Harada Keiichi, Katoh Norio, Suzuki Ryusuke, Ito Yoichi M, Shimizu Shinichi, Onimaru Rikiya, Inoue Tetsuya, Miyamoto Naoki, Shirato Hiroki
Department of Radiation Medicine, Hokkaido University Graduate School of Medicine, North-15 West-7, Kita-ku, Sapporo 060-8638, Japan.
Department of Radiation Oncology, Hokkaido University Hospital, North-14 West-5, Kita-ku, Sapporo 060-8638, Japan; Global Station for Medical Science and Engineering, Global Institution for Collaborative Research and Education, Hokkaido University Graduate School of Medicine, North-15 West-7, Kita-ku, Sapporo 060-8638, Japan.
Phys Med. 2016 Feb;32(2):305-11. doi: 10.1016/j.ejmp.2015.10.093. Epub 2016 Mar 2.
We investigated the usefulness of four-dimensional computed tomography (4DCT) performed before stereotactic body radiation therapy (SBRT) in determining the internal margins for peripheral lung tumors.
The amplitude of the movement of a fiducial marker near a lung tumor measured using the maximum intensity projection (MIP) method in 4DCT imaging was acquired before the SBRT (AmpCT) and compared with the mean amplitude of the marker movement during SBRT (Ampmean) and with the maximum amplitude of the marker movement during SBRT (Ampmax) using a real-time tumor-tracking radiotherapy (RTRT) system with 22 patients.
There were no significant differences between the means of the Ampmean and the means of the AmpCT in all directions (LR, P = 0.45; CC, P = 0.80; AP, P = 0.65). The means of the Ampmax were significantly larger than the means of the AmpCT in all directions (LR, P < 0.01; CC, P = 0.03; AP, P < 0.01). In the lower lobe, the mean difference of the AmpCT from the mean of the Ampmax was 5.7 ± 8.0 mm, 12.5 ± 16.7 mm, and 6.8 ± 8.5 mm in the LR, CC, and AP directions, respectively.
Acquiring 4DCT MIP images before the SBRT treatment is useful to establish the mean amplitude for a patient during SBRT but it underestimates the maximum amplitude during actual SBRT. Caution must be paid to determine the margin with the 4DCT especially for tumors at the lower lobe where it is of the potentially greatest benefit.
我们研究了立体定向体部放射治疗（SBRT）前进行的四维计算机断层扫描（4DCT）在确定周围型肺肿瘤内边界方面的实用性。
在22例患者中，使用实时肿瘤跟踪放射治疗（RTRT）系统，在SBRT之前获取4DCT成像中使用最大强度投影（MIP）方法测量的肺肿瘤附近基准标记物的运动幅度（AmpCT），并将其与SBRT期间标记物运动的平均幅度（Ampmean）以及SBRT期间标记物运动的最大幅度（Ampmax）进行比较。
在所有方向上，Ampmean的平均值与AmpCT的平均值之间均无显著差异（左右方向，P = 0.45；前后方向，P = 0.80；腹背方向，P = 0.65）。在所有方向上，Ampmax的平均值均显著大于AmpCT的平均值（左右方向，P < 0.01；前后方向，P = 0.03；腹背方向，P < 0.01）。在下叶，AmpCT与Ampmax平均值在左右、前后和腹背方向上的平均差值分别为5.7±8.0 mm、12.5±16.7 mm和6.8±8.5 mm。
在SBRT治疗前获取4DCT MIP图像有助于确定患者在SBRT期间的平均幅度，但会低估实际SBRT期间的最大幅度。使用4DCT确定边界时必须谨慎，尤其是对于下叶肿瘤，在该部位其潜在益处可能最大。
