鼻咽癌斜位眼眶下照射部位之問接驗證

Indirect Verification of Oblique Infraorbital Portal in Nasopharyngeal Carcinoma

顏上惠(Sang-Hue Yen) ； 林光大(Kuang-Tah Lin) ； 梁錦榮(Mien-Jung Liang) ； 蕭正英(Cheng-Ying Shiau) ； 陳光耀(Kuang Y. Chen)

《放射治療與腫瘤學》 2卷2期 (1995/06) Pp. 151-156

https://doi.org/10.6316/TRO/199502(2)151

摘要

利用眼眶下放射治療部位於鼻咽癌之放射治療可減少大腦顯葉、中耳、內耳、顯顎關節等正常組微之劑量，因此可減少其後遺症“傳統之驗證片向來認為不易驗證此斜位治療部位，此研究的目的乃在發展一問接方法可正確驗證此斜位眼眶下照射部位。我們使用事先做好病人模擬攝影位置時固定之設施與面具，然後送病人做電腦斷層攝影。取鼻咽部位處之一系列橫軸切面影像，界定出腫瘤之範圍，同時並畫出所有影像縱向中線。我們使用一與影像5公分寬同樣放大率之紙條，儘量能涵蓋鼻咽及咽旁區，然後以此部位之中軸與橫軸電腦斷層之中線交又點為旋轉軸中，選取40°~50°向左右兩側旋轉，使能涵蓋對側之鼻咽及咽旁區，同側大部份之鼻咽及咽旁區而不直接照射到脊髓，再將此紙條旋轉至水平（側位），然後將此部位之後綠做記號於此系列影像上，再連接這些記號成一線，即為此側位照野之後綠。若準直儀再配合以適當角度的旋轉及阻擋鉛塊的製作，即可得斜位照野之問接驗證，於鼻咽癌斜位目則匡下部位之治療是適當且可信賴的。本文的結論認為在三維電腦治療計畫系統普遍使用之前，此法為一簡單方便有效之正確驗證方法，可減少治療之晚期副作用，達到提昇治療效益(therapeutic gain)的目的。

關鍵字

間接驗證 ； 斜位眼眶下照野 ； 鼻咽癌 ； 依據電腦斷層攝影之模擬定位

並列摘要

Using the infra orbital portals in the treatment of the nasopharyngeal carcinoma allows radiation oncologists to reduce the dosage to the temporal lobes, middle and inner ears, and temporomandibular joints, therefore, the morbidities of normal tissues can he minimized. It has been thought difficult to verify these portals by using the traditional simulation techniques and films. This study is to develop an indirect method to accurately verify the oblique infraobital portals. We sent the NPC patient for CT scan with a mask and immobilization devices as in simulation position. Serial axial cuts are used to delineate the tumor margin. A midline is drawn at all cuts of images at the nasopharynx level. Use a paper strip with same magnification rate of 5cm as CT image's as the portal width covering the most nasopharyngeal and parapharyngeal areas, then get the cross point of the portal central line and the midline of axial cuts as the rotation center. Rotate the paper strip in the angle of 40-50 degree bilaterally to cover the nasopharyngeal and parapharyngeal areas on the contralateral side and the most nasopharyngeal and parapharyngeal areas on the ipsilateral side without irradiating the spinal cord. Then rotate the paper strip again to the horizontal (true lateral) position. Mark the posterior margin of the treatment portals on the image of axial cuts. Connect these markers into a line as the posterior margin of true lateral portal. With a suitable collimator angulation and the necessary block making, an indirect method for verification of this position is obtained. This technique allows us to correctly irradiate the oblique infraorbital portal with reliable verification. Applying indirect verification of oblique infraorbital portal in nasopharyngeal carcinoma, is feasible and reliable. This study shows that indirect verification for delivering the oblique infraorbital portal is not only a simple, convenient procedure for the patients, technologists and physicians, but also an effective way to achieve the therapeutic gain in the treatment of nasopharyugeal carcinoma.

並列關鍵字

Indirect verification ； Oblique infraorbital portal ； Nasopharyngeal carcinoma ； CT based simulation