Beta radiation from radium, radon, and radium D-E has been used in the treatment of certain external ocular conditions for about 40 years because of the relatively superficial effects and accurate localization of the radiation. More recently, radioactive strontium (Sr90)-yttrium (Y90) applicators have become available as a source of beta particles or electrons for ocular use. The early enthusiastic reports of the efficacy of beta radiation have been tempered by the appearance of certain secondary complications including cataract. Therefore, it becomes more important that the clinician be aware of the sources, rationale, uses, contraindications, dosages, and dangers of beta therapy.
Characteristics of Various Sources of Beta Radiation
Various sources and applicators have differing characteristics in surface output, depth dose, and amount of gamma rays. A comparison of available data1 on these applicators is given in table 1. The differences in the construction of the applicators, their