目的：本實驗之目的是探討螺旋式斷層強度調控放射治療(Tomotherapy)是否能進一步地減少肺部劑量。材料與方法：本實驗選取8位肺癌病人，其中5位只有一處原發癌需要照射，其他3位除了原發癌外，合併有2到3處肺部淋巴轉移，每位病人同時做出兩個治療計畫，包括Tomotherapy與固定旋轉臂(gantry)角度的強度調控放射治療(fixed gantry angle IMRT)，最後評估兩個治療計畫，在雙側正常肺、腫瘤同側正常肺與對側正常肺之劑量。除肺癌原發病人外，肺部多發性轉移、乳癌與胸骨轉移病人，各有一位，以初步探討胸部照射的病人，在兩種不同治療技術下肺劑量之優劣。結果：在8位肺癌病人的治療計畫中，Tomotherapy平均可以減少雙側正常肺的平均劑量4.0%（中位數－2.5%，範圍－0.2%~-7.2%，p=0.006），若分為同側正常肺與對側正常肺來看，tomotherpy平均可以減少同側正常肺約7.7%的平均劑量（中位數－7.6%，範圍－17.8%~-1.0%，p=0.003），但對對側正常肺，使用Tomotherapy並沒有明顯的統計意義（平均＋8.0%，中位數－3.1%，範圍－22.3%~+63.2%，p=0.20）。對於肺部多發性轉移、乳癌及胸骨轉移的三位病人，Tomotherapy減少肺部平均劑量達27.3%、3.6%、10.2%。結論與討論：經過仔細的計畫後，對於照射肺部的病人，使用Tomotherapy有潛力減少或維持與IMRT一樣的雙側正常肺與同側正常肺的平均劑量，不過仍須進一步的研究來確認。

Purpose: The purpose of this experiment is to compare the lung dose between fixed-angle IMRT technique and Tomotherapy. We also explore the possibility to lower the lung dose with Tomotherapy. Material and Method: Eight patients were selected for this study. Five of them only have one primary tumor. The others have one primary tumor with two or three lymph node metastasis. All of them were both planned by fixed gantry angle IMRT technique and Tomotherapy technique. The dose distributions and the mean dose to ipsilateral, contralateral and both normal lungs were evaluated and compared between two plans. For completeness, we also evaluate the lung mean dose for a sternum metastasis patient, a multiple lung metastasis patient and a breast cancer patient between fixed-angle IMRT technique and Tomotherapy technique. Result: By comparing the isodose plan of eight patients, Tomotherapy group has lowered mean dose to both normal lung (4.0% lower in average, median: -2.5%, range: -0.2%~-7.2%, p=0.006) and to ipsilateral normal lung (7.7% lower in average, median: -7.6%, range: -17.8%~-1.0%, p=0.003). But for the contralateral normal lung, Tomotherapy technique doesn’t show the statistically significant superiority than fixed-angle IMRT technique (median: -3.1%, range: -22.3%~+63.2%, p=0.20). For patients with multiple lung metastasis, with sternum metastases and with breast cancer, Tomotherpy can reduce the mean dose for whole normal lung by 27.3%, 3.6% and 10.2% respectively. Conclusion and Discussion: With carefully planning, the Tomotherapy plan could have the same or lower mean dose of ipsilateral and both normal lungs than fixed-angle IMRT. Tomotherapy may have potential to reduce more mean dose to lung than fixed-angle IMRT. We need further investigation to verify this potential.