title: Values of biologically equivalent doses in healthy tissues: comparison of PDR and HDR brachytherapy techniques.
abstract: OBJECTIVE
  The aim of this work was to compare the values of doses measured in healthy tissues in chosen pulsed-dose-rate (PDR) brachytherapy (PDRBT) and high-dose-rate (HDR) brachytherapy (HDRBT) fractionation schemas.
  
  
  METHODS
  Fifty-one patients treated with PDRBT were qualified for calculations. This group included patients with head and neck cancer, brain tumor, breast cancer, sarcoma, penile cancer, and rectal cancer. The doses were calculated in chosen points in surrounded organs at risk (OaR). The biologically equivalent dose (BED) formula was used to compare doses in PDRBT and HDRBT.
  
  
  RESULTS
  One ascertained that in biologically equivalent (to PDR) HDRBT, the increase of fractional dose from 4 to 10 Gy caused the necessity to decrease the total dose in treatment target (p<0.001). The use of HDR instead of PDR essentially caused lower physical and biologic doses in examined OaR. In many examined critical points in OaR where BED in the treatment area was the same, one ascertained the decrease of total physical HDR dose according to the growth of the fractional dose. Similar dependences were observed for BED.
  
  
  CONCLUSIONS
  The use of biologically equivalent HDRBT instead of PDRBT caused the decrease of physical doses in the treatment target and the decrease of physical doses and BEDs in OaR. Prolongation of intervals between pulses in PDRBT was connected with lower values of BED doses in healthy tissues.
authors.affiliation: Brachytherapy Department, Greater Poland Cancer Center, Poznań, Poland. janusz.skowronek@wco.pl
authors.forename: Janusz
authors.initials: J
authors.lastname: Skowronek
authors.forename: Julian
authors.initials: J
authors.lastname: Malicki
authors.forename: Tomasz
authors.initials: T
authors.lastname: Piotrowski
mesh_terms: D000328:Adult; D001918:Brachytherapy / Q000379:methods*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012062:Relative Biological Effectiveness; D016896:Treatment Outcome; D055815:Young Adult