Beta Particles

Radioisotopes with high proportion of beta emission have been used clinically and represent the largest group used in therapy. Beta particles have a finite and limited range in tissues and dissipate most of their energy (~95%) within an organ. While beta particles are ideal for treating larger tumors because of longer path range in tissues, much of their energy (up to 99.9%) can fall outside the small diameter microscopic tumors (5). A plastic syringe shield is used for pure beta emitters to avoid bremstrahlung that would contribute radiation dose to the hands. Several beta emitters have found appropriate role in the palliation of patients with painful bone metastases (6,7). In theory, the dose rate of particle emission has some bearing on treatment effects. Generally, radionuclides with higher dose rates are effective in treating tumors with shorter cell cycle time, that is, rapidly proliferating cells and vice versa (8,9). Radioisotopes without any gamma ray emission provide the advantage of convenient outpatient treatment, because of the lack of gamma radiation.

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