The absorbed dose evaluation of radiation therapy of early glottic cancer by the difference in X-ray energy: Investigation with a film type dosimeter

Hideki Aoyama, Yoshitada Nakagiri, Keiji Inamura, Seiji Tahara, Hirofumi Uno, Yoshiharu Azuma, Yoshio Hiraki

Research output: Contribution to journalArticle

Abstract

Purpose: Radiation therapy is an established method for treatment of early glottic cancers. Since the larynx is a thin wedge-shaped structure in the anterior neck adjacent to the airway, the absorbed doses to the lesion may be diminished because of build-up and build-down. The dose has been measured with conventional measuring systems such as thermoluminescent dosimetry (TLD). In this study, we employed Gafchromic MD-55-2 film (Nuclear Associates, Inc) as a dosimeter, for it can be set on the area of interest and with a measurability of a dose range of 3 to 100 Gy, and this radiometer material is similar in soft tissue of the human body. The dose distributions to the larynx were investigated with this film using a neck phantom under radiation beam energies of 4, 6 and 10 MV X-rays. Material and Method: The neck phantom was irradiated using 4, 6 and 10 MV X-rays, each with right and left lateral parallel-opposed fields, total radiation dose of 20 Gy, field size of 6 cm × 6 cm and 15 degrees wedge filter. Result: As a result, we observed secondary build-up and build-down curves in tissue in the vicinity of air cavities, especially at 10 MV X-rays. In the anterior commissure · center of glottic region, the absorbed doses decreasing rates of absorbed dose to 20 Gy with 4, 6, and 10 MV X-rays were 6.15% · 7.35%, 8.90% · 9.45% and 15.6% · 12.7% respectively. Conclusion: These findings suggest that patients with early glottic cancer with anterior commissure invasion may receive more effective treatment with 4 MV X-rays rather than with 6 MV or 10 MV X-rays.

Original languageEnglish
Pages (from-to)239-245
Number of pages7
JournalJournal of JASTRO
Volume14
Issue number4
Publication statusPublished - Dec 2002

Keywords

  • Build-down
  • Build-up
  • Early glottic cancer
  • Gafchromic MD-55-2 film

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Oncology

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    Aoyama, H., Nakagiri, Y., Inamura, K., Tahara, S., Uno, H., Azuma, Y., & Hiraki, Y. (2002). The absorbed dose evaluation of radiation therapy of early glottic cancer by the difference in X-ray energy: Investigation with a film type dosimeter. Journal of JASTRO, 14(4), 239-245.