title: Prostate cancer treated with image-guided helical TomoTherapy® and image-guided LINAC-IMRT : Correlation between high-dose bladder volume, margin reduction, and genitourinary toxicity.
abstract: BACKGROUND
  We compared different image-guidance (IG) strategies for prostate cancer with high-precision IG intensity-modulated radiation therapy (IMRT) using TomoTherapy® (Accuray Inc., Madison, WI, USA) and linear accelerator (LINAC)-IMRT and their impact on planning target volume (PTV) margin reduction. Follow-up data showed reduced bladder toxicity in TomoTherapy patients compared to LINAC-IMRT. The purpose of this study was to quantify whether the treatment delivery technique and decreased margins affect reductions in bladder toxicity.
  
  
  METHODS
  Setup corrections from 30 patients treated with helical TomoTherapy and 30 treated with a LINAC were analyzed. These data were used to simulate three IG protocols based on setup error correction and a limited number of imaging sessions. For all patients, gastrointestinal (GI) and genitourinary (GU) toxicity was documented and correlated with the treatment delivery technique.
  
  
  RESULTS
  For fiducial marker (FM)-based RT, a margin reduction of up to 3.1, 3.0, and 4.8 mm in the left-right (LR), superior-inferior (SI), and anterior-posterior (AP) directions, respectively, could be achieved with calculation of a setup correction from the first three fractions and IG every second day. Although the bladder volume was treated with mean doses of 35 Gy in the TomoTherapy group vs. 22 Gy in the LINAC group, we observed less GU toxicity after TomoTherapy.
  
  
  CONCLUSIONS
  Intraprostate FMs allow for small safety margins, help decrease imaging frequency after setup correction, and minimize the dose to bladder and rectum, resulting in lower GU toxicity. In addition, IMRT delivered with TomoTherapy helps to avoid hotspots in the bladder neck, a critical anatomic structure associated with post-RT urinary toxicity.
authors.affiliation: Department of Radiation Oncology, University Hospital Jena, Friedrich-Schiller-University Jena, Bachstrasse 18, 07743, Jena, Germany. Sonia.Drozdz@med.uni-jena.de.
authors.forename: Sonia
authors.initials: S
authors.lastname: Drozdz
authors.affiliation: Department of Radiation Oncology, Section of Medical Physics, University Hospital Jena, Friedrich-Schiller-University Jena, Bachstrasse 18, 07743, Jena, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schwedas
authors.affiliation: Department of Radiation Oncology, Section of Medical Physics, University Hospital Jena, Friedrich-Schiller-University Jena, Bachstrasse 18, 07743, Jena, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Salz
authors.affiliation: Department of Urology, University Hospital Jena, Friedrich-Schiller-University Jena, Lessingstrasse 1, 07743, Jena, Germany.
authors.forename: Susan
authors.initials: S
authors.lastname: Foller
authors.affiliation: Department of Radiation Oncology, University Hospital Jena, Friedrich-Schiller-University Jena, Bachstrasse 18, 07743, Jena, Germany.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Wendt
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000532:radiotherapy*; D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy; D041981:Gastrointestinal Tract / Q000528:radiation effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011471:Prostatic Neoplasms / Q000473:pathology / Q000628:therapy*; D011832:Radiation Injuries / Q000209:etiology*; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D013223:Statistics as Topic; D025321:Surgery, Computer-Assisted / Q000379:methods*; D001743:Urinary Bladder / Q000528:radiation effects*; D014566:Urogenital System / Q000528:radiation effects*
keywords: Adverse effects; Fiducial markers; Margins; Organs at risk; Tomotherapy