The limited range of electrons yields depth doses and dose distributions offering the possibility to spare the tissue situated behind the tumor and to deliver a smaller volume dose. Electrons, therefore, can produce dose distributions being more favorable than those to be obtained with X-rays. The general radiation responses to electronic treatment are feeble. Clinical experiences also have shown that electrons are doing less harm to normal tissues than do X-rays. This may be derived from more important beta-effects and lesser alpha-effects of the electronic irradiation. The normal cells have a capacity for repair following beta-lesions which surpasses that of tumor cells, and thus, the electivity of electronic irradiation will increase and the clinical results are being explained. Schumacher (Berlin) has developed an improved fractionation schedule for electrons, using higher single doses once a week. The new schedule diminishes the number of tumor cells much more effectively than the conventional scheme utilized until now, and brings about, moreover, an additional protection of normal cells. Reoxygenation of anoxic tumor cells is sponsored. The clinical results from the new schedule (4262 cases) are very good.
电子束射程有限，其产生的深度剂量和剂量分布有可能保护肿瘤后方的组织，并给予较小体积的剂量。因此，电子束产生的剂量分布比X射线更有利。电子治疗的一般辐射反应较弱。临床经验也表明，电子束对正常组织的损害比X射线小。这可能源于电子辐射更重要的β效应和较小的α效应。正常细胞对β损伤后的修复能力超过肿瘤细胞，因此，电子辐射的选择性会增加，这也解释了临床结果。舒马赫（柏林）制定了一种改进的电子束分次照射方案，每周一次使用更高的单次剂量。新方案比目前使用的传统方案更有效地减少肿瘤细胞数量，而且还能额外保护正常细胞。促进了缺氧肿瘤细胞的再氧合。新方案（4262例）的临床效果非常好。
