肿瘤变化和危及器官状态对宫颈癌放疗剂量的影响

发布时间：2018-06-22 10:28

本文选题：宫颈癌 + 螺旋断层放疗　；参考：《南方医科大学》2017年硕士论文

【摘要】：目的分析宫颈癌放疗中肿瘤变化及膀胱、直肠充盈状态等诸因素对靶区和危及器官(OAR)实际剂量的影响,为临床提供帮助。方法选取2013年9月至2015年6月于陆军总医院(原北京军区总医院)行螺旋断层放疗(Tomotherapy)宫颈癌患者20例。患者仰卧位,热塑体膜固定后于CT模拟定位机下定位,将定位图像传至Pinnacle 9.2系统,分别勾画肿瘤(GTV)、临床靶区(CTV)、计划靶区(PTV)以及OAR,再将勾画后的CT图像传至Tomotherapy治疗计划系统4.1.2.2进行计划设计。计划完成并验证通过后开始放疗。每次治疗前均行兆伏级CT(MVCT)扫描,并将MVCT重建后与定位的千伏级CT(KVCT)图像进行自动、手动配准,以校正摆位误差。选取每5次放疗中的第1、3次MVCT图像与定位时的KVCT图像,在Tomotherapy自适应模块中重新计算剂量分布,得到对应单次实际受照射剂量。将对应的融合CT图像以及单次剂量分布传输至形变软件(MIM 6.5)中进行剂量叠加,得到总受照射剂量。在每5次的第1、3次MVCT图像上,参考初始计划的靶区,以相同的原则重新勾画靶区和OAR,观察分次照射间靶区与OAR体积、位置变化分别对靶区、OAR实际剂量的影响;将各分次的MVCT及靶区、总受照射剂量叠加成的计划称为Plan-2,初始计划称为Plan-1,在DVH上比较Plan-1和Plan-2靶区、OAR剂量分布情况。采用SPSS20.0软件进行数据处理。结果1靶区1.1肿瘤变化对靶区位置的影响1.1.1 GTV体积与照射剂量的关系随照射剂量增加,肿瘤体积逐渐缩小,以10～40 Gy缩小显著,平均每10 Gy缩小10%以上,40 Gy后退缩速度减缓(表1)。1.1.2 GTV中心位置与照射剂量的关系随照射剂量增加,肿瘤体积缩小,GTV中心位置也发生相应变化,但变化范围不大。10～40 Gy照射肿瘤缩小最明显时的平均位置变化是0.55～0.56 cm,其中前后方向位移中位值为0.38 cm,头脚方向为0.27 cm,左右方向为0.22 cm。均无统计学意义(P0.05)(表2)。1.1.3子宫中心位置与照射剂量的关系照射剂量10Gy后,子宫前后和头脚方向的中心位置变化逐渐增大,在前后方向位移中位值为0.55 cm,头脚方向为0.60 cm(P=0.000,0.077),左右方向变化不明显为0.22cm(P=0.564)(表3)。1.1.4 CTV中心位置与照射剂量的关系在治疗过程中,CTV中心位置变化与照射剂量无关(表4)。1.2位置变化对靶区剂量的影响Plan-2中GTV和子宫的D98及D2与Plan-1相比均无差异,Dmean分别高于Plan-1 1.45%和 1.60%(P=0.002,0.002),D95分别高于 Plan-1 1.48%和 1.34%(P=0.058,0.073);CTVD95、Dmean及D2与 Plan-1相比均无差异,D98、V95%低于 Plan-1,降低比例分别为 7.69%、2.59%(P=0.002,0.001)(表 5)。95%处方剂量覆盖CTV体积为97.36%±1.85%,中位漏照百分比2.01%(0.46～5.99%),中位漏照体积为18.67cm3(2.52～45.77cm3),漏照部位主要位于子宫前部及髂总淋巴引流区上部(图a,b)。1.3 OAR充盈状态对靶区的影响1.3.1膀胱充盈状态对CTV中心位置的影响膀胱体积与计划体积相差≤300 cm3或体积相差之比≤40%时,对CTV中心位置影响不大;但当膀胱体积与计划体积相差300 cm3或体积相差之比40%时,CTV的前后、头脚方向位移较大(P=0.034,0.032或0.013,0.001),但对左右方向无明显影响(表6)。1.3.2膀胱充盈状态对CTV剂量的影响当膀胱体积与计划体积相差300 cm3或体积相差之比40%时,CTV Dmin明显降低(P=0.004,0.000),但对CTV Dmax、Dmean无明显影响(P0.05)(表7)。1.3.3直肠充盈状态对CTV中心位置的影响直肠体积差异绝对值及其差异比对CTV中心位置影响未显示出统计学差异(P0.05)(表 8)。1.3.4直肠充盈状态对CTV剂量的影响直肠体积差异绝对值及其差异比对CTV的Dmax、Dmean及Dmin影响均未显示出统计学差异(P0.05)(表9)。2 OAR2.1肿瘤变化对OAR中心位置和剂量的影响2.1.1肿瘤变化对膀胱中心位置和剂量的影响随照射剂量增加,肿瘤缩小,对膀胱的中心位置无明显影响(表10);但治疗过程中,膀胱的V45、V50分别较计划的Plan-1降低了 21.16%、33.02%(P=0.035,0.004),而 V30、V40、Dmean无显著差异(P0.05)(表 11)。2.1.2肿瘤变化对直肠中心位置和剂量的影响随照射剂量增加,肿瘤体积缩小,直肠中心位置无明显变化(表12);但Plan-2 较计划的 Plan-1,直肠 V50、Dmean分别增高 48.48%、20.25%(P=0.049,0.000),而 V30、V40、V45 则无显著差异(P0.05)(表 13)。2.2 OAR充盈状态对膀胱和直肠受照剂量的影响2.2.1膀胱2.2.1.1分次治疗中膀胱的充盈状态在分次治疗中膀胱的充盈状态差异很大,与照射剂量无明显关系(表14)。2.2.1.2膀胱充盈状态对膀胱受照剂量的影响膀胱体积差异绝对值及差异比对膀胱Dmax、Dmin、Dmean、V30、V40、V45及V50影响未见明显规律(P0.05)(表15)。2.2.2直肠2.2.2.1分次治疗中直肠的充盈状态在治疗过程中直肠的充盈状态普遍较前增大,与照射剂量无明显关系(表16)。2.2.2.2直肠充盈状态对直肠受照剂量的影响直肠体积差异绝对值及差异比对直肠Dmin、Dmax、Dmean影响无明显差异(P0.05),但直肠体积差异大于30cm3时使其V30、V40、V45、V50增大,或直肠体积差异比大于30%时使其V40、V45、V50增大(P0.05)(表17)。结论1、宫颈癌Tomotherapy调强放疗中,随肿瘤缩小,子宫位置有不同程度的变化,引起靶区剂量变化,主要表现为子宫前倾造成部分靶区漏照,但漏照体积较小。在图像引导下,CTV外扩5 mm可以满足靶区剂量要求。2、膀胱的充盈变化在300 cm3或40%以内时,对靶区的剂量影响不大,所以放疗期间不必苛求病人严格的憋尿,适度充盈即可。3、直肠的充盈状态对靶区剂量无明显影响,但当直肠体积变化30 cm3或30%时使直肠受照剂量明显增加,建议治疗前排空直肠,减少损伤的发生。
[Abstract]:Objective to analyze the effects of tumor changes, bladder, filling state and other factors on the actual dose of target area and endanger organ (OAR) in the radiotherapy of cervical cancer. Methods 20 cases of cervical cancer were selected from September 2013 to June 2015 in Army General Hospital (General Hospital of Beijing Military Region). Patients with cervical cancer were treated with spiral fault radiotherapy (Tomotherapy). In the supine position, the thermoplastic film was fixed under the CT positioning machine. The location image was passed to the Pinnacle 9.2 system. The tumor (GTV), the clinical target area (CTV), the planned target area (PTV) and the OAR, and then the outlined CT images were passed to the Tomotherapy treatment plan system 4.1.2.2 to be planned. After the completion and verification, the radiotherapy was completed and the radiotherapy started after the