Department of Radiation Oncology, Cancer Hospital of Fujian Medical University, 91 Maluding, Fuma Road, Fuzhou, 350014, People's Republic of China.
Jpn J Radiol. 2013 Sep;31(9):593-9. doi: 10.1007/s11604-013-0225-5. Epub 2013 Jun 9.
Our aim was to evaluate the volumetric and dosimetric changes of target volumes and organs at risk (OARs) during intensity-modulated radiation therapy (IMRT) for locoregionally advanced nasopharyngeal carcinoma (NPC) and the necessity of replanning.
Twenty locoregionally advanced NPC patients treated by concurrent chemotherapy and IMRT were included. CT and MR images were acquired before treatment and at weeks 2, 3, 4, 5 and 6 during treatment. The target volumes and OARs were contoured based on the fused CT-MRI images and hybrid plans were generated. The changes of volume and dosimetry were measured by comparing original plan and hybrid plans.
Significant volumetric changes of target volumes and parotid gland were observed. The primary nasopharyngeal tumor (GTVnx), CTV1, involved lymph nodes (GTVnd) and left and right parotid glands, shrank at a mean rate of 14.7, 11.56, 11.40, 6.54 and 6.78 % per treatment week, respectively. There were no significant dosimetric changes in GTVnx, GTVnd, CTV1, spinal cord and brain stem while the differences of dose to left and right parotid glands were significant (F = 6.73, P = 0.007; F = 7.43, P = 0.007).
Remarkable volumetric changes were observed. However, the dosimetric changes were inconspicuous except for the parotid. Replanning might contribute to protect the parotid gland.
我们旨在评估局部晚期鼻咽癌患者接受调强放疗期间靶区和危及器官（OARs）的体积和剂量变化，以及是否需要重新计划。
纳入 20 例接受同期放化疗的局部晚期鼻咽癌患者。在治疗前和治疗期间的第 2、3、4、5 和 6 周采集 CT 和 MRI 图像。基于融合 CT-MRI 图像对靶区和 OARs 进行轮廓勾画，并生成混合计划。通过比较原始计划和混合计划来测量体积和剂量学变化。
观察到靶区和腮腺体积的显著变化。原发鼻咽肿瘤（GTVnx）、CTV1、受累淋巴结（GTVnd）和左、右腮腺在每个治疗周期分别以 14.7%、11.56%、11.40%、6.54%和 6.78%的平均速率缩小。GTVnx、GTVnd、CTV1、脊髓和脑干的剂量学变化不显著，而左、右腮腺的剂量差异显著（F = 6.73，P = 0.007；F = 7.43，P = 0.007）。
观察到明显的体积变化，但除腮腺外，剂量学变化不明显。重新计划可能有助于保护腮腺。
