Skarsgard L D, Henkelman R M, Eaves C J
J Can Assoc Radiol. 1980 Mar;31(1):3-12.
Beams of negative pi-mesons (pions) have depth-dose characteristics which are favorable for radiation therapy. As well, the densely ionizing radiations resulting from pion capture give pion beams an increased RBE and reduced OER, largely confined to the treatment volume. Three facilities capable of testing pion beams for therapy now exist: TRIUMF in Vancouver, LAMPF in New Mexico and SIN in Villigen, Switzerland. Patient treatment is already underway at LAMPF and will commence at TRIUMF in November, 1979, and at SIN in 1980. Pre-clinical studies of the pion beam at TRIUMF have confirmed the predicted physical and radiobiologic properties of this new type of radiation. Fractionated irradiation of mouse skin suggests an RBE of 1.4 -- 1.6 for small treatment volumes receiving 10 dose fractions of peak pions. Single dose studies with cultured cells give an RBE for peak pions of 1.2 -- 1.5 and an oxygen gain factor of 1.2. The results are generally in good agreement with those obtained at LAMPF and SIN. Techniques have been developed which facilitate the delivery of well-defined dose distributions with uniform biologic effect throughout the treatment volume.
负π介子束具有有利于放射治疗的深度剂量特性。此外，π介子俘获产生的高密度电离辐射使π介子束的相对生物效应增加，氧增强比降低，且主要局限于治疗体积内。目前有三个能够测试用于治疗的π介子束的设施：温哥华的 TRIUMF、新墨西哥州的 LAMPF 和瑞士维利根的 SIN。LAMPF 已经开始对患者进行治疗，TRIUMF 将在 1979 年 11 月开始，SIN 将在 1980 年开始。TRIUMF 对π介子束的临床前研究证实了这种新型辐射所预测的物理和放射生物学特性。对小鼠皮肤进行分次照射表明，对于接受 10 次峰值π介子剂量分割的小治疗体积，相对生物效应为 1.4 - 1.6。对培养细胞进行的单剂量研究得出，峰值π介子的相对生物效应为 1.2 - 1.5，氧增强系数为 1.2。这些结果与在 LAMPF 和 SIN 获得的结果总体上吻合良好。已经开发出了一些技术，这些技术有助于在整个治疗体积内提供具有均匀生物效应的明确剂量分布。