radiotherapy. The memevolt CT (MVCT) scan is performed before each treatment, and the mv level CT (KVCT) image of the MVCT is reconstructed automatically to correct the pendulum position error. The 1,3 time MVCT image and the positioning KVCT image in every 5 radiotherapy are selected and the dose distribution is recalculated in the Tomotherapy self adaptation module, and the corresponding single practice is obtained. The corresponding fusion CT image and the single dose distribution were transferred to the deformation software (MIM 6.5) for dose superposition, and the total irradiated dose was obtained. On every 5 1,3 MVCT images, the target area and OAR were redrawn with the same principle as the same principle. The volume of the target area between the fractional irradiation and the OAR volume was observed, and the position change was observed. The effect on the target area and the actual dose of OAR respectively; the plan to superimpose the total irradiated doses of each sub MVCT and target area is called Plan-2, the initial plan is called Plan-1, the target area of Plan-1 and Plan-2 is compared with the DVH, the distribution of OAR dose is compared with the SPSS20.0 software. Results the effect of the 1.1 tumor change on the target area in the 1 target area is 1.. 1.1 the relationship between the volume of 1.1 and the dose of radiation increased with the dose of irradiation, the volume of the tumor gradually narrowed, the decrease of the volume of the tumor was 10~40 Gy, the average of each 10 Gy was reduced by more than 10%, and the rate of contraction was slowed down after 40 Gy (Table 1) the relationship between the center position of.1.1.2 and the dose of radiation increased with the dose of irradiation, the volume of the tumor was reduced, and the location of the GTV center also changed correspondingly. The changes in the range of.10 to 40 Gy irradiated tumor were 0.55 to 0.56 cm, which was 0.38 cm, the head and foot direction was 0.27 cm, and the left and right direction was 0.22 cm. (P0.05) (P0.05) (Table 2) the relationship between the center of the uterus and the dose of irradiation, after the dose 10Gy, before the uterus, the uterus was in front of the uterus. The change of the center position of the post and head direction is gradually increased, the position value of the front and back displacement is 0.55 cm, the head and foot is 0.60 cm (P=0.000,0.077). The change of the left and right direction is not obviously 0.22cm (P=0.564) (P=0.564) (Table 3).1.1.4 CTV center position and the irradiation dose. The change of CTV center position is independent of the irradiation dose (Table 4).1.2 during the treatment process. The effect of position change on target area dose in Plan-2, GTV and D98 and D2 of uterus were no difference compared with Plan-1, Dmean was higher than Plan-1 1.45% and 1.60% (P=0.002,0.002), D95 higher than Plan-1 1.48% and 1.34% (P=0.058,0.073), respectively. 2.59% (P=0.002,0.001) (Table 5) (Table 5).95% prescription dose coverage CTV volume 97.36% + 1.85%, median leakage percentage 2.01% (0.46 to 5.99%), median leakage volume of 18.67cm3 (2.52 to 45.77cm3), leakage location is mainly located in the front of the uterus and the upper iliac lymphatic drainage area (a, B).1.3 OAR filling state of the target area of the target area of the bladder filling state When the difference of bladder volume and planned volume is less than 300 cm3 or the ratio of volume difference is less than 40%, the position of the CTV center has little effect on the position of CTV center, but when the difference between the volume of the bladder and the planned volume is 300 cm3 or the ratio of volume to volume is 40%, the head and foot direction is larger (P =0.034,0.032 or 0.013,0.001) before and after CTV, but it is not