| 屈超,尼加提·阿卜杜热伊木,哈尼克孜·奴尔买买提,张宝忠,张继坤.改良头颈肩热塑体膜固定下乳腺癌改良根治术后调强放疗中的摆位误差分析[J].中华放射医学与防护杂志,2020,40(7):529-535 |
| 改良头颈肩热塑体膜固定下乳腺癌改良根治术后调强放疗中的摆位误差分析 |
| Positioning error analysis of intensity modulated radiation therapy after modified radical mastectomy for breast cancer patients with modified head neck and shoulder thermoplastics mask |
| 投稿时间：2019-11-12 |
| DOI：10.3760/cma.j.issn.0254-5098.2020.07.007 |
| 中文关键词: 乳腺肿瘤/调强放射疗法 体位固定 摆位误差 热塑体膜 锥形束CT |
| 英文关键词:Breast cancer/IMRT Immobilization Setup error Thermoplastic mask Cone-beam CT |
| 基金项目:云南省应用基础研究计划项目-青年项目（2017FD005） |
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| 中文摘要: |
| 目的 应用锥形束CT分析改良头颈肩热塑体膜和乳腺托架在乳腺癌改良根治术后调强放疗中的摆位精度差异。方法 回顾性分析天津医科大学肿瘤医院2015年8月至2018年12月68例接受调强放疗（IMRT）的乳腺癌改良根治术后患者资料。根据体位固定方式的不同，将患者分为改良头颈肩热塑体膜组（体膜组，42例）和乳腺托架组（托架组，26例）。在患者的第1、6、11、16、21次治疗摆位后行锥形束CT（CBCT）扫描，获得两组患者在左右（RL）、腹背（AP）、头脚（SI）方向的摆位误差，同时记录放疗摆位的时间。比较两组的摆位误差、分布比例、摆位时间，计算出各自的MPTV外放值，并分析多种因素对体膜组患者摆位误差的影响。结果 42例体膜组扫描210次，26例托架组扫描130次。体膜组和托架组在RL、AP、SI方向的摆位误差分别为（2.12±2.01）和（2.38±1.92）mm、（3.29±2.46）和（3.88±2.76）mm、（3.47±2.29）和（4.11±3.15）mm，其中两组在AP和SI方向的摆位误差比较，差异均有统计学意义（t=-2.05、-2.16，P<0.05）；SI方向体膜组摆位误差≤ 3 mm的次数占总扫描次数的比例较高，优于托架组差异有统计学意义（χ2=4.97，P<0.05）；当AP和SI方向体膜组摆位误差>5 mm的次数占总扫描次数的比例较低，优于托架组差异有统计学意义（χ2=5.21、9.29，P<0.05）。体膜组的摆位时间较短，优于托架组差异有统计学意义（t=-2.16，P<0.05）。RL、AP、SI方向体膜组计算的MPTV值均小于托架组。改良头颈肩热塑体膜体位固定方式对高龄（≥ 60岁）、体质量指数（BMI）≥ 24 kg/m2和对放疗过程相对不熟悉（治疗时间≤ 2周）的患者会造成AP和（或）SI方向的摆位误差偏大。其中，SI方向<60岁的患者摆位误差较小，优于高龄患者（≥ 60岁）差异有统计学意义（t=-2.43，P<0.05）；AP和SI方向BMI<24 kg/m2的患者摆位误差较小，优于BMI ≥ 24 kg/m2的患者，差异有统计学意义（t=-2.21、-2.04，P<0.05）；AP方向治疗时间>2周的患者摆位误差较小，优于对放疗过程相对不熟悉的患者（治疗时间≤ 2周）差异有统计学意义（t=2.23，P<0.05）。结论 在乳腺癌改良根治术后IMRT放疗时应用改良头颈肩热塑体膜可以降低腹背和头脚方向的摆位误差，同时缩短摆位时间。对于≥ 60岁、BMI ≥ 24 kg/m2和对放疗过程相对不熟悉（治疗时间≤ 2周）的患者，要关注腹背和头脚方向的摆位，以保证放疗的效果。 |
| 英文摘要: |
| Objective To analyze the difference of positioning accuracy by cone beam CT(CBCT) between modified head neck shoulder thermoplastic mask and breast bracket in intensity modulated radiotherapy for breast cancer patients after modified radical mastectomy. Methods A total of 68 cases of breast cancer treated with IMRT after modified radical mastectomy were selected from August 2015 to December 2018. According to the different immobalization methods, the patients were divided into two groups:modified head neck shoulder thermoplastic mask group (body mask group, 42 cases) and breast bracket group (bracket group, 26 cases). After the first, sixth, 11th, 16th and 21st treatment, the patients were scanned by CBCT. The positioning errors in left and right (RL), anterior and posterior (AP) and head and foot (SI) directions were obtained, and the duration of radiotherapy positioning was recorded. The positioning error, distribution ratio and positioning duration were compared between two groups, and the respective MPTV margin were calculated. The influence of various factors on the setup error of patients was analyzed in the mask group. Results There were 210 scans in the body mask group and 130 in the bracket group. The setup errors of the body mask group and bracket group in RL, AP and SI directions were (2.12±2.01) and (2.38±1.92) mm, (3.29±2.46) and (3.88±2.76) mm, (3.47±2.29) and (4.11±3.15) mm, respectively, and the differences in AP and SI directions were statistically significant (t=-2.05, -2.16, P<0.05). The proportion of setup errors less than or equal to 3 mm in the direction for body mask group was higher than that of bracket group (χ2=4.97, P<0.05). The proportion of setup errors more than 5 mm in AP and SI directions for body mask group was lower than that of bracket group (χ2=5.21,9.29, P<0.05). The positioning duration of mask group was shorter than of bracket group (t=-2.16, P<0.05). The MPTV margins of the mask group in RL, AP and SI directions were smaller than those of the bracket group. The modified head, neck and shoulder thermoplastic mask immobalization method led to large setup errors in AP and/or SI directions for the elderly (≥ 60 years old), the patients with body mass index (BMI) ≥ 24 kg/m2 and the patients who were relatively unfamiliar with the radiotherapy process (treatment time ≤ 2 weeks). The setup error for patients aged < 60 years old in SI direction was smaller than that for the elderly (≥ 60 years old) patients (t=-2.43, P<0.05). The setup error for patients with BMI <24 kg/m2 in AP and Si directions was smaller than that with BMI ≥ 24 kg/m2 (t=-2.21, -2.04, P<0.05). The setup error for treatment time > 2 weeks in AP direction was smaller than that for treatment time ≤ 2 weeks (t=2.23, P<0.05). Conclusions In IMRT radiotherapy for breast cancer patients after modified radical mastectomy, the application of modified head neck shoulder thermoplastic mask can reduce the setup error in the anterior-posterior and superior-inferior directions, and shorten the positioning duration. For the elderly (≥ 60 years old), BMI ≥ 24 kg/m2 and the patients who are not familiar with the radiotherapy process (treatment time ≤ 2 weeks), attention should be paid to the setup of anterior-posterior and superior-inferior directions to ensure the treatment effect of radiotherapy. |
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