171 cGY, and 51 cGy, 79 cGy, 107 cGy, 85 cGy, 125 cGy, 171 cGY, respectively. Conclusion: 1the error of the affected side direction, the head direction and the back direction greater than the 5mm will cause the lung V20 to exceed the limit; The mean lung dose of the affected side increased greatly when the direction of the affected side was greater than 3 mm in the head direction, and the error of the back direction was greater than that of 5mm. (2) in the affected side, The error of head direction greater than 5mm will increase the average dose of heart. 3 it is suggested that when the error of head direction, head direction and back direction is greater than that of 5mm, the error should be corrected. When the risk of radiation-induced lung injury was high, the correction threshold of the affected side and head direction was 3 mm. Aim: to analyze the error of radiotherapy placement in patients with breast cancer fixed with head and shoulder pad by using kVA cone bundle CT (CBCT), and to provide the basis for the expansion of clinical target area (CTV) as the planned target area (PTV). Methods: CBCT was used to analyze the error of radiotherapy placement in patients with breast cancer fixed with head and shoulder pad. The linear errors (X, Y, Z) of the upper and lower (Z) axes of left and right (X), head and foot (Y), were obtained. And the rotation error (Xr,Yr,Zr) around the three axes. Statistical error data are used to evaluate the advantages and disadvantages of the head shoulder pad. Based on the formula MPTV=2.5 危 0.7 未, the range (MPTV). Of the expansion from CTV to PTV is calculated. Results: data of 265 placement errors were obtained in 53 patients. For the linear positioning error, the total system error in three directions is 2.5 mm, 2.3 mm, 1.9 mm, and the total random error is 2.5 mm, 2.2 mm. It is suggested that the outer boundary be 8.0mm, 7.3mm, 6.3mm. For the rotation error, the total system error around the triaxial direction is 1.03,1.1,0.95.The total random error is 0.79,1.15.0.72. Conclusion: the head-shoulder pad has good positioning accuracy. Using CBCT to measure the positioning error of breast cancer radiotherapy can provide reference for the external expansion of breast cancer radiotherapy CTV for PTV, and improve the precision of breast cancer radiotherapy.
【学位授予单位】：广西医科大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R737.9

【参考文献】