Department of Radiation Oncology, Cancer Center, Helsinki University Central Hospital, Finland; Department of Physics, University of Helsinki, Finland; Medical Imaging and Radiation Therapy, Kymenlaakso Central Hospital, Kymenlaakso Social and Health Services (Carea), Kotka, Finland.
Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, Finland.
Radiother Oncol. 2017 Dec;125(3):411-419. doi: 10.1016/j.radonc.2017.10.011. Epub 2017 Oct 30.
Recent studies have shown that it is possible to conduct entire radiotherapy treatment planning (RTP) workflow using only MR images. This study aims to develop a generalized intensity-based method to generate synthetic CT (sCT) images from standard T2-weighted (T2) MR images of the pelvis.
This study developed a generalized dual model HU conversion method to convert standard T2 MR image intensity values to synthetic HU values, separately inside and outside of atlas-segmented bone volume contour. The method was developed and evaluated with 20 and 35 prostate cancer patients, respectively. MR images with scanning sequences in clinical use were acquired with four different MR scanners of three vendors.
For the generated synthetic CT (sCT) images of the 35 prostate patients, the mean (and maximal) HU differences in soft and bony tissue volumes were 16 ± 6 HUs (34 HUs) and -46 ± 56 HUs (181 HUs), respectively, against the true CT images. The average of the PTV mean dose difference in sCTs compared to those in true CTs was -0.6 ± 0.4% (-1.3%).
The study provides a generalized method for sCT creation from standard T2 images of the pelvis. The method produced clinically acceptable dose calculation results for all the included scanners and MR sequences.
最近的研究表明，仅使用磁共振（MR）图像即可完成整个放射治疗计划（RTP）流程。本研究旨在开发一种基于强度的通用方法，从骨盆标准 T2 加权（T2）MR 图像生成合成 CT（sCT）图像。
本研究开发了一种通用的双模型 HU 转换方法，将标准 T2 MR 图像强度值分别转换为图谱分割骨体积轮廓内和外的合成 HU 值。该方法分别在 20 例和 35 例前列腺癌患者中进行了开发和评估。使用来自三个供应商的四台不同的 MR 扫描仪采集了具有临床使用扫描序列的 MR 图像。
对于 35 例前列腺患者的生成的合成 CT（sCT）图像，软组织和骨组织体积的平均（和最大）HU 差异分别为 16±6 HU（34 HU）和-46±56 HU（181 HU），与真实 CT 图像相比。与真实 CT 相比，sCT 中 PTV 平均剂量差异的平均值为-0.6±0.4%（-1.3%）。
本研究提供了一种从骨盆标准 T2 图像生成 sCT 的通用方法。该方法针对所有纳入的扫描仪和 MR 序列，生成了可接受的剂量计算结果。
