title: Image-guided intensity-modulated radiotherapy of prostate cancer: Analysis of interfractional errors and acute toxicity.
abstract: OBJECTIVE
  The aim of the study was to estimate interfractional deviations in patient and prostate position, the impact of the frequency of online verification on the treatment margins, and to assess acute radiation reactions of high-dose external beam image-guided intensity-modulated radiotherapy (IG-IMRT) of localized prostate cancer.
  
  
  METHODS
  IG-IMRT was performed by daily online verification of implanted fiducial prostate markers using a megavoltage electronic portal imaging device (EPID). A total of 1011 image-guided treatment fractions from 23 consecutive unselected prostate cancer patients were analyzed. The median total dose was 79.2 Gy (range 77.4-81.0 Gy). Acute radiation reactions were assessed weekly during radiotherapy using the Common Terminology Criteria for Adverse Events (CTCAE) v.4.03.
  
  
  RESULTS
  A relevant combined patient set-up and prostate motion population random error of 4-5 mm was observed. Compared to daily IGRT, image guidance every other day required an expansion of the CTV-PTV (clinical target volume-planning target volume) margin of 8.1, 6.6, and 4.1 mm in the longitudinal, vertical, and lateral directions, thereby, increasing the PTV by approximately 30-40 %. No grade 3 or 4 acute radiation reactions were observed with daily IG-IMRT.
  
  
  CONCLUSIONS
  A high dose with surprisingly low acute toxicity can be applied with daily IG-IMRT using implanted fiducial prostate markers. Daily image guidance is clearly superior to image guidance every other fraction concerning adequate target coverage with minimal margins.
authors.affiliation: Department of Radiation Oncology, Saad Specialist Hospital, 31952, Al Khobar, Saudi Arabia. volker.rudat@gmail.com.
authors.forename: Volker
authors.initials: V
authors.lastname: Rudat
authors.affiliation: Department of Radiation Oncology, Saad Specialist Hospital, 31952, Al Khobar, Saudi Arabia.
authors.forename: A
authors.initials: A
authors.lastname: Nour
authors.affiliation: Department of Radiation Oncology, Saad Specialist Hospital, 31952, Al Khobar, Saudi Arabia.
authors.forename: M
authors.initials: M
authors.lastname: Hammoud
authors.affiliation: Department of Radiation Oncology, Saad Specialist Hospital, 31952, Al Khobar, Saudi Arabia.
authors.forename: A
authors.initials: A
authors.lastname: Alaradi
authors.affiliation: Department of Radiation Oncology, Saad Specialist Hospital, 31952, Al Khobar, Saudi Arabia.
authors.forename: A
authors.initials: A
authors.lastname: Mohammed
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D019583:Dose Fractionation, Radiation; D057918:Fiducial Markers; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061106:Radiotherapy Setup Errors; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: Fiducial markers; Image-guided radiotherapy; Intensity-modulated radiotherapy; Planning target volume; Prostate neoplasms