title: Dosimetric quality and evolution of edema after low-dose-rate brachytherapy for small prostates: implications for the use of newer isotopes.
abstract: OBJECTIVE
  To characterize prostate swelling and dosimetry in patients with small prostate volumes (PVs) undergoing brachytherapy.
  
  
  METHODS
  We studied 25 patients with PV <25 cc (range, 15.1-24.8) and 65 patients with PV ≥25 cc (range, 25.0-66.2) based on three-dimensional ultrasound contours who underwent brachytherapy monotherapy with intraoperative planning. Postoperative Days 1 and 30 dosimetry was done by CT-MRI fusion.
  
  
  RESULTS
  Small PVs had greater Day 1 swelling than large PVs (32.5% increase in volume vs. 23.7%, p = 0.04), but by Day 30, swelling was minimal and not significantly different (p = 0.44). Small PVs had greater seed and needle densities at implant (p < 0.001). Rectal and urethral doses were nearly identical by Day 30 (small PV rectum receiving 100% of the prescription dose [145 Gy] [V100] = 0.32 cc; large PV rectum V100 = 0.33 cc, p = 0.99; small PV urethra receiving 150% of the prescription dose [145 Gy] [V150] = 0.20, large PV urethra V150 = 0.20, p = 0.91). Swelling at Day 1 created some cool implants (rate dose that covers 90% of the prostate volume [D90 <140 Gy = 12.0% and 9.4% for the small and large PV groups, respectively, p = 0.71), but Day 30 planning target volume coverage was excellent (rate D90 <140 Gy = 0% for both groups).
  
  
  CONCLUSIONS
  Although smaller prostates have greater Day 1 swelling, good Day 30 dosimetry can be achieved, making them excellent candidates for (125)I seeds (half-life [t½] = 60 days). Smaller prostates may be suboptimal for shorter t½ sources such as (131)Cs (t½ = 9.7 days), in which the majority of the dose may be delivered to an edematous gland, unless the planning is adjusted to anticipate the edema.
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Konstantin A
authors.initials: KA
authors.lastname: Kovtun
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Luciant
authors.initials: L
authors.lastname: Wolfsberger
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Niedermayr
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Emily N
authors.initials: EN
authors.lastname: Sugar
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Powell L
authors.initials: PL
authors.lastname: Graham
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Yonina
authors.initials: Y
authors.lastname: Murciano-Goroff
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Clair
authors.initials: C
authors.lastname: Beard
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Anthony V
authors.initials: AV
authors.lastname: D'Amico
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Martin
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Orio
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA. Electronic address: pnguyen@LROC.harvard.edu.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Nguyen
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D004487:Edema / Q000209:etiology*; D006801:Humans; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011467:Prostate / Q000033:anatomy & histology*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries; D011874:Radiometry; D012007:Rectum; D012189:Retrospective Studies; D014521:Urethra
chemical_list: D007457:Iodine Radioisotopes
keywords: (125)I seeds; Low dose rate; Prostate brachytherapy; Small prostate