Dosimetric and workflow evaluation of first commercial synthetic CT software for clinical use in pelvis
Dosimetric and workflow evaluation of first commercial synthetic CT software for clinical use in pelvis
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DOI：
10.1088/1361-6560/aa5452
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发表时间：
2017-04-21
影响因子：
3.5
通讯作者：
Hunt, Margie
中科院分区：
文献类型：
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作者：
Tyagi, Neelam;Fontenla, Sandra;Hunt, Margie
评价商用合成CT （syn-CT）软件在前列腺放射治疗中的应用。25例前列腺患者在3T磁共振扫描仪上进行治疗位CT和MR模拟扫描。采用市售MR方案，包括用于软组织对比的T2w涡轮自旋回波序列和用于生成同步ct的双回波3D mDIXON快速场回波（FFE）序列。双回声3D FFE B0图用于患者诱导的敏感性失真分析，并评估新的3D平衡FFE序列，用于识别植入的黄金基准标记物和随后的放射治疗过程中的图像引导。组织分为空气、脂肪、水、骨小梁/海绵状骨和致密/皮质骨，并分配了总体HU值。通过将结构和方案从计划CT转移到同步CT并重新计算剂量，分析了同步CT对治疗计划的准确性。通过比较kV x线片与sync -CT生成的数字重建x线片（DRRs）或计划CT生成的传统DRRs的配准，评估治疗机上定位的准确性。同样，使用CBCT和syn-CT的设置精度与使用计划CT的设置精度进行比较。最后，建立了单核磁共振模拟工作流程，并对5例单核磁共振模拟患者进行了端到端测试。所有结构的原始CT和同步CT方案之间的剂量学比较平均在0.5%以内。在syn-CT上的de-novo优化方案满足靶结构和正常结构的机构临床目标。基于B-0图谱的患者诱导的敏感性扭曲在体内和前列腺分别在1 mm和0.5 mm以内。基于mr定位基准的DRR和CBCT定位显示标准偏差< 1mm。端到端测试和MR仿真工作流程得到了成功的验证。MRI衍生的合成CT可以成功地用于前列腺放射治疗的仅磁共振计划和治疗。
To evaluate a commercial synthetic CT (syn-CT) software for use in prostate radiotherapy.Twenty-five prostate patients underwent CT and MR simulation scans in treatment position on a 3T MR scanner. A commercially available MR protocol was used that included a T2w turbo spin-echo sequence for softtissue contrast and a dual echo 3D mDIXON fast field echo (FFE) sequence for generating syn-CT. A dual-echo 3D FFE B0 map was used for patient-induced susceptibility distortion analysis and a new 3D balanced-FFE sequence was evaluated for identification of implanted gold fiducial markers and subsequent image-guidance during radiotherapy delivery. Tissues were classified as air, adipose, water, trabecular/spongy bone and compact/cortical bone and assigned bulk HU values. The accuracy of syn-CT for treatment planning was analyzed by transferring the structures and plan from planning CT to syn-CT and recalculating the dose. Accuracy of localization at the treatment machine was evaluated by comparing registration of kV radiographs to either digitally reconstructed radiographs (DRRs) generated from syn-CT or traditional DRRs generated from the planning CT. Similarly, accuracy of setup using CBCT and syn-CT was compared to that using the planning CT. Finally, a MR-only simulation workflow was established and end-to-end testing was completed on five patients undergoing MR-only simulation.Dosimetric comparison between the original CT and syn-CT plans was within 0.5% on average for all structures. The de-novo optimized plans on the syn-CT met institutional clinical objectives for target and normal structures. Patient-induced susceptibility distortion based on B-0 maps was within 1 mm and 0.5 mm in the body and prostate respectively. DRR and CBCT localization based on MR-localized fiducials showed a standard deviation of < 1 mm. Endto- end testing and MR simulation workflow was successfully validated.MRI derived synthetic CT can be successfully used for a MR-only planning and treatment for prostate radiotherapy.