Not All Seeds Are Created Equal

Cancer Treatment with Cesium Blu Brachytherapy Seeds by Isoray

Not all seed brachytherapy radioisotopes are the same. You and your doctor should choose the best isotope for your cancer treatment. Ask your doctor about Cesium Blu by Isoray.

Higher Energy

Cs-131 has a higher average energy than any other commonly used prostate cancer brachytherapy isotope on the market. Energy is a key factor in how uniformly the radiation dose can be delivered throughout the prostate. (1)

Shorter Half-Life

Cs-131 has the shortest half-life of any commonly used prostate cancer brachytherapy isotope at 9.7 days. Cs-131 delivers 90% of the prescribed dose to the prostate gland in just 33 days compared to 58 days for Pd-103 and 204 days for I-125. (2)

Improved Coverage of the Prostate

Permanent prostate cancer brachytherapy utilizing Cs-131 seeds allows for better dose homogeneity and the sparing of the urethra and rectum while providing comparable prostate coverage compared to other seeds with comparable or fewer seeds and needles. (3, 4, 5, 6)

Rapid Resolution of Side effects

Studies demonstrate that objective measures of common prostate side-effects showing an early peak in symptoms in the 2-week to 1-month time frame. Resolution of morbidity resolved rapidly within 4-6 months. (7, 8, 9, 10)

Higher Biologically Effective Dose

Another benefit to the short half-life of Cs-131 is what is known as the “biological effective dose” or BED. Studies have shown Cs-131 is able to deliver a higher BED across a wide range of tumor types than either I-125 or Pd-103. (11)

PSA Control

Investigators tracking PSA in both single arm and randomized prostate cancer treatment trials have concluded Cs-131’s PSA response rates show similar early tumor control to I-125, long considered the gold standard in permanent seed brachytherapy. (8, 12, 13)

“Cesium makes a good doc an even better doc.”

Joe R. – San Fransisco, CA
Cesium Patient

Why Cesium Blu?

With a shorter half-life and higher energy than other commonly used radioisotopes, Cesium-131 by Isoray has been shown to be a highly effective cancer treatment when planned appropriately. (10, 14, 17)

  • Quick Recovery
  • Speedy Return to PSA Baseline

Your Isotope Choice Makes a Difference


Introduced in 1986
  • 17 Day Half Life (18)

  • 20.8 Kev

  • 58 Days for 90% Dose

  • 125 Gy Total Dose

  • Detectable in the body for 170 Days


Introduced in 1965
  • 60 Day Half Life (18)

  • 28.5 Kev

  • 204 Days for 90% Dose

  • 145 Gy Total Dose

  • Detectable in the body for 600 Days


Patients & Families

Find a Doctor Near You

A diagnosis is just the first step toward treating your cancer. We are here to help you make an informed treatment decision with your doctor so you can begin living your life again.



1. 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.

2. Neill B, et al. The Nature and Extent of Urinary Morbidity in Relation to Prostate Brachytherapy Urethral Dosimetry. Brachytherapy 2007:6(3)173-9.

3. Musmacher JS, et al. Dosimetric Comparison of Cesium-131 and Palladium-103 for Permanent Prostate Brachytherapy. Int. J. Radiation Oncology Biol. Phys. 2007:69(3)S730-1.

4. Yaparpalvi R, et al. Is Cs-131 or I-125 or Pd-103 the “Ideal” Isotope for Prostate Boost Brachytherapy? A Dosimetric View Point. Int. J. Radiation Oncology Biol. Phys. 2007:69(3)S677-8.

5. Sutlief S, et al. Cs-131 Prostate Brachytherapy and Treatment Plan Parameters. Medical Physics 2007:34(6)2431.

6. Yang R, et al. Dosimetric Comparison of Permanent Prostate Brachytherapy Plans Utilizing Cs-131, I-125 and Pd-103 Seeds. Medical Physics 2008:35(6)2734.

7. Prestidge B, et. al. Clinical Outcomes of a Phase-II, Multi-institutional Cesium-131 Permanent Prostate Brachytherapy Trial. Brachytherapy. 2007: 6 (2)78.

8. Moran B, et al. Cesium-131 Prostate Brachytherapy: An Early Experience. Brachytherapy 2007:6(2)80.

9. Jones A, et al. IPSS Trends for Cs-131 Permanent Prostate Brachytherapy. Brachytherapy 2008:7(2)194.

10. DeFoe SG, et al. Is There Decreased Duration of Acute Urinary and Bowel Symptoms after Prostate Brachytherapy with Cesium 131 Radioisotope? Int. J. Radiation Oncology Biol. Phys. 2008:72(S1)S317.

11. 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.

12. Bice W, et. al. Recommendations for permanent prostate brachytherapy with 131Cs: a consensus report from the Cesium Advisory Group. Brachytherapy 2008:7(4)290-296.

13. Platta CS, et al. Early Outcomes of Prostate Seed Implants with 131Cs: Toxicity and Initial PSA Dynamics from a Single Institution. Int. J. Radiation Oncology Biol. Phys. 2008:72(S1)S323-4.

14. Tomaszewski JJ, et al. Cesium 131 versus iodine 125 implants for prostate cancer: evaluation of early PSA response. The Canadian Journal of Urology. 2010;17(5): 5360-5364.

15. R.M. Benoit, R.P. Smith, S. Beriwal. Five Year Prostate-specific Antigen Outcomes after Caesium Prostate Brachytherapy. Clinical Oncology. 26 (2014) 776 780.

16. Brian J. Moran, MD, Michelle H. Braccioforte, MPH. Prostate Cancer Foundation of Chicago, Westmont, IL. PSA Outcomes in a Single Institution, Prospective Randomized 131Cs/125I Permanent Prostate Brachytherapy Trial Abstracts / Brachytherapy. 13 (2014) S15eS126.

17. Amit B. Shah, MD, Arnav A. Shah, Gregory A. Fortier, MD. Radiation Oncology, York Cancer Center, Wellspan Health, York, PA. A Comparison of AUA Symptom Scores following Permanent Low-Dose-Rate Prostate Brachytherapy with Iodine-125 and Cesium-131, Abstracts / Brachytherapy 12 (2013) S11eS77.

18. Herstein A, Wallner K, Merrick G, Mitsuyama H, Armstrong J, True L, Cavanagh W, Butler W. I-125 versus Pd-103 for low-risk prostate cancer: long-term morbidity outcomes from a prospective randomized multicenter controlled trial. Cancer J. 2005 Sep-Oct;11(5):385-9.