title: Wax boluses and accuracy of EBT and RTQA radiochromic film detectors in radiotherapy with the JINR Phasotron proton beam.
abstract: OBJECTIVE
  To present the results obtained using radiochromic films EBT and RTQA 1010P for the reconstruction the dose distributions for targets irradiated by proton beam and modified by wax boluses.
  
  
  BACKGROUND
  In Medico-Technical Complex at the Joint Institute for Nuclear Research in Dubna implemented technology of wax boluses.
  
  
  METHODS
  Wax boluses are easier to make and they give better dose distributions than boluses made from modeling clay previously used at our center. We irradiated two imaginary targets, one shaped as a cylinder and the other one as two cuboids. The evaluated calibration curve was used for calculation of the dose distributions measured by the EBT and RTQA radiochromic film. In both cases, the measured dose distributions were compared to the dose distributions calculated by the treatment planning system (TPS). We also compared dose distributions using three different conformity indices at a 95% isodose.
  
  
  RESULTS
  Better target coverage and better compliance of measurements (semiconductor detectors and radiochromic films) with calculated doses was obtained for cylindrical target than for cuboidal target. The 95% isodose covered well the tumor for both target shapes, while for cuboidal target larger volume around the target received therapeutic dose, due to the complicated target shape. The use wax boluses provided to be effective tool in modifying proton beam to achieve appropriate shape of isodose distribution.
  
  
  CONCLUSIONS
  EBT film yielded the best visual matching. Both EBT and RTQA films confirmed good conformity between calculated and measured doses, thus confirming that wax boluses used to modify the proton beam resulted in good dose distributions.
authors.affiliation: Department of Medical Physics, Greater Poland Cancer Centre, 15 Garbary Street, 61-688 Poznan, Poland ; Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 6 Joliot-Curie Street, 141980 Dubna, Moscow Region, Russia.
authors.forename: Dorota Maria
authors.initials: DM
authors.lastname: Borowicz
authors.affiliation: Department of Medical Physics, Greater Poland Cancer Centre, 15 Garbary Street, 61-688 Poznan, Poland ; Electroradiology Department, University of Medical Sciences, 15 Garbary Street, 61-688 Poznan, Poland.
authors.forename: Julian
authors.initials: J
authors.lastname: Malicki
authors.affiliation: Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 6 Joliot-Curie Street, 141980 Dubna, Moscow Region, Russia.
authors.forename: Gennady
authors.initials: G
authors.lastname: Mytsin
authors.affiliation: Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 6 Joliot-Curie Street, 141980 Dubna, Moscow Region, Russia.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Shipulin
keywords: Dosimetry; Proton therapy; Radiochromic films