放射線治療 : state of the art and in future

Technical innovation in radiation therapy such as stereotactic irradiation, intensity modulated radiation therapy, image-guided radiation therapy, and brachytherapy using remote controlled after-loading system have made it possible to deliver ideally distributed radiation dose to the target with great accuracy, while sparing the adjacent organs at risk. As a result, tumor control rate by radiation therapy improved markedly and became excellent alternative to surgery for asymptomatic or mildly symptomatic brain tumors, early stage lung cancer, and low-risk prostate cancer. In locally advanced stage of cancer, randomized controlled trials put the chemoradiation therapy forward a standard treatment option for patients with head and neck cancer, lung cancer, esophageal cancer, and uterine cervical cancer. Radiation therapy is also a effective treatment method for palliation of local symptoms caused by cancer with consistently high response rates. Minimmaly invasive therapy has come to be emphasized its needs against the background of increased tendency of elderly patients with cancer, and advances in conformal dose delivery technique raise the radiation therapy at a more important position in the medical care for cancer. However, adequate number of radiation therapy profession is indispensable to manage highlysophisticated radiation therapy technology. It is our current issue to establish the education system bringing up radiation therapy professions including a radiation oncologist, a medical physicist, a dosimetrist, and a radiation therapy technologist.