分段照野技術在全乳乳癌放射治療的臨床應用

Clinical Applications of Segmental Field Technique for Tangential Intact Breast Irradiation Therapy

張東浩(Tung-Hao Chang) ； 林招膨(Jao-Perng Lin) ； 劉幕台(Mu-Tai Liu) ； 黃昭源(Chao-Yuan Huang) ； 張雅婷(Ya-Ting Chang) ； 陳苑蓉(Yuan-Rong Chen) ； 蘇淑梅(Shu-Mei Su) ； 虞希堯(His-Yao Yu)

《中華放射線醫學雜誌》 25卷2期 (2000/04) Pp. 59-65

摘要

一般乳癌治療常會在病人乳房內上下側、乳頭部位產生高劑量區或肺部產生高劑量的熱區，使病人腋下或乳頭附近的皮膚反應劇烈，及肺部必須接受過多劑量，而產不不良的副作用。本文目的即是藉由強度調控的觀念，利用照野分段技術除去高劑量熱區的存在，使靶位置內的劑量分佈更均勻，並減少皮膚效應及肺部所接受到的劑量。
本文乳癌治療模式採兩個相切照野，來治療乳房、胸腔壁、內乳淋巴結及腋下淋巴結，並另於照野內探分段性的強度調控，利用多葉式準直儀於各射束內增加一個擋掉肺部和一個擋掉高劑量區的射束，以除去高劑量區的存在，使腫瘤內劑量更為均勻。本實驗先以擬人假體作治療計畫，藉以比較三度空間順形治療計畫與照野分段技術計畫的差異。另外再以此技術應用於單一實際病患的電腦斷層影像，並觀察高劑量區劑量的變化。
在ADAC治療計畫系統內分析擬人假體與實際病患的等劑量曲線，實行照野分段計畫其劑量均勻性由原來109%~114%提高為104%~105%左右，肺部劑量明顯減少。高劑量區域位置由原來位於肺部、腋下或乳頭附近轉移至乳房較深處，所以對於腋下或乳頭附近之皮膚反應也因高劑量區轉移而可得到相當程度的改善。
利用多葉式準直儀，分段照野技術－於傳統照野內外加較小的照野治療，可以提高乳房劑量的均勻性，且可減少高劑量區和減少肺部所接受的劑量，因此可有效減少病患治療後之副作用。

關鍵字

乳癌 ； 分段照野技術 ； 多葉式準直儀 ； 熱區

並列摘要

In general, using tangential breast irradiation can produce hot spots in the lung and nipple. This paper illustrates a way to achieve a more uniform dose distribution for breast cancer treatment using simple multiple sets of a multi-leaf collimator (MLC).
We applied two tangential fields to treat patient’s right breast, chest wall, internal mammary chain, and axillary lymph nodes. Intensity modulation using two MLC segments was a “field-within-a-field” technique. The first MLC set was designed to spare as much of the lung as possible, while the second set of fields was designed to reduce the hot region around the nipple. The dose distribution was calculated by and ADAC treatment planning system on the right breast of a Rando phantom and an actual patient. We evaluated the difference of hot regions between 3D planning and multiple MLC fields.
The dose uniformity in breast treatment was improved from 109%~114% to 104%~105%. The lung volume receiving these high doses could be significantly decreased. The hot regions shifted from the lung or nipple to the target.
Dose uniformity can be improved by using a “field-within-a-field” technique. This technique not only reduced the dose to the lung but also decreased doses to hot regions. Therefore this simple static approach can introduce intensity modulation into the clinic, and should improve the outcome for many breast cancer patients.

並列關鍵字

Breast cancer ； Segmental field technique ； Multi-leaf collimator ； Hot spots