非侵襲的呼吸同期照射に向けた腹壁運動と肺腫瘍運動との相関解析  [in Japanese] CORRELATIVE ANALYSIS OF ABDOMINAL MOTION WITH LUNG TUMOR MOTION FOR NON-INVASIVE RESPIRATORY GATED RADIOTHERAPY  [in Japanese]

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Author(s)

    • 中村 光宏 NAKAMURA Mitsuhiro
    • 京都大学大学院医学研究科放射線腫瘍学・画像応用治療学 Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine
    • 平岡 眞寛 HIRAOKA Masahiro
    • 京都大学大学院医学研究科放射線腫瘍学・画像応用治療学 Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine
    • 成田 雄一郎 NARITA Yuichiro
    • 京都大学大学院医学研究科放射線腫瘍学・画像応用治療学 Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine
    • 松尾 幸憲 MATSUO Yukinori
    • 京都大学大学院医学研究科放射線腫瘍学・画像応用治療学 Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine
    • 楢林 正流 NARABAYASHI Masaru
    • 京都大学大学院医学研究科放射線腫瘍学・画像応用治療学 Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine
    • 澤田 晃 SAWADA Akira
    • 京都大学大学院医学研究科放射線腫瘍学・画像応用治療学 Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine
    • 溝脇 尚志 MIZOWAKI Takashi
    • 京都大学大学院医学研究科放射線腫瘍学・画像応用治療学 Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine

Abstract

【目的】本研究の目的は,商用の呼吸同期照射システムで得た背腹方向の腹壁変位量とX線シミュレーターで観測した頭尾方向の肺腫瘍変位量の位相相関性を評価し,腹壁変位量が予測した腫瘍位置と測定した腫瘍位置のずれ量(以下,腫瘍位置ずれ量)を算出することであった.【方法】2006年12月から2008年 3 月までの間に,当院で肺定位放射線治療を施行した11症例を対象とした.そのうち 6 症例は倫理審査委員会の承認の下,3 日間にわたって測定を行った.Real-time Positioning Managementシステム(Varian Medical Systems, Inc., Palo Alto, CA)で計測した腹壁変位量の画面と肺腫瘍変位量が投影されたX線シミュレーター(Acuity; Varian Medical Systems, Inc.)の画面を並列に表示し,自由呼吸下で60秒間計測した.取得した並列画像に対して画像処理を行った後,テンプレートマッチングで肺腫瘍の位置を検出した.腹壁変位量と肺腫瘍変位量から位相相関性を評価した.また,位相ずれを補正した回帰直線を用いて,腹壁運動が予測した肺腫瘍位置を求め,これと測定した肺腫瘍位置を比較することで,腫瘍位置ずれ量を算出した.【結果】相関係数の絶対値は0.89から0.97の範囲内にあり,これらの日々の変動も安定していた.腹壁変位量と肺腫瘍変位量の位相ずれが原因で生じるヒステリシス曲線を描く症例も存在した.腫瘍位置ずれ量の平均値は最大で1.78mmであった.【結論】多くの症例で,腹壁変位量と肺腫瘍変位量との位相相関性は良好であったが,腹壁変位量が予測した肺腫瘍位置と測定した肺腫瘍位置の間にずれが生じていた.

Purpose: The purposes of this study were to assess the correlation between lung tumor motion and the abdominal motion, and to estimate the position mismatch as the difference between the abdominal motion trace used to the predicted lung tumor position and the measured lung tumor position.<br>Methods and Materials: Eleven patients who underwent stereotactic body radiotherapy between December 2006 and March 2008 were included in this study. Of all the patients, 6 were studied over 3 days under an internal review board approved protocol. Breathing synchronized fluoroscopy was performed under free breathing. Measurements of the anterior-posterior abdominal skin surface displacement by the Real-time Positioning Management System (Varian Medical Systems, Inc., Palo Alto, CA) were correlated to simultaneously acquired X-ray fluoroscopy (Acuity; Varian Medical Systems, Inc.) measurements of superior-inferior tumor displacement. The lung tumor motion was analytically detected by a template matching algorithm after image processing. To evaluate the tumor-abdominal motion phase relationship, a cross-correlation was calculated of the time-synchronized tumor motion and the abdominal motion. By comparing the predicted lung tumor position in which phase difference was corrected to the measured lung tumor position, the position mismatch was computed.<br>Results: The correlation coefficients between the lung tumor motion and abdominal motion ranged 0.89 from 0.97 and more reproducible from day to day. A hysteresis curve was observed due to phase difference between the lung tumor motion and abdominal motion. The average of the position mismatch was up to 1.78 mm.<br>Conclusion: Even if the correlation coefficients between the abdominal motion and the tumor motion were high for most cases, there were some differences between the predicted lung tumor position and the measured lung tumor position.

Journal

  • The Journal of JASTRO

    The Journal of JASTRO 20(3), 119-125, 2008

    Japanese Society for Therapeutic Radiology and Oncology

Codes

  • NII Article ID (NAID)
    130004497140
  • Text Lang
    JPN
  • ISSN
    1040-9564
  • Data Source
    J-STAGE 
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