title: Shape analysis of the prostate: establishing imaging specifications for the design of a transurethral imaging device for prostate brachytherapy guidance.
abstract: OBJECTIVE
  To examine specific prostate and urethra dimensions and prostate shape to facilitate the design of a transurethral ultrasonographic imaging device.
  
  
  METHODS
  Computed tomographic (CT) data sets were retrospectively evaluated from 191 patients who underwent permanent prostate brachytherapy at our institution. The prostate, rectum, urethra, and bladder were each segmented with imaging software. Collected data and calculations included prostate volume at specific distances from the urethra and rectum, distances from seeds to urethra (SU), distances from seeds to rectum (SR), prostate length, and curvilinear prostatic urethra length.
  
  
  RESULTS
  The CT-based, postimplant mean prostate volume was 49cm(3) (range, 22-106cm(3)). Mean prostate length was 4.5cm (range, 3.1-6.0cm). The mean curvilinear length of the prostatic urethra was 4.5cm. The mean (standard deviation) prostatic urethra bend was 29.0° (12.2°). The mean surface distance from the prostate to the urethra was 2.9cm and from the prostate to the rectum w as 4.6cm (p<0.001, paired t test). The mean SU distance was 1.6cm, and the mean SR distance was 2.3cm (p<0.001). In the largest prostate, the mean SU distance was 3.9cm and the mean SR distance was 6.0cm.
  
  
  CONCLUSIONS
  A urethral imaging device for prostate brachytherapy and other minimally invasive prostate therapies should ideally have a 6-cm imaging field of view to image all the prostates in this series in a single image. The mean distance from the SU in permanent prostate brachytherapy is less than 70% of the mean SR distance.
authors: Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN.
authors: David R
authors: DR
authors: Holmes
authors: Department of Radiation Oncology, Mayo Clinic, Rochester, MN. Electronic address: davis.brian@mayo.edu.
authors: Brian J
authors: BJ
authors: Davis
authors: Department of Radiation Oncology, Billings Clinic, Billings, MT.
authors: Christopher C
authors: CC
authors: Goulet
authors: Department of Urology, Mayo Clinic, Rochester, MN.
authors: Torrence M
authors: TM
authors: Wilson
authors: Department of Urology, Mayo Clinic, Rochester, MN.
authors: Lance A
authors: LA
authors: Mynderse
authors: Department of Radiation Oncology, Mayo Clinic, Rochester, MN.
authors: Keith M
authors: KM
authors: Furutani
authors: Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN.
authors: Jon J
authors: JJ
authors: Camp
authors: Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN.
authors: Richard A
authors: RA
authors: Robb
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D008297:Male; D009929:Organ Size; D011467:Prostate / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012007:Rectum / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D018084:Ultrasonography, Interventional / Q000295:instrumentation*; D014521:Urethra / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D001743:Urinary Bladder / Q000033:anatomy & histology / Q000000981:diagnostic imaging
keywords: Brachytherapy; Computed tomography; Prostate; Prostatic neoplasms; Radiotherapy; Ultrasonography; Urethra