title: From whole gland to hemigland to ultra-focal high-dose-rate prostate brachytherapy: A dosimetric analysis.
abstract: OBJECTIVE
  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
  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).
  
  
  CONCLUSIONS
  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.
authors: Department of Oncology, University of Calgary, Calgary, Alberta T2N 4N2, Canada.
authors: Robyn
authors: R
authors: Banerjee
authors: Department of Radiation Oncology, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA.
authors: Sang-June
authors: SJ
authors: Park
authors: Department of Radiation Oncology, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA.
authors: Erik
authors: E
authors: Anderson
authors: Department of Radiation Oncology, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA.
authors: D Jeffrey
authors: DJ
authors: Demanes
authors: Department of Radiation Oncology, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA.
authors: Jason
authors: J
authors: Wang
authors: Department of Radiation Oncology, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA. Electronic address: mkamrava@mednet.ucla.edu.
authors: Mitchell
authors: M
authors: Kamrava
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D008297:Male; D058958:Organs at Risk; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011874:Radiometry; D011879:Radiotherapy Dosage; D012007:Rectum / Q000528:radiation effects; D014521:Urethra / Q000528:radiation effects; D001743:Urinary Bladder / Q000528:radiation effects
keywords: Focal therapy; HDR brachytherapy; Prostate cancer; Radiation therapy