Bulletin of Faculty of Health Sciences Okayama University Medical School
Published by Faculty of Health Sciences Okayama University Medical School

<Formerly known as>
岡山大学医療技術短期大学部紀要 (1巻-9巻)

Influence of the dose to the laryngeal cancer by the difference in radiation beam energy

青山 英樹 岡山大学医学部附属病院中央放射線部
中桐 義忠 岡山大学医学部保健学科放射線技術科学専攻
井上 光広 財団法人操風会岡山旭東病院放射線課
稲村 圭司 岡山大学医学部附属病院中央放射線部
田原 誠司 岡山大学医学部附属病院中央放射線部
宇野 弘文 岡山大学医学部附属病院中央放射線部
森岡 泰樹 岡山大学医学部附属病院中央放射線部
平木 祥夫 岡山大学医学部放射線医学講座
抄録
We investigated the usefulness of Gafchromic MD-55 film (Nuclear Associates, Inc.) for measuring the radiation doses on the radiotherapy of laryngeal cancers. Since larynx has thin wedge-shaped structure in anterior neck adjacent to airway, the radiation doses to the lesion may be diminished because of build-up and build-down. So, the dose has been measured with conventional measuring systems such as thermoluminescent dosimetry (TLD). However, it was not possible to evaluate the dose distribution correctly using TLD, because it is impossible to float a TLD chip in an air cavity. In this study, we employed Gafchromic MD-55 film as a dosimeter, for it can be set on the area of interest and with a measurability of dose range of 3 to 100 Gy, though it has no energy dependency. And this radiometer is composition near the soft tissue of the human body. The dose distributions to larynx were investigated with this film using neck phantom under each radiation beam energy of 4, 6 and 10 MV x-rays. Our neck phantom is made from acrylic resin and simulates a normal larynx on the basis of image information of computed tomography (CT). Moreover we observed secondary build-up and build-down curves in tissue in the vicinity of air cavities, especially at 10 MV x-rays. These findings suggest that patients with TI-T2 glottic cancers with anterior commissure invasion may receive more effective treatment with 4 MV x-rays rather than with 6 MV and 10 MV x-rays.
キーワード
Gafchromic MD-55-2 film
radiation dose
build-up
build-down
glottic cancer
ISSN
1345-0948
NCID
AA11403004