von Essen C F, Blattmann H, Crawford J F, Fessenden P, Pedroni E, Perret C, Salzmann M, Shortt K, Walder E
Int J Radiat Oncol Biol Phys. 1982 Sep;8(9):1499-509. doi: 10.1016/0360-3016(82)90609-5.
The PIOTRON is a large solid angle superconducting channel built for the use of negative pi-mesons in radiotherapy. The pions are produced by protons of 590 MeV striking a target of molybdenum or beryllium. The pions are divided into 60 channels and deflected twice to enter the treatment volume radially. The momentum and the momentum band for all 60 channels can be chosen and the beam spot of Bragg peak pions at the isocenter of the applicator is a few centimeters in each direction. Dynamic scanning can thus achieve 3-dimensionally shaped treatment volumes. Two different methods are available: the ring scan, using changes of pion range; and the spot scan, involving translation of the patient through the fixed beam spot. Dose distributions of individual and multiple beams were plotted in a cylindrical water phantom. Radiobiological experiments with mammalian cells in gel and with mouse feet were performed. A special beam geometry using a sector of 15 beams was selected for the first treatments of patients with metastatic skin nodules. Six patients were treated. Acute skin reactions were scored and compared with those from orthovoltage therapy with comparable beam geometry. The RBE for 10 fractions is between 1.4 and 1.5. The next step involved treatment of patients inside water-bolus rings in preparation for dynamic therapy. Patients were then treated with the spot scan dynamic mode in the water bolus. The initial responses and reactions are favorable and confirm the feasibility and accuracy of dynamic pion therapy.
π介子放疗装置（PIOTRON）是一个大型的大立体角超导通道，专为在放射治疗中使用负π介子而建造。π介子由能量为590兆电子伏特的质子撞击钼或铍靶产生。π介子被分成60个通道，并经过两次偏转后径向进入治疗区域。所有60个通道的动量和动量范围都可以选择，并且在施源器等中心处布拉格峰π介子的束斑在各个方向上都有几厘米。因此，动态扫描可以实现三维形状的治疗区域。有两种不同的方法：环扫描，利用π介子射程的变化；以及点扫描，涉及患者通过固定束斑的平移。在圆柱形水模体中绘制了单束和多束的剂量分布。对凝胶中的哺乳动物细胞和小鼠足部进行了放射生物学实验。为转移性皮肤结节患者的首次治疗选择了一种使用15束扇形的特殊束几何结构。治疗了6名患者。对急性皮肤反应进行评分，并与具有可比束几何结构的深部X线治疗的反应进行比较。10次分割的相对生物效应（RBE）在1.4至1.5之间。下一步是在水垫环内对患者进行治疗，为动态治疗做准备。然后在水垫中以点扫描动态模式对患者进行治疗。初步反应良好，证实了动态π介子治疗的可行性和准确性。