clear to the left and right direction. Effect (Table 6) the effect of.1.3.2 bladder filling state on the dose of CTV, when the difference of bladder volume and planned volume was 300 cm3 or volume ratio 40%, CTV Dmin decreased significantly (P=0.004,0.000), but CTV Dmax, Dmean had no obvious effect (P0.05) (P0.05) (7).1.3.3 rectum filling state affecting the absolute value of the rectal volume difference in the location of the CTV center and the absolute value of the rectal volume difference and The effect of difference ratio on the location of CTV center did not show significant difference (P0.05) (Table 8) the effect of.1.3.4 rectal filling state on the dose of the rectum on the dose of CTV, the difference of the absolute value of the rectal volume difference and its difference was not statistically significant (P0.05) (P0.05) (P0.05) (P0.05) (P0.05) (P0.05) (P0.05) (P0.05) (Table 9) the effect of the change of.2 OAR2.1 on the location and dose of the OAR Center The effect of tumor changes on the central position and dose of the bladder increased with the dose of irradiation, and the tumor was reduced, and the central position of the bladder was not significantly affected (table 10). But during the treatment, the V45 and V50 of the bladder decreased by 21.16%, 33.02% (P=0.035,0.004), respectively, while V30, V40, and Dmean were not significantly different (Table 11).2.1.2 tumor changes The effect of the rectal center position and dose increased with the dose of irradiation, the tumor volume reduced and the rectal center position was not significantly changed (Table 12), but Plan-2 was 48.48%, 20.25% (P=0.049,0.000), respectively, compared with planned Plan-1, rectal V50 and Dmean, while V30, V40, V45 were not significantly different (table 13).2.2 OAR filling state of the bladder and rectum The effect of dose on the filling state of bladder in 2.2.1 2.2.1.1 fractionated bladder is very different during the fractionated treatment, and there is no significant relationship with the dose of irradiation (table 14) the absolute and difference ratio of bladder volume in the bladder filling state of the bladder affects the bladder volume difference and difference ratio in bladder Dmax, Dmin, Dmean, V30, V40, V45, and V50 shadows. No obvious regularity (P0.05) (table 15) (table 15).2.2.2 rectal filling state during the rectal 2.2.2.1 fractionation in the treatment process, the filling state of rectum was generally higher in the treatment process, and there was no significant relationship with the dose of irradiation (table 16) the effect of rectal volume difference on rectal volume difference absolute value and difference ratio on rectal Dmin, Dmax, Dmean had no significant difference (P0.05), but when the volume difference of rectum was greater than that of 30cm3, its V30, V40, V45, V50 increased, or the volume difference of the rectum was greater than 30% (P0.05) (P0.05) (Table 17). Conclusion 1, in the intensive radiation radiotherapy of cervical cancer, the uterine position changes with different degrees, leading to the change in the dose of the target area. The leakage of some target area was caused by the exversion of the uterus, but the volume of the leakage was small. Under the guidance of the image, CTV expanded 5 mm to meet the target dose.2. When the filling of the bladder was within 300 cm3 or 40%, the dose had little influence on the target area. The condition has no obvious effect on the dose of the target area, but when the volume of the rectum changes 30 cm3 or 30%, the dose of the rectum is obviously increased. It is suggested that the rectum be emptied before treatment to reduce the injury.
【学位授予单位】：南方医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R737.33

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