癌症放射治療的新進展

Recent Advances in Radiation Therapy for Cancer Treatment

除了手術、化學治療、標靶藥物和免疫治療外，放射治療在癌症治療領域中，扮演極重要角色。由於機器和科技日新月異的進展，放射治療從之前的鈷60治療儀器，一直演進到現在以光子治療為主的直線加速器（linear accelerator, LA）、螺旋刀（tomotherapy），伽馬刀（gamma knife）以及電腦刀（cyberknife）和磁振造影影像導引全方位放射線治療儀（MRI-LA）等新式儀器。這些新式儀器的治療精確度、治療品質及機器穩定性均有長足之進步。同時放射治療技術，也從之前的3D順形治療，進步到目前以強度調控放射治療（intensity-modulated radiation therapy, IMRT）和弧形強度調控放射治療（volumetric modulated arc therapy, VMAT）為主的放射治療技術。相較於過去傳統技術而言，IMRT可大幅減少放射治療相關毒性，達到更佳的醫療效益。而VMAT除可達到較佳的放射設計治療品質外，且使高劑量儘量集中於腫瘤區域，並讓正常組織之傷害降低，提高治療效果及減輕副作用。相較於IMRT，VMAT可同時大幅增加臨床執行效率和減少治療時間等優勢。除此之外，直線加速器可以利用內建的影像工具，錐狀射束電腦斷層掃描（cone beam computed tomography, CBCT），搭配影像導引（image guidance）之功能，在每次治療前進行對位校正，減少放射治療中可能發生之位移誤差，並提高治療精準度。雖然IMRT和VMAT等最新的光子治療技術，可讓病人之腫瘤獲得更大的劑量，也讓腫瘤旁的正常組織減輕更多的副作用。但因X光能量雖有減少皮膚放射線劑量，但X光穿透能力強，在腫瘤前後方其劑量可能會造成正常組織之傷害，為了進一步提升治療效果，和減輕正常器官的副作用，目前放射治療則在質子、重粒子和硼中子捕獲治療等粒子治療新技術，獲得持續性的進展以及創新。然而不同的粒子治療技術，仍具有不同的臨床優勢和適應症以及限制性，目前仍無法完全取代光子治療，來治療癌症。透過持續的研究、經驗累積和國內及國際合作，才能發揮這些先進技術在癌症治療的優勢。

In addition to surgery, chemotherapy, targeted agents, and immunotherapy, radiotherapy plays a crucial role in the multimodality treatment of cancer. Owing to rapid advancements in machinery and technology, radiotherapy has evolved from cobalt-60 treatment equipment to the current linear accelerator (LA), tomotherapy, gamma knife, cyberknife, magnetic resonance imaging (MRI)-guided LA, and other innovative devices. These modern instruments have significantly improved in terms of machine stability, radiation precision, and overall performance. Radiotherapy techniques have also progressed from early three-dimensional conformal treatment to more advanced approaches, such as intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). Compared with earlier conventional techniques, IMRT provides enhanced dose distribution to the tumor site while substantially reducing radiation therapy-induced damage to surrounding tissues. VMAT not only improves the quality of radiation delivery but also minimizes harm to healthy tissues, enhances treatment efficacy, and reduces side effects by focusing high radiation doses on the tumor. Furthermore, VMAT can significantly shorten treatment time and improve clinical execution efficiency compared with IMRT. The use of linear accelerators, integrated with image-guidance tools such as cone-beam computed tomography (CBCT), allows for the correction of displacement errors before each treatment. This integration increases treatment precision and ensures accurate alignment during radiotherapy. Although photon therapy can reduce the radiation dose to the skin, its high penetration power results in radiation being delivered both anterior and posterior to the tumor, which may damage surrounding healthy tissues. In contrast, newer particle therapy modalities—including proton therapy, heavy particle therapy, and boron neutron capture therapy—aim to further enhance treatment outcomes and minimize adverse effects of radiation on healthy organs. However, these therapies differ in terms of clinical benefit, indication, and limitations, and are not yet capable of fully replacing photon therapy in cancer treatment. The benefits of these cutting-edge radiotherapy technologies for cancer treatment can only be realized through ongoing research, experiential learning, and domestic and international cooperation.