title: Focal high-dose-rate brachytherapy: a dosimetric comparison of hemigland vs. conventional whole-gland treatment.
abstract: OBJECTIVE
  To determine the utility of focal high-dose-rate brachytherapy for localized prostate cancer, we investigated the impact on target coverage and dose to organs at risk (OARs) with hemigland (HG) compared with whole-gland (WG) treatment.
  
  
  METHODS
  A total of 10 WG implants were used to generate 10 WG and 20 HG (left and right) treatment plans optimized with the inverse planning simulation annealing algorithm using Oncentra MasterPlan (Nucletron B.V., Veenendaal, The Netherlands). The standard distribution of 17-18 catheters designed for WG was used to generate HG plans. The same OARs namely bladder, rectum, and urethra contours and dose constraints were applied for HG and WG plans. The HG contour was a modification of the WG contour whereby the urethra divided the prostate into HGs. The prescription dose was 7.25 Gy×6. Evaluated dose parameters were target dose D90, V100, and V150 and D0.1 cc, D1 cc, and D2 cc to OARs.
  
  
  RESULTS
  The HG plans had a D90, V100, and V150 to the HG target of 112%, 97.6%, and 33.8%, respectively. The WG plans had a D90, V100, and V150 to the WG target of 108%, 98.8%, and 26.5%, respectively. The OAR D2 cc doses were significantly lower in HG vs. WG plans: rectum (53.1% vs. 64.1%, p<0.0001), bladder (55.9% vs. 67.5%, p<0.0001), and urethra (69.3% vs. 95.2%, p<0.0001).
  
  
  CONCLUSIONS
  In the present model, HG plans yielded a statistically significant decreased radiation dose to OARs and provided complete target coverage with a catheter array designed for WG coverage. The good dosimetry results obtained in this study support the feasibility of HG brachytherapy by using a subset of the WG catheter array. Catheter distribution and dosimetry refinements tailored to subtotal prostate brachytherapy should be explored to see if further improvements in dosimetry can be achieved.
authors: Department of Radiation Oncology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA; Jonsson Comprehensive Cancer Center, Los Angeles, CA.
authors: Mitchell
authors: M
authors: Kamrava
authors: Melody P
authors: MP
authors: Chung
authors: Oluwatosin
authors: O
authors: Kayode
authors: Jason
authors: J
authors: Wang
authors: Leonard
authors: L
authors: Marks
authors: Patrick
authors: P
authors: Kupelian
authors: Michael
authors: M
authors: Steinberg
authors: Sang-June
authors: SJ
authors: Park
authors: D Jeffrey
authors: DJ
authors: Demanes
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D058958:Organs at Risk; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D011882:Radiotherapy, High-Energy / Q000379:methods*; D012007:Rectum / Q000528:radiation effects; D013997:Time Factors; D001743:Urinary Bladder / Q000528:radiation effects
keywords: Brachytherapy; Focal therapy; Prostate