About Cesium-131

Not all seed brachytherapy radioisotopes are the same. You and your doctor should choose the best isotope for your treatment. Ask your doctor about Cesium-131.

Advantages of Cesium-131 Brachytherapy Seeds¹

Higher Energy

Cesium-131 has a higher average energy than any other commonly used prostate brachytherapy isotope on the market. Energy is a key factor in how uniformly the radiation dose can be delivered throughout the prostate. This is known as homogeneity. Early studies demonstrate Cesium-131 implants are able to deliver the required dose while maintaining good homogeneity across the gland itself and potentially reducing unnecessary dose to critical structures such as the urethra and rectum.²

Shorter Half-Life

Cesium-131 has the shortest half-life of any prostate brachytherapy isotope at 9.7 days. Cesium-131 delivers 90% of the prescribed dose to the prostate in just 33 days compared to 58 days for Palladium and 204 days for Iodine-125. The short half-life of Cs-131 reduces the duration of time during which the prostate receives the irritating effects of the radiation. Early studies demonstrate Cesium-131 is well tolerated with minimal to moderate urinary symptoms that resolve relatively rapidly, within approximately 4-8 weeks.²

Higher Biologically Effective Dose

Another benefit to the short half-life of Cesium-131 is what is known as the "biological effective dose" or BED. BED is a way for providers to predict how an isotope will perform against slow versus fast growing tumors. Studies have shown Cesium-131 is able to deliver a higher BED across a wide range of tumor types than either Iodine-12S or Palladium-103. Although prostate cancer is typically viewed as a slow growing cancer it can present with aggressive features. Cesium-131's higher BED may be particularly beneficial in such situations.³

1. Chen, Z., Dose rate constant of a Cesium-131 interstitial brachytherapy seed measured by thermoluminescent dosimetry and gamma-ray spectrometry: Medical Physics. 32 (11), November 2005.
   
   
2. Prestidge B.R., Bice W.S., Jurkovic I., et al. Cesium-131 Permanent Prostate Brachytherapy: An Initial Report. Int. J. Radiation Oncology Biol. Phys. 2005; 63 (1): 5336-5337.
   
   
3. Armpilia CI, Dale RG, Coles IP, et al. The Determination of Radiobiologically Optimized Half-lives for Radionuclides Used in Permanent Brachytherapy Implants. Int. J. Radiation Oncology Biol. Phys. 2003; 55 (2): 378-385.