Assessment of setup uncertainty in hypofractionated liver radiation therapy with a breath-hold technique using automatic image registration-based image guidance
Assessment of setup uncertainty in hypofractionated liver radiation therapy with a breath-hold technique using automatic image registration-based image guidance
复制标题
DOI：
10.1186/s13014-019-1361-6
复制
发表时间：
2019-08-30
影响因子：
3.6
通讯作者：
Beddar, Sam
中科院分区：
文献类型：
--
作者：
Choi, Gye Won;Suh, Yelin;Beddar, Sam
背景放射治疗中的目标定位受到许多不确定性来源的影响。尽管采取了尽量减少呼吸运动的措施，但大分割肝脏放射治疗的治疗受到来自非自主器官运动和腹部器官形状和位置每日变化的残余不确定性的进一步挑战。为了解决剩余的不确定性，诊所在不同的软组织对比度水平下实施图像引导的放射治疗。本研究利用了使用室内计算机断层扫描（CT）成像接受大分割肝脏放射治疗的患者的治疗记录，以评估设置不确定性，并在没有室内CT成像的情况下估计适当的计划治疗体积（PTV）边界。方法收集了69例接受大分割放射治疗的患者的917张治疗前每日室内CT图像，采用吸气屏气技术。对于每次治疗，使用CT-CT对准软件，基于肝脏形状自动将每日CT与计划CT初始对准。初始对准后，通过目视检查两个图像确定手动移位校正，并应用校正将患者移位到医生批准的治疗位置。以最终比对为金标准，量化了自动比对中的系统和随机不确定性，并将不确定性用于计算PTV裕度。结果最终和自动对齐之间的中位误差为1.1 mm（0-24.3 mm），38%的治疗片段需要手动校正>= 3 mm。前后（AP）方向的系统不确定度为1.5 mm，左右（LR）方向为1.1 mm，上下（SI）方向为2.4 mm。随机不确定性在AP方向为2.2 mm，在LR方向为1.9 mm，在SI方向为2.2 mm。在没有室内CT成像的情况下，推荐使用的PTV边缘为AP 5.3 mm，LR 3.5 mm，SI方向5.1 mm。结论基于软组织对线的手法移位矫正在腹部手术中具有重要意义。室内CT可以将PTV边缘减少5 mm，这可能对大分割肝脏放射治疗中的剂量递增和正常组织保护特别有益。
Background Target localization in radiation therapy is affected by numerous sources of uncertainty. Despite measures to minimize the breathing motion, the treatment of hypofractionated liver radiation therapy is further challenged by residual uncertainty coming from involuntary organ motion and daily changes in the shape and location of abdominal organs. To address the residual uncertainty, clinics implement image-guided radiation therapy at varying levels of soft-tissue contrast. This study utilized the treatment records from the patients that have received hypofractionated liver radiation therapy using in-room computed tomography (CT) imaging to assess the setup uncertainty and to estimate the appropriate planning treatment volume (PTV) margins in the absence of in-room CT imaging. Methods We collected 917 pre-treatment daily in-room CT images from 69 patients who received hypofractionated radiation therapy to the liver with the inspiration breath-hold technique. For each treatment, the daily CT was initially aligned to the planning CT based on the shape of the liver automatically using a CT-CT alignment software. After the initial alignment, manual shift corrections were determined by visual inspection of the two images, and the corrections were applied to shift the patient to the physician-approved treatment position. Considering the final alignment as the gold-standard setup, systematic and random uncertainties in the automatic alignment were quantified, and the uncertainties were used to calculate the PTV margins. Results The median discrepancy between the final and automatic alignment was 1.1 mm (0-24.3 mm), and 38% of treated fractions required manual corrections of >= 3 mm. The systematic uncertainty was 1.5 mm in the anterior-posterior (AP) direction, 1.1 mm in the left-right (LR) direction, and 2.4 mm in the superior-inferior (SI) direction. The random uncertainty was 2.2 mm in the AP, 1.9 mm in the LR, and 2.2 mm in the SI direction. The PTV margins recommended to be used in the absence of in-room CT imaging were 5.3 mm in the AP, 3.5 mm in the LR, and 5.1 mm in the SI direction. Conclusions Manual shift correction based on soft-tissue alignment is substantial in the treatment of the abdominal region. In-room CT can reduce PTV margin by up to 5 mm, which may be especially beneficial for dose escalation and normal tissue sparing in hypofractionated liver radiation therapy.