Verification of calculated skin doses in postmastectomy helical tomotherapy

Shima Ito, Brent Parker, Renee Levine, Mary Ella Sanders, Jonas Fontenot, John Gibbons, Kenneth Hogstrom

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Purpose: To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). Methods and Materials: 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%.

Original languageEnglish (US)
Pages (from-to)584-591
Number of pages8
JournalInternational Journal of Radiation Oncology Biology Physics
Volume81
Issue number2
DOIs
StatePublished - Oct 1 2011
Externally publishedYes

Fingerprint

Intensity-Modulated Radiotherapy
dosimeters
dosage
Skin
standard deviation
scars
Cicatrix
Mastectomy
Therapeutics
Radiation Dosimeters
Radiotherapy
planning
radiation therapy

Keywords

  • Chest wall
  • Helical tomotherapy
  • in vivo dosimetry
  • PMRT
  • Skin dose

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Radiation
  • Cancer Research

Cite this

Verification of calculated skin doses in postmastectomy helical tomotherapy. / Ito, Shima; Parker, Brent; Levine, Renee; Sanders, Mary Ella; Fontenot, Jonas; Gibbons, John; Hogstrom, Kenneth.

In: International Journal of Radiation Oncology Biology Physics, Vol. 81, No. 2, 01.10.2011, p. 584-591.

Research output: Contribution to journalArticle

Ito, Shima ; Parker, Brent ; Levine, Renee ; Sanders, Mary Ella ; Fontenot, Jonas ; Gibbons, John ; Hogstrom, Kenneth. / Verification of calculated skin doses in postmastectomy helical tomotherapy. In: International Journal of Radiation Oncology Biology Physics. 2011 ; Vol. 81, No. 2. pp. 584-591.
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abstract = "Purpose: To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). Methods and Materials: 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{\%}.",
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