Basic Research for four-dimensional stereotactic radiotherapy

我们利用两套BGO准直器、光电倍增器和准直器研制了一个四维（4-D，空间和时间）聚焦正电子发射定位器（FPEL）。当靶上的正电子发射体数量超过阈值时，控制45 MeV窄电子束以4D坐标中0.1mm的精度自动照射靶。建立小鼠模型，照射肿瘤，其中FDG积聚。使用FPEL，45-MeV电子束击中小鼠的肿瘤，其以类似于人类呼吸的幅度在束出口前移动。无金标的肿瘤在照射后一周内消失。为4D立体定向放射治疗奠定了基础。

We developed a four-dimensional (4-D, space and time) focal positron emission localizer, FPEL, using two sets of BGO scintillators, photo-electric multiplier, and collimators. A narrow (5-mm in diameter) 45-MeV electron beam was controlled to irradiate a target with an accuracy of 0.1mm in 4D coordinates automatically if the amount of positron emitters at the target exceeds the threshold. A mouse model was established to irradiate the tumor in which FDG is accumulated. Using the FPEL, 45-MeV electron beam hit the tumor in mice which move in front of the beam exit with the amplitude resembling human respiration. Tumor without fiducial gold marker disappeared within a week after the irradiation. Basis for 4D stereotacic radiotherapy was established successfully.