title: Accumulated dose to the rectum, measured using dose-volume histograms and dose-surface maps, is different from planned dose in all patients treated with radiotherapy for prostate cancer.
abstract: OBJECTIVE
  We sought to calculate accumulated dose (DA) to the rectum in patients treated with radiotherapy for prostate cancer. We were particularly interested in whether dose-surface maps (DSMs) provide additional information to dose-volume histograms (DVHs).
  
  
  METHODS
  Manual rectal contours were obtained for kilovoltage and daily megavoltage CT scans for 10 participants from the VoxTox study (380 scans). Daily delivered dose recalculation was performed using a ray-tracing algorithm. Delivered DVHs were summated to create accumulated DVHs. The rectum was considered as a cylinder, cut and unfolded to produce daily delivered DSMs; these were summated to produce accumulated DSMs.
  
  
  RESULTS
  Accumulated dose-volumes were different from planned in all participants. For one participant, all DA levels were higher and all volumes were larger than planned. For four participants, all DA levels were lower and all volumes were smaller than planned. For each of these four participants, ≥1% of pixels on the accumulated DSM received ≥5 Gy more than had been planned.
  
  
  CONCLUSIONS
  Differences between accumulated and planned dose-volumes were seen in all participants. DSMs were able to identify differences between DA and planned dose that could not be appreciated from the DVHs. Further work is needed to extract the dose data embedded in the DSMs. These will be correlated with toxicity as part of the VoxTox Programme.
  
  
  CONCLUSIONS
  DSMs are able to identify differences between DA and planned dose that cannot be appreciated from DVHs alone and should be incorporated into future studies investigating links between DA and toxicity.
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|2 Department of Oncology, University of Cambridge, Cambridge Biomedical Campus, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Scaife
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|3 Medical Physics Department, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Thomas
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|4 Department of Physics, University of Cambridge, Cavendish Laboratory, Cambridge, UK.
authors.forename: Karl
authors.initials: K
authors.lastname: Harrison
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|3 Medical Physics Department, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: Marina
authors.initials: M
authors.lastname: Romanchikova
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|5 Department of Engineering, University of Cambridge, Cambridge, UK.
authors.forename: Michael P F
authors.initials: MP
authors.lastname: Sutcliffe
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|6 Cambridge Clinical Trials Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: Julia R
authors.initials: JR
authors.lastname: Forman
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|2 Department of Oncology, University of Cambridge, Cambridge Biomedical Campus, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Amy M
authors.initials: AM
authors.lastname: Bates
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|2 Department of Oncology, University of Cambridge, Cambridge Biomedical Campus, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Raj
authors.initials: R
authors.lastname: Jena
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|4 Department of Physics, University of Cambridge, Cavendish Laboratory, Cambridge, UK.
authors.forename: M Andrew
authors.initials: MA
authors.lastname: Parker
authors.affiliation: 1 Cancer Research UK VoxTox Research Group, Department of Oncology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.|2 Department of Oncology, University of Cambridge, Cambridge Biomedical Campus, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Neil G
authors.initials: NG
authors.lastname: Burnet
mesh_terms: D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D012007:Rectum / Q000528:radiation effects*