positron radioactivity

例句：

1. 1. The positron radioactivity in the sample is very low.
   样本中的正电子放射性非常低。
2. 2.This material has high positron radioactivity, which makes it suitable for medical applications.
   这种材料具有高正电子放射性，使其适用于医疗应用。
3. 3. The study of positron radioactivity has led to significant advancements in nuclear medicine.
   正电子放射性研究已导致核医学的重大进步。