螺旋刀靜態式照野寬度與調變因子參數設定對放射治療攝護腺癌影響：侖道假體研究

本研究目的在探討螺旋刀（tomotherapy）執行電腦治療計劃優化演算，設定不同靜態式照野寬度（field width, FW）與不同調變因子（modulation factor, MF）參數設定，對於放射治療攝護腺癌各危急器官（organs at risk, OAR）劑量與治療時間的影響。依據臨床病例攝護腺癌之腫瘤位置，假想規劃計劃靶體積（PTV）與危急器官在侖道假體（Rando phantom）電腦斷層影像上。共設計42組螺旋刀之電腦治療計劃，使用相同的參數設定（重要性與嚴厲性），並搭配不同靜態式照野寬度（1.0 cm、2.5 cm）搭配不同調變因子數值（1.0至5.0，每數值間隔0.2）電腦治療計劃優化演算設定組合。研究結果顯示42個電腦治療計劃中，PTV接受到100%處方劑量包覆率皆達到95%以上的標準，表示不同靜態式照野寬度搭配不同調變因子數值的設定不會影響PTV劑量的包覆率。統計分析不同靜態式照野寬度電腦治療計劃各群組中，結果顯示靜態式照野寬度大小設定對於各危急器官劑量有顯著性差異（p＜0.0001）。照野寬度越大危急器官所接受的劑量越大。若考慮病患各危急器官接受到最低輻射劑量，其最佳的優化演算參數設定為照野寬度1 cm搭配調變因子2.2，其次為照野寬度2.5 cm搭配調變因子2.8，但照野寬度越小所需治療時間就越久。若顧慮到臨床上無法長時間久躺的病患，則可以選擇照野寬度2.5 cm搭配調變因子2.8。

關鍵字

螺旋刀；照野寬度；調變因子；攝護腺

並列摘要

This study was to evaluate the influence of the static field width (FW) and modulation factor (MF) on the organs at risk (OAR) dose and treatment time of prostate cancer by tomotherapy. CT scans of a Rando phantom were used to prepare the radiotherapy treatment plan. Planning target volume and the organs at risk (OAR) corresponding to prostate cancer were contoured in the CT scan. Forty-two tomotherapy plans with the same parameter setting (importance and penalty) were obtained with static FW values including 1.0 cm and 2.5 cm, combined with the different value of MF (range of 1.0-5.0 with step 0.2). Treatment plan with different FW resulted a significant difference in the OAR dose (p ＜ 0.0001). As the larger the width of the larger organ doses received. To reduce absorbed dose of critical organ, the clinically optimized algorithm with MF 2.2 plus FW 1.0cm was suggested. The second choice combination was MF 2.8 plus FW 2.5 cm. However, small field width will significantly increase treatment time. Considering some patient could not lie down for too long, treatment time could be shortened with combination of MF 2.8 plus FW 2.5 cm.

並列關鍵字

tomotherapy ； field width ； modulation factor ； prostate cancer

國際替代計量

螺旋刀靜態式照野寬度與調變因子參數設定對放射治療攝護腺癌影響：侖道假體研究

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