Vanquin L, Boydev C, Korhonen J, Rault E, Crop F, Lacornerie T, Wagner A, Laffarguette J, Pasquier D, Reynaert N
Unité de physique médicale, centre Oscar-Lambret, 3, rue Combemale, 59020 Lille, France.
Unité de physique médicale, centre Oscar-Lambret, 3, rue Combemale, 59020 Lille, France; Unité de physique médicale, institut Curie, 35, rue Dailly, 92210 Saint-Cloud, France.
Cancer Radiother. 2019 Jul;23(4):281-289. doi: 10.1016/j.canrad.2018.09.005.
Magnetic resonance imaging (MRI) plays an increasing role in radiotherapy dose planning. Indeed, MRI offers superior soft tissue contrast compared to computerized tomography (CT) and therefore could provide a better delineation of target volumes and organs at risk than CT for radiotherapy. Furthermore, an MRI-only radiotherapy workflow would suppress registration errors inherent to the registration of MRI with CT. However, the estimation of the electronic density of tissues using MRI images is still a challenging issue. The purpose of this work was to design and evaluate a pseudo-CT generation method for prostate cancer treatments.
A pseudo-CT was generated for ten prostate cancer patients using an elastic deformation based method. For each patient, dose delivered to the patient was calculated using both the planning CT and the pseudo-CT. Dose differences between CT and pseudo-CT were investigated.
Mean dose relative difference in the planning target volume is 0.9% on average and ranges from 0.1% to 1.7%. In organs at risks, this value is 1.8%, 0.8%, 0.8% and 1% on average in the rectum, the right and left femoral heads, and the bladder respectively.
The dose calculated using the pseudo-CT is very close to the dose calculated using the CT for both organs at risk and PTV. These results confirm that pseudo-CT images generated using the proposed method could be used to calculate radiotherapy treatment doses on MRI images.
磁共振成像（MRI）在放射治疗剂量规划中发挥着越来越重要的作用。事实上，与计算机断层扫描（CT）相比，MRI具有更好的软组织对比度，因此在放射治疗中，它能够比CT更清晰地勾勒靶区体积和危及器官。此外，仅使用MRI的放射治疗流程将消除MRI与CT配准中固有的配准误差。然而，利用MRI图像估计组织的电子密度仍然是一个具有挑战性的问题。这项工作的目的是设计并评估一种用于前列腺癌治疗的伪CT生成方法。
使用基于弹性变形的方法为10例前列腺癌患者生成伪CT。对于每位患者，分别使用计划CT和伪CT计算其接受的剂量。研究CT与伪CT之间的剂量差异。
计划靶区内平均剂量相对差异平均为0.9%，范围在0.1%至1.7%之间。在危及器官中，直肠、左右股骨头和膀胱的平均剂量相对差异分别为1.8%、0.8%、0.8%和1%。
对于危及器官和计划靶区，使用伪CT计算的剂量与使用CT计算的剂量非常接近。这些结果证实，使用所提出的方法生成的伪CT图像可用于在MRI图像上计算放射治疗剂量。
