title: The Effect of Dose and Quality Assurance in Early Prostate Cancer Treated with Low Dose Rate Brachytherapy as Monotherapy.
abstract: To examine the relationship between post-implant computed tomography dosimetry and long-term prostate-specific antigen relapse-free survival in patients treated with iodine 125 (I-125) low dose rate prostate brachytherapy as monotherapy and, second, to audit recent practice against Royal College of Radiologists' (RCR) guidelines after the re-introduction of post-implant dosimetry for all patients in our centre.
  
  
  
  Between March 1995 and September 2007, 2157 consecutive patients with localised prostate cancer underwent I-125 permanent prostate brachytherapy as monotherapy in a single UK centre. All patients were transrectal ultrasound planned delivering a 145 Gy (TG 43) minimum peripheral dose. None received supplemental external beam radiotherapy. Post-implant computed tomography-based dosimetry was undertaken between 4 and 6 weeks after treatment and was available for 711 (33%). Outcomes were analysed in terms of the relationship of D90 to prostate-specific antigen relapse-free survival (nadir 2+ definition) and all patients had a minimum follow-up of 5 years. For contemporary patients from 2011, quality metrics from post-implant computed tomography as defined by RCR guidelines are presented.
  
  
  
  A mean D90 of 138.7 Gy (standard deviation 24.7) was achieved for the historic cohort. Biochemical control at 10 years was 76% in patients with D90 > 140 Gy and 68% in those with D90 < 140 Gy (P < 0.01). In current practice, over the last 3 years the mean (standard deviation) D90 has increased from 154 (15.3) Gy in 2011 to 164 (13.5) Gy in 2013. Similarly, an increase in the mean (standard deviation) V100 from 92 (4.4) to 95 (3.2) % is noted over time. No difference between clinicians was noted.
  
  
  
  D90 values of less than 140 Gy continue to be predictive of increased risk of recurrence of prostate cancer across risk groups with longer follow-up. Quality assurance can be used to ensure improved and consistent implant quality in a team with multiple clinicians.
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK; University of Leeds, Leeds, UK. Electronic address: A.Henry@leeds.ac.uk.
authors: A M
authors: AM
authors: Henry
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK.
authors: S L
authors: SL
authors: Rodda
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK.
authors: M
authors: M
authors: Mason
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK.
authors: H
authors: H
authors: Musunuru
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK.
authors: B
authors: B
authors: Al-Qaisieh
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK.
authors: P
authors: P
authors: Bownes
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK.
authors: J
authors: J
authors: Smith
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK.
authors: K
authors: K
authors: Franks
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK.
authors: B
authors: B
authors: Carey
authors: Leeds Cancer Centre, St James's University Hospital, Leeds, UK.
authors: D
authors: D
authors: Bottomley
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011785:Quality Assurance, Health Care; D011879:Radiotherapy Dosage; D014057:Tomography, X-Ray Computed
chemical_list: D007457:Iodine Radioisotopes; D017430:Prostate-Specific Antigen
keywords: Brachytherapy; dosimetry; outcomes; prostate cancer; quality assurance