title: Assessment of large single-fraction, low-energy X-ray dose with radiochromic film.
abstract: OBJECTIVE
  To investigate the accuracy of in vivo dosimetry using radiochromic film for large single-fraction, low-energy irradiations.
  
  
  METHODS
  Gafchromic MD-55-2 radiochromic film and LiF thermoluminescent dosimeters (TLDs) were placed in vivo on 25 patients to ascertain their effectiveness for assessment of dose. All patients received 10 Gy single fractions at energies ranging from 100 kVp (half-value layer [HVL] = 3.5 mm Al) up to 250 kVp (HVL = 2.3 mm Cu). Effects of small air gaps were also investigated using LiF TLDs and radiochromic film.
  
  
  RESULTS
  Radiochromic film adequately measured applied dose for 25 patients in vivo with a standard deviation of 5.5% from prescribed dose. LiF TLDs recorded a standard deviation of 4.1% from measured to applied dose. Small air gaps which can be created under the film or TLDs during in vivo dosimetry were shown to have a measurable but minimal effect on results for gaps less than 5 mm.
  
  
  CONCLUSIONS
  Gafchromic film has adequately measured applied dose in vivo at low energy for large 10 Gy single-fraction irradiation.
authors.affiliation: City University of Hong Kong, Department of Physics and Materials Science, Kowloon Tong, Hong Kong.
authors.forename: M J
authors.initials: MJ
authors.lastname: Butson
authors.forename: T
authors.initials: T
authors.lastname: Cheung
authors.forename: P K
authors.initials: PK
authors.lastname: Yu
authors.forename: P E
authors.initials: PE
authors.lastname: Metcalfe
mesh_terms: D005459:Fluorides; D006801:Humans; D018020:Lithium Compounds; D055585:Physical Phenomena; D010825:Physics; D011874:Radiometry / Q000295:instrumentation / Q000379:methods; D011879:Radiotherapy Dosage; D014962:X-Ray Film
chemical_list: D018020:Lithium Compounds; C027651:lithium fluoride; D005459:Fluorides