title: Interstitial biodegradable balloon for reduced rectal dose during prostate radiotherapy: results of a virtual planning investigation based on the pre- and post-implant imaging data of an international multicenter study.
abstract: OBJECTIVE
  To evaluate dose reduction caused by the implantation of an interstitial inflatable and biodegradable balloon device aiming to achieve lower rectal doses with virtual 3D conformal external beam radiation treatment.
  
  
  METHODS
  An inflatable balloon device was placed, interstitially and under transrectal ultrasound guidance, into the rectal-prostate interspace prior treatment initiation of 26 patients with localized prostate cancer, who elected to be treated with radiotherapy (3D CRT or IMRT). The pre- and post-implant CT imaging data of twenty two patients were collected (44 images) for the purpose of the 3D conformal virtual planning presented herein.
  
  
  RESULTS
  The dorsal prostate-ventral rectal wall separation resulted in an average reduction of the rectal V70% by 55.3% (± 16.8%), V80% by 64.0% (± 17.7%), V90% by 72.0% (± 17.1%), and V100% by 82.3% (± 24.1%). In parallel, rectal D2 ml and D0.1 ml were reduced by 15.8% (± 11.4%) and 3.9% (± 6.4%), respectively.
  
  
  CONCLUSIONS
  Insertion of the biodegradable balloon into the prostate-rectum interspace is similar to other published invasive procedures. In this virtual dose distribution analysis, the balloon insertion resulted in a remarkable reduction of rectal volume exposed to high radiation doses. This effect has the potential to keep the rectal dose lower especially when higher than usual prostate dose escalation protocols or hypo-fractionated regimes are used. Further prospective clinical investigations on larger cohorts and more conformal radiation techniques will be necessary to define the clinical advantage of the biodegradable interstitial tissue separation device.
authors.affiliation: Department of Interdisciplinary Brachytherapy, University of Lübeck, Germany.
authors.forename: Corinna
authors.initials: C
authors.lastname: Melchert
authors.forename: Eliahu
authors.initials: E
authors.lastname: Gez
authors.forename: Günther
authors.initials: G
authors.lastname: Bohlen
authors.forename: Giovanni
authors.initials: G
authors.lastname: Scarzello
authors.forename: Isaac
authors.initials: I
authors.lastname: Koziol
authors.forename: Mitchell
authors.initials: M
authors.lastname: Anscher
authors.forename: Shmuel
authors.initials: S
authors.lastname: Cytron
authors.forename: Adrian
authors.initials: A
authors.lastname: Paz
authors.forename: Taryn
authors.initials: T
authors.lastname: Torre
authors.forename: Mathew
authors.initials: M
authors.lastname: Bassignani
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Dal Moro
authors.forename: Dieter
authors.initials: D
authors.lastname: Jocham
authors.forename: Rami Ben
authors.initials: RB
authors.lastname: Yosef
authors.forename: Benjamin W
authors.initials: BW
authors.lastname: Corn
authors.forename: György
authors.initials: G
authors.lastname: Kovács
mesh_terms: D006801:Humans; D008297:Male; D058958:Organs at Risk / Q000528:radiation effects*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000295:instrumentation* / Q000379:methods; D012007:Rectum / Q000528:radiation effects*; D014057:Tomography, X-Ray Computed