PURPOSE: To assess the magnitude of dosimetric reductions of a focal and ultra-focal high-dose rate (HDR) prostate brachytherapy treatment strategy relative to standard whole gland (WG) treatment.
METHODS AND MATERIALS: HDR brachytherapy plans for five patients treated with WG HDR monotherapy were optimized to assess different treatment strategies. Plans were generated to treat the hemigland (HG), one-third gland (1/3G), and one-sixth gland (1/6G), as well as to assess treating the WG with a boost to one of those sub-volumes (WG + HG, WG + 1/3G, WG + 1/6G). Dosimetric parameters analyzed included Target D90%, V100%, V150%, Bladder (B), Rectal (R), Urethral (U) D0.1, 1 and 2cc, Urethral V75%, and the V50% to the contralateral HG. Two-tailed t tests were used for comparison of means, and p-values less than 0.05 were considered statistically significant.
RESULTS: Target objectives (D90 > 100% and V100 > 97%) were met in all cases. Significant organs at risk dose reductions were achieved for all approaches compared with WG plans. 1/6G vs WG plans resulted in the greatest reduction in dose with a mean bladder D2cc 24.7 vs 64.8%, rectal D2cc 32.8 vs 65.3%, urethral D1cc 52.1 vs 103.8%, and V75 14.5 vs 75% (p < 0.05 for all comparisons).
CONCLUSION: Significant dose reductions to organs at risk can be achieved using HDR focal brachytherapy. The magnitude of the reductions achievable with treating progressively smaller sub-volumes suggests the potential to reduce morbidity, but the clinical impact on morbidity and tumor control remain to be investigated.
Banerjee R, Park SJ, Anderson E, Demanes DJ, Wang J, Kamrava M. Are you the author?
Department of Oncology, University of Calgary, Calgary, Alberta T2N 4N2, Canada; Department of Radiation Oncology, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA.
Reference: Brachytherapy. 2015 Feb 10. pii: S1538-4721(15)00002-1.