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Vol.54 No.7 contents | Japanese/English |
 | Full Text of PDF (1515K) Article in Japanese |
- Review Article -
Particle Beam Therapy: Proton Beam Therapy and Carbon Ion Radiotherapy
Hitoshi Ishikawa1, Kayoko Ohnishi1, Masashi Mizumoto1, Yoshiko Oshiro1, Toshiyuki Okumura1, Hideyuki Sakurai11Department of Radiation Oncology, University of Tsukuba, Faculty of Medicine, Japan
Objective and Methods. Particle therapy (PT) using protons and carbon ions, which exhibit a spread-out Bragg peak (SOBP), offers advantageous physical properties over radiotherapy (RT), with a superior dose distribution for the target volume according to specified beam modulations versus RT using photons. The effectiveness and feasibility of stereotactic body radiation therapy (SBRT) for stage I non-small cell lung cancer (NSCLC) with photons, protons and carbon ions particles have been reported, although the differences in treatment outcomes remain unclear. In this report, we therefore discuss good candidates for PT by comparing the findings of our treatment planning study and conducting a review of the previous literature. Results. SBRT using photons usually uses more than six fixed beams or rotational non-coplanar beams, whereas PT can be applied to achieve a similar dose distribution using only two to four fixed beams. As previous studies have shown dose-volume effects associated with the development of radiation-induced cardiopulmonary morbidities after thoracic RT, PT has the potential to reduce the volume of the lung irradiated with a low to middle dose of radiation, thus improving the rate of morbidity. In fact, many studies of SBRT for stage I NSCLC using photons have reported rates of grade 3 morbidities in the lungs widely ranging from 0% to 28%, whereas all reports concerning PT have documented rates of less than 8%, primarily because PT is not affected by the size, location or shape of the primary tumor. In fact, there are little benefits of PT for small-sized tumors located in the peripheral lung based on our results of a dose-volume histogram analysis of irradiated normal lung tissues. On the other hand, many studies have indicated that the rates of local control and survival among patients with T2 tumors are inferior to those for T1 disease. It is also well known that carbon ions display a relatively high level of biological effectiveness resulting from a high degree of linear energy transfer. Because the cytocidal effect of these ions is estimated to be approximately three times that of photons, these agents are promising tools for the treatment of patients with T2 tumors. Conclusions. PT using protons and carbon ions is an attractive treatment option for stage I NSCLC, and the application of novel techniques, such as the spot-scanning method, will further reduce the rate of radiation-induced lung injury.
key words: Lung cancer, Carbon ion radiotherapy, Proton beam therapy, Dose-volume histogram, Radiation-induced lung injury
JJLC 54 (7): 917-925, 2014
