Masi Marica, Landoni Valeria, Faiella Adriana, Farneti Alessia, Marzi Simona, Guerrisi Maria, Sanguineti Giuseppe
Department of Medical Physics, IRCSS Regina Elena National Cancer Institute, Rome, Italy; Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy.
Department of Medical Physics, IRCSS Regina Elena National Cancer Institute, Rome, Italy.
Phys Med. 2021 Nov 27;92:32-39. doi: 10.1016/j.ejmp.2021.11.010.
To evaluate the accuracy of rigid coregistration between multiparametric magnetic resonance (mpMR) and computed tomography (CT) images for radiotherapy of prostate bed cancer recurrence.
Fifty-three patients (59 nodules) accrued in a prospective study on salvage radiotherapy for prostatic bed recurrence were suitable for the analysis. Patients underwent a pre radiotherapy mpMR exam and a planning CT in the same treatment position and with control of organ filling. The site of recurrence was delineated on mpMR images and contours transferred on planning CT images using both rigid and deformable registrations. Coregistrations were evaluated by mathematical operators that quantify deformation (Jacobian determinant and vector curl) and similarity indices (Dice and Jaccard coefficients). Dose coverage was evaluated.
Deformable registration did not change volumes, (p = 0.92 MW test). The Jacobian coefficient and the vector curl revealed no important image deformations. Dice and Jaccard coefficients indicated dislocation of the nodule volumes. Dislocation magnitude was d = (5.6 ± 3.1) mm. Organ filling was not correlated with deformation or dislocation. Volumes were covered by the 95% isodose in 96% of cases when rigid registration was performed versus 75% of cases when deformed.
Rigid image coregistration is sufficiently accurate in this setting. The results indicate that the deformable registration tends to shrink the voxels and to dislocate the ROI, the adopted expansion for the recurrence volume adequately accounts for the observed deformation and dislocation, provided that organ filling is controlled.
评估多参数磁共振（mpMR）与计算机断层扫描（CT）图像之间的刚性配准在前列腺床癌复发放射治疗中的准确性。
在一项关于前列腺床复发挽救性放射治疗的前瞻性研究中纳入的53例患者（59个结节）适合进行分析。患者在相同治疗体位下接受放疗前mpMR检查和计划CT扫描，并控制器官充盈情况。在mpMR图像上勾勒出复发部位，并使用刚性和可变形配准将轮廓转移到计划CT图像上。通过量化变形的数学算子（雅可比行列式和向量旋度）和相似性指数（骰子系数和杰卡德系数）评估配准情况。评估剂量覆盖情况。
可变形配准未改变体积（p = 0.92，MW检验）。雅可比系数和向量旋度未显示重要的图像变形。骰子系数和杰卡德系数表明结节体积存在错位。错位幅度为d =（5.6±3.1）mm。器官充盈与变形或错位无关。进行刚性配准时，96%的病例中体积被95%等剂量线覆盖，而进行可变形配准时为75%。
在这种情况下，刚性图像配准足够准确。结果表明，可变形配准倾向于使体素缩小并使感兴趣区域（ROI）错位，只要控制了器官充盈，对复发体积采用的扩展足以考虑到观察到的变形和错位。
