立体定向放射治疗肺癌中呼吸运动频率与图像扫描时间对靶体积定位成像结果的影响

目的：研究立体定向放射治疗肺癌中呼吸运动频率与图像扫描时间对靶体积定位成像结果的影响。方法：利用自行研制的呼吸运动模拟器，比较在不同扫描方式时运动成像的结果。结果：普通CT扫描运动的模拟病灶，当模拟病灶动度的1个周期等于每层的扫描时间或短于每层扫描时间时，普通CT不会丢失扫描信号。相反，如果1个运动周期长于每层扫描时间时，普通CT结果会丢失部分信号。而螺旋CT扫描运动的模拟病灶，无论模拟病灶的3个运动周期的哪一组，螺旋CT结果均丢失部分扫描信号。结论：动态下成像定位病灶时，每层扫描时间等于或大于1个呼吸周期的普通CT优于快速扫描成像的螺旋CT。

The Effects of Respiratory Movement Frequency and Scanning Time on the Image Results in the Treatment of Lung Cancer by Stereotactic Radiotherapy

Objective: To study the effects of respiratory movement frequency and scanning time on the image results in the treatment of lung cancer by stereotactic radiotherapy. Methods: We designed a device to simulate the respiratory movement and observed the effect of different frequency of the moving ball on the scanning results while the ball moving at different moving extent and different moving direction under the different scanning mode. Results: There was no scanning information lost when the moving ball moved on the direction of X and Y-axis and on the direction of Z-axis while the moving extent was 0.5 cm using general CT and spiral CT. When the moving extent was 1 cm and 2 cm along the direction of Z-axis, using general CT, and the moving cycle of the ball was equal to or shorter than the scanning time for one slice. There was no scanning information lost. But the scanning information lost while the moving cycle of the ball was longer than the scanning time for one slice. Scanning information lost occurred when using spiral CT, and the moving extent was 1 cm and 2 cm along the direction of Z-axis. Conclusion: Using general CT, the moving cycle of the ball is equal to or shorter than the scanning time for one slice, and the imaging results are better than that using spiral CT.