Korean J Med Phys.  2009 Jun;20(2):88-96.

Verification of Skin Dose in Tomotherapy Using the Developed Phantom for Image Based Radiation Treatment System

Affiliations
  • 1Department of Biomedical Engineering, The Catholic University of Korea, Seoul, Korea. suhsanta@catholic.ac.kr
  • 2 Research Institute of Biomedical Encinering, The Catholic University of Korea, Seoul, Korea.
  • 3Department of Radiation Oncology, St. Vincent's Hospital, The Catholic University of Korea, Seoul, Korea.
  • 4Department of Radiation Oncology, Konkuk University Medical Center, Seoul, Korea.
  • 5Department of Radiation Oncology, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
  • 6Department of Radiation Oncology, Ajou University Medical Center, Seoul, Korea.

Abstract

Radiation treatment for skin cancer has recently increased in tomotherapy. It was reported that required dose could be delivered with homogeneous dose distribution to the target without field matching using electron and photon beam. Therapeutic beam of tomotherapy, however, has several different physical characteristic and irradiation of helical beam is involved in the mechanically dynamic factors. Thus verification of skin dose is requisite using independent tools with additional verification method. Modified phantom for dose measurement was developed and skin dose verification was performed using inserted thermoluminescent dosimeters (TLDs) and GafChromic EBT films. As the homogeneous dose was delivered to the region including surface and 6 mm depth, measured dose using films showed about average 2% lower dose than calculated one in treatment planning system. Region indicating about 14% higher and lower absorbed dose was verified on measured dose distribution. Uniformity of dose distribution on films decreased as compared with that of calculated results. Dose variation affected by inhomogeneous material, Teflon, little showed. In regard to the measured dose and its distribution in tomotherapy, verification of skin dose through measurement is required before the radiation treatment for the target located at the curved surface or superficial depth.

Keyword

Skin dose; Helical tomotherapy; QA phantom; GafChromic EBT film; Thermoluminescent dosimeter (TLD)

MeSH Terms

Electrons
Polytetrafluoroethylene
Radiotherapy, Intensity-Modulated
Skin
Skin Neoplasms
Polytetrafluoroethylene
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