@article{oai:repo.qst.go.jp:00047175,
 author = {Mori, Shinichiro and Shinoto, Makoto and Yamada, Shigeru and 森 慎一郎 and 山田 滋},
 issue = {2},
 journal = {Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology},
 month = {May},
 note = {Purpose: We evaluated respiratory-gated carbon-ion beam dose distribution with boost irradiation in pancreatic therapy and compared results between the passive scattering and layer-stacking (a kind of semi-active scanning) irradiation techniques.
Materials and Methods: A total of 21 patients who were treated with conventional passive carbon-ion beam for pancreatic cancer underwent 4DCT imaging under free-breathing conditions. We defined two types of clinical target volume (CTV) for the initial and boost irradiations: CTV1 included the gross tumor volume (GTV) and peripheral organs, and CTV2 included the GTV only with an added uniform 2-mm margin. Planning target volumes 1 and 2 (PTV1 and PTV2) were calculated by adding the range variation considered internal margin defined by 4DCT to the respective CTVs. The initial prescribed dose (= 45.6Gy(RBE); RBE-weighted absorbed dose) was given to PTV1, and the boost dose was increased up to 26.4Gy(RBE) and given to PTV2. Dose assessments were compared between irradiation techniques using the paired t-test.
Results: D95(GTV, CTV2) values were increased from 44.2Gy(RBE) with the prescribed dose of 45.6Gy(RBE) to 69.8Gy(RBE) with the prescribed dose of 72.0Gy(RBE) with both irradiations. Layer-stacking irradiation reduced excessive dosing to normal tissues compared with passive scattering irradiation, particularly for boost irradiation. 1st-2nd portion V20/V40, and stomach V20 values up to the prescribed dose of 48.0, 60.0, and 52.8Gy(RBE) were smaller than those in passive scattering irradiation without boost. Kidney V15/V30 (0.6%(P=0.05)/0.1%(P>0.20) for right kidney, 10.4%(P<0.01)/3.2%(P<0.01) for left kidney), pancreas V20/V40 (88.6%(P<0.01)/83.0%(P<0.03)), duodenum 3rd-4th portion V20/V40 (23.6%(P<0.01)/9.5%(P>0.06)), and stomach V20 (16.3%(P<0.01)) values in layer-stacking irradiation were smaller than those in passive scattering irradiation up to the prescribed dose of 72.0Gy(RBE) and also smaller than those with passive scattering irradiation without boost irradiation (= 45.6Gy(RBE)).
Conclusions: In pancreatic particle beam therapy, delivery of the prescribed dose by layer-stacking boost irradiation provides a greater reduction in excessive dose to normal tissues than delivery by passive scattering irradiation.},
 pages = {258--263},
 title = {Four-dimensional treatment planning in layer-stacking boost irradiation  for carbon-ion pancreatic therapy},
 volume = {111},
 year = {2014}
}