title: Neurovascular Bundle Infiltration Can Explain Local Relapses Using Conformal Radiotherapy of Prostate Cancer.
abstract: To quantify the impact of decreased margins for two treatment techniques, three-dimensional conformal radiotherapy (3D-CRT) and volumetric-modulated arc therapy (VMAT), on local control in curative treatment of prostate cancer.
  
  
  
  The planning target volume (PTV) margins were decreased in steps of 1 mm from 10 to 1 mm. Treatment plans using 3D-CRT and VMAT technique were produced for all margin sizes and the dose to the neuro vascular bundles (NVB), that was not included in the PTV, was investigated.
  
  
  
  Due to the more conformal dose delivery using VMAT, the dose to the NVB decreased more rapidly by VMAT compared to the 3D-CRT plans. The dose difference was significant for margins from 1-7 mm.
  
  
  
  One should be very cautious before clinical routines are changed, bearing in mind whether the change means more conformal treatment technique, smaller margins or target segmentation in different imaging modalities.
authors.affiliation: Section of Medical Physics, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden andreas.johansson@igp.uu.se.|Centre for Clinical Research Sörmland, Uppsala University, Eskilstuna, Sweden.
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Johansson
authors.affiliation: Department of Oncology, Örebro University Hospital, Örebro, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Lennernäs
authors.affiliation: Section of Medical Physics, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Isacsson
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D060787:Neoplasm Grading; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000209:etiology; D009389:Neovascularization, Pathologic / Q000209:etiology*; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*
keywords: 3D-CRT; Prostate cancer; VMAT; local relapse; radiotherapy