title: Novel prostate brachytherapy technique: improved dosimetric and clinical outcome.
abstract: OBJECTIVE
  Erectile dysfunction following prostate brachytherapy is reported to be related to dose received by the penile bulb. To minimise this, whilst preserving prostate dosimetry, we have developed a technique for I-125 seed brachytherapy using both stranded seeds and loose seeds delivered with a Mick applicator, and implanted via the sagittal plane on trans-rectal ultrasound.
  
  
  METHODS
  Post-implant dosimetry and potency rates were compared in 120 potent patients. In Group 1, 60 patients were treated using a conventional technique of seeds implanted in a modified-uniform distribution. From January 2005, a novel technique was developed using stranded seeds peripherally and centrally distributed loose seeds implanted via a Mick applicator (Group 2). The latter technique allows greater flexibility when implanting the seeds at the apex. Each patient was prescribed a minimum peripheral dose of 145 Gy. No patients received external beam radiotherapy or hormone treatment. There was no significant difference in age or pre-implant potency score (mean IIEF-5 score 22.4 vs. 22.6, p=0.074) between the two groups.
  
  
  RESULTS
  The new technique delivers lower penile bulb doses (D(25) as %mPD - Group 1: 61.2+/-35.7, Group 2: 29.7+/-16.0, p<0.0001; D(50) as %mPD - Group 1: 45.8+/-26.9, Group 2: 21.4+/-11.7, p<0.0001) whilst improving prostate dosimetry (D(90) - Group 1: 147 Gy+/-21.1, Group 2: 155 Gy+/-16.7, p=0.03). At 2 years, the potency rate was also improved: Group 1: 61.7%; Group 2: 83.3% (p=0.008).
  
  
  CONCLUSIONS
  In this study, the novel brachytherapy technique using both peripheral stranded seeds and central loose seeds delivered via a Mick applicator results in a lower penile bulb dose whilst improving prostate dosimetry, and may achieve higher potency rates.
authors.affiliation: St. Luke's Cancer Centre, The Royal Surrey County Hospital, Guildford, UK. jpnobes@gmail.com
authors.forename: Jenny P
authors.initials: JP
authors.lastname: Nobes
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Khaksar
authors.forename: Maria A
authors.initials: MA
authors.lastname: Hawkins
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Cunningham
authors.forename: Stephen E M
authors.initials: SE
authors.lastname: Langley
authors.forename: Robert W
authors.initials: RW
authors.lastname: Laing
mesh_terms: D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods*; D007172:Erectile Dysfunction / Q000209:etiology*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010413:Penis / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional
chemical_list: D007457:Iodine Radioisotopes