Science & Technology

Facts about beta radiation

Natural elements such as carbon 14 and potassium 40, and artificially produced metals such as strontium 90, emit beta particles that contain radioactive energy. Beta radiation has been used in ophthalmology for many years. It usually only becomes a health risk if exposure involves high doses over many years.

Strontium 90 (⁹⁰Sr) has been used for over 40 years to treat eye disorders including pterygium, AMD, and uveal melanoma. In recent years new delivery techniques have evolved that enable retinal surgeons to deliver highly targeted, precisely calibrated doses of radiation.

Low-dose radiation has been shown to shrink ocular tumors, and affects subfoveal neovascularization in 3 ways:

• Causing stenosis and the closure of small capillaries
• Decreasing endothelial cell migration and new capillary formation (antiangiogenesis)
• Diminishing inflammatory reactions through its effects on white blood cells

External beam radiation has been studied in patients with AMD and is still in use for the treatment of ocular malignancies, but fell out of use in AMD after the introduction of anti-VEGF therapy. The following features distinguish strontium 90 beta radiation from external beam radiation.

• The radiation delivered is only 2.3 MeV* with strontium 90, compared with 80 to 200 MeV for proton beam radiation
• Beta radiation has a limited depth of penetration and rapid dissipation, making it safer for surrounding healthy tissues
• Although the localized therapeutic dose to the retina is high, the amount of whole-body radiation exposure is minimal

*MeV = million electronvolts.

Beta radiation FAQs