title: Verification of calculated skin doses in postmastectomy helical tomotherapy.
abstract: OBJECTIVE
  To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT).
  
  
  METHODS
  In vivo thermoluminescent dosimeters (TLDs) were used to measure the skin dose at multiple points in each of 14 patients throughout the course of treatment on a TomoTherapy Hi·Art II system, for a total of 420 TLD measurements. Five patients were evaluated near the location of the mastectomy scar, whereas 9 patients were evaluated throughout the treatment volume. The measured dose at each location was compared with calculations from the treatment planning system.
  
  
  RESULTS
  The mean difference and standard error of the mean difference between measurement and calculation for the scar measurements was -1.8% ± 0.2% (standard deviation [SD], 4.3%; range, -11.1% to 10.6%). The mean difference and standard error of the mean difference between measurement and calculation for measurements throughout the treatment volume was -3.0% ± 0.4% (SD, 4.7%; range, -18.4% to 12.6%). The mean difference and standard error of the mean difference between measurement and calculation for all measurements was -2.1% ± 0.2% (standard deviation, 4.5%: range, -18.4% to 12.6%). The mean difference between measured and calculated TLD doses was statistically significant at two standard deviations of the mean, but was not clinically significant (i.e., was <5%). However, 23% of the measured TLD doses differed from the calculated TLD doses by more than 5%.
  
  
  CONCLUSIONS
  The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%.
authors.affiliation: Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, Baton Rouge, LA, USA.
authors.forename: Shima
authors.initials: S
authors.lastname: Ito
authors.forename: Brent C
authors.initials: BC
authors.lastname: Parker
authors.forename: Renee
authors.initials: R
authors.lastname: Levine
authors.forename: Mary Ella
authors.initials: ME
authors.lastname: Sanders
authors.forename: Jonas
authors.initials: J
authors.lastname: Fontenot
authors.forename: John
authors.initials: J
authors.lastname: Gibbons
authors.forename: Kenneth
authors.initials: K
authors.lastname: Hogstrom
mesh_terms: D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D002921:Cicatrix; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging; D008168:Lung / Q000000981:diagnostic imaging; D008408:Mastectomy; D008875:Middle Aged; D016011:Normal Distribution; D058958:Organs at Risk / Q000000981:diagnostic imaging; D011184:Postoperative Period; D011829:Radiation Dosage; D011859:Radiography; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012867:Skin / Q000528:radiation effects*; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation / Q000379:methods*; D035441:Thoracic Wall / Q000528:radiation effects*