Gai Xiujuan, Wei Yumei, Tao Hengmin, Zhu Jian, Li Baosheng
School of Medicine and Life Sciences, University of Jinan-Shandong Academy of Medical Sciences, Shandong, China.
Department of Radiation Oncology VI, Shandong Cancer Hospital Affiliated to Shandong University, Jinon, Shandong, China.
Oncotarget. 2017 Apr 18;8(16):27529-27540. doi: 10.18632/oncotarget.16770.
To study the necessity of repeat computed tomography (CT) scan and replanning and know a more accurate time using weekly kilovoltage cone beam computed tomography (kV-CBCT) scans for patients with nasopharyngeal carcinoma (NPC) during radiotherapy.
Thirteen NPC patients treated with IMRT were enrolled into this prospective study. Weekly pretreatment kV-CBCT scans were performed on the 1st, 6th, 11st, 16th, 21st and 26th radiation time, respectively. Target delineations were contoured on all fractionated CBCT images, including the gross tumor volume of the primary nasopharyngeal tumor (GTVnx) and parotid glands. The volumes of GTVnx and parotid glands were calculated automatically using the Pinnacle3 8.0 system. Compared to the original GTVnx, the percentage of shrinking volume (ΔP) ≥ 50% was considered significantly.
As the radiation proceeding, the GTVnx had a trend of shrinkage. Of all 13 patients, 11 cases (84.6%) had the volume shrinking ≥ 50% before the 21st radiation and 12 cases (92.3%) before the 26th radiation. And the parotid volume decreased significantly in the first four-week radiation, 6.45 ± 3.16cm3 (range, 3.06-13.9cm3) for the left parotid gland and 5.78 ± 2.39cm3 (range, 2.70-11.2cm3) for the right. Furthermore, only a little displacement occurred to bilateral parotid glands.
The replanning for NPC patients with IMRT is necessary, and the time between the 21st to 25th radiations is appropriate.
研究鼻咽癌（NPC）患者在放疗期间重复计算机断层扫描（CT）及重新计划的必要性，并了解使用每周千伏锥形束计算机断层扫描（kV-CBCT）扫描的更准确时间。
13例接受调强放疗（IMRT）的NPC患者纳入本前瞻性研究。分别在第1、6、11、16、21和26次放疗时进行每周一次的治疗前kV-CBCT扫描。在所有分次CBCT图像上勾勒靶区轮廓，包括鼻咽原发肿瘤大体肿瘤体积（GTVnx）和腮腺。使用Pinnacle3 8.0系统自动计算GTVnx和腮腺的体积。与原始GTVnx相比，体积缩小百分比（ΔP）≥50%被认为具有显著性。
随着放疗进行，GTVnx有缩小趋势。13例患者中，11例（84.6%）在第21次放疗前体积缩小≥50%，12例（92.3%）在第26次放疗前体积缩小≥50%。并且腮腺体积在前四周放疗中显著减小，左侧腮腺为6.45±3.16cm³（范围3.06 - 13.9cm³），右侧腮腺为5.78±2.39cm³（范围2.70 - 11.2cm³）。此外，双侧腮腺仅有轻微移位。
IMRT治疗的NPC患者重新计划是必要的，第21至25次放疗之间的时间是合适的。
