利用濾片改善影像導引放射治療驗證片之品質-以頭頸部癌症為例
Use filter to improve quality of verification film for Imagine–Guided Radiation Therapy- An Example of Head and Neck Cancer
中文摘要
放射治療是癌症治療的方式之一，約有 35~45%的癌症病患接受放射治療。許多 早期常見癌病的治癒率高達 80%-90%以上，原位癌更是接近 100%﹔即使是中晚 期腫瘤，由於手術、放射線、化學治療及標靶治療的持續發展，使得成功率亦屢 有突破。尤其，放射線治療近二十年已進入三度空間放射線治療的時代，諸如立 體定位放射手術(Stereotacticradiosurgery；SRS)、三度空間順形放射治療(3D Conformal Radiotherapy； CRT)、強度調控放射治療(Intensity Modulated Radiation Therapy；IMRT)，及正熱門的影像導引放射治療（Image Guided Radiation Therapy；
IGRT），皆使得放射治療照射得比以前更精準，許多腫瘤的局部控制率不斷提
升，且副作用亦逐漸下降。影像導引放射治療於近幾年的臨床應用以及研究上，
其結果都顯示該技術對於日常擺位誤差的校正有明顯的效益。本研究的動機，是 對身體厚度落差較大的治療部位，X 光經過人體後會造成衰減的強度不同，所造 成影像品質對比差異大，相對的，自動比對軟體比對的效果則不彰，因此，本研 究的目的在於應用濾片補償在治療病灶厚度較薄的治療部位，將多餘的光子衰 減，改善擺位驗證影像比品質，使影像灰階強度提高，影像資訊增加，使電腦比 對的準確度提升，確保治療的準確性與效果。研究方法分為三個部分，第一部使 用仿人體組織假體，分析電腦斷層模擬定位機(CT simulator)之數位式影像重建 X 光攝影(Digital Reconstructed Radiography; DRR)與有無使用濾片之擺位驗證片的 影像灰階強度與校正位移的數據，第二部分採用放射物理游離輻射與物質作用的 物理公式，找出身體組織厚度與濾片之間的相對應關係；最後，則將第二部分所 求出的數據，實際應用在臨床 15 位頭頸部癌症患者上；所得的資料皆以相依樣 本 T 檢定統計進行分析；本研究結果顯示，使用濾片之擺位驗證片前後的影像 灰階強度與校正位移有顯著的差異(P<0.05)，身體組織厚度與濾片之間的相對應 關係，則採用骨骼組織相對應公式換算表，實際應用於臨床 15 位頭頸部癌症病 患的擺位驗證片照射，校正位移的數據在各個擺位方向顯示，前後位方向較容易 產生擺位的誤差，表示使用濾片改善影像導引放射治療驗證片的影像品質有正向
的幫助。
英文摘要
The radiotherapy is one of the ways of treatment of cancer. Nearly 35%~45% of the cancer patients accept the radiotherapy. The cure rate of a lot of early common cancer is up to more than 80%-90%, and carcinoma in situ cancer is close to 100% ,
especially. Later period tumor, surgery, radioactive rays, chemical treatment and mark sustainable development of treatment in being, make success rate also repeat have
breakthroughs. Especially, the radiation therapy has already entered the area for radiation therapy of three-dimensional space in the past 20 years, for example stereotacticradiosurgery (SRS), three-dimensional conformal radiotherapy, intensity modulated radiation therapy (IMRT), And image guided radiation therapy (IGRT), All make the radiation therapy shine more accurate than before, the control rate of part of a lot of tumors is improving constantly, and the side effect also gradually to reduce.
Image guided radiation therapy in clinical application and study of recent years, the result in daily position error correct is benefit. The motive of this research is the treatment part to the body thickness with larger drop, the X-rays will cause the
intensity of decaying in different human tissues, and the image quality contrast caused is widely differently. Relative, the compare result is not complete in the automatic system. Therefore, the main goal of this research is use filter in thin thickness of treatment part that decay redundant photons and improve image quality of verification film. It will be raise gray scale intensity of the image and image information. The research techniques have three parts. The first part is use phantom for analysis gray scale intensity and correction shift between DRR of CT simulator and verification film of with and without filter. The second part is use a formula of the free radiation of physics and physical on action of material, and find out corresponding relation between the bodies and organize the thickness. Finally, apply the data that the second part data to 15 clinical cases of head and neck cancer patients. All the collected data using part T-test are carried on the analysis. This research shows that the gray scale intensity and correction shift have revealed a big difference before and after using filter in verification film (P<0.05). Corresponding relation between the bodies and organize the thickness is choose bone tissues corresponding relation table for applied to 15 clinical cases of head and neck cancer patients in irradiate of verification film.
In each direction of correction shift data shows that anterior-posterior direction is more position error than each direction. It indicates that the whole research represents that using filter to improve quality of verification film for image guided radiation therapy give a positive approach.
