摘要
目的 通过锥形束CT评估前列腺癌放疗期间膀胱充盈度差异对实际剂量分布变化的影响,为前列腺癌自适应放疗提供参考。方法 选取前列腺癌患者20例,每周进行1次CBCT扫描并在其上勾画靶区和危及器官。以治疗时CBCT与定位时CT的膀胱充盈差异入组,将同一患者的多套CBCT图像分为膀胱欠充盈组(-250~-50mL)和膀胱过充盈组(50~250mL)。将CT计划复制至CBCT上,使用密度覆盖法来计算CBCT计划剂量,并得到相应剂量分布,比较分析不同膀胱充盈情况下的剂量学差异。结果 20例患者共获得140套CBCT图像,膀胱欠充盈组和膀胱过充盈组分别入组40套和42套。CBCT计划剂量与定位CT计划剂量相比,下列剂量学参数差异有统计学意义(P<0.05),膀胱欠充盈组中PTV处分剂量覆盖降低,膀胱和直肠的V60及膀胱的V70增加;膀胱过充盈组中,PTV处方剂量覆盖降低,膀胱的V60有所降低。结论 膀胱充盈差异会导致患者实际靶区覆盖降低,膀胱充盈不足时膀胱和直肠实际剂量会增加,膀胱过充盈时则可根据患者实际情况进行治疗。
Objective To evaluate the clinical requirements and dose distribution of volumetric changes of bladder filling in prostate cancer radiotherapy by cone beam CT(CBCT).Methods A total of 20 patients were included in this study,each patients have 7 sets of CBCT,and the image data sets were contoured and calculated.Take the CT scans’bladder filling as reference(CBCT’s bladder volume-CT’s bladder volume),divided multiple CBCT sets of one patient into low bladder filling group(-250~-50 mL)and high bladder filling group(50~250 mL).The density override approach were used to get the CBCTs’HU and electron density,then copy the CT plan to CBCTs and recalculated CBCT plan to analyze the influence of the bladder filling difference on the target and organ at risk(OAR)’s dose parameters include PTV coverage,CI,HI and OAR’s V70 Gy,V60 Gy etc.Result In total of 20 patients,a total of 140 CBCT image data sets were collected,the low bladder filling group and the high bladder filling group had 40 and 42 CBCT sets,respectively.Compared with CT Plan,the differences of the following parameters were of statistical significance(P<0.05).In the Low group,the prescription dose coverage of PTV were reduced to 95%±3.61%,the V60 and V70 of bladder and rectum had increased by 5.22%±6.37%,5.29%±6.18%,3.01%±4.60%,respectively;In the High group,the prescription dose coverage of PTV were reduced to 96.71%±1.84%,V60 and V50 of bladder had decreased by 5.27(±1.77)%,6.26%(±3.04)%,respectively.Conclusions During treatment of prostate cancer patients,a better control of bladder filling is recommended to avoid the bladder volume difference between CT and CBCT,the inconsistent bladder filling states will cause actual target coverage were decreased,low bladder filling will cause bladder and rectum actual dose were increased,high bladder filling can be treated by patients actual situation.
作者
张天宇
李彩虹
昌志刚
王沛沛
李金凯
孙新臣
ZHANG Tian-yu;LI Cai-hong;CHANG Zhi-gang;WANG Pei-pei;LI Jin-kai;SUN Xin-chen(Nanjing Medical University,Nanjing 211166,Jiangsu Province,China;Department of Radiotherapy,The First Affiliated Hospital with Nanjing Medical University,Nanjing 210029,Jiangsu Province,China)
出处
《中国CT和MRI杂志》
2023年第5期102-104,共3页
Chinese Journal of CT and MRI
