Department of Radiotherapy, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha, Maharashtra, India.
Department of Radiology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha, Maharashtra, India.
J Cancer Res Ther. 2024 Jul 1;20(5):1533-1538. doi: 10.4103/jcrt.jcrt_246_23. Epub 2024 Jan 22.
Although radiotherapy treatment planning (RTP) for head and neck cancers (HNCs) is based on contrast enhanced computed tomography (CECT), soft tissue contrasts are better evident on magnetic resonance imaging (MRI). We therefore evaluated dose-volume histogram (DVH) parameters along with concordance index (ConI), conformity index (CI), and homogeneity index (HI) of planning target volume (PTV) of GTV delineated on CECT vs MRI in HNCs enrolled for intensity modulated radiotherapy (IMRT).
Forty consecutive HNCs were enrolled in this study. All underwent CECT and MRI simulations with immobilization devices. GTVp and GTVn were delineated independently on CECT and MRI images. Corresponding MRI volumes were then copied to CECT. IMRT plans were generated on the CECT incorporating PTV margins. DVH parameters of PTVpn for both CECT and MRI were compared. In addition, mean (±SD) percentage difference of GTVp, GTVn, GTVpn, ConI, CI, and HI were evaluated using paired t-test.
The GTVp (P = 0.005), GTVn (P = 0.009), and GTVpn (P < 0.001) delineated on MRI were found to be significantly larger than GTV delineated on CECT. In eight patients, GTV outlined on CECT were larger than MRI. Significant mean differences in CECT vs MRI of CI (P < 0.001), HI (P < 0.001), ConI (P < 0.001), and DVH parameters (D2, D95, D98, V95, and V100 all P < 0.001; D50: P = 0.009) were noted.
The GTVs and corresponding PTVs were significantly larger on MRI compared to CECT. This resulted in significant differences in DVH parameters, CI, ConI, and HI. This could be improved by co-registered MRI-CECT volumes during routine IMRT treatment planning for HNCs.
虽然头颈部癌症（HNC）的放射治疗计划（RTP）基于对比增强计算机断层扫描（CECT），但磁共振成像（MRI）上软组织对比度更好。因此，我们评估了在接受调强放疗（IMRT）的 HNC 中，基于 CECT 与 MRI 勾画 GTV 所得到的计划靶区（PTV）的剂量体积直方图（DVH）参数，以及一致性指数（ConI）、适形指数（CI）和均匀性指数（HI）。
本研究纳入了 40 例连续的 HNC 患者。所有患者均接受了带有固定装置的 CECT 和 MRI 模拟检查。GTVp 和 GTVn 分别在 CECT 和 MRI 图像上独立勾画。然后将相应的 MRI 体积复制到 CECT 上。在 CECT 上生成包含 PTV 边界的 IMRT 计划。比较了 CECT 和 MRI 上 PTVpn 的 DVH 参数。此外，还使用配对 t 检验评估了 GTVp、GTVn、GTVpn、ConI、CI 和 HI 的平均（±SD）百分比差异。
MRI 上勾画的 GTVp（P=0.005）、GTVn（P=0.009）和 GTVpn（P<0.001）明显大于 CECT 上勾画的 GTV。在 8 例患者中，CECT 上勾画的 GTV 大于 MRI。在 CECT 与 MRI 之间，CI（P<0.001）、HI（P<0.001）、ConI（P<0.001）和 DVH 参数（D2、D95、D98、V95 和 V100 均 P<0.001；D50：P=0.009）存在显著的平均差异。
与 CECT 相比，MRI 上的 GTV 及其相应的 PTV 明显更大。这导致了 DVH 参数、CI、ConI 和 HI 的显著差异。在常规的 HNC 调强放疗计划中，通过对 CECT 和 MRI 进行配准，可以改善这些差异。
