title: Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for 125I and 103Pd brachytherapy sources relative to 60Co.
abstract: OBJECTIVE
  To determine the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters (TLD-100) for (125)I and (103)Pd brachytherapy sources relative to (60)Co.
  
  
  METHODS
  LiF:Mg,Ti TLDs were irradiated with low-energy brachytherapy sources and with a (60)Co teletherapy source. The brachytherapy sources measured were the Best 2301 (125)I seed, the OncoSeed 6711 (125)I seed, and the Best 2335 (103)Pd seed. The TLD light output per measured air-kerma strength was determined for the brachytherapy source irradiations, and the TLD light output per air kerma was determined for the (60)Co irradiations. Monte Carlo (MC) simulations were used to calculate the dose-to-TLD rate per air-kerma strength for the brachytherapy source irradiations and the dose to TLD per air kerma for the (60)Co irradiations. The measured and MC-calculated results for all irradiations were used to determine the TLD intrinsic energy dependence for (125)I and (103)Pd relative to (60)Co.
  
  
  RESULTS
  The relative TLD intrinsic energy dependences (relative to (60)Co) and associated uncertainties (k = 1) were determined to be 0.883 ± 1.3%, 0.870 ± 1.4%, and 0.871 ± 1.5% for the Best 2301 seed, OncoSeed 6711 seed, and Best 2335 seed, respectively.
  
  
  CONCLUSIONS
  The intrinsic energy dependence of TLD-100 is dependent on photon energy, exhibiting changes of 13%-15% for (125)I and (103)Pd sources relative to (60)Co. TLD measurements of absolute dose around (125)I and (103)Pd brachytherapy sources should explicitly account for the relative TLD intrinsic energy dependence in order to improve dosimetric accuracy.
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705.
authors.forename: J L
authors.initials: JL
authors.lastname: Reed
authors.affiliation: Department of Radiation Oncology, UP Health System Marquette, 580 West College Avenue, Marquette, Michigan 49855.
authors.forename: B E
authors.initials: BE
authors.lastname: Rasmussen
authors.affiliation: Department of Medical Physics, McGill University Health Centre, Montreal General Hospital (L5-112), 1650 Cedar Avenue, Montreal, Quebec H3G 1A4, Canada.
authors.forename: S D
authors.initials: SD
authors.lastname: Davis
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705.
authors.forename: J A
authors.initials: JA
authors.lastname: Micka
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705.
authors.forename: W S
authors.initials: WS
authors.lastname: Culberson
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705.
authors.forename: L A
authors.initials: LA
authors.lastname: DeWerd
mesh_terms: D055592:Biophysical Phenomena; D001918:Brachytherapy; D003037:Cobalt Radioisotopes / Q000627:therapeutic use; D003198:Computer Simulation; D005459:Fluorides; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D018020:Lithium Compounds; D008274:Magnesium; D009010:Monte Carlo Method; D010165:Palladium / Q000627:therapeutic use; D011868:Radioisotopes / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D014025:Titanium
chemical_list: D003037:Cobalt Radioisotopes; D007457:Iodine Radioisotopes; D018020:Lithium Compounds; D011868:Radioisotopes; C027651:lithium fluoride; D010165:Palladium; D014025:Titanium; D008274:Magnesium; D005459:Fluorides