Tsunashima Yoshikazu, Sakae Takeji, Shioyama Yoshiyuki, Kagei Kenji, Terunuma Toshiyuki, Nohtomi Akihiro, Akine Yasuyuki
Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennoudai Tsukuba, Ibaraki 305-8575, Japan.
Int J Radiat Oncol Biol Phys. 2004 Nov 1;60(3):951-8. doi: 10.1016/j.ijrobp.2004.06.026.
The purpose of this study is to investigate the correlation between the respiratory waveform measured using a respiratory sensor and three-dimensional (3D) tumor motion.
A laser displacement sensor (LDS: KEYENCE LB-300) that measures distance using infrared light was used as the respiratory sensor. This was placed such that the focus was in an area around the patient's navel. When the distance from the LDS to the body surface changes as the patient breathes, the displacement is detected as a respiratory waveform. To obtain the 3D tumor motion, a biplane digital radiography unit was used. For the tumor in the lung, liver, and esophagus of 26 patients, the waveform was compared with the 3D tumor motion. The relationship between the respiratory waveform and the 3D tumor motion was analyzed by means of the Fourier transform and a cross-correlation function.
The respiratory waveform cycle agreed with that of the cranial-caudal and dorsal-ventral tumor motion. A phase shift observed between the respiratory waveform and the 3D tumor motion was principally in the range 0.0 to 0.3 s, regardless of the organ being measured, which means that the respiratory waveform does not always express the 3D tumor motion with fidelity. For this reason, the standard deviation of the tumor position in the expiration phase, as indicated by the respiratory waveform, was derived, which should be helpful in suggesting the internal margin required in the case of respiratory gated radiotherapy.
Although obtained from only a few breathing cycles for each patient, the correlation between the respiratory waveform and the 3D tumor motion was evident in this study. If this relationship is analyzed carefully and an internal margin is applied, the accuracy and convenience of respiratory gated radiotherapy could be improved by use of the respiratory sensor.Thus, it is expected that this procedure will come into wider use.
本研究旨在探讨使用呼吸传感器测量的呼吸波形与三维（3D）肿瘤运动之间的相关性。
使用一种利用红外光测量距离的激光位移传感器（LDS：基恩士LB - 300）作为呼吸传感器。将其放置在使焦点位于患者肚脐周围的区域。当患者呼吸时，LDS到体表的距离发生变化，该位移被检测为呼吸波形。为了获得3D肿瘤运动，使用了双平面数字放射摄影设备。对于26例患者肺部、肝脏和食管中的肿瘤，将波形与3D肿瘤运动进行比较。通过傅里叶变换和互相关函数分析呼吸波形与3D肿瘤运动之间的关系。
呼吸波形周期与肿瘤头 - 尾向和背 - 腹向运动的周期一致。无论所测量的器官如何，在呼吸波形与3D肿瘤运动之间观察到的相位偏移主要在0.0至0.3秒的范围内，这意味着呼吸波形并不总是如实地表达3D肿瘤运动。因此，得出了由呼吸波形指示的呼气期肿瘤位置的标准差，这对于提示呼吸门控放疗情况下所需的内边界应该是有帮助的。
尽管本研究中每个患者仅从少数呼吸周期获得数据，但呼吸波形与3D肿瘤运动之间的相关性是明显的。如果仔细分析这种关系并应用内边界，则使用呼吸传感器可提高呼吸门控放疗的准确性和便利性。因此，预计该方法将得到更广泛的应用。
